JP2019117381A - Polarizing film and production method of the same, optical film and image display device - Google Patents

Abstract

To provide a production method of a polarizing film by which the polarizing film can be prevented from curling while adhesion performance of an adhesive layer between a polarizer and a transparent protective film is increased.SOLUTION: The present invention provides a production method of a polarizing film having a first transparent protective film disposed on one surface of a polarizer and a second transparent protective film disposed on the other surface via an adhesive layer. The method includes an adhesion step of adhering the polarizer to the first transparent protective film and adhering the polarizer to the second transparent protective film via the adhesive layer that is obtained by first irradiating the first transparent protective film side with active energy rays and then irradiating the second transparent protective film side with active energy rays to cure an active energy ray-curable adhesive composition. The first transparent protective film has a transmittance of less than 5% for rays at a wavelength of 365 nm; and the second transparent protective film has a transmittance of 80% or more for rays at a wavelength of 365 nm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a polarizing film and a method of manufacturing the same. The said polarizing film can form image display apparatuses, such as a liquid crystal display (LCD), an organic electroluminescence display, CRT, and PDP, as this or the optical film which laminated | stacked this.

  Liquid crystal display devices are rapidly developing in the market for watches, mobile phones, PDAs, laptop computers, monitors for personal computers, DVD players, TVs and the like. The liquid crystal display device visualizes the polarization state by switching of the liquid crystal, and a polarizer is used from the display principle. In particular, in applications such as TVs, increasingly higher brightness, higher contrast, and wider viewing angle are required, and even for polarizing films, increasingly higher transmittance, higher degree of polarization, higher color reproducibility, and the like are required.

As a polarizer, for example, iodine-based polarizers having a structure in which iodine is adsorbed to polyvinyl alcohol (hereinafter, also simply referred to as “PVA”) and stretched and having a high transmittance and a high polarization degree are most generally widely used. It is used. In general, a polarizing film is used in which a transparent protective film is attached to both sides of a polarizer with a so-called water-based adhesive in which a polyvinyl alcohol-based material is dissolved in water (Patent Document 1 and Patent Document 2 below) ). As the transparent protective film, triacetyl cellulose having high moisture permeability is used.

  In the case of using a water-based adhesive such as a polyvinyl alcohol-based adhesive (so-called wet lamination) when producing a polarizing film, a drying step is required after laminating a polarizer and a transparent protective film. . In order to improve the productivity of the polarizing film, it is desirable to shorten the drying step or to adopt another bonding method which does not require the drying step.

  In the case of using a water-based adhesive, the moisture content of the polarizer must be relatively high (usually, the moisture content of the polarizer is about 30%) in order to enhance the adhesion to the polarizer. It is not possible to obtain a polarizing film with good adhesion. However, the polarizing film thus obtained has problems such as large dimensional change and poor optical characteristics under high temperature and high temperature and high humidity. On the other hand, in order to suppress the dimensional change, the moisture content of the polarizer can be lowered, or a transparent protective film with low moisture permeability can be used. However, when such a polarizer and a transparent protective film are bonded using a water-based adhesive, the drying efficiency is lowered, the polarization characteristic is lowered, or the appearance defect occurs, and a substantially useful polarizing film is obtained. I can not

  Also, as represented by TV in particular, with the recent increase in the size of image display devices, the increase in size of polarizing films is also very important in terms of productivity and cost (yield, increase in number of items taken). There is. However, in the case of the polarizing film using the above-mentioned water-based adhesive, the heat of the backlight causes the dimensional change of the polarizing film, which becomes uneven and so-called light leakage (unevenness of black display in part of the entire screen) There is a problem that) becomes noticeable.

  In order to solve the problems in the above-described wet lamination, an active energy ray-curable adhesive that does not contain water or an organic solvent has been proposed. For example, in Patent Document 3 below, a radically polymerizable compound having a molecular weight of 1,000 or less containing (A) a polar group, and a radically polymerizable compound having a molecular weight of 1,000 or less not containing a polar group (B) (D) An active energy ray-curable adhesive containing a photopolymerization initiator is disclosed. However, since the combination of radically polymerizable compounds (monomers) constituting such an adhesive is designed especially for the purpose of improving the adhesion to a norbornene resin film, it tends to be inferior in adhesion to a polarizing film. The

  Patent Document 4 below discloses an active energy ray-curable adhesive containing a photopolymerization initiator having a molar absorption coefficient of 400 or more at a wavelength of 360 to 450 nm and an ultraviolet ray-curable compound as essential components. However, since the combination of monomers constituting such an adhesive is designed mainly for the purpose of preventing warpage and deformation at the time of bonding an optical disk or the like, when used as a polarizing film, Tend to be inferior in adhesion.

  In Patent Document 5 below, (A) a (meth) acrylic compound having two or more (meth) acryloyl groups in a molecule in a total amount of 100 parts by weight of (meth) acrylic compound, and (B) a hydroxyl group in a molecule And an active energy ray-curable adhesive comprising a (meth) acrylic compound having only one polymerizable double bond and (C) a phenol ethylene oxide modified acrylate or a nonyl phenol ethylene oxide modified acrylate ing. However, the combination of the monomers constituting such an adhesive is relatively low in compatibility between the respective monomers, and there is concern that the phase separation proceeds along with it, and the transparency of the adhesive layer is reduced. Further, such an adhesive is intended to improve adhesion by softening the cured product (adhesive layer) (lowering the Tg), and there is concern that the durability such as crack resistance may be deteriorated. Crack resistance can be evaluated by a thermal shock test (heat shock test).

  The inventors of the present invention have developed a radical polymerization type active energy ray-curable adhesive that uses an N-substituted amide-based monomer as a curable component (Patent Document 6 and Patent Document 7 below). Such an adhesive exhibits excellent durability under severe conditions of high humidity and high temperature, but in the market, an adhesive capable of improving further adhesion and / or water resistance is required. It was the fact that there was.

  In Patent Document 8 below, a protective film (A) having ultraviolet impermeability on one side of a polarizer and a protective film (B) having ultraviolet permeability on the other side are bonded via an ultraviolet curing adhesive, respectively. Then, the manufacturing method of the polarizing plate which irradiates an ultraviolet-ray from the outer side of a protective film (B), and simultaneously cures the ultraviolet curing adhesive distribute | arranged to the front and back of a polarizer is described. This manufacturing method is characterized in that the ultraviolet curing adhesive disposed on the front and back of the polarizer is simultaneously cured by ultraviolet irradiation from one side (one-stage irradiation of ultraviolet) to enhance cost merit.

JP, 2006-220732, A JP 2001-296427 A JP, 2008-009329, A Japanese Patent Application Laid-Open No. 09-31416 JP, 2008-174667, A JP, 2008-287207, A JP, 2010-78700, A Patent No. 5090695

  However, the manufacturing method described in Patent Document 8 has the following problems. That is, the reaction rate of the ultraviolet curing adhesive interposed between the protective film (A) having ultraviolet impermeability and the polarizer is not sufficient only by the ultraviolet irradiation from one side, and in some cases, the protective film (A) And the polarizer may peel off. Here, when the UV irradiation intensity is increased to increase the reaction rate of the UV curable adhesive interposed between the protective film (A) and the polarizer, the amount of UV light reaching the polarizer increases, and the polarization characteristics In some cases, the polarizing film curls due to the shrinkage of the polarizer. Furthermore, when the UV irradiation intensity is increased to increase the reaction rate of the UV curable adhesive interposed between the protective film (A) and the polarizer, the amount of UV light reaching the protective film (A) increases. The protective film (A) generates heat as the ultraviolet light is absorbed, and the polarizing film may curl.

  As described above, it is difficult to prevent the curling of the polarizing film while increasing the reaction rate of the adhesive composition interposed between the polarizer and the transparent protective film by the conventional method for producing a polarizing film. It was a fact. In addition, in the case of the conventional active energy ray-curable adhesive composition, the adhesion of the polarizer having a low moisture content may be insufficient, and further improvement of the adhesion is required. The

  This invention is made in view of the said situation, The objective is manufacture of the polarizing film which can prevent the curl of a polarizing film, improving the adhesive performance of the adhesive bond layer between a polarizer and a transparent protective film. To provide a way. Another object of the present invention is to provide a polarizing film, an optical film, and an image display device provided with an adhesive layer having improved adhesion between a polarizer and a transparent protective film and having improved durability and water resistance.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have transparent protection on both sides of the polarizer through the adhesive layer obtained by irradiating the active energy ray-curable adhesive composition with the active energy ray. In the manufacturing method of the polarizing film provided with a film, it discovered that the said subject could be solved by devising the irradiation method of an active energy ray.

Furthermore, the present inventors paid attention to the SP value (solubility parameter) of the curable component in the active energy ray-curable adhesive composition in order to solve the above-mentioned problems. In general, substances having similar SP values can be said to have high affinity to one another. Therefore, for example, when the SP values of the radically polymerizable compounds are close to each other, their compatibility increases, and the SP values of the radically polymerizable compound in the active energy ray curable adhesive composition and the polarizer are close to each other. The adhesion between the adhesive layer and the polarizer is enhanced. Similarly, when the SP value of the radically polymerizable compound in the active energy ray-curable adhesive composition and the protective film (for example, triacetyl cellulose film (TAC), acrylic film, cycloolefin film) are close, the adhesive layer and Adhesion to the protective film is enhanced. As a result of intensive studies by the present inventors based on these tendencies,
(I) designing each SP value of at least three radically polymerizable compounds in the active energy ray-curable adhesive composition within a specific range, and making the composition ratio optimal, and (II) (Meta (Meta) The inventors have found that the above problems can be solved by containing an acrylic oligomer (D) formed by polymerizing an acrylic monomer.

  The present invention was made as a result of the above-mentioned examination, and achieves the above-mentioned object by the following composition.

  That is, the present invention relates to a method for producing a polarizing film in which the first transparent protective film is provided on one side of the polarizer and the second transparent protective film on the other side via the adhesive layer, A coating step of coating an active energy ray-curable adhesive composition on at least one surface of the first transparent protective film or the second transparent protective film, the polarizer, the first transparent protective film, and In the bonding step of bonding the polarizer and the second transparent protective film, first, the active energy ray is irradiated from the first transparent protective film side, and then the active energy ray is irradiated from the second transparent protective film side And the polarizer and the first transparent protective film via the adhesive layer obtained by curing the active energy ray-curable adhesive composition. Method for producing a polarizing film characterized in that the Rabbi comprising said polarizer and bonding process for bonding the second transparent protective film, a.

In the method for producing a polarizing film according to the present invention, first, active energy rays are irradiated from the first transparent protective film side, and then active energy rays are irradiated from the second transparent protective film side (two-step irradiation). As a result, compared with the conventional one-step irradiation, the reaction rate of the adhesive layer can be increased while the curling of the transparent protective film is prevented, and the adhesion between the polarizer and the transparent protective film can be improved.

  In the present invention, as the first transparent protective film and the second transparent protective film, a UV transmitting transparent protective film having a light transmittance of 80 nm or more at a wavelength of 365 nm, and / or a light transmittance of 5 nm at a wavelength of 365 nm It is possible to select various combinations of the UV opaque transparent protective film.

That is, in the method for producing the polarizing film,
(1) The first transparent protective film has a light transmittance at a wavelength of 365 nm of 80% or more, and the second transparent protective film has a light transmittance at a wavelength of 365 nm of less than 5%.
(2) The first transparent protective film has a light transmittance at a wavelength of 365 nm of less than 5%, and the second transparent protective film has a light transmittance at a wavelength of 365 nm of 80% or more.
(3) The first transparent protective film and the second transparent protective film have a light transmittance of less than 5% at a wavelength of 365 nm, and (4) the first transparent protective film and the second transparent protective film Preferably, the light transmittance at a wavelength of 365 nm is 80% or more. The polarized light which raised the reaction rate of an adhesive bond layer and improved the adhesiveness of a polarizer and a transparent protective film, preventing curl of a transparent protective film even if it is any combination of said (1)-(4) Films can be produced.

  Moreover, in the manufacturing method of the said polarizing film, it is preferable that the said active energy ray is what contains the visible ray of a wavelength range 380-450 nm.

  Moreover, in the manufacturing method of the said polarizing film, it is preferable that the ratio of the integral illuminance of a wavelength range 380-440 nm and the integral illuminance of a wavelength range 250-370 nm is 100: 0-100: 50 for the said active energy ray.

  Furthermore, in the method for producing a polarizing film, it is preferable that the active energy ray is a gallium lamp as a light source and a block filter is used to block ultraviolet rays of 380 nm or less.

（式中、Ｒ^１およびＲ^２は−Ｈ、−ＣＨ_２ＣＨ_３、−ＩＰｒまたはＣｌを示し、Ｒ^１およびＲ^２は同一または異なっても良い）を含有することが好ましい。 A compound represented by the following general formula (1) as an active energy ray-curable adhesive composition as a photopolymerization initiator;

(Wherein, R ¹ and R ^{2 each} represent —H, —CH ₂ CH ₃ , —IPr or Cl, and R ¹ and R ² may be the same or different).

（式中、Ｒ^３、Ｒ^４およびＲ^５は−Ｈ、−ＣＨ_３、−ＣＨ_２ＣＨ_３、−ＩＰｒまたはＣｌを示し、Ｒ^３、Ｒ^４およびＲ^５は同一または異なっても良い）を含有することが好ましい。 Further, in the method for producing a polarizing film, a compound further represented by the following general formula (2) as a photopolymerization initiator;

(Wherein, R ³ , R ⁴ and R ^{5 each} represent —H, —CH ₃ , —CH ₂ CH ₃ , —IPr or Cl, and R ³ , R ⁴ and R ⁵ may be the same or different) It is preferable to contain.

  UV radiation with a wavelength of 360 to 370 nm is the highest, such as UV radiation using metal halide lamp or high pressure mercury lamp as a light source, UV radiation is applied through a transparent protective film having UV transparency, and UV curable adhesive When the composition is cured, curling may occur in the transparent protective film because the transparent protective film absorbs ultraviolet light and generates heat.

  On the other hand, in the method for producing a polarizing film according to the present invention, when visible light in the wavelength range of 380 to 450 nm is used, the ratio of integrated illuminance in the wavelength range of 380 to 440 nm and integrated illuminance in the wavelength range of 250 to 370 nm is 100. When using the active energy ray which is from 0 to 100: 50, it becomes possible to remarkably suppress the active energy ray absorption in the transparent protective film, unlike the case of using the ordinary ultraviolet ray. As a result, it is possible to prevent the occurrence of curling of the polarizing film due to heat generation in the transparent protective film accompanying absorption of active energy rays.

  The photopolymerization initiator of the general formula (1) can initiate polymerization by long-wavelength light passing through the transparent protective film having UV absorbing ability, and therefore, the adhesive composition can be applied even through the ultraviolet opaque transparent protective film. Can be cured. The active energy ray-curable adhesive composition containing the photopolymerization initiator of the general formula (1) is particularly a transparent protective film having a polarizer and a light transmittance of less than 5% at a wavelength of 365 nm It can be suitably used when forming an adhesive layer which adheres to a film). When the active energy ray-curable adhesive composition contains the photopolymerization initiator of the general formula (1) described above, the active energy ray (visible light) is irradiated over the ultraviolet ray impermeable type transparent protective film, The adhesive layer can be cured. Therefore, an adhesive bond layer can be hardened also in a polarizing film which laminated an ultraviolet ray impermeable type transparent protective film on both sides of a light polarizer. However, as a matter of course, the adhesive layer can be cured even in the case of a polarizing film in which an ultraviolet ray transmitting transparent protective film is laminated.

  In addition, by using the photopolymerization initiators of the general formula (1) and the general formula (2) in combination, the photosensitization reaction of these makes the reaction highly efficient, and the adhesiveness of the adhesive layer is particularly improved.

  Moreover, in the manufacturing method of the said polarizing film, it is preferable that the thickness of the said polarizer is 10 micrometers or less. Furthermore, it is preferable that the total thickness of the said polarizing film is 150 micrometers or less. In the polarizing film, the degree of occurrence of curling after the formation of the adhesive layer is influenced by the thickness of the polarizer and further the total thickness of the polarizing film, and the thinner the film thickness, the easier the curling occurs in the polarizing film . That is, in a polarizing film using a thin polarizer, and further in a thin polarizing film, there are unique problems caused by the thinness. However, according to the method for producing a polarizing film according to the present invention, even when producing a polarizing film using a thin polarizer, and even when producing a thin polarizing film, an adhesive between the polarizer and the transparent protective film It is possible to produce a polarizing film in which the occurrence of curling is prevented while enhancing the adhesion performance of the layer.

Further, in the method for producing a polarizing film, the active energy ray-curable adhesive composition comprises (meth) acrylic monomers and radically polymerizable compounds (A), (B) and (C) as a curable component. Containing an acrylic oligomer (D) formed by polymerization,
The radical polymerizable compound (A) has an SP value of 29.0 (MJ / m ³ ) ^1/2 or more and 32.0 or less (MJ / m ³ ) ^1/2 ,
The radical polymerizable compound (B) has an SP value of 18.0 (MJ / m ³ ) ^1/2 or more and 21.0 (MJ / m ³ ) ^{1/2 or} less.
The radical polymerizable compound (C) has an SP value of 21.0 (MJ / m ³ ) ^1/2 or more and 23.0 (MJ / m ³ ) ^1/2 or less.
When the total amount of the composition is 100% by weight, it is preferable that the composition contains 25 to 80% by weight of the radically polymerizable compound (B).

The SP value of the radically polymerizable compound (B) is 18.0 (MJ / m ³ ) ^1/2 or more and 21.0 (MJ / m ³ ) ^{1/2 or} less, and the composition ratio thereof is 25 to 80% by weight. Is preferred. The radically polymerizable compound (B) has a low SP value, and the water (SP value 47.9) is largely separated from the SP value, which greatly contributes to the improvement of the water resistance of the adhesive layer. The SP value of the radically polymerizable compound (B) is, for example, the SP value (for example, SP value 18.6) of a cyclic polyolefin resin (for example, trade name "Zeonor" manufactured by Nippon Zeon Co., Ltd.) as a transparent protective film. Because they are close, they also contribute to the improvement of adhesion with such a transparent protective film. In order to further improve the water resistance of the adhesive layer, it is preferable to set the SP value of the radically polymerizable compound (B) to less than 20.0 (MJ / m ³ ) ^1/2 . In particular, in consideration of the water resistance of the adhesive layer, when the total amount of the composition is 100% by weight, the radically polymerizable compound (B) is preferably 30% by weight or more, and more preferably 40% by weight or more. . On the other hand, when the amount of the radically polymerizable compound (B) is too large, the content of the radically polymerizable compounds (A) and (C) inevitably decreases, and the adhesion to the adherend tends to decrease. . In addition, since the radically polymerizable compound (B) is separated from the radically polymerizable compound (A) by a large SP value, if the composition ratio is too large, the balance of compatibility between the radically polymerizable compounds collapses, With the progress of phase separation, there is a concern that the transparency of the adhesive layer may be deteriorated. Therefore, when considering the adhesiveness to the adherend and the transparency of the adhesive layer, the composition ratio of the radically polymerizable compound (B) is 75% by weight or less, when the total amount of the composition is 100% by weight. Preferably, it is 70 wt% or less.

The SP value of the radically polymerizable compound (A) in the active energy ray-curable adhesive composition used in the present invention is 29.0 (MJ / m ³ ) ^1/2 or more and 32.0 or less (MJ / m ³ ) It is preferable that it is ^1/2 . Such radically polymerizable compound (A) has a high SP value, for example, a PVA-based polarizer (for example, SP value 32.8) and saponified triacetyl cellulose (TAC; for example, SP value 32.7) as a transparent protective film, It greatly contributes to the improvement of adhesion with the adhesive layer. In particular, in view of the adhesion between the polarizer and / or TAC and the adhesive layer, the total amount of the composition is 100% by weight, preferably 3% by weight or more of the radically polymerizable compound (A), and 5% by weight It is more preferable to make it% or more. On the other hand, the radically polymerizable compound (A) has poor compatibility with the acrylic oligomer (D) formed by polymerizing a (meth) acrylic monomer, and progress of phase separation makes the adhesive layer after curing uneven. It may be Therefore, in order to ensure the uniformity and transparency of the adhesive layer, when the total amount of the composition is 100% by weight, it is preferable to make the radically polymerizable compound (A) 40% by weight or less, 30% by weight It is more preferable to set it as the following.

The SP value of the radically polymerizable compound (C) is preferably 21.0 (MJ / m ³ ) ^1/2 or more and less than 23.0 (MJ / m ³ ) ^1/2 . As described above, the radically polymerizable compound (A) and the radically polymerizable compound (B) are far apart from each other in SP value, and these are poorly compatible with each other. However, since the SP value of the radically polymerizable compound (C) is between the SP value of the radically polymerizable compound (A) and the SP value of the radically polymerizable compound (B), the radically polymerizable compound (A) is By combining the radically polymerizable compound (C) in addition to the radically polymerizable compound (B), the compatibility of the composition as a whole improves in a well-balanced manner. Furthermore, the SP value of the radically polymerizable compound (C) is close to, for example, the SP value (for example, 23.3) of unsaponifiable triacetyl cellulose as a transparent protective film and the SP value (for example, 22.2) for an acrylic film. Also contributes to the improvement of adhesion with these transparent protective films. Therefore, in order to improve water resistance and adhesion in a well-balanced manner, the composition ratio of the radically polymerizable compound (C) is preferably 5 to 55% by weight. As for the composition ratio of a radically polymerizable compound (C), when the compatibility as the whole composition and adhesiveness with a transparent protective film are considered, 10 weight% or more is more preferable. Moreover, when water resistance is considered, it is more preferable that the composition ratio of a radically polymerizable compound (C) is 30 weight% or less.

  The active energy ray-curable adhesive composition used in the present invention is obtained by polymerizing (meth) acrylic monomers in addition to the radically polymerizable compounds (A), (B) and (C) as a curable component. It is preferable to contain an acrylic oligomer (D). By containing the component (D) in the active energy ray-curable adhesive composition, the cure shrinkage upon irradiating and curing the active energy ray in the composition is reduced, and the adhesive, the polarizer, and the transparent protection The interface stress with an adherend such as a film can be reduced. As a result, it is possible to suppress the decrease in the adhesion between the adhesive layer and the adherend. In order to sufficiently suppress the cure shrinkage of the cured product layer (adhesive layer), the adhesive composition preferably contains 3% by weight or more of the acrylic oligomer (D), and contains 5% by weight or more Is more preferred. On the other hand, when the content of the acrylic oligomer (D) in the adhesive composition is too large, the reaction rate when the composition is irradiated with the active energy ray decreases sharply, which may result in curing failure. Therefore, the content of the acrylic oligomer (D) in the adhesive composition is preferably 20% by weight or less, and more preferably 15% by weight or less.

  In the manufacturing method of the said polarizing film, it is preferable to contain the radically polymerizable compound which has an active methylene group, and the radical polymerization initiator (E) which has a hydrogen extraction effect | action. According to such a configuration, the adhesiveness of the adhesive layer of the polarizing film is remarkably improved, even in a high humidity environment or immediately after being taken out of water (in a non-dried state). Although this reason is not clear, the following causes can be considered. That is, the radically polymerizable compound having an active methylene group is incorporated into the main chain and / or side chain of the base polymer in the adhesive layer while polymerizing with other radically polymerizable compounds constituting the adhesive layer, and adhesion Form an agent layer. In the polymerization process, when a radical polymerization initiator (E) having a hydrogen abstraction function is present, hydrogen is extracted from the radically polymerizable compound having an active methylene group while the base polymer constituting the adhesive layer is formed. Radicals are generated in the methylene group. And the methylene group which radical generate | occur | produced and the hydroxyl group of polarizers, such as PVA, react, and a covalent bond is formed between an adhesive bond layer and a polarizer. As a result, it is presumed that the adhesion of the adhesive layer of the polarizing film is significantly improved even in the non-dried state. As a radical polymerization initiator (E) which has a hydrogen-extraction action, the compound represented, for example by the said General formula (1) can be illustrated.

  In the method for producing a polarizing film, the active methylene group is preferably an acetoacetyl group.

  In the method for producing a polarizing film, it is preferable that the radically polymerizable compound having an active methylene group is acetoacetoxyalkyl (meth) acrylate.

  In the method for producing a polarizing film, the radical polymerization initiator (E) is preferably a thioxanthone radical polymerization initiator.

  In the method for producing a polarizing film, when the total amount of the composition is 100% by weight, 1 to 50% by weight of the radical polymerizable compound having an active methylene group and 0.1 to 10 of a radical polymerization initiator (E) It is preferable to contain it by weight.

  In the method for producing a polarizing film, when the homopolymers of radically polymerizable compounds (A), (B) and (C) each have a glass transition temperature (Tg) of 60 ° C. or higher, the durability of the adhesive layer is Is particularly preferable because it can prevent the occurrence of heat shock cracks. Here, the term "heat shock crack" means, for example, a phenomenon in which the polarizer tears in the stretching direction when it contracts, and in order to prevent this, it is necessary to use a heat shock temperature range (-40.degree. C. to 60.degree. C.) It is important to suppress the expansion and contraction of the child. As described above, when the glass transition temperature (Tg) of each homopolymer of the radically polymerizable compounds (A), (B) and (C) is 60 ° C. or higher, when the adhesive layer is formed, the Tg is also Get higher. As a result, the rapid change in elastic modulus of the adhesive layer in the heat shock temperature range can be suppressed, and the expansion / contraction force acting on the polarizer can be reduced, so that the generation of heat shock cracks can be prevented. .

  Here, the method of calculating the SP value (solubility parameter) in the present invention will be described below.

(Calculation method of solubility parameter (SP value))
In the present invention, the solubility parameter (SP value) of a radically polymerizable compound, a polarizer, various transparent protective films, etc. is calculated using the FEDORS method ["Polymer Engineering & Science (POLYMER ENG. &SCI.)", No. 14, No. 2 (1974), pp. 148-154] That is,

（ただしΔｅｉは原子または基に帰属する２５℃における蒸発エネルギー、Δｖｉは２５℃におけるモル体積である）にて計算して求めることができる。

(Where Δei is evaporation energy at 25 ° C. belonging to an atom or a group, and Δvi is molar volume at 25 ° C.).

  The Δei and Δvi in the above equation indicate constant numerical values given to I atoms and groups in the main molecule. In addition, representative examples of the values of Δe and Δv given to atoms or groups are shown in Table 1 below.

In the method for producing a polarizing film, when the total amount of the radically polymerizable compound in the active energy ray-curable adhesive composition is 100 parts by weight, the radically polymerizable compound (A),
It is preferable to contain 70 to 100 parts by weight in total of (B) and (C) and an acrylic oligomer (D) formed by polymerizing a (meth) acrylic monomer. According to this configuration, the ratio of the radically polymerizable compounds (A), (B) and (C) in the adhesive composition to the acrylic oligomer (D) can be sufficiently ensured, and therefore, the adhesive property of the adhesive layer Can be improved, and the durability and water resistance can be further improved. In order to improve adhesion, durability and water resistance in a well-balanced manner, the radically polymerizable compounds (A), (B) and (C) and the acrylic oligomer (D) are contained in a total amount of 80 to 100 parts by weight. It is preferable to contain 90 to 100 parts by weight.

  In the method of producing a polarizing film, the radically polymerizable compound (A) is preferably hydroxyethyl acrylamide and / or N-methylol acrylamide. Moreover, in the manufacturing method of the said polarizing film, it is preferable that the said radically polymerizable compound (B) is a tripropylene glycol diacrylate. Furthermore, in the method of producing a polarizing film, the radically polymerizable compound (C) is preferably acryloyl morpholine and / or N-methoxymethyl acrylamide. According to these configurations, the adhesiveness, durability and water resistance of the adhesive layer can be improved in a more balanced manner.

  The polarizing film according to the present invention is a polarizing film in which transparent protective films are provided on both sides of a polarizer via an adhesive layer, and is produced by the method for producing a polarizing film according to any one of the above It is characterized by Such a polarizing film is prevented from curling and has high adhesion of the adhesive layer.

In the polarizing film, it is preferable moisture permeability of the transparent protective film is not more than 150g ^/ m 2 ^/ 24h. According to this configuration, it is difficult for moisture in the air to enter the polarizing film, and it is possible to suppress the change in the moisture content of the polarizing film itself. As a result, it is possible to suppress the curl and dimensional change of the polarizing film caused by the storage environment.

  In the manufacturing method of the said polarizing film, it is preferable that the moisture content of the said polarizer at the time of the said bonding process is less than 15%. According to this manufacturing method, the drying load of the polarizing film obtained after the bonding step (lamination) is reduced, and the adhesion between the polarizer and the transparent protective film is excellent, and the durability and the water resistance of the adhesive layer are obtained. Polarizing films can be produced with excellent adhesive layers.

  The optical film according to the present invention is characterized in that at least one of the polarizing plates described above is laminated.

  Furthermore, the image display device according to the present invention is characterized in that the polarizing film as described above and / or the optical film as described above are used. In the optical film and the image display device, the polarizer of the polarizing film and the transparent protective film are firmly bonded via the adhesive layer, and the durability and the water resistance of the adhesive layer are excellent.

A conceptual view showing an example of a method of manufacturing a polarizing film according to the present invention Conceptual diagram showing an example of a polarizing film according to the present invention The conceptual diagram which shows an example of the manufacturing method of the polarizing film which concerns on this invention provided with the thin-shaped polarizer as a polarizer

  The conceptual diagram which shows an example of the manufacturing method of the polarizing film which concerns on FIG. 1 at this invention is shown. However, the method for producing a polarizing film according to the present invention is not limited to the example shown in FIG. In the method for producing a polarizing film according to the present embodiment, an active energy ray-curable adhesive composition is applied to at least one surface of the polarizer 1, the first transparent protective film 2, or the second transparent protective film 3. A coating step, a bonding step of bonding the polarizer 1 and the first transparent protective film 2; a bonding step of bonding the polarizer 1 and the second transparent protective film 3; first, the first transparent protective film 2 The active energy ray is irradiated from the side, and then the active energy ray is irradiated from the second transparent protective film 3 side to cure the active energy ray-curable adhesive composition, via the adhesive layer obtained, It includes an adhesion step of adhering the polarizer 1 and the first transparent protective film 2 and the polarizer 1 and the second transparent protective film 3. In the laminating step, the polarizer 1 and the first transparent protective film 2, and the polarizer 1 and the second transparent protective film 3 may be laminated simultaneously, or may be laminated sequentially, continuously or intermittently. .

(Coating process)
In the coating step, the active energy ray-curable adhesive composition is applied to at least one surface of the polarizer 1, the first transparent protective film 2, or the second transparent protective film 3. Specifically, an active energy ray-curable adhesive composition may be coated on one side or both sides of the polarizer 1, and the polarizer 1 of the first transparent protective film 2 and / or the second transparent protective film 3 The active energy ray-curable adhesive composition may be coated on the side to be bonded to the surface. In the example shown in FIG. 1, an active energy ray-curable adhesive is used on the surface of the first transparent protective film 2 and the second transparent protective film 3 on the side to be bonded to the polarizer 1 using the adhesive coating machine 4 ′. Coating agent composition.

  The surface modification process may be performed on the polarizer 1 and the transparent protective films 2 and 3 before applying the active energy ray-curable adhesive composition. Specific treatments include corona treatment, plasma treatment, treatment by saponification treatment, and the like.

  The coating method of the active energy ray-curable adhesive composition is appropriately selected depending on the viscosity of the composition and the intended thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater and the like. In addition, methods such as dipping can be used appropriately for coating.

(Bonding process)
The polarizer 1 and the transparent protective films 2 and 3 are pasted together via the adhesive coated as mentioned above. The lamination of the polarizer 1 and the transparent protective films 2 and 3 can be performed by a roll laminator or the like.

  When the moisture content of the said polarizer at the time of the said bonding process is less than 15%, since the drying load of the polarizing film obtained after the bonding process (lamination) can be reduced, it is preferable. Examples of such a low moisture content polarizer include thin type polarizers that can be easily reduced in moisture content during heating and drying. The thin polarizer will be described later.

  As described later, a thin polarizer (thin high-performance polarizing film) can be suitably produced by forming a thin high-performance polarizing film on one side of a resin substrate. When implementing the manufacturing method which concerns on this invention using this thin-shaped polarizer, you may implement a coating process and a bonding process twice each. Specifically, for example, when a thin polarizer is used in the manufacturing method according to the present invention, an active energy ray-curable type is formed on the thin polarizer side surface of a laminate film in which the thin polarizer is laminated on one side of a resin substrate. A first coating step of applying an adhesive composition, a first bonding step of bonding a first transparent protective film from the coated surface side of the thin polarizer, and peeling the resin substrate from the thin polarizer Peeling step, a second coating step of applying an active energy ray-curable adhesive composition on the side of the thin polarizer from which the resin substrate has been peeled, and a coated surface of the thin polarizer You may have the 2nd bonding process which bonds a 2nd transparent protective film together from the side. In the first coating step, instead of applying the active energy ray-curable adhesive composition to the thin polarizer, active energy is applied to the bonding surface of the first transparent protective film with the thin polarizer. A radiation curable adhesive composition may be applied. Further, also in the second coating step, instead of applying the active energy ray-curable adhesive composition to the thin polarizer, active energy is applied to the bonding surface of the second transparent protective film with the thin polarizer. A radiation curable adhesive composition may be applied.

  The conceptual diagram which shows an example of the polarizing film which concerns on FIG. 2 at this invention is shown. As shown in FIG. 2, in the polarizing film 10 according to the present embodiment, the first transparent protective film 2 is formed on one side of the polarizer 1 through the layer of the active energy ray-curable adhesive composition in the bonding step. The second transparent protective film 3 is provided on the other side, and the adhesive layer 4 is formed by curing the layer.

(Adhesive process)
The bonding process will be described based on FIG. First, active energy rays are irradiated from the first transparent protective film 2 side, and then active energy rays are irradiated from the second transparent protective film 3 side to cure the active energy ray-curable adhesive composition. The polarizer 1 and the first transparent protective film 2 and the polarizer 1 and the second transparent protective film 3 are adhered via the adhesive layer thus formed. In the example shown in FIG. 1, an active energy ray is irradiated from the first transparent protective film 2 side using an active energy ray irradiator 5A as a light source, and then using the active energy ray irradiator 5B as a light source The active energy ray is irradiated from the side of the second transparent protective film 3 to cure the active energy ray-curable adhesive composition.

  In the present invention, as the first transparent protective film and the second transparent protective film, a UV transmitting transparent protective film having a light transmittance of 80 nm or more at a wavelength of 365 nm, and / or a light transmittance of 5 nm at a wavelength of 365 nm It is possible to select various patterns of the UV opaque transparent protective film.

(Pattern 1; transparent → opaque pattern)
First, active energy rays are irradiated (first irradiation) from the side of the first transparent protective film (ultraviolet light transmissive transparent protective film) having a light transmittance of 80% or more at a wavelength of 365 nm, and then the light transmittance of a wavelength of 365 nm is The active energy ray is irradiated from the side of the second protective film (ultraviolet light impermeable type transparent protective film) side which is less than 5% (second irradiation) to bond the polarizer and the transparent protective film. In the present invention, although the curing reaction proceeds even in the active energy ray-curable adhesive composition interposed between the second transparent protective film and the polarizer by the first irradiation, the reaction rate is not sufficiently high. . That is, if it is only the first irradiation, the adhesion between the second transparent protective film and the polarizer is insufficient, and peeling may occur between them. However, by further performing the second irradiation, the curing reaction proceeds sufficiently even with the active energy ray-curable adhesive composition interposed between the second transparent protective film and the polarizer, and the adhesiveness of the adhesive layer is increased. With the increase, curling of the polarizing film can be prevented.

  Similarly, in the present invention, the following pattern can be adopted as the bonding step. With any pattern, the curing reaction sufficiently proceeds even with the active energy ray-curable adhesive composition interposed between the second transparent protective film and the polarizer, and the adhesiveness of the adhesive layer is enhanced. It is possible to prevent curling of the polarizing film.

(Pattern 2; opaque → transparent pattern)
First, active energy rays are irradiated (first irradiation) from the side of the first transparent protective film (ultraviolet light impermeable protective film) having a light transmittance of less than 5% at a wavelength of 365 nm, and then the light transmittance of a wavelength of 365 nm is The active energy ray is irradiated (second irradiation) from the side of the second protective film (ultraviolet light transmissive transparent protective film) side which is 80% or more (second irradiation) to bond the polarizer and the transparent protective film.

(Pattern 3; opaque → opaque pattern)
First, active energy rays are irradiated (first irradiation) from the side of the first transparent protective film (ultraviolet light impermeable protective film) having a light transmittance of less than 5% at a wavelength of 365 nm, and then the light transmittance of a wavelength of 365 nm is The active energy ray is irradiated from the side of the second protective film (ultraviolet light impermeable type transparent protective film) side which is less than 5% (second irradiation) to bond the polarizer and the transparent protective film.

(Pattern 4; transmission → transmission pattern)
First, active energy rays are irradiated (first irradiation) from the side of the first transparent protective film (ultraviolet light transmitting protective film) having a light transmittance of 80% or more at a wavelength of 365 nm, and then the light transmittance of 80 nm is 80%. Active light rays are irradiated (second irradiation) from the side of the second protective film (ultraviolet light transmissive transparent protective film) which is% or more to adhere the polarizer and the transparent protective film.

  As the active energy ray, one containing an electron beam and visible light in the wavelength range of 380 nm to 450 nm can be used. In addition, although the long wavelength limit of visible light is about 780 nm, while visible light exceeding 450 nm does not contribute to the absorption of the polymerization initiator, it may cause heat generation of the transparent protective film and the polarizer. For this reason, in the present invention, it is preferable to use a band pass filter to block visible light on the long wavelength side exceeding 450 nm.

  The irradiation conditions of the electron beam may be any suitable conditions as long as the active energy ray-curable adhesive composition can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive and curing may be insufficient. If the acceleration voltage exceeds 300 kV, the penetration through the sample is too strong and damage to the transparent protective film or the polarizer There is a risk of giving The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. If the irradiation dose is less than 5 kGy, the adhesive will be undercured, and if it exceeds 100 kGy, the transparent protective film and the polarizer will be damaged, causing a decrease in mechanical strength and yellowing to obtain predetermined optical characteristics. I can not

  Electron beam irradiation is usually performed in an inert gas, but if necessary, it may be performed in the air or under a condition where a small amount of oxygen is introduced. Depending on the material of the transparent protective film, by appropriately introducing oxygen, it is possible to cause oxygen inhibition to occur on the transparent protective film surface that the electron beam first strikes, to prevent damage to the transparent protective film, and only to the adhesive Electron beams can be irradiated efficiently.

  However, in the method for producing a polarizing film according to the present invention, the wavelength range of active energy rays is used to prevent curling of the polarizing film while enhancing the adhesive performance of the adhesive layer between the polarizer and the transparent protective film. It is preferable to use an active energy ray that contains visible light of 380 nm to 450 nm, and in particular, the irradiation amount of visible light in the wavelength range of 380 nm to 450 nm is the largest. When using the transparent protective film (ultraviolet non-transparent transparent protective film) to which the ultraviolet absorptivity is imparted, in order to absorb the light having a wavelength shorter than about 380 nm, the light having a wavelength shorter than 380 nm has an active energy ray curable adhesive composition It does not contribute to the polymerization reaction because it does not reach the substance. Furthermore, light of a wavelength shorter than 380 nm absorbed by the transparent protective film is converted into heat, and the transparent protective film itself generates heat, which causes defects such as curls and wrinkles of the polarizing film. Therefore, in the present invention, it is preferable to use an apparatus that does not emit light having a wavelength shorter than 380 nm as the active energy ray generation apparatus, and more specifically, the integrated illuminance in the wavelength range 380 to 440 nm and the wavelength range 250 to 370 nm It is preferable that a ratio of the integrated illuminance to the integrated illuminance is 100: 0 to 100: 50, and more preferably 100: 0 to 100: 40. As an active energy ray which satisfy | fills the relationship of such integrated illumination intensity, a gallium enclosure metal halide lamp and the LED light source which light-emits the wavelength range 380-440 nm are preferable. Alternatively, using a low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, super high pressure mercury lamp, incandescent lamp, xenon lamp, halogen lamp, carbon arc lamp, metal halide lamp, fluorescent lamp, tungsten lamp, gallium lamp, excimer laser or sunlight as a light source A band pass filter can be used to block light of wavelengths shorter than 380 nm. In order to prevent the curling of the polarizing film while enhancing the adhesion performance of the adhesive layer between the polarizer and the transparent protective film, it is obtained using a band pass filter capable of blocking light having a wavelength shorter than 400 nm. It is preferable to use the active energy ray, or the active energy ray of wavelength 405 nm obtained using an LED light source.

  In the visible light curing type, it is preferable to heat the active energy ray curable adhesive composition before irradiation with visible light (heating before irradiation), in which case heating to 40 ° C. or higher is preferable, and 50 It is more preferable to heat at a temperature of at least ° C. It is also preferable to heat the active energy ray-curable adhesive composition after irradiation with visible light (heating after irradiation), in which case heating to 40 ° C. or higher is preferable, and heating to 50 ° C. or higher Is more preferred.

  An active energy ray-curable adhesive composition containing the photopolymerization initiator of the general formula (1) is an adhesive layer for bonding, in particular, a polarizer and a transparent protective film having a light transmittance of less than 5% at a wavelength of 365 nm. Can be suitably used when forming When the active energy ray-curable adhesive composition contains the photopolymerization initiator of the general formula (1) described above, ultraviolet rays are irradiated over the transparent protective film having UV absorbing ability to cure the adhesive layer. It can be formed. Therefore, an adhesive bond layer can be hardened also in a polarizing film which laminated a transparent protective film which has UV absorption power on both sides of a light polarizer. However, as a matter of course, the adhesive layer can be cured also in a polarizing film in which a transparent protective film having no UV absorbing ability is laminated.

  As a method for imparting the UV absorbing ability to the transparent protective film, a method of containing an ultraviolet light absorber in the transparent protective film, and a method of laminating a surface treatment layer containing an ultraviolet light absorber on the surface of the transparent protective film may be mentioned.

  Specific examples of the UV absorber include, for example, conventionally known oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like. .

  When the polarizing film according to the present invention is produced in a continuous line, the line speed depends on the curing time of the adhesive, preferably 1 to 500 m / min, more preferably 5 to 300 m / min, still more preferably 10 to 100 m / min. It is min. If the line speed is too small, productivity is poor or damage to the transparent protective film is too large, and a polarizing film that can withstand durability tests and the like can not be produced. If the line speed is too high, curing of the adhesive may be insufficient and the desired adhesion may not be obtained.

  In the polarizing film of the present invention, the polarizer and the transparent protective film are bonded via the adhesive layer formed of the cured product layer of the active energy ray-curable adhesive composition, but the transparent protective film An easily adhesive layer can be provided between the adhesive layer and the adhesive layer. The easily bonding layer can be formed of, for example, various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone resin, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton and the like. These polymer resins can be used alone or in combination of two or more. Other additives may be added to the formation of the easy adhesion layer. Specifically, stabilizers such as tackifiers, ultraviolet absorbers, antioxidants, heat stabilizers and the like may be used.

  The easy adhesion layer is usually provided in advance on a transparent protective film, and the easy adhesion layer side of the transparent protective film is bonded to the polarizer by an adhesive layer. Formation of an easily bonding layer is performed by coating and drying the formation material of an easily bonding layer on a transparent protective film by a well-known technique. The material for forming the easy adhesion layer is usually prepared as a solution diluted to an appropriate concentration in consideration of the thickness after drying, the smoothness of coating, and the like. The thickness of the easily adhesive layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and still more preferably 0.05 to 1 μm. In addition, although the easily bonding layer can be provided with two or more layers, also in this case, it is preferable to make it the total thickness of a easily bonding layer become the said range.

（式中、Ｒ^１およびＲ^２は−Ｈ、−ＣＨ_２ＣＨ_３、−ＩＰｒまたはＣｌを示し、Ｒ^１およびＲ^２は同一または異なっても良い）を単独で使用するか、あるいは一般式（１）で表される化合物と後述する３８０ｎｍ以上の光に対して高感度な光重合開始剤とを併用することが好ましい。一般式（１）で表される化合物を使用した場合、３８０ｎｍ以上の光に対して高感度な光重合開始剤を単独で使用した場合に比べて接着性に優れる。一般式（１）で表される化合物の中でも、Ｒ^１およびＲ^２が−ＣＨ_２ＣＨ_３であるジエチルチオキサントンが特に好ましい。組成物中の一般式（１）で表される化合物の組成比率は、組成物全量を１００重量％としたとき、０．１〜５．０重量％であることが好ましく、０．５〜４．０重量％であることがより好ましく、０．９〜３．０重量％であることがさらに好ましい。 In the active energy ray-curable adhesive composition used in the present invention, a compound represented by the following general formula (1) as a photopolymerization initiator;

(Wherein, R ¹ and R ^{2 each} represent —H, —CH ₂ CH ₃ , —IPr or Cl, and R ¹ and R ² may be the same or different) or used alone or a general formula It is preferable to use together the compound represented by 1) and a highly sensitive photopolymerization initiator for light of 380 nm or more described later. When the compound represented by General formula (1) is used, it is excellent in adhesiveness compared with the case where a highly sensitive photoinitiator with respect to the light 380 nm or more is used alone. Among the compounds represented by the general formula (1), diethylthioxanthone in which R ¹ and R ² are —CH ₂ CH ₃ is particularly preferable. The composition ratio of the compound represented by the general formula (1) in the composition is preferably 0.1 to 5.0% by weight, when the total amount of the composition is 100% by weight, and 0.5 to 4 It is more preferable that it is .0 weight%, and it is further more preferable that it is 0.9 to 3.0 weight%.

  Moreover, it is preferable to add a polymerization start auxiliary as needed. As a polymerization initiation aid, triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, etc. And ethyl 4-dimethylaminobenzoate is particularly preferred. When using a polymerization start auxiliary, the addition amount thereof is usually 0 to 5% by weight, preferably 0 to 4% by weight, most preferably 0 to 3% by weight based on 100% by weight of the total amount of the composition. .

  Moreover, a well-known photoinitiator can be used together as needed. Since the transparent protective film having UV absorbing ability does not transmit light of 380 nm or less, it is preferable to use a photopolymerization initiator highly sensitive to light of 380 nm or more as the photopolymerization initiator. Specifically, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 , 2- (Dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine Oxides, bis (2,4,6-trimethyl benzoyl) -phenyl phosphine oxide, bis (Η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole) 1-yl) -phenyl) titanium and the like.

（式中、Ｒ^３、Ｒ^４およびＲ^５は−Ｈ、−ＣＨ_３、−ＣＨ_２ＣＨ_３、−ＩＰｒまたはＣｌを示し、Ｒ^３、Ｒ^４およびＲ^５は同一または異なっても良い）を使用することが好ましい。一般式（２）で表される化合物としては、市販品でもある２−メチル−１−（４−メチルチオフェニル）−２−モルフォリノプロパン−１−オン（商品名：ＩＲＧＡＣＵＲＥ９０７ メーカー：ＢＡＳＦ）が好適に使用可能である。その他、２−ベンジル−２−ジメチルアミノ−１−（４−モルフォリノフェニル）−ブタノン−１（商品名：ＩＲＧＡＣＵＲＥ３６９ メーカー：ＢＡＳＦ）、２−（ジメチルアミノ）−２−［（４−メチルフェニル）メチル］−１−［４−（４−モルホリニル）フェニル］−１−ブタノン（商品名：ＩＲＧＡＣＵＲＥ３７９ メーカー：ＢＡＳＦ）が感度が高いため好ましい。 In particular, a compound represented by the following general formula (2) in addition to the photopolymerization initiator of the general formula (1) as a photopolymerization initiator;

(Wherein, R ³ , R ⁴ and R ^{5 each} represent —H, —CH ₃ , —CH ₂ CH ₃ , —IPr or Cl, and R ³ , R ⁴ and R ⁵ may be the same or different) It is preferred to use. As the compound represented by the general formula (2), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (trade name: IRGACURE 907 manufacturer: BASF) which is also a commercial product is preferable It can be used for In addition, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (trade name: IRGACURE 369 manufacturer: BASF), 2- (dimethylamino) -2-[(4-methylphenyl) Methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone (trade name: IRGACURE 379 manufacturer: BASF) is preferred because of its high sensitivity.

The active energy ray-curable adhesive composition used in the present invention has an SP value of 29.0 (MJ / m ³ ) ^1/2 or more and 32.0 or less (MJ / m ³ ) ^1/2 as a curable component. A radically polymerizable compound (A), a radically polymerizable compound (B) having an SP value of 18.0 (MJ / m ³ ) ^1/2 or more and less than 21.0 (MJ / m ³ ) ^1/2 , and It is formed by polymerizing a (meth) acrylic monomer and a radically polymerizable compound (C) having an SP value of 21.0 (MJ / m ³ ) ^1/2 or more and 23.0 (MJ / m ³ ) ^1/2 or less. It contains 25 to 80% by weight of the radically polymerizable compound (B) when it contains an acrylic oligomer (D) and the total amount of the composition is 100% by weight. In the present invention, “the total amount of the composition” means the total amount including various initiators and additives in addition to the radically polymerizable compound.

The radically polymerizable compound (A) has a radically polymerizable group such as a (meth) acrylate group, and has an SP value of 29.0 (MJ / m ³ ) ^1/2 or more and 32.0 or less (MJ / m ^{3) Any} compound that is ^1/2 ) can be used without limitation. As a specific example of a radically polymerizable compound (A), hydroxyethyl acrylamide (SP value 29.6), N- methylol acrylamide (SP value 31.5) etc. are mentioned, for example. In the present invention, the (meth) acrylate group means an acrylate group and / or a methacrylate group.

The radically polymerizable compound (B) has a radically polymerizable group such as a (meth) acrylate group, and has an SP value of 18.0 (MJ / m ³ ) ^1/2 or more 21.0 (MJ / m ³ ) ^Any compound that is less than ^1/2 can be used without limitation. As specific examples of the radically polymerizable compound (B), for example, tripropylene glycol diacrylate (SP value 19.0), 1,9-nonanediol diacrylate (SP value 19.2), tricyclodecane dimethanol di- Acrylate (SP value 20.3), cyclic trimethylolpropane formal acrylate (SP value 19.1), dioxane glycol diacrylate (SP value 19.4), EO modified diglycerin tetraacrylate (SP value 20.9), etc. Can be mentioned. In addition, as a radically polymerizable compound (B), a commercial item can also be used suitably, for example, Alonics M-220 (Toagosei Co., Ltd. make, SP value 19.0), light acrylate 1, 9ND-A (Kyoeisha Chemical company) Product, SP value 19.2), light acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 20.9), light acrylate DCP-A (manufactured by Kyoeisha Chemical Co., SP value 20.3), SR-531 (SARTOMER) Company-made, SP value 19.1), CD-536 (made by SARTOMER, SP value 19.4), etc. are mentioned.

The radically polymerizable compound (C) has a radically polymerizable group such as a (meth) acrylate group, and has an SP value of 21.0 (MJ / m ³ ) ^1/2 or more 23.0 (MJ / m ³ ) ^Any compound that is ^1/2 or less can be used without limitation. Specific examples of the radically polymerizable compound (C) include, for example, acryloyl morpholine (SP value 22.9), N-methoxymethyl acrylamide (SP value 22.9), N-ethoxymethyl acrylamide (SP value 22.3) Etc. In addition, as a radically polymerizable compound (C), a commercial item can also be used suitably, for example, ACMO (made by Kojin Co., SP value 22.9), Wasmar 2MA (made by Konno Kosan, SP value 22.9) And Wasmar EMA (manufactured by Kanno Kosan Co., Ltd., SP value 22.3), and Wasmar 3MA (manufactured by Kanno Kosan Co., Ltd., SP value 22.4).

  When the glass transition temperature (Tg) of each homopolymer of the radically polymerizable compounds (A), (B) and (C) is 60 ° C. or higher, the Tg of the adhesive layer also becomes high, and the durability is particularly excellent. It will be As a result, for example, when it is set as the adhesive bond layer of a polarizer and a transparent protective film, generation | occurrence | production of the heat shock crack of a polarizer can be prevented. Here, the Tg of the homopolymer of the radically polymerizable compound means the Tg when the radically polymerizable compound is cured (polymerized) alone. The measuring method of Tg is mentioned later.

  The active energy ray-curable adhesive composition preferably has a low viscosity in consideration of the workability and uniformity at the time of coating, and therefore, an acrylic oligomer (D) formed by polymerizing a (meth) acrylic monomer It is preferable that the viscosity is also low. As an acrylic oligomer having a low viscosity and capable of preventing the curing shrinkage of the adhesive layer, one having a weight average molecular weight (MW) of 15000 or less is preferable, one having a weight average of 10000 or less is more preferable, and one having a weight of 5000 or less is particularly preferable. preferable. On the other hand, in order to sufficiently suppress the cure shrinkage of the cured product layer (adhesive layer), it is preferable that the weight average molecular weight (MW) of the acrylic oligomer (D) is 500 or more, and 1000 or more More preferably, it is particularly preferably 1,500 or more. Specific examples of the (meth) acrylic monomer constituting the acrylic oligomer (D) include methyl (meth) acrylate, ethyl (meth) acrylate, N-propyl (meth) acrylate, isopropyl (meth) acrylate, 2 -Methyl-2-nitropropyl (meth) acrylate, N-butyl (meth) acrylate, isobutyl (meth) acrylate, S-butyl (meth) acrylate, T-butyl (meth) acrylate, N-pentyl (meth) acrylate, T-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2,2-dimethylbutyl (meth) acrylate, N-hexyl (meth) acrylate, cetyl (meth) acrylate, N-octyl (meth) acrylate, 2 -Ethylhexyl (meth) acrylic And (meth) acrylic acid (1 to 20 carbon atoms) alkyl esters such as 4-methyl-2-propylpentyl (meth) acrylate and N-octadecyl (meth) acrylate; further, for example, cycloalkyl (meth) Acrylate (eg, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate etc.), aralkyl (meth) acrylate (eg benzyl (meth) acrylate etc.), polycyclic (meth) acrylate (eg, 2-isobornyl (meth)) Acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornylmethyl (meth) acrylate, etc.), hydroxyl group-containing (meth) Acrylic esters (eg, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropylmethyl-butyl (meth) methacrylate etc., alkoxy group or phenoxy group-containing (meth) acrylic acid esters Meta) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate etc., epoxy Group-containing (meth) acrylic acid esters (eg, glycidyl (meth) acrylate etc.), halogen-containing (meth) acrylic acid esters (eg, 2,2,2-trifluoroethyl (meth) acrylate, 2,2 , 2-Trifluoroethylethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate etc., alkylaminoalkyl Examples include (meth) acrylates (eg, dimethylaminoethyl (meth) acrylate etc.) and the like. These (meth) acrylates can be used alone or in combination of two or more. Specific examples of the acrylic oligomer (D) include “ARUFON” manufactured by Toagosei Co., Ltd., “Actflow” manufactured by Soken Chemical Co., Ltd., “JONCRYL” manufactured by BASF Japan, and the like.

The above-mentioned active energy ray-curable adhesive composition preferably further contains a radically polymerizable compound having an active methylene group and a radical polymerization initiator (E) having a hydrogen abstraction effect.

  The radically polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth) acrylic group in the terminal or in the molecule and having an active methylene group. As an active methylene group, an acetoacetyl group, an alkoxy malonyl group, or a cyanoacetyl group etc. are mentioned, for example. Specific examples of the radically polymerizable compound having an active methylene group include, for example, 2-acetoacetoxyethyl (meth) acrylate, 2-acetoacetoxypropyl (meth) acrylate, 2-acetoacetoxy-1-methylethyl (meth) acrylate, etc. Acetoacetoxyalkyl (meth) acrylates; 2-ethoxymalonyloxyethyl (meth) acrylates, 2-cyanoacetoxyethyl (meth) acrylates, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetoxybutyl) Acrylamide, N- (4-acetoacetoxymethylbenzyl) acrylamide, N- (2-acetoacetylaminoethyl) acrylamide and the like can be mentioned. In addition, SP value of the radically polymerizable compound which has an active methylene group is not specifically limited, The compound of arbitrary values can be used.

In the present invention, examples of the radical polymerization initiator (E) having a hydrogen abstraction function include thioxanthone radical polymerization initiators and benzophenone radical polymerization initiators. As a thioxanthone type radical polymerization initiator, the compound represented, for example by the said General formula (1) is mentioned. As a specific example of a compound represented by General formula (1), a thioxanthone, a dimethyl thioxanthone, a diethyl thioxanthone, an isopropyl thioxanthone, a chloro thioxanthone etc. are mentioned, for example. Among the compounds represented by the general formula (1), diethylthioxanthone in which R ¹ and R ² are —CH ₂ CH ₃ is particularly preferable.

  As described above, in the present invention, radicals are generated in the methylene group of the radically polymerizable compound having an active methylene group in the presence of the radical polymerization initiator (E) having a hydrogen abstraction function, and such methylene group and PVA, etc. The hydroxyl groups of the polarizer react with each other to form a covalent bond. Therefore, when the total amount of the composition is 100% by weight to generate radicals in the methylene group of the radically polymerizable compound having an active methylene group and sufficiently form such covalent bond, the radical polymerization having the active methylene group It is preferable to contain 1 to 50% by weight of a compound and 0.1 to 5.0% by weight of a radical polymerization initiator (E), 3 to 30% by weight of a radically polymerizable compound having an active methylene group, and a radical It is more preferable to contain 0.5 to 4.0% by weight of the polymerization initiator (E). Furthermore, it is particularly preferable to contain the radical polymerization initiator (E) in an amount of 0.9 to 3.0% by weight. If the content of the radically polymerizable compound having an active methylene group is less than 1% by weight, the effect of improving adhesion in the non-dry state may be low, and the water resistance may not be sufficiently improved. Poor curing of the coating layer may occur. In addition, if the radical polymerization initiator (E) having hydrogen abstraction activity is less than 0.1% by weight, the hydrogen abstraction reaction may not proceed sufficiently, and if it exceeds 5.0% by weight, the composition may be contained in the composition. It may not dissolve completely.

  The active energy ray-curable adhesive composition used in the present invention contains 25 to 80% by weight of the radically polymerizable compound (B) when the total amount of the composition is 100% by weight. Furthermore, the active energy ray-curable adhesive composition contains 3 to 40% by weight of the radically polymerizable compound (A) and 5 to 5% of the radically polymerizable compound (C) when the total amount of the composition is 100% by weight. It is preferable to contain 55 weight% and 3-20 weight% of said acrylic oligomer (D).

  In addition, various additives can be added as other optional components to the active energy ray-curable adhesive composition used in the present invention as long as the objects and effects of the present invention are not impaired. Such additives include epoxy resin, polyamide, polyamideimide, polyurethane, polybutadiene, polychloroprene, polyether, polyester, styrene-butadiene block copolymer, petroleum resin, xylene resin, ketone resin, cellulose resin, fluorine-based oligomer, Polymers or oligomers such as silicone-based oligomers and polysulfide-based oligomers; polymerization inhibitors such as phenothiazine and 2,6-di-T-butyl-4-methylphenol; polymerization start assistants; leveling agents; wettability improvers; Agents; plasticizers; UV absorbers; silane coupling agents; inorganic fillers; pigments; dyes, and the like.

  Among the above additives, the silane coupling agent can act on the surface of the polarizer to impart further water resistance. When a silane coupling agent is used, the amount added is usually 0 to 10% by weight, preferably 0 to 5% by weight, most preferably 0 to 3% by weight, based on 100% by weight of the total amount of the composition. .

  As the silane coupling agent, it is preferable to use an active energy ray-curable compound, but the same water resistance can be imparted even if it is not active energy ray-curable.

  Specific examples of the silane coupling agent include, as active energy ray-curable compounds, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, 3-glycide Xylpropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, P-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxy Silane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane and the like can be mentioned.

  Specific examples of silane coupling agents that are not active energy ray curable include N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (Aminoethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N -Phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3 -Mercaptopropylmethyldimethoxysilane, - mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanate propyltriethoxysilane, etc. imidazole silane.

  Preferred are 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane.

  The adhesive layer formed of the active energy ray-curable adhesive composition has higher durability than the water-based adhesive layer. In the present invention, it is preferable to use an adhesive layer having a Tg of 60 ° C. or higher. In addition, it is preferable to control the thickness of the adhesive layer to be 0.01 to 7 μm. Thus, in the polarizing film of the present invention, when using the active energy ray-curable adhesive composition in which the adhesive layer has a high Tg of 60 ° C. or higher, and the thickness of the adhesive layer is controlled within the above range, The durability under severe environment under high humidity and high temperature can be satisfied. In consideration of the durability of the polarizing film, particularly in the present invention, when the Tg (° C.) of the adhesive layer is defined as A, and the thickness (μm) of the adhesive layer is defined as B, Formula (1): A− It is preferable to satisfy 12 × B> 58.

  As described above, the active energy ray-curable adhesive composition is preferably selected such that the Tg of the adhesive layer formed thereby is 60 ° C. or higher, and more preferably 70 ° C. or higher. Furthermore, it is preferable that it is 75 degreeC or more, further 100 degreeC or more, and also 120 degreeC or more. On the other hand, when the Tg of the adhesive layer is too high, the flexibility of the polarizing film is reduced, so the Tg of the adhesive layer is preferably 300 ° C. or less, more preferably 240 ° C. or less, further preferably 180 ° C. or less.

  As described above, the thickness of the adhesive layer is preferably 0.01 to 7 μm, more preferably 0.01 to 5 μm, still more preferably 0.01 to 2 μm, and most preferably 0.01 to 1 μm. If the thickness of the adhesive layer is smaller than 0.01 μm, the cohesion of the adhesive force itself can not be obtained, and the adhesive strength may not be obtained. On the other hand, when the thickness of the adhesive layer exceeds 7 μm, the polarizing film can not satisfy the durability.

  In the polarizing film of the present invention, a transparent protective film is attached to both sides of a polarizer via an adhesive layer formed of a cured product layer of the active energy ray-curable adhesive composition.

  The polarizer is not particularly limited, and various ones can be used. As a polarizer, for example, hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, ethylene / vinyl acetate copolymer-based partially saponified films, etc., dichromatic dyes such as iodine and dichroic dyes, etc. Materials which have been made to adsorb and uniaxially be stretched, and a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrochlorinated product of polyvinyl chloride. Among these, a polarizer made of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 80 μm or less.

  The polarizer which dye | stained the polyvinyl alcohol-type film with iodine, and uniaxially stretched it can be produced by, for example, dyeing | staining by immersing polyvinyl alcohol in the aqueous solution of iodine, and extending | stretching 3 to 7 times of original length. It can also be immersed in an aqueous solution such as boric acid or potassium iodide, if necessary. If necessary, the polyvinyl alcohol-based film may be dipped in water and rinsed before dyeing. In addition to being able to wash the stains and antiblocking agents on the surface of the polyvinyl alcohol film by washing the polyvinyl alcohol film with water, the polyvinyl alcohol film is also effective in preventing nonuniformity such as unevenness in dyeing by swelling the film. is there. The stretching may be performed after staining with iodine, may be stretching while staining, or may be stretched and then stained with iodine. It can also be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

  As a polarizer, a thin polarizer with a thickness of 10 μm or less can be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. It is preferable that such a thin polarizer has less unevenness in thickness, excellent visibility, and less dimensional change, so it is excellent in durability, and furthermore, the thickness as a polarizing film can be reduced. In addition, since a thin polarizer is easy to reduce the moisture content at the time of heat drying, it can be suitably used as a polarizer having a moisture content of less than 15%.

  As a thin polarizer, typically, the specification of Japanese Patent Application Laid-Open Nos. 51-069644, 2000-338329, WO 2010/100917, PCT / JP2010 / 001460, or Japanese Patent Application No. 2010- Examples thereof include thin polarizing films described in Japanese Patent Application Laid-Open No. 269002 and Japanese Patent Application No. 2010-263692. These thin polarizing films can be obtained by a manufacturing method including the steps of stretching a polyvinyl alcohol resin (hereinafter, also referred to as a PVA resin) layer and a stretching resin base material in the state of a laminate and dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it is possible to stretch without any trouble such as breakage due to stretching by being supported by the stretching resin base material.

  Among the thin polarizing films described above, among the processes of stretching in the state of a laminate and the process of dyeing, WO2010 / 100917 pamphlet, in that it can be stretched at high magnification to improve polarization performance. Preferred are those obtained by the process comprising drawing in an aqueous solution of boric acid as described in the specification of JP2010 / 001460, or Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692, particularly What is obtained by the manufacturing method which includes the process of air-drawing auxiliary | assistant before extending | stretching in the boric-acid aqueous solution which is described in Japanese Patent Application No. 2010-269002 specification and Japanese Patent Application No. 2010-263692 specification is preferable.

  The thin high-performance polarizing film described in the specification of the above-mentioned PCT / JP2010 / 001460 is a thin film having a thickness of 7 μm or less made of a PVA-based resin in which a dichroic substance is oriented, which is integrally formed on a resin substrate. It is a highly functional polarizing film, and has optical properties such that the single transmittance is 42.0% or more and the degree of polarization is 99.95% or more.

  The thin high-performance polarizing film forms a PVA-based resin layer on a resin base having a thickness of at least 20 μm by applying and drying a PVA-based resin, and generates a PVA-based resin layer as a dyeing solution of a dichroic substance The PVA-based resin layer, in which the dichroic substance is adsorbed to the PVA-based resin layer and the dichroic substance is adsorbed, is integrated with the resin base in the boric acid aqueous solution, and the total stretch ratio is the original length. It can manufacture by extending | stretching so that it may become 5 times or more of.

  In addition, it is a method for producing a laminate film including a thin high-performance polarizing film in which a dichroic substance is oriented, wherein a resin base having a thickness of at least 20 μm and a PVA based resin on one side of the resin base Forming a laminate film including a PVA-based resin layer formed by applying and drying an aqueous solution, and the laminate including a resin substrate and a PVA-based resin layer formed on one side of the resin substrate A step of causing the PVA-based resin layer contained in the laminate film to adsorb the dichroic substance by immersing the film in a dyeing solution containing the dichroic substance, and a PVA-based resin in which the dichroic substance is adsorbed Stretching the laminate film including the layer in an aqueous solution of boric acid so that the total stretching ratio is at least 5 times the original length, and the PVA-based resin layer on which the dichroic substance is adsorbed is a resin substrate Stretch integrally with Of a thickness of 7 μm or less, a single transmittance of 42.0% or more, and a degree of polarization of 99.95% or more, each consisting of a PVA-based resin layer in which a dichroic substance is oriented on one side of the resin substrate. The thin and highly functional polarizing film can be produced by including the step of producing a laminate film in which the thin and highly functional polarizing film having the optical characteristics of the above is formed.

  The above-mentioned Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692 are thin film polarizing films, which are polarizing films of a continuous web comprising a PVA-based resin in which a dichroic substance is oriented, which is an amorphous ester. A laminate having a PVA-based resin layer formed on a thermoplastic resin base material is stretched in a two-step stretching process consisting of air-assisted stretching and stretching in water in boric acid to a thickness of 10 μm or less It is. Such a thin polarizing film has P>-(100.929T-42.4-1) × 100 (where T <42.3), and P ≧ 99, where T represents the single transmittance and P represents the degree of polarization. It is preferable that the optical characteristics be such as to satisfy the condition of T.9 (where T442.3).

  Specifically, the thin polarizing film is a stretched intermediate composed of a PVA-based resin layer oriented by high-temperature air-stretching with respect to a PVA-based resin layer formed on an amorphous ester-based thermoplastic resin substrate of a continuous web. A colored intermediate product comprising a PVA-based resin layer in which a dichroic substance (iodine or a mixture of iodine and an organic dye is preferred) is formed by the steps of producing a product and adsorbing the dichroic substance to the drawn intermediate product. A thin polarizing film comprising the steps of: producing a colored film; and stretching the colored intermediate product in water with boric acid to produce a polarizing film having a thickness of 10 μm or less, which is composed of a PVA-based resin layer in which a dichroic substance is oriented. It can be manufactured by a manufacturing method.

In this manufacturing method, the total draw ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin base material by in-air high-temperature drawing and in-boric-acid drawing in water is to be 5 times or more. desirable. The liquid temperature of the boric acid aqueous solution for stretching in boric acid can be set to 60 ° C. or more. Before stretching the colored intermediate product in aqueous boric acid solution, it is desirable to insolubilize the colored intermediate product, in which case the colored intermediate product may be treated with an aqueous boric acid aqueous solution whose liquid temperature does not exceed 40 ° C. It is desirable to do by soaking. The amorphous ester-based thermoplastic resin base material is a non-crystalline polyethylene containing a copolymerized polyethylene terephthalate copolymerized with isophthalic acid, a copolymerized polyethylene terephthalate copolymerized with cyclohexane dimethanol, or another copolymerized polyethylene terephthalate. It can be a terephthalate and is preferably made of a transparent resin, and its thickness can be 7 times or more of the thickness of the PVA-based resin layer to be formed. In addition, the draw ratio of the high-temperature drawing in air is preferably 3.5 or less, and the drawing temperature of the high-temperature drawing in air is preferably equal to or higher than the glass transition temperature of the PVA resin, specifically in the range of 95 ° C to 150 ° C. In the case of performing the high temperature airborne stretching by free end uniaxial stretching, the total draw ratio of the PVA resin layer formed on the amorphous ester thermoplastic resin substrate is preferably 5 times or more and 7.5 times or less . In addition, in the case where the high-temperature in-air stretching is performed by fixed-end uniaxial stretching, the total stretch ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin substrate is 5 times or more and 8.5 times or less Is preferred.
More specifically, a thin polarizing film can be produced by the following method.

  A continuous web substrate of isophthalic acid copolymerized polyethylene terephthalate (amorphous PET) copolymerized with 6 mol% of isophthalic acid is prepared. The glass transition temperature of amorphous PET is 75.degree. A laminate consisting of a continuous web amorphous PET substrate and a polyvinyl alcohol (PVA) layer is prepared as follows. Incidentally, the glass transition temperature of PVA is 80 ° C.

  A 200 μm thick amorphous PET substrate and a 4 to 5% PVA aqueous solution prepared by dissolving PVA powder having a degree of polymerization of 1000 or more and a degree of saponification of 99% or more in water are prepared. Next, a PVA aqueous solution is applied to an amorphous PET substrate of 200 μm thickness and dried at a temperature of 50 to 60 ° C. to obtain a laminate in which a PVA layer of 7 μm thickness is formed on the amorphous PET substrate .

  The laminate including the 7 μm-thick PVA layer is subjected to the following steps including air-assisted drawing and a two-step drawing step of drawing in boric acid water to produce a thin highly functional polarizing film of 3 μm thickness. In the first stage of the air-assisted extension process, a laminate including a 7 μm-thick PVA layer is integrally stretched with an amorphous PET substrate to produce a stretched laminate including a 5 μm-thick PVA layer. Specifically, in the stretched laminate, a laminate including a 7 μm-thick PVA layer is subjected to a stretching apparatus placed in an oven set at a stretching temperature environment of 130 ° C., and the draw ratio is 1.8 times The free end is drawn uniaxially. By this stretching process, the PVA layer contained in the stretched laminate is changed to a 5 μm-thick PVA layer in which PVA molecules are oriented.

  Next, in the dyeing step, a colored laminate in which iodine is adsorbed to a 5 μm-thick PVA layer in which PVA molecules are oriented is generated. Specifically, this colored laminate is a single layer transmittance of the PVA layer constituting the high-performance polarizing film finally produced in a dyed solution containing iodine and potassium iodide at a liquid temperature of 30 ° C. Is adsorbed to the PVA layer contained in the stretched laminate by immersion for an arbitrary time so as to be 40 to 44%. In this step, the staining solution contains water as a solvent, an iodine concentration of 0.12 to 0.30% by weight, and a potassium iodide concentration of 0.7 to 2.1% by weight. The ratio of the concentration of iodine to potassium iodide is 1 to 7. By the way, it is necessary to use potassium iodide to dissolve iodine in water. More specifically, by immersing the drawn laminate for 60 seconds in a staining solution having an iodine concentration of 0.30% by weight and a potassium iodide concentration of 2.1% by weight, iodine is added to a 5 μm-thick PVA layer in which PVA molecules are oriented. To produce a colored laminate.

  Further, the second step boric acid in water stretching step further stretches the colored laminate integrally with the amorphous PET substrate to form an optical film laminate including a PVA layer constituting a 3 μm thick high-performance polarizing film Do. Specifically, this optical film laminate is stretched by a stretching device provided in a processing apparatus set in a boric acid aqueous solution containing a boric acid and potassium iodide in a liquid temperature range of 60 to 85 ° C. The free end is uniaxially stretched so that the magnification is 3.3 times. More specifically, the solution temperature of the boric acid aqueous solution is 65 ° C. It also has a boric acid content of 4 parts by weight with respect to 100 parts by weight of water, and a potassium iodide content of 5 parts by weight with respect to 100 parts by weight of water. In this step, the colored laminate whose iodine adsorption amount has been adjusted is first immersed in a boric acid aqueous solution for 5 to 10 seconds. After that, the colored laminate is passed as it is between a plurality of sets of rolls with different circumferential speeds, which are stretching devices disposed in a processing apparatus, and free to have a stretching magnification of 3.3 times over 30 to 90 seconds. Stretches uniaxially at the end. By this stretching process, the PVA layer contained in the colored laminate is changed to a 3 μm-thick PVA layer in which the adsorbed iodine is highly oriented in one direction as a polyiodide ion complex. This PVA layer constitutes a highly functional polarizing film of the optical film laminate.

  Although not a process essential to the production of the optical film laminate, the optical film laminate was taken out of the aqueous boric acid solution by the washing step and attached to the surface of the 3 μm thick PVA layer formed on the amorphous PET substrate It is preferred to wash the boric acid with aqueous potassium iodide. Thereafter, the washed optical film laminate is dried by a hot air drying process at 60.degree. The cleaning step is a step for eliminating appearance defects such as boric acid precipitation.

  Similarly, the adhesive is not applied to the surface of a 3 μm-thick PVA layer formed on an amorphous PET substrate by a lamination and / or transfer step although it is not necessarily an essential step for producing an optical film laminate. However, after laminating an 80 μm thick triacetyl cellulose film, the non-crystalline PET substrate can be peeled off, and a 3 μm thick PVA layer can be transferred to an 80 μm thick triacetyl cellulose film.

[Other process]
The method for producing a thin polarizing film described above may include other steps in addition to the above steps. As another process, an insolubilization process, a crosslinking process, a drying (control of a moisture content) process etc. are mentioned, for example. The other steps may be performed at any appropriate timing.
The insolubilization step is typically performed by immersing the PVA-based resin layer in a boric acid aqueous solution. Water resistance can be imparted to the PVA-based resin layer by performing the insolubilization treatment. The concentration of the aqueous boric acid solution is preferably 1 part by weight to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilization bath (boric acid aqueous solution) is preferably 20 ° C to 50 ° C. Preferably, the insolubilization step is performed after the preparation of the laminate and before the dyeing step or the in-water stretching step.
The crosslinking step is typically performed by immersing the PVA-based resin layer in a boric acid aqueous solution. Water resistance can be given to a PVA-type resin layer by giving a crosslinking process. The concentration of the aqueous boric acid solution is preferably 1 part by weight to 4 parts by weight with respect to 100 parts by weight of water. Moreover, when performing a bridge | crosslinking process after the said dyeing | staining process, it is preferable to mix | blend iodide further. By blending an iodide, elution of iodine adsorbed to the PVA-based resin layer can be suppressed. The compounding amount of iodide is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. Specific examples of iodide are as described above. The liquid temperature of the crosslinking bath (boric acid aqueous solution) is preferably 20 ° C to 50 ° C. Preferably, the crosslinking step is performed before the second in-boric-water stretching step. In a preferred embodiment, the dyeing step, the crosslinking step and the second stretching step in water in boric acid are performed in this order.

  In the method for producing a polarizing film according to the present invention, a thin polarizer formed on one side of a resin substrate can be suitably used as a polarizer. FIG. 3: shows an example of the manufacturing method of the polarizing film which concerns on this invention provided with the thin-shaped polarizer as a polarizer. In the example shown in FIG. 3, a first coating step of coating the active energy ray-curable adhesive composition on the bonding surface of the first transparent protective film 2 to the thin polarizer 1 and one side of the resin substrate Thin film polarizer 1 and a laminate film (the resin substrate is not shown in FIG. 3, but the resin substrate is laminated on the lower layer side of the thin polarizer 1). 1) A first bonding step of bonding the transparent protective film 2 is performed. Next, the thin polarizer 1 and the first transparent protective film 2 are bonded by irradiating the active energy ray from the side of the first transparent protective film 2 using the active energy ray irradiator 5A (first bonding Process). Next, the resin substrate is peeled off from the thin polarizer 1 (peeling step). Next, a second coating step of applying an active energy ray-curable adhesive composition to the bonding surface of the second transparent protective film 3 with the thin polarizer 1 and a resin base of the thin polarizer 1 The 2nd bonding process of bonding the thin polarizer 1 and the 2nd transparent protective film 3 is implemented from the surface side of the side which peeled. Next, the thin polarizer 1 and the second transparent protective film 3 are bonded by irradiating the active energy ray from the second transparent protective film 3 side using the active energy ray irradiator 5B (second bonding (second bonding) Process). Thereby, the polarizing film provided with the thin-shaped polarizer 1 can be manufactured.

As a material for forming a transparent protective film provided on one side or both sides of the above-mentioned polarizer, a material excellent in transparency, mechanical strength, heat stability, water blocking property, isotropy and the like is preferable, and particularly, the moisture permeability is 150 g / ^m, more preferably not more 2 / 24h or less, particularly preferably those following 140 g ^/ m 2 / 24h, further preferably the following 120 g ^/ m 2 / 24h. The moisture permeability is determined by the method described in the examples.

  The thickness of the transparent protective film can be appropriately determined, but generally it is about 1 to 500 μm, preferably 1 to 300 μm, more preferably 5 to 200 μm from the viewpoints of strength, workability such as handleability, thin layer property and the like. preferable. Furthermore, 10-200 micrometers is preferable and 20-80 micrometers is preferable.

  Examples of materials for forming the transparent protective film satisfying the low moisture permeability include polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; arylate resins; amide resins such as nylon and aromatic polyamide; polyethylene and polypropylene A polyolefin polymer such as ethylene / propylene copolymer, a cyclic olefin resin having a cyclo or norbornene structure, a (meth) acrylic resin, or a mixture thereof can be used. Among the above resins, polycarbonate resins, cyclic polyolefin resins and (meth) acrylic resins are preferable, and cyclic polyolefin resins and (meth) acrylic resins are particularly preferable.

  As a specific example of cyclic polyolefin resin, Preferably it is norbornene-type resin. The cyclic olefin-based resin is a generic term for resins polymerized by using cyclic olefin as a polymerization unit, and is described, for example, in JP-A-1-240517, JP-A-3-14882 and JP-A-3-122137. Resin is mentioned. Specific examples include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins, Α-olefins such as ethylene and propylene, and copolymers thereof (typically random copolymers), And graft polymers obtained by modifying these with unsaturated carboxylic acids and their derivatives, and hydrides thereof. A norbornene-type monomer is mention | raise | lifted as a specific example of cyclic olefin.

  Various products are marketed as cyclic polyolefin resin. As a specific example, the trade name "Zeonex" made by Nippon Zeon Co., Ltd., "Zeonor", the trade name "Arton" made by JSR Co., the trade name "Torpus" made by TICONA, the trade name made by Mitsui Chemical Co., Ltd. "APEL" is mentioned.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or more, more preferably 120 ° C. or more, still more preferably 125 ° C. or more, particularly preferably 130 ° C. or more. When the Tg is 115 ° C. or more, the durability of the polarizing plate can be excellent. The upper limit of the Tg of the (meth) acrylic resin is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of formability and the like. From the (meth) acrylic resin, a film having an in-plane retardation (RE) and a thickness direction retardation (RTH) of substantially zero can be obtained.

As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, methyl (meth) acrylate-styrene copolymer (MS resin etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylic acid norbornyl copolymer and the like). Preferably, poly (meth) acrylic acid C1-6 alkyl such as methyl poly (meth) acrylate is mentioned. More preferably, a methyl methacrylate based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) can be mentioned.

  Specific examples of the (meth) acrylic resin include, for example, (meth) acrylic resin having a ring structure in the molecule described in Acripet VH or Acripet VRL 20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A No. 2004-70296. And high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  A (meth) acrylic resin having a lactone ring structure can also be used as the (meth) acrylic resin. It is because it has high heat resistance, high transparency, and high mechanical strength by biaxial stretching.

  Examples of the (meth) acrylic resin having a lactone ring structure include Japanese Patent Application Laid-Open Nos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, and 2005- Examples thereof include (meth) acrylic resins having a lactone ring structure described in JP-A-146084 and the like.

  In addition, as the transparent protective film of low moisture permeability provided on both sides of the polarizer, transparent protective films made of the same polymer material may be used on the front and back, and even if transparent protective films made of different polymer materials etc. are used. Good.

  As the transparent protective film, a retardation plate having a front retardation of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The in-plane retardation is usually controlled in the range of 40 to 200 nm, and the thickness direction retardation is usually controlled in the range of 80 to 300 nm. When using a retardation plate as a transparent protective film, since the said retardation plate functions also as a transparent protective film, thickness reduction can be achieved.

  Examples of the retardation plate include a birefringent film formed by uniaxially or biaxially stretching a polymer material, an alignment film of liquid crystal polymer, and a film supporting an alignment layer of liquid crystal polymer. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  In addition, the film which has the said phase difference can be separately bonded together to the transparent protective film which does not have a phase difference, and the said function can be provided.

  A functional layer such as a hard coat layer, an antireflective layer, an antisticking layer, a diffusion layer or an antiglare layer can be provided on the surface of the transparent protective film to which the polarizer is not attached. The functional layers such as the hard coat layer, the antireflective layer, the antisticking layer, the diffusion layer, and the antiglare layer can be provided on the transparent protective film itself, or separately provided separately from the transparent protective film. It can also be done.

  The polarizing film of the present invention can be used as an optical film laminated with other optical layers in practical use. The optical layer is not particularly limited, but, for example, for the formation of a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including a wave plate such as 1/2 or 1/4), a viewing angle compensation film One or two or more optical layers may be used. In particular, a reflective polarizing film or a semitransparent polarizing film in which a reflecting plate or a semitransparent reflecting plate is further laminated to the polarizing film of the present invention, an elliptically polarizing film in which a retardation plate is further laminated to a polarizing film or circularly polarized light A film, a wide viewing angle polarizing film in which a viewing angle compensation film is further laminated on a polarizing film, or a polarizing film in which a brightness enhancement film is further laminated on a polarizing film is preferable.

  An optical film in which the above optical layer is laminated on a polarizing film can also be formed by a method of sequentially laminating separately in the production process of a liquid crystal display device or the like. It is excellent in stability, assembly work, etc., and there is an advantage which can improve manufacturing processes, such as a liquid crystal display. An appropriate adhesive means such as an adhesive layer may be used for lamination. When bonding the above-mentioned polarizing film and other optical films, their optical axes can be set at appropriate arrangement angles in accordance with the target retardation characteristics and the like.

  A pressure-sensitive adhesive layer for bonding to another member such as a liquid crystal cell can also be provided on the above-described polarizing film or an optical film in which at least one polarizing film is laminated. The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited, but, for example, those having an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as a base polymer are appropriately selected. Can be used. In particular, those having excellent optical transparency such as acrylic pressure-sensitive adhesives, exhibiting appropriate wettability, cohesion, and adhesive properties such as adhesiveness, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  The pressure-sensitive adhesive layer can also be provided on one side or both sides of a polarizing film or an optical film as an overlapping layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesion layers, such as a different composition, a kind, and thickness, in the front and back of a polarizing film or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength and the like, and is generally 1 to 500 μm, preferably 1 to 200 μm, and particularly preferably 1 to 100 μm.

  The exposed surface of the adhesive layer is temporarily attached and covered with a separator for the purpose of preventing contamination and the like until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, suitable thin sheets such as plastic films, rubber sheets, paper, cloths, non-woven fabrics, nets, foamed sheets and metal foils, laminates thereof, silicone-based or long as required A suitable one according to the prior art may be used, such as one coated with a suitable release agent such as chain alkyl type, fluorine type or molybdenum sulfide.

  The polarizing film or the optical film of the present invention can be preferably used for forming various devices such as liquid crystal display devices. The formation of the liquid crystal display can be performed according to the prior art. That is, in general, a liquid crystal display device is formed by appropriately assembling components such as a liquid crystal cell, a polarizing film or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no particular limitation except that the polarizing film or the optical film according to the invention is used, and the conventional method can be applied. The liquid crystal cell may also be of any type such as TN type, STN type, or wedge type.

  It is possible to form a suitable liquid crystal display device such as a liquid crystal display device in which a polarizing film or an optical film is disposed on one side or both sides of a liquid crystal cell, or a lighting system using a backlight or a reflector. In that case, the polarizing film or the optical film according to the present invention can be disposed on one side or both sides of the liquid crystal cell. When providing a polarizing film or an optical film on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, one or more appropriate components such as a diffusion plate, antiglare layer, anti-reflection film, protective plate, prism array, lens array sheet, light diffusion plate, and back light at appropriate positions. Two or more layers can be arranged.

  Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto.

<Tg: Glass transition temperature>
Tg was measured under the following measurement conditions using a TA Instruments dynamic viscoelasticity measuring device RSA III.
Sample size: Width 10 mm, length 30 mm,
Clamp distance 20 mm,
Measurement mode: tension, frequency: 1 HZ, temperature rising rate: 5 ° C./minute Measurement of dynamic viscoelasticity was performed, and it was adopted as temperature Tg of the peak top of tan δ.

Moisture Permeability of Transparent Protective Film
The moisture permeability was measured according to the moisture permeability test (cup method) of JIS Z0208. A sample cut to a diameter of 60 mm was set in a moisture-permeable cup containing about 15 G of calcium chloride, and the temperature was 40 ° C., the humidity was 90%, and the temperature was 90%. H. The placed in a constant temperature machine, to determine the moisture permeability by measuring the weight increase of calcium chloride before and after allowing to stand for 24 hours ^{(g / m 2 / 24h)} .

<Transparent Protective Film>
A biaxially stretched film of a 55 [mu] m thick norbornene resin (trade name: Zeonor, manufactured by Nippon Zeon Co., Ltd.) was used as a UV transmitting transparent protective film having a light transmittance of 80% or more at a wavelength of 365 nm. 91.1% The light transmittance of the wavelength 365nm of the norbornene resin film, the moisture permeability is ^{11 (g / m 2 / 24h} ), a front retardation is 55 nm, the thickness direction retardation was 135 nm.
In addition, a 60 μm thick triacetyl cellulose film (TAC) (SP value 23.3) is subjected to saponification / corona treatment etc. as an ultraviolet ray impermeable type transparent protective film having a light transmittance of less than 5% at a wavelength of 365 nm. (A TAC which has not been subjected to saponification, corona treatment, etc. is also referred to as "untreated TAC"). The untreated TAC 0.1% is the light transmittance of wavelength 365nm of the film, the moisture permeability was ^{507 (g / m 2 / 24h} ).

<Active energy ray>
As active energy rays, visible light (gallium filled metal halide lamp) Irradiator: FUSION UV SYSTEMS, INC. LIGHT HAMMER 10 manufactured by INC. Bulb: V bulb peak illuminance: 1600 mW / cm ² , integrated dose 1000 / mJ / cm ²
(Wavelength of 380-440 nm) was used. In addition, the illumination intensity of visible light was measured using SOLA-CHECK system SOLA-CHECK system.

(Preparation of active energy ray-curable adhesive composition)
Each component used is as follows.

(1) Radically polymerizable compound (A)
HEAA (hydroxyethyl acrylamide), SP value 29.6, homopolymer Tg 123 ° C., Kojin Co., Ltd. (2) radically polymerizable compound (B)
ARONIX M-220 (M-220) (tripropylene glycol diacrylate), SP value 19.0, homopolymer Tg 69 ° C., Toagosei Co., Ltd. (3) radically polymerizable compound (C)
ACMO (Acryloyl morpholine), SP value 22.9, Tg of homopolymer of 150 ° C., Kojin Co., Ltd. (4) Acrylic oligomer (D) obtained by polymerizing (meth) acrylic monomer
ARUFON UP-1190 (UP-1190), manufactured by Toagosei Co., Ltd. (5) AAEM (2-acetoacetoxyethyl methacrylate), SP value 20.23 (MJ / M ³ ) ^1/2 , homopolymer Tg 9 ° C., Japan synthesis Chemical compound (6) compound represented by general formula (1) KAYACURE DETX-S (DETX-S) (diethyl thioxanthone), Nippon Kayaku Co., Ltd. (7) photopolymerization initiator (general formula (2) Compounds to be
IRGACURE 907 (IRG 907) (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), manufactured by BASF

Example 1
As an active energy ray-curable adhesive composition, HEAA / M-220 / ACMO / UP-1190 / AAEM / IRGACURE 907 / KAYACURE DETX-S = 16.4 / 32.8 / 32.8 / 8.2 / 5. 7 / 2.5 / 1.6 (The numerical value is a weight% when the total amount of the composition is 100% by weight) and mixed, and stirred at 50 ° C. for 1 hour to prepare an active energy ray-curable adhesive composition did.

(Production of thin polarizing film X and production of polarizing film using it)
In order to produce the thin polarizing film X, first, a laminate obtained by forming a PVA layer having a thickness of 24 μm on an amorphous PET substrate is formed into a stretched laminate by air-assisted stretching at a stretching temperature of 130 ° C. The stretched laminate is dyed to form a colored laminate, and the colored laminate is stretched integrally with the amorphous PET substrate so as to have a total stretch ratio of 5.94 times by stretching in water at a stretching temperature of 65 ° C. An optical film laminate was produced comprising a 10 μm thick PVA layer. The PVA molecules of the PVA layer formed on the amorphous PET substrate by such two-step drawing are oriented in high order, and the iodine adsorbed by dyeing is oriented in one direction in one direction as polyiodine ion complex An optical film laminate including a 10 μm-thick PVA layer constituting the high-performance polarizing film X could be produced. Further, the active energy ray-curable adhesive composition was coated on a norbornene resin film (first transparent protective film, ultraviolet transparent transparent protective film) using an MCD coater (Fuji Machinery Co., Ltd.) (cell shape: honeycomb, number of gravure roll wires) Coating is performed to a thickness of 0.5 μm using 1000 pieces / INCH, rotational speed 140% / pair line speed) (first coating step), and thin polarization of the optical film laminate from the adhesive coated surface It bonded together on the surface of the film | membrane X (moisture content 5.0%) (1st bonding process). Next, an active energy ray was irradiated from the norbornene resin film (first transparent protective film) side to cure the active energy ray-curable adhesive composition (first bonding step). Next, the amorphous PET substrate was peeled off from the thin polarizing film X (peeling step). Furthermore, an active energy ray-curable adhesive composition is applied to the side of the thin polarizing film X from which the amorphous PET substrate has been peeled off (second coating step), and the untreated side from the coated surface side A TAC film (second transparent protective film, ultraviolet ray impermeable transparent protective film) was laminated (second bonding step). Next, after an active energy ray is irradiated from the untreated TAC film (second transparent protective film) side to cure the active energy ray-curable adhesive composition (second bonding step), hot air drying is performed at 70 ° C. for 3 minutes. Thus, a polarizing film was produced. The line speed of bonding was 25 m / min. The adhesive force of the obtained polarizing film and curl evaluation were evaluated based on the following conditions.

Example 2
A polarizing film was produced in the same manner as in Example 1 except that an untreated TAC film was used as the first transparent protective film and a norbornene resin film was used as the second transparent protective film.

Example 3
The polarizing film was manufactured by the method similar to Example 1 except having used the un-processed TAC film as a 1st transparent protective film and a 2nd transparent protective film.

Example 4
The polarizing film was manufactured by the method similar to Example 1 except having implemented the 1st adhesion process after the 2nd bonding process.

Comparative Example 1
The active energy ray is irradiated only from the norbornene resin film (first transparent protective film) side, and the active energy ray is not irradiated from the untreated TAC film (second transparent protective film) side, that is, one step similar to the prior art A polarizing film was manufactured in the same manner as in Example 1 except that the irradiation was performed.

<Adhesive force>
The polarizing film was cut out to a size of 200 mm in parallel with the stretching direction of the polarizer and 20 mm in the orthogonal direction, and the polarizing film was bonded to a glass plate. A cut is made with a cutter knife between the transparent protective film and the polarizer (SP value 32.8), and the protective film and the polarizer are peeled at a peeling speed of 500 mm / min in 90 ° direction by tensilon, and the peeling strength Was measured. Moreover, the infrared absorption spectrum of the peeling surface after peeling was measured by ATR method, and the peeling interface was evaluated based on the following reference | standard.
A: cohesive failure of the protective film B: interfacial peeling between the protective film / adhesive layer C: interfacial peeling between the adhesive layer / polarizer D: cohesive failure of the polarizer In the above criteria, A and D indicate that the adhesive force is a film It means that the adhesive strength is very excellent because it is more than the cohesion of On the other hand, B and C mean that the adhesion at the protective film / adhesive layer (adhesive layer / polarizer) interface is insufficient (adhesion is poor). Taking these into consideration, the adhesive force in the case of A or D is ○, A · B (“cohesive failure of the protective film” and “interfacial peeling between the protective film / adhesive layer” occur simultaneously) or A · C The adhesive force in the case of (the “cohesive failure of the protective film” and the “interfacial peeling between the adhesive layer / polarizer” occur simultaneously) is Δ, and the adhesive force in the case of B or C is x.

<Curl property evaluation of polarizing film>
A sample of 100 mm × 150 mm was cut out so that the long side of the polarizing plate was in the stretching direction. The convex surface was placed on a horizontal surface, and the distance from the horizontal surface at four ends of the sample was measured. At this time, curling is suppressed and the case where the average value of four places is less than 30 mm is set as the usable level (o) as a polarizing plate. On the other hand, a case where the average value exceeds 30 mm is regarded as an unusable level (x) as a polarizing plate in which the curl is remarkable.

Claims (20)

A method for producing a polarizing film, wherein a first transparent protective film is provided on one side of a polarizer and a second transparent protective film is provided on the other side via an adhesive layer,
At least one surface of one side of the polarizer or the side of the first transparent protective film to be bonded to one side of the polarizer, and the other surface of the polarizer or the polarizer of the second transparent protective film A coating step of coating an active energy ray-curable adhesive composition on at least one surface of the side to be bonded to the other surface,
A bonding step of bonding the polarizer and the first transparent protective film, and a bonding step of bonding the polarizer and the second transparent protective film;
First, the active energy ray is irradiated from the first transparent protective film side, and then the active energy ray is irradiated from the second transparent protective film side to cure the active energy ray-curable adhesive composition. And a bonding step of bonding the polarizer and the first transparent protective film, and the polarizer and the second transparent protective film via the obtained adhesive layer.
An acrylic oligomer (D) formed by polymerizing a (meth) acrylic monomer with the radically polymerizable compounds (A), (B) and (C) as a curable component, and the active energy ray-curable adhesive composition Contains and
The radical polymerizable compound (A) has an SP value of 29.0 (MJ / m ³ ) ^1/2 or more and 32.0 (MJ / m ³ ) ^1/2 or less,
The radical polymerizable compound (B) has an SP value of 18.0 (MJ / m ³ ) ^1/2 or more and 21.0 (MJ / m ³ ) ^{1/2 or} less.
The radical polymerizable compound (C) has an SP value of 21.0 (MJ / m ³ ) ^1/2 or more and 23.0 (MJ / m ³ ) ^1/2 or less.
The method for producing a polarizing film, wherein the radical polymerizable compound (B) is contained in an amount of 25 to 80% by weight based on 100% by weight of the total amount of the composition.   The polarizing film according to claim 1, wherein the first transparent protective film has a light transmittance of a wavelength of 365 nm of 80% or more, and the second transparent protective film has a light transmittance of a wavelength of 365 nm of less than 5%. Production method.   The method for producing a polarizing film according to claim 1, wherein the first transparent protective film and the second transparent protective film have a light transmittance of less than 5% at a wavelength of 365 nm.   The method for producing a polarizing film according to claim 1, wherein the first transparent protective film and the second transparent protective film have a light transmittance of 80% or more at a wavelength of 365 nm.   The method for producing a polarizing film according to any one of claims 1 to 4, wherein the active energy ray includes visible light in a wavelength range of 380 to 450 nm.   The polarizing film according to any one of claims 1 to 5, wherein the active energy ray has a ratio of integrated illuminance in a wavelength range of 380 to 440 nm and integrated illuminance in a wavelength range of 250 to 370 nm in a range of 100: 0 to 100: 50. Production method.   The method for producing a polarizing film according to any one of claims 1 to 6, wherein the active energy ray uses a gallium lamp as a light source and blocks ultraviolet rays of 380 nm or less using a band pass filter. A compound represented by the following general formula (1) as an active energy ray-curable adhesive composition as a photopolymerization initiator;

(Wherein R ¹ and R ^{2 each} represent —H, —CH ₂ CH ₃ , —IPr or Cl, and R ¹ and R ² may be the same or different) The manufacturing method of the polarizing film as described in-. A compound further represented by the following general formula (2) as a photopolymerization initiator;

(Wherein, R ³ , R ⁴ and R ^{5 each} represent —H, —CH ₃ , —CH ₂ CH ₃ , —IPr or Cl, and R ³ , R ⁴ and R ⁵ may be the same or different) The manufacturing method of the polarizing film of Claim 8 containing.   The total thickness of the said polarizing film is 150 micrometers or less, The manufacturing method of the polarizing film in any one of Claims 1-9. The manufacturing method of the polarizing film in any one of Claims 1-10 containing the radically polymerizable compound which has an active methylene group, and the radical polymerization initiator (E) which has a hydrogen abstraction effect | action. The method for producing a polarizing film according to claim 11, wherein the active methylene group is an acetoacetyl group. The method for producing a polarizing film according to claim 11 or 12, wherein the radically polymerizable compound having an active methylene group is acetoacetoxyalkyl (meth) acrylate. The method for producing a polarizing film according to any one of claims 11 to 13, wherein the radical polymerization initiator (E) is a thioxanthone radical polymerization initiator. The composition according to claim 11, containing 1 to 50% by weight of the radically polymerizable compound having an active methylene group and 0.1 to 10% by weight of the radical polymerization initiator (E) when the total amount of the composition is 100% by weight. The manufacturing method of the polarizing film in any one of 14.   When the total amount of the composition is 100% by weight, 3 to 40% by weight of the radically polymerizable compound (A), 5 to 55% by weight of the radically polymerizable compound (C), and 3 of the acrylic oligomer (D) The manufacturing method of the polarizing film in any one of Claims 1-15 containing -20 weight%.   The glass transition temperature (Tg) of the homopolymer of each of the said radically polymerizable compounds (A), (B) and (C) is 60 degreeC or more, manufacture of the polarizing film in any one of Claims 1-16. Method.   The method for producing a polarizing film according to any one of claims 1 to 17, wherein the radically polymerizable compound (A) is hydroxyethyl acrylamide and / or N-methylol acrylamide.   The method for producing a polarizing film according to any one of claims 1 to 18, wherein the radically polymerizable compound (B) is tripropylene glycol diacrylate.   The method for producing a polarizing film according to any one of claims 1 to 19, wherein the radically polymerizable compound (C) is acryloyl morpholine and / or N-methoxymethyl acrylamide.

Images