JPWO2013161826A1 - Radiation curable composition, adhesive, and polarizing plate - Google Patents

Abstract

The radiation curable composition of the present invention comprises (A) a compound having two or more alicyclic epoxy groups in the molecule, (B) a compound having three hydroxyl groups in the molecule, and (C) a photoacid generator, [The number of all alicyclic epoxy groups of (A) contained in the radiation curable composition / the total number of hydroxyl groups of (B) contained in the radiation curable composition] It is characterized by being less than 2.0. According to the said radiation curable composition, manufacture of a polarizing plate with high weather resistance can be enabled, maintaining the high adhesiveness of a protective film.

Description

  The present invention relates to a radiation curable composition, an adhesive, and a polarizing plate. In particular, the present invention relates to a radiation curable composition suitable as an adhesive for producing an optical member such as a polarizing plate, an adhesive, and a polarizing plate using them.

  In recent years, liquid crystal display devices have been widely used as display devices for displaying characters, images, and the like. Such a liquid crystal display device usually includes a liquid crystal cell composed of two polarizing plates and a glass substrate, a transparent electrode, a color filter, a light distribution film, a liquid crystal, and the like disposed therebetween. In general, a polarizing plate used in a liquid crystal display device is obtained by bonding a protective film such as a triacetyl cellulose film on one or both surfaces of a polarizing film (polarizer) obtained by adsorbing iodine or the like on a stretched and oriented polyvinyl alcohol sheet. It is formed by bonding through an agent layer. In recent years, from the viewpoint of power saving, there has been a movement to make the backlight of a liquid crystal display device into an LED, and for heat generation of the LED, the polarizing plate has been required to have heat and moisture resistance and thermal shock resistance. In particular, a polarizing plate using a triacetylcellulose-based film having a high moisture permeability as a protective film is not sufficiently resistant to the above, and therefore, an alternative to a film having a low moisture permeability is in progress.

  On the other hand, what has various hardening systems is known as a composition suitable for the adhesive agent used for manufacture of a polarizing plate. Among them, it is known that a curing reaction proceeds by heating, ultraviolet irradiation, etc., and those capable of forming an adhesive layer or film having a high crosslinking density can exhibit good adhesive strength and coating film strength. . As resin compositions that can be cured by heating, ultraviolet irradiation, or the like, radically polymerizable and cationically polymerizable resins are known.

  The radical polymerization of the resin composition may stop before the curing has sufficiently progressed, or may cause curing shrinkage as the polymerization reaction proceeds. On the other hand, although cationic polymerization is insufficient in terms of adhesive strength, it has the advantage that it does not cause radical termination reaction or deactivation, and the degree of curing shrinkage is small.

  Therefore, as a material applicable to an optical member such as a polarizing plate in which slight distortion of the base material is a problem, an alicyclic epoxy compound as a cationic polymerizable compound, a compound having at least two hydroxyl groups in the molecule In addition, it is known that an adhesive composition containing a photoacid generator can be cured in a short time and is excellent in performance such as adhesive strength (for example, see Patent Document 1).

JP-A-10-330717

  However, the polarizing plate using the adhesive has a problem that the protective film is peeled off in the heat and humidity resistance test and the thermal shock test. This was considered to be because the adhesive film was not sufficiently cured because the polarizing film absorbed the radiation. Therefore, there is a need for a polarizing plate having high weather resistance that is excellent in moist heat resistance and thermal shock resistance, and a radiation curable composition and an adhesive that enable production of such a polarizing plate.

  Accordingly, an object of the present invention is to provide a radiation curable composition and an adhesive that enable the production of a polarizing plate having high weather resistance while maintaining high adhesiveness of a protective film, or polarized light having high weather resistance. It is to provide a plate and to provide such a polarizing plate.

  Therefore, as a result of intensive studies by the present inventors to solve the above problems, the total number of epoxy groups of a specific epoxy compound contained in the composition and the total number of hydroxyl groups of the trifunctional alcohol contained in the composition By keeping the ratio within a certain range, it was found that the protective film of the polarizing plate was not peeled off even after the moisture and heat resistance test and the thermal shock test while maintaining the adhesiveness, and the present invention was completed. It was.

That is, the present invention
(A) a compound having two or more alicyclic epoxy groups in the molecule,
A radiation curable composition comprising (B) a compound having three hydroxyl groups in the molecule, and (C) a photoacid generator,
[The number of all alicyclic epoxy groups of (A) contained in the radiation curable composition / the total number of hydroxyl groups of (B) contained in the radiation curable composition] is less than 2.0. Radiation curable compositions are provided.

（上記式（Ｉ）中、Ｘは、単結合又は連結基を示す。）In the radiation curable composition,
(A) The compound having two or more alicyclic epoxy groups in the molecule is preferably a compound represented by the following formula (I).

(In the above formula (I), X represents a single bond or a linking group.)

In the radiation curable composition,
X is preferably a linking group containing an ester bond.

In the radiation curable composition,
(B) The compound having three hydroxyl groups in the molecule is preferably a polyester triol.

The present invention also provides:
An adhesive containing the radiation curable composition is provided.

  It is preferable that the adhesive does not contain a photosensitizer.

The present invention also provides:
An adhesive for polarizing plate containing the radiation curable composition is provided.

  The polarizing plate adhesive preferably does not contain a photosensitizer.

The present invention also provides:
Provided is a polarizing plate obtained by adhering a protective film to at least one surface of a polarizing film using the adhesive.

The polarizing plate is preferably a polarizing plate obtained by curing the adhesive by irradiation with radiation with an irradiation light amount of 300 mJ / cm ² or less.

  According to the radiation curable composition and adhesive of the present invention, a polarizing plate obtained by adhering a protective film using these is polarized even after a moist heat resistance test and a thermal shock test while maintaining high adhesiveness of the protective film. Peeling of the protective film on the plate does not occur and reliability can be ensured.

[Radiation curable composition]
The radiation curable composition of the present invention comprises:
(A) a compound having two or more alicyclic epoxy groups in the molecule,
A radiation curable composition comprising (B) a compound having three hydroxyl groups in the molecule, and (C) a photoacid generator,
[A total number of alicyclic epoxy groups of (A) contained in the radiation curable composition / total number of hydroxyl groups of (B) contained in the radiation curable composition] may be less than 2.0. The point is not particularly limited.

  In the radiation curable composition of the present invention, [number of all alicyclic epoxy groups of (A) contained in the radiation curable composition / number of total hydroxyl groups of (B) contained in the radiation curable composition] is 2. The reason why the above effect is exhibited by being less than 0.0 is unclear, but as the mechanism, the reactivity with a precursor in which a cationic species is added to an epoxy group is as follows: Therefore, it can be presumed that an adhesive layer in which (A) and (B) are polymerized with each other is immediately formed, and an anchor effect on the adhesion surface is expressed and adsorbed. Commonly speaking, if the epoxy group number / hydroxyl group number is less than 2.0, it is said that curing is insufficient, but as a compound having a hydroxyl group, by using a compound having three hydroxyl groups in the molecule, It has been found that curing can be performed sufficiently. In addition, the said adsorption | suction mechanism is estimation, and even if it does not follow the said mechanism, if the requirements prescribed | regulated by this invention are satisfied, it will be included in the technical scope of this invention.

  In the radiation curable composition of the present invention, [the number of all alicyclic epoxy groups in (A) contained in the radiation curable composition / the total number of hydroxyl groups in (B) contained in the radiation curable composition] is 2. However, when the total number of hydroxyl groups in (B) is too large, the weather resistance is likely to be lowered. 9 is more preferable, and 1.0 to 1.8 is particularly preferable.

  In the radiation curable composition of the present invention, the mixing ratio of (A) a compound having two or more alicyclic epoxy groups in the molecule and (B) a compound having three hydroxyl groups in the molecule is not particularly limited. However, from the viewpoint of curability, the mass ratio is preferably 30:70 to 70:30 (the former: the latter), more preferably 40:60 to 60:40 (the former: the latter), and 45: It is particularly preferably 55 to 55:45 (the former: the latter).

  The viscosity of the radiation curable composition of the present invention is not particularly limited, but is preferably 40 to 800 mPa · s, more preferably 40 to 500 mPa · s from the viewpoint of coating workability.

[(A) Compound having two or more alicyclic epoxy groups in the molecule]
An alicyclic epoxy group means an epoxy group composed of two adjacent carbon atoms and oxygen atoms constituting the alicyclic ring.

  (A) As a compound which has two or more alicyclic epoxy groups in a molecule | numerator, only 1 type may be used and 2 or more types may be mixed and used.

(A) The compound having two or more alicyclic epoxy groups in the molecule is preferably a compound having a cyclohexene oxide group from the viewpoints of transparency and heat resistance, and in particular, a compound represented by the following formula (I) Is preferred.

  In the above formula (I), X represents a single bond or a linking group (a divalent group having one or more atoms). Examples of the linking group include a divalent hydrocarbon group, a carbonyl group, an ether bond, an ester bond, a carbonate group, an amide group, and a group in which a plurality of these are linked.

  Examples of the alicyclic epoxy compound in which X in the formula (I) is a single bond include 3,4,3 ′, 4′-diepoxybicyclohexane and the like.

  As said bivalent hydrocarbon group, a C1-C18 linear or branched alkylene group, a bivalent alicyclic hydrocarbon group, etc. are mentioned. Examples of the linear or branched alkylene group having 1 to 18 carbon atoms include a methylene group, a methylmethylene group, a dimethylmethylene group, an ethylene group, a propylene group, and a trimethylene group. Examples of the divalent alicyclic hydrocarbon group include 1,2-cyclopentylene group, 1,3-cyclopentylene group, cyclopentylidene group, 1,2-cyclohexylene group, 1,3-cyclopentylene group, And divalent cycloalkylene groups (including cycloalkylidene groups) such as a cyclohexylene group, a 1,4-cyclohexylene group, and a cyclohexylidene group.

  As the linking group X, a linking group containing an oxygen atom is particularly preferable. Specifically, -CO-, -O-CO-O-, -COO-, -O-, -CONH-; A group in which a plurality of groups are linked; a group in which one or more of these groups are linked to one or more of divalent hydrocarbon groups, and the like. From the viewpoint of adhesion to an adherend, an ester A linking group having a bond (—COO—) is particularly preferred. Examples of the divalent hydrocarbon group include those exemplified above.

Typical examples of the alicyclic epoxy compound represented by the above formula (I) include compounds represented by the following formulas (I-1) to (I-10). In the following formulas (I-5) and (I-7), l and m each represent an integer of 1 to 30. R in the following formula (I-5) is an alkylene group having 1 to 8 carbon atoms, methylene group, ethylene group, propylene group, isopropylene group, butylene group, isobutylene group, s-butylene group, pentylene group, hexylene. And linear or branched alkylene groups such as a group, a heptylene group, and an octylene group. Among these, C1-C3 linear or branched alkylene groups, such as a methylene group, ethylene group, a propylene group, an isopropylene group, are preferable. N1 to n6 in the following formulas (I-9) and (I-10) each represent an integer of 1 to 30. Among them, the compound (I-1) (celloxide 2021P or the like) is used alone, or the compound (I-1) (celloxide 2021P or the like) and an alicyclic epoxy compound represented by other formula (I) are used. It is preferable to use together.

[(B) Compound having three hydroxyl groups in the molecule]
(B) Examples of the compound having three hydroxyl groups in the molecule include polyester triol, glycerin, trimethylol ethane, trimethylol propane, adamantane triol, and the like, but are not particularly limited, but are esters from the viewpoint of compatibility with epoxy compounds. Polyester triols containing groups are preferred and polycaprolactone triols are particularly preferred.

  (B) As a compound which has three hydroxyl groups in a molecule | numerator, only 1 type may be used and 2 or more types may be mixed and used.

上記式（ＩＩ）において、
ａ、ｂ、ｃは、いずれも１以上の整数であり、それぞれ、例えば１〜３０、好ましくは１〜１０の範囲内であり、ａ＋ｂ＋ｃは好ましくは３〜３０の範囲内であり、
Ｒ¹は、３価の炭化水素基、好ましくは３価の脂肪族炭化水素基であり、Ｒ¹の炭素数は好ましくは３〜２０、より好ましくは３〜１５、さらに好ましくは３〜１０の範囲内であり、Ｒ¹の代表例としては、以下の式（ＩＩＩ−１）〜（ＩＩＩ−４）で表される３価の炭化水素基等が挙げられる。

The polycaprolactone triol is not particularly limited, but a compound represented by the following formula (II) is preferable.

In the above formula (II),
a, b and c are all integers of 1 or more, and are each in the range of, for example, 1 to 30, preferably 1 to 10, and a + b + c is preferably in the range of 3 to 30,
R ¹ is a trivalent hydrocarbon group, preferably a trivalent aliphatic hydrocarbon group, and R ¹ preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, still more preferably 3 to 10 carbon atoms. A typical example of R ^{1 that} falls within the range includes trivalent hydrocarbon groups represented by the following formulas (III-1) to (III-4).

  Examples of commercially available products of polycaprolactone triol include Plaxel 303, Plaxel 305, Plaxel 308, Plaxel 312, Plaxel L312AL, Plaxel 320, Plaxel 320ML, Plaxel L320AL, Plaxel L330AL; Among them, polycaprolactone triol, particularly Plaxel 305, which is liquid at room temperature is preferable from the viewpoint of easy mixing and no fear of precipitation.

[(C) Photoacid generator]
(C) Although it does not restrict | limit especially as a photo-acid generator, The thing which generate | occur | produces an acid by ultraviolet irradiation and has an effect | action which starts cationic polymerization by the generated acid is preferable.

  Examples of the photoacid generator include sulfonium salts (particularly, triarylsulfonium salts) such as triarylsulfonium hexafluorophosphate (eg, p-phenylthiophenyldiphenylsulfonium hexafluorophosphate) and triarylsulfonium hexafluoroantimonate. ); Diaryl iodonium hexafluorophosphate, diaryl iodonium hexafluoroantimonate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, iodonium [4- (4-methylphenyl-2-methylpropyl) phenyl] hexafluorophosphate, etc. Iodonium salts; phosphonium salts such as tetrafluorophosphonium hexafluorophosphate; N-hexylpyri Pyridinium salts such as tetrafluoroborate and the like. These can be used alone or in combination of two or more.

  In the present invention, for example, commercially available products such as trade names “CPI-100P” and “CPI-101A” (manufactured by San Apro) may be used.

  As the amount of the photoacid generator used, the total amount of (A) a compound having two or more alicyclic epoxy groups in the molecule and (B) a compound having three hydroxyl groups in the molecule is 100 parts by mass. For example, it is about 1 to 20 parts by mass, preferably 4 to 10 parts by mass. When the usage-amount of a photo-acid generator is less than the said range, the problem of the adhesive force deficiency by a cure failure and the fall of a weather resistance may arise. On the other hand, when the amount of the photoacid generator used exceeds the above range, the water resistance may deteriorate due to the high concentration of the ionic substance after curing.

[Other ingredients]
In addition to the components (A) to (C), the radiation curable composition of the present invention is preferably an organic solvent for adjusting viscosity (an organic solvent capable of cationic curing, specifically, 1,3-butanediol, Celoxide 2000, etc., all of which are manufactured by Daicel as specific examples of commercially available products), inorganic fillers for improving adhesive strength and screen printability (for example, Spherical silica manufactured by Denki Kagaku Kogyo Co., Ltd., such as FB-5SDC, FB-3SDC, etc., and silane coupling agents that improve adhesion strength (eg, Evonik Degussa Japan Co., Ltd., Dynasylan AMEO, Dynasylan GLYMO, etc.) ), Leveling agents that improve coating performance (for example, BYK-307, BYK-333, etc., manufactured by BYK Japan, Inc.) and other additives are included within a range that does not interfere with the effects of the present invention. It may be.

[adhesive]
The adhesive of this invention should just contain the said radiation-curable composition, and is not restrict | limited in particular at another point.

  As described in Japanese Patent Application Laid-Open No. 2008-257199 or Japanese Patent Application Laid-Open No. 2011-28234, there is an attempt to increase curability by adding a photosensitizer to an adhesive. However, although the photosensitizer increases curability, there is a risk of an increase in viscosity due to room lighting during work. Since the adhesive of the present invention has improved curability by blending (B) a compound having three hydroxyl groups in the molecule, there is little increase in viscosity due to room lighting during work, and the use for a polarizing plate From the viewpoint of making it particularly useful, it is preferable not to contain a photosensitizer.

[Polarizer]
The polarizing plate of this invention should just be a polarizing plate formed by adhere | attaching a protective film on the at least one surface of a polarizing film using the said adhesive agent, and is not restrict | limited in particular at another point.

As a method for producing a polarizing plate by adhering a protective film to at least one surface of the polarizing film using, for example, an adhesive between the polarizing film and the protective film by a conventionally known method, for example. After applying and pressure-bonding the protective film and the polarizing film coated with an adhesive by a roller or the like, light (radiation) including i-line (365 nm), h-line (405 nm), g-line (436 nm), etc. Is irradiated with an illuminance of 10 to 1200 mW / cm ² and an irradiation light quantity of 20 to 2500 mJ / cm ² to cure the photocurable adhesive composition, whereby a polarizing plate can be obtained. From the viewpoint of suppressing deterioration of the protective film and the polarizing film due to radiation such as ultraviolet rays and from the viewpoint of productivity, the irradiation light amount is preferably ^{20 to} 600 mJ / cm ² , more preferably ²⁰ to 300 mJ / cm ² . In particular, when the irradiation light quantity is 300 mJ / cm ² or less, there is a great advantage that the deterioration of the protective film and the polarizing film due to the radiation is dramatically reduced. Further, after applying an adhesive on at least one surface of the polarizing film with a bar coater, roll coater, gravure roll, etc. and attaching a protective film, radiation including i-line, h-line, g-line, etc. A polarizing plate can be obtained by irradiating and curing the photocurable adhesive composition in the same manner as in the above case. It is also possible to obtain a polarizing plate by applying an adhesive between the protective film and the polarizing film (upper and lower two layers), and irradiating and adhering radiation from one side in the same manner as described above. When viewed from the radiation side, the UV light reaches only about one-third of the light on the lower surface of the polarizing film. (B) Improved curability by compounding with a compound having three hydroxyl groups in the molecule. The adhesive of the present invention is particularly useful.

[Polarizing film]
The polarizing film is not particularly limited, and specific examples include a polyvinyl alcohol polarizing film produced by adsorbing a dichroic dye on a polyvinyl alcohol resin film and uniaxially stretching the dichroic dye.

  The polyvinyl alcohol resin used for the polarizing film is usually obtained by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, and vinyl ethers. The saponification degree of the polyvinyl alcohol-based resin is not particularly limited, but is preferably about 85 to 100 mol%. The polyvinyl alcohol resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is not particularly limited, but is preferably about 1,000 to 10,000.

  However, the polyvinyl alcohol resin is not limited to those obtained by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, and a small amount of unsaturated carboxylic acid (including salts, esters, amides, nitriles, etc.) , Modified polyvinyl alcohols containing components copolymerizable with vinyl acetate, such as olefins having 2 to 30 carbon atoms (including ethylene, propylene, n-butene, isobutene, etc.), vinyl ethers, unsaturated sulfonates, etc. Resin or the like may be used.

  The weight average molecular weight of the polyvinyl alcohol-based resin is not particularly limited, but is preferably 60000 to 300000.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method.

  The method for producing the polarizing film is not particularly limited. For example, a step of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, a polyvinyl alcohol type on which the dichroic dye is adsorbed It is manufactured by a manufacturing method including a step of treating a resin film with a boric acid aqueous solution, a step of uniaxially stretching a polyvinyl alcohol-based resin film, and the like. The step of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, and the step of treating the polyvinyl alcohol resin film adsorbed with the dichroic dye with an aqueous boric acid solution are simultaneously performed. You can go.

  Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing, or may be performed after dyeing. In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, it may be dry stretching such as stretching in the air, or may be wet stretching in which stretching is performed in a state swollen with a solvent. The draw ratio is preferably about 1.5 to 10 times.

  For example, the polyvinyl alcohol resin film is dyed with a dichroic dye by immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. Although it does not restrict | limit especially as a dichroic pigment | dye, For example, an iodine, a dichroic organic dye, etc. are used.

  The dyeing method when iodine is used as the dichroic dye is not particularly limited. For example, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is employed. The iodine content in this aqueous solution is preferably about 0.01 to 0.5 parts by mass with respect to 100 parts by mass of water, and the potassium iodide content is preferably with respect to 100 parts by mass of water. About 0.5 to 10 parts by mass. The immersion time (dyeing time) in this aqueous solution is preferably about 30 to 300 seconds.

  The boric acid treatment after dyeing with a dichroic dye is performed by immersing the polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The boric acid content in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight with respect to 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually about 1 to 20 parts by weight with respect to 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 10 to 1200 seconds.

  As described above, it is possible to produce a polarizing film in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol-based resin film. The thickness of the polarizing film can be about 10 to 40 μm.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[1. Preparation of radiation curable composition for adhesive]
Components (A) to (C) were added to a container equipped with a stirrer at the blending ratio (mass ratio) shown in Table 1, and stirred for 4 hours to mix uniformly. Stirring was stopped and the mixture was allowed to stand for 24 hours to obtain radiation curable compositions used in Examples 1 to 3. Similarly, the radiation curable composition used for Comparative Examples 1-7 was obtained.

In addition, the compound name of each component in Table 1 is as follows.
Component (A) Celoxide 2021P: 3,4-epoxycyclohexenylmethyl (3 ′, 4′-epoxy) cyclohexanecarboxylate [3,4-epoxycyclohexylmethyl (3,4-epoxy) cyclohexanecarboxylate, manufactured by Daicel Corporation]
Celoxide 3000: 1, 2: 8,9-diepoxy limonene (Daicel)
Epolide PB3600: Epoxidized polybutadiene (liquid) (Daicel)
Component (B) Placcel 205: Polycaprolactone diol (molecular weight 530) (manufactured by Daicel)
PLACCEL 305: polycaprolactone triol (molecular weight 550) (Daicel)
(C) Component CPI-100P: Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate (manufactured by San Apro)

[2. Production or preparation of adhesive substrate]
[Polarizing film (PVA film)]
A staining solution was prepared by dissolving 20 parts by mass of boric acid, 0.2 parts by mass of iodine, and 0.5 parts by mass of potassium iodide in 480 parts by mass of water. A PVA film (Vinylon film # 40, manufactured by Aicello) was immersed in this dyeing solution for 30 seconds, and then the film was stretched twice in one direction and dried to prepare a PVA film having a thickness of 30 μm.

[Protective film]
As a protective film, acryl viewer (PMMA film, manufactured by Nippon Shokubai Co., Ltd.) was used. The protective film was subjected to corona discharge treatment on the film surface with a discharge amount of 320 W · min / m ² using a corona surface treatment device (“Corona Surface Modification Evaluation Device (TEC-4AX)” manufactured by Kasuga Electric Co., Ltd.). And adhesion was carried out within 1 hour after the surface treatment.

[3. Production of polarizing plate]
[Examples 1 to 3, Comparative Examples 1 to 7]
The obtained radiation curable composition is coated on an acrylic (protective film) using a wire bar coater # 3, and a PVA film is pasted thereon using a metal roller so that bubbles and other defects do not enter. Combined. Next, the radiation curable composition is applied onto an acrylic viewer (protective film) using a wire bar coater # 3, and bonded to the bonded PVA film so that defects such as bubbles do not enter. did. On a glass plate, a four-way despite bonded taped, high pressure mercury lamp (UVC-02516S1AA02: manufactured by Ushio Inc., illuminance 120 mW / cm ^2, irradiation amount 199mJ / cm ²⁾ was irradiated with light.

[4. Evaluation]
The adhesion (peeling strength) of the obtained polarizing plate, the appearance of the polarizing plate after the wet heat test (wet heat resistance), and the appearance of the polarizing plate after the temperature shock test (thermal shock resistance) were evaluated by the following methods. The results are shown in Table 1. In addition, [the number of all the alicyclic epoxy groups of (A) contained in the radiation curable composition / the total number of hydroxyl groups of (B) contained in the radiation curable composition] of the obtained radiation curable composition] These are also shown in Table 1 as [total number of epoxy groups] / [total number of hydroxyl groups].

(Adhesive evaluation)
The adhesiveness (peeling strength) of the produced polarizing plate was measured according to “JISK6854-4 adhesive-peeling adhesive strength test method part 4: floating roller method”. The produced polarizing temporary was fixed on a metal plate (stainless steel, dimensions: length 200 mm, width 25 mm, thickness 1.5 mm) with a double-sided adhesive tape (ST-416P, manufactured by Sumitomo 3M). In the polarizing plate, the end in the longitudinal direction was peeled between the PVA film and the protective film using a cutter knife. According to the JIS method, the sample is attached to a floating roller, the edge of the peeled film sample is fixed to the grip of the tensile tester, and the grip is lifted at a speed of 300 mm / min using the tensile tester, and the film is peeled off. The average peel force (N / 25 mm) was measured, and the adhesiveness (peel strength) was determined as follows. The results are shown in Table 1.
○: The measured average peel force was 2 N / 25 mm or more. X: The measured average peel force was less than 2 N / 25 mm.

(Evaluation of wet heat resistance and thermal shock resistance)
A wet heat test or a temperature impact test was performed as follows, and the wet and heat resistance and thermal shock resistance of the polarizing plate were evaluated by visually observing the polarizing plate before and after the test. As evaluation criteria for heat and humidity resistance and thermal shock resistance, the appearance of the polarizing plate after the wet heat test and the appearance of the polarizing plate after the temperature shock test were determined as follows. The results are shown in Table 1.
○: There was no change in the polarizing plate before and after the test. ×: The polarizing plate after the test had color loss of the polarizing plate and peeling of the protective film.

(Moist heat test)
The wet heat test was conducted under conditions of a temperature of 60 ° C., a relative humidity of 90%, and 500 hours.

(Temperature shock test)
The wet heat test was performed under conditions of a temperature of −40 ° C. to 80 ° C., one cycle of 30 minutes, and 100 cycles.

  Examples 1 to 3 wherein [the number of all alicyclic epoxy groups of (A) contained in the radiation curable composition / the total number of hydroxyl groups of (B) contained in the radiation curable composition] is less than 2.0. Was excellent in adhesiveness, moist heat resistance and thermal shock resistance. Comparative Examples 1 and 2 wherein [the number of all alicyclic epoxy groups of (A) contained in the radiation curable composition / the total number of hydroxyl groups of (B) contained in the radiation curable composition] is 2.0 or more. Although the adhesiveness was excellent, the heat-and-moisture resistance and thermal shock resistance were insufficient. Moreover, as seen in Comparative Examples 3 to 5, [the number of all alicyclic epoxy groups of (A) contained in the radiation curable composition / the total number of hydroxyl groups of (B) contained in the radiation curable composition] ] Is less than 2.0, since (B) is bifunctional, the heat resistance and thermal shock resistance are insufficient due to insufficient crosslinking. In Comparative Example 6, Celoxide 3000 having only one alicyclic epoxy group in the molecule had insufficient adhesiveness in addition to heat and moisture resistance and thermal shock resistance due to insufficient curing. In Comparative Example 7, since a compound having an epoxy group that is not alicyclic was used, the adhesiveness was good, but the moist heat resistance and thermal shock resistance were insufficient.

  According to the radiation curable composition and adhesive of the present invention, a polarizing plate obtained by adhering a protective film using these is polarized even after a moist heat resistance test and a thermal shock test while maintaining high adhesiveness of the protective film. Since the protective film of the plate does not peel off and reliability can be secured, it is particularly useful as a material applicable to optical members such as polarizing plates.

Claims (10)

(A) a compound having two or more alicyclic epoxy groups in the molecule,
A radiation curable composition comprising (B) a compound having three hydroxyl groups in the molecule, and (C) a photoacid generator,
[The number of all alicyclic epoxy groups of (A) contained in the radiation curable composition / the total number of hydroxyl groups of (B) contained in the radiation curable composition] is less than 2.0. Radiation curable composition. (A) The radiation-curable composition according to claim 1, wherein the compound having two or more alicyclic epoxy groups in the molecule is a compound represented by the following formula (I).

(In the above formula (I), X represents a single bond or a linking group.)   The radiation-curable composition according to claim 2, wherein X is a linking group containing an ester bond.   (B) The radiation curable composition according to any one of claims 1 to 3, wherein the compound having three hydroxyl groups in the molecule is a polyester triol.   The adhesive agent containing the radiation-curable composition of any one of Claims 1-4.   6. The adhesive according to claim 5, which does not contain a photosensitizer.   The adhesive agent for polarizing plates containing the radiation curable composition of any one of Claims 1-4.   The adhesive for polarizing plates according to claim 7, which does not contain a photosensitizer.   The polarizing plate formed by adhere | attaching a protective film on the at least one surface of a polarizing film using the adhesive agent of Claim 5 or 6. The polarizing plate according to claim 9, wherein the adhesive is cured by irradiation with an irradiation light amount of 300 mJ / cm ² or less.