JP2000047008A - Double-sided lenticular lens sheet and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-sided lenticular lens sheet which has excellent optical properties without deformation of the lens shape due to polymerization shrinkage of the active energy ray-curable composition and free from optical defects such as glare. I do. SOLUTION: In a double-sided lenticular lens sheet in which a lens portion composed of a lenticular lens unit is formed on both surfaces of a transparent base material by an active energy ray-curable resin, a relaxation layer having a thickness of 10 to 1000 μm is provided on the transparent base material. A double-sided lenticular lens sheet on which a number of lens units are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a double-sided lenticular lens sheet used for a projection screen used as a screen of a projection television, a microfilm reader, or the like. TECHNICAL FIELD The present invention relates to an excellent double-sided lenticular lens sheet free from defects and a method for producing such a double-sided lenticular lens sheet.

[0002]

2. Description of the Related Art In a projection screen such as a projection television or a microfilm reader, a lenticular lens sheet having lenticular lenses formed on both sides is used in order to obtain a good image. Conventionally, such a lenticular lens sheet uses a transparent resin material such as an acrylic resin, a polycarbonate resin, a vinyl chloride resin, and a styrene resin, and a method of injection-molding these resins, by bringing a resin plate into contact with a lens mold. A press molding method of transferring a lens-type lenticular lens pattern by heating and pressurizing this is known.

However, in the injection molding method, it is difficult to form a large-sized lenticular lens sheet, and it can be used only for forming a relatively small-sized lenticular lens sheet. In addition, in the press molding method, a long time is required for the heating and cooling cycle of the resin plate and the lens mold, so that a large number of lens molds are required for mass production of lenticular lens sheets, and in order to manufacture a large lenticular lens sheet. Requires enormous costs for production equipment.

On the other hand, there has been proposed a method of injecting an active energy ray-curable resin into a plate-shaped lens mold and then irradiating the active energy ray to cure the resin. Although the method using the curable resin can shorten the molding time and improve the productivity, it has problems such as entrapment of bubbles when injecting the resin liquid into the lens mold. However, it is necessary to employ a method of separately performing defoaming treatment or slowly injecting the solution, which has not been sufficient for mass production. In particular, depending on the lens-shaped pattern shape, the bubbles are trapped in the grooves, so that the bubbles are likely to be generated, and the bubbles once generated cannot be easily removed, leading to a lens defect caused by the bubbles. Had.

As a method for preventing the generation of such bubbles, as described in JP-A-1-192529, an ultraviolet curable resin is supplied to a lens mold so as to form a resin pool, and then the resin pool is formed. A method has been proposed in which a base film is placed on a base film, the resin is leveled on a lens mold with a pressure roll through the base film, the base film is laminated, and the resin is irradiated with ultraviolet rays to be cured and removed.

[0006]

However, in such a method, it is necessary to laminate the base film while keeping the distance between the pressure roll and the lens mold constant, and a lens having a uniform thickness is required. It is difficult to obtain a sheet, which causes problems such as uneven thickness of the lens sheet and deterioration of lens quality such as image distortion. In addition, since the liquid monomer composition is directly polymerized and cured and shaped, the polymerization shrinkage of the monomer during curing is large, so that the lens shape is not accurately transferred, and a lens as designed cannot be obtained. There have been problems such as distortion of the lens, generation of a minute gap between the lens portion and the sheet-shaped transparent substrate, and easy separation.

Particularly, in the case of a double-sided lenticular lens sheet, unevenness in the thickness of the lens and misalignment of the axis adversely affect the screen characteristics. It must be done accurately. In addition, the demand for higher definition of images is increasing, and in order to cope with the fine pitch of the lenticular lens, Japanese Patent Application Laid-Open Nos. 1-159627 and 3-64701 disclose an ultraviolet curable composition. A method has been proposed in which a lenticular lens is continuously formed on both surfaces of a transparent substrate using a cylindrical lens mold.

However, when a double-sided lenticular lens sheet is manufactured from such an ultraviolet-curable composition, the lens shape is slightly deformed due to polymerization shrinkage when the ultraviolet-curable composition is polymerized and cured. This causes glare, which is considered to be caused by unevenness in the reflection direction of the light.
This glare causes an optical defect, and has a problem of deteriorating optical characteristics of a screen or the like.

Therefore, an object of the present invention is to suppress deformation of a lens shape due to polymerization shrinkage of an active energy ray-curable composition such as ultraviolet rays during the production of a double-sided lenticular lens sheet, and to provide an excellent lens having no optical defects such as glare. Another object of the present invention is to provide a double-sided lenticular lens sheet having improved optical characteristics and a method for manufacturing such a double-sided lenticular lens sheet.

[0010]

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present inventors have studied the structure and manufacturing method of a double-sided lenticular lens sheet.
By providing a relaxation layer of a specific thickness on a transparent substrate,
It has been found that deformation of the lens shape due to polymerization shrinkage of the active energy ray-curable composition can be reduced.

That is, the double-sided lenticular lens sheet of the present invention is a double-sided lenticular lens sheet comprising a transparent substrate and a lens portion composed of a lenticular lens unit formed on both sides of an active energy ray-curable resin. A lenticular lens unit is formed via a relaxation layer having a thickness of 5 to 1000 μm. In addition, the method for producing a double-sided lenticular lens sheet of the present invention includes the step of forming an active energy ray-curable composition between a lens pattern forming surface of a first lens type having a first lenticular lens pattern formed thereon and a transparent substrate. Injecting step, step of uniformizing the thickness of the active energy ray-curable composition with a nip roll arranged on the outer surface side of the transparent substrate, irradiating the active energy ray through the transparent substrate with the active energy ray-curable composition Curing the first lenticular lens on one surface of the transparent substrate, and forming an active layer between the second lenticular lens pattern-formed lens pattern forming surface on which the second lenticular lens pattern is formed and the transparent substrate. Step of injecting the energy ray-curable composition, uniformizing the thickness of the active energy ray-curable composition with a nip roll disposed on the outer surface side of the transparent substrate. A method for producing a double-sided lenticular lens sheet, comprising the steps of: irradiating an active energy ray through a transparent substrate to cure an active energy ray-curable composition to form a second lenticular lens on the other surface of the transparent substrate. ,
The thickness of the active energy ray-curable composition is made uniform by adjusting the nip pressure of the nip roll by a pressure adjusting mechanism to form a relaxation layer.

According to the invention, the thickness of the active energy ray-curable composition is made uniform by adjusting the nip pressure of the nip roll by a pressure adjusting mechanism, and a relaxation layer is formed on a transparent substrate. The deformation of the lens shape due to polymerization shrinkage during curing of the line-curable composition can be mitigated by the formed relaxation layer, the reflection direction of external light is suppressed from becoming uneven, and optical defects such as glare are reduced. The present invention can provide a double-sided lenticular lens sheet having excellent optical characteristics.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a double-sided lenticular lens sheet of the present invention will be described with reference to FIG. In the figure, (a) and (b) are examples in which the shapes of the lenticular lenses formed on the exit surface side are different. (A)
Is a light-absorbing layer formed in a valley between lenticular lens units formed on the exit surface side. (B) shows a configuration in which a convex portion is formed between the lens units formed on the exit surface side, and a light absorbing layer is formed on the upper surface of the convex portion.

As shown in FIG. 1, a double-sided lenticular lens sheet of the present invention
The first lens portion 3 on which the double-sided lenticular lens unit is formed is formed of an active energy ray-curable resin,
A second lens unit 4 having a second lenticular lens unit formed on the other surface is formed of an active energy ray-curable resin, and is relaxed between the transparent substrate 2 and the first and second lens units 3 and 4. Layer 1 is formed. The relaxation layer 1
It is provided between the transparent substrate 2 and the valley of the lens unit, and is usually formed integrally with the lens portions 3 and 4 from the same active energy ray curable resin. This relaxation layer 1
By forming in the range of thickness 5 to 1000 μm,
The deformation of the lens shape due to polymerization shrinkage during curing of the active energy ray-curable composition can be suppressed. If the thickness of the relaxation layer 1 is less than 5 μm, the deformation of the lens shape due to polymerization shrinkage in the relaxation layer tends to be unable to be sufficiently relaxed. Conversely, if it exceeds 1000 μm, the thickness unevenness of the relaxation layer is controlled. And the optical characteristics tend to deteriorate due to uneven thickness. The thickness of the relaxation layer 1 is preferably 1
The range is from 0 to 500 μm, and more preferably from 15 to 500 μm.
The range is 100 μm.

In the double-sided lenticular lens sheet of the present invention, the thickness of the lens portions 3 and 4 is 50 to 1000 μm.
m, and the pitch of the lens unit is preferably about 50 to 1000 μm. In particular, the present invention in which a lenticular lens is formed of an active energy ray-curable resin is suitable for a fine-pitch double-sided lenticular lens sheet, and the lens unit pitch is 50 to 500 μm.
It is preferably in the range of, more preferably 50 to
The range is 400 μm.

The transparent substrate 2 constituting the double-sided lenticular lens sheet of the present invention is not particularly limited as long as it is a material that transmits active energy rays such as ultraviolet rays and electron beams, and a flexible glass plate or the like is used. Although a transparent resin sheet or film of a polyester resin, an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polymethacrylimide resin, or the like is preferable. In particular, those made of polymethyl methacrylate having a low surface reflectance, a mixture of polymethyl acrylate and polyvinylidene fluoride-based resin, polycarbonate-based resin, and polyester-based resin such as polyethylene terephthalate are preferable. The thickness of the transparent substrate 2 is 50 μm
A range of about 5 mm is used. In order to improve the adhesion between the lens portions 3 and 4 made of active energy ray-curable resin and the transparent substrate 2, the surface of the transparent substrate 2 is subjected to an adhesion improving treatment such as an anchor coating treatment. Are preferred.

The active energy ray-curable resin forming the relaxation layer 1 and the lens portions 3 and 4 is not particularly limited as long as it is cured with active energy rays such as ultraviolet rays and electron beams. And (meth) acrylate resins such as polyesters, epoxy resins, polyester (meth) acrylate, epoxy (meth) acrylate, and urethane (meth) acrylate.
Among them, (meth) acrylate resins are particularly preferable from the viewpoint of their optical characteristics and the like. As the active energy ray-curable composition used for such a cured resin, polyhydric acrylate and / or polyhydric methacrylate (hereinafter, referred to as polyhydric (meth) acrylate) in terms of handleability, curability, and the like. , Monoacrylate and / or monomethacrylate (hereinafter, referred to as mono (meth) acrylate), and a photopolymerization initiator using active energy rays as a main component are preferable. Representative polyvalent (meth) acrylates include polyol poly (meth) acrylate, polyester poly (meth) acrylate, epoxy poly (meth) acrylate, urethane poly (meth) acrylate, and the like. These are used alone or as a mixture of two or more. Examples of the mono (meth) acrylate include a mono (meth) acrylate of a monoalcohol and a mono (meth) acrylate of a polyol. In the latter case, the influence of free hydroxyl groups is considered. It seems that the mold release property from the metal mold deteriorates, so it is better not to use a large amount when using the metal mold. Also, since (meth) acrylic acid and its metal salt have high polarity, it is better not to use a large amount when using a metal type.

Next, a method of manufacturing a lens sheet according to the present invention will be described with reference to FIG. 5 and 5 'in the figure are lens molds having a lens pattern in which lenticular lens units are engraved, such as aluminum, brass, metal such as steel, silicone resin, polyurethane resin, epoxy resin, ABS resin, A resin mold made of a synthetic resin such as a fluorine resin or a polymethylpentene resin, an electroforming mold manufactured by Ni electroforming, or the like is used. In particular, in the case of a roll type as shown in FIG. 2, it is desirable to use a metal type from the viewpoint of heat resistance and strength. In the present invention, the shape is not limited to the roll type, and may be a flat type flat plate.
In the case of a roll mold, as shown in FIG. 3, a thin plate mold 13 on which a lens pattern is formed may be wound around a cylindrical roll 14 and fixed. In order to form the relaxation layer 1 uniformly, a thin plate stepped lens mold 18 having a thick portion at the end as shown in FIG.
It is preferable to use a cylindrical stepped lens mold that is wound around a cylindrical roll 14 and fixed. It is preferable to apply plating such as copper or nickel to the surface of such a lens mold in order to prevent various types of corrosion. Further, in order to make the cutting material particles uniform and fine, it is also possible to form a thick plating of copper, nickel or the like and form a lens pattern on the plating layer portion.

A transparent substrate 7 is supplied to the first lens mold 5 along the lens pattern forming surface, and a first active energy ray is provided between the first lens mold 5 and the transparent substrate 7. The curable composition 8 is continuously supplied from the resin tank 10. A nip roll 6 for making the thickness of the supplied first active energy ray-curable composition 8 uniform is provided outside the transparent substrate 7. As the nip roll 6, a metal roll, a rubber roll, or the like is used. In order to make the thickness of the first active energy ray-curable composition 8 uniform, it is preferable that the nip roll 6 is processed with high accuracy in terms of roundness, surface roughness, and the like. In this case, a rubber having a high hardness of 60 degrees or more is preferable. The nip roll 6 is operated by a pressure adjusting mechanism 9 to enable accurate adjustment of the thickness of the active energy ray-curable composition 8. The pressure adjusting mechanism 9 includes a hydraulic cylinder,
Although a pneumatic cylinder and various screw mechanisms can be used, a pneumatic cylinder is preferable from the viewpoint of simplicity of the mechanism.
The air pressure is controlled by a pressure regulating valve or the like.

After the first active energy ray-curable composition 8 is supplied between the first lens mold 5 and the transparent substrate 7, the first
Of the active energy ray-curable composition 8 of the first lens mold 5
An active energy ray is irradiated from an active energy ray irradiation device 12 through the transparent substrate 7 in a state sandwiched between the transparent substrate 7 and the first active energy ray-curable composition 8 to polymerize and cure the lens. The lens pattern formed on the mold is transferred to form a first lenticular lens on one surface of the transparent substrate 7. As the active energy ray irradiation device 12, a chemical lamp for chemical reaction, a low-pressure mercury lamp,
A high-pressure mercury lamp, a metal halide lamp, a visible light halogen lamp, or the like is used. It is preferable that the irradiation amount of the active energy ray is set so that the integrated energy at a wavelength of 200 to 600 nm is 0.1 to 50 J / cm ² . The active energy ray irradiation atmosphere may be air or an inert gas atmosphere such as nitrogen or argon.

Next, the transparent substrate 7 having a lenticular lens formed on one surface is supplied so that the other surface thereof comes into contact with the lens pattern forming surface of the second lens mold 5 '. Similarly, the second lens mold 5 ′ and the transparent substrate 7
During this time, the second active energy ray-curable composition 8 'is continuously supplied from the resin tank 10'. A nip roll 6 ′ operated by a pressure adjusting mechanism 9 ′ for making the thickness of the supplied second active energy ray-curable composition 8 ′ uniform is provided outside the transparent substrate 7. .
After supplying the second active energy ray-curable composition 8 ′ between the second lens mold 5 ′ and the transparent substrate 7, the second active energy ray-curable composition 8 ′ becomes the second lens mold In the state sandwiched between 5 ′ and the transparent base material 7, an active energy ray is irradiated from the active energy ray irradiation device 12 ′ through the transparent base material 7 to form the second active energy ray-curable composition 8 ′. The lens pattern formed into a lens mold by polymerization and curing is transferred, and a second lenticular lens is formed on one surface of the transparent substrate 7.

The active energy ray-curable compositions 8, 8 'supplied between the lens molds 5, 5' and the transparent substrate 7 may be maintained at a constant viscosity in order to form a uniform relaxation layer. preferable. The viscosity range varies depending on the thickness of the relaxation layer to be formed, but generally ranges from 20 to 3000 mPa · S.
And more preferably in the range of 100 to 1000 mPa · S. When the viscosities of the active energy ray-curable compositions 8 and 8 ′ are less than 20 mPa · S, it is necessary to set the nip pressure to be extremely low or to extremely increase the molding speed for forming the relaxation layer. . However, when the nip pressure is extremely reduced, the pressure adjusting mechanisms 9 and 9 ′ tend to be unable to operate stably.
It tends to cause unevenness in the thickness of the relief layer. Further, when the molding speed is extremely increased, the irradiation amount of the active energy ray is insufficient, and the curing of the active energy ray-curable compositions 8, 8 'tends to be insufficient. On the other hand, when the viscosities of the active energy ray-curable compositions 8 and 8 ′ exceed 3000 mPa · S, the curable composition 8 does not sufficiently spread to the details of the lens patterns of the lens molds 5 and 5 ′, and the lens shape is not accurately determined Transfer tends to be difficult, defects due to the incorporation of bubbles tend to occur, and productivity tends to deteriorate due to an extremely low molding speed. In order to maintain the viscosity of the active energy ray-curable compositions 8, 8 'at a constant level, the temperature of the curable compositions 8, 8' can be controlled so that the outside of the resin tanks 10, 10 'can be controlled. It is preferable to install heat source equipment such as a sheath heater and a hot water jacket inside.

The lens sheet of the present invention is prepared by controlling the pressure of the nip rolls 6 and 6 ′ and the viscosity of the active energy ray-curable compositions 8 and 8 ′ by the above-described production method. In order to make the thicknesses of the compositions 8 and 8 'uniform and to irradiate active energy rays with the relaxation layer formed, the lens shape due to polymerization shrinkage during polymerization and curing of the active energy ray-curable compositions 8, 8' Can be reduced by the relaxation layer.

[0024]

The present invention will be described below in more detail with reference to examples. Example 1 As shown in FIG.
Pitch 7 on the surface of 790 mm JIS brass thin sheet
A first thin plate lens mold 13 having an 80 μm emission surface lenticular lens shape was prepared. The first thin plate lens mold 13 was subjected to electroless nickel plating to prevent various types of corrosion. Next, in order to fix the thin plate lens mold 13,
A stainless steel cylindrical roll 14 having a diameter of 250 mm and a length of 1000 mm is prepared, the first thin plate lens mold 13 is wound around the circumference of the cylindrical roll 14 and fixed with screws, and the first cylindrical lens mold 5 is removed. Obtained. Similarly, pitch 780
2nd stamped lenticular lens shape
Was prepared to obtain a second cylindrical lens mold 5 ′.

As shown in FIG. 4, the cylindrical lens mold 5,
NBR rubber rolls 6 and 6 'having a rubber hardness of 80 degrees were arranged close to 5'. The first cylindrical lens mold 5 and the first
A 500 μm thick polycarbonate film 7 slightly larger than the first cylindrical lens mold 5 between the rubber roll 6 and
Is passed along the first cylindrical lens mold 5 and the first pneumatic cylinder 9 connected to the first rubber roll 6 causes the first
Was nipped between the rubber roll 6 and the first cylindrical lens mold 5. At this time, the operating pressure of the first pneumatic cylinder 9 was 0.1 MPa. As the first pneumatic cylinder 9, an SMC air cylinder having an air tube diameter of 32 mm was used. Further, a first ultraviolet irradiation device 12 was provided below the first cylindrical lens mold 5. The first ultraviolet irradiation device 12 has an ultraviolet intensity of 120 W / cm, and is composed of an ultraviolet irradiation lamp manufactured by Western Quartz, having a capacity of 9.6 kW, a cold mirror type parallel light reflector, and a power supply. The first ultraviolet-curable composition 8 was prepared by mixing a refractive index adjusting component, a catalyst, and the like in advance, and was charged into the first resin tank 10. In the first resin tank 10, all parts in contact with the first ultraviolet curable composition 8 are SUS3
04. Further, in order to control the liquid temperature of the first ultraviolet curable composition 8 to 40 ° C. ± 1 ° C., a warm water jacket layer is provided, and the warm water adjusted to 40 ° C. by the first temperature controller 15 is used. Supply to the warm water jacket layer, and the resin tank 1
The liquid temperature of the ultraviolet-curable composition 8 within 0 was kept constant. Further, the bubbles generated at the time of charging were defoamed and removed by bringing the first resin tank 10 into a vacuum state by the first vacuum pump 16.

The first UV-curable composition 8 was as follows, and the viscosity was adjusted to 600 mPa · S / 25 ° C. Phenoxyethyl acrylate 45 parts by weight (Biscoat # 192 manufactured by Osaka Organic Chemical Industry Co., Ltd.) 55 parts by weight of bisphenol A-diepoxy-acrylate (Epoxyester 3000A manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.) 2-hydroxy-2-methyl-1-phenyl-propane -1-one (Darocur 1173 manufactured by Ciba-Geigy) 1.5 parts by weight Once the inside of the first resin tank 10 is returned to normal pressure and the tank is sealed, 0.02 MPa is supplied into the first resin tank 10.
The first UV curable composition 8 is passed through a first pipe 17 whose temperature is controlled by applying air pressure of 1 and opening a valve at the lower part of the first resin tank 10, and the first temperature-controlled first pipe 17 is also opened. From the supply nozzle 11 on the polycarbonate film 7 which is nipped between the first rubber roll 6 and the first cylindrical lens mold 5. First supply nozzle 1
1 is MN-18-G13 manufactured by Iwashita Engineering Co., Ltd.
An AV101 valve manufactured by the company equipped with a needle was used. Mitsubishi Electric 0.2kW geared motor (reduction ratio 1
/ 200), while rotating the first cylindrical lens mold 5 at a speed of 2.0 m / min, the first ultraviolet-curable composition 8 is sandwiched between the first cylindrical lens mold 5 and the polycarbonate film 7. In this state, ultraviolet rays were irradiated from the first ultraviolet irradiation device 12 to polymerize and cure the first ultraviolet-curable composition 8 to form an emission surface lenticular lens on one surface of the polycarbonate film 7.

Next, a polycarbonate film 7 having an exit surface lenticular lens formed on one surface is placed on a second surface.
Is supplied along the second cylindrical lens mold 5 ′ so that the other surface of the polycarbonate film 7 abuts between the cylindrical lens mold 5 ′ and the second rubber roll 6 ′. The polycarbonate film 7 was nipped between the second rubber roll 6 'and the second cylindrical lens mold 5' by the connected second pneumatic cylinder 9 '. At this time, the operating pressure of the second pneumatic cylinder 9 'is 0.1 MPa.
Met. The second UV-curable composition 8 ′, which is the same as the first UV-curable composition 8, is prepared by previously mixing a refractive index adjusting component, a catalyst, and the like, and then preparing a second resin tank 10 ′.
It was put in. Further, bubbles generated at the time of charging were defoamed and removed by bringing the second resin tank 10 'into a vacuum state by the second vacuum pump 16'.

Once the inside of the second resin tank 10 ′ is returned to normal pressure and the tank is closed, an air pressure of 0.02 MPa is applied to the inside of the second resin tank 10 ′,
By opening the valve at the bottom of 0 ′, the second ultraviolet-curable composition 8 ′ is supplied to the second temperature-controlled second pipe 17 ′.
Through the second supply nozzle 11 ′, which is also temperature-controlled.
From the second rubber roll 6 'and the second cylindrical lens mold 5'. While rotating the second cylindrical lens mold 5 'at a speed of 2.0 m / min with a Mitsubishi Electric 0.2 kW geared motor (reduction ratio 1/200), the second ultraviolet curable composition 8' The second ultraviolet irradiation device 1 is sandwiched between the cylindrical lens mold 5 ′ and the polycarbonate film 7.
UV light was irradiated from 2 ′ to polymerize and cure the second UV-curable composition 8 ′ to form an incident surface lenticular lens on one surface of the polycarbonate film 7. Thereafter, the mold was released from the second cylindrical lens mold 5 'to obtain a double-sided lenticular lens sheet.

Both lens cross sections of the obtained lenticular lens sheet were scanned with a scanning electron microscope (JS JS
(M-840A, 2000 times), a relaxation layer having a thickness of 20 μm was formed between the polycarbonate film 7 and the lenticular lens valley, and almost no deformation of the lens shape due to polymerization shrinkage was observed. Met. Further, the obtained double-sided lenticular lens sheet was subjected to an optical microscope (SMZ-2T manufactured by Nikon Corporation, magnification: 40).
), And gradually tilted the lens sheet while applying light to the lens surface, and confirmed the reflected light on the lens surface. As a result, no optical defects such as glare were observed, and the optical characteristics were excellent.

Example 2 As shown in FIG. 5, the thickness was 2.0 mm, 1000 mm ×
A first thin plate stepped lens mold 18 is prepared by engraving a 350 μm pitch emission surface lenticular lens on a JIS brass three thin plate having a size of 790 mm and a portion excluding 10 mm from both ends thinned by 0.04 mm from both ends. did. The first thin plate lens mold 18 was subjected to electroless nickel plating to prevent various types of corrosion. Next, in order to fix the first thin plate stepped lens mold 13, the diameter is 250 mm and the length is 10 mm.
Prepare a cylindrical roll 14 made of stainless steel of 00 mm,
A first thin plate stepped lens mold 13 was wound around the circumference of the cylindrical roll 14 and fixed with screws to obtain a first cylindrical stepped lens mold 19. In the same manner, a second thin plate stepped lens mold 13 ′ engraved with a 350 μm pitch incident surface lenticular lens shape was prepared, and a second cylindrical stepped lens mold 19 ′ was obtained.

As shown in FIG. 6, the metal rolls 20, 20 'are positioned close to the cylindrical stepped lens molds 19, 19'.
(Obtained by shaving a SUS400 round bar and subjecting it to hard chrome plating). Between the first cylindrical stepped lens mold 19 and the first metal roll 20, a thickness 188 μm slightly larger than the first cylindrical stepped lens mold 19.
Of the polyethylene terephthalate film 7 along the first cylindrical stepped lens mold 19 and the first metal roll 2
The polyethylene terephthalate film 7 was nipped between the first metal roll 20 and the first cylindrical stepped lens mold 19 by the first pneumatic cylinder 9 connected to the first pneumatic cylinder 9.
At this time, the operating pressure of the first pneumatic cylinder 9 is 0.1 M
Pa. As the first pneumatic cylinder 9, an SMC air cylinder having an air tube diameter of 32 mm was used. Further, the first ultraviolet irradiation device 12 was installed below the first cylindrical stepped lens mold 19. The first ultraviolet irradiation device 12 has an ultraviolet intensity of 120 W / cm, and is composed of an ultraviolet irradiation lamp manufactured by Western Quartz, having a capacity of 9.6 kW, a cold mirror type parallel light reflector, and a power supply. The first ultraviolet-curable composition 8 was prepared by mixing a refractive index adjusting component, a catalyst, and the like in advance, and was charged into the first resin tank 10. In the first resin tank 10, all parts in contact with the first ultraviolet curable composition 8 were SUS304. Further, the liquid temperature of the first ultraviolet curable composition 8 is set to 40
In order to control the temperature to 1 ° C. ± 1 ° C., a warm water jacket layer is provided. Hot water adjusted to 40 ° C. by the first temperature controller 15 is supplied to the warm water jacket layer, and the first resin tank 10
The liquid temperature of the first UV-curable composition 8 was kept constant.
Further, the bubbles generated at the time of charging were defoamed and removed by bringing the first resin tank 10 into a vacuum state by the first vacuum pump 16.

The first UV-curable composition 8 was as follows, and the viscosity was adjusted to 600 mPa · S / 25 ° C. Phenoxyethyl acrylate 45 parts by weight (Biscoat # 192 manufactured by Osaka Organic Chemical Industry Co., Ltd.) 55 parts by weight of bisphenol A-diepoxy-acrylate (Epoxyester 3000A manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.) 2-hydroxy-2-methyl-1-phenyl-propane -1-one (Darocur 1173 manufactured by Ciba-Geigy) 1.5 parts by weight Once the inside of the first resin tank 10 is returned to normal pressure and the tank is sealed, 0.02 MPa is supplied into the first resin tank 10.
The first UV curable composition 8 is passed through a first pipe 17 whose temperature is controlled by applying air pressure of 1 and opening a valve at the lower part of the first resin tank 10, and the first temperature-controlled first pipe 17 is also opened. From the supply nozzle 11 to the first metal roll 20
And a first cylindrical stepped lens mold 19, which was nipped between the polyethylene terephthalate films 7. As the first supply nozzle 11, an AV101 valve manufactured by Iwashita Engineering Co., Ltd. equipped with a MN-18-G13 needle was used. While rotating the first cylindrical stepped lens mold 19 at a speed of 2.0 m / min with a Mitsubishi Electric 0.2 kW geared motor (reduction ratio 1/200),
In a state where the first ultraviolet curable composition 8 is sandwiched between the first cylindrical stepped lens mold 19 and the polyethylene terephthalate film 7, the first ultraviolet ray is irradiated from the first ultraviolet ray irradiating device 12 to the first ultraviolet ray. The curable composition 8 was polymerized and cured to form an exit surface lenticular lens on one surface of the polyethylene terephthalate film 7.

Next, the polyethylene terephthalate film 7 having an exit surface lenticular lens formed on one surface is placed between the second cylindrical stepped lens mold 19 ′ and the second metal roll 20 ′. Are supplied along the second cylindrical stepped lens mold 19 ′ so that the surfaces of the second metal roll 20 ′ and the second metal roll 20 ′ are connected by the second pneumatic cylinder 9 ′ connected to the second metal roll 20 ′. The polyethylene terephthalate film 7 was nipped between the second cylindrical stepped lens molds 19 '. At this time, the operating pressure of the second pneumatic cylinder 9 'was 0.1 MPa. The second UV-curable composition 8 ′, which is the same as the first UV-curable composition 8, was previously mixed with a refractive index adjusting component, a catalyst, and the like, and was charged into a second resin tank 10 ′. . Further, the foam generated at the time of charging is discharged to the second resin tank 1 by the second vacuum pump 16 '.
The inside of 0 ′ was evacuated and evacuated by applying a vacuum.

Once the inside of the second resin tank 10 ′ is returned to normal pressure and the tank is closed, an air pressure of 0.02 MPa is applied to the inside of the second resin tank 10 ′,
By opening the valve at the bottom of 0 ′, the second ultraviolet-curable composition 8 ′ is supplied to the second temperature-controlled second pipe 17 ′.
Through the second supply nozzle 11 ′, which is also temperature-controlled.
From the second metal roll 20 'and the polyethylene terephthalate film 7 which is nipped between the second cylindrical stepped lens mold 19'. 0.2kW made by Mitsubishi Electric
While rotating the second cylindrical stepped lens mold 19 ′ at a speed of 2.0 m / min with a geared motor (reduction ratio 1/200), the second ultraviolet-curable composition 8 ′ is supplied to the second cylindrical step. The second ultraviolet irradiation device 12 ′ is sandwiched between the attached lens mold 19 ′ and the polyethylene terephthalate film 7.
Then, the second ultraviolet-curable composition 8 ′ was polymerized and cured to form an incident surface lenticular lens on one surface of the polyethylene terephthalate film 7.
Thereafter, the mold is released from the second cylindrical stepped lens mold 19 ′,
A double-sided lenticular lens sheet was obtained.

Both lens sections of the obtained lenticular lens sheet were scanned with a scanning electron microscope (JS JS
(M-840A, 2000 times), a relaxation layer having a thickness of 30 μm was formed between the polyethylene terephthalate film 7 and the lenticular lens valley, and almost no deformation of the lens shape due to polymerization shrinkage was observed. Was something. Further, the obtained double-sided lenticular lens sheet was placed on an optical microscope (Nikon SMZ-2T,
(Magnification: 40 ×), the lens sheet was gradually tilted while irradiating the lens surface with light, and reflected light on the lens surface was confirmed. As a result, no optical defects such as glare were observed, and the optical characteristics were excellent.

Comparative Example 1 Using the same apparatus as in Example 1, the molding conditions were such that the operating pressure of the pneumatic cylinders 9 and 9 'was 0.1 MPa,
A double-sided lenticular lens sheet was obtained in the same manner as in Example 1, except that the following compositions were used as the ultraviolet-curable compositions 8 and 8 '. In addition, the viscosity of the ultraviolet-curable compositions 8 and 8 ′ was 15 mPa · S / 25 ° C.

90 parts by weight of phenoxyethyl acrylate (Biscoat # 192 manufactured by Osaka Organic Chemical Industry Co., Ltd.) 10 parts by weight of bisphenol A-diepoxy-acrylate (Epoxyester 3000A manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.) 2-hydroxy-2-methyl-1- Phenyl-propan-1-one (Darocur 1173, Ciba-Geigy) 1.5 parts by weight A scanning electron microscope (JSM-84, manufactured by JEOL Ltd.) was used to examine both lens cross sections of the obtained double-sided lenticular lens sheet.
(0A, 2000 times), no relaxation layer was formed between the polycarbonate film 7 and the lenticular lens, and it was found that the lenticular lens surface was slightly deformed. Furthermore, the obtained double-sided lenticular lens sheet is placed on an optical microscope (SMZ-2T, manufactured by Nikon Corporation, magnification: 40 ×), and the lens sheet is gradually tilted while applying light to the lens surface, and the reflected light on the lens surface is reflected. It was confirmed. As a result, it was confirmed that the light reflection timing was different at the same portion of each lens row. As a result, optical defects such as glare occurred, and the optical characteristics were poor.

[0038]

The present invention provides a lens sheet having lenticular lens units formed on both sides of a transparent base material by an active energy ray-curable resin, by forming a relaxation layer having a specific thickness on the transparent base material. By alleviating the deformation of the lens shape due to the polymerization shrinkage of the line-curable composition, it is possible to provide a double-sided lenticular lens sheet having excellent optical properties without occurrence of optical defects such as spot-like patterns.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a lens sheet of the present invention.

FIG. 2 is a schematic diagram showing a manufacturing process of the present invention.

FIG. 3 is a schematic view showing a cylindrical lens mold of the present invention.

FIG. 4 is a schematic diagram showing a specific manufacturing process of the present invention.

FIG. 5 is a schematic diagram showing a cylindrical stepped lens mold of the present invention.

FIG. 6 is a schematic diagram showing another specific manufacturing process of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Relaxation layer 2 Transparent base material 3 1st lens part 4 2nd lens part 5, 5 'Cylindrical lens type 6, 6' Nip roll 7 Transparent base material 8, 8 'Active energy ray-curable composition 9, 9' Pressure adjusting mechanism 10, 10 'Resin tank 11, 11' Supply nozzle 12, 12 'Active energy ray irradiation device 13, 13' Thin plate lens type 14, 14 Cylindrical roll 15, 15 'Temperature controller 16, 16' Vacuum pump 17, 17 'Piping 18, 18' Thin plate stepped lens type 19, 19 'Cylindrical stepped lens type 20, 20' Metal roll

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) G03B 21/62 G03B 21/62 (72) Inventor Yukichi Konami 4-160 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon F-term in Product Development Laboratory Co., Ltd. (reference) 2H021 BA23 BA28 BA29 BA32 2H042 AA03 AA28 BA04 BA15 BA19 4F213 AA44 AH74 WA02 WA53 WA56 WA86 WC03 WF36

Claims (4)

[Claims] 1. A double-sided lenticular lens sheet in which a lens portion composed of a lenticular lens unit is formed on both surfaces of a transparent base material by an active energy ray-curable resin, wherein a relaxation layer having a thickness of 5 to 1000 μm is provided on the transparent base material. A double-sided lenticular lens sheet, wherein a lenticular lens unit is formed through the lenticular lens unit. 2. The double-sided lenticular lens sheet according to claim 1, wherein the relaxation layer is made of an active energy ray-curable resin and is integrated with the lens portion. 3. A step of injecting an active energy ray-curable composition between a lens pattern forming surface of a first lens type having a first lenticular lens pattern formed thereon and a transparent substrate, and an outer surface of the transparent substrate. One step of uniformizing the thickness of the active energy ray-curable composition with the nip roll arranged on the side, irradiating the active energy ray through the transparent substrate to cure the active energy ray-curable composition and one of the transparent substrates Forming a first lenticular lens on the surface, injecting an active energy ray-curable composition between the transparent substrate and the lens pattern forming surface of the second lens type having the second lenticular lens pattern formed thereon Process, a step of making the thickness of the active energy ray-curable composition uniform with a nip roll arranged on the outer surface side of the transparent substrate, irradiation of the active energy ray through the transparent substrate Forming a second lenticular lens on the other surface of the transparent substrate by curing the active energy ray-curable composition to form a second lenticular lens sheet, wherein the nip pressure of the nip roll is adjusted by a pressure adjusting mechanism. A method for producing a double-sided lenticular lens sheet, wherein the thickness of the active energy ray-curable composition is made uniform to form a relaxation layer. 4. The double-sided lenticular lens sheet according to claim 3, wherein the lens mold has a cylindrical shape, and a step portion thicker than other portions is formed near an end of the cylinder. Method.