阅读说明：本技术 偏振膜及其制造方法、光学膜、以及图像显示装置 (Polarizing film, method for producing same, optical film, and image display device ) 是由 菅野亮 冈本昌之 大学纪二 山崎达也 于 2019-02-19 设计创作，主要内容包括：本发明提供能够兼顾抑制起偏镜在加湿环境中的光学特性降低、和在例如实施了小直径凹R加工、小直径孔加工的异形偏振膜中特别要求的优异的裂纹耐久性的偏振膜及其制造方法。上述偏振膜在起偏镜的至少一面隔着由固化物层形成的粘接剂层设置有纤维素类树脂膜作为透明保护膜,上述固化物层是对活性能量射线固化型粘接剂组合物照射活性能量射线而成的,将上述活性能量射线固化型粘接剂组合物总量设为100重量％时,该组合物以给定量分别含有SP值为29.0(MJ/m<Sup>3</Sup>)<Sup>1/2</Sup>以上且32.0(MJ/m<Sup>3</Sup>)<Sup>1/2</Sup>以下、SP值为18.0(MJ/m<Sup>3</Sup>)<Sup>1/2</Sup>以上且小于21.0(MJ/m<Sup>3</Sup>)<Sup>1/2</Sup>、及SP值为21.0(MJ/m<Sup>3</Sup>)<Sup>1/2</Sup>以上且26.0(MJ/m<Sup>3</Sup>)<Sup>1/2</Sup>以下的活性能量射线固化型化合物(A)、(B)、及(C)。(The invention providesA polarizing film and a method for producing the same are provided, which can simultaneously achieve excellent crack durability required particularly for a special-shaped polarizing film subjected to small-diameter recess R processing and small-diameter hole processing while suppressing a decrease in optical characteristics of a polarizer in a humidified environment. The polarizing film is provided with a cellulose resin film as a transparent protective film on at least one surface of a polarizer via an adhesive layer formed by a cured product layer, the cured product layer is formed by irradiating an active energy ray-curable adhesive composition with active energy rays, and the composition contains 29.0 SP value (MJ/m) in a given amount when the total amount of the active energy ray-curable adhesive composition is 100 wt% 3 ) 1/2 32.0 (MJ/m) of the above 3 ) 1/2 The SP value was 18.0 (MJ/m) or less 3 ) 1/2 Above and less than 21.0 (MJ/m) 3 ) 1/2 And SP value of 21.0 (MJ/m) 3 ) 1/2 Above and 26.0 (MJ/m) 3 ) 1/2 The active energy ray-curable compounds (A), (B) and (C) below.)

1. A polarizing film comprising a polarizer and a transparent protective film provided on at least one surface of the polarizer via an adhesive layer,

the transparent protective film is a cellulose-based resin film,

the adhesive layer is formed of a cured product layer obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray,

the active energy ray-curable adhesive composition contains, when the total amount of the active energy ray-curable adhesive composition is 100 wt%:

SP value of 29.0 (MJ/m)³)^1/232.0 (MJ/m) of the above³)^1/20.0 to 4.0 wt% of the following active energy ray-curable compound (A),

SP value 18.0 (MJ/m)³)^1/2Above and less than 21.0 (MJ/m)³)^1/25.0 to 98.0 wt% of the active energy ray-curable compound (B), and

SP value of 21.0 (MJ/m)³)^1/2Above and 26.0 (MJ/m)³)^1/2The active energy ray-curable compound (C) is 5.0 to 98.0 wt%.

2. The polarizing film of claim 1,

the polarizer has a thickness of 3 to 15 [ mu ] m.

3. The polarizing film according to claim 1 or 2,

the active energy ray-curable adhesive composition contains 20 to 80 wt% of the active energy ray-curable compound (B) based on 100 wt% of the total amount of the active energy ray-curable adhesive composition.

4. The polarizing film according to any one of claims 1 to 3,

the active energy ray-curable adhesive composition contains an acrylic oligomer (D) obtained by polymerizing a (meth) acrylic monomer.

5. The polarizing film according to any one of claims 1 to 4,

an acryloyl equivalent C of the active energy ray-curable adhesive composition represented by the following formula (1)_aeThe content of the organic acid is more than 140,

C_ae＝1/Σ(W_N/N_ae) (1)

in the formula (1), W_NIs the mass fraction of the active energy ray-curable compound N in the composition, N_aeThe acryloyl equivalent weight of the active energy ray-curable compound N.

6. The polarizing film according to any one of claims 1 to 5,

the active energy ray-curable adhesive composition contains a radical polymerization initiator having a hydrogen abstraction effect.

7. The polarizing film of claim 6,

the free radical polymerization initiator is a thioxanthone free radical polymerization initiator.

8. The polarizing film according to any one of claims 1 to 7,

the active energy ray-curable adhesive composition contains an acrylic oligomer (D),

a compatible layer whose composition changes continuously is formed between the transparent protective film and the adhesive layer,

when the thickness of the compatible layer is P (mum) and the content of the acrylic oligomer (D) is Q wt% when the total amount of the composition is 100 wt%, the value of P x Q is less than 10.

9. The polarizing film according to any one of claims 1 to 8,

a compound represented by the following general formula (1) is provided on at least one of the surfaces to be bonded of the polarizer and the transparent protective film,

wherein X is a functional group containing a reactive group, R¹And R²Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group or a heterocyclic group,

the compound represented by the general formula (1) is interposed between the polarizer and the adhesive layer, and/or between the transparent protective film and the adhesive layer.

10. The polarizing film of claim 9,

the compound represented by the general formula (1) is a compound represented by the following general formula (1'),

wherein Y is an organic group, X, R¹And R²The same as above.

11. The polarizing film of claim 9 or 10,

the polarizing plate is provided with a compound represented by the general formula (1) on the bonding surface of the polarizer.

12. The polarizing film according to any one of claims 9 to 11,

the reactive group of the compound represented by the general formula (1) is at least 1 reactive group selected from an α, β -unsaturated carbonyl group, a vinyl ether group, an epoxy group, an oxetanyl group, an amino group, an aldehyde group, a mercapto group, and a halogen group.

13. A method for manufacturing a polarizing film, comprising:

a coating step of coating an active energy ray-curable adhesive composition on at least one surface of the polarizer and the transparent protective film;

a bonding step of bonding the polarizer and the transparent protective film; and

an adhesion step of irradiating the polarizer or the transparent protective film with an active energy ray from the polarizer side or the transparent protective film side to adhere the polarizer and the transparent protective film via an adhesive layer obtained by curing the active energy ray-curable adhesive composition,

the transparent protective film is a cellulose-based resin film,

the active energy ray-curable adhesive composition contains, when the total amount of the active energy ray-curable adhesive composition is 100 wt%:

SP value of 29.0 (MJ/m)³)^1/232.0 (MJ/m) of the above³)^1/20.0 to 4.0 wt% of the following active energy ray-curable compound (A),

SP value 18.0 (MJ/m)³)^1/2Above and less than 21.0 (MJ/m)³)^1/25.0 to 98.0 wt% of the active energy ray-curable compound (B), and

SP value of 21.0 (MJ/m)³)^1/2Above and 26.0 (MJ/m)³)^1/2The active energy ray-curable compound (C) is 5.0 to 98.0 wt%.

14. The polarizing film production method according to claim 13,

the polarizer has a thickness of 3 to 15 [ mu ] m.

15. The method for manufacturing a polarizing film according to claim 13 or 14, comprising:

an easy adhesion treatment step of adhering a compound represented by the following general formula (1) to at least one of the adhesion surfaces of the polarizer and the transparent protective film,

wherein X is a functional group containing a reactive group, R¹And R²Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group, or a heterocyclic group.

16. The method for producing a polarizing film according to any one of claims 13 to 15,

the compound represented by the general formula (1) is a compound represented by the following general formula (1'),

wherein Y is an organic group, X, R¹And R²The same as above.

17. The polarizing film production method according to any one of claims 13 to 16,

before the coating process, the surface of one side to be attached is subjected to corona treatment, plasma treatment, excimer treatment or flame treatment, and the surface of one side to be attached is at least one surface of the polarizer and the transparent protective film.

18. The method for producing a polarizing film according to any one of claims 13 to 17,

the active energy ray comprises visible light with the wavelength range of 380-450 nm.

19. The method for producing a polarizing film according to any one of claims 13 to 18,

the ratio of the cumulative illumination intensity of the active energy ray in the wavelength range of 380-440 nm to the cumulative illumination intensity in the wavelength range of 250-370 nm is 100: 0-100: 50.

20. An optical film comprising at least 1 polarizing film according to any one of claims 1 to 12 laminated thereon.

21. An image display device using the polarizing film according to any one of claims 1 to 12 and/or the optical film according to claim 20.

Technical Field

The present invention relates to a polarizing film having a transparent protective film provided on at least one surface of a polarizer with an adhesive layer interposed therebetween, and a method for producing the same. The polarizing film may be used alone or in combination with an optical film of the polarizing film to form an image display device such as a Liquid Crystal Display (LCD), an organic EL display, a CRT, or a PDP.

Background

In various image display devices, a polarizing film is used for displaying an image. For example, in a Liquid Crystal Display (LCD), it is essential to dispose polarizing films on both sides of a glass substrate forming a surface of a liquid crystal panel in view of an image forming method thereof. In the organic EL display device, a circular polarizing film in which a polarizing film and an 1/4 wave plate are laminated is disposed on the visible side of the organic light-emitting layer in order to block specular reflection of external light at the metal electrode.

As the polarizing film, a polarizing plate in which a protective film is attached to one surface or both surfaces of a polarizer made of a dichroic material such as a polyvinyl alcohol-based film and iodine with a polyvinyl alcohol-based adhesive, an active energy ray-curable adhesive, or the like is generally used.

The above polarizing film has a problem that cracks (through cracks) are easily generated in the entire absorption axis direction of the polarizer due to a change in shrinkage stress of the polarizer in a severe environment of thermal shock (for example, a thermal shock test in which temperature conditions of-40 ℃ and 85 ℃ are repeated). Therefore, in order to suppress shrinkage of the polarizer and reduce the influence of thermal shock, if the polarizer is a thin polarizer having a thickness of 10 μm or less, the change in shrinkage stress is small, and therefore, through cracks are less likely to occur. For example, a polarizing film in which a protective film is attached to one surface or both surfaces of a thin polarizer having a thickness of 10 μm or less to suppress the occurrence of through cracks is disclosed (for example, see patent document 1 below).

On the other hand, a thin polarizer having a thickness of 10 μm or less has a problem that optical characteristics are liable to be degraded in a humidified environment. Therefore, in patent document 2, a resin film having a very low moisture permeability is used as a protective film for the thin polarizer, thereby suppressing deterioration of the thin polarizer due to humidification of the thin polarizer.

In recent years, polarizing plates have been used in instrument displays of automobiles, smartwatches, and the like, and it is also desired to use polarizing plates having shapes other than rectangular shapes and form through holes in polarizing plates, for example, in view of design properties and the like (see, for example, patent document 3 below). It was found that in such a special-shaped working, the demand for finer and more sophisticated working treatments and more complicated working treatments, which have not been found before, is increased, and there are cases where small-diameter recess R working and small-diameter hole working are performed, and there is a tendency that cracks are more likely to occur in recess working portions such as small-diameter hole working and small-diameter recess R working than in the case where the shape is short.

Disclosure of Invention

Problems to be solved by the invention

In the technique described in patent document 2, it is attempted to suppress deterioration of a thin polarizer in a humidified environment and generation of cracks at the time of thermal shock by using a polarizing film using a resin film having a very low moisture permeability as a protective film in the thin polarizer. However, in recent years, a special-shaped polarizing film subjected to small-diameter hole machining or small-diameter recess machining is required to have durability by a more severe crack test capable of evaluating the presence or absence of cracks in a machined portion upon thermal shock. Therefore, in actual circumstances, there is room for further improvement in durability against cracks in the polarizing films reported so far.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polarizing film and a method for producing the same, which can achieve both suppression of a decrease in optical characteristics in a humidified environment and excellent crack durability which are particularly required for a special-shaped polarizing film subjected to small-diameter recess R processing and small-diameter hole processing, for example.

Further, it is an object of the present invention to provide an optical film in which at least 1 sheet of the polarizing film is laminated, and an image display device using the polarizing film and/or the optical film.

Means for solving the problems

The above problem can be solved by the following constitution. That is, the present invention relates to a polarizing film comprising a polarizer and a transparent protective film provided on at least one surface of the polarizer via an adhesive layer, wherein the transparent protective film is a cellulose-based resin film, the adhesive layer is formed of a cured product layer obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray, and the composition contains an SP value of 29.0 (MJ/m) when the total amount of the active energy ray-curable adhesive composition is 100 wt%³)^1/232.0 (MJ/m) of the above³)^1/2The active energy ray-curable compound (A) is 0.0 to 4.0 wt% and has an SP value of 18.0 (MJ/m)³)^1/2Above and less than 21.0 (MJ/m)³)^1/25.0 to 98.0 wt% of the active energy ray-curable compound (B) and 21.0 SP value (MJ/m)³)^1/2Above and 26.0 (MJ/m)³)^1/2The active energy ray-curable compound (C) is 5.0 to 98.0 wt%.

Preferably, in the polarizing film, the polarizer has a thickness of 3 μm or more and 15 μm or less.

Preferably, the polarizing film contains 20 to 80 wt% of the active energy ray-curable compound (B) based on 100 wt% of the total amount of the active energy ray-curable adhesive composition.

Preferably, in the polarizing film, the active energy ray-curable adhesive composition contains an acrylic oligomer (D) obtained by polymerizing a (meth) acrylic monomer.

Preferably, in the polarizing film, the active energy ray-curable adhesive composition represented by the following formula (1) has an acryloyl equivalent C_aeThe content of the organic acid is more than 140,

C_ae＝1/Σ(W_N/N_ae)(1)

in the above formula (1), W_NIs the mass fraction of the active energy ray-curable compound N in the composition, N_aeThe acryloyl equivalent weight of the active energy ray-curable compound N.

Preferably, in the polarizing film, the active energy ray-curable adhesive composition contains a radical polymerization initiator having a hydrogen abstraction effect.

In the polarizing film, the radical polymerization initiator is preferably a thioxanthone radical polymerization initiator.

Preferably, in the polarizing film, the active energy ray-curable adhesive composition contains an acrylic oligomer (D),

a compatible layer having a continuously changing composition is formed between the transparent protective film and the adhesive layer,

when the thickness of the compatible layer is P (μm), the total amount of the composition is 100% by weight, and the content of the acrylic oligomer (D) in this case is Q% by weight, the P × Q value is less than 10.

Preferably, the polarizing film includes a compound represented by the following general formula (1) on at least one of the surfaces to be bonded of the polarizer and the transparent protective film,

[ chemical formula 1]

(wherein X is a functional group containing a reactive group, R¹And R²Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group or a heterocyclic group),

the compound represented by the general formula (1) is interposed between the polarizer and the adhesive layer, and/or between the transparent protective film and the adhesive layer.

Preferably, in the polarizing film, the compound represented by the general formula (1) is a compound represented by the following general formula (1'),

[ chemical formula 2]

(wherein Y is an organic group, X, R)¹And R²The same as described above).

Preferably, the polarizing film includes a compound represented by the general formula (1) on the surface to be bonded to the polarizer.

In the polarizing film, the reactive group of the compound represented by the general formula (1) is preferably at least 1 reactive group selected from an α, β -unsaturated carbonyl group, a vinyl ether group, an epoxy group, an oxetanyl group, an amino group, an aldehyde group, a mercapto group, and a halogen group.

In addition, the present invention relates to a method for manufacturing a polarizing filmA method, comprising: a coating step of coating an active energy ray-curable adhesive composition on at least one surface of the polarizer and the transparent protective film; a bonding step of bonding the polarizer and the transparent protective film; and an adhesion step of irradiating the polarizer surface side or the transparent protective film surface side with an active energy ray to adhere the polarizer and the transparent protective film via an adhesive layer obtained by curing the active energy ray-curable adhesive composition, wherein the transparent protective film is a cellulose-based resin film, and the composition contains an SP value of 29.0 (MJ/m) when the total amount of the active energy ray-curable adhesive composition is 100 wt%³)^1/232.0 (MJ/m) of the above³)^1/2The active energy ray-curable compound (A) is 0.0 to 4.0 wt% and has an SP value of 18.0 (MJ/m)³)^1/2Above and less than 21.0 (MJ/m)³)^1/25.0 to 98.0 wt% of the active energy ray-curable compound (B) and 21.0 SP value (MJ/m)³)^1/2Above and 26.0 (MJ/m)³)^1/2The active energy ray-curable compound (C) is 5.0 to 98.0 wt%.

Preferably, the method for producing the polarizing film includes an easy-adhesion treatment step of adhering a compound represented by the following general formula (1) to at least one of the surfaces to be bonded of the polarizer and the transparent protective film,

[ chemical formula 3]

(wherein X is a functional group containing a reactive group, R¹And R²Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group, or a heterocyclic group).

Preferably, in the method for producing a polarizing film, the compound represented by the general formula (1) is a compound represented by the general formula (1'),

[ chemical formula 4]

(wherein Y is an organic group, X, R)¹And R²The same as described above).

In the method for producing a polarizing film, at least one surface of the polarizer and the transparent protective film, that is, a surface on the side to be bonded is preferably subjected to corona treatment, plasma treatment, excimer treatment, or flame treatment before the coating step.

Preferably, in the method for producing a polarizing film, the active energy ray includes visible light having a wavelength of 380 to 450 nm.

In the method for producing the polarizing film, the ratio of the cumulative illuminance of the active energy ray in the wavelength range of 380 to 440nm to the cumulative illuminance in the wavelength range of 250 to 370nm is preferably 100:0 to 100: 50.

The present invention also relates to an optical film obtained by laminating at least 1 polarizing film described above, and an image display device using the polarizing film described above and/or the optical film described above.

ADVANTAGEOUS EFFECTS OF INVENTION

As described above, in addition to the special-shaped polarizing film subjected to the small-diameter recess R processing and the small-diameter hole processing, it is difficult to achieve both suppression of optical property degradation in a humidified environment and excellent crack durability in a general polarizing film having a short shape for various reasons. The present inventors have conducted intensive studies to achieve the above-mentioned balance, and as a result, have found that the above-mentioned object can be achieved by first developing (i) an active energy ray-curable adhesive composition capable of forming an adhesive layer having improved adhesion between a polarizer and a transparent protective film and improved optical durability, and then selecting (ii) an optimum transparent protective film to combine with (i).

First, (i) an active energy ray-curable adhesive composition will be described. In order to form an adhesive layer having improved adhesion between a polarizer and a transparent protective film and improved optical durability, in the present invention, an active energy ray-curable adhesive composition contains at least an active energy rayA radiation-curable compound (A), an active energy ray-curable compound (B), and an active energy ray-curable compound (C). The SP value of the active energy ray-curable compound (A) was 29.0 (MJ/m)³)^1/232.0 (MJ/m) of the above³)^1/2Hereinafter, the composition ratio is 0.0 to 4.0 wt% based on 100 wt% of the total composition. The active energy ray-curable compound (a) has a high SP value, and thus contributes to, for example, improvement in adhesion between a PVA-based polarizer (for example, SP value 32.8) and a saponified triacetylcellulose (for example, SP value 32.7) as a transparent protective film and an adhesive layer. On the other hand, when the content of the active energy ray-curable compound (a) in the active energy ray-curable adhesive composition is large, the optical durability is deteriorated. Therefore, the upper limit of the active energy ray-curable compound (a) is preferably 4.0% by weight, more preferably 2.0% by weight, even more preferably 1.5% by weight, even more preferably 1.0% by weight, and particularly preferably no active energy ray-curable compound (a) is contained, when the total amount of the composition is 100% by weight.

The SP value of the active energy ray-curable compound (B) was 18.0 (MJ/m)³)^1/2Above and less than 21.0 (MJ/m)³)^1/2The composition ratio is 5.0 to 98.0 wt%. The active energy ray-curable compound (B) has a low SP value, and the SP value greatly differs from water (SP value 47.9), which contributes to an improvement in the water resistance of the adhesive layer. The composition ratio is preferably 20 to 80% by weight, more preferably 25 to 70% by weight, based on 100% by weight of the total composition.

The SP value of the active energy ray-curable compound (C) was 21.0 (MJ/m)³)^1/2Above and 26.0 (MJ/m)³)^1/2The composition ratio is 5.0 to 98.0 wt% as follows. The SP value of the active energy ray-curable compound (C) is close to, for example, the SP value (for example, 23.3) of unsaponifiable triacetylcellulose as a transparent protective film and the SP value (for example, 22.2) of an acrylic film, and therefore, contributes to improvement of adhesion to these transparent protective films. The composition ratio is preferably 20 to 80% by weight, more preferably 25 to 70% by weight, based on 100% by weight of the total composition.

In the present invention, the specific (ii) transparent protective film is bonded to the polarizer by the above-described (i) active energy ray-curable adhesive composition.

As the (ii) transparent protective film, a cellulose-based resin film was used. The cellulose-based resin film has a small dimensional change and a low linear expansion coefficient when thermally impacted. On the other hand, the moisture permeability is high. Therefore, in order to achieve both suppression of the decrease in optical characteristics of the polarizing film in a humidified environment and excellent crack durability, both positive and negative effects are present in the cellulose-based resin film, but the negative effects of the cellulose-based resin film can be compensated by bonding the polarizer to the adhesive layer formed of the cured product layer of the active energy ray-curable adhesive composition (i) described above, and the above-described problems can be achieved.

In particular, in the present invention, it is preferable to bond a specific (ii) transparent protective film and a specific (iii) thin polarizer having a thickness of 3 μm or more and 15 μm or less to each other via an adhesive layer formed of a cured layer of a specific (i) active energy ray-curable adhesive composition to form a polarizing film, because the reduction in optical properties of the polarizing film in a humidified environment and the excellent crack durability can be simultaneously suppressed at a higher level.

Drawings

Fig. 1 is a schematic view of a polarizing film with an adhesive layer on which a crack evaluation test was performed.

Detailed Description

The polarizing film of the present invention is configured by bonding a specific transparent protective film and a polarizer via an adhesive layer formed of a cured product layer of a specific active energy ray-curable adhesive composition.

< active energy ray-curable adhesive composition >

The active energy ray-curable adhesive composition contains active energy ray-curable compounds (a), (B), and (C) as curable components. Specifically, the SP value of 29.0 (MJ/m) was contained, assuming that the total amount of the composition was 100 wt%³)^1/232.0 (MJ/m) of the above³)^1/2The following are provided0.0 to 4.0 wt% of the active energy ray-curable compound (A) and an SP value of 18.0 (MJ/m)³)^1/2Above and less than 21.0 (MJ/m)³)^1/25.0 to 98.0 wt% of the active energy ray-curable compound (B) and 21.0 SP value (MJ/m)³)^1/2Above and 26.0 (MJ/m)³)^1/2The active energy ray-curable compound (C) is 5.0 to 98.0 wt%. In the present invention, the "total amount of the composition" means the total amount including the active energy ray-curable compound, and various initiators and additives.

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

(method of calculating solubility parameter (SP value))

In the present invention, the solubility parameters (SP values) of the active energy ray-curable compound, polarizer, various transparent protective films, and the like are calculated by Fedors' calculation method [ see "polymer engineering and science (PolymerEng. & Sci.)", volume 14, No.2 (1974), pages 148 to 154 ], as follows:

[ mathematical formula 1]

(wherein. DELTA.ei is the evaporation energy at 25 ℃ attributed to an atom or group, and. DELTA.vi is the molar volume at 25 ℃).

Δ ei and Δ vi in the above numerical formulae represent certain numerical values given to i atoms and groups in the main molecule. In addition, the numerical values of Δ e and Δ v assigned to atoms or groups are shown in table 1 below.

[ Table 1]

Atom or group	Δe(J/mol)	Δv(cm3/mol)
			CH3	4086	33.5
C	1465	-19.2
			Phenyl radical	31940	71.4
Phenylene radical	31940	52.4
			COOH	27628	28.5
CONH2	41861	17.5
			NH2	12558	19.2
-N＝	11721	5.0
			CN	25535	24.0
NO2(fatty acid)	29302	24.0
			NO3(aromatic)	15363	32.0
O	3349	3.8
			OH	29805	10.0
S	14149	12.0
			F	4186	18.0
Cl	11553	24.0
			Br	15488	30.0

The active energy ray-curable compound (A) is not particularly limited as long as it has a radical-polymerizable group such as a (meth) acrylate group and has an SP value of 29.0: (MJ/m³)^1/232.0 (MJ/m) of the above³)^1/2The following compounds may be used without limitation. Specific examples of the active energy ray-curable compound (a) include: hydroxyethyl acrylamide (SP value 29.5), N-methylolacrylamide (SP value 31.5), and the like. In the present invention, the (meth) acrylate group means an acrylate group and/or a methacrylate group.

The active energy ray-curable compound (B) is not particularly limited as long as it has a radical-polymerizable group such as a (meth) acrylate group and has an SP value of 18.0 (MJ/m)³)^1/2Above and less than 21.0 (MJ/m)³)^1/2The compound (4) can be used without limitation. Specific examples of the active energy ray-curable compound (B) include: tripropylene glycol diacrylate (SP value 19.0), 1, 9-nonanediol diacrylate (SP value 19.2), tricyclodecane dimethanol diacrylate (SP value 20.3), cyclotrimethylolpropane formal acrylate (SP value 19.1), and ditrimethylolAlkylene glycol diacrylate (SP value 19.4) and EO-modified diglycerol tetraacrylate (SP value 20.9). As the active energy ray-curable compound (B), commercially available products can be suitably used, and examples thereof include: ARONIX M-220 (manufactured by Toyo Synthesis Co., Ltd., SP value 19.0), LIGHTACRYLATE 1,9ND-A (manufactured by Kyowa Kagaku K.K., SP value 19.2), LIGHTACRYLATE DGE-4A (manufactured by Kyowa Kagaku K.K., SP value 20.9), LIGHTACRYLATE DCP-A (manufactured by Kyowa Kagaku K.K., SP value 20.3), SR-531 (manufactured by SARTOMER K.K., SP value 19.1), CD-536 (manufactured by SARTOMER K.K., SP value 19.4), and the like.

The active energy ray-curable compound (C) is not particularly limited as long as it has a radical-polymerizable group such as a (meth) acrylate group and has an SP value of 21.0 (MJ/m)³)^1/2Above and 26.0 (MJ/m)³)^1/2The following compounds may be used without limitation. Specific examples of the active energy ray-curable compound (C) include: acryloyl morpholine (SP value 22.9), N-methoxy methyl propaneEnamides (SP value 22.9), N-ethoxymethacrylamides (SP value 22.3), and the like. As the active energy ray-curable compound (C), commercially available products can be suitably used, and examples thereof include: ACMO (manufactured by Shikino corporation, SP value 22.9), Wasmer 2MA (manufactured by Chimaphila corporation, SP value 22.9), Wasmer EMA (manufactured by Chimaphila corporation, SP value 22.3), and Wasmer 3MA (manufactured by Chimaphila corporation, SP value 22.4).

In the present invention, the acryl equivalent C of the active energy ray-curable adhesive composition represented by the following formula (1)_aeWhen the content is 140 or more, the curing shrinkage of the active energy ray-curable adhesive composition during curing can be suppressed. This is preferable because the adhesiveness to an adherend, particularly to a polarizer, is improved.

C_ae＝1/Σ(W_N/N_ae)(1)

In the above formula (1), W_NIs the mass fraction of the active energy ray-curable compound N in the composition, N_aeThe acryloyl equivalent weight of the active energy ray-curable compound N. In the present invention, the reason why the adhesive strength of the adhesive layer obtained when the acryl equivalent of the active energy ray-curable adhesive composition is not less than a predetermined value is improved is presumed as follows.

The higher the acryloyl equivalent weight of the active energy ray-curable adhesive composition, the more effective it is to suppress volume shrinkage that occurs due to formation of covalent bonds when the composition is cured by irradiation with active energy rays. This can alleviate the stress that remains at the interface between the adhesive layer and the adherend, and as a result, the adhesive strength of the adhesive layer can be improved.

Acryl equivalent C_aeMore preferably 155 or more, and still more preferably 165 or more. In the present invention, the acryloyl equivalent weight is defined as follows.

(acryloyl equivalent) (molecular weight of acrylic monomer)/(number of (meth) acryloyl groups contained in acrylic monomer 1 molecule)

The active energy ray-curable adhesive composition may contain an acrylic oligomer (D) obtained by polymerizing a (meth) acrylic monomer, in addition to the active energy ray-curable compounds (a), (B), and (C) as the curable components. By containing the component (D) in the active energy ray-curable adhesive composition, the volume shrinkage of the composition when irradiated with an active energy ray and cured can be reduced, and the interfacial stress between the adhesive layer and an adherend such as a polarizer and a transparent protective film can be reduced. As a result, the adhesive layer can be prevented from being deteriorated in adhesiveness to the adherend. In order to sufficiently suppress the curing shrinkage of the cured product layer (adhesive layer), the acrylic oligomer (D) is preferably contained in the adhesive composition in an amount of 3.0 wt% or more, more preferably 5.0 wt% or more. 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 an active energy ray may be rapidly decreased, and curing may be defective. Therefore, the content of the acrylic oligomer (D) in the adhesive composition is preferably 25% by weight or less, and more preferably 15% by weight or less.

In view of workability and uniformity in application, the active energy ray-curable adhesive composition preferably has a low viscosity, and therefore the acrylic oligomer (D) obtained by polymerizing the (meth) acrylic monomer is also preferably low in viscosity. The weight average molecular weight (Mw) of the low-viscosity acrylic oligomer capable of preventing curing shrinkage of the adhesive layer is preferably 15000 or less, more preferably 10000 or less, and particularly preferably 5000 or less. On the other hand, in order to sufficiently suppress curing shrinkage of the cured product layer (adhesive layer), the weight average molecular weight (Mw) of the acrylic oligomer (D) is preferably 500 or more, more preferably 1000 or more, and particularly preferably 1500 or more. Specific examples of the (meth) acrylic monomer constituting the acrylic oligomer (D) include: (meth) acrylic acid (C1-20) alkyl esters such as 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, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, and n-octadecyl (meth) acrylate, And for example: cycloalkyl (meth) acrylates (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), (aralkyl (meth) acrylates (e.g., benzyl (meth) acrylate, etc.), polycyclic (meth) acrylates (e.g., 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norborn-2-ylmethyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, etc.), hydroxyl-containing (meth) acrylates (e.g., hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 3-dihydroxypropylmethylbutyl (meth) acrylate, etc.), alkoxy-or phenoxy-containing (meth) acrylates ((2-methoxyethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, etc.), 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and the like, epoxy group-containing (meth) acrylates (e.g., glycidyl (meth) acrylate, and the like), halogen-containing (meth) acrylates (e.g., 2,2, 2-trifluoroethyl (meth) acrylate, 2,2, 2-trifluoroethyl ethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.), alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate, etc.), and the like. These (meth) acrylates may be used singly or in combination of 2 or more. Specific examples of the acrylic oligomer (D) include "ARUFON" manufactured by Toyo Synthesis Co., Ltd, "ACTFLOW" manufactured by Soken chemical Co., Ltd, "JONCRYL" manufactured by BASF Japan Ltd.

The active energy ray-curable adhesive composition preferably contains a radical polymerization initiator (E) having a hydrogen abstraction action. According to this configuration, the adhesiveness of the adhesive layer of the polarizing film is significantly improved even immediately after the polarizing film is taken out from a high-humidity environment or from water (in a non-dried state). The reason is not clear, but is considered to be the following reason. When the radical polymerization initiator (E) having a hydrogen abstraction action is present in the active energy ray-curable adhesive composition, the active energy ray-curable compound is polymerized to form a base polymer constituting the adhesive layer, and hydrogen is abstracted from, for example, methylene groups of the active energy ray-curable compound to generate radicals. Then, methylene groups or the like which generate radicals react with hydroxyl groups of a polarizer such as PVA to form covalent bonds between the adhesive layer and the polarizer. As a result, it is presumed that the adhesiveness of the adhesive layer of the polarizing film is significantly improved particularly in a non-dried state.

In the present invention, examples of the radical polymerization initiator (E) having a hydrogen abstraction action include: thioxanthone radical polymerization initiators, benzophenone radical polymerization initiators, and the like. Examples of the thioxanthone-based radical polymerization initiator include compounds represented by the following general formula (2).

[ chemical formula 5]

(in the formula, R³And R⁴represents-H, -CH₂CH₃-iPr or Cl, R³And R⁴Optionally the same or different)

When the compound represented by the general formula (2) is used, the adhesiveness is superior to that when a photopolymerization initiator having high sensitivity to light of 380nm or more is used alone. The photopolymerization initiator having high sensitivity to light of 380nm or more will be described later. Among the compounds represented by the general formula (2), R is particularly preferable³And R⁴is-CH₂CH₃Diethyl thioxanthone (ll).

The photopolymerization initiator of the general formula (2) can initiate polymerization by transmitting light of a long wavelength of the transparent protective film having UV absorption ability, and thus can cure the adhesive even through the UV absorption film. Specifically, even when a transparent protective film having UV absorbing ability is laminated on both surfaces, such as cellulose triacetate-polarizer-cellulose triacetate, the adhesive composition can be cured when the photopolymerization initiator of the general formula (2) is contained.

The composition ratio of the radical polymerization initiator (E) having a hydrogen abstraction action in the composition, particularly the composition ratio of the compound represented by the general formula (2), is preferably 0.1 to 10% by weight, more preferably 0.2 to 5% by weight, based on 100% by weight of the total composition.

Further, it is preferable to add a polymerization initiation aid as needed. Examples of the polymerization initiation aid include: triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, etc., with ethyl 4-dimethylaminobenzoate being particularly preferred. When the polymerization initiator aid is used, the amount of the polymerization initiator aid added is usually 0 to 5% by weight, preferably 0 to 4% by weight, and most preferably 0 to 3% by weight, based on 100% by weight of the total composition.

Further, a known photopolymerization initiator may be used in combination as necessary. Since the transparent protective film having UV absorption ability does not transmit light of 380nm or less, it is preferable to use a photopolymerization initiator having high sensitivity to light of 380nm or more as the photopolymerization initiator. Specifically, there may be mentioned: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholino) phenyl ] -1-butanone, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, bis (Η 5-2, 4-cyclopentadien-1-yl) bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium, and the like.

In particular, the photopolymerization initiator preferably further contains a compound represented by the following general formula (3) in addition to the photopolymerization initiator of the general formula (2),

[ chemical formula 6]

(in the formula, R⁵、R⁶And R⁷represents-H, -CH₃、-CH₂CH₃-iPr or Cl, R⁵、R⁶And R⁷Optionally the same or different). By using the photopolymerization initiators of the general formulae (2) and (3) in combination, the reaction efficiency can be improved by the photoreaction, and particularly the adhesiveness of the adhesive layer can be improved.

The active energy ray-curable adhesive composition preferably further contains a radical polymerization initiator (E) having a hydrogen abstraction action and an active energy ray-curable compound having an active methylene group. With this configuration, the adhesiveness of the adhesive layer included in the polarizing film is further improved.

The active energy ray-curable compound having an active methylene group is a compound having an active methylene group and an active double bond group such as a (meth) acryloyl group at a terminal or in a molecule. Examples of the active methylene group include: acetoacetyl, alkoxymalonyl, cyanoacetyl, or the like. Specific examples of the active energy ray-curable compound having an active methylene group include: acetoacetoxyethyl alkyl (meth) acrylates such as 2-acetoacetoxyethyl (meth) acrylate, 2-acetoacetoxyethyl propyl (meth) acrylate, and 2-acetoacetoxyethyl-1-methylethyl (meth) acrylate; 2-ethoxymalonyloxyethyl (meth) acrylate, 2-cyanoacetoxyethyl (meth) acrylate, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetyloxybutyl) acrylamide, N- (4-acetoacetoxyethylmethylbenzyl) acrylamide, N- (2-acetoacetylaminoethyl) acrylamide and the like. The radical polymerizable compound having an active methylene group is preferably acetoacetoxyethyl (meth) acrylate. The SP value of the active energy ray-curable compound having an active methylene group is not particularly limited, and any value can be used.

< photoacid generators >

The active energy ray-curable resin composition may contain a photoacid generator. When the photoacid generator is contained in the active energy ray-curable resin composition, the water resistance and durability of the adhesive layer can be greatly improved. The photoacid generator can be represented by the following general formula (4).

General formula (4)

[ chemical formula 7]

L⁺·X^-.

(wherein, L⁺Means of being arbitraryA cation. In addition, X^-Is selected from PF6₆ ^-、SbF₆ ^-、AsF₆ ^-、SbCl₆ ^-、BiCl₅ ^-、SnCl₆ ^-、ClO₄ ^-Dithiocarbamate anion, SCN^-The counter anion of (1). )

Next, for the counter anion X in the general formula (4)^-The description is given.

In principle on the counter anion X in the general formula (4)^-The anion is not particularly limited, but a non-nucleophilic anion is preferable. When the counter anion X is a non-nucleophilic anion, the photoacid generator represented by the general formula (4) itself and a composition using the same can be improved in stability with time because a nucleophilic reaction of a cation coexisting in a molecule and various materials used in combination is not easily caused. The term "non-nucleophilic anion" as used herein refers to an anion having a low ability to cause nucleophilic reaction. Examples of such anions include: PF (particle Filter)₆ ^-、SbF₆ ^-、AsF₆ ^-、SbCl₆ ^-、BiCl₅ ^-、SnCl₆ ^-、ClO₄ ^-Dithiocarbamate anion, SCN^-And the like.

Specifically, preferable specific examples of the photoacid generator of the present invention include: "CYRACURE UVI-6992", "CYRACURE UVI-6974" (manufactured by Dow chemical Japan Limited, supra), "Adekaoptomer SP 150", "Adekaoptomer SP 152", "Adekaoptomer SP 170", "Adekaoptomer SP 172" (manufactured by Kokusho ADEKA), "IRGACURE 250" (manufactured by Ciba specialty Chemicals Inc.), "CI-5102", "CI-2855" (manufactured by Nippon Soda Co., Ltd), "San-Aid SI-60L", "San-Aid SI-80L", "San-Aid SI-100L", "San-Aid SI-110L", "San-Aid SI-180L" (manufactured by Sanxin Co., Ltd), "CPI-100P", "WPI-100A" (manufactured by Sanp-06I-113, WPI-6974) "," WPI-04I-116 "(manufactured by Sanxin Co., Ltd.," WPI-100A "," WPI-100L "(manufactured by Sanp-100L)", "WPI-113, and" WPI-04I-113 "(manufactured by Wp-116 "WPI-054", "WPI-055", "WPAG-281", "WPAG-567", and "WPAG-596" (manufactured by Wako pure chemical industries, Ltd.).

The content of the photoacid generator is 10 wt% or less, preferably 0.01 to 10 wt%, more preferably 0.05 to 5 wt%, and particularly preferably 0.1 to 3 wt% with respect to the total amount of the composition.

< Compound containing any of alkoxy group and epoxy group >

The active energy ray-curable adhesive composition may be used in combination with a compound containing a photoacid generator and any of an alkoxy group and an epoxy group.

(Compound having epoxy group and Polymer)

When a compound having 1 or more epoxy groups in a molecule or a polymer (epoxy resin) having 2 or more epoxy groups in a molecule is used, a compound having two or more functional groups reactive with epoxy groups in a molecule may be used in combination. Among them, examples of the functional group reactive with an epoxy group include: carboxyl, phenolic hydroxyl, mercapto, primary or secondary aromatic amino, and the like. In view of three-dimensional curability, it is particularly preferable to have 2 or more of these functional groups in one molecule.

Examples of the polymer having 1 or more epoxy groups in the molecule include epoxy resins including bisphenol a type epoxy resins derived from bisphenol a and epichlorohydrin, bisphenol F type epoxy resins derived from bisphenol F and epichlorohydrin, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol a novolac type epoxy resins, bisphenol F novolac type epoxy resins, alicyclic epoxy resins, diphenyl ether type epoxy resins, hydroquinone type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, fluorene type epoxy resins, 3-functional epoxy resins, polyfunctional epoxy resins such as 4-functional epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, aliphatic chain epoxy resins, and the like, these epoxy resins may be halogenated or hydrogenated. Examples of commercially available epoxy resin products include: JER code 828, 1001, 801N, 806, 807, 152, 604, 630, 871, YX8000, YX8034, YX4000, EPICLON830, EXA835LV, HP4032D, HP820, EP4100 series manufactured by ADEKA, EP4000 series, EPU series, Daicel Chemical Industries, CELLOXIDE series (2021, 2021P, 2083, 2085, 3000, etc.) manufactured by Ltd, Epolead series, EHPE series, YD series, YDF series, YDCN series, YDB series, phenoxy resins (polyhydroxy polyethers synthesized from bisphenols and epichlorohydrin and having Epoxy groups at both ends; YP series, etc.), Denase Chemtecol series manufactured by Nagage, Inc., manufactured by Coppon Epoxy Corporation, etc., but are not limited thereto. These epoxy resins may be used in combination of 2 or more.

(Compound having alkoxy group and Polymer)

The compound having an alkoxy group in the molecule is not particularly limited as long as it has 1 or more alkoxy groups in the molecule, and known compounds can be used. Such compounds are typically exemplified by melamine compounds, amino resins, silane coupling agents, and the like.

The amount of the compound containing either an alkoxy group or an epoxy group is usually 30% by weight or less based on the total amount of the composition, and if the content of the compound in the composition is too large, the adhesiveness is lowered and the impact resistance in the drop weight test may be deteriorated. The content of the compound in the composition is more preferably 20% by weight or less. On the other hand, from the viewpoint of water resistance, the compound is preferably contained in the composition in an amount of 2% by weight or more, more preferably 5% by weight or more.

< silane coupling agent >

The silane coupling agent is not particularly limited and an organosilicon compound having an Si — O bond can be used, and specific examples thereof include an active energy ray-curable organosilicon compound and an inactive energy ray-curable organosilicon compound. It is particularly preferable that the organic group of the organosilicon compound has 3 or more carbon atoms. Examples of the active energy ray-curable compound include: vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane and the like.

3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane are preferred.

Specific examples of the non-active energy ray-curable compound include compounds having an amino group. Specific examples of the compound having an amino group include: gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltriisopropoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma- (2-aminoethyl) aminopropyltrimethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldimethoxysilane, gamma- (2-aminoethyl) aminopropyltriethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldiethoxysilane, gamma- (2-aminoethyl) aminopropyltriisopropoxysilane, gamma- (2- (2-aminoethyl) aminopropyltrimethoxysilane, gamma- (6-aminohexyl) aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-2-aminopropyltrimethoxysilane, gamma-methyldiethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-methyldimethoxysilane, gamma-aminopropyltrimethoxysilane, amino-containing silanes such as 3- (N-ethylamino) -2-methylpropyltrimethoxysilane, γ -ureidopropyltrimethoxysilane, γ -ureidopropyltriethoxysilane, N-phenyl- γ -aminopropyltrimethoxysilane, N-benzyl- γ -aminopropyltrimethoxysilane, N-vinylbenzyl- γ -aminopropyltriethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl) aminomethyltrimethoxysilane and N, N' -bis [3- (trimethoxysilyl) propyl ] ethylenediamine; ketimine-type silanes such as N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine.

Only 1 kind of the compound having an amino group may be used, or a plurality of kinds may be used in combination. Of these, γ -aminopropyltrimethoxysilane, γ - (2-aminoethyl) aminopropylmethyldimethoxysilane, γ - (2-aminoethyl) aminopropyltriethoxysilane, γ - (2-aminoethyl) aminopropylmethyldiethoxysilane and N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine are preferable for ensuring good adhesion.

Specific examples of the non-active energy ray-curable compound other than the above include: 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, imidazolesilane and the like.

The amount of the silane coupling agent is preferably in the range of 0.01 to 20 wt%, more preferably 0.05 to 15 wt%, and still more preferably 0.1 to 10 wt% based on the total amount of the curable resin composition. This is because the storage stability of the curable resin composition is deteriorated when the blending amount exceeds 20 wt%, and the effect of the adhesion water resistance cannot be sufficiently exhibited when the blending amount is less than 0.1 wt%.

< Compound having vinyl Ether group >

When the active energy ray-curable adhesive composition used in the present invention contains a compound having a vinyl ether group, the adhesion between the polarizer and the adhesive layer is preferably improved in water resistance. The reason for obtaining this effect is not clear, but it is presumed that one of the reasons is that the adhesion between the polarizer and the adhesive layer is improved by the interaction between the vinyl ether group of the compound and the polarizer. In order to further improve the water resistance of adhesion between the polarizer and the adhesive layer, the compound is preferably an active energy ray-curable compound having a vinyl ether group. The content of the compound is preferably 0.1 to 19% by weight based on the total amount of the curable resin composition.

Additives other than the above

In addition, various additives may be added to the curable resin composition used in the present invention as other optional components within a range not impairing the object and effects of the present invention. Examples of such additives include: polymers or oligomers such as epoxy resins, polyamides, polyamideimides, polyurethanes, polybutadienes, polychloroprenes, polyethers, polyesters, styrene-butadiene block copolymers, petroleum resins, xylene resins, ketone resins, cellulose resins, fluorine-based oligomers, silicone-based oligomers, and polythioether-based oligomers; polymerization inhibitors such as phenothiazine and 2, 6-di-tert-butyl-4-methylphenol; a polymerization initiation aid; leveling agent; a wettability modifier; a surfactant; a plasticizer; an ultraviolet absorber; an inorganic filler; a pigment; dyes, and the like.

The additive is usually 0 to 10% by weight, preferably 0 to 5% by weight, and most preferably 0 to 3% by weight, based on the total amount of the curable resin composition.

< adhesive layer >

The thickness of the adhesive layer formed by the active energy ray-curable adhesive composition is preferably 0.01 to 3.0 μm. If the thickness of the adhesive layer is too thin, the cohesive force of the adhesive layer is insufficient, and the peel force is reduced, which is not preferable. When the thickness of the adhesive layer is too large, peeling is likely to occur when stress is applied to the cross section of the polarizing film, and peeling failure due to impact occurs, which is not preferable. The thickness of the adhesive layer is more preferably 0.1 to 2.5 μm, and most preferably 0.5 to 1.5 μm.

< transparent protective film >

In the present invention, a cellulose-based resin film is used as the transparent protective film. The cellulose-based resin film refers to a film containing a cellulose ester such as cellulose acetate as a main component, and is produced by, for example, melt extrusion molding of a cellulose ester alone or, if necessary, a cellulose ester and other polymer components as raw materials. The term "main component" means that the resin film contains 50% by weight or more of cellulose ester, and particularly, from the viewpoint of improving the crack durability of the polarizing film, a cellulose-based resin film containing 50% by weight or more of cellulose ester is preferably used as the transparent protective film, and a cellulose-based resin film containing 70% by weight or more of cellulose ester is particularly preferably used. As the cellulose ester, it is particularly preferable to react cellulose as a natural polymer with acetic anhydride to replace the hydroxyl group (OH-) contained in the cellulose molecule with acetyl group (CH)₃The acetyl cellulose obtained by CO-) (acetylation) is particularly preferably TAC (triacetylcellulose) obtained by acetylating all the hydroxyl groups.

In the present invention, a cellulose resin film having a retardation may be used as the transparent protective film. In this case, the transparent protective film is preferably used as a retardation film because the polarizing film can be thinned. The cellulose resin film having a retardation is also produced by melt extrusion molding of cellulose ester alone or, if necessary, with other polymer components as raw materials. The cellulose ester can control the retardation value of the retardation film obtained by changing the type of the substituent of the lower fatty acid and the substitution degree of the lower fatty acid. In addition, a retardation enhancer or a retardation controller may be contained for controlling the retardation. The cellulose ester can be produced by any suitable method, for example, the method described in Japanese patent application laid-open No. 2001-188128. In addition, there are a large number of commercially available cellulose esters, and these are advantageous from the viewpoint of availability and cost. Examples of commercially available cellulose esters include trade names "UV-50", "UV-80", "SH-80", "TD-80U", "TD-TAC", "UZ-TAC" manufactured by Fuji film Co., Ltd and "KC series" manufactured by Konika K.K.

When the cellulose ester contains an acetyl group as a substituent of the lower fatty acid, the degree of substitution with the acetyl group is preferably 3 or less, more preferably 0.5 to 3, and particularly preferably 1 to 3. When the cellulose ester contains propionyl as a substituent of the lower fatty acid, the substitution degree of propionyl is preferably 3 or less, more preferably 0.5 to 3, and particularly preferably 1 to 3. In the case where the cellulose ester is a mixed fatty acid ester in which a part of the hydroxyl groups of the cellulose is substituted with an acetyl group and the other part is substituted with a propionyl group, the total of the degree of substitution with the acetyl group and the degree of substitution with the propionyl group is preferably 1 to 3, and more preferably 2 to 3. In this case, the degree of substitution with acetyl is preferably 0.5 to 2.5, and the degree of substitution with propionyl is preferably 0.3 to 1.5.

The substitution degree of an acetyl group (or a substitution degree of a propionyl group) means the number of hydroxyl groups connected to the carbon at the 2,3, and 6 positions in the cellulose skeleton substituted with an acetyl group (or a propionyl group). Any of the carbons at the 2,3, and 6 positions in the cellulose skeleton may be biased to an acetyl group (or propionyl group), or may be present on average. The degree of substitution with an acetyl group can be determined by ASTM-D817-91 (test method such as cellulose acetate). The substitution degree of propionyl group can be determined by ASTM-D817-96 (test method such as cellulose acetate).

The cellulose ester preferably has a weight average molecular weight (Mw) of 30000 to 500000, more preferably 50000 to 400000, and most preferably 80000 to 300000, as measured by a Gel Permeation Chromatography (GPC) method using a tetrahydrofuran solvent. When the weight average molecular weight is in the above range, the composition can be excellent in mechanical strength, solubility, moldability and casting workability.

The cellulose ester preferably has a molecular weight distribution (weight average molecular weight Mw/number average molecular weight Mn) of 1.5 to 5.5, more preferably 2 to 5.

It is preferable that the cellulose-based resin film having a phase difference satisfies the relationship of nx > ny > nz. The cellulose resin film having retardation is controlled to have an in-plane retardation of 40 to 300nm and a thickness direction retardation of 80 to 320 nm. Further, the in-plane phase is preferably 40 to 100nm, the thickness direction retardation is preferably 100 to 320nm, and the Nz coefficient is preferably 1.8 to 4.5. The Nz coefficient is typically about 3.5 to 4.5. The cellulose resin film having such a retardation can improve the viewing angle characteristics in the oblique viewing direction. In particular, the liquid crystal display device is suitable for IPS mode and VA mode liquid crystal display devices. The Nz coefficient is represented by Nz ═ (nx-Nz)/(nx-ny) (nx, ny, Nz are defined similarly to the in-plane retardation and the thickness direction retardation).

Examples of the cellulose-based resin film having a retardation include biaxial retardation films (e.g., "WVBZ 4a 6", "WVBZ 4E 4" manufactured by fuji film co., and "KC 4 DR-1" manufactured by konika corporation) satisfying a refractive index relationship of nx > ny > nz. The control of these retardation can be achieved by uniaxially stretching or biaxially stretching a cellulose ester-containing polymer film in the machine direction or the transverse direction.

The cellulose resin film having a retardation may be, for example, a cellulose resin film having various wave plates or a cellulose resin film having a suitable retardation depending on the purpose of use, for example, for the purpose of utilizing coloring of birefringence of a liquid crystal layer, compensation of viewing angle, or the like, or a cellulose resin film having a retardation controlled by laminating 2 or more kinds of cellulose resin films having a retardation so as to control optical characteristics such as a retardation.

The transparent protective film may contain 1 or more kinds of any appropriate additives. Examples of additives include: ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the additive in the transparent protective film is preferably 0 to 50 wt%, more preferably 1 to 50 wt%, further preferably 2 to 40 wt%, and particularly preferably 3 to 30 wt%. When the amount of the additive in the transparent protective film exceeds the above range, there is a fear that high transparency of the transparent protective film cannot be sufficiently exhibited, and the like.

The polarizing film of the present invention may have a transparent protective film on only one surface of the polarizer with an adhesive layer interposed therebetween, or may have a transparent protective film on both surfaces of the polarizer with an adhesive layer interposed therebetween. In the former case, a cellulose-based resin film is used as the transparent protective film. In the latter case, on the other hand, it is necessary to laminate a cellulose-based resin film as a transparent protective film on one surface of the polarizer via an adhesive layer, or to laminate a cellulose-based resin film as a transparent protective film on the other surface, or to laminate a resin film other than the cellulose-based resin film as a transparent protective film.

As the transparent protective film that can be used in addition to the cellulose-based resin film, one having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferable. Examples of the polymer forming the transparent protective film include: polyester polymers such AS polyethylene terephthalate and polyethylene naphthalate, acrylic polymers such AS polymethyl methacrylate, styrene polymers such AS polystyrene and acrylonitrile-styrene copolymer (AS resin), and polycarbonate polymers. Further, polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, polyolefin polymer such as ethylene-propylene copolymer, vinyl chloride polymer, polyamide polymer such as nylon and aromatic polyamide, imide polymer, sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, polyaryl ester polymer, polyacetal polymer, epoxy polymer, or a mixture of the above polymers.

Further, as the transparent protective film that can be used in addition to the cellulose-based resin film, there can be mentioned a polymer film described in Japanese patent laid-open No. 2001-343529 (WO01/37007), for example, (A) a resin composition containing a thermoplastic resin having a substituted and/or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitrile group in the side chain. Specifically, a film of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer is exemplified. As the film, a film formed from a mixed extrusion of a resin composition or the like can be used. These films have a small phase difference and a small photoelastic coefficient, and therefore can eliminate problems such as unevenness due to strain of the polarizing film, and have a small moisture permeability, and therefore have excellent humidification durability.

The thickness of the transparent protective film can be suitably determined, and is preferably 5 to 100 μm in general from the viewpoints of strength, handleability such as handleability, thin layer property, and the like. Particularly preferably 10 to 60 μm, and more preferably 13 to 40 μm.

< polarizer >

In the present invention, from the viewpoint of improving crack durability, it is preferable to use a thin polarizer having a thickness of 3 μm or more and 15 μm or less as the polarizer. In particular, from the viewpoint of suppressing the occurrence of the through crack of the polarizer, it is preferably 12 μm or less, more preferably 10 μm or less, and particularly preferably 8 μm or less. Such a thin polarizer has excellent durability against thermal shock because of small thickness unevenness, excellent visibility, and small dimensional change.

As the polarizer, a polarizer using a polyvinyl alcohol resin can be used. Examples of the polarizer include films obtained by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene-vinyl acetate copolymer partially saponified films, and polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride desalted products, and the like. Among these, a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine is preferable.

A polarizer obtained by uniaxially stretching a polyvinyl alcohol film dyed with iodine can be produced, for example, as follows: the polyvinyl alcohol is dyed by immersing in an aqueous iodine solution and stretched to 3 to 7 times the original length. If necessary, the substrate may be immersed in an aqueous solution of potassium iodide or the like optionally containing boric acid, zinc sulfate, zinc chloride or the like. If necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol film with water, not only stains and an anti-blocking agent on the surface of the polyvinyl alcohol film can be washed, but also unevenness such as uneven dyeing can be prevented by swelling the polyvinyl alcohol film. The stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed after stretching with iodine. Stretching may also be carried out in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

In view of tensile stability and humidification reliability, the polarizer preferably contains boric acid. In addition, from the viewpoint of suppressing the occurrence of through cracks, the content of boric acid contained in the polarizer is preferably 22 wt% or less, more preferably 20 wt% or less, with respect to the total amount of the polarizer. From the viewpoint of tensile stability and humidification reliability, the boric acid content is preferably 10% by weight or more, more preferably 12% by weight or more, based on the total amount of the polarizer.

Typical examples of the thin polarizers include thin polarizers described in japanese patent No. 4751486, japanese patent No. 4751481, japanese patent No. 4815544, japanese patent No. 5048120, international publication No. 2014/077599, and international publication No. 2014/077636, and thin polarizers obtained by the production methods described in these documents.

As the thin polarizer, among the production methods including the step of stretching in a state of a laminate and the step of dyeing, from the viewpoint of being able to stretch to a high magnification to improve the polarizing performance, a thin polarizer obtained by a production method including the step of stretching in an aqueous boric acid solution as described in japanese patent No. 4751486, japanese patent No. 4751481, and japanese patent No. 4815544 is preferable, and a thin polarizer obtained by a production method including the step of stretching in an auxiliary gas atmosphere before stretching in an aqueous boric acid solution as described in japanese patent No. 4751481 and japanese patent No. 4815544 is particularly preferable. These thin polarizing films can be obtained by a production method including a step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as PVA-based resin) layer and a stretching resin base material in a state of a laminate and a step of dyeing. With this production method, even if the PVA-based resin layer is thin, it can be stretched while being supported by the resin base material for stretching without causing troubles such as breakage due to stretching.

Easy adhesion layer

In the polarizing film of the present invention, the polarizer and the transparent protective film are bonded to each other with the adhesive layer formed of a cured product layer of the active energy ray-curable adhesive composition interposed therebetween, but an easy-adhesion layer may be provided between the transparent protective film and the adhesive layer. The easy-adhesion layer can be formed using various resins having, for example, a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, silicones, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins may be used alone in 1 kind, or in combination of 2 or more kinds. In addition, other additives may be added to the formation of the easy adhesion layer. Specifically, a thickener, an ultraviolet absorber, an antioxidant, a stabilizer such as a heat stabilizer, and the like can be further used.

Generally, an easy-adhesion layer is provided on a transparent protective film in advance, and the easy-adhesion layer side of the transparent protective film is bonded to a polarizer via an adhesive layer. The easy adhesion layer can be formed by applying a material for forming the easy adhesion layer on the transparent protective film by a known technique and drying the applied material. 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 easy adhesion layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and further preferably 0.05 to 1 μm. In this case, the total thickness of the easy adhesion layer is preferably within the above range.

In the polarizing film of the present invention, an easy-adhesion layer containing a specific compound containing a boronic acid group may be formed on at least one of the surfaces to be bonded of the polarizer and the transparent protective film, and the polarizer and the transparent protective film may be laminated with an adhesive layer interposed therebetween. According to this configuration, the polarizing film can have good adhesion between the polarizer and the transparent protective film and the adhesive layer, and can maintain adhesion even under severe conditions such as immersion in water in a dew condensation environment.

Specifically, it is preferable that at least one of the surfaces to be bonded of the polarizer and the transparent protective film comprises a compound represented by the following general formula (1),

[ chemical formula 8]

(wherein X is a functional group containing a reactive group, R¹And R²Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group, or a heterocyclic group), and the compound represented by the general formula (1) is interposed between the polarizer and the adhesive layer and/or between the transparent protective film and the adhesive layer. The aliphatic hydrocarbon group includes a linear or branched alkyl group having 1 to 20 carbon atoms and optionally having a substituent, a cyclic alkyl group having 3 to 20 carbon atoms and optionally having a substituent, and an alkenyl group having 2 to 20 carbon atoms, the aryl group includes a phenyl group having 6 to 20 carbon atoms and optionally having a substituent, a naphthyl group having 10 to 20 carbon atoms and optionally having a substituent, and the heterocyclic group includes, for example, a group having a 5-or 6-membered ring containing at least one hetero atom and optionally having a substituent. They may be connected to each other to form a ring. In the general formula (1), as R¹And R²The alkyl group is preferably a hydrogen atom, a linear or branched alkyl group having 1 to 3 carbon atoms, and most preferably a hydrogen atom. In the polarizing film, the compound represented by the general formula (1) may be interposed between the polarizer and the adhesive layer and/or between the transparent protective film and the adhesive layer in an unreacted state, or may be interposed between the polarizer and the adhesive layer in a state in which each functional group is reacted. In addition, "polarizing mirror and lensThe phrase "at least one of the contact surfaces of the transparent protective film includes the compound represented by the general formula (1)" means that, for example, at least 1 molecule of the compound represented by the general formula (1) is present on the contact surface. However, in order to sufficiently improve the adhesion water resistance between the polarizer and the adhesive layer and between the transparent protective film, it is preferable to form the easy-adhesion layer on at least a part of the adhesion surface using an easy-adhesion composition containing the compound represented by the general formula (1), and it is more preferable to form the easy-adhesion layer on the entire surface of the adhesion surface.

In the following embodiments, an example in which an easy-adhesion layer is formed on at least a part of the bonding surface, that is, a polarizing film in which a transparent protective film is laminated on at least one surface of a polarizer via an adhesive layer, wherein the polarizing film includes an easy-adhesion layer formed using an easy-adhesion composition containing a compound represented by the above general formula (1) on at least one bonding surface of the polarizer and the transparent protective film, will be described.

X in the compound represented by the general formula (1) is a functional group containing a reactive group which is reactive with a curable component constituting the adhesive layer, and examples of the reactive group contained in X include: hydroxyl group, amino group, aldehyde group, carboxyl group, vinyl group, (meth) acryloyl group, styryl group, (meth) acrylamide group, vinyl ether group, epoxy group, oxetanyl group, α, β -unsaturated carbonyl group, mercapto group, halogen group, and the like. When the curable resin composition constituting the adhesive layer is active energy ray-curable, the reactive group contained in X is preferably at least 1 reactive group selected from a vinyl group, a (meth) acryloyl group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, and a mercapto group, and particularly when the curable resin composition constituting the adhesive layer is radically polymerizable, the reactive group contained in X is preferably at least 1 reactive group selected from a (meth) acryloyl group, a styryl group, and a (meth) acrylamide group, and when the compound represented by the general formula (1) has a (meth) acrylamide group, the reactivity is high, and the copolymerization rate with the active energy ray-curable resin composition is improved, and thus more preferable. In addition, since the (meth) acrylamide group has high polarity and excellent adhesiveness, it is also preferable from the viewpoint of efficiently obtaining the effects of the present invention. When the curable resin composition constituting the adhesive layer is cationically polymerizable, the reactive group contained in X preferably has at least 1 functional group selected from a hydroxyl group, an amino group, an aldehyde group, a carboxyl group, a vinyl ether group, an epoxy group, an oxetane group and a mercapto group, and particularly when the curable resin layer has an epoxy group, the obtained curable resin layer is excellent in adhesion to an adherend, and therefore preferably when the curable resin composition has a vinyl ether group, the curable resin composition is excellent in curability, and thus preferable.

Preferable specific examples of the compound represented by the general formula (1) include a compound represented by the following general formula (1'),

[ chemical formula 9]

(wherein Y is an organic group, X, R)¹And R²The same as described above). More preferred specific examples include the following compounds (1a) to (1 d).

[ chemical formula 10]

In the present invention, the compound represented by the general formula (1) may be a compound in which a reactive group is directly bonded to a boron atom, but as shown in the above-mentioned specific examples, the compound represented by the general formula (1) is preferably a compound in which a reactive group is bonded to a boron atom through an organic group, that is, a compound represented by the general formula (1'). When the compound represented by the general formula (1) is, for example, a compound bonded to a reactive group through an oxygen atom bonded to a boron atom, the adhesion water resistance of the polarizing film tends to be deteriorated. On the other hand, the compound represented by the general formula (1) is preferable because it has no boron-oxygen bond, has a boron-carbon bond by bonding to an organic group via a boron atom, and contains a reactive group (in the general formula (1'), because the adhesion water resistance of the polarizing film is improved. The organic group specifically means an organic group having 1 to 20 carbon atoms which may have a substituent, and more specifically, examples thereof include: a linear or branched alkylene group having 1 to 20 carbon atoms and optionally having a substituent, a cyclic alkylene group having 3 to 20 carbon atoms and optionally having a substituent, a phenylene group having 6 to 20 carbon atoms and optionally having a substituent, a naphthylene group having 10 to 20 carbon atoms and optionally having a substituent, and the like.

Examples of the compound represented by the general formula (1) include, in addition to the above-mentioned compounds, esters of boric acid and (meth) acrylic acid esters such as an ester of hydroxyethyl acrylamide, an ester of boric acid and hydroxymethyl acrylamide, an ester of hydroxyethyl acrylate, and an ester of boric acid and hydroxybutyl acrylate.

As described above, the polarizing film of the present invention is obtained by laminating a polarizer and a transparent protective film via an adhesive layer, wherein the adhesive layer is formed of a cured product layer obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray. In the present invention, particularly when the active energy ray-curable adhesive composition contains the acrylic oligomer (D), a compatible layer in which these layers change continuously can be formed between the transparent protective film and the adhesive layer. When the compatible layer is formed, the adhesion between the transparent protective film and the adhesive layer is improved. When the thickness of the compatible layer is P (μm) and the content of the acrylic oligomer (D) is Q wt% when the total amount of the composition is 100 wt%, the P × Q value is preferably less than 10. In the case of having such a configuration, the adhesive strength between the adhesive layer and the transparent protective film is particularly improved, which is preferable. On the other hand, when the content Q% by weight of the acrylic oligomer (D) is too high, the molecular weight of the acrylic oligomer (D) is generally large, and when a compatible layer is formed between the adhesive layer and the transparent protective film, the acrylic oligomer (D) hardly penetrates the transparent protective film side, and tends to concentrate at the interface between the adhesive layer and the compatible layer, and as a result, the acrylic oligomer (D) is likely to become a brittle layer. Since the brittle layer is likely to cause adhesive failure, it is preferable that at least the value of P × Q is designed to be less than 10 when the content of the acrylic oligomer (D) is Q% by weight. In addition, if the compatibility between the adhesive layer and the transparent protective film is excessively advanced and the thickness P (μm) of the compatible layer becomes excessively thick, a part of the compatible layer becomes a weak layer, and the adhesive strength between the adhesive layer and the transparent protective film is likely to be reduced. Therefore, it is preferable to design at least the value of P × Q to be less than 10 with respect to the thickness P (μm) of the compatible layer.

The polarizing film of the present invention comprises: a coating step of coating the active energy ray-curable adhesive composition described above on at least one surface of a polarizer and a transparent protective film; a bonding step of bonding the polarizer and the transparent protective film; and an adhesive step of bonding the polarizer and the transparent protective film via an adhesive layer obtained by curing an active energy ray-curable adhesive composition by irradiating the polarizer side or the transparent protective film side with an active energy ray.

The polarizer and the transparent protective film may be subjected to surface modification treatment before the coating step. It is particularly preferable to perform surface modification treatment on the surface of the polarizer. Examples of the surface modification treatment include corona treatment, plasma treatment, excimer treatment, and flame treatment, and corona treatment is particularly preferable. By performing the corona treatment, reactive functional groups such as carbonyl groups and amino groups are formed on the polarizer surface, and the adhesion to the curable resin layer is improved. Further, impurities on the surface can be removed by the ashing effect, or unevenness on the surface can be reduced, whereby a polarizing film having excellent appearance characteristics can be produced.

< coating Process >

The method of applying the active energy ray-curable adhesive composition may be appropriately selected depending on the viscosity of the composition and the target thickness, and examples thereof include: reverse coaters, gravure coaters (direct, reverse, or offset), bar reverse coaters, roll coaters, die coaters, wire wound bar coaters, and the like. The viscosity of the active energy ray-curable adhesive composition used in the present invention is preferably 3 to 100 mPas, more preferably 5 to 50 mPas, and most preferably 10 to 30 mPas. When the viscosity of the composition is high, the surface smoothness after coating is poor, and appearance is poor, which is not preferable. The active energy ray-curable adhesive composition used in the present invention can be applied by heating or cooling the composition to adjust the viscosity to a preferable range.

< bonding Process >

The polarizer and the transparent protective film are bonded to each other with the active energy ray-curable adhesive composition applied as described above. The polarizer and the transparent protective film may be bonded to each other by a roll laminator or the like.

< bonding Process >

After the polarizer and the transparent protective film are bonded, the active energy ray (e.g., electron beam, ultraviolet ray, visible light, etc.) is irradiated to cure the active energy ray-curable adhesive composition, thereby forming an adhesive layer. The irradiation direction of the active energy ray (electron beam, ultraviolet ray, visible light, etc.) may be any appropriate direction. Irradiation is preferably from the transparent protective film side. If the irradiation is performed from the polarizer side, the polarizer may be deteriorated by active energy rays (electron beams, ultraviolet rays, visible light, and the like).

The irradiation conditions in the case of irradiating an electron beam may be any conditions as long as the active energy ray-curable adhesive composition can be cured, and any suitable conditions may be adopted. For example, the acceleration voltage for electron beam irradiation is preferably 5kV to 300kV, and more preferably 10kV to 250 kV. If the acceleration voltage is less than 5kV, the electron beam may not reach the adhesive and may be insufficiently cured, and if the acceleration voltage is more than 300kV, the penetration force through the sample may be too strong and damage may be caused to the transparent protective film and the polarizer. The dose of the radiation is 5 to 100kGy, and more preferably 10 to 75 kGy. When the irradiation dose is less than 5kGy, the adhesive is insufficiently cured, and when it exceeds 100kGy, the transparent protective film and the polarizer are damaged, and the mechanical strength is reduced and the polarizer is yellowed, so that the optical characteristics cannot be obtained.

The electron beam irradiation is usually carried out in an inert gas, and may be carried out in an atmosphere with a small amount of oxygen introduced as required. Oxygen is introduced as appropriate depending on the material of the transparent protective film, and the surface of the transparent protective film which is in contact with the first electron beam is in contact with the oxygen, whereby oxygen inhibition occurs, damage to the transparent protective film can be prevented, and only the adhesive can be efficiently irradiated with an electron beam.

In the case of producing the polarizing film of the present invention, it is preferable to use, as the active energy ray, an active energy ray containing visible light in a wavelength range of 380nm to 450nm, particularly an active energy ray having the largest dose of visible light in a wavelength range of 380nm to 450 nm. When a transparent protective film (ultraviolet-opaque transparent protective film) having ultraviolet absorptivity and visible light is used, since light having a wavelength shorter than about 380nm is absorbed, the light having a wavelength shorter than 380nm does not reach the active energy ray-curable resin composition and does not contribute to the polymerization reaction. Further, light having a wavelength shorter than 380nm absorbed by the transparent protective film is converted into heat, and the transparent protective film itself generates heat, which causes defects such as curling and wrinkling of the polarizing film. Therefore, in the present invention, when ultraviolet light or visible light is used, it is preferable to use a device that does not emit light having a wavelength shorter than 380nm as the active energy ray generating device, and more specifically, the ratio of the cumulative illuminance in the wavelength range of 380 to 440nm to the cumulative illuminance in the wavelength range of 250 to 370nm is preferably 100:0 to 100:50, and more preferably 100:0 to 100: 40. In the case of producing the polarizing film of the present invention, a gallium-sealed metal halide lamp or an LED light source emitting light in a wavelength range of 380 to 440nm is preferable as the active energy ray. Alternatively, a light source containing ultraviolet rays and visible light such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, an incandescent lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a metal halide lamp, a fluorescent lamp, a tungsten lamp, a gallium lamp, an excimer laser, or sunlight may be used, or ultraviolet rays having a wavelength shorter than 380nm may be blocked by a band-pass filter and used. In order to improve the adhesion performance of the adhesive layer between the polarizer and the transparent protective film and to prevent curling of the polarizing film, it is preferable to use a gallium-sealed metal halide lamp and to use an active energy ray having a wavelength of 405nm obtained by using a band-pass filter capable of blocking light having a wavelength shorter than 380nm or an LED light source.

The active energy ray-curable adhesive composition is preferably heated before irradiation with ultraviolet rays or visible light (heating before irradiation), and in this case, it is preferably heated to 40 ℃ or higher, more preferably 50 ℃ or higher. In addition, it is also preferable to heat the active energy ray-curable adhesive composition after irradiation with ultraviolet rays or visible light (heating after irradiation), and in this case, it is preferable to heat the composition to 40 ℃ or higher, more preferably to 50 ℃ or higher.

The active energy ray-curable adhesive composition used in the present invention can be suitably used particularly when forming an adhesive layer in which a polarizer and a transparent protective film having a light transmittance of less than 5% at a wavelength of 365nm are adhered to each other. Here, the active energy ray-curable resin composition of the present invention contains the photopolymerization initiator of the general formula (2) and can be cured to form an adhesive layer by irradiating ultraviolet rays through a transparent protective film having UV absorbability. Therefore, even in a polarizing film in which transparent protective films having UV absorbing ability are laminated on both surfaces of a polarizer, the adhesive layer can be cured. However, it is needless to say that the adhesive layer can be cured also for a polarizing film in which a transparent protective film having no UV absorbing ability is laminated. The transparent protective film having UV absorption ability means a transparent protective film having a transmittance of light of 380nm of less than 10%.

Examples of the method for imparting UV absorption capability to the transparent protective film include: a method of incorporating an ultraviolet absorber into a transparent protective film, and a method of laminating a surface treatment layer containing an ultraviolet absorber on the surface of a transparent protective film.

Specific examples of the ultraviolet absorber include: conventionally known oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds, triazine compounds, and the like.

When the polarizing film of the present invention is produced by a continuous production line, the line speed varies depending on the curing time of the curable resin composition, and is preferably 1 to 500m/min, more preferably 5 to 300m/min, and still more preferably 10 to 100 m/min. When the linear velocity is too low, productivity is insufficient, or damage to the transparent protective film is too large, and a polarizing film that can withstand a durability test or the like cannot be produced. When the line speed is too high, the curing of the curable resin composition may be insufficient, and the desired adhesiveness may not be obtained.

In the method for producing a polarizing film of the present invention, an easy adhesion treatment step of forming an easy adhesion layer containing a specific boronic acid group-containing compound on at least one of the surfaces to be bonded of the polarizer and the transparent protective film may be provided before the coating step. Specifically, the polarizing film can be produced by a method for producing a polarizing film in which a transparent protective film is laminated on at least one surface of a polarizer with an adhesive layer interposed therebetween, the method comprising: an easy adhesion treatment step of adhering the compound represented by the general formula (1), more preferably the compound represented by the general formula (1'), to at least one of the bonding surfaces of the polarizer and the transparent protective film; a coating step of coating a curable resin composition on at least one of the bonding surfaces of the polarizer and the transparent protective film; a bonding step of bonding the polarizer and the transparent protective film; and an adhesive step of bonding the polarizer and the transparent protective film via an adhesive layer obtained by curing the curable resin composition by irradiating the polarizer side or the transparent protective film side with an active energy ray.

< easy adhesion treatment Process >

Examples of a method for forming an easy-adhesion layer on at least one of the bonding surfaces of the polarizer and the transparent protective film by using an easy-adhesion composition containing a compound represented by the general formula (1) include: a method for producing an easy-adhesion composition (A) containing a compound represented by the general formula (1) and applying the composition to at least one of the surfaces to be adhered of a polarizer and a transparent protective film. Examples of the easily adherable composition (a) that may be contained in addition to the compound represented by the general formula (1) include solvents and additives.

When the easy-adhesion composition (a) contains a solvent, the composition (a) may be applied to at least one of the bonding surfaces of the polarizer and the transparent protective film, and if necessary, a drying step and a curing treatment (heat treatment or the like) may be performed.

The solvent that can be contained in the easy-adhesion composition (a) is preferably one that can stably dissolve or disperse the compound represented by the general formula (1)A solvent. The solvent may be an organic solvent, water, or a mixed solvent thereof. The solvent may be selected from, for example: esters such as ethyl acetate, butyl acetate, and 2-hydroxyethyl acetate; ketones such as methyl ethyl ketone, acetone, cyclohexanone, methyl isobutyl ketone, diethyl ketone, methyl n-propyl ketone, and acetylacetone; tetrahydrofuran (THF), bisCyclic ethers such as alkanes; aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol and cyclohexanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and diethylene glycol monoethyl ether; glycol ether acetates such as diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; and so on.

Examples of additives that can be contained in the easy-adhesion composition (a) include: surfactant, plasticizer, tackifier, low molecular weight polymer, polymerizable monomer, surface lubricant, leveling agent, antioxidant, preservative, light stabilizer, ultraviolet absorbent, polymerization inhibitor, silane coupling agent, titanium coupling agent, inorganic or organic filler, metal powder, particle, foil and the like.

When the easy-adhesion composition (a) contains a polymerization initiator, the compound represented by the general formula (1) in the easy-adhesion layer may react before the adhesive layer is laminated, and the effect of improving the adhesion water resistance of the polarizing film, which is originally intended, may not be sufficiently obtained. Therefore, the content of the polymerization initiator in the easy-adhesion layer is preferably less than 2% by weight, more preferably less than 0.5% by weight, and particularly preferably no polymerization initiator is contained.

When the content of the compound represented by the general formula (1) in the easy-adhesion layer is too small, the proportion of the compound represented by the general formula (1) present on the surface of the easy-adhesion layer decreases, and the easy-adhesion effect may be lowered. Therefore, the content of the compound represented by the general formula (1) in the easy-adhesion layer is preferably 1% by weight or more, more preferably 20% by weight or more, and further preferably 40% by weight or more.

As a method for forming the easy adhesion layer on the polarizer using the easy adhesion composition (a), a method of directly immersing the polarizer in a treatment bath of the composition (a), or a known coating method can be suitably used. Specific examples of the coating method include: roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, and die coating, but are not limited thereto.

In the present invention, when the thickness of the easy adhesion layer provided in the polarizer is too large, the cohesive force of the easy adhesion layer may be reduced, and the easy adhesion effect may be reduced. Therefore, the thickness of the easy adhesion layer is preferably 2000nm or less, more preferably 1000nm or less, and further preferably 500nm or less. On the other hand, the lowest limit of the thickness for sufficiently exerting the effect of the easy adhesion layer is at least the thickness of the monomolecular film of the compound represented by the general formula (1), and is preferably 1nm or more, more preferably 2nm or more, and further preferably 3nm or more.

< optical film >

The polarizing film of the present invention can be practically used as an optical film laminated with another optical layer. The optical layer is not particularly limited, and examples thereof include: optical films such as retardation films (including wave plates such as 1/2 and 1/4), optical compensation films, brightness enhancement films, reflection plates, and reflection/transmission plates are optical layers used in the formation of liquid crystal display devices. In the present invention, these optical layers can be used as a base film of a base film with an easy-adhesion layer, and have reactive functional groups such as hydroxyl groups, carbonyl groups, and amino groups by performing surface modification treatment as necessary. Therefore, a retardation film with an easy-adhesion layer, which is formed on at least one surface of a retardation film having at least a reactive functional group on the surface thereof and is provided with a compound represented by the above general formula (1), particularly an easy-adhesion layer-attached retardation film with an easy-adhesion layer containing a compound represented by the above general formula (1), is preferable because the adhesiveness between the retardation film and the adhesive layer can be improved, and as a result, the adhesiveness is particularly improved.

As the retardation film, a retardation film having a retardation of 40nm or more in the front direction and/or 80nm or more in the thickness direction can be used. The front retardation is usually controlled to be in the range of 40 to 200nm, and the thickness direction retardation is usually controlled to be in the range of 80 to 300 nm.

As the phase difference plate, there are: birefringent films obtained by uniaxially or biaxially stretching a polymer material, alignment films of liquid crystal polymers, retardation plates obtained by supporting alignment layers of liquid crystal polymers with films, and the like. The thickness of the retardation film is not particularly limited, and is generally about 20 to 150 μm.

As the retardation film, a reverse wavelength dispersion type retardation film satisfying the following formulas (1) to (3) can be used:

0.70＜Re[450]/Re[550]＜0.97···(1)

1.5×10^-3＜Δn＜6×10^-3···(2)

1.13＜NZ＜1.50···(3)

(wherein Re 450 and Re 550 are in-plane retardation values of the retardation film measured by light having wavelengths of 450nm and 550nm at 23 ℃, respectively; Δ n is in-plane birefringence, nx-ny, where nx-NZ is the thickness-direction birefringence and nx-ny, where NZ is the thickness-direction refractive index of the retardation film, and NZ is the ratio of nx-NZ to nx-ny, where nx-NZ is the thickness-direction birefringence, and nx-ny is the in-plane birefringence) where the refractive indices of the retardation film in the slow axis direction and the fast axis direction are nx and ny, respectively).

The polarizing film or the optical film having at least 1 polarizing film laminated thereon may be provided with an adhesive layer for adhesion to other members such as a liquid crystal cell. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, and for example, a pressure-sensitive adhesive using a polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine polymer, or a rubber as a base polymer can be suitably selected and used. In particular, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive which is excellent in optical transparency, exhibits adhesive properties such as appropriate wettability, aggregability and adhesiveness, and is excellent in weather resistance, heat resistance and the like can be preferably used.

The adhesive layer may be provided on one side or both sides of the polarizing film, the optical film in the form of stacked layers of different compositions, kinds, or the like. In addition, when the polarizing film and the optical film are provided on both surfaces, adhesive layers having different compositions, kinds, thicknesses, and the like may be formed on the front and back surfaces of the polarizing film and the optical film. The thickness of the adhesive layer may be suitably determined depending on the purpose of use, adhesion, etc., and is usually 1 to 500. mu.m, preferably 1 to 200. mu.m, and particularly preferably 1 to 100. mu.m.

The exposed surface of the adhesive layer is temporarily covered with a separator by adhesion for the purpose of preventing contamination and the like until the adhesive layer is actually used. This prevents contact with the adhesive layer in a normal processing state. As the separator, a conventionally specified suitable separator such as a separator obtained by coating a suitable thin layer body such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, a net, a foamed sheet, a metal foil, or a laminate thereof with a suitable release agent such as silicone, long-chain alkyl, fluorine, or molybdenum sulfide, if necessary, can be used in addition to the above thickness conditions.

< image display device >

The polarizing film or optical film of the present invention can be preferably used for formation of various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to a conventional method. That is, the liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell with a polarizing film or an optical film and, if necessary, components such as an illumination system, and incorporating a driver circuit, and the like. As the liquid crystal cell, any type of liquid crystal cell such as TN type, STN type, pi type, or the like can be used.

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, a liquid crystal display device using a backlight or a reflector in an illumination system, or the like can be formed. In this case, the polarizing film or the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. In the case where a polarizing film or an optical film is provided on both sides, they may be the same or different. Further, in the formation of the liquid crystal display device, appropriate members such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight may be disposed in appropriate positions in 1 layer or 2 layers or more.