TW201921006A - Polarizing plate, manufacturing method thereof, and display device - Google Patents

Abstract

An objective of the present invention is to provide a polarizing plate capable of making streaky unevenness inconspicuous regardless of a change in hue. The polarizing plate 1 of the present invention includes a polarizer 2, and protective films 3 and 4 disposed on at least one surface of the polarizer 2 via an adhesive layer; wherein, the visibility correction monoaxial transmittance (Ty) measured in the initial state is 44% or more, the orthogonal hue measured in the initial state and after the durability test does not change sign with the a coordinate axis and the b coordinate axis between the ab chromaticity coordinates interposed there between.

Description

   Polarizing plate, manufacturing method thereof, and display device   

The present invention relates to a polarizing plate, a manufacturing method thereof, and a display device.

For example, it is proposed in the following Patent Document 1 that streaks originating from the surface of the polarizer produce streak unevenness that can be confirmed by the intensity of the reflected light. Therefore, the height of the unevenness on the surface of the polarizer is set to 280 nm Hereinafter, streak unevenness caused by the intensity of the reflected light is suppressed.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent No. 6166431

In recent years, for the purpose of reducing power consumption and the like, polarizing plates have been developed toward high transmission. On the other hand, when the polarizing plate becomes highly transmissive, as described in Patent Document 1, it is known that even if the unevenness on the surface of the polarizer is set to 280 nm or less, the unevenness caused by the unevenness on the surface of the polarizer is orthogonal. Light in a crossed nicols state penetrates the polarizer to produce uneven streaks.

In addition, with regard to polarizers with high transmission, even if the hue of the initial state is adjusted, the streaky unevenness that can be seen through the polarizer in the crossed polarized state becomes inconspicuous, but during the use of the polarizer, Stripe unevenness may be noticeable due to a change in hue (color) of the polarizing plate.

The present invention has been proposed in view of such a conventional situation, and an object thereof is to provide a polarizing plate capable of making stripe unevenness inconspicuous regardless of a change in hue, a manufacturing method thereof, and a display having such a polarizing plate. Device.

With regard to the means for solving the above-mentioned problems, according to an aspect of the present invention, it is possible to provide a polarizing plate including a polarizer and a protective film disposed on at least one side of the polarizer via an adhesive layer; Among them, the photometric correction monomer transmittance (Ty) measured in the initial state is more than 44%, and the orthogonal color tone measured in the initial state and after the endurance test is related to the a coordinate axis and the b coordinate axis in the ab color coordinate. There is no change in the area of the raised symbol.

Moreover, in the said polarizing plate, after the said durability test, it may be a structure which "starts at least from the said initial state, supplies it to a dry gas environment, and heats at 105 degreeC for 30 minutes".

In the polarizing plate, the polarizer may have a structure of "a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film stretched uniaxially".

In the polarizing plate, a thickness of the polarizer may be 3 to 15 μm.

Moreover, in the said polarizing plate, when the said protective film is removed, the structure which has the unevenness | corrugation with a height difference of 80-250 nm on the surface of the said polarizing plate to which the adhesive agent was adhered may be sufficient.

The polarizing plate may have a structure in which the polarizer is an iodine-based polarizer.

Moreover, according to one aspect of the present invention, it is possible to provide a display device including a display panel and any of the aforementioned polarizing plates.

Furthermore, according to an aspect of the present invention, it is possible to provide a method for manufacturing a polarizing plate including a polarizer and a protective film disposed on at least one side of the polarizer through an adhesive layer; and manufacturing the polarizer The method includes the following tone adjustment step: adjusting the orthogonal tone measured in the initial state and after the endurance test so that the area of the symbol raised by the a coordinate axis and the b coordinate axis in the ab chromaticity coordinate does not change.

In addition, the method for manufacturing the polarizing plate may be one in which the hue adjustment step is to adjust at least the hue of the polarizer.

In addition, the manufacturing method of the polarizing plate may be a manufacturing method of the protective film in which the hue adjusting step is selected and arranged on at least one side or both sides of the polarizing plate.

As described above, according to aspects of the present invention, it is possible to provide a polarizing plate and a flexible display device having such a polarizing plate; wherein the aforementioned polarizing plate can make the stripe non-uniform regardless of the color tone change. Become inconspicuous.

1, 1A, 1B‧‧‧‧Polarizer

2‧‧‧ polarizer

3, 4‧‧‧ protective film

5‧‧‧ Adhesive layer

10‧‧‧ display device

11‧‧‧Display Panel

30 to 41‧‧‧Guide rollers

50 to 55‧‧‧ rolls

100‧‧‧ manufacturing equipment

101‧‧‧ Raw Roll

102‧‧‧Swelling bath

103‧‧‧ Dyeing bath

104‧‧‧ Cross-linking bath

105‧‧‧washing bath

106‧‧‧ drying furnace

F‧‧‧ film

FIG. 1 is a cross-sectional view showing a configuration of a polarizing plate according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing the structure of a polarizing plate according to another embodiment of the present invention.

Fig. 3 is a cross-sectional view showing the structure of a polarizing plate according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a display device including the polarizing plate shown in FIG. 2.

FIG. 5 is an ab chromaticity coordinate graph for explaining changes in orthogonal hue measured before and after the endurance test of the polarizing plate.

FIG. 6 is a schematic diagram showing a configuration of a manufacturing apparatus for a polarizing film.

Fig. 7 is a graph showing ab chromaticity coordinates of the orthogonal tone change measured before and after the endurance test in Examples 1 and 2.

FIG. 8 shows the ab chromaticity coordinate graphs of the orthogonal tone change measured before and after the endurance test in Examples 3 and 4, and Comparative Examples 1 and 2. FIG.

FIG. 9 shows the ab chromaticity coordinate graph of the orthogonal tone change measured before and after the endurance test in Reference Example 1. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In addition, the drawings used in the following description are for the sake of easy viewing of the structural elements, and the structural elements may be represented in a schematic manner. The scale of the displayed size may also vary depending on the structural elements. In addition, the materials, numerical values, and the like exemplified in the following description are examples, and the present invention is not limited to these examples, and can be appropriately changed and implemented without changing the gist thereof.

(Polarizer)

First, an embodiment of the present invention will be described using, for example, the polarizing plate 1 shown in FIG. 1.

FIG. 1 is a cross-sectional view showing a schematic structure of the polarizing plate 1.

As shown in FIG. 1, the polarizing plate 1 of this embodiment includes a polarizer 2 and protective films 3 and 4 arranged on at least one side of the polarizer 2 (both sides in this embodiment), and These protective films 3 and 4 are bonded to both surfaces of the polarizer 2 (layered via an adhesive layer) via an adhesive (not shown).

The polarizer 2 has a function of converting light such as natural light into linearly polarized light, and has a transmission axis and an absorption axis. The transmission axis of the polarizer 2 is the vibration direction of the transmitted light when natural light penetrates the polarizer 2. On the other hand, the absorption axis of the polarizer 2 is a direction perpendicular to the transmission axis of the polarizer 2.

In general, the polarizer 2 is made of a polarizing film in which a uniaxially stretched polyvinyl alcohol (PVA) resin film adsorbs and orients a dichroic dye such as iodine and a dichroic dye. Therefore, the absorption axis direction of the polarizer 2 is consistent with its extension direction (MD), and the transmission axis direction of the polarizer 2 is consistent with its width direction (TD).

The PVA-based resin film is usually obtained by saponifying a polyvinyl acetate-based resin. The saponification degree is usually about 85 mol% or more, preferably about 90 mol% or more, and more preferably about 99 mol% or more.

The polyvinyl acetate-based resin may be, for example, a copolymer of vinyl acetate and other monomers copolymerizable with vinyl acetate, in addition to polyvinyl acetate, which may be a homopolymer of vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1500 to 5,000. These polyvinyl alcohol-based resins can also be modified, for example, polyvinyl acetal modified with aldehydes, polyvinyl acetal, polyvinyl butyral, and the like can be used.

From the viewpoint of thinning the polarizing plate 1, the thickness of the polarizing plate 2 is preferably thin, but it can be appropriately set depending on the application of the polarizing plate 1 and the like. The thickness of the polarizer 2 is, for example, 25 μm or less, preferably 20 μm or less, and more preferably 15 μm or less; for example, 1 μm or more, and preferably 3 μm or more. When the thickness of the polarizer 2 is 15 μm or less, wrinkles are easily generated during transportation of the PVA-based resin film, and unevenness is easily generated in the polarizer 2. Therefore, the effect of the present invention is increased. The thickness of the polarizing plate 2 in the polarizing plate 1 can be considered to be substantially the same as the thickness of the polarizing plate 2 after the protective films 3 and 4 are bonded through the adhesive and cured.

Examples of the protective films 3 and 4 include: a film made of an ethyl cellulose-based resin such as triethyl cellulose or diethyl cellulose; and a film made of polyethylene terephthalate Polyester resin film of polyester, polyethylene naphthalate and polybutylene terephthalate; polycarbonate resin film; cycloolefin resin film; acrylic resin film; made of polypropylene A film made of a resin olefinic resin.

When the protective films 3 and 4 are arranged on both sides of the polarizer 2, the protective films 3 and 4 may be made of the same kind of resin, or the protective films 3 and 4 may be made of different kinds of resin.

From the viewpoint of reducing the thickness of the polarizing plate 1, although the thickness of the protective films 3 and 4 is preferably thin, it can be appropriately set in accordance with the use of the polarizing plate 1 and the like. The thickness of the protective films 3 and 4 may be, for example, 85 μm or less, preferably 50 μm or less, and more preferably 30 μm or less.

On the other hand, from the viewpoint of processability, the thickness of the protective films 3 and 4 is preferably a thickness capable of securing a certain degree of strength, and may be, for example, 5 μm or more, and preferably 10 μm or more.

The adhesive may be an aqueous adhesive or an active energy ray-curable adhesive. Examples of the water-based adhesive include an aqueous solution of a polyvinyl alcohol-based resin, or an aqueous solution prepared with a crosslinking agent in an aqueous solution of the polyvinyl alcohol-based resin, such as an aqueous adhesive of an amine ester-based latex adhesive.

The active energy ray-curable adhesive means an adhesive that is cured by irradiating active energy rays such as ultraviolet rays or electron rays. When the active energy ray-curable adhesive is classified by its hardened form, a cationic polymerizable adhesive containing a cationically polymerizable compound that becomes a curable compound, and a radical polymerizable compound containing a curable compound can be cited. Radical polymerizable adhesives, curable adhesives containing both cationic polymerizable compounds and radical polymerizable compounds, and the like. Examples of the cationically polymerizable compound include an epoxy compound and an oxetane compound. Examples of the radical polymerizable compound include a (meth) acrylic compound having one or more (meth) acrylfluorenyl groups in a molecule.

The thickness of the adhesive layer formed by the water-based adhesive may be, for example, 20 nm or more, and preferably 40 nm or more. On the other hand, from the viewpoint of production cost and the like, the thickness of the adhesive may be more than necessary but not too thick. For example, it may be 1000 nm or less, preferably 500 nm or less, and more preferably 300 nm or less. .

The thickness of the adhesive layer formed by the active energy ray-curable adhesive is preferably 0.1 μm or more, more preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. .

Other embodiments of the present invention may have the structure of a polarizing plate 1A shown in FIG. 2 or a polarizing plate 1B shown in FIG. 3, for example. FIG. 2 is a cross-sectional view showing a simplified structure of the polarizing plate 1A. FIG. 3 is a cross-sectional view showing a schematic structure of the polarizing plate 1B.

Specifically, the polarizing plate 1A shown in FIG. 2 includes the polarizing plate 2 and the polarizing plate 2 disposed in at least one protective film (the protective film 4 in this embodiment) in addition to the structure of the polarizing plate 1 described above. The structure of the adhesive (PSA) layer 5 on the opposite side. On the other hand, the polarizing plate 1B shown in FIG. 3 has a structure including a polarizer 2, a protective film 3 arranged on one side of the polarizer 2, and an adhesive layer 5 arranged on the other side of the polarizer 2.

The adhesive layer 5 can adhere the polarizer 2 and the protective films 3 and 4 by its own adhesiveness. The adhesive for forming the adhesive layer 5 may be selected as long as it is conventionally known, and it may be an adhesive having such a degree that peeling does not occur in an environment where the polarizing plates 1A and 1B are exposed. . Specific examples include acrylic adhesives, polysiloxane adhesives, rubber adhesives, etc. In terms of transparency, weather resistance, heat resistance, and processability, acrylic adhesives are characteristic good. The thickness of the adhesive layer 5 is usually about 3 to 100 μm, and preferably 5 to 50 μm.

Moreover, in the adhesive, it can be appropriately blended as needed: a tackifier, a plasticizer, glass fiber, glass beads, metal powder, a filler made of other inorganic powder, pigment, coloring, etc. Additives, fillers, antioxidants, ultraviolet absorbers, antistatic agents, silane coupling agents and other additives.

The adhesive layer 5 is used by the user to adhere the polarizing plates 1A and 1B to other members. A release film (not shown) may be provided on the surface of the adhesive layer 5 in advance. When a release film is present on the surface of the adhesive layer 5, the release film is peeled off from one side, and this adhesive layer 5 can be bonded (laminated) to the polarizer 2 or the protective films 3 and 4. After the release film is further peeled off from the other side, it can be bonded to other members through the adhesive layer 5.

The structure of the polarizing plate to which the present invention can be applied is not necessarily limited to the structures of the polarizing plates 1, 1A, and 1B shown in FIGS. 1 to 3 described above. That is, the polarizing plate to which the present invention can be applied may be a structure including a polarizer and a protective film disposed on at least one or both sides of the polarizer, and a structure other than this structure can be appropriately added and changed. change.

For example, in the polarizing plates 1 and 1A, other functional layers such as a retardation film and a brightness enhancement film may be applied instead of the protective film 4.

When the polarizing plates 1, 1A, and 1B are used as circular polarizing plates, a structure including a 1/4 wavelength (λ / 4) plate may be used in addition to the above structure. The λ / 4 plate has the function of converting linearly polarized light of a certain wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light). The λ / 4 plate is disposed on the surface on the side opposite to the polarizer 2 of the protective film 4 through the adhesive layer 5.

When the above-mentioned polarizing plates 1, 1A, and 1B are used as circular polarizing plates, a structure including a positive C-plate in addition to a λ / 4 plate may be used. The positive C plate can reduce the change in the reflection hue (color) of the polarizing plates 1, 1A, and 1B. When a positive type C plate is included, the λ / 4 plate is preferably a λ / 4 plate with reverse wavelength dispersion. The positive C plate is disposed on the surface (the other surface) opposite to the polarizer 2 of the λ / 4 plate via an adhesive layer or an adhesive layer. Therefore, for example, in the case of the above-mentioned polarizing plate 1, it is a laminated structure having the above-mentioned polarizing plate 1, an adhesive layer 5, a λ / 4 plate, an adhesive layer or an adhesive layer, and a positive C plate.

When the above-mentioned polarizing plates 1, 1A, and 1B are used as circular polarizing plates, a structure including a 1/2 wavelength (λ / 2) plate may be used in addition to the λ / 4 plate. The λ / 2 plate is a person that can impart a phase difference of π (= λ / 2) in the direction of the electric field vibration (polarized surface) of the incident light, and has a function of changing the direction (polarization direction) of linearly polarized light. When the circularly polarized light is incident, the rotation direction of the circularly polarized light can be reversed. The λ / 2 plate is disposed on a surface (the other surface) opposite to the polarizer 2 of the λ / 4 plate via an adhesive layer or an adhesive layer. Therefore, for example, in the case of the above-mentioned polarizing plate 1, it has a laminated structure of the above-mentioned polarizing plate 1, an adhesive layer 5, a λ / 4 plate, an adhesive layer or an adhesive layer, and a λ / 2 plate.

(Display device)

Next, a display device according to this embodiment will be described with reference to FIG. 4.

FIG. 4 is a cross-sectional view showing a configuration of a display device 10 including the polarizing plate 1A shown in the above-mentioned FIG. 2.

As shown in FIG. 4, the display device 10 of this embodiment includes a display panel 11 and a polarizing plate 1A disposed on the viewing side of the display panel 11. The polarizing plate 1A is bonded to the display panel 11 through an adhesive layer as viewed 5.

The display panel 11 is not particularly limited, and may be, for example, a liquid crystal display element, an organic electroluminescence (EL) display element, or the like. When the display device 10 uses a liquid crystal display panel as the display panel 11, it is referred to as a liquid crystal display device. On the other hand, when the display device 10 uses an organic EL display element as the display panel 11, it is referred to as an organic EL display device.

The structure of the display device to which the present invention can be applied is not necessarily limited to the structure of the display device 10 shown in FIG. 4 described above. In other words, a display device to which the present invention can be applied can have appropriate changes to the structure of the display panel as long as the display device includes the polarizing plate to which the present invention can be applied. On the other hand, the application to which the polarizing plate of the present invention can be applied is not limited to the above-mentioned display device, and can be used for various optical applications.

Incidentally, the polarizing plate 1 of this embodiment adjusts the orthogonal hue measured in the initial state and after the endurance test in such a manner that the symbol area enclosed by the a coordinate axis and the b coordinate axis in the ab chromaticity coordinate does not change. . That is, the change in the orthogonal hue measured before and after the endurance test of the polarizing plate 1 is set to a value in which the a-coordinate axis and the b-coordinate axis do not cross the quadrant. Thereby, even if the orthogonal hue of the polarizing plate 1 is changed before and after the endurance test, no matter how the hue is changed, the streak unevenness generated in the polarizing plate 1 can be made inconspicuous.

Specifically, the change in the orthogonal hue measured before and after the endurance test of the polarizing plate 1 will be described with reference to FIG. 5. In addition, FIG. 5 is an ab chromaticity coordinate diagram for explaining a change in orthogonal hue measured before and after the endurance test of the polarizing plate 1.

The change in the orthogonal hue measured before and after the endurance test of the polarizing plate 1 can be measured using a spectrophotometer or the like.

In addition, in this embodiment, the transmission hue is measured by a spectrophotometer. Then, it was heated to 105 ° C. for 30 minutes in a dry gas environment, and then the transmission hue was measured again by a spectrophotometer. Then, it was confirmed that the initial hue of the polarizing plate 1 and the transmission hue measured after the endurance test did not change in the symbol area surrounded by the a-coordinate axis and the b-coordinate axis.

In addition, the streak-like unevenness generated in the polarizing plate 1 can be observed by transmitting light with orthogonal polarized light on the backlight. Specifically, the polarizing plate may be attached to the illumination surface of a white backlight, and the polarizing plate 1 may be provided thereon so that the absorption axis becomes orthogonal, and observation of uneven intensity may be performed visually.

In the case where a retardation plate such as a λ / 4 plate, a positive C plate, or a λ / 2 plate is included as the protective films 3 and 4 of the polarizing plate 1, if such a retardation plate can be used as the opposite side of the backlight (visual recognition Side) method is set on the backlight and observed. When both the protective films 3 and 4 of the polarizing plate 1 have the structure of a retardation plate, a retardation plate may be provided on a backlight on which the polarizing plate is bonded on the illumination surface, and the polarizing plate 1 may be formed thereon. The orthogonal polarization mode is set for observation.

In the present embodiment, in terms of orthogonal tones measured before and after the endurance test of the polarizing plate 1, the meaning of "the area of the symbol surrounded by the a-axis and the b-axis does not change" has a meaning similar to, for example, "in the first The ab color chromaticity diagram shown in Figure 5 shows that the area between the a-coordinate axis and the b-coordinate axis does not cross the quadrant. " In this case, even if the orthogonal hue of the polarizing plate 1 is changed before and after the endurance test, no matter how the hue is changed, the streaky unevenness generated by the polarizing plate 1 may be inconspicuous. On the other hand, if the area enclosed by the a-coordinate axis and the b-coordinate axis is across quadrants, it is easy to see the streak-like unevenness generated in the polarizing plate 1 due to the change in orthogonal tones.

As far as the streak unevenness generated by the polarizing plate 1 is concerned, the height difference ΔH of the streak unevenness on the surface of the polarizing plate 1 is preferably 80 to 250 nm. The stripe-shaped uneven height difference ΔH is obtained by scanning the surface of the polarizing plate 1 in a direction orthogonal to the extending direction of the stripes when the protective films 3 and 4 have been removed. At the same time, the surface unevenness was measured linearly. From the measurement results, the height (H1) of the apex of the raised portion having the highest average line with respect to the surface and the two adjacent to the highest raised portion can be obtained by the following formula (1). The total of the depth (H2) of the bottom portion of the deeper recessed portion among the recessed portions is used to obtain ΔH. The extension direction of the stripes is usually the same direction as the extension direction (MD). 80nm ≦ △ H = H1 + H2 ≦ 250nm‧‧‧ (1)

The polarizing plate 1 of this embodiment adjusts the orthogonal hue measured in the initial state and after the endurance test so that the area of the symbol surrounded by the a-axis and the b-axis in the ab chromaticity coordinate does not change. Regardless of how the color tone is changed, the streak-like unevenness generated in such a polarizing plate 1 can be made inconspicuous.

In addition, the polarizing plate 1 of this embodiment can adjust the orthogonal hue by adjusting the hue of the polarizer 2 and selecting protective films 4 and 5 arranged on at least one side or both sides of the polarizing plate 1.

In the polarizing plate 1 of this embodiment, the transmittance (Ty) of the photometric correction monomer is preferably 44.0% or more, more preferably 44.3% or more, and still more preferably 44.5% or more. Moreover, in the polarizing plate 1 of this embodiment, the photometric correction polarization (Py) is 95% or more, preferably 98% or more, and more preferably 99% or more. Ty and Py can be measured using, for example, a spectrophotometer.

In addition to the present invention, in addition to the above-mentioned polarizing plate 1, the above-mentioned polarizing plates 1A, 1B, or a polarizing plate containing a retardation film such as a λ / 4 plate, a positive C plate, or a λ / 2 plate can also be borrowed. The orthogonal hue measured in the initial state and after the endurance test is adjusted in such a way that the symbol area surrounded by the a-axis and the b-axis in the ab chromaticity coordinate does not change, regardless of how the hue changes, and can be polarized. The streak-like unevenness caused by the light transmitted through the polarizer 2 in the crossed polarization state generated by the plate becomes inconspicuous.

(Manufacturing method of polarizing plate)

Next, the manufacturing method of the polarizing plate of this embodiment is demonstrated with reference to FIG.

FIG. 6 is a schematic diagram showing a manufacturing apparatus 100 for the polarizing film of the polarizer 2 described above. The arrows shown in FIG. 6 indicate the conveyance direction of the film F serving as a polarizing film.

In this embodiment, first, using the manufacturing apparatus 100 shown in FIG. 6, a polarizing film as a polarizing plate 2 among the above-mentioned polarizing plates 1 is produced. Specifically, a long unstretched PVA-based resin film (raw material film) F is used as a starting material, and this film F is continuously conveyed along the film conveying path of the manufacturing apparatus 100, and after passing through a predetermined processing step , And continuous production of long polarizing film.

The predetermined processing step may include a swelling processing step of immersing the film F in the swelling bath 102, a dyeing processing step of immersing the film F after the swelling processing step in the dyeing bath 103, and Cross-linking treatment step in which film F is immersed in cross-linking bath 104, cleaning treatment step in which film F after cross-linking treatment is immersed in washing bath 105, and extension processing step in which uniaxial stretching treatment is performed on film F being transported A drying treatment step for drying the film F after the washing treatment step in a drying furnace 106. Other processing steps can be added as needed.

The polarizing film manufacturing apparatus 100 shown in FIG. 6 is configured in such a manner that the film F is continuously unrolled from the raw material roll 101, and is transported along the film conveying path, and the film F is sequentially passed therethrough. The swelling bath 102, the dyeing bath 103, the crosslinking bath 104, and the washing bath 105 on the film conveyance path, and finally the film F is passed through the drying furnace 106. The obtained polarizing film can be directly conveyed, for example, to a manufacturing step of the next polarizing plate 1 (a step of laminating a protective film on one or both sides of the polarizing film).

In addition, in the manufacturing apparatus 100 shown in FIG. 6, the swelling bath 102, the dyeing bath 103, the crosslinking bath 104, and the washing bath 105 are each provided with one tank as a process for storing the film F. In the case of a liquid treatment bath, any one or more treatment baths may be provided in a structure of two or more tanks as required.

The manufacturing apparatus 100 shown in FIG. 6 is located on the film conveying path, and in addition to the processing baths 102 to 105 described above, it is also appropriately arranged to support the film F to be conveyed and to change the conveyed film as necessary. Guide rolls 30 to 41 for the transport direction of the film F; press / hold the transported film F, and transmit the driving force caused by its rotation to the film F, and change the transport of the transported film F as necessary Directional nip rolls are comprised from 50 to 55.

The guide rollers 30 to 41 and the rolls 50 to 55 may be arranged before and after the processing baths 102 to 105 or in the processing baths 102 to 105. Thereby, the film F can be introduced / impregnated into the processing baths 102 to 105, and can be extracted from the processing baths 102 to 105. For example, one or more guide rollers 30 to 41 are provided in each of the processing baths 102 to 105, and the film F is conveyed along these guide rollers 30 to 41, whereby the film F can be immersed in each of the processing baths 102 to 1055. .

In the manufacturing apparatus 100 shown in FIG. 6, rolls 50 to 55 are arranged before and after each of the processing baths 102 to 105. With this, in any one or more of the processing baths 102 to 105, a rotational speed difference is provided between the rolls 50 to 55 arranged before and after the processing bath, and the film F can be uniaxially stretched in the longitudinal direction to perform roll-to-roll stretching.

Hereinafter, each processing step performed on the film F when the polarizing film is produced will be described.

    <Swelling process step>    

The swelling treatment step is performed to remove impurities existing on the surface of the film F which is a raw material film, remove plasticizers existing in the film F, impart easy dyeability, and plasticize the film F. The processing conditions are determined to be within a range in which the object can be achieved without causing defects such as extreme dissolution of the film F and loss of transparency.

As the raw material film, an unstretched PVA-based resin film having a thickness of 65 μm or less, preferably about 10 to 50 μm, and more preferably about 10 to 35 μm can be used. The raw material film is usually a roll (reel-shaped article) in which a long unstretched PVA-based resin film is prepared. However, the raw film may be a stretched film that has been uniaxially stretched in a gas before the swelling treatment step.

In the swelling treatment step, when the film (raw material film) F continuously rolled out from the raw material roll 101 is sequentially passed through the roll 50 and the guide rollers 30 to 32, the treatment liquid contained in the swelling bath 102 is immersed for a predetermined time. Thereby, the film F is subjected to a swelling treatment. As for the film F, a uniaxial stretching process may be performed in the swelling bath 102 using the difference in the rotation speed of the rolls 50 and 51 as a stretching process step.

In the treatment liquid of the swelling bath 102, in addition to pure water, boric acid (refer to Japanese Patent Application Laid-Open No. 10-153709) and chloride (refer to Japanese Patent Application Laid-Open No. 06-281816) can be used in the range of about 0.01 to 10% by weight. (Gazette), aqueous solutions of inorganic acids, inorganic salts, water-soluble organic solvents, and alcohols.

When the film F is an unstretched film, the temperature of the swelling bath 102 is, for example, about 10 to 50 ° C, preferably about 10 to 40 ° C, and more preferably about 15 to 30 ° C. The immersion time of the film F is preferably about 10 to 300 seconds, and more preferably about 20 to 200 seconds. On the other hand, when the film F is an stretched film, the temperature of the swelling bath 102 is, for example, about 20 to 70 ° C, and preferably about 30 to 60 ° C. The immersion time of the film F is preferably about 30 to 300 seconds, and more preferably about 60 to 240 seconds.

In the swelling treatment, a problem that the so-called "film F swells in the width direction and wrinkles in the film F" easily occurs. As a means for removing such wrinkles and transporting the film F, the guide rollers 30, 31 and / or the guide roller 32 are used, for example, an expander roll, a spiral roll, a convex roll ( crown roll) rolls with expansion function, or other expansion devices such as cross guider, bend bar, tenter crip. On the other hand, extension treatment may be performed as another means for suppressing the generation of wrinkles.

In the swelling process, since the film F also swells and expands in the conveying direction of the film F, when the film F is not actively extended, in order to eliminate the slack of the film F in the conveying direction, it is preferable to adopt a regulating arrangement in the swelling bath, for example. The speed of the rolls 50 and 51 before and after the 102 and other means. Furthermore, for the purpose of stabilizing the transportation of the film F in the swelling bath 102, the water flow in the swelling bath 102 is controlled by a shower in water, or an EPC device [Edge Position Control (Edge Position Control) device: inspection film is used in combination. The end of the device, etc.] is also useful.

The film F derived from the swelling bath 102 is sequentially conveyed to the dyeing bath 103 side through the guide roller 32 and the roll 51.

<Dyeing process steps>

The dyeing treatment step is performed for the purpose of adsorbing a dichroic dye and orienting the film F after the swelling treatment step. The processing conditions are determined to be within a range in which the object can be achieved without causing defects such as extreme dissolution of the film F and loss of transparency.

In the dyeing treatment step, the film F after the swelling treatment step is immersed in the treatment liquid contained in the dyeing bath 103 for a predetermined time while passing through the roll 51 and the guide rollers 33 to 35 in this order. Thereby, the film F can be dyed. For the film F, a uniaxial stretching process may be performed in the dyeing bath 103 using the difference in the rotational speed of the rolls 51 and 52 as a stretching process step.

The film F provided in the dyeing treatment step is preferably a film F which has been subjected to a uniaxial stretching treatment at least to a certain degree in order to improve the dyeability of the dichroic pigment, and is subjected to a uniaxial stretching treatment before the dyeing treatment, or In addition to the uniaxial stretching process before the dyeing process, it is preferable to perform the uniaxial stretching process during the dyeing process.

When iodine is used as the dichroic dye in the treatment liquid of the dyeing bath 103, for example, an aqueous solution having a concentration of iodine / potassium iodide / water = about 0.003 to 0.3 / about 0.1 to 10/100 in a weight ratio can be used. Instead of potassium iodide, other iodides such as zinc iodide may be used, and potassium iodide may be used in combination with other iodides. In addition, compounds other than iodide may coexist with boric acid, zinc chloride, cobalt chloride, and the like. When boric acid is added, the point of containing iodine is different from the crosslinking treatment described later. If the aqueous solution contains about 0.003 parts by weight or more of iodine with respect to 100 parts by weight of water, it can be regarded as the dyeing bath 103.

In this case, the temperature of the dyeing bath 103 is usually about 10 to 45 ° C, preferably 10 to 40 ° C, and more preferably 20 to 35 ° C. The immersion time of the film F in this case is usually about 30 to 600 seconds, preferably 60 to 300 seconds.

On the other hand, when the treatment liquid of the dyeing bath 103 uses a water-soluble dichroic dye as the dichroic dye, for example, a dichroic dye having a concentration in a weight ratio / water = about 0.001 to 0.1 / 100 (preferably About 0.003 to 0.03 / about 0.1 to 10/100). At this time, a dyeing auxiliary agent or the like may coexist in the treatment solution of the dyeing bath 103, and for example, it may contain an inorganic salt such as sodium sulfate and a surfactant. The dichroic dye may be used alone, or two or more dichroic dyes may be used in combination.

The temperature of the dyeing bath 103 in this case is, for example, about 20 to 80 ° C, preferably 30 to 70 ° C. The immersion time of the film F in this case is usually about 30 to 600 seconds, preferably 60. To about 300 seconds.

The dyeing process is the same as the case of the swelling process described above. As a means for removing the wrinkles of the film F and transporting the film F, the guide rollers 33, 34 and / or the guide roller 35 may be used such as a telescopic roller, a spiral Rolls, convex rollers with sizing functions can also be other sizing devices such as cross guide rollers, curved rods, and tenter clips. On the other hand, the other means for suppressing the generation of wrinkles is the same as in the case of the swelling treatment described above, and an extension treatment can be performed.

The film F derived from the dyeing bath 103 is sequentially introduced to the cross-linking bath 104 through the guide roll 35 and the roll 52.

<Crosslinking process steps>

The cross-linking treatment step is a treatment for the purpose of making it water-resistant or adjusting color tone by cross-linking. In the cross-linking treatment step, when the film F after the dyeing treatment step is sequentially passed through the roll 52 and the guide rollers 36 to 38, the film F is immersed in the treatment liquid contained in the cross-linking bath 104 for a predetermined time. Thereby, the film F is subjected to a crosslinking treatment. For the film F, a uniaxial stretching process may be performed in the cross-linking bath 104 using the difference in the rotational speed of the rolls 52 and 53 as a stretching process step.

As the treatment liquid of the crosslinking bath 104, an aqueous solution containing boric acid, for example, about 1 to 10 parts by weight relative to 100 parts by weight of water can be used. When the dichroic pigment used in the dyeing treatment is iodine, the treatment liquid of the crosslinking bath 104 is preferably one containing iodide in addition to boric acid, and its amount can be set to 1 for 100 parts by weight of water, for example. To 30 parts by weight. Examples of the iodide include potassium iodide, zinc iodide, and the like. Compounds other than iodide may be coexisted with, for example, zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate, and the like.

The crosslinking treatment can be performed by appropriately changing the concentration of the crosslinking agent (boric acid, etc.) and iodide, and the temperature of the crosslinking bath depending on the purpose. For example, when the purpose of the crosslinking treatment is to make it water-resistant by crosslinking, and when the unstretched polyvinyl alcohol-based resin film is sequentially subjected to swelling treatment, dyeing treatment, and crosslinking treatment, the crosslinking bath contains crosslinking. The liquid of the agent may be an aqueous solution having a concentration of boric acid / iodide / water = 3 to 10/1 to 20/100 in a weight ratio. Moreover, if necessary, other cross-linking agents such as glyoxal or glutaraldehyde may be used instead of boric acid, and boric acid may be used in combination with other cross-linking agents.

The temperature of the crosslinking bath 104 is usually about 50 to 70 ° C, preferably 53 to 65 ° C. The immersion time of the film F is usually about 10 to 600 seconds, preferably 20 to 300 seconds, and more preferably 20 to 200 seconds. On the other hand, when the pre-stretched film F is sequentially subjected to a dyeing treatment and a crosslinking treatment, the temperature of the crosslinking bath 104 is usually about 50 to 85 ° C, preferably 55 to 80 ° C.

In the cross-linking treatment for the purpose of adjusting color tone, for example, when using iodine as a dichroic pigment, a cross-linking having a concentration of boric acid / iodide / water = 1 to 5/3 to 30/100 in a weight ratio may be used. bath. The temperature of the crosslinking bath 104 when the film F is immersed is usually about 10 to 45 ° C. The immersion time of the film F is usually about 1 to 300 seconds, preferably 2 to 100 seconds.

The crosslinking treatment may be performed a plurality of times, usually 2 to 5 times. In this case, the composition and temperature of each of the crosslinking baths 104 used may be the same or different as long as they are within the above ranges. In the case of a crosslinking treatment that is water-resistant by crosslinking and a crosslinking treatment for adjusting color tone, a plurality of steps may be performed separately.

In the case where the crosslinking treatment is the same as the swelling treatment described above, as a means for removing the wrinkles of the film F and transporting the film F, a guide roller 36, 37 and / or a guide roller 38 such as a telescopic roller may be used. , Spiral rollers, convex rollers with a widening function, can also be used, such as cross guide rollers, bending rods, tenter clips other expansion devices. On the other hand, the other means for suppressing the generation of wrinkles is the same as in the case of the swelling treatment described above, and an extension treatment can be performed.

The film F derived from the cross-linking bath 104 is introduced into the cleaning bath 105 through the guide roll 38 and the roll 53 in this order.

<Washing process steps>

The washing treatment step is performed for the purpose of removing excess boric acid, iodine, and other agents adhered to the film F. In the washing treatment step, for example, when the film F after the cross-linking treatment step passes the roll 53 and the guide rollers 39 to 41 in this order, the film F is immersed in the washing liquid (water) contained in the washing bath 105 for a predetermined time. Alternatively, the film F after the crosslinking treatment step is sprayed with water as a shower. Alternatively, these washing treatments can be used in combination.

In the manufacturing apparatus 100 shown in FIG. 6, the case where the film F is immersed in the washing bath 105 and a washing process is exemplified. The temperature of the washing bath 105 is usually about 2 to 40 ° C. The immersion time of the film F is usually about 2 to 120 seconds.

The washing process is the same as the above swelling process. As a means for removing the wrinkles of the film F and transporting the film F, it can be used on the guide rollers 39, 40 and / or the guide roller 41, such as a telescopic roller. The helical rollers, convex rollers, and other rollers with expansion function can also be other expansion devices such as cross guide rollers, curved rods, and tenter clips. On the other hand, the other means for suppressing the generation of wrinkles is the same as in the case of the swelling treatment described above, and an extension treatment can be performed.

The film F derived from the washing bath 105 is introduced into the drying furnace 106 side through the guide roll 41 and the roll 54 in this order.

<Drying process steps>

In the drying treatment step, the film F after the washing treatment step is subjected to a drying treatment. The drying process of the film F is not particularly limited, and may be performed using the drying furnace 106 in the manufacturing apparatus 100 shown in FIG. 6. More specifically, the film F may be dried using, for example, a hot-air dryer, a far-infrared heater, or the like.

The drying temperature of the film F is, for example, 20 to 100 ° C, and preferably 20 to 80 ° C. The drying time of the film F is, for example, 10 to 600 seconds, and preferably 30 to 300 seconds.

<Extended processing steps>

The stretching processing step is a wet or dry uniaxial stretching processing of the film F between the series of processing steps described above (that is, before or after any one or more processing steps and / or during any one or more processing steps) .

As for the specific method of uniaxial stretching, for example, a speed difference may be provided between two rolls constituting the film conveying path (for example, two rolls arranged before and after the processing bath), and longitudinal uniaxial stretching may be performed. Stretching between rolls; or hot roll stretching, stent stretching, etc. as described in Japanese Patent No. 2731813, stretching between rolls is preferred.

The stretching treatment may be performed a plurality of times from the film F to the time when the polarizing film is obtained. In addition, the stretching treatment is also advantageous for suppressing the occurrence of wrinkles in the film F.

The final cumulative stretching ratio of the polarizing film is usually about 4.5 to 7 times, preferably 5 to 6.5 times, based on the unstretched film F as a reference.

<Other processing steps>

In the manufacturing step of the polarizing film, processing steps other than the processing steps described above may be added. Examples of the additional processing steps include, for example, after the cross-linking processing step, an immersion treatment step (color-adding treatment step) in an aqueous iodide solution that does not contain boric acid, or a method that includes zinc chloride that does not contain boric acid. An immersion treatment step (zinc treatment step) and the like of an aqueous solution.

The polarizer 2 can be obtained by appropriately cutting the produced polarizing film. The polarizer 2 may have a square shape or an elongated film. As described above, although the manufacturing steps of the polarizing film to be the polarizer 2 have been described, the polarizing film to be the polarizer 2 may be manufactured by other methods.

Next, after the above-mentioned polarizer 2 is manufactured, the above-mentioned polarizer 1 can be manufactured by the following steps: a preliminary processing step of performing a preliminary treatment on the bonding surfaces of the polarizer 2 and / or the protective films 3 and 4; A lamination treatment step of attaching the protective films 3 and 4 on both sides of the polarizer 2 through an adhesive; a hardening treatment step of curing the polarizer 2 attached with the protective films 3 and 4.

<Preliminary processing steps>

The preliminary processing step is to perform a corona treatment and a flame treatment on the bonding surfaces of the polarizer 2 and / or the protective films 3 and 4 in order to improve the adhesion between the polarizer 2 and the protective films 3 and 4 before the bonding processing step. , Plasma treatment, ultraviolet irradiation, primer coating treatment, saponification treatment and other surface treatments.

<Lamination process steps>

In the bonding process, the protective films 3 and 4 are bonded to both surfaces of the polarizer 2 with an adhesive. The adhesive may be an aqueous adhesive or an active energy ray-curable adhesive. The bonding conditions are such that the amount of the adhesive applied on the surface of the polarizer 2 is set to be larger.

<Hardening process steps>

The hardening process is to harden the polarizer 2 to which the protective films 3 and 4 are bonded. When a water-based adhesive is used, after the protective films 3 and 4 are adhered, the adhesive layer is dried to be cured. The drying temperature is, for example, 30 to 100 ° C, preferably 40 to 90 ° C. The drying time is, for example, 30 to 1200 seconds, and preferably 60 to 900 seconds. After drying, aging may be performed at room temperature or a temperature slightly higher than room temperature, for example, at a temperature of about 20 to 45 ° C.

When an active energy ray-curable adhesive is used, after the polarizer 2 and the protective films 3 and 4 are bonded together, they are cured by irradiating active energy rays (ultraviolet rays, electron rays, X-rays, etc.). Although the light irradiation time is controlled by various active energy ray hardening type adhesives and is not particularly limited, it is preferable to set the cumulative light amount expressed as the product of the irradiation intensity and the irradiation time to 10 to 2,500 mJ / cm ² .

The polarizing plate 1 is the same as the polarizing plate 2 and may be a rectangular shape or an elongated film. The square-shaped polarizing plate 1 can be obtained, for example, by cutting an elongated polarizing plate 1. The long polarizing plate 1 may be a roll (reel-shaped object) of the polarizing plate 1.

The manufacturing method of the polarizing plate 1 according to this embodiment includes a tone adjustment step of adjusting the initial region and the end of the endurance test so that there is no change in the area of the symbol raised by the a coordinate axis and the b coordinate axis in the ab chromaticity coordinate. The measured orthogonal tone.

As for the specific tone adjustment procedure, the initial tone in the polarizing plate 1 and the orthogonal tone measured after the endurance test can be adjusted by adjusting the tone of the polarizer 2. The hue of the polarizer 2 can be determined by the concentration of the treatment liquid (for example, the concentration of potassium iodide or dye in the dyeing bath 103, the concentration of boric acid in the crosslinking bath 104, the concentration of potassium iodide, etc.), the temperature of the treatment liquid, and washing with water. The strength (time, temperature), the thickness of the film F, and its stretching ratio are adjusted. Among them, it is also useful to adjust the intensity of washing in terms of the adjustment of orthogonal tones.

In the tone adjustment step, the initial state of the polarizing plate 1 and the orthogonal tone measured after the endurance test can be adjusted by selecting the protective films 3 and 4 arranged on at least one or both sides of the polarizer 2. . That is, the initial state of the polarizing plate 1 and the orthogonal tone measured after the endurance test can also be adjusted by the type of the protective films 3 and 4 selected.

In terms of adjustment of the orthogonal tone change, the protective films 3 and 4 are preferably films made of a cycloolefin resin, a cellulose resin, a polyester resin, and an acrylic resin. The protective film 3 on the outermost surface may be provided with a hard coat layer.

In the tone adjustment step, the orthogonal tone measured in the initial state of the polarizing plate 1 and after the endurance test is adjusted so as to change away from the a coordinate axis and the b coordinate axis in the ab chromaticity coordinate. good. Thus, even if the orthogonal hue of the polarizing plate 1 is changed before and after the endurance test, since the a coordinate axis and the b coordinate axis in the ab chromaticity coordinates do not cross the quadrant, the polarizer can be used regardless of the color tone change. 1 The streaky unevenness produced becomes inconspicuous.

In addition, in the present invention, in addition to the case where the above-mentioned polarizing plate 1 is manufactured, the polarizing plates 1A and 1B and the polarizing plate containing a λ / 4 plate, a positive C plate, a λ / 2 plate, etc., are in an initial state and durable The orthogonal hue measured after the test is also a hue adjustment step by setting "the adjustment is made in a manner that the area of the symbol raised by the a-axis and the b-axis in the ab chromaticity coordinate does not change", regardless of the change in hue , The streak unevenness generated in the manufactured polarizing plate can be made inconspicuous.

    [Example]    

The effect of the present invention will be explained below with reference to examples. The present invention is not limited to the following examples, and can be appropriately modified and implemented within a range not changing the gist of the present invention.

<Example 1>

In Example 1, except that the polarizing film manufacturing apparatus 100 shown in FIG. 6 uses two cross-linking baths 104 (to distinguish, the first cross-linking bath 104a and the second cross-linking bath 104a Except for the joint bath 104b), the rest are manufactured using the same manufacturing apparatus as the manufacturing apparatus 100 described above, and a protective film is bonded to both sides of the obtained polarizing film to produce a polarizing plate.

(1) Swelling treatment steps

First, a 30-μm-thick polyvinyl alcohol film (raw material film) (trade name “Kuraray Poval Film VF-PE # 3000” manufactured by Kuraray Co., Ltd., with an average degree of polymerization of 2400 and a degree of saponification of 99.9 mole%) were continuously rolled from the raw material roll While being rolled out, it was transported and immersed in a swelling bath filled with pure water at 20 ° C for 30 seconds. In this swelling treatment step, roll-to-roll extension (longitudinal uniaxial extension) is performed by applying a rotational speed difference between the rolls 50 and 51. The stretching ratio based on the raw film is 2.5 times.

(2) Dyeing process steps

Next, the film passing through the roller 51 was immersed in a 30 ° C dyeing bath in which pure water / potassium iodide / iodine / boric acid (mass ratio) was 100/2 / 0.01 / 0.3 for 120 seconds. In this dyeing process, a roll speed difference is also provided between the rolls 51 and 52 to perform roll-to-roll extension (longitudinal uniaxial extension). The stretching ratio based on the film after the swelling treatment step was 1.1 times.

(3) Cross-linking processing steps

Next, the film passing through the roll 52 was immersed in a 56 ° C cross-linking bath 104a of pure water / potassium iodide / boric acid (mass ratio) of 100/12/4 for 70 seconds. A rotation speed difference is provided between the roll and the rolls 52 and 53 provided between the first cross-linking bath 104a and the second cross-linking bath 104b to perform roll-to-roll extension (longitudinal uniaxial extension). The stretching ratio based on the film after the dyeing process step was 1.9 times.

(4) Complementary color processing steps

Next, the film after the first crosslinking treatment was immersed in a 40 ° C crosslinking bath 104b having potassium iodide / boric acid / pure water (mass ratio) of 9 / 2.9 / 100 for 10 seconds.

(5) Washing process steps

Next, the membrane after the second crosslinking treatment was immersed in a washing bath 105 in which pure water at 5 ° C was placed for 5 seconds.

(6) Drying steps

Next, the film after the washing process step was passed through a drying furnace and heated and dried at 80 ° C. for 190 seconds to produce a polarizing film. The thickness of the obtained polarizing film was about 12 μm.

(7) Laminating process steps

Next, an aqueous adhesive containing 5 parts by mass of polyvinyl alcohol with respect to 100 parts by mass of water was prepared as an adhesive. On both sides of the polarizing film produced as described above, a protective film shown in Table 1 below was laminated using the prepared water-based adhesive. The obtained laminated body was dried by heating and the adhesive was dried to prepare a polarizing plate. The thickness of the adhesive layer in the obtained polarizing plate was about 50 nm.

<Measurement of Transmittance of Photometric Correction Cell>

Using a spectrophotometer with an integrating sphere ("V7100" manufactured by JASCO Corporation), the photometric correction unit transmittance (Ty) of the obtained polarizing plate was measured in accordance with "JIS Z 8729".

The measurement results are shown in Table 1 below.

<Measurement of Surface Convexity of Polarizer>

The obtained polarizing plate was cut into small pieces of 10 cm × 5 cm, immersed in 600 mL of dichloromethane, and subjected to ultrasonic treatment at room temperature for 30 minutes to dissolve and remove the bonded first protective film and the second protective film. .

In the case of the polarizing film from which these protective films have been removed, the surface of the polarizer with the adhesive attached to the surface of the front side (the side to which the first protective film is attached) is perpendicular to the direction in which it extends. Scanning was performed in the direction, and the unevenness of the surface of the polarizer to which the adhesive was attached was linearly measured. Then, from the measurement results, the size of the undulation (the unevenness of the unevenness) and the unevenness interval were calculated. The calculation results are shown in Table 1 below.

Here, the uneven height difference and the uneven interval are values calculated in the following manner.

Concave and convex height difference: relative to the surface average line, the height of the apex of the highest raised part (H1), the depth of the bottom of the deeper recessed part of the two recessed parts adjacent to the highest raised part respectively (H2).

Concave-convex interval: The distance between the vertex of the highest convex part and the bottom of the deeper one of the two concave parts adjacent to the highest convex part, in parallel with respect to the surface average line.

The surface unevenness was measured under the following conditions.

Measuring device: Vert Scan (registered trademark) (R5500G, manufactured by Ritsubishi Systems Corporation)

Objective lens (magnification): 2.5 times

Measurement range: 3700 × 2800μm

Resolution: 640 × 480 pixels

Measurement mode: wave mode

Surface correction: 4 treatments

<Measurement of hue>

The orthogonal a value and the orthogonal b value of the manufactured polarizing plate were measured using a spectrophotometer with a integrating sphere ("V7100" manufactured by JASCO Corporation). The measurement results are shown in Table 1 below.

After that, the manufactured polarizing plate was supplied to a dry gas environment and heated at 105 ° C. for 30 minutes. Using a spectrophotometer ("V7100" manufactured by JASCO Corporation) with an integrating sphere, the orthogonal a value and orthogonal b value of the polarizer after heating were measured. The measurement results are shown in Table 1 below.

<Measurement of stripe unevenness>

On the illuminating surface of the white backlight module with a brightness of 20000cd / m ² , a polarizing plate A with a photometric correction monomer transmittance (Ty) of 41.6% and a photometric correction polarization (Py) of 99.997 is attached, and Place a polarizer on it.

In this case, the first protective film shown in the following Table 1 of the polarizing plate is used as the upper surface, and the transmission axis of the polarizing plate A and the transmission axis of the polarizing plate are perpendicularly intersected (orthogonal polarization state). Place. In this state, the stripe-shaped unevenness was confirmed visually from the first protective film side of the polarizing plate. Stripe unevenness is evaluated in the following four stages. The results of this evaluation are shown in Table 1 below.

0: Stripe unevenness is not recognized.

1: Stripe unevenness is hardly recognized.

2: Stripe unevenness is slightly visually recognized.

3: Stripe unevenness is clearly recognized.

Thereafter, the manufactured polarizing plate was heated at 105 ° C. for 30 minutes in a dry gas environment. The heated polarizing plate was checked for streak-like unevenness in the same manner as described above, and evaluated in the same manner as described above. The evaluation results are shown in Table 1 below. In the first embodiment, the color tone change before and after the endurance test is shown in an ab chromaticity coordinate diagram in FIG. 7.

<Example 2>

In Example 2, it was produced in the same manner as in Example 1 except that only the conditions for cleaning the polarizing film were changed in order to adjust the color tone of the polarizing film (specifically, the immersion time was set to 3 seconds). Polarizing plate 2. Then, by the same method as in Example 1 above, the photometric correction unit transmittance (Ty) of the obtained polarizing plate, the surface unevenness of the polarizer, the hue change before and after the endurance test, and the stripe shape before and after the endurance test were measured. Uneven variation. The measurement results are shown in Table 1 below. Further, in Example 2, those in which the hue change before and after the endurance test is shown in an ab chromaticity coordinate diagram are shown in FIG. 7.

<Example 3>

(1) Swelling treatment steps

First, a 30-μm-thick polyvinyl alcohol film (raw material film) (trade name “Kuraray Poval Film VF-PE # 3000” manufactured by Kuraray Co., Ltd., with an average degree of polymerization of 2400 and a degree of saponification of 99.9 mole%) were continuously rolled from the raw material roll While being unrolled, it was transported and immersed in a swelling bath containing 20 ° C pure water for 30 seconds. In this swelling treatment step, a roll speed difference is provided between the rolls 50 and 51 to perform roll-to-roll extension (longitudinal uniaxial extension). The stretching ratio based on the raw film is 2.2 times.

(2) Dyeing process steps

Next, the film passing through the roll 51 was immersed in a 30 ° C dyeing bath having a pure water / potassium iodide / iodine / boric acid (mass ratio) of 100 / 1.4 / 0.01 / 0.3 for 120 seconds. In this dyeing process, a rotation speed difference is also provided between the rolls 51 and 52 to perform roll-to-roll extension (longitudinal uniaxial extension). The stretch ratio based on the film after the swelling treatment step was 1.2 times.

(3) Cross-linking processing steps

Next, the film passing through the roll 52 was immersed in a 53 ° C crosslinking bath 104a having a pure water / potassium iodide / boric acid (mass ratio) of 100/9/4 for 70 seconds. A rotation speed difference is provided between the rolls and the rolls 52 and 53 provided between the first cross-linking bath 104a and the second cross-linking bath 104b (longitudinal uniaxial extension). The stretching ratio based on the film after the dyeing process step was 2.1 times.

(4) Complementary color processing steps

Next, the membrane after the first cross-linking treatment was immersed in a 50 ° C cross-linking bath 104b with pure water / potassium iodide / boric acid (mass ratio) of 100/9 / 3.9 for 10 seconds.

(5) Washing process steps

Next, the membrane after the second crosslinking treatment was immersed in a washing bath 105 to which pure water at 13 ° C was added for 5 seconds.

(6) Drying steps

Next, the film after the washing process step was passed through a drying furnace and heated and dried at 80 ° C. for 190 seconds to produce a polarizing film. The thickness of the obtained polarizing film was about 12 μm.

(7) Laminating process steps

Next, on both sides of the produced polarizing film, a water-based adhesive containing 5 parts by mass of polyvinyl alcohol with respect to 100 parts by mass of water was used, and a protective film shown in Table 1 below was laminated. The obtained laminated body was dried by heating and the adhesive was dried to prepare a polarizing plate. The thickness of the adhesive layer in the obtained polarizing plate was about 50 nm.

Then, by the same method as in Example 1 above, the photometric correction unit transmittance (Ty) of the obtained polarizing plate, the surface unevenness of the polarizer, the hue change before and after the endurance test, and the stripe shape before and after the endurance test were measured. Uneven variation. The measurement results are shown in Table 1 below. Regarding Example 3, the change in hue before and after the endurance test is shown in an ab chromaticity coordinate diagram, and is shown in FIG. 8.

<Example 4>

In Example 4, a polarizing plate was produced in the same manner as in Example 3 except that the type of the protective film was changed to the protective film shown in Table 1 below. Then, by the same method as in Example 1, the photometric correction unit transmittance (Ty) of the obtained polarizing plate 4, the surface unevenness of the polarizer, the hue change before and after the endurance test, and the fringes before and after the endurance test were measured. Uneven variation in shape. The measurement results are shown in Table 1 below. Note that in Example 4, those whose color tone changes before and after the endurance test are shown in an ab chromaticity coordinate graph are shown in FIG. 8.

<Comparative example 1>

In Comparative Example 1, except that only the cleaning conditions for the polarizing film were changed in order to adjust the color tone of the polarizing film (specifically, the immersion time was set to 3 seconds), the rest were produced in the same manner as in Example 3. Polarizer. Then, by the same method as in Example 1 above, the photometric correction unit transmittance (Ty) of the obtained polarizing plate, the surface unevenness of the polarizer, the hue change before and after the endurance test, and the stripe shape before and after the endurance test were measured. Uneven variation. The measurement results are shown in Table 1 below. In Comparative Example 1, those in which hue changes before and after the endurance test are shown in an ab chromaticity coordinate graph are shown in FIG. 8.

<Comparative example 2>

In Comparative Example 2, a polarizing film was produced in the same manner as in Example 4 except that only the cleaning conditions for the polarizing film were changed in order to adjust the color tone of the polarizing film (specifically, the immersion time was set to 3 seconds). board. Then, by the same method as in Example 1 above, the photometric correction unit transmittance (Ty) of the obtained polarizing plate, the surface unevenness of the polarizer, the hue change before and after the endurance test, and the stripe shape before and after the endurance test were measured. Uneven variation. The measurement results are shown in Table 1 below. In Comparative Example 2, those in which the hue change before and after the endurance test is shown in an ab chromaticity coordinate graph are shown in FIG. 8.

<Reference Example 1>

As Reference Example 1, a polarized light was produced in the same manner as in Example 1 except that pure water / potassium iodide / iodine / boric acid (mass ratio) was set to 100/2 / 0.03 / 0.3 in the dyeing process step. board. Then, by the same method as in Example 1, the photometric correction unit transmittance (Ty) of the obtained polarizing plate, the unevenness of the surface of the polarizer, the hue change before and after the endurance test, and the stripe shape before and after the endurance test were measured. The non-uniform change was measured by the same method as in Example 1 described above. The measurement results are shown in Table 1 below. Regarding Reference Example 1, those in which the hue change before and after the endurance test is shown in an ab chromaticity coordinate diagram are shown in FIG. 9.

The protective films in Table 1 are as follows.

Protective film A: diagonally extending cyclic polyolefin resin film with UV-curable hard coat layer, thickness 29 μm

Protective film B: triethylfluorene-based cellulose film, thickness 25 μm

Protective film C: Triethyl cellulose film with UV-curable hard coating, thickness 32μm

Protective film D: Triethyl cellulose film with UV-curable hard coating (but the ultraviolet absorption ability is different from that of protective film C). Thickness 32μm

Furthermore, in Table 1, the axis of the orthogonal hue before and after the endurance test is the hue of the symbol region where the symbol area indicated by the ab chromaticity coordinate axis has not changed is "○". On the other hand, the axis of the orthogonal hue before and after the endurance test is the hue of the hue of the symbol area where the ab chromaticity coordinate axis is changed, as "x".

As shown in Table 1 and FIGS. 7 to 9, the orthogonal hue before and after the endurance test in Examples 1 to 4 is that the symbol area indicated by the ab chromaticity coordinate axis has not changed, and the stripe unevenness is small, even After the endurance test, the stripe unevenness did not increase significantly and was good.

On the other hand, in Comparative Examples 1 and 2, the area of the symbol indicated by the orthogonal tone system ab chromaticity coordinate axis before and after the endurance test changed, and after the endurance test, the stripe unevenness also increased significantly. In Reference Example 1, the polarizing film having a photometric correction monomer transmittance (Ty) of less than 44% did not recognize streaks.

Claims (10)

    A polarizing plate comprising a polarizer and a protective film disposed on at least one side of the polarizer via an adhesive layer, wherein a photometric correction monomer transmittance (Ty) measured in an initial state is 44% or more The orthogonal hue measured in the initial state and after the endurance test has no change in the area of the symbol in the ab chromaticity coordinate, which is surrounded by the a coordinate axis and the b coordinate axis.         The polarizing plate as described in item 1 of the scope of patent application, wherein after the endurance test is "started from at least the initial state, supplied to a dry gas environment, and heated at 105 ° C for 30 minutes".         The polarizing plate according to item 1 or 2 of the scope of patent application, wherein the polarizer is a polarizing film in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film.         The polarizing plate according to any one of claims 1 to 3 in the scope of patent application, wherein the thickness of the polarizer is 3 to 15 μm.         The polarizing plate as described in any one of claims 1 to 4, wherein when the protective film is removed, the surface of the polarizer to which the adhesive is attached has unevenness with a height difference of 80 to 250 nm.         The polarizing plate according to any one of claims 1 to 5, wherein the aforementioned polarizer is an iodine-based polarizer.         A display device includes a display panel and the polarizing plate according to any one of claims 1 to 6 of the scope of patent application.         A manufacturing method of a polarizing plate is a manufacturing method of a polarizing plate including a polarizing plate and a protective film disposed on at least one side of the polarizing plate via an adhesive layer, including a hue adjusting step based on ab chromaticity coordinates. The orthogonal shades measured in the initial state and after the endurance test are adjusted in such a way that the symbol areas surrounded by the a-coordinate axis and the b-coordinate axis do not change.         The method for manufacturing a polarizing plate according to item 8 of the scope of patent application, wherein the hue adjustment step adjusts at least the hue of the polarizer.         According to the manufacturing method of the polarizing plate according to item 8 or 9 of the scope of patent application, the aforementioned hue adjusting step is to select the protective film disposed on at least one side or both sides of the polarizing plate.