TW201350926A - Producing method for light diffusion film - Google Patents

Abstract

The present invention is aiming to provide a method for effectively producing a light diffusion film having a long length shape, and a light diffusion film thereof, which can spread effectively a diffusion area of incident light. Thus, the present invention relates to a method for producing a light diffusion film having a long length shape and having specific louver-structure regions, including steps (a) to (e) as described in below; (a) a process for preparing a composition for the light diffusion film, (b) a process for forming a first coating layer, (c) a process for forming a first louver structure regions by irradiation of the first active energy ray with a linear light source, to the first coating layer, (d) a process for forming a second coating layer on the first coating layer to produce a laminated body, and (e) a process for forming a second louver structure regions by irradiation of the second active energy ray with a linear light source, to the second coating layer, wherein, an acute angle θ 1 is set to be a value within a range of 10 to 90 DEG, which is observed from above of the film and which is an angle between the long axis direction of the linear light source using as the first active energy irradiation ray and the long axis direction of the linear light source using as the second active energy irradiation ray.

Description

Method for manufacturing light diffusion film

The present invention relates to a method of producing a light diffusing film.

More particularly, the present invention relates to a method for producing a light-diffusing film which can efficiently expand incident light by causing incident light to diffuse not only in a direction along a longitudinal direction thereof but also in a direction orthogonal to a longitudinal direction thereof. A long strip of light diffusing film with a diffused area.

Conventionally, for example, in the field of optical technology to which a liquid crystal display device or the like belongs, a light diffusion film capable of diffusing incident light from a specific direction in a specific direction and directly transmitting incident light from a direction other than the specific direction has been proposed. use.

As such a light-diffusing film, various methods are known, and in particular, a light-diffusing film having a louver structure in which a plurality of plate-like regions having different refractive indices are alternately arranged in either direction along the film surface is provided. It is widely used (for example, Patent Documents 1 to 2).

That is, Patent Document 1 discloses a light control plate (light diffusion film) which is a plastic sheet which selectively scatters incident light of two or more angular ranges.

Further, Patent Document 1 discloses a method of manufacturing a light control plate (light diffusion film), which is characterized in that the first step and the second step are as follows: in the first step, a difference in refractive index is different between the plurality of refractive indexes. A resin composition comprising a compound having one or more polymerizable carbon-carbon double bonds in a molecule is maintained in a film form, and the composition is cured by irradiating ultraviolet rays from a specific direction. In the second step, the resin is obtained on the obtained cured product. The composition is maintained in a film form, and is cured by irradiating ultraviolet rays from a direction different from the first step, and the second step is repeated as necessary.

Further, Patent Document 2 discloses a projection screen in which a plurality of light control films (light diffusion films) are laminated, and the light control film (light diffusion film) has an angle in terms of haze. Dependence, and when the light is incident on the surface at an angle of 0 to 180°, the light scattering angle range (light diffusion incident angle region) showing a haze of 60% or more is 30° or more, wherein, as shown in FIG. 23a~ As shown in FIG. 23b, two of the plurality of light control films (light diffusion films) are laminated such that the directions of the light scattering angle regions (light diffusion incident angle regions) are almost orthogonal.

Patent Document 1: Japanese Laid-Open Patent Publication No. SHO63-309902 (Application No.)

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-316354 (Application No.)

However, in the case of continuously producing a large amount of the light-diffusing film, the coating layer composed of the composition for a light-diffusion film is moved by a conveyor or the like, and the coating layer is irradiated with an active energy ray using a linear light source. Thereby, a light diffusion film having a prescribed louver structure is manufactured.

Therefore, in Patent Document 1, it has been found that a light diffusion film that diffuses incident light in a direction along the moving direction of the coating layer, that is, in the longitudinal direction of the film, can be obtained, but it cannot be obtained. A light diffusing film that diffuses light in a direction orthogonal to the longitudinal direction of the film.

More specifically, in order to obtain a light-diffusing film in which incident light is diffused in a direction orthogonal to the longitudinal direction of the film, it is necessary to form a louver structure composed of a plate-like region extending in the longitudinal direction of the film.

Therefore, in Patent Document 1, when such a louver structure is to be formed, the linear light source is arranged such that the long-axis direction of the linear light source is along the direction in which the coating layer moves.

However, even if the linear light source is configured in this way, since it is viewed from the moving direction section of the coating layer At the time, the respective positions in the width direction of the surface of the coating layer are different, and the active energy rays from the linear light source are irradiated at different angles, so that the light diffusion characteristics of the obtained light diffusion film are also uneven.

Therefore, in the cited document 1, if it is desired to obtain a long-length light-diffusing film that diffuses incident light in a direction orthogonal to the longitudinal direction thereof, it is first necessary to obtain a film along the width direction when the film is viewed from above. A light diffusing film of a louver structure formed by a plate-like region. Next, it is necessary to join the plurality of light diffusion films by cutting them and changing the direction of 90°. Therefore, it has been found that there is a problem that the light diffusibility at the seam portion becomes uneven or the strength of the film is easily lowered.

Further, in Citation 1, the extending direction of the plate-like region in the louver structure obtained in the first step is substantially parallel to the extending direction of the plate-like region in the louver structure obtained in the second step.

Therefore, it has been found that there is a problem that it is impossible to cause the incident light to diffuse light in a direction orthogonal to the longitudinal direction thereof.

On the other hand, in Patent Document 2, as shown in Figs. 23a to 23b, two of the plurality of light-diffusing films are stacked such that the directions of the light-diffusing incident angle regions are almost orthogonal, so that it can be considered at a glance. The incident light is diffused not only in the direction along the longitudinal direction thereof but also in a direction orthogonal to the longitudinal direction thereof.

However, in the case of continuously producing a large amount of the light-diffusing film, it is necessary to irradiate the active energy ray with a linear light source while moving the coating layer composed of the composition for a light-diffusion film with a conveyor or the like.

Therefore, for the same reason as in Patent Document 1, it is difficult to obtain the light diffusion film 221 which diffuses the incident light in a direction orthogonal to the longitudinal direction of the film as shown in FIG. 23a.

Therefore, as a result, even if the light-diffusing film disclosed in Patent Document 2 is obtained, if the long-length light-diffusing film 221 which diffuses the incident light in the direction orthogonal to the longitudinal direction thereof as shown in FIG. 23a is obtained, It also creates the necessity of joining a plurality of light diffusion films, so the patent In the case of Document 1, similarly, the light diffusibility at the joint portion becomes uneven, or the strength of the film is liable to lower.

Therefore, it has been found that the diffusion area of the incident light cannot be effectively expanded by causing the incident light to diffuse light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof.

In such a case, a long-length light diffusion film which is easily applied to a large screen or the like without causing problems such as seams is sought.

In other words, a method of manufacturing a long-length light-diffusing film that efficiently expands the diffusion area of incident light by diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof is sought.

Therefore, the inventors of the present invention have made intensive efforts in view of the above circumstances, and as a result, found that in the manufacturing method including the secondary active energy ray irradiation step in which the linear light source has been used, the secondary active energy ray irradiation step is performed. The relationship between the arrangement angles of the respective linear light sources is defined as a predetermined range, and a long-length light diffusion film that solves the above problems can be obtained, thereby completing the present invention.

That is, an object of the present invention is to provide a method for producing a light-diffusing film which can efficiently produce light diffusion by causing incident light to be directed not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof. Therefore, the elongated light diffusion film that effectively expands the diffusion area of the incident light.

According to the present invention, it is possible to provide a method for producing a light-diffusing film which is characterized in that a plurality of plate-like regions having different refractive indices are sequentially arranged from the bottom in the film thickness direction of the film. The first louver structure in which the louver structure is alternately arranged in parallel in any direction of the film surface, and the method for producing the long-length light diffusion film of the second louver structure, and includes the following steps (a) to (e):

(a) a step of preparing a composition for a light-diffusing film containing two polymerizable compounds having different refractive indices; (b) a step of applying a composition for a light-diffusing film to a process sheet to form a first coating layer; c) a step of forming a first louver structure by irradiating the first coating layer with a linear light source to form a first louver structure while moving the first coating layer; (d) forming a first louver a first coating layer having a structure, a step of applying a composition for a light-diffusing film to form a laminate comprising a first coating layer and a second coating layer, and (e) a step of forming a second coating layer The laminate of the first coating layer and the second coating layer is moved, and the second active energy ray is irradiated with a linear light source to form a second louver structure. When viewed from above the film, the first active energy is made. The acute angle θ 1 formed by the long-axis direction of the linear light source at the time of line irradiation and the long-axis direction of the linear light source when the second active energy ray is irradiated is a value within a range of 10 to 90°.

In other words, in the method for producing a light-diffusing film of the present invention, the relationship between the arrangement angles of the linear light sources is set to a predetermined range in the secondary active energy ray irradiation step using the linear light source, so that the efficiency can be improved. An elongated light-diffusing film in which the extending direction of the plate-like region in the first louver structure and the extending direction of the plate-like region in the second louver structure are intersected at a predetermined angle is manufactured.

Therefore, it is possible to efficiently manufacture a long-length light diffusion film that efficiently expands the diffusion area of the incident light by diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof.

More specifically, it can be obtained that light can be made in the direction along the longitudinal direction and in the direction orthogonal to the longitudinal direction thereof without joining a plurality of light diffusion films in the related art. A long strip of light diffusing film that diffuses.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferred that in the step (c), when viewed from above the film, the long-axis direction of the linear light source when the first active energy ray is irradiated and along the The acute angle θ 2 formed by the imaginary line in the moving direction of the coating layer is a value in the range of 10 to 80°, and in the step (e), when viewed from above the film, the second active energy ray is preferably irradiated. The acute axis direction of the linear light source and the acute angle θ 3 formed by the imaginary line along the moving direction of the laminated body of the first coating layer and the second coating layer are in a range of 10 to 80°. .

By doing so, it is possible to more efficiently produce long-length light that efficiently expands the diffusion area of the incident light by diffusing the incident light toward the direction along the longitudinal direction thereof and also toward the direction orthogonal to the longitudinal direction thereof. Diffusion film.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferred that in the step (e), when viewed from above the film, the long-axis direction and the second activity of the linear light source when the first active energy ray is irradiated The long-axis direction of the linear light source at the time of the irradiation of the energy ray is linearly symmetrical with respect to the imaginary line orthogonal to the moving direction of the laminated body composed of the first coating layer and the second coating layer.

By doing so, the incident light can be more uniformly diffused in the obtained light diffusion film.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferred that in the steps (c) and (e), the first active energy ray is carried out through a light-shielding plate having a long-groove active energy ray transmitting portion. The irradiation and the second active energy ray are irradiated, and the longitudinal direction of the active energy ray transmitting portion is preferably a direction parallel to the long axis direction of the linear light source.

By doing so, it is possible to efficiently produce long strip light that efficiently expands the diffusion area of the incident light by diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof. Diffusion film.

Further, in the method for producing a light-diffusing film of the present invention, it is preferable that the peak illuminance of the surface of the first coating layer when the first active energy ray is irradiated in the step (c) is 0.1 to 50 mW/cm ^{2 .} The value in the range of the first coating layer is a value in the range of 5 to 300 mJ/cm ² .

By doing so, the first louver structure can be formed more efficiently.

Incidentally, the term "peak illuminance" as used herein means a measured value of a portion where the active energy ray on the surface of the first coating layer to be irradiated shows a maximum value.

Further, in the method for producing a light-diffusing film of the present invention, it is preferable that the peak illuminance of the surface of the second coating layer when the second active energy ray is irradiated in the step (e) is 0.1 to 50 mW/cm ^{2 .} The value in the range of the second coating layer is a value in the range of 5 to 300 mJ/cm ² .

By doing so, the second louver structure can be formed more efficiently.

Here, the term "peak illuminance" refers to a measured value of a portion where the active energy ray on the surface of the second coating layer to be irradiated shows the maximum value.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferable to set the film thickness of the first coating layer to a value in the range of 80 to 700 μm in the step (b), and in the step (d) In the case where the film thickness of the second coating layer is in the range of 80 to 700 μm .

By doing so, the first and second louver structures can be formed more efficiently.

Further, in carrying out the method for producing a light-diffusing film of the present invention, the moving speed of the first coating layer in the step (c) and the first coating layer and the second coating in the step (e) are preferably used. The moving speed of the layered laminate is a value in the range of 0.1 to 10 m/min.

By doing so, the first louver structure and the second louver structure can be formed more efficiently.

1a‧‧‧1st coating layer

1a'‧‧‧The first coating layer formed with the first louver structure

1b‧‧‧2nd coating layer

1c‧‧‧A laminate composed of a first coating layer and a second coating layer

2‧‧‧Technical sheet

10‧‧‧Light diffusing film

12‧‧‧ Plate area with relatively high refractive index

13‧‧‧ Louver structure

13a‧‧‧1st louver structure

13b‧‧‧2nd louver structure

The boundary surface of the 13'‧‧‧ louver structure

14‧‧‧Plate area with relatively low refractive index

20‧‧‧Light diffusing film obtained by the manufacturing method of the present invention

50'‧‧‧Light spread

51′‧‧‧Diffusion of diffused light

120‧‧‧UV irradiation device

121‧‧‧thermal radiation cut-off filter

123‧‧‧ visor

125‧‧‧Line light source

150‧‧‧Active energy line

1a to 1b are diagrams for explaining the outline of the louver structure in the light diffusion film.

2a to 2b are diagrams for explaining incident angle dependency, anisotropy, and opening angle in the light diffusion film.

3a to 3c are views for explaining a basic configuration of a light diffusion film obtained by the production method of the present invention.

4a to 4d are diagrams for explaining respective steps in the manufacturing method of the present invention.

5a to 5b are diagrams for explaining the irradiation of active energy rays using a linear light source.

6a to 6b are diagrams for explaining the arrangement angle of the linear light source.

Fig. 7 is another diagram for explaining the irradiation of active energy rays using a linear light source.

8a to 8e are diagrams for explaining the relationship between the arrangement angle of the linear light source and the diffusion area of the incident light.

9a to 9e are photographs for explaining the relationship between the arrangement angle of the linear light source and the diffusion area of the incident light.

10a to 10b are diagrams for explaining the structure of the louver.

11a to 11b are views for explaining the shape of the long light diffusing film.

Fig. 12 is a view for explaining the configuration of the long-length light-diffusing film of the first embodiment.

13a to 13b are photographs for explaining the cross section of the long-length light diffusion film of Example 1.

14a to 14b are views for explaining the light diffusion characteristics of the elongated light diffusion film of Example 1.

Fig. 15 is a view for explaining the configuration of the long-length light-diffusing film of Comparative Example 1.

16a to 16b are photographs for explaining the cross section of the long-length light diffusion film of Comparative Example 1.

17a to 17b are spectrograms and photographs for explaining the light diffusion characteristics of the elongated light diffusing film of Comparative Example 1.

18a to 18c are views for explaining the configuration of the first coating layer in which the first louver structure is formed in Comparative Example 2.

Fig. 19 is a view for explaining the configuration of the long-length light-diffusing film of Comparative Example 2.

20a to 20b are photographs for explaining the cross section of the long-length light diffusion film of Comparative Example 2.

21a to 21b are spectrograms and photographs for explaining the light diffusion characteristics of the non-seam portion of the long-length light diffusion film of Comparative Example 2.

22a to 22b are spectrograms and photographs for explaining the light diffusion characteristics of the joint portion of the long-length light-diffusing film of Comparative Example 2.

23a to 23b are views for explaining a conventional light diffusion film.

The embodiment of the present invention is a method for producing a light-diffusing film, which has a plurality of plate-like regions having different refractive indices in a film thickness direction along the film thickness direction from the bottom. The first louver structure in which the directions are alternately arranged in parallel, and the method for producing the long-length light-diffusing film of the second louver structure include the following steps (a) to (e): (a) preparing a refractive index difference 2 a step of a composition for a light-diffusing film of a polymerizable compound; (b) a step of applying a composition for a light-diffusing film to a process sheet to form a first coating layer; (c) a step of forming a first coating layer; The first coating layer is moved while the first coating layer is moved, and the first louver structure is irradiated with a linear light source to form a first louver structure; (d) the first coating layer having the first louver structure is coated. a step of forming a laminate of the first coating layer and the second coating layer in the composition for a light diffusion film; (e) applying the first coating layer and the second coating layer to the second coating layer The layered structure is moved, and the second active energy ray is irradiated with a linear light source to form a second Axis direction louver structure of the linear light source, wherein, when viewed from above the membrane, so that the first active energy ray irradiation to the longitudinal direction of the linear light source when the active energy ray irradiation of the second acute angle [theta] 1 formed by The step of a value in the range of 10 to 90°.

Hereinafter, the embodiments of the present invention will be specifically described with reference to the drawings, but in order to facilitate the understanding of the description, first, the basic principle of light diffusion of the light diffusion film and the method for producing the light diffusion film of the present invention are obtained. The basic configuration of the predetermined light diffusion film will be described.

1. The basic principle of light diffusion of light diffusion film

First, the basic principle of light diffusion of the light diffusion film will be described using FIGS. 1 to 2.

First, FIG. 1a shows a plan view (plan view) of the light diffusion film 10, and FIG. 1b shows a light diffusion film when the light diffusion film 10 shown in FIG. 1a is cut in the vertical direction along the broken line AA and the cut surface is viewed from the arrow direction. 10 section view.

2a shows an overall view of the light diffusion film 10, and FIG. 2b shows a cross-sectional view of the light diffusion film 10 of FIG. 2a as seen from the X direction.

As shown in the plan view of Fig. 1a, the light-diffusion film 10 is provided with a plate-like region 12 having a relatively high refractive index and a plate-like region 14 having a relatively low refractive index alternately arranged in parallel in any direction along the film surface. Louver structure 13.

In other words, when the film is placed on a horizontal surface, the film has a louver structure composed of a plate-like region extending in the horizontal direction.

Further, as shown in the cross-sectional view of Fig. 1b, the plate-like region 12 having a relatively high refractive index and the plate-like region 14 having a relatively low refractive index each have a predetermined thickness even in the normal direction (film thickness direction) of the light-diffusing film 10. On top, it also maintains a state of being alternately arranged in parallel.

Thereby, as shown in FIG. 2a, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused through the light diffusion film 10.

That is, as shown in FIG. 1b, the incident angle of the incident light to the light diffusing film 10 is a value from a parallel to a predetermined angular range with respect to the boundary surface 13' of the louver structure 13, in other words, a value in the light diffusing incident angle region. At this time, it is estimated that the incident light (52, 54) passes through the inside of the relatively high refractive index plate-like region 12 in the louver structure, while changing direction, along the film thickness direction It passes through, so that the traveling direction of the light on the light-emitting surface side becomes different.

As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused through the light diffusion film 10 (52', 54').

On the other hand, when the incident angle of the incident light to the light diffusing film 10 is outside the light diffusing incident angle region, as shown in FIG. 1b, it is estimated that the incident light 56 is diffused without passing through the light diffusing film, and directly transmitted through the light diffusing film 10 (56). ').

In the present invention, the "light-diffusing incident angle region" refers to an angular range of incident light corresponding to the emitted diffused light when the angle of incident light from the point light source is changed with respect to the light-diffusing film.

In addition, the above-mentioned "light-diffusing incident angle region" means an angular region defined for each of the light-diffusing films in accordance with the refractive index difference, the tilt angle, and the like of the louver structure in the light-diffusing film, as shown in FIG. 2a.

According to the above basic principle, the light diffusion film 10 having the louver structure 13 can exhibit an incident angle dependency in light transmission and diffusion, for example, as shown in FIG. 2a.

In addition, as shown in Figures 1a-2b, a light diffusing film having a single louver structure 13 typically has "anisotropic".

Here, "anisotropy" in the present invention means that, as shown in FIG. 2a, there is a diffusion of the light which is pre-diffused in the plane parallel to the film when the incident light is diffused by the film ( The expanded shape of the diffused light has a property that varies depending on the direction in the plane.

More specifically, as shown in FIG. 2a, light diffusion is selectively generated for components of the incident light that are perpendicular to the orientation of the louver structure extending in either direction along the film surface. On the other hand, in the component contained in the incident light, the component which is parallel to the direction of the louver structure extending in any direction along the film surface is less likely to cause light diffusion, and thus anisotropic light diffusion is realized.

Therefore, as shown in FIG. 2a, the expanded shape of the diffused light having an anisotropic light-diffusing film It is roughly elliptical in shape.

Further, as described above, the component of the incident light contributing to light diffusion is mainly a component perpendicular to the direction of the louver structure extending in either direction along the film surface, so as shown in FIG. 2b, in the present invention, When referring to the "incident angle θ 4 " of incident light, it refers to the incident angle of a component perpendicular to the direction of the louver structure extending in either direction along the film surface. In addition, at this time, the incident angle θ 4 means an angle (°) when the angle with respect to the normal line of the incident side surface of the light diffusion film is 0°.

Further, in the present invention, the "light diffusion angle region" refers to an angular range in which the point light source is fixed at an angle at which the incident light is most diffused with respect to the light diffusion film, and the obtained diffused light is obtained in this state.

Further, in the present invention, the "opening angle of the diffused light" is the width of the "light diffusing angle region" as described in Fig. 2b, and is oriented from the louver structure extending in either direction along the film surface. The opening angle θ 5 of the diffused light when the cross section of the film is viewed in the parallel direction X.

Further, as shown in FIG. 2a, in the case of the light diffusion film, when the incident angle of the incident light is included in the light diffusion incident angle region, even if the incident angle is different, almost the same light can be diffused on the light-emitting surface side.

Therefore, it can be said that the obtained light-diffusing film has a condensing action for concentrating light at a predetermined position.

In addition, the direction change of the incident light inside the high refractive index region 12 in the louver structure is changed linearly in a zigzag manner by total reflection as shown in FIG. 1b. In addition to the case of the step index type, a case of a gradient index type in which the direction is changed in a curved shape may be considered.

In addition, in FIGS. 1a to 1b, for the sake of simplicity, the interface between the plate-like region 12 having a relatively high refractive index and the plate-like region 14 having a relatively low refractive index is represented by a straight line, but actually, the interface is slightly meandered, each The slab-like region forms a complex refractive index distribution structure accompanying branching and disappearing.

As a result, it is estimated that these complex effects on the light diffusion characteristics.

2. Basic composition

Next, the basic configuration of the light diffusion film obtained by the production method of the present invention will be described with reference to Figs. 3a to 3c.

That is, as shown in Fig. 3c, the light diffusing film 20 obtained by the manufacturing method of the present invention has the first louver structure 13a and the Fig. 3b shown in Fig. 3a in order from the bottom in the film thickness direction of the film. The second louver structure 13b is shown.

Further, the extending direction of the plate-like region of the first louver structure 13a shown in Fig. 3a is different from the extending direction of the plate-like region of the second louver structure 13b shown in Fig. 3b, and intersects when viewed from the film upper direction.

Therefore, in the light diffusion film 20 obtained by the production method of the present invention, the light incident on the film is first anisotropically diffused by, for example, the second louver structure 13b as shown in Fig. 3b.

Then, the diffused light that is anisotropically diffused by the second louver structure 13b is further diffused by anisotropic light in a direction different from that of the second louver structure 13b by the first louver structure 13a as shown in FIG. 3a.

As a result, as shown in FIG. 3c, the light incident on the light diffusion film 20 of the present invention is diffused into a rectangular shape by light, whereby the diffusion area of the incident light can be effectively enlarged.

In addition, the above "lower" means that when the coating layer is provided on the process sheet, the coating layer is closer to one side of the process sheet in the film thickness direction. Therefore, it is a simple term for explaining the present invention, and does not impose any restriction on the vertical direction of the light-diffusing film itself.

In addition, the "diffusion area of incident light" means that, as shown in FIG. 3c, when the incident light is diffused through the film, the pre-diffused emitted light is distributed in a plane parallel to the film at a predetermined distance from the film. area.

Hereinafter, a method of producing the light diffusion film according to the present embodiment will be described in detail.

3. Step (a): Preparation steps of the composition for a light diffusing film

Step (a) is a step of preparing a composition for a predetermined light-diffusing film.

More specifically, it is preferably a step of mixing at least two kinds of polymerizable compounds having different refractive indices, a photopolymerization initiator, and other additives as required.

Further, in the case of mixing, it is possible to directly stir at room temperature, but from the viewpoint of improving uniformity, for example, it is preferred to stir under heating at 40 to 80 ° C to form a uniform mixed liquid.

Further, it is preferred to further add a diluent solvent to achieve a desired viscosity suitable for coating.

Hereinafter, step (a) will be more specifically described.

[29] (1) High refractive index polymerizable compound

(1)-1 type

Among the two kinds of polymerizable compounds having different refractive indices, the type of the polymerizable compound having a relatively high refractive index (hereinafter sometimes referred to as the component (A)) is not particularly limited, and it is preferred that the main component contains a plurality of aromatic rings. (meth) acrylate.

The reason for this is that, as a component (A), a polymerizable compound having a polymerization rate of (A) component which is relatively lower than a refractive index can be obtained by containing a specific (meth) acrylate (hereinafter sometimes referred to as a component). The polymerization rate of the component (B) is fast, and a predetermined difference is caused in the polymerization rate between the components, whereby the copolymerizability of the two components is effectively lowered.

As a result, in the case of photocuring, a so-called louver structure in which a plate-like region of the component (A) and a plate-like region derived from the component (B) are alternately formed can be efficiently formed.

Further, it is presumed that the component (A) contains a specific (meth) acrylate, and although it has sufficient compatibility with the component (B) in the monomer phase, it can be in a plurality of connected stages in the polymerization process. The compatibility with the component (B) is lowered to a predetermined range, and the louver structure is further efficiently formed.

Further, as the component (A), by containing a specific (meth) acrylate, The refractive index of the plate-like region from the component (A) in the louver structure can be increased, and the difference in refractive index from the plate-like region derived from the component (B) can be adjusted to a predetermined value or more.

Therefore, by including a specific (meth) acrylate, it is possible to efficiently obtain a louver structure in which plate-like regions having different refractive indices are alternately extended by including a specific (meth) acrylate.

In addition, the "(meth)acrylate containing a plurality of aromatic rings" means a compound having a plurality of aromatic rings in the ester residue portion of the (meth) acrylate.

Further, "(meth)acrylic" means both acrylic acid and methacrylic acid.

In addition, examples of the (meth) acrylate containing a plurality of aromatic rings as the component (A) include biphenyl (meth)acrylate, naphthyl (meth)acrylate, and bismuth (meth)acrylate. Ester, benzyl phenyl (meth) acrylate, biphenyl oxyalkyl (meth) acrylate, naphthyloxyalkyl (meth) acrylate, decyl oxyalkyl (meth) acrylate a (meth) acrylate obtained by substituting an ester, a benzyl phenyloxyalkyl (meth) acrylate or the like, or a part of a hydrogen atom on the aromatic ring with a halogen, an alkyl group, an alkoxy group, a halogenated alkyl group or the like. Wait.

In addition, the (meth) acrylate containing a plurality of aromatic rings as the component (A) is preferably a compound containing a biphenyl ring, and particularly preferably a biphenyl compound represented by the following formula (1).

[33] (In the formula (1), R ¹ to R ¹⁰ are each independently, and at least one of R ¹ to R ¹⁰ is a substituent represented by the following formula (2), and the remainder is a hydrogen atom, a hydroxyl group, or a carboxyl group. , an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, a carboxyalkyl group, and any substituent in a halogen atom)

(In the formula (2), R ¹¹ is a hydrogen atom or a methyl group, the number of carbon atoms n is an integer of 1 to 4, and the number of repetitions m is an integer of 1 to 10)

The reason for this is that, as the component (A), by including a biphenyl compound having a specific structure, a predetermined difference can be caused in the polymerization rate of the component (A) and the component (B), and the component (A) can be B) The compatibility of the components is lowered to a predetermined range, and the copolymerizability of the two components is lowered.

Further, it is possible to increase the refractive index of the plate-like region from the component (A) in the louver structure, and it is easier to adjust the difference in refractive index from the plate-like region derived from the component (B) to a predetermined value or more.

Further, when R ¹ to R ¹⁰ in the formula (1) contain any one of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group and a carboxyalkyl group, the number of carbon atoms in the alkyl moiety is preferably A value in the range of 1~4.

The reason is that if the number of carbon atoms exceeds 4, the polymerization rate of the component (A) is lowered, or the refractive index of the plate-like region derived from the component (A) is too low, and it may be difficult to form efficiently. Louver structure.

Therefore, when R ¹ to R ¹⁰ in the formula (1) contain any one of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group and a carboxyalkyl group, it is preferred to have the carbon number of the alkyl moiety The value in the range of 1 to 3 is particularly preferably in the range of 1 to 2.

Further, R ¹ to R ¹⁰ in the formula (1) are preferably a substituent containing a halogenated alkyl group or a halogen atom, that is, a substituent which does not contain a halogen.

The reason for this is to prevent the occurrence of dioxin in the case of incinerating a light diffusion film or the like, and it is preferable from the viewpoint of environmental protection.

In the conventional light diffusing film having a louver structure, when a predetermined louver structure is obtained, halogen substitution is usually performed in the monomer component for the purpose of increasing the refractive index of the monomer component.

In this regard, when the biphenyl compound represented by the formula (1) is used, the refractive index can be high even without halogen substitution.

Therefore, when the light-diffusing film obtained by photocuring the composition for a light-diffusion film of this invention is used, even if it does not contain a halogen, it can exhibit favorable incident angle dependency.

It should be noted that "good incident angle dependency" means that the difference between the light diffusion incident angle region and the non-diffusion incident angle region where the incident light is not diffused and directly transmitted is clearly controlled.

Further, any of R ² to R ⁹ in the formula (1) is preferably a substituent represented by the formula (2).

The reason for this is that the position of the substituent represented by the general formula (2) is a position other than R ¹ and R ¹⁰ , whereby the phase before the photocuring can be effectively prevented, and the components (A) are aligned and crystallized. Chemical.

Further, the monomer stage before photocuring is liquid, and it can be apparently uniformly mixed with the component (B) without using a diluent solvent or the like.

Thereby, at the stage of photocuring, the component (A) and the component (B) can be coagulated and phase-separated at a fine level, and a light-diffusing film having a louver structure can be obtained more efficiently.

Furthermore, from the same viewpoint, any of R ³ , R ⁵ , R ⁶ and R ⁸ in the formula (1) is preferably a substituent represented by the formula (2).

Further, it is usually preferred that the repeating number m of the substituent represented by the formula (2) is an integer of from 1 to 10.

The reason for this is that if the number of repetitions m exceeds 10, the oxyalkylene chain connecting the polymerization site and the biphenyl ring becomes too long, and polymerization of the component (A) at the polymerization site may be inhibited.

Therefore, it is more preferable that the repeating number m of the substituent represented by the general formula (2) is an integer of 1 to 4, and particularly preferably an integer of 1 to 2.

In the same manner, it is preferred that the number of carbon atoms n of the substituent represented by the formula (2) is an integer of from 1 to 4.

In addition, it is preferable to consider that the position of the polymerizable carbon-carbon double bond as the polymerization site is too close to the biphenyl ring and the biphenyl ring is sterically hindered to lower the polymerization rate of the component (A). The number of carbon atoms n of the substituent represented by the formula (2) is an integer of 2 to 4, and is preferably an integer of 2 to 3.

In addition, as a specific example of the biphenyl compound represented by the formula (1), a compound represented by the following formulas (3) to (4) is preferable.

(1)-2 molecular weight

Further, it is preferred that the molecular weight of the component (A) is in the range of 200 to 2,500.

The reason for this is estimated by the fact that the molecular weight of the component (A) is within a predetermined range, whereby the polymerization rate of the component (A) can be further increased, and the copolymerizability of the component (A) and the component (B) can be more effectively reduced.

As a result, in the case of photocuring, the louver structure in which the plate-like region of the component (A) and the plate-like region derived from the component (B) are alternately formed can be formed more effectively.

In other words, when the molecular weight of the component (A) is less than 200, the polymerization rate is lowered due to steric hindrance, and the polymerization rate of the component (B) is close to the polymerization rate of the component (B). . On the other hand, when the molecular weight of the component (A) is more than 2,500, the difference in molecular weight with the component (B) is small, and the polymerization rate of the component (A) is also lowered to become the component (B). The polymerization rate is close to each other, and it is estimated that copolymerization with the component (B) is likely to occur, and as a result, it may be difficult to form the louver structure efficiently.

Therefore, it is preferable to make the molecular weight of the component (A) in the range of 240 to 1,500, and more preferably in the range of 260 to 1,000.

Incidentally, the molecular weight of the component (A) can be determined from a calculated value obtained from the molecular composition and the atomic weight of the constituent atom, and the weight average molecular weight can also be measured by gel permeation chromatography (GPC).

(1)-3 used alone

Further, the composition for a light-diffusing film of the present invention is characterized in that the component (A) is contained as a monomer component which forms a plate-like region having a relatively high refractive index in the louver structure, but it is preferable to contain the component (A) in a single component. .

The reason for this is that, by configuring in this manner, it is possible to effectively control the fluctuation of the refractive index from the plate-like region of the component (A), that is, the plate-like region having a relatively high refractive index, and more efficiently obtain the light diffusion having the louver structure. membrane.

In other words, when the compatibility of the component (A) with respect to the component (B) is low, for example, when the component (A) is a halogen compound or the like, the other component (A) (for example, a non-halogen compound) may be used in combination. The third component which is compatible with the component (A) and the component (B).

However, at this time, the refractive index of the plate-like region having a relatively high refractive index from the component (A) fluctuates or is likely to be lowered due to the influence of the third component.

As a result, the difference in refractive index of the plate-like region having a relatively low refractive index from the component (B) may become uneven or may be excessively lowered.

Therefore, it is preferred to select a monomer component having a high refractive index which is compatible with the component (B) and use the component as a separate component (A).

In addition, when the biphenyl compound represented by the formula (3) which is the component (A) is a low viscosity, it is compatible with the component (B), and therefore can be used as a separate component (A). use.

(1)-4 refractive index

Further, it is preferable that the refractive index of the component (A) is in the range of 1.5 to 1.65.

The reason for this is that, by setting the refractive index of the component (A) to a value within the above range, the refractive index from the plate-like region of the component (A) and the plate-like region derived from the component (B) can be more easily adjusted. The difference in refractive index makes it possible to obtain a light diffusing film having a louver structure more efficiently.

In other words, when the refractive index of the component (A) is less than 1.5, the difference in refractive index from the component (B) is too small, and it may be difficult to obtain an effective light diffusion angle region. On the other hand, when the refractive index of the component (A) exceeds 1.65, the difference in refractive index from the component (B) becomes large, but the apparent compatibility with the component (B) may be obtained. The state is also difficult to form.

Therefore, it is preferable to make the refractive index of the component (A) in the range of 1.52 to 1.65, and more preferably in the range of 1.56 to 1.6.

It should be noted that the refractive index of the above component (A) means before curing by light irradiation. The refractive index of the (A) component.

Further, the refractive index can be measured, for example, in accordance with JIS K0062.

(1)-5 content

In addition, it is preferable that the content of the component (A) in the composition for a light-diffusion film is in the range of 25 to 400 parts by weight based on 100 parts by weight of the component (B) of the polymerizable compound which is relatively low in refractive index to be described later. value.

The reason is that when the content of the component (A) is less than 25 parts by weight, the ratio of the component (A) to the component (B) is small, and the width of the plate-like region derived from the component (A) is small. It is excessively smaller than the width of the plate-like region from the component (B), and it is sometimes difficult to obtain a louver structure having a good incident angle dependency. Further, the length of the louver in the thickness direction of the light diffusion film is insufficient, and the light diffusibility may not be displayed. On the other hand, when the content of the component (A) is more than 400 parts by weight, the ratio of the component (A) to the component (B) increases, and the width of the plate-like region derived from the component (A) comes from The width of the plate-like region of the component (B) is excessively large, and it may be difficult to obtain a louver structure having a good incident angle dependency. Further, the length of the louver in the thickness direction of the light diffusion film is insufficient, and the light diffusibility may not be exhibited.

Therefore, it is more preferable that the content of the component (A) is in the range of 40 to 300 parts by weight based on 100 parts by weight of the component (B), and more preferably in the range of 50 to 200 parts by weight.

(2) Low refractive index polymerizable compound

(2)-1 type

The type of the polymerizable compound having a relatively low refractive index (the component (B)) is not particularly limited, and examples of the main component thereof include urethane (meth) acrylate. a (meth)acrylic polymer having a (meth)acrylinyl group in the side chain, an organic terpene resin containing a (meth)acrylonitrile group, an unsaturated polyester resin, etc., but particularly preferably a urethane (methyl group) )Acrylate.

The reason for this is that if urethane (meth) acrylate is used, it is possible to more easily adjust the difference between the refractive index of the plate-like region derived from the component (A) and the refractive index of the plate-like region derived from the component (B). It is also possible to effectively suppress the fluctuation of the refractive index from the plate-like region of the component (B), and more efficiently obtain a light-diffusing film having a louver structure.

Therefore, urethane (meth) acrylate which is a component (B) will be mainly described below.

In addition, (meth)acrylate means both an acrylate and a methacrylate.

First, urethane (meth) acrylate is formed of (B1) a compound containing at least two isocyanate groups, (B2) a polyol compound, and (B3) a hydroxyalkyl (meth) acrylate, wherein (B2) is preferably The diol compound is preferably a polyalkylene glycol.

Incidentally, the component (B) further contains an oligomer having a repeating unit of a urethane bond.

In addition, examples of the compound containing at least two isocyanate groups as the component (B1) include, for example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 1,3-benzenedimethylene diisocyanate. , an aromatic polyisocyanate such as 4-benzene dimethylene diisocyanate, an aliphatic polyisocyanate such as hexamethylene diisocyanate, an alicyclic polycondensation such as isophorone diisocyanate (IPDI) or hydrogenated diphenylmethane diisocyanate; Isocyanates, and such biuret, isocyanurate, and reactants as low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil An adduct (for example, a benzene dimethylene diisocyanate trifunctional adduct) or the like.

Further, in the above, an alicyclic polyisocyanate is particularly preferable.

The reason for this is that, in the case of an alicyclic polyisocyanate, it is easy to set a difference in the reaction rate of each isocyanate group due to a spatial conformation or the like as compared with the aliphatic polyisocyanate.

Therefore, it is possible to prevent the component (B1) from reacting only with the component (B2), or the component (B1) to react only with the component (B3), and to reliably react the component (B1) with the component (B2) and the component (B3). Prevent the generation of excess by-products.

As a result, it is possible to effectively suppress the fluctuation of the refractive index of the plate-like region derived from the component (B) in the louver structure, that is, the low refractive index plate-like region.

In addition, when it is an alicyclic polyisocyanate, the compatibility of the obtained (B) component and (A) component can be reduced to a predetermined range, and the louver structure can be formed more efficiently than an aromatic polyisocyanate.

Further, when the alicyclic polyisocyanate is used, the refractive index of the obtained component (B) can be made smaller than that of the aromatic polyisocyanate, so that the difference in refractive index from the component (A) can be increased, which makes it more reliable. The light diffusing property is displayed, and the louver structure having high uniformity of the diffused light in the light diffusion angle region is further efficiently formed.

Further, in such an alicyclic polyisocyanate, an alicyclic diisocyanate containing only two isocyanate groups is preferable.

The reason for this is that when the alicyclic diisocyanate is used, it is possible to quantitatively react with the component (B2) and the component (B3) to obtain a single component (B).

As such an alicyclic diisocyanate, isophorone diisocyanate (IPDI) is preferable.

The reason for this is that an effective difference can be provided for the reactivity of two isocyanate groups.

Further, among the components forming the urethane (meth) acrylate, the polyalkylene glycol as the component (B2) may, for example, be polyethylene glycol, polypropylene glycol, polytetramethylene glycol or polyhexanediol. Etc., among them, it is preferably polypropylene glycol.

The reason for this is that if the polypropylene glycol is used, since the viscosity is low, solventless treatment can be performed.

In addition, when the component (B) is cured, the component (B) is a good soft segment in the cured product, and the handleability and mountability of the light-diffusing film can be effectively improved.

Incidentally, the weight average molecular weight of the component (B) can be mainly adjusted by the weight average molecular weight of the component (B2). Here, the weight average molecular weight of the component (B2) is usually 2300 to 19,500, preferably It is 4300~14300, preferably 6300~12300.

Further, among the components forming the urethane (meth) acrylate, as the (B3) component, that is, the hydroxyalkyl (meth)acrylate, for example, 2-hydroxyethyl (meth)acrylate or (methyl) ) 2-hydroxypropyl acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxy butyl (meth) acrylate Ester and the like.

Further, from the viewpoint of lowering the polymerization rate of the obtained urethane (meth) acrylate and forming a predetermined louver structure more efficiently, it is particularly preferably a hydroxyalkyl methacrylate, more preferably a methacrylic acid 2- Hydroxyethyl ester.

Further, the synthesis of urethane (meth) acrylate by the components (B1) to (B3) can be carried out according to a conventional method.

In this case, the ratio of the components (B1) to (B3) is preferably a ratio of (B1) component: (B2) component: (B3) component = 1 to 5: 1:1 to 5 in terms of molar ratio.

The reason for this is that, by the above-mentioned mixing ratio, it is possible to efficiently synthesize and bond the one of the isocyanate groups of the component (B1) and the two hydroxyl groups of the component (B2), and further the hydroxyl group of the component (B3). A urethane (meth) acrylate obtained by reacting and bonding another isocyanate group respectively contained in two (B1) components.

Therefore, it is preferable to make the ratio of the components (B1) to (B3) in the molar ratio (B1) component: (B2) component: (B3) component = 1 to 3: 1:1 to 3 ratio, Especially suitable for a ratio of 2:1:2.

(2)-2 weight average molecular weight

Further, it is preferred that the weight average molecular weight of the component (B) is in the range of from 3,000 to 20,000.

The reason for this is that the weight average molecular weight of the component (B) is within a predetermined range, whereby a predetermined difference in the polymerization rate of the component (A) and the component (B) can be caused, and the copolymerizability of the two components can be effectively reduced.

As a result, when photocuring is performed, the louver structure in which the plate-like region of the component (A) and the plate-like region derived from the component (B) are alternately formed can be efficiently formed.

In other words, when the weight average molecular weight of the component (B) is less than 3,000, the polymerization rate of the component (B) is increased, and the polymerization rate of the component (A) is close to that, and copolymerization with the component (A) is likely to occur. Sometimes it is difficult to form the louver structure efficiently. On the other hand, when the weight average molecular weight of the component (B) is more than 20,000, it may be difficult to form a louver structure in which the plate-like regions of the component (A) and the component (B) are alternately extended, or The compatibility of the component (A) is excessively lowered, and the component (A) is precipitated at the coating stage.

Therefore, it is preferable that the weight average molecular weight of the component (B) is in the range of 5,000 to 15,000, and it is particularly preferably in the range of 7,000 to 13,000.

Incidentally, the weight average molecular weight of the component (B) can be measured by gel permeation chromatography (GPC).

(2)-3 used alone

Further, the component (B) may be used in combination of two or more kinds having different molecular structures and weight average molecular weights. However, from the viewpoint of suppressing the fluctuation of the refractive index of the plate-like region derived from the component (B) in the louver structure, it is preferable to use only 1 Kind.

In other words, when a plurality of components (B) are used, the refractive index of the plate-like region having a relatively low refractive index from the component (B) fluctuates or becomes high, and may be a plate having a relatively high refractive index from the component (A). The difference in refractive index of the region becomes uneven or excessively lowered.

(2)-4 refractive index

Further, it is preferable that the refractive index of the component (B) is in the range of 1.4 to 1.55.

The reason for this is that by setting the refractive index of the component (B) to a value within the above range, it is possible to more easily adjust the difference in refractive index between the plate-like region from the component (A) and the plate-like region from the component (B). A light diffusing film having a louver structure is more efficiently obtained.

That is, when the refractive index of the component (B) is less than 1.4, the component (A) is The difference in refractive index is large, but the compatibility with the component (A) is extremely deteriorated, and the louver structure may not be formed. On the other hand, when the refractive index of the component (B) exceeds 1.55, the difference in refractive index from the component (A) becomes too small, and it may be difficult to obtain a desired incident angle dependency.

Therefore, it is preferable to make the refractive index of the component (B) in the range of 1.45 to 1.54, and particularly preferably in the range of 1.46 to 1.52.

The refractive index of the component (B) is the refractive index of the component (B) before curing by light irradiation.

Further, the refractive index can be measured, for example, in accordance with JIS K0062.

Further, it is preferable that the difference between the refractive index of the component (A) and the refractive index of the component (B) is 0.01 or more.

The reason for this is that by setting the difference in refractive index to a value within a predetermined range, it is possible to obtain a more favorable incident angle dependency in light transmission and diffusion, and a wider light diffusion incident angle region. Light diffusing film.

In other words, when the difference in refractive index is less than 0.01, the angle of total reflection of incident light in the louver structure becomes narrow, and thus the opening angle of light diffusion may become excessively narrow. On the other hand, when the difference in refractive index is an excessively large value, the compatibility between the component (A) and the component (B) is excessively deteriorated, and the louver structure may not be formed.

Therefore, it is preferable that the difference between the refractive index of the component (A) and the refractive index of the component (B) is in the range of 0.05 to 0.5, and it is particularly preferably in the range of 0.1 to 0.2.

The refractive indices of the components (A) and (B) referred to herein mean the refractive indices of the components (A) and (B) before curing by light irradiation.

(2)-5 content

In addition, the content of the component (B) in the composition for a light-diffusing film is preferably in the range of 10 to 80% by weight based on 100% by weight of the total amount of the composition for a light-diffusing film.

The reason is that when the content of the component (B) is less than 10% by weight, the ratio of the component (B) to the component (A) is small, and the width of the plate-like region derived from the component (B) is The width of the plate-like region from the component (A) is excessively small, and it is sometimes difficult to obtain a louver structure having a good incident angle dependency. Further, the length of the louver in the thickness direction of the light diffusion film may be insufficient. On the other hand, when the content of the component (B) is more than 80% by weight, the ratio of the component (B) to the component (A) increases, and the width of the plate-like region derived from the component (B) comes from The width of the plate-like region of the component (A) is excessively large, and it may be difficult to obtain a louver structure having a good incident angle dependency. Further, the length of the louver in the thickness direction of the light diffusion film may be insufficient.

Therefore, it is preferable that the content of the component (B) is in the range of 20 to 70% by weight based on 100% by weight of the total amount of the composition for a light-diffusing film, and particularly preferably in the range of 30 to 60% by weight. value.

(3) Photopolymerization initiator

Further, in the composition for a light-diffusing film of the present invention, it is preferred to contain a photopolymerization initiator as the component (C) as required.

The reason for this is that when the active energy ray is applied to the composition for a light-diffusion film by containing a photopolymerization initiator, the louver structure can be efficiently formed.

Here, the photopolymerization initiator refers to a compound which generates a radical species by irradiation with an active energy ray such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, and acetophenone. , dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl 1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propan-1-one , 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)one, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobiphenyl Ketone, dichlorobenzophenone, 2-methyl hydrazine, 2-ethyl hydrazine, 2-tert-butyl butyl hydrazine, 2-amino hydrazine, 2-methyl thioxanthone, 2-B Thiophenone, 2-chlorothioxanthone, 2,4-dimethylthiophene Ketone, 2,4-diethylthioxanthone, benzoin dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoate, oligo[2-hydroxy-2-methyl In the case of 1-[4-(1-methylvinyl)phenyl]propane], one type may be used alone or two or more types may be used in combination.

In addition, the content in the case where the photopolymerization initiator is contained is preferably in the range of 0.2 to 20 parts by weight based on 100 parts by weight of the total amount of the components (A) and (B), and is preferably 0.5 to 0.5 part by weight. A value in the range of 15 parts by weight is particularly preferably in the range of 1 to 10 parts by weight.

(4) Other additives

Further, additives other than the above compounds may be appropriately added insofar as the effects of the present invention are not impaired.

Examples of such an additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a polymerization accelerator, a polymerization inhibitor, an infrared absorber, a plasticizer, a diluent solvent, and a leveling agent.

In addition, the content of such an additive is usually preferably in the range of 0.01 to 5 parts by weight, preferably 0.02 to 3 parts by weight, based on 100 parts by weight of the total amount of the components (A) and (B). The value in the range is particularly preferably in the range of 0.05 to 2 parts by weight.

4. Step (b): 1st coating step

The step (b) is a step of applying the composition for a light-diffusing film prepared on the process sheet 2 as shown in FIG. 4a to form the first coating layer 1a.

As the process sheet, any of a plastic film and paper can be used.

In addition, examples of the plastic film include a polyester film such as a polyethylene terephthalate film, a polyolefin film such as a polyethylene film or a polypropylene film, and a cellulose film such as a triacetyl cellulose film. And a polyimide film or the like.

Further, examples of the paper include cellophane, coated paper, and laminated paper.

Further, in consideration of the steps to be described later, the process sheet 2 is preferably a plastic film excellent in dimensional stability to heat and active energy rays.

As such a plastic film, a polyester film, a polyolefin film, and a polyimide film are preferable among the plastic film.

Further, after photocuring the process sheet, in order to facilitate the peeling of the obtained light diffusion film from the process sheet, it is preferable to provide a release layer on the coated surface side of the composition for a light diffusion film of the process sheet.

The release layer can be formed using a conventionally known release agent such as an organic ruthenium release agent, a fluorine release agent, an alkyd release agent, or an olefin release agent.

It should be noted that the thickness of the process sheet is usually preferably in the range of 25 to 200 μm .

Further, as a method of applying the composition for a light-diffusing film to a process sheet, for example, a doctor blade method, a roll coating method, a bar coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used. A conventionally known method is carried out.

Moreover, it is preferable that the film thickness of the first coating layer is in the range of 80 to 700 μm .

The reason for this is that the first louver structure can be formed more efficiently by setting the film thickness of the first coating layer to a value within the above range.

In other words, when the film thickness of the first coating layer is less than 80 μm , the length of the first louver structure formed is insufficient, and the incident light traveling straight in the first louver structure increases, and light diffusion may be difficult to obtain. The uniformity of the intensity of the diffused light in the angular region. On the other hand, when the film thickness of the first coating layer is more than 700 μm , when the first coating layer is irradiated with the active energy ray to form the first louver structure, the light is caused by the louver structure formed at the beginning. The direction of travel of the polymerization is diffused, and it is sometimes difficult to form a desired louver structure.

Therefore, it is preferable that the film thickness of the first coating layer is in the range of 100 to 500 μm , and particularly preferably in the range of 120 to 300 μm .

5. Step (c): First active energy ray irradiation step

As shown in FIG. 4b, the step (c) is a step of: making the first coating layer 1a while The first coating layer 1a moves along the movement direction E, and the first louver structure 13a is formed by performing the first active energy ray irradiation 150a using the linear light source 125a.

More specifically, for example, as shown in FIG. 5a, the ultraviolet irradiation device 120 of the condensing mirror 122 for collecting light is provided in the linear ultraviolet lamp 125a (for example, if it is a commercially available product, it is an EYE GRAPHICS strain). The thermal radiation cut-off filter 121 and the light-shielding plates 123 (123a, 123b) are disposed in the company, ECS-4011GX, etc., thereby taking out the active energy rays 150a composed of direct light controlled only by the irradiation angle, and taking the active energy rays 150a The first coating layer 1a formed on the material 2 is irradiated.

Further, as shown in Fig. 6a, it is preferable that the longitudinal direction of the linear light source 125a and the imaginary line E along the moving direction E of the first coating layer 1a when the first active energy ray is irradiated are viewed from above the film. The acute angle θ 2 formed is a value in the range of 10 to 80°.

The reason for this is that by arranging the arrangement angle of the linear light source in this manner, it is possible to efficiently manufacture the incident light not only along the longitudinal direction thereof, but also in combination with the arrangement angle of the linear light source in the step (e) described later. The direction is also a long-length light-diffusing film that diffuses light in a direction orthogonal to the longitudinal direction thereof and effectively expands the diffusion area of the incident light.

In other words, when θ 2 is a value smaller than 10°, it depends on the arrangement angle of the linear light source in the step (e) to be described later, but generally the light diffusion property in the direction along the longitudinal direction of the film is excessively lowered. Sometimes the diffusion area of incident light is excessively small. On the other hand, when θ 2 is a value exceeding 80°, it depends on the arrangement angle of the linear light source in the step (e) to be described later, but generally diffuses light in a direction orthogonal to the longitudinal direction of the film. The characteristics are excessively lowered, and sometimes the diffusion area of the incident light is excessively small.

Therefore, when viewed from above the film, it is preferable that the acute axis θ 2 of the linear light source when the first active energy ray is irradiated and the imaginary line along the moving direction of the first coating layer is 35~ The value in the range of 55° is particularly preferably in the range of 40 to 50°, more preferably in the range of 44 to 46°.

Incidentally, it is preferable that the interval between the linear light source 125a and the coating layer 1a is substantially the same at any position.

Further, as the irradiation angle of the active energy ray, as shown in Fig. 5b, it is generally preferable that the irradiation angle θ 6 when the angle of the normal to the surface of the first coating layer 1a is 0° is -80 to 80°. The value within the range.

The reason for this is that when the irradiation angle is a value outside the range of -80 to 80°, the influence of reflection or the like on the surface of the first coating layer 1a becomes large, and it may be difficult to form a sufficient louver structure.

Further, the irradiation angle θ 6 is preferably a width (irradiation angle width) θ 6' of 1 to 80°.

The reason is that when the irradiation angle width θ 6 ′ is less than 1°, the moving speed of the coating layer must be excessively lowered, and the manufacturing efficiency may be lowered. On the other hand, when the irradiation angle width θ 6 ' is a value exceeding 80°, the irradiation light is excessively dispersed, and it may be difficult to form a louver structure.

Therefore, it is preferable that the irradiation angle θ 6' of the irradiation angle θ 6 is in the range of 2 to 45°, and particularly preferably in the range of 5 to 20°.

Incidentally, when the irradiation angle width θ 6 ' is included, the angle of the intermediate position is taken as the irradiation angle θ 6 .

Further, it is preferable that the first active energy ray is irradiated through the light shielding plate having the long groove-shaped active energy ray transmitting portion, and the longitudinal direction of the active energy ray transmitting portion is a direction parallel to the longitudinal direction of the linear light source.

In addition, as long as the active energy ray transmitting section transmits the state of the active energy ray, it may be any form.

For example, it may be composed of quartz glass, or may be a simple space in which a light-shielding material is not present.

Specifically, as shown in FIG. 7 , it is preferable to carry out the long groove-shaped gap (active energy ray transmitting portion) formed by the two light shielding plates 123 ( 123 a , 123 b ), and the long side direction of the long groove-shaped gap is A direction parallel to the long axis direction of the linear light source 125a.

By arranging the light shielding plate in this manner, the irradiation angle θ 6 of the active energy ray 150 a as shown in FIG. 5 a can be adjusted to a value within a predetermined range, and the position of the surface of the first coating layer 1 a can be effectively suppressed from being different. The active energy rays 150a from the linear light source 125a are illuminated at excessively different angles.

As a result, the inclination angle of the plate-like region in the formed louver structure can be made uniform, and the light diffusion characteristics of the obtained long-length light diffusion film can be made uniform.

Moreover, it is preferable that the peak illuminance of the surface of the first coating layer when the first active energy ray is irradiated is a value in the range of 0.1 to 50 mW/cm ² .

The reason for this is that the peak illuminance at the time of irradiating the first active energy ray is a value within the above range, whereby the first louver structure can be formed more efficiently.

In other words, when the peak illuminance is less than 0.1 mW/cm ² , it may be difficult to form the first louver structure clearly. On the other hand, when the peak illuminance is a value exceeding 50 mW/cm ² , the curing speed is estimated to be too fast, and the first louver structure may not be formed clearly.

Therefore, it is preferable that the peak illuminance of the surface of the first coating layer when the first active energy ray is irradiated is in the range of 0.3 to 10 mW/cm ² , and particularly preferably in the range of 0.5 to 5 mW/cm ² . value.

In addition, it is preferable that the integrated light amount of the surface of the first coating layer when the first active energy ray is irradiated is a value within a range of 5 to 300 mJ/cm ² .

The reason for this is that the first louver structure can be formed more efficiently by setting the integrated light amount at the time of the first active energy ray irradiation to a value within the above range.

In other words, when the integrated light amount is less than 5 mJ/cm ² , it may be difficult to sufficiently extend the first louver structure from the upper side to the lower side. On the other hand, when the integrated light amount is a value exceeding 300 mJ/cm ² , the obtained light-diffusing film may be colored.

Therefore, it is preferable that the integrated light amount on the surface of the first coating layer when the first active energy ray is irradiated is in the range of 10 to 200 mJ/cm ² , and particularly preferably in the range of 20 to 150 mJ/cm ² . value.

Moreover, it is preferable that the moving speed of the first coating layer is a value within a range of 0.1 to 10 m/min.

The reason for this is that the first louver structure can be formed more efficiently by setting the moving speed of the first coating layer to a value within the above range.

In other words, when the moving speed of the first coating layer is less than 0.1 m/min, the productivity may be excessively lowered. On the other hand, when the moving speed of the first coating layer is more than 10 m/min, the curing of the first coating layer, in other words, the formation of the first louver structure is faster, and the active energy ray is applied to the first coating layer. The incident angle of the cloth layer is changed, and the formation of the first louver structure may be insufficient.

Therefore, it is preferable that the moving speed of the first coating layer is in the range of 0.2 to 5 m/min, and particularly preferably in the range of 0.5 to 3 m/min.

Further, it is preferred that the active energy ray is irradiated to the upper surface of the first coating layer in a state in which the active energy ray transmitting sheet is laminated.

The reason for this is that by laminating the active energy ray transmitting sheet, the influence of the oxygen barrier can be effectively suppressed, and the first louver structure can be formed more efficiently.

In other words, by laminating the active energy ray-transmitting sheet on the upper surface of the first coating layer, it is possible to stably prevent the surface of the first coating layer from being in contact with oxygen while transmitting the sheet, and efficiently to the first sheet. The coating layer illuminates the active energy ray.

In addition, as the active energy ray-transmitting sheet, a process sheet which can transmit the active energy ray in the process sheet described in the step (b) (coating step) can be used without particular limitation.

Further, it is preferable to further irradiate the active energy ray differently from the first active energy ray irradiation as the step (c) so that the amount of integrated light that is sufficiently cured by the first coating layer is different.

Since the first coating layer is sufficiently cured, the active energy ray at this time is preferably a random light in any traveling direction without using parallel light.

6. Step (d): 2nd coating step

As shown in Fig. 4c, in the step (d), the composition for a light-diffusing film is applied to the first coating layer 1a' on which the first louver structure 13a is formed, and the first coating layer 1a' and the second coating layer are formed. The laminate 1c composed of the layer 1b.

In the case where the first louver structure 13a is formed, when the active energy ray transmitting sheet is used, the sheet is peeled off to expose the surface of the coating layer 1a', and then the above operation is performed.

In addition, it is preferable that the composition for a light-diffusion film used for formation of the 1st coating layer 1b is the composition of the light-diffusion film similar to the composition for the light-diffusion film used for formation of the 1st coating layer 1a.

The reason for this is that by using the same composition for a light-diffusing film, it is possible to suppress reflection on the interface between the coating layer 1a' and the coating layer 1b', and it is also possible to improve the adhesion.

In addition, as a method of applying the composition for a light-diffusion film on the first coating layer in which the first louver structure is formed, for example, a doctor blade method, a roll coating method, a bar coating method, or a blade coating method can be used. The die coating method, the gravure coating method, and the like are carried out in the same manner as in the above step (b).

Further, it is preferable that the thickness of the second coating layer is in the range of 80 to 700 μm .

The reason for this is that the second louver structure can be formed more efficiently by setting the film thickness of the second coating layer to a value within the above range.

In other words, when the film thickness of the second coating layer is less than 80 μm , the length of the formed second louver structure is insufficient, and incident light that flows straight in the second louver structure increases, and light diffusion may be difficult to obtain. The uniformity of the intensity of the diffused light in the angular region. On the other hand, when the film thickness of the second coating layer is more than 700 μm , when the second coating layer is irradiated with the active energy ray to form the second louver structure, photopolymerization is caused by the louver structure formed at the initial stage. The direction of travel is diffused, and it is sometimes difficult to form a desired louver structure.

Therefore, it is preferable to set the film thickness of the second coating layer to a value in the range of 100 to 500 μm , and more preferably in the range of 120 to 300 μm .

7. Step (e): second active energy ray irradiation step

As shown in Fig. 4d, the step (e) is a step of moving the stratification of the first coating layer 1a' and the second coating layer 1b formed with the first louver structure 13a to the second coating layer 1b. The body 1c is irradiated with the second active energy ray by the linear light source 125b to form the second louver structure 13b, and as shown in Fig. 6b, the first active energy ray is irradiated when viewed from above the film. The acute angle θ 1 formed by the long-axis direction of the linear light source 125a and the long-axis direction of the linear light source 125b when the second active energy ray is irradiated is a value within a range of 10 to 90°.

In other words, in the secondary active energy ray irradiation step in which the linear light source has been used, the plate-like region in the first louver structure can be efficiently manufactured by setting the relationship between the arrangement angles of the respective linear light sources to a predetermined range. An elongated light-diffusing film in which the extending direction and the extending direction of the plate-like region in the second louver structure intersect at a predetermined angle.

Therefore, it is possible to efficiently manufacture a long-length light diffusion film that efficiently expands the diffusion area of the incident light by diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof.

More specifically, when a plurality of light-diffusing films are joined as in the related art, it is possible to obtain long light diffusion in the direction along the longitudinal direction and in the direction orthogonal to the longitudinal direction thereof. Strip light diffusing film.

That is, if the acute angle θ 1 shown in FIG. 6b is a value smaller than 10°, the diffusion area of the incident light may become excessively small.

Therefore, when viewed from above the film, it is preferable that the acute axis θ 1 of the linear light source when the first active energy ray is irradiated and the long axis direction of the linear light source when the second active energy ray is irradiated is The value in the range of 80 to 90° is more preferably in the range of 85 to 90°, and particularly preferably in the range of 89 to 90°.

Further, as shown in Fig. 6b, when viewed from above the film, it is preferable that the long-axis direction of the linear light source 125b and the first coating layer formed by the first louver structure 13a are formed when the second active energy ray is irradiated. The acute angle θ 3 formed by the virtual line E' in the moving direction E of the laminated body 1c of the 1a' and the second coating layer 1b is a value in the range of 10 to 80°.

The reason for this is that by arranging the arrangement angle of the linear light source in this manner, in combination with the arrangement angle of the linear light source in the above step (c), it is possible to more efficiently manufacture the incident light not only along the longitudinal direction thereof. The direction is also a long-length light diffusion film that diffuses light in a direction orthogonal to the longitudinal direction thereof to effectively expand the diffusion area of the incident light.

In other words, when θ 3 is a value less than 10°, it depends on the arrangement angle of the linear light source in the above step (c), but generally the light diffusion characteristic is excessive toward the direction along the longitudinal direction of the film. When it is lowered, the diffusion area of incident light is sometimes too small. On the other hand, when θ 3 is a value exceeding 80°, it depends on the arrangement angle of the linear light source in the above step (c), but generally, the light is orthogonal to the longitudinal direction of the film. The diffusion characteristics are excessively lowered, and the diffusion area of the incident light is sometimes excessively small.

Therefore, when viewed from above the film, it is preferable that the long axis direction of the linear light source when the second active energy ray is irradiated and the moving direction of the laminated body composed of the first coating layer and the second coating layer are used. The angle θ 3 formed by the imaginary line is a value in the range of 35 to 55°, more preferably in the range of 40 to 50°, and particularly preferably in the range of 44 to 46°.

Incidentally, it is preferable that the interval between the linear light source 125b and the coating layer 1b is substantially the same at any position.

Further, the irradiation angle and the irradiation angle width of the active energy ray are preferably the same numerical ranges as those in the case of the first active energy ray irradiation described with reference to Figs. 5a to 5b.

Further, as shown in FIG. 6b, it is preferable that the long axis direction of the linear light source 125a and the long axis direction of the linear light source 125b when the first active energy ray is irradiated when the first active energy ray is irradiated when viewed from above the film, With respect to and composed of the first coating layer 1a' and the second coating layer 1b The imaginary line E〞 orthogonal to the moving direction E of the laminated body becomes line symmetrical.

The reason for this is that the linear light source at the time of the second active energy ray irradiation is arranged such that the incident light is more uniformly diffused in the obtained light diffusion film.

In other words, when θ 2 = 45°, θ 3 = 45°, or a value in the vicinity thereof, the linear light source is arranged in line symmetry, as shown in Fig. 8(a), which will be described later. The expansion in the left-right direction of the diffused light and the enlargement in the vertical direction can be maximized, respectively.

Therefore, when the light diffusing film is applied to a screen, the horizontal viewing angle and the vertical viewing angle can be maximized.

Here, the arrangement angle of the linear light source is used using FIGS. 8a to 8e ( The relationship between the extending direction of the plate-like region and the diffusion area of the incident light will be described.

In other words, in FIGS. 8a to 8e, the first louver structure 13a and the diffusion state 50' incident thereon are shown on the left side, and the second louver structure 13b and the diffused light by the first louver structure 13a incident thereon are shown on the right side. Diffusion 51'.

First, Fig. 8a) shows the diffusion of incident light when θ 1 = 90°, θ 2 = 45°, and θ 3 = 45°, and it is understood that the final incident light diffusion area is sufficiently enlarged (51').

On the other hand, Fig. 8b shows the diffusion of incident light when θ 1 = 60°, θ 2 = 30°, and θ 3 = 30°, and it is known that the direction is along the length direction E' of the film as compared with the case of Fig. 8a. The light diffusion characteristics of the direction diffusion are reduced, and the diffusion area of the incident light becomes small (51').

Further, Fig. 8c shows the diffusion of incident light when θ 1 = 60°, θ 2 = 60°, and θ 3 = 60°, and it is understood that the direction is orthogonal to the longitudinal direction E' of the film as compared with the case of Fig. 8a. The light diffusion characteristic of the direction diffusion is lowered, and the diffusion area of the incident light becomes small (51').

Further, Fig. 8d shows the diffusion of incident light when θ 1 = 30°, θ 2 = 15°, and θ 3 = 15°, and it is known that the direction is along the longitudinal direction E' of the film as compared with the case of Fig. 8a. The diffused light diffusing property is further lowered, and the diffused area of the incident light is further reduced (51').

Further, Fig. 8e shows the diffusion of incident light when θ 1 = 30°, θ 2 = 75°, and θ 3 = 75°, and it is understood that the orientation is orthogonal to the longitudinal direction E' of the film as compared with the case of Fig. 8a. The light diffusion characteristics in the direction are further lowered, and the diffusion area of the incident light is further reduced (51').

Incidentally, photographs of the diffused light corresponding to Figs. 8a to 8e are shown in Figs. 9a to 9e.

Further, as shown in FIG. 7, for the same reason as the case of the first active energy ray irradiation, the second active energy ray irradiation is preferably performed by a long groove-like gap formed by two light-shielding plates, and is long. The longitudinal direction of the groove-like gap is a direction parallel to the long-axis direction of the linear light source.

Moreover, it is preferable that the peak illuminance of the surface of the second coating layer when the second active energy ray is irradiated is a value within a range of 0.1 to 50 mW/cm ² .

The reason for this is that the second louver structure can be formed more efficiently by setting the peak illuminance at the time of irradiation of the second active energy ray to a value within the above range.

In other words, when the peak illuminance is less than 0.1 mW/cm ² , it may be difficult to clearly form the second louver structure. On the other hand, when the peak illuminance is a value exceeding 50 mW/cm ² , the curing speed is estimated to be too fast, and the second louver structure may not be clearly formed.

Therefore, it is preferable that the peak illuminance of the surface of the second coating layer when the second active energy ray is irradiated is in the range of 0.3 to 10 mW/cm ² , preferably in the range of 0.5 to 5 mW/cm ² . value.

Further, it is preferable that the integrated light amount on the surface of the second coating layer when the second active energy ray is irradiated is a value within a range of 5 to 300 mJ/cm ² .

The reason for this is that the second louver structure can be formed more efficiently by setting the integrated light amount at the time of the second active energy ray irradiation to a value within the above range.

In other words, when the integrated light amount is less than 5 mJ/cm ² , it may be difficult to sufficiently extend the second louver structure from the upper side to the lower side. On the other hand, when the integrated light amount is a value exceeding 300 mJ/cm ² , the obtained light-diffusing film may be colored.

Therefore, the integrated light amount on the surface of the second coating layer when the second active energy ray is irradiated is preferably in the range of 10 to 200 mJ/cm ² , more preferably in the range of 20 to 150 mJ/cm ² . value.

In the second active energy ray irradiation, it is preferable to laminate the first coating layer and the second coating layer having the first louver structure, for the same reason as the case of the first active energy ray irradiation. The moving speed of the body is in the range of 0.1 to 10 m/min, preferably in the range of 0.2 to 5 m/min, and more preferably in the range of 0.5 to 3 m/min.

Further, from the same viewpoint as in the case of the step (c), it is preferable to irradiate the active energy ray to the upper surface of the second coating layer in a state in which the active energy ray transmitting sheet is laminated.

Further, it is preferable to further irradiate the active energy ray differently from the second active energy ray irradiation as the step (e) so that the amount of integrated light that is sufficiently cured by the second coating layer is different.

Since the second coating layer is sufficiently cured, the active energy ray at this time is preferably a light that is random in any traveling direction without using parallel light.

Incidentally, the above steps (d) to (e) may be carried out continuously using one conveyor and the steps (b) to (c), or the first louver structure formed by the steps (b) to (c) may be formed. The first coating layer is recovered in the form of a roll, and placed on another conveyor to carry out steps (d) to (e).

Therefore, for the former, the linear light source in the step (c) and the linear light source in the step (e) are separately arranged, and for the latter, the same linear light source can be changed (rotated) by using the arrangement angle. .

8. Light diffusing film

Hereinafter, a light diffusion film obtained by the production method of the present invention will be described.

(1) The first louver structure

(1)-1 refractive index

In the first louver structure, it is preferable to make the difference in refractive index between the plate-like regions having different refractive indices, that is, the refractive index of the plate-like region having a relatively high refractive index and the refractive index of the plate-like region having a relatively low refractive index. The difference in rate is a value of 0.01 or more.

The reason for this is that by setting the difference in refractive index to a value of 0.01 or more, incident light can be stably reflected in the first louver structure, and the incident angle dependency from the first louver structure can be further improved.

More specifically, when the difference in refractive index is less than 0.01, the angular range of total reflection of incident light in the first louver structure is narrow, and the incident angle dependency may be excessively lowered.

Therefore, it is preferable that the difference in refractive index between the plate-like regions having different refractive indices in the first louver structure is 0.03 or more, and is preferably 0.05 or more.

In addition, the larger the difference between the refractive index of the high refractive index plate-like region and the refractive index of the low refractive index plate-like region, the more appropriate, but from the viewpoint of selecting a material capable of forming the first louver structure, it is considered that the upper limit is about 0.3.

Further, in the first louver structure, it is preferable that the refractive index of the plate-like region having a relatively high refractive index is in the range of 1.5 to 1.7.

The reason for this is that if the refractive index of the high refractive index plate-like region is less than 1.5, the difference from the low refractive index plate-like region becomes too small, and it may be difficult to obtain a desired louver structure. On the other hand, when the refractive index of the high refractive index plate-like region is more than 1.7, the compatibility between the material materials of the composition for a light-diffusion film may become excessively low.

Therefore, it is preferable that the refractive index of the high refractive index plate-like region in the first louver structure is in the range of 1.52 to 1.65, and more preferably in the range of 1.55 to 1.6.

Incidentally, the refractive index of the high refractive index plate-like region can be measured, for example, in accordance with JIS K0062.

In addition, in the first louver structure, it is preferable to make the plate having a relatively low refractive index. The refractive index of the region is in the range of 1.4 to 1.5.

The reason for this is that if the refractive index of the low refractive index plate-like region is less than 1.4, the rigidity of the obtained light diffusion film may be lowered. On the other hand, when the refractive index of the low refractive index plate-like region is more than 1.5, the difference in refractive index from the high refractive index plate-like region is too small, and it may be difficult to obtain a desired louver structure.

Therefore, it is preferable that the refractive index of the low refractive index plate-like region in the first louver structure is in the range of 1.42 to 1.48, and more preferably in the range of 1.44 to 1.46.

Incidentally, the refractive index of the low refractive index plate-like region can be measured, for example, in accordance with JIS K0062.

(1)-2 width

Further, as shown in FIG. 10a, in the first louver structure 13a, it is preferable that the widths (S1, S2) of the high refractive index plate-like region 12 and the low refractive index plate-like region 14 having different refractive indices are 0.1 to 15 respectively. A value in the range of μ m.

The reason for this is that by setting the width of the plate-like regions to a value in the range of 0.1 to 15 μm , the incident light can be more stably reflected in the first louver structure, and the first louver can be more effectively improved. The angle of incidence dependence of the structure.

In other words, when the width of the plate-like region is less than 0.1 μm , it is difficult to display light diffusion regardless of the incident angle of the incident light. On the other hand, when the above-described width is a value exceeding 15 μm , the light traveling straight in the first louver structure increases, and the uniformity of the diffused light may be deteriorated.

Therefore, in the first louver structure, it is preferable that the width of the plate-like region having a different refractive index is in the range of 0.5 to 10 μm , and more preferably in the range of 1 to 5 μm .

In addition, the width, length, and the like of the plate-like region constituting the first louver structure can be measured by observing the film cross section by an optical digital microscope.

(1)-3 tilt angle

Further, as shown in FIG. 10a, in the first louver structure, a plurality of high refractive index plate-like regions 12 and a plurality of low refractive index plate-like regions 14 having different refractive indices are preferably constant with respect to the film thickness direction. The inclination angle θ a is arranged in parallel.

The reason for this is that by making the inclination angles θ a of the plate-like regions constant, the incident light can be more stably reflected in the first louver structure, and the incident angle dependency from the first louver structure can be further improved.

In addition, θ a refers to a cross section when the film is cut along a plane perpendicular to the first louver structure extending in any direction along the film surface, and the measured angle with respect to the normal to the film surface Set the inclination angle (°) of the plate-like area at 0°.

More specifically, as shown in FIG. 10a, it means the angle of the narrow side of the angle between the normal line of the end surface of the first louver structure and the uppermost portion of the plate-like region. Incidentally, the inclination angle when the plate-like region is inclined to the left side is referred to as a reference with respect to the inclination angle when the plate-like region shown in FIG. 10a is inclined to the right side.

Further, as shown in Fig. 10b, it is also preferable that the plate-like regions (12, 14) having different refractive indices in the first louver structure are bent from above to below in the film thickness direction of the film.

The reason for this is that by bending the plate-like region, the balance between reflection and transmission in the first louver structure can be complicated, and the opening angle of the diffused light can be effectively enlarged.

Incidentally, such a curved louver structure can be obtained by slowing down the polymerization reaction rate by ultraviolet rays in the thickness direction of the coating film.

Specifically, it is possible to prevent the illuminance of the ultraviolet ray emitted from the linear light source from being moved at a low speed by suppressing the illuminance of the ultraviolet ray emitted from the linear light source.

(1)-4 thickness

Further, it is preferable that the thickness of the first louver structure, that is, the value of the length L1 of the portion of the first louver structure in the normal direction of the film surface as shown in Figs. 10a to 10b, is in the range of 50 to 500 μm . .

The reason for this is that the thickness of the first louver structure is set to a value within the above range, whereby the length of the first louver structure along the film thickness direction can be stably ensured, and the incident light can be more stably stabilized in the first louver structure. The reflection further improves the uniformity of the intensity of the diffused light from the light diffusion angle region of the first louver structure.

In other words, when the thickness L1 of the first louver structure is less than 50 μm , the length of the first louver structure is insufficient, and incident light that travels straight in the first louver structure increases, and it may be difficult to obtain a light diffusion angle region. The uniformity of the intensity of the diffused light inside. On the other hand, when the thickness L1 of the first louver structure is a value exceeding 500 μm , when the composition for a light-diffusing film is irradiated with an active energy ray to form a first louver structure, the structure of the louver formed at an initial stage is caused. The traveling direction of photopolymerization is diffused, and it may be difficult to form a desired first louver structure.

Therefore, it is preferable that the thickness L1 of the first louver structure is in the range of 70 to 300 μm , and more preferably in the range of 80 to 200 μm .

(1)-5 extension direction

Further, it is preferable that the acute angle formed by the extending direction of the plate-like region in the first louver structure and the longitudinal direction of the film is a value within a range of 10 to 80° when viewed from above the film.

The reason for this is that the extending direction of the plate-like region in the first louver structure is set to a value within the above range, and is combined with the extending direction of the plate-like region in the second louver structure, so that the incident light is not only directed along The direction in the longitudinal direction is also diffused in a direction orthogonal to the longitudinal direction thereof, whereby the diffusion area of the incident light can be effectively expanded.

In other words, when the acute angle is less than 10°, the light diffusion characteristics in the direction along the longitudinal direction of the film are generally lowered due to the direction in which the plate-like region in the second louver structure extends. Sometimes the diffusion area of incident light is excessively small. On the other hand, when the acute angle is a value exceeding 80°, the light diffusion property of the plate-like region in the second louver structure is generally diffused in a direction orthogonal to the longitudinal direction of the film. Excessively lowering, sometimes the diffusion area of incident light is excessively small.

Therefore, it is preferable that the acute angle formed by the extending direction of the plate-like region in the first louver structure and the longitudinal direction of the film is 35 to 55° when viewed from above the film, and is preferably 40~. A value in the range of 50° is particularly preferably in the range of 44 to 46°.

(2) 2nd louver structure

Since the configuration of the second louver structure is basically the same as the configuration of the first louver structure, the description thereof will be omitted.

(3) Film thickness

Further, it is preferable that the film thickness of the light-diffusing film is in the range of 50 to 500 μm .

The reason for this is that if the film thickness is less than 50 μm , the length of the louver structure in the film thickness direction formed in the film is excessively shortened, and the incident light traveling straight in the louver structure is increased, which may be difficult to obtain. Full incidence angle dependence. On the other hand, when the film thickness is more than 500 μm , the irradiation light is irradiated for a long period of time, so that the mass productivity is excessively lowered, or the irradiation light is diffused due to the louver structure formed at the beginning, and it may be difficult to form a desired light. Shutter construction.

Therefore, it is preferable to set the film thickness of the light-diffusing film to a value in the range of 70 to 300 μm , and more preferably in the range of 80 to 200 μm .

In the film thickness direction of the light-diffusing film, for example, in the surface layer portion or the like, a portion having no louver structure may be present.

Therefore, the film thickness of the light diffusion film is equal to the total of the thickness of the first louver structure and the thickness of the second louver structure, or exceeds the total thickness of the first louver structure and the thickness of the second louver structure.

(4) Shape of the film

Further, the shape of the light-diffusing film obtained by the production method of the present invention is long in shape.

More specifically, as shown in FIG. 11a, the length L2 in the width direction of the light-diffusing film 10 is preferably in the range of 0.1 to 3 m, and is preferably in the range of 0.5 to 2 m.

On the other hand, the length in the longitudinal direction is not particularly limited.

In other words, in the case of the production method of the present invention, it is possible to continuously produce a light diffusion film which can diffuse light in a direction orthogonal to the longitudinal direction thereof, not only in the direction along the longitudinal direction thereof.

Therefore, it is preferable that the length L3 in the longitudinal direction is a value of 3 m or more, and it is preferably a value of 15 m or more.

The reason for this is that by forming a film having such a shape, it is possible to obtain a strip shape in which the incident light can be diffused not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof. A large area of light diffusing film.

Further, as shown in Fig. 11b, it is preferable that the light diffusion film 20 is wound into a roll shape.

The reason for this is that a light-diffusing film having a long and large area in which light can be diffused in a direction orthogonal to the longitudinal direction of the incident light or in the vicinity thereof can be obtained by forming a roll shape.

In addition, the operability during storage and transportation can be improved.

More specifically, when it is in the form of a roll, the workability is improved as compared with the production while falling on the sheet.

Further, in the case of a roll shape, even when the size of a display or the like to which a film is to be applied is various, it can be subsequently cut into a desired size.

Further, when it is in the form of a roll, it can be bonded to another film by a roll-to-roll method in the next step, and productivity can be improved as compared with the case of a sheet to sheet. .

(5) Combination of extension directions

Further, in the light diffusion film obtained by the production method of the present invention, it is preferable to extend the direction of the plate-like region in the first louver structure and the plate-like region in the second louver structure when viewed from above the film. The acute angle formed by the direction is a value in the range of 10 to 90°.

The reason for this is that, by configuring such a configuration, it is possible to obtain a strip that effectively expands the diffusion area of the incident light by diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof. Film.

That is, when the acute angle is a value smaller than 10°, the diffusion area of incident light may become excessively small.

Therefore, it is preferable that the acute angle formed by the extending direction of the plate-like region in the first louver structure and the extending direction of the plate-like region in the second louver structure is in the range of 80 to 90° when viewed from above the film. The value is more preferably in the range of 85 to 90°, and particularly preferably in the range of 89 to 90°.

(6) adhesive layer

Further, the light-diffusing film obtained by the production method of the present invention has an adhesive layer for laminating the adherend on one surface or both surfaces thereof.

The binder constituting the pressure-sensitive adhesive layer is not particularly limited, and conventionally known binders such as acrylic, organic oxime, urethane, and rubber can be used.

Example

Hereinafter, the method for producing the light-diffusing film of the present invention will be described in detail with reference to the examples.

[Example 1]

1. Synthesis of low refractive index polymerizable compound (B) component

In the container, polypropylene glycol (PPG) 1 mol having a weight average molecular weight of 9,200 as a component (B2) was contained, and in contrast, isophorone diisocyanate (IPDI) as a component (B1) was contained. After 2 moles and 2-hydroxyethyl methacrylate (HEMA) 2 mol as the component (B3), polymerization was carried out according to a usual method to obtain a polyether urethane methacrylate having a weight average molecular weight of 9900.

The weight average molecular weight of the polypropylene glycol and the polyether urethane methacrylate was measured by gel permeation chromatography (GPC) under the following conditions.

. GPC measuring device: manufactured by TOSOH Co., Ltd., HLC-8020

. GPCcolumn: manufactured by TOSOH Co., Ltd. (hereinafter, it is described in order of passage)

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

. Determination of solvent: tetrahydrofuran

. Measuring temperature: 40 ° C

2. Preparation of composition for light diffusion film

Next, acrylic acid having a weight average molecular weight of 268 represented by the following formula (3) as the component (A) is added to 100 parts by weight of the polyether urethane methacrylate having a weight average molecular weight of 9900 as the component (B). 100 parts by weight of o-phenylphenoxyethoxyethyl ester (NK ESTER A-LEN-10, manufactured by Shin-Nakamura Chemical Co., Ltd.) and 5 parts by weight of 2-hydroxy-2-methylpropiophenone as the component (C) Thereafter, the mixture was heated and mixed under the conditions of 80 ° C to obtain a composition for a light-diffusing film.

In addition, the refractive index of the component (A) and the component (B) was measured by an Abbe refractometer (Abe refractometer DR-M2, Na light source, wavelength 589 nm) according to JIS K0062, and the results were 1.58 and 1.46.

3. First coating step

Then, the composition for a light-diffusing film obtained by coating a film-shaped transparent polyethylene terephthalate film (hereinafter referred to as PET) as a process sheet is formed into a first coating having a film thickness of 165 μm . Floor.

4. First active energy ray irradiation step

Next, an ultraviolet irradiation apparatus (ECS-4011GX, manufactured by EYE GRAPHICS Co., Ltd.), which is provided with a condenser lens for collecting light, is provided in the linear high-pressure mercury lamp shown in Fig. 5a.

At this time, when viewed from above the film, the ultraviolet irradiation device is provided such that the acute angle θ 2 of the linear light source and the imaginary line along the moving direction of the first coating layer is 45°.

Next, a light shielding plate is provided on the heat radiation cut filter frame, and the ultraviolet light irradiated onto the surface of the first coating layer is set to be the surface of the first coating layer when viewed from the long axis direction of the linear light source. When the normal line is 0°, the irradiation angle of ultraviolet rays directly directed from the linear light source ( θ 6 in Fig. 5b) becomes 16°.

Further, the height from the surface of the first coating layer to the linear light source was 2000 mm, the peak illuminance was 1.26 mW/cm ² , and the integrated light amount was 23.48 mJ/cm ² .

In addition, in order to prevent the reflected light of the light shielding plate or the like from becoming stray light inside the irradiation machine, the photocuring of the first coating layer is affected. As shown in FIG. 7 , two light shielding plates are also provided in the vicinity of the conveyor. The coating layer is set only by irradiating ultraviolet rays directly emitted from the linear light source.

More specifically, as shown in FIG. 7 , a long groove-shaped gap (gap width: 35 cm) formed by two light shielding plates is formed, and the long-side direction of the long groove-shaped gap becomes a linear light source. The long axis direction is set in a parallel direction.

Then, while the first coating layer was moved at a speed of 1.0 m/min to the right side in FIG. 4b by a conveyor, ultraviolet rays were irradiated, and the length in the longitudinal direction (moving direction of the first coating layer) was 30 m. The first coating layer having the first louver structure in which the length in the width direction is 1.25 m and the film thickness is 165 μm .

Next, in order to achieve reliable curing, a UV-transmissive release film (SP-PET382050, manufactured by Lintec Co., Ltd.; and a center line of the surface on the ultraviolet irradiation side) of a thickness of 38 μm was laminated on the exposed surface side of the first coating layer. The average roughness was 0.01 μm , the haze value was 1.80%, the image sharpness 425, and the transmittance at a wavelength of 360 nm (84.3%)) as an active energy ray-transmitting sheet.

Then, the scattered light was irradiated so that the peak illuminance was 13.7 mW/cm ² and the integrated light amount was 213.6 mJ/cm ² .

In addition, the above-mentioned peak illuminance and the integrated light amount were measured by setting the UV METER (EYE ultraviolet ray illuminance meter UVPF-A1 manufactured by EYE GRAPHICS Co., Ltd.) to the position of the first coating layer.

In addition, the film thickness of the first coating layer in which the first louver structure was formed was measured using a constant pressure thickness measuring device (TECLOCK PG-02J, manufactured by Takara Seisakusho Co., Ltd.).

5. Second coating step

Next, the active energy ray transmission sheet was peeled off from the obtained elongated first coating layer in which the first louver structure was formed.

Then, the exposed surface of the first coating layer on which the first louver structure is formed is applied, and the same combination of light diffusion films as the composition for forming a light-diffusing film used for forming the first coating layer is applied. The second coating layer having a film thickness of 165 μm was formed.

6. Second active energy ray irradiation step

Then, when viewed from above the film, the acute axis θ 1 of the linear light source when the first active energy ray is irradiated and the long axis direction of the linear light source when the second active energy ray is irradiated is 90°. In the same manner as the first active energy ray irradiation step, ultraviolet rays were irradiated in the same manner as in the first active energy ray irradiation step, and a long-length light diffusion film having a first louver structure and a second louver structure and having a thickness of 330 μm was obtained .

In addition, when viewed from above the film, the longitudinal direction of the linear light source and the imaginary line along the moving direction of the laminated body including the first coating layer and the second coating layer in which the first louver structure is formed are described. The acute angle θ 3 is 45°.

In the same manner as in the case of the first coating layer, the second coating layer is irradiated with the scattered light by the active energy ray transmitting sheet (the ultraviolet ray-permeable release film). Curing.

Further, as shown in FIG. 12, the obtained light-diffusing film was confirmed to have a direction in which the plate-like region in the first louver structure extends and a direction in which the plate-like region in the second louver structure extends when viewed from above the film. The acute angle is 90°.

Further, it was confirmed that the acute angle formed by the extending direction of the plate-like region in the first louver structure and the longitudinal direction of the film when viewed from above the film was 45°.

Further, it was confirmed that the acute angle formed by the extending direction of the plate-like region in the second louver structure and the longitudinal direction of the film when viewed from above the film was 45°.

Further, Fig. 13a shows a photograph of a cross section of the obtained light-diffusing film cut along a plane orthogonal to the longitudinal direction of the film, and the obtained light-diffusing film is shown along the length of the film in Fig. 13b. A photograph of a cross section in which the directions are parallel and the plane orthogonal to the film surface is cut.

Incidentally, the cutting of the light-diffusing film was carried out by a razor, and the photographing of the cross-sectional photograph was carried out by an optical microscope (reflection observation).

7. Determination

As shown in FIG. 12, light was incident from the lower side of the obtained light-diffusion film (the side where the first louver structure was located) from the direction orthogonal to the film surface.

Next, a variable angle colorimeter (VC-2 manufactured by Suga Test Instruments Co., Ltd.) was used. A spectrogram of diffused light in a direction orthogonal to the longitudinal direction of the film and in a direction parallel to the longitudinal direction of the film was obtained.

That is, as shown in Fig. 14a, the light diffusion angle (°) of the diffused light diffused by the light diffusion film is taken as the horizontal axis, and the relative intensity (-) of the diffused light is used as the vertical axis.

Here, the spectrogram A shown in Fig. 14a corresponds to diffused light in a direction orthogonal to the longitudinal direction of the film, and the spectrogram B corresponds to diffused light in a direction parallel to the longitudinal direction of the film.

Further, a confocal polarimeter (manufactured by Autronic-MELCHERS GmbH) was used, and as shown in Fig. 14b, a photograph of the diffused light when viewed in the Z direction of Fig. 12 was obtained.

The results shown in the above-mentioned Figs. 14a to 14b are consistent with the light diffusion characteristics predicted from the film having the internal structure as shown in Fig. 12.

[Comparative Example 1]

In Comparative Example 1, a light diffusion film was produced in the same manner as in Example 1 except that the second application step and the second active energy ray irradiation step were not performed.

Further, in the obtained light-diffusing film, as shown in Fig. 15, it was confirmed that the acute angle formed by the extending direction of the plate-like region in the louver structure and the longitudinal direction of the film when viewed from above the film was 45°.

Further, Fig. 16a shows a photograph of a cross section of the obtained light-diffusing film cut along a plane orthogonal to the longitudinal direction of the film, and the obtained light-diffusing film is shown along the length of the film in Fig. 16b. A photograph of a cross section in which the directions are parallel and the plane orthogonal to the film surface is cut.

Further, in the same manner as in Example 1, the light diffusion from the lower side of the obtained light-diffusing film when the film was incident from the direction orthogonal to the film surface was measured.

The spectrum of the obtained diffused light is shown in Fig. 17a, and the photograph of the diffused light when viewed from the Z direction in Fig. 15 is shown in Fig. 17b.

Here, FIG. 17a shows the diffusion direction (long axis direction) of the diffused light shown in FIG. 17b. The spectrum of the direction.

The results shown in the above-mentioned Figs. 17a to 17b coincide with the light diffusion characteristics predicted from the film having the internal structure shown in Fig. 15.

[Comparative Example 2]

In Comparative Example 2, in the first active energy ray irradiation step, when viewed from above the film, the acute angle θ 2 of the longitudinal direction of the linear light source and the imaginary line along the moving direction of the first coating layer is In the same manner as in the first embodiment, a first active energy ray irradiation step was performed on the first coating layer to obtain a first coating layer (a coating layer in which the first louver structure was formed).

With respect to the first coating layer having the first louver structure obtained at this time, as shown in FIG. 18a, it was confirmed that the acute angle formed by the extending direction of the plate-like region in the louver structure and its longitudinal direction was 90 when viewed from above the film. °.

Next, as shown in FIG. 18b, the long first coating layer having the first louver structure obtained is cut every 1.1 m in the longitudinal direction to obtain a plurality of non-first louver structures. Long strip-shaped first coating layer.

Next, as shown in FIG. 18c, the plurality of non-long strip-shaped first coating layers on which the first louver structure is formed are respectively rotated by 90° in a plane, and then arranged in a lateral direction with an interval of 0.5 mm or less. Separately joined.

Thereby, as shown in FIG. 18c, when viewed from above the film, the first shape of the first louver structure in which the extending direction of the plate-like region in the louver structure and the longitudinal direction thereof are 0° is obtained. Coating layer (coating layer of the first louver structure is formed inside).

Next, the first coating layer having the first louver structure obtained as shown in Fig. 18c is laminated on the acrylic transparent adhesive layer having a thickness of 25 μm as shown in Fig. 18a. The long coating layer is a long coating layer having a second louver structure, and a light diffusion film is obtained.

Moreover, as shown in FIG. 19, the obtained light-diffusion film confirmed the extending direction of the plate-like region in the first louver structure and the extending direction of the plate-like region in the second louver structure region as viewed from above the film. The acute angle formed is 90°.

Further, it was confirmed that the acute angle formed by the extending direction of the plate-like region in the first louver structure and the longitudinal direction of the film was 0° when viewed from above the film.

Further, it was confirmed that the acute angle formed by the extending direction of the plate-like region in the second louver structure and the longitudinal direction of the film when viewed from above the film was 90°.

Further, a photograph of a cross section of the obtained light-diffusing film cut along a plane orthogonal to the longitudinal direction of the film shown in Fig. 20a is shown in Fig. 20b along the length of the film. A photograph of a cross section cut in a direction parallel to the plane orthogonal to the film surface.

Further, in the same manner as in Example 1, the light diffusion from the lower side of the obtained light-diffusing film when the film was incident from the direction orthogonal to the film surface was measured.

The spectrum of the diffused light obtained by incident light on the portion where no seam is present is shown in Fig. 21a, and the photograph of the diffused light when viewed from the Z direction in Fig. 19 is shown in Fig. 21b.

The results shown in the above-mentioned Figs. 21a to 21b coincide with the light diffusion characteristics predicted from the film having the internal structure as shown in Fig. 19.

However, when light was incident on a portion of the joint, it was confirmed that the light diffusibility was likely to be uneven due to the joint portion of the film as shown in Figs. 22a to 22b.

[Industrial availability]

As described in detail above, according to the present invention, in the manufacturing method including the secondary active energy ray irradiation step using the linear light source, the relationship between the arrangement angles of the linear light sources in the secondary active energy ray irradiation step is specified. In a predetermined range, it is possible to efficiently manufacture a long strip shape in which the incident light is diffused not only toward the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof, thereby effectively expanding the diffusion area of the incident light. Light diffusing film.

Therefore, the method for producing a light-diffusing film of the present invention is particularly expected to contribute significantly to the productivity and high quality of a large-area light-diffusing film used for projection screens, reflective liquid crystal devices, and the like.

13a‧‧‧1st louver structure

13b‧‧‧2nd louver structure

20‧‧‧Light diffusing film

Claims (8)

A method for producing a light-diffusing film, which has a plurality of plate-like regions having different refractive indices arranged in parallel in any direction along the film surface in order from the bottom in the film thickness direction of the film. A method for producing a long light-diffusing film of a louver structure and a second louver structure; the method for producing the light-diffusing film includes the following steps (a) to (e): (a) preparing two polymerizations having different refractive indices a step of a composition for a light-diffusing film of a compound, (b) a step of applying the composition for a light-diffusing film to a process sheet to form a first coating layer, and (c) a step of forming the first coating layer The first coating layer is moved, the first active energy ray is irradiated with a linear light source to form a first louver structure, and (d) the first coating layer is formed with the first louver structure. a step of applying the composition for a light-diffusing film to form a laminate comprising the first coating layer and the second coating layer, and (e) moving the first coating layer and the second coating layer The laminated body is formed by irradiating the second active layer with a second active energy ray using a linear light source. a louver structure in which a long-axis direction of a linear light source when the first active energy ray is irradiated and a long-axis direction of the linear light source when the second active energy ray is irradiated are viewed from above the film The step of the acute angle θ 1 being a value in the range of 10 to 90°. The method for producing a light-diffusing film according to claim 1, wherein in the step (c), when viewed from above the film, the long-axis direction of the linear light source when the first active energy ray is irradiated is The acute angle θ 2 formed along the imaginary line in the moving direction of the first coating layer is a value in the range of 10 to 80°, and in the step (e), the second activity is observed from above the film. The acute axis θ 3 of the linear light source at the time of the energy ray irradiation and the imaginary line along the moving direction of the laminated body composed of the first coating layer and the second coating layer is 10 to 80°. The value in the range. The method for producing a light-diffusing film according to claim 1, wherein in the step (e), when viewed from above the film, the long-axis direction of the linear light source when the first active energy ray is irradiated The long-axis direction of the linear light source at the time of the second active energy ray irradiation is line symmetrical with respect to the imaginary line orthogonal to the moving direction of the laminated body composed of the first coating layer and the second coating layer. The method for producing a light-diffusing film according to claim 1, wherein in the step (c) and the step (e), the first activity is performed through a light-shielding plate having a long groove-shaped active energy ray transmitting portion. The energy ray is irradiated and the second active energy ray is irradiated, and the longitudinal direction of the active energy ray transmitting portion is a direction parallel to the long axis direction of the linear light source. The method for producing a light-diffusing film according to claim 1, wherein in the step (c), the peak illuminance of the surface of the first coating layer when the first active energy ray is irradiated is 0.1 A value in the range of ~50 mW/cm ² and the integrated light amount on the surface of the first coating layer is a value in the range of 5 to 300 mJ/cm ² . The method for producing a light-diffusing film according to claim 1, wherein in the step (e), the peak illuminance of the surface of the second coating layer when the second active energy ray is irradiated is 0.1~ A value in the range of 50 mW/cm ² and a cumulative light amount on the surface of the second coating layer is a value in the range of 5 to 300 mJ/cm ² . The method for producing a light-diffusing film according to claim 1, wherein in the step (b), the film thickness of the first coating layer is in a range of 80 to 700 μm , and In the step (d), the film thickness of the second coating layer is set to a value in the range of 80 to 700 μm . The method for producing a light-diffusing film according to the first aspect of the invention, wherein the moving speed of the first coating layer in the step (c) and the first coating layer in the step (e) The moving speed of the laminate comprising the second coating layer is a value in the range of 0.1 to 10 m/min.