KR20110000525A - Polarizing plate and laminate optical member using the same - Google Patents

Abstract

PURPOSE: A polarizing plate and a layered optical member using the same are provided to represent the color of a polarizer as the neutral gray while maintaining the adhesion strength between a polarizer and a protection layer. CONSTITUTION: A polarizing plate is made of the polyvinyl alcohol resin aligned with the two color pigment. The protective film is welded with the transparent resin by the adhesive layer. The adhesive layer comprises cation polymerizing compound, optical cation polymerization initiator, and naphthalene photo intensifying assistant agent.

Description

POLARIZING PLATE AND LAMINATE OPTICAL MEMBER USING THE SAME}

This invention relates to the polarizing plate by which the protective film which consists of transparent resin was bonded to the polarizer which consists of polyvinyl alcohol-type resin. This invention also relates to the laminated optical member which laminated | stacked this polarizing plate on the other optical layer.

A polarizing plate is useful as one of the optical components which comprise a liquid crystal display device. The polarizing plate usually has a structure in which a protective film is laminated on both surfaces of a polarizer and is inserted in a liquid crystal display device. It is also known to provide a protective film only on one surface of the polarizer, but in most cases, a layer having an optical function is bonded to the other surface as a separate function instead of a simple protective film. Moreover, as a manufacturing method of a polarizer, the method of carrying out boric acid treatment of a uniaxially stretched polyvinyl alcohol-type resin film dyed with a dichroic dye, washing with water, and then drying is widely adopted.

Usually, a protective film is bonded immediately to a polarizer immediately after the above-mentioned water washing and drying. This is because the polarizer after drying has a weak physical strength, and once it is wound, it tends to be torn in the processing direction. Therefore, usually after drying, a water-based adhesive which is an aqueous solution of polyvinyl alcohol-based resin is immediately applied to the polarizer, and a protective film is simultaneously bonded to both surfaces of the polarizer via the adhesive. According to the convention, a triacetyl cellulose film having a thickness of 30 to 100 µm is used as the protective film.

The triacetyl cellulose has high moisture permeability, and the polarizing plate bonded thereto as a protective film has a problem of causing deterioration under moist heat, for example, under conditions such as a temperature of 70 ° C. and a relative humidity of 90%. Therefore, it is also known to use amorphous polyolefin resin which has lower moisture permeability than triacetyl cellulose, for example, norbornene-type resin as a protective film.

When bonding the protective film which consists of resin with low moisture permeability to a polyvinyl alcohol-type polarizer, adhesive strength in the aqueous solution of the polyvinyl alcohol-type resin generally used as an adhesive agent for bonding a polyvinyl alcohol-type polarizer and a triacetyl cellulose conventionally Was insufficient, or the appearance of the resulting polarizing plate became poor. This is because the resin film having a low moisture permeability is generally hydrophobic or a water vapor having low moisture permeability cannot be sufficiently dried as a solvent. On the other hand, it is also known to bond different kinds of protective films to both surfaces of the polarizer. For example, one side of the polarizer is bonded to a protective film made of a resin having low moisture permeability such as amorphous polyolefin resin, and the other side of the polarizer is bonded to the other side of the polarizer. And a protective film made of a resin having high moisture permeability, such as cellulose resins including triacetyl cellulose.

Therefore, it is active as an adhesive that provides a high adhesion between the protective film made of a resin with low moisture permeability and a polyvinyl alcohol polarizer, and also provides a high adhesion between a polyvinyl alcohol polarizer and a high moisture-permeable resin such as cellulose resin. Attempts have been made to use energy radiation curable adhesives. For example, Japanese Unexamined Patent Application Publication No. 2004-245925 discloses an adhesive mainly containing an epoxy compound that does not contain an aromatic ring, and cures the adhesive in cationic polymerization by irradiation of active energy rays. Adhesion of a protective film is proposed. In addition, Japanese Patent Application Laid-Open No. 2008-257199 discloses a combination of an alicyclic epoxy compound and an epoxy compound having no alicyclic epoxy group, and using a photocurable adhesive compounded together with a photocationic polymerization initiator for adhesion between a polarizer and a protective film. Techniques are disclosed. Japanese Laid-Open Patent Publication No. 2008-257199 describes using a photosensitizer containing an anthracene compound in combination to provide good adhesion even when the protective film contains an ultraviolet absorber.

That is, although a photocationic polymerization initiator is mix | blended in order to harden a cationically polymerizable compound like an epoxy compound, since such a photocationic polymerization initiator is a compound which shows the maximum absorption in the wavelength region generally 300 nm or shorter than that, By incorporating a photosensitizer exhibiting maximum absorption into light of a longer wavelength region, specifically, a wavelength longer than 380 nm, it is sensitive to light at a wavelength in the vicinity thereof and promotes the generation of cationic species or Lewis acids from the photocationic polymerization initiator. You can.

In addition, it is generally desired that the polarizing plate is neutral gray so that the original color can be displayed when applied to a liquid crystal display device. For example, Japanese Patent Laid-Open No. 2002-169024 discloses a ^* and b ^* of parallel colors so that a more neutral white display and a black display are possible, and a white display is bright and a high contrast display is obtained. And polarizing plates in which a ^* and b ^* of orthogonal colors satisfy specific relations have been proposed.

On the other hand, various improvements have also been made to general photocurable compositions used in fields other than polarizing plates. For example, International Publication WO 2006/073021 discloses an anthracene compound, a naphthalene compound, or a benzene compound in combination to form a photosensitizer. Techniques are disclosed. This international publication WO 2006/073021 discloses that a cationic polymerizable monomer and a photo cationic polymerization initiator are blended with the above photosensitizer to form a photocurable composition, and an epoxy compound is also used as an example of the cationic polymerizable monomer. Is disclosed.

A polarizer and a protective film can be firmly adhere | attached by using the adhesive agent which mix | blended the epoxy compound, the photocationic polymerization initiator, and the anthracene-type photosensitizer as disclosed in the said Unexamined-Japanese-Patent No. 2008-257199, an example For example, the polarizing plate which bonded the protective film to the polarizer using this adhesive does not affect a protective film or an adhesive bond layer, but shows high polarization degree according to the polarization degree which a polarizer originally shows, for example, even after performing a wet heat test, The degree of polarization is maintained. However, in order to fully express such an effect, it is necessary to mix | blend a certain amount of anthracene type photosensitizer. In this case, since the anthracene-based photosensitizer exhibits maximum absorption to light having a wavelength exceeding 380 nm, when the polarizing plate is placed in cross nicol, so-called blue light leaks when blue light around 400 nm is leaked. There was a problem that was growing. There is such a problem, and when a polarizing plate produced by using an adhesive in which anthracene-based photosensitizer is incorporated in a large amount is observed under cross nicol, it has become clear that the color of transmitted light is shifted from the neutral gray to the blue direction. In addition, when the amount of anthracene-based photosensitizer was blended to some extent, it became clear that the color under cross nicol also changed by the wet heat test.

Therefore, the subject of this invention is a polarizing plate which bonded the protective film to the polarizer using the adhesive agent in which the cationic polymerizable compound like an epoxy compound was mixed with the photosensitizer which shows absorption in comparatively long wavelength also in the ultraviolet region like an anthracene type-compound, It is to provide a polarizing plate excellent in moisture and heat resistance while maintaining the neutral gray when arranged in cross nicol. Another object of the present invention is to provide another laminated optical member which is excellent in moisture and heat resistance by laminating another optical layer on the polarizing plate.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve such a subject, the present inventors discovered that the photocurable adhesive composition which mix | blended the cationic polymerizable compound with the photocationic polymerization initiator and the photosensitizer which shows absorption in comparatively long wavelength also in an ultraviolet region is specific photosensitizing aids. By mixing a predetermined amount and using it for bonding the polarizer and the protective film, the polarizer and the protective film were firmly adhered while maintaining the neutral gray of the polarizer, and the polarizing plate excellent in moisture and heat resistance was also found to complete the present invention. . In particular, when the alicyclic epoxy compound and the aliphatic epoxy compound were mixed at a predetermined ratio as the cationically polymerizable compound, it was found that such a prescription was effective.

That is, this invention is equipped with the protective film which consists of a polarizer which consists of a polyvinyl alcohol-type resin film by which the dichroic dye was adsorption-oriented, and the transparent resin bonded together through the adhesive bond layer on at least one surface of the said polarizer, The adhesive bond layer is the following. It is providing the polarizing plate formed from the photocurable adhesive composition containing each component (A)-(D) of this.

(A) 100 parts by weight of the cationically polymerizable compound,

(B) 1 to 10 parts by weight of the photo cationic polymerization initiator,

(C) 0.1 to 2 parts by weight of a photosensitizer exhibiting maximum absorption in light of a wavelength longer than 380 nm, and

(D) 0.1 to 10 parts by weight of naphthalene-based photosensitization aid represented by the following formula (I).

<Formula I>

In the formula, R ¹ and R ² each independently represent an alkyl group having 1 to 6 carbon atoms.

In said polarizing plate, it is preferable that the cationically polymerizable compound (A) which comprises a photocurable adhesive composition contains the epoxy resin which does not contain an aromatic ring.

Moreover, in these polarizing plates, it is preferable that the photosensitizer (C) which comprises a photocurable adhesive composition is an anthracene type compound represented by following General formula (IV).

<Formula IV>

In formula, R <^5> and R <^6> respectively independently represents a C1-C6 alkyl group or a C2-C12 alkoxyalkyl group, and R <^7> represents a hydrogen atom or a C1-C6 alkyl group.

In any one of the said polarizing plates, it is advantageous that the quantity of the photosensitizer (C) is small in a photocurable adhesive composition in the range in which the adhesive force of a polarizer and a protective film is appropriately maintained from a viewpoint of maintaining neutral gray. Therefore, it is preferable to make the amount of a photosensitizer (C) into 0.1-0.5 weight part with respect to 100 weight part of cationically polymerizable compounds (A).

Also in any one of said polarizing plates, the aspect which comprises the protective film joined to at least one surface of a polarizer, for example from acetyl cellulose type resin can be taken. In addition, the protective film bonded to at least one surface of the polarizer may be formed of a resin having low moisture permeability, such as amorphous polyolefin resin, polyester resin, acrylic resin, polycarbonate resin, or chain polyolefin resin. have. A protective film made of acetylcellulose resin is bonded to one surface of the polarizer via the adhesive layer, and the same adhesive layer is placed on the other surface of the polarizer to form amorphous polyolefin resin, polyester resin, and acrylic resin. The aspect which joins the protective film which consists of transparent resins with low moisture permeability like resin, polycarbonate resin, and linear polyolefin resin is also preferable.

These polarizing plates can maintain the orthogonal color in the neutral gray of a polarizer, and can be assumed that the a value and b value of orthogonal color are all in the range of -0.5 to +0.5.

Moreover, this invention also provides the laminated optical member which consists of a laminated body of any one of said polarizing plates and another optical layer. In this laminated optical member, the optical layer preferably includes a retardation plate.

The polarizing plate of this invention reduces the quantity of the photosensitizer which shows the maximum absorption to the light of wavelength longer than 380 nm in the photocurable adhesive composition which bonds a polarizer and a protective film, and mix | blends a predetermined quantity a naphthalene type photosensitizer While maintaining the adhesive strength between the polarizer and the protective film, neutral gray which is the color of the polarizer can be expressed. In addition, the polarizing plate of the present invention hardly changes the degree of polarization or the orthogonal color even when placed in a moist heat environment, and exhibits good moisture heat resistance. The laminated optical member which laminated | stacked the other optical layer on this polarizing plate also fully expresses the function as a polarizing plate, and is excellent in moisture heat resistance.

Hereinafter, the present invention will be described in detail. The polarizing plate of this invention is equipped with a polarizer and the protective film bonded together through the adhesive bond layer on at least one surface of this polarizer.

[Polarizer]

A polarizer is comprised from the polyvinyl alcohol-type resin film by which the dichroic dye was adsorption-oriented. Polyvinyl alcohol-type resin which comprises a polarizer is obtained by saponifying polyvinyl acetate type resin. As polyvinyl acetate type resin, the copolymer etc. of vinyl acetate and the other monomer copolymerizable with this besides the polyvinyl acetate which is a homopolymer of vinyl acetate are illustrated. As another monomer copolymerized with vinyl acetate, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, etc. are mentioned, for example. The saponification degree of polyvinyl alcohol-type resin is 85 to 100 mol% normally, Preferably it is the range of 98-100 mol%. The polyvinyl alcohol-based resin may be further modified. For example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually in the range of 1,000 to 10,000, preferably 1,500 to 5,000.

The polarizer is a step of uniaxially stretching such a polyvinyl alcohol-based resin film, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye, adsorbing the dichroic dye, and a polyvinyl alcohol-based resin on which the dichroic dye is adsorbed. It is prepared through a process of treating the film with an aqueous boric acid solution.

Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, this uniaxial stretching may be performed before boric acid treatment, or may be performed during boric acid treatment. Of course, it is also possible to uniaxially stretch in these several steps. In order to uniaxially stretch, you may extend | stretch to 1 axis between rolls from which a circumferential speed differs, and you may extend | stretch to 1 axis using a thermal roll. Moreover, it may be dry stretching which extends | stretches in air | atmosphere, and it may be wet extending | stretching which extends | stretches in the state swollen with a solvent. A draw ratio is about 4 to 8 times normally.

In order to dye a polyvinyl alcohol-type resin film with a dichroic dye, what is necessary is just to immerse a polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye, for example. As a dichroic dye, an iodine or a dichroic organic dye is used specifically ,.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is employ | adopted normally. The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 10 parts by weight per 100 parts by weight of water. The temperature of this aqueous solution is about 20-40 degreeC normally, and the immersion time (dyeing time) in this aqueous solution is about 30 to 300 second normally.

On the other hand, when using a dichroic organic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic organic dye is employ | adopted normally. 2, the content of the dichroic organic dye in the aqueous solution used is usually 100 parts by weight of water per 1 × 10 ^-3 to 1 × 10 ^-2 parts by weight. This aqueous solution may contain inorganic salts, such as sodium sulfate. The temperature of this aqueous solution is about 20-80 degreeC normally, and the immersion time (dyeing time) in this aqueous solution is about 30 to 300 second normally.

The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-type resin film in boric-acid aqueous solution. Content of boric acid in boric-acid aqueous solution is about 2-15 weight part normally per 100 weight part of water, Preferably it is about 5-12 weight part. When using iodine as a dichroic dye, it is preferable that this boric acid aqueous solution contains potassium iodide. Content of potassium iodide in boric-acid aqueous solution is about 2-20 weight part normally per 100 weight part of water, Preferably it is 5-15 weight part. Immersion time in boric-acid aqueous solution is about 100 to 1,200 second normally, Preferably it is about 150 to 600 second, More preferably, it is about 200 to 400 second. The temperature of boric-acid aqueous solution is 50 degreeC or more normally, Preferably it is 50-85 degreeC.

The polyvinyl alcohol-based resin film is usually washed with water after boric acid treatment. The water washing process is performed by immersing the polyvinyl alcohol-type resin film processed by boric acid in water, for example. After washing with water, a drying treatment is performed to obtain a polarizer. The temperature of water in a water washing process is about 5-40 degreeC normally, and immersion time is about 2 to 120 second normally. The drying process performed after that is normally performed using a hot air dryer or a far-infrared heater. Drying temperature is 40-100 degreeC normally. In addition, the time of a drying process is about 120 to 600 second normally.

Thus, the thickness of the polarizer which consists of a polyvinyl alcohol-type resin film obtained can be about 10-50 micrometers.

Adhesive Layer

The polarizer obtained in this way is a protective film consisting of a transparent resin bonded to at least one surface thereof through an adhesive layer to form a polarizing plate. In this invention, the photocurable adhesive composition containing each component of the following (A)-(D) is used as an adhesive agent which forms the adhesive bond layer for bonding a protective film to a polarizer.

(A) a cationically polymerizable compound,

(B) photo cationic polymerization initiator,

(C) a photosensitizer exhibiting maximum absorption in light of wavelengths longer than 380 nm, and

(D) The naphthalene type photosensitizer represented by the said Formula (I).

Cationic Polymerizable Compound

Although the cationically polymerizable compound (A) which is a main component of a photocurable adhesive composition and becomes a component which provides adhesive force by superposition | polymerization hardening may be a compound which hardens | cures by cation polymerization, especially the epoxy compound which has at least two epoxy groups in a molecule | numerator It is preferable to include. The epoxy compound is an aromatic epoxy compound having an aromatic ring in a molecule, an alicyclic epoxy compound having at least two epoxy groups in a molecule, and at least one of which is bonded to an alicyclic ring, and having no aromatic ring in the molecule, And an aliphatic epoxy compound in which one carbon atom of a ring containing two carbon atoms to bond (usually an oxirane ring) is bonded to another aliphatic carbon atom. It is preferable that especially the photocurable adhesive composition used for this invention has an epoxy resin which does not contain an aromatic ring, especially an alicyclic epoxy compound as a main component as a cationically polymerizable compound (A). When using the cationically polymerizable compound which has an alicyclic epoxy compound as a main component, the hardened | cured material with a high storage elastic modulus is provided, and a polarizer is hard to be broken in the polarizing plate with a protective film and a polarizer adhering through the hardened | cured material (adhesive layer). Lose.

As described above, the alicyclic epoxy compound has at least two epoxy groups in the molecule, at least one of which is bonded to the alicyclic ring. Here, the epoxy group bonded to the alicyclic ring means two bonds of the epoxy group (-O-), each of which is composed of two carbon atoms (usually adjacent carbon atoms), as shown in the following general formula (V). It means that it is directly coupled. In the following general formula (V), m represents the integer of 2-5.

(V)

The compound coupled to the (CH _{2) m} group is the removed form the other chemical structure one or a plurality of hydrogen atoms in the formula V, can be an aliphatic epoxy compound. Hydrogen constituting the alicyclic ring may be appropriately substituted with a linear alkyl group such as methyl group or ethyl group. Especially, the compound which has an epoxy cyclopentane ring [what is m = 3 in the said General formula (V)], and an epoxy cyclohexane ring [what is m = 4 in the said General formula (V)] is preferable.

Also in an alicyclic epoxy compound, since it is easy to acquire and the effect which raises the storage elastic modulus of hardened | cured material is large, the compound represented by any one of following (1)-(11) is more preferable.

(Wherein, R ¹ to R ²⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when R ¹ to R ²⁴ are alkyl groups, the positions bonded to the alicyclic ring are 1 to 6 positions. The alkyl group having 1 to 6 carbon atoms may be linear, may have a branch, or may have an alicyclic ring, and Y ⁸ may be an oxygen atom or an alkanediyl group having 1 to 20 carbon atoms. Y ¹ to Y ⁷ each independently represent a straight chain, may have a branch, or may represent an alkanediyl group having 1 to 20 carbon atoms which may have an alicyclic ring, and n, p, q and r are Each independently represent a number from 0 to 20)

Among the compounds represented by the above (1) to (11), the alicyclic diepoxy compound represented by the general formula (2) is preferable because it is easy to obtain. The alicyclic diepoxy compound of the formula (2) is composed of 3,4-epoxycyclohexylmethanol (wherein an alkyl group having 1 to 6 carbon atoms may be bonded to its cyclohexane ring), and 3,4-epoxycyclohexanecarboxylic acid ( An alkyl group having 1 to 6 carbon atoms may be bonded to the cyclohexane ring thereof. Specific examples thereof include the following compounds.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate [compound in which R ⁵ = R ⁶ = H, n = 0 in Formula (2)],

3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate [In the formula (2), R ⁵ = 6-methyl, R ⁶ = 6-methyl, n = 0 compound] and the like.

Moreover, it is effective to use together the epoxy resin which does not have an alicyclic epoxy group substantially to an alicyclic epoxy compound. When an alicyclic epoxy compound is used as a main component and the epoxy resin which does not have an alicyclic epoxy group is used together as a cationically polymerizable compound, adhesiveness of a polarizer and a protective film is maintained, maintaining the storage elastic modulus of hardened | cured material at a high value. I can raise it more. The epoxy resin which does not have an alicyclic epoxy group here is a compound in which one carbon atom of the ring (usually an oxirane ring) containing the epoxy group and the two carbon atoms which it couple | bonds in a molecule | numerator is couple | bonded with another aliphatic carbon atom. to be. As an example, polyglycidyl ether of polyhydric alcohol (phenol) can be mentioned. Especially, since it is easy to acquire and the effect which raises adhesiveness of a polarizer and a protective film is large, the diglycidyl ether compound represented by following General formula (12) is preferable.

(Wherein X is a direct bond, a methylene group, an alkylidene group having 1 to 4 carbon atoms, an alicyclic hydrocarbon group, O, S, SO ₂ , SS, SO, CO, OCO or three kinds represented by the following formulae: A substituent selected from the group consisting of substituents, wherein the alkylidene group may be substituted with a halogen atom)

Wherein R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group which may be substituted with a phenyl group or 1 to 10 carbon atoms. A cycloalkyl group having 3 to 10 carbon atoms which may be substituted by an alkyl group or an alkoxy group, R ²⁵ and R ²⁶ may be linked to each other to form a ring, and A and D may be each independently substituted with a halogen atom An alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms which may be substituted by a halogen atom, an arylalkyl group having 7 to 20 carbon atoms which may be substituted by a halogen atom, or a carbon atom which may be substituted by a halogen atom A heterocyclic group or a halogen atom of 2 to 20, wherein the methylene group in the alkyl group, aryl group, or arylalkyl group is interrupted by an unsaturated bond, -O- or -S- There may be, a represents a number of 0 to 4, d represents a number of 0 to 4)

As the diglycidyl ether compound of the formula (12), for example, bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S ; Polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinylphenol; Polyglycidyl ethers of aliphatic polyhydric alcohols; Polyglycidyl ethers of alkylene oxide adducts of aliphatic polyhydric alcohols; Diglycidyl ether of alkylene glycol, and the like, and among them, polyglycidyl ether of aliphatic polyhydric alcohol is preferable because it is easy to obtain.

As said aliphatic polyhydric alcohol, the thing in the range of C2-C20 can be illustrated, for example. More specifically, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol , 1,4-butanediol, neopentylglycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl -2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, Aliphatic diols such as 2-methyl-1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; Alicyclic diols such as cyclohexanedimethanol, cyclohexanediol, hydrogenated bisphenol A and hydrogenated bisphenol F; Trivalent or more polyols, such as trimethylol ethane, trimethylol propane, hexitols, pentitols, glycerin, polyglycerol, pentaerythritol, dipentaerythritol and tetramethylol propane.

When using together an alicyclic epoxy compound and the epoxy resin which does not have an alicyclic epoxy group together, the compounding ratio of both is 50 to 95 weight% of an alicyclic epoxy compound based on the quantity of the whole cationic polymerizable compound, and an alicyclic type It is preferable to make the epoxy resin which does not have an epoxy group substantially 5 weight% or more. By mix | blending an alicyclic epoxy compound 50 weight% or more in the whole cationically polymerizable compound, the storage elastic modulus in 80 degreeC of hardened | cured material will be 1,000 MPa or more, and the polarizing plate with a polarizer and a protective film adhered through such hardened | cured material (adhesive layer). In the polarizer, it becomes difficult to break. Moreover, adhesiveness of a polarizer and a protective film improves by mix | blending 5 weight% or more of the epoxy resin which does not have an alicyclic epoxy group substantially with respect to the whole cationically polymerizable compound. The amount of the epoxy resin having substantially no alicyclic epoxy group is allowed up to 50% by weight based on the total amount of the cationic polymerizable compound when the cationically polymerizable compound is a two-component system with the alicyclic epoxy compound. When too much, the storage elastic modulus of hardened | cured material will fall and a polarizer will break easily, It is preferable to set it as 45 weight% or less based on the quantity of the whole cationically polymerizable compound.

As a cationically polymerizable compound (A) which comprises a photocurable adhesive composition, when using together the alicyclic epoxy compound mentioned above and the epoxy resin which does not have an alicyclic epoxy group together, in the range which each becomes the quantity demonstrated above In addition to these, other cationically polymerizable compounds may be included. As another cationically polymerizable compound, epoxy compounds other than Formula (1)-Formula (12), an oxetane compound, etc. are mentioned.

In an epoxy compound other than general formula (1)-(12), an alicyclic epoxy compound which has an epoxy group couple | bonded with at least 1 alicyclic ring in molecule | numerators other than general formula (1)-general formula (11), and other than general formula (12) Aliphatic epoxy compounds which have an oxirane ring couple | bonded with an aliphatic carbon atom, the aromatic epoxy compound which has an aromatic ring and an epoxy group in a molecule | numerator, the hydrogenation epoxy compound in which the aromatic ring in an aromatic epoxy compound is hydrogenated, etc. are mentioned.

As an example of the alicyclic epoxy compound which has an epoxy group couple | bonded with at least 1 alicyclic ring in molecule | numerators other than Formula (1)-Formula (11), 4-vinyl cyclohexene diepoxide or 1,2: 8,9-diepoxy And diepoxides of vinylcyclohexenes such as limonene.

Examples of aliphatic epoxy compounds having an oxirane ring bonded to an aliphatic carbon atom other than the formula (12) include triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, diglycidyl ether of polyethylene glycol, and the like. have.

The aromatic epoxy compound having an aromatic ring and an epoxy group in the molecule may be a glycidyl ether of an aromatic polyhydroxy compound having at least two phenolic hydroxyl groups in the molecule, and specific examples thereof include diglycidyl ether of bisphenol A and bisphenol F. Diglycidyl ether, diglycidyl ether of bisphenol S, glycidyl ether of phenol novolak resin, and the like.

The hydrogenated epoxy compound in which the aromatic ring in the aromatic epoxy compound is hydrogenated selectively hydrogenates an aromatic polyhydroxy compound having at least two phenolic hydroxyl groups in a molecule which is a raw material of the aromatic epoxy compound under pressure in the presence of a catalyst. The hydrogenated polyhydroxy compound obtained by carrying out the reaction may be glycidyl ether. Specific examples thereof include diglycidyl ether of hydrogenated bisphenol A, diglycidyl ether of hydrogenated bisphenol F, and diglycile of hydrogenated bisphenol S. Cyl ether, and the like.

Among the epoxy compounds other than these general formulas (1) to (12), in the case of compounding a compound classified into an alicyclic epoxy compound defined above, the compound having an epoxy group bonded to an alicyclic ring is represented by the above general formulas (1) to (11). The sum with an alicyclic epoxy compound represented by) is used in the range which does not exceed 95 weight% based on the total amount of a cationically polymerizable compound.

Moreover, the oxetane compound which can be arbitrary cationically polymerizable compound is a compound which has a 4-membered ring ether (oxetanyl group) in a molecule | numerator, The following compounds are mentioned as the specific example.

3-ethyl-3-hydroxymethyloxetane,

1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene,

3-ethyl-3- (phenoxymethyl) oxetane,

Di [(3-ethyl-3-oxetanyl) methyl] ether,

3-ethyl-3- (2-ethylhexyloxymethyl) oxetane,

3-ethyl-3- (cyclohexyloxymethyl) oxetane,

Phenol novolac oxetane,

1,3-bis [(3-ethyloxetan-3-yl) methoxy] benzene,

Oxetanyl Silsesquioxane,

Oxetanyl silicates and the like.

By mix | blending an oxetane compound in the ratio of 30 weight% or less based on the quantity of the whole cationically polymerizable compound, the effect which improves sclerosis | hardenability may be anticipated compared with the case where only an epoxy compound is used as a cationically polymerizable compound. .

(Photo cationic polymerization initiator)

In this invention, since the above-mentioned cationically polymerizable compound is hardened by cationic polymerization by irradiation of an active energy ray, and an adhesive bond layer is formed, a photocationic polymerization initiator (B) is mix | blended with a photocurable adhesive composition. The photocationic polymerization initiator generates cationic species or Lewis acids by irradiation of active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of the cationic polymerizable compound (A). Since a photocationic polymerization initiator acts catalytically with light, it is excellent in storage stability and workability even if it mixes with a cationically polymerizable compound (A). As a compound which generate | occur | produces a cationic species and a Lewis acid by irradiation of an active energy ray, For example, aromatic diazonium salt; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-arene complexes; and the like.

As aromatic diazonium salt, the following compounds are mentioned, for example.

Benzenediazonium hexafluoroantimonate,

Benzenediazonium hexafluorophosphate,

Benzenediazonium hexafluoroborate and the like.

As aromatic iodonium salt, the following compounds are mentioned, for example.

Diphenyl iodonium tetrakis (pentafluorophenyl) borate,

Diphenyl iodonium hexafluorophosphate,

Diphenyl iodonium hexafluoroantimonate,

Di (4-nonylphenyl) iodonium hexafluorophosphate and the like.

As an aromatic sulfonium salt, the following compounds are mentioned, for example.

Triphenylsulfonium hexafluorophosphate,

Triphenylsulfonium hexafluoroantimonate,

Triphenylsulfonium tetrakis (pentafluorophenyl) borate,

4,4'-bis [diphenylsulfonio] diphenylsulfide bishexafluorophosphate,

4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate,

4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluorophosphate,

7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,

7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,

4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate,

4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate,

4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like.

As an iron-arene complex, the following compounds are mentioned, for example.

Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,

Cumene-cyclopentadienyl iron (II) hexafluorophosphate,

Xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide and the like.

These photocationic polymerization initiators may be used independently, respectively, or may mix and use 2 or more types. Among these, aromatic sulfonium salts are particularly preferably used because they have excellent ultraviolet absorbing properties even in the wavelength region around 300 nm, and can provide a cured product having excellent mechanical strength and adhesive strength.

The compounding quantity of a photocationic polymerization initiator (B) shall be 1-10 weight part with respect to 100 weight part of whole cationic polymerizable compounds (A). By mix | blending 1 weight part or more of photocationic polymerization initiators per 100 weight part of cationically polymerizable compounds (A), a cationically polymerizable compound (A) can be fully hardened and a high mechanical strength and adhesive strength are provided to the polarizing plate obtained. On the other hand, when the amount thereof increases, the hygroscopicity of the cured product may increase due to an increase in the ionic substance in the cured product, and the durability of the polarizing plate may be lowered. Therefore, the amount of the photocationic polymerization initiator (B) is a cationically polymerizable compound ( A) 10 parts by weight or less per 100 parts by weight. It is preferable to make the compounding quantity of a photocationic polymerization initiator (B) into 2 weight part or more per 100 weight part of cationically polymerizable compounds (A), and also to be 6 weight part or less.

(Sensitizer)

The photocurable adhesive composition used for this invention is the light which shows the maximum absorption to the light of wavelength longer than 380 nm in addition to the cationically polymerizable compound (A) and photocationic polymerization initiator (B) which contain the above epoxy compounds. It contains a sensitizer (C). The photocationic polymerization initiator (B) exhibits maximum absorption at a wavelength near or shorter than 300 nm, generates cationic species or Lewis acids in response to light at a wavelength in the vicinity thereof, and generates a cation of the cationic polymerizable compound (A). Although the polymerization is initiated, a photosensitizer (C) exhibiting maximum absorption is blended with light having a wavelength longer than 380 nm so as to respond to light having a longer wavelength than that. As such a photosensitizer (C), the anthracene type compound represented by the said general formula (IV) is used advantageously. As specific examples of the anthracene-based compound represented by the formula (IV), the following compounds may be mentioned.

9,10-dimethoxyanthracene,

9,10-diethoxyanthracene,

9,10-dipropoxyanthracene,

9,10-diisopropoxyanthracene,

9,10-dibutoxyanthracene,

9,10-dipentyloxyanthracene,

9,10-dihexyloxyanthracene,

9,10-bis (2-methoxyethoxy) anthracene,

9,10-bis (2-ethoxyethoxy) anthracene,

9,10-bis (2-butoxyethoxy) anthracene,

9,10-bis (3-butoxypropoxy) anthracene,

2-methyl or 2-ethyl-9,10-dimethoxyanthracene,

2-methyl or 2-ethyl-9,10-diethoxyanthracene,

2-methyl or 2-ethyl-9,10-dipropoxycanthracene,

2-methyl or 2-ethyl-9,10-diisopropoxycanthracene,

2-methyl or 2-ethyl-9,10-dibutoxyanthracene,

2-methyl or 2-ethyl-9,10-dipentyloxyanthracene,

2-methyl or 2-ethyl-9,10-dihexyloxyanthracene and the like.

By mix | blending the photosensitizer (C) as mentioned above with a photocurable adhesive composition, the hardenability of an adhesive composition improves compared with the case where it is not mix | blended. Such an effect is expressed by making the compounding quantity of the photosensitizer (C) into 0.1 weight part or more with respect to 100 weight part of the cationically polymerizable compound (A) which comprises a photocurable adhesive composition. On the other hand, when the compounding quantity of a photosensitizer (C) increases, problems, such as precipitation at the time of low temperature storage, generate | occur | produce, and the quantity shall be 2 weight part or less with respect to 100 weight part of cationically polymerizable compounds (A). From the viewpoint of maintaining the neutral gray of the polarizing plate, it is advantageous to reduce the blending amount of the photosensitizer (C) in a range in which the adhesion between the polarizer and the protective film is appropriately maintained, for example, 100 wt% of the cationically polymerizable compound (A). It is preferable to make the quantity of a photosensitizer (C) into 0.1-0.5 weight part and 0.1-0.3 weight part with respect to a part.

(Photosensitization supplement)

The photocurable adhesive composition used for this invention is represented by the said general formula (I) in addition to the cationically polymerizable compound (A), the photocationic polymerization initiator (B), and the photosensitizer (C) containing the above-mentioned epoxy compound. It contains naphthalene type photosensitization adjuvant (D). In the general formula (I), R ¹ and R ² are each an alkyl group having 1 to 6 carbon atoms. As specific examples of the naphthalene-based light sensitizing aid (D), the following compounds may be mentioned.

1,4-dimethoxynaphthalene,

1-ethoxy-4-methoxynaphthalene,

1,4-diethoxynaphthalene,

1,4-dipropoxynaphthalene,

1,4-dibutoxynaphthalene etc.

By mix | blending a naphthalene type photosensitization adjuvant (D) with a photocurable adhesive composition, the hardenability of an adhesive composition improves compared with the case where it is not mix | blended. Such an effect is expressed by making the compounding quantity of a naphthalene type photosensitivity auxiliary agent (D) into 100 weight part of cationically polymerizable compounds (A) which comprise a photocurable adhesive composition to 0.1 weight part or more. On the other hand, when the compounding quantity of a naphthalene type photosensitivity auxiliary agent (D) becomes large, problems, such as precipitation at the time of low temperature storage, generate | occur | produce, Therefore, the quantity shall be 10 weight part or less with respect to 100 weight part of cationically polymerizable compounds (A). . The compounding quantity of a naphthalene type photosensitivity auxiliary agent (D) becomes like this. Preferably it is 5 weight part or less with respect to 100 weight part of cationically polymerizable compounds (A).

In addition, the photocurable adhesive composition of this invention can contain an additive component as another component which is an arbitrary component, unless the effect of this invention is impaired. As an additive component, in addition to the above-mentioned photocationic polymerization initiator and photosensitizer (C), the photosensitizer other than a photosensitizer (C), a thermal cationic polymerization initiator, a polyol, an ion trap agent, antioxidant, an optical stabilizer, A chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoamer, a leveling agent, a pigment, an organic solvent, etc. can be mix | blended.

When containing an additive component, it is preferable that the usage-amount of an additive component is 1000 weight part or less with respect to 100 weight part of above-mentioned cationically polymerizable compound (A). When the usage-amount is 1000 parts by weight or less, the cationically polymerizable compound (A), the photocationic polymerization initiator (B), the photosensitizer (C) and the photosensitizer (D) which are essential components of the photocurable adhesive composition of the present invention By combination, the effect of the improvement of storage stability, the prevention of discoloration, the improvement of a cure rate, and ensuring favorable adhesiveness can be exhibited favorably.

[Shield]

In this invention, a protective film is laminated | stacked on the polarizer which consists of a polyvinyl alcohol-type resin film demonstrated above through the photocurable adhesive composition demonstrated above, and a photocurable adhesive composition is hardened to make a polarizing plate. A protective film can be comprised from the acetyl cellulose-type resin film including the triacetyl cellulose which is conventionally used most widely as a protective film of a polarizing plate, and the resin film with a water vapor transmission rate lower than triacetyl cellulose. The water vapor permeability of triacetyl cellulose is usually about 400 g / m 2/24 hours.

In one preferable aspect, the protective film bonded to at least one side of the polarizer is composed of acetyl cellulose resin. In another preferred embodiment, the protective film bonded to at least one side of the polarizer is composed of a resin film having a water vapor transmission rate lower than that of triacetyl cellulose, for example, a resin film having a water vapor transmission rate of 300 g / m 2/24 hours or less. As resin which comprises such a resin film with low water vapor transmission rate, amorphous polyolefin resin, polyester resin, acrylic resin, polycarbonate resin, linear polyolefin resin, etc. are mentioned. In another preferred embodiment, a protective film made of an acetylcellulose resin is bonded to one surface of the polarizer via the adhesive layer, and the same adhesive layer is provided on the other surface of the polarizer to provide the same as described above. The protective film which consists of transparent resin with low water vapor transmission rate is bonded.

Acetyl cellulose resin is resin in which at least one part of the hydroxyl groups in a cellulose is acetate-esterified, a part is acetate-esterified, and the mixed ester in which one part is esterified by another acid may be sufficient. Specific examples of the acetyl cellulose resins include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like.

Amorphous polyolefin resins are polymers having polymerized units of cyclic olefins such as norbornene, tetracyclododecene (alias dimethanooctahydronaphthalene), or compounds in which substituents are bonded thereto, and chain olefins and / or cyclic olefins. Or a copolymer obtained by copolymerizing an aromatic vinyl compound. In the case of the homopolymer of cyclic olefin or the copolymer of 2 or more types of cyclic olefin, since a double bond remains by ring-opening polymerization, what was hydrogenated therein is generally used as amorphous polyolefin resin. Among them, thermoplastic norbornene-based resins are typical.

Polyester-based resin is a polymer obtained by condensation polymerization of dibasic acid and a dihydric alcohol, and polyethylene terephthalate is typical. The acrylic resin is a polymer containing methyl methacrylate as the main monomer, and in addition to the homopolymer of methyl methacrylate, a copolymer of methyl methacrylate and an acrylic acid ester such as methyl acrylate or an aromatic vinyl compound may be used. Polycarbonate resin is a polymer which has a carbonate bond (-O-CO-O-) in a principal chain, and what is obtained by condensation polymerization of bisphenol A and phosgene is typical. The linear polyolefin resin is a polymer containing a linear olefin such as ethylene or propylene as a main monomer, and may be a homopolymer or a copolymer. Especially, the homopolymer of propylene and the copolymer by which a small amount of ethylene is copolymerized in propylene are typical.

Such a protective film may have various surface treatment layers, such as a hard coat layer, an antireflection layer, an anti-glare layer, an antistatic layer, on the surface on the opposite side to the surface joined to a polarizer. The protective film can be made into about 5-150 micrometers in thickness, including the case where such a surface treatment layer is formed. The thickness thereof is preferably 10 µm or more, more preferably 120 µm or less, and more preferably 100 µm or less.

[Adhesion of Polarizer and Protective Film]

In adhesion | attachment of a polarizer and a protective film, the coating layer of the photocurable adhesive composition demonstrated above is formed in one or both of the bonding surfaces of a polarizer and a protective film, and a polarizer and a protective film are bonded together through the coating layer, and it forms in this way. The application layer of the uncured photocurable adhesive composition to be cured by irradiation of active energy rays, and the protective film is fixed on the polarizer. The coating layer of a photocurable adhesive composition may be formed in the bonding surface of a polarizer, and may be formed in the bonding surface of a protective film. Various coating methods, such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater, can be used for formation of an application layer. Moreover, the method of making an adhesive composition flexible can also be employ | adopted while supplying a polarizer and a protective film continuously so that the bonding surface of both may be inside. Since each coating system has an optimum viscosity range, it is also a useful technique to adjust the viscosity of a photocurable adhesive composition using a solvent. Although what melt | dissolves a photocurable adhesive composition favorably is used for the solvent for this without reducing the optical performance of a polarizer, there is no special limitation in the kind. For example, organic solvents, such as hydrocarbons represented by toluene and esters represented by ethyl acetate, can be used. The thickness of an adhesive bond layer is 20 micrometers or less normally, Preferably it is 10 micrometers or less, More preferably, it is 5 micrometers or less. When the adhesive layer becomes thick, the reaction rate of the adhesive composition is lowered, and the heat and moisture resistance of the polarizing plate tends to be deteriorated.

In adhering the polarizer and the protective film, one or both of the bonding surfaces has an easy adhesion treatment such as corona discharge treatment, plasma treatment, flame treatment, primer treatment, and anchor coating treatment before forming the coating layer of the adhesive composition. It may be practiced.

The light source used for irradiating an active energy ray to the application layer of a photocurable adhesive composition should just generate | occur | produce an ultraviolet-ray, an electron beam, X-rays, etc. In particular, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultrahigh pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps, metal halide lamps and the like which have a luminescence distribution at a wavelength of 400 nm or less are preferably used. Although the active energy ray irradiation intensity to a photocurable adhesive composition is determined for every target composition, it does not specifically limit, It is preferable that irradiation intensity of the wavelength range effective for activation of an initiator is 0.1-100 mW / cm <2>. If the intensity of light irradiation to the photocurable adhesive composition is less than 0.1 mW / cm 2, the reaction time becomes too long. If the photocurable adhesive composition exceeds 100 mW / cm 2, the photocurable adhesive is formed by heat generated from the lamp and heat generated during polymerization of the photocurable adhesive composition. There is a possibility of causing yellowing of the composition and deterioration of the polarizer. Although light irradiation time to a photocurable adhesive composition is controlled for every composition to harden, it is not specifically limited, either, It is preferable to set so that the accumulated light amount displayed as a product of irradiation intensity and irradiation time may be 10-5,000 mJ / cm <2>. . If the amount of accumulated light in the photocurable adhesive composition is less than 10 mJ / cm 2, there is a possibility that curing of the adhesive layer obtained due to the generation of active species derived from the initiator is insufficient, while the amount of accumulated light thereof exceeds 5,000 mJ / cm 2. Irradiation time becomes very long and becomes disadvantageous for productivity improvement.

When bonding a protective film to both surfaces of a polarizer, irradiation of an active energy ray can be performed on either protective film side, For example, when one protective film contains a ultraviolet absorber and the other protective film does not contain a ultraviolet absorber, Irradiation of an active energy ray from the protective film side which does not contain a ultraviolet absorber is preferable in order to make effective use of the irradiated active energy ray, and to raise hardening rate.

[Optical Characteristics of Polarizing Plate]

The polarizing plate of this invention reduces the quantity of the photosensitizer (C) which shows the maximum absorption to the light of wavelength longer than 380 nm mix | blended with a photocurable adhesive composition, and mix | blends predetermined amount a naphthalene type photosensitizer (D) While maintaining the adhesive strength between the polarizer and the protective film, the original color of the polarizer can be expressed as it is. For this reason, as long as it shows the neutral gray required by a polarizer, the neutral gray can be kept as it is, for example, it can make it the a value and the b value of orthogonal hue are all included in the range of -0.5 to +0.5.

Orthogonal color means the color of the light which permeate | transmits from the other surface, when the light is irradiated from one surface in the state which overlapped two polarizing plates so that each absorption axis may orthogonally cross. The color here is measured using the standard light C in a and b indicated by the Lab colorimeter. The Lab colorimeter is expressed by Hunter's brightness index L and colors a and b, as described in "5.5 Accelerated Weathering Test" of JIS K 5981: 2006. The values of L, a, and b are calculated by the following equation at three magnetic pole values X, Y, and Z defined in JIS Z 8722: 2009.

Moreover, even if exposed to the conditions of high temperature, high humidity, the polarizing plate of this invention is hard to deteriorate, and it is excellent in moisture heat resistance. For example, even after performing the wet heat test for 240 hours in a humid heat environment having a temperature of 60 ° C. and a relative humidity of 90%, the a value and the b value of the orthogonal color can be maintained in the above ranges.

[Laminated Optical Member]

The polarizing plate of this invention can be made into the laminated optical member by laminating | stacking the optical layers which have optical functions other than a polarizing plate. Typically, by laminating and adhering an optical layer through an adhesive or an adhesive to a protective film of a polarizing plate, it becomes a laminated optical member. In addition, for example, a protective film is provided by interposing a photocurable adhesive composition in accordance with this invention on one side of a polarizer, for example. The optical layer may be laminated and adhered to each other through the adhesive and the adhesive on the other side of the polarizer. In the latter case, when the photocurable adhesive composition prescribed | regulated by this invention is used as an adhesive agent for sticking a polarizer and an optical layer, the optical layer can also be a protective film prescribed | regulated by this invention simultaneously.

As an example of the optical layer laminated on the polarizing plate, the polarizing plate disposed on the back side of the liquid crystal cell includes a reflective layer, a semi-transmissive reflective layer, a light diffusing layer, a light collecting plate, laminated on the opposite side to the side facing the liquid crystal cell of the polarizing plate, Brightness enhancement films and the like. In addition, any of the polarizing plate arrange | positioned at the front surface side of a liquid crystal cell, and the polarizing plate arrange | positioned at the back side of a liquid crystal cell, there exists a phase difference plate etc. laminated | stacked on the side facing the liquid crystal cell of this polarizing plate.

The reflective layer, the semi-transmissive reflective layer, or the light diffusing layer is provided in order to be a reflective polarizing plate (optical member), a semi-transmissive reflective polarizing plate (optical member), or a diffusing polarizing plate (optical member), respectively. A reflective polarizing plate is used for a liquid crystal display device of the type which reflects and displays incident light from the viewer side, and can easily omit a liquid crystal display device because a light source such as a backlight can be omitted. The semi-transmissive polarizing plate is used for a liquid crystal display device of a type that is reflective in spots and is displayed in light from backlight in the dark. The optical member as a reflective polarizing plate can be formed by, for example, laying a foil or a vapor deposition film containing a metal such as aluminum on the protective film on the polarizer as a reflective layer. The optical member as a semi-transmissive polarizing plate can be formed by making the said reflection layer into a half mirror, or sticking the reflecting plate containing pearl pigment etc. and showing light transmittance to a polarizing plate. On the other hand, the optical member as a diffusion type polarizing plate uses various methods, such as a method of matting a protective film on a polarizing plate, the method of apply | coating microparticles-containing resin, the method of adhering the film containing microparticles | fine-particles, and to the surface, for example. It can form by forming a fine uneven structure.

In addition, the laminated optical member may be a polarizing plate for both reflection diffusion. The polarizing plate for both reflection and diffusion can be formed by, for example, providing a reflective layer on which the uneven structure is reflected on the fine uneven structure surface of the diffusing polarizing plate. A reflective layer having a fine concave-convex structure has the advantage of diffusing incident light by diffuse reflection, preventing directivity and blurring, and suppressing unevenness in light and dark. Moreover, the resin layer and film containing microparticles | fine-particles also have the advantage that they can spread | diffuse when incident light and its reflected light permeate | transmit a microparticles-containing layer, and can suppress a brightness-and-evenness nonuniformity. The reflective layer reflecting the surface fine concavo-convex structure can be formed by directly depositing a metal on the surface of the fine concavo-convex structure, for example, by a method such as vacuum deposition, ion plating, or deposition such as sputtering or plating. The fine particles to be blended to form the surface fine uneven structure include inorganic fine particles such as silica, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle diameter of 0.1 to 30 µm, Organic particulates such as crosslinked or uncrosslinked polymers.

The light collecting plate is used for the purpose of optical path control and the like, and may be a prism array sheet, a lens array sheet, a dot laying sheet, or the like.

The brightness enhancing film is used for the purpose of improving the brightness in a liquid crystal display device. Examples thereof include a reflective polarization separating sheet and a collet designed to generate anisotropy in reflectance by stacking a plurality of thin films having different refractive anisotropy. The circularly polarized light separating sheet which supported the oriented film of the steric liquid crystal polymer, or the oriented liquid crystal layer on the film base material, etc. are mentioned.

On the other hand, the retardation plate as the optical layer is used for the purpose of compensating the retardation by the liquid crystal cell. Examples thereof include a birefringent film containing a stretched film of various plastics, a film having an orientation fixed to a discotic liquid crystal or a nematic liquid crystal, a liquid crystal layer formed on the film substrate, and the like. When forming a liquid crystal layer on a film base material, cellulose resin films, such as a triacetyl cellulose, are used suitably as a film base material.

As a plastic which forms a birefringent film, For example, amorphous polyolefin resin, polycarbonate resin, acrylic resin, linear polyolefin resin like polypropylene, polyvinyl alcohol, polystyrene, polyarylate, polyamide Etc. can be mentioned. The stretched film may be processed by a suitable method such as uniaxial or biaxial. In addition, the retarder may be used in combination of two or more sheets for the purpose of controlling optical characteristics such as widening.

In a laminated optical member, what includes a retardation plate as an optical layer other than a polarizing plate is used suitably because it can perform optical compensation effectively, when applied to a liquid crystal display device. What is necessary is just to select the phase difference value (in-plane and thickness direction) of a phase difference plate according to the liquid crystal cell applied.

A laminated optical member can be made into the laminated body of two layers or three layers or more combining the polarizing plate and 1 or 2 layers or more selected according to the use purpose from the above-mentioned various optical layers. In that case, although the various optical layers which form a laminated optical member are integrated with a polarizing plate using an adhesive agent and an adhesive, there is no restriction | limiting in particular if the adhesive agent and adhesive agent used are favorable formation of an adhesive bond layer and an adhesive layer. It is preferable to use an adhesive (also called a pressure-sensitive adhesive) from the viewpoint of simplicity of bonding operation and prevention of occurrence of optical distortion. As an adhesive, what uses an acryl-type polymer, a silicone type polymer, polyester, a polyurethane, a polyether, etc. as a base polymer can be used. Among them, acrylic adhesives have excellent optical transparency, maintain proper wettability and cohesion, and have excellent adhesiveness with the substrate, and also have weather resistance and heat resistance, and peeling problems such as lifting and peeling under conditions of heating and humidification. It is preferable to select and use the thing which does not produce | generate. In the acrylic pressure sensitive adhesive, a functional group-containing acrylic monomer containing an alkyl ester of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group or a butyl group, and (meth) acrylic acid, (meth) acrylic acid hydroxyethyl, etc. An acrylic copolymer having a weight average molecular weight of 100,000 or more, which is blended so that the glass transition temperature is preferably 25 ° C. or less, more preferably 0 ° C. or less, is useful as the base polymer.

Formation of the pressure-sensitive adhesive layer on the polarizing plate, for example, by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a 10 to 40% by weight solution, and coating it directly on the polarizing plate, An adhesive layer is formed on a protective film, and this can be performed by the method of sticking on a polarizing plate. Although the thickness of an adhesive layer is determined according to the adhesive force etc., the range of about 1-50 micrometers is suitable.

The pressure-sensitive adhesive layer may be blended with a filler containing a glass fiber, glass beads, resin beads, metal powder or other inorganic powder, pigments, colorants, antioxidants, ultraviolet absorbers, and the like, as necessary. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex salt compounds and the like.

The laminated optical member can be disposed on one or both sides of the liquid crystal cell. The liquid crystal cell to be used is arbitrary, and for example, a liquid crystal display device can be formed using various liquid crystal cells such as an active matrix drive type represented by a thin film transistor type and a simple matrix drive type represented by a super twisted nematic type. Can be. An adhesive is usually used for adhesion of a laminated optical member and a liquid crystal cell.

<Examples>

Although an Example is given to the following and this invention is demonstrated to it further more concretely, this invention is not limited by these Examples. In the example,% and part which show content-usage-amount are a basis of weight unless it mentions specially. In addition, the cationically polymerizable compound, the photocationic polymerization initiator, the photosensitizer, and the photosensitization auxiliary agent used by the following examples are as follows, and are represented by each symbol below.

(A) Cationically polymerizable compound (abbreviated as "epoxy compound" in the table)

(a1) 3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate [Compound where R ⁵ = R ⁶ = H, n = 0 in the general formula (2)]

(a2) Celoxide 2081 (A cycloaliphatic epoxy resin manufactured by Daicel Chemical Industries, Ltd.) [Compound where R ⁵ = R ⁶ = H, Y ² = (CH ₂ ) ₅ , n = 1 in Formula (2).

(a3) Eporide GT-301 (A cycloaliphatic epoxy resin manufactured by Daicel Chemical Industries, Ltd.) [In Formula (3), R ⁷ = R ⁸ = R ⁹ = H, Y ³ = Y ⁴ = (CH ₂ ) ₅ , a compound wherein p = q = 1]

(a4) 1,4-butanediol diglycidyl ether [compound of Formula (12), wherein X = (CH ₂ ) ₄ ]

(a5) Adecarazine EP-4080E [Compound in the above formula (12), wherein X = 2,2-isobutylidene-biscyclohexyl]

(a6) A compound represented by the following formula (13)

(B) photo cationic polymerization initiator (abbreviated as "initiator" in the table)

(b1) triarylsulfonium hexafluorophosphate

(C) photosensitizers

(c1) 9,10-dibutoxyanthracene (in formula (IV), R ⁵ = R ⁶ = butyl, R ⁷ = H compound, maximum absorption at wavelength 382 nm)

(D) Light sensitizers (abbreviated as "sensitizers" in the table)

(d1) 1,4-diethoxynaphthalene [the compound of Formula (I) wherein R ¹ = R ² = ethyl]

(d2) 1-naphthol

[Reference Example] (Preparation of polyethylene terephthalate film having an antiglare layer)

Next, each component was melt | dissolved in ethyl acetate at 60% of solid content concentration, and the ultraviolet curable resin composition which provides the refractive index of 1.53 after hardening was prepared.

Pentaerythritol triacrylate 60 parts

40 parts of polyfunctional urethane acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate)

Next, with respect to 100 parts of solid content of this ultraviolet curable resin composition, 2 parts of porous silica particles [brand name "Sirisia", the product made by Fuji Silysia Chemical Co., Ltd.], and 2,4,6-trimethyl which are a photoinitiator are mentioned. 5 parts of benzoyldiphenyl phosphine oxide (brand name "Lucirine TPO", BASF Corporation make) was added, and the coating liquid was prepared.

This coating liquid was apply | coated on the biaxially stretched polyethylene terephthalate film (38 micrometers in thickness), the ultraviolet curable resin composition layer was formed, and it dried for 3 minutes in the dryer set to 80 degreeC. After drying, the film from the ultraviolet curable resin composition layer side of the film is irradiated with light from a high-pressure mercury lamp having an intensity of 20 mW / cm 2 so as to be 300 mJ / cm 2 in the amount of h-line converted light, the ultraviolet curable resin composition layer is cured, and unevenness is applied to the surface. The anti-glare film which has a haze value of 10% was obtained including the laminated body of the anti-glare layer (curing resin) to have and a biaxially stretched polyethylene terephthalate film. In addition, haze value was measured using the haze transmittance meter "HM-150" (Murakami Shikisai Gijutsu Co., Ltd. make).

[Examples 1 to 26 and Comparative Examples 1 to 13]

(1) Preparation of Photocurable Adhesive Composition

After mixing each component by the mixing | blending ratio (unit is part) shown in following Table 1, it defoamed and manufactured the photocurable adhesive liquid. In addition, the photocationic polymerization initiator (b1) was mix | blended as a 50% propylene carbonate solution, and is shown by Table 1 by the solid content thereof.

(2) Preparation of the polarizing plate

Corona discharge treatment is given to the surface of the 80-micrometer-thick triacetyl cellulose film containing a ultraviolet absorber (brand name "Fuji Tak", Fujifilm Co., Ltd. product), and it uses the bar coater on the corona discharge treatment surface as mentioned above. Each prepared adhesive liquid was coated so that the film thickness after hardening might be set to about 3 micrometers. The polyvinyl alcohol-iodine type polarizer was bonded to the adhesive bond layer. In addition, the corona discharge treatment is given to the bonding surface (surface on the opposite side to the anti-glare layer side) of the biaxially stretched polyethylene terephthalate film (43 micrometers in thickness) which has the anti-glare layer produced by the reference example, and the said corona discharge treatment surface was mentioned above. The same adhesive liquid as was coated with a bar coater so that the film thickness after curing was about 3 µm. The triacetyl cellulose film produced above was bonded to this adhesive bond layer, and the polarizer side of the polarizer bonded to one side was bonded, and the laminated body was produced. From the biaxially stretched polyethylene terephthalate film side which has an anti-glare layer of this laminated body, the accumulated light amount is 750 mJ / using the ultraviolet irradiation device (the lamp uses "D valve" by a fusion UV system company) with a belt conveyor. The adhesive was cured by irradiating ultraviolet rays so as to be cm 2. In this way, the polarizing plate in which the protective film was bonded to both surfaces of the polarizer was produced.

(3) evaluation of optical properties of the polarizing plate

The polarizing plate produced in the above (2) was cut into a size of 30 mm x 30 mm, and the orthogonal transmittance, polarization degree, a value and b value of the orthogonal color ("orthogonal a" and "orthogonal b" in the table, respectively). Abbreviation). For the measurement, an ultraviolet-visible spectrophotometer manufactured by Shimadzu Seisakusho Co., Ltd., "UV-2450", which was set with an optional accessory "film holder with polarizer", was used in the wavelength range of 380 nm to 780 nm. The transmission spectra of the polarizing plate in the transmission axis direction and the absorption axis direction are obtained, and the software "UV-Probe" attached to the spectrophotometer determines the orthogonal transmittance, polarization degree and orthogonal color at wavelengths of 410 nm, 550 nm and 650 nm. Value and b value were calculated. The results are shown in Table 2 below with the variation of the adhesive composition in Table 1 (amount of the photosensitizer and the photosensitizer).

(4) Evaluation of durability of polarizing plate under moist heat

The polarizing plate produced in the above (2) was cut into a size of 30 mm x 30 mm, and a wet heat test was performed for 240 hours in a humid heat environment having a temperature of 60 ° C. and a relative humidity of 90%, and the polarization degree and orthogonality of the polarizing plate after the test were measured. The a value and b value of the color were measured. The measurement was performed by the method similar to said (3). The results are shown in Table 2 together. In Table 2, the column "before test" is a value obtained with respect to the polarizing plate before performing a wet heat test, ie, immediately after preparation shown in said (3), and the column made "after test" is a polarizing plate after performing a wet heat test. The value obtained for.

As can be seen from Table 2, the polarizing plates obtained in Comparative Examples 1 to 3, 6, and 11 in which a large amount of anthracene-based photosensitizer (c1) was blended into the adhesive have a high orthogonal transmittance at a wavelength of 410 nm and are blue. At the same time that light leaked, the absolute values of the a-value and the b-value of the orthogonal color were high and were shifted from the neutral gray to the blue direction. In addition, the orthogonal color was greatly changed by the wet heat test. On the other hand, the polarizing plates obtained in Comparative Examples 4, 8, 9, and 13 in which the anthracene-based light sensitizer (c1) was not added to the adhesive showed good polarization degree immediately after preparation, no light leakage of blue color, and a neutral gray color. However, the moist heat resistance was bad, the polarization degree was less than 99% after the moist heat test, and the orthogonal color was also distorted from the neutral gray.

On the other hand, the polarizing plates obtained in Examples 1-26 using the adhesive agent which suppressed the compounding quantity of anthracene type photosensitizer (c1) in small quantity and mix | blended a predetermined amount with naphthalene type photosensitizer (d1) have a high polarization degree. And while providing a value and b value close to zero in orthogonal colors, it was confirmed that these values hardly changed before and after the wet heat test, and had good moisture heat resistance.

Claims (10)

The polarizing plate which consists of a polarizer which consists of a polyvinyl alcohol-type resin film by which the dichroic dye was adsorbed, and the protective film which consists of transparent resin bonded together through the adhesive bond layer on at least one surface of the said polarizer, The said adhesive bond layer is
(A) 100 parts by weight of the cationically polymerizable compound,
(B) 1 to 10 parts by weight of the photo cationic polymerization initiator,
(C) 0.1 to 2 parts by weight of a photosensitizer exhibiting maximum absorption in light of a wavelength longer than 380 nm and
(D) 0.1 to 10 parts by weight of naphthalene-based photosensitizing aid represented by the following formula (I)
The polarizing plate formed from the photocurable adhesive composition containing.
<Formula I>

(Wherein R ¹ and R ² each independently represent an alkyl group having 1 to 6 carbon atoms) The polarizing plate of Claim 1 whose said cationically polymerizable compound (A) is an epoxy resin which does not contain an aromatic ring. The polarizing plate according to claim 1, wherein the photosensitizer (C) is an anthracene-based compound represented by the following general formula (IV).
<Formula IV>

(Wherein R ⁵ and R ⁶ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms, and R ⁷ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) The polarizing plate of Claim 1 in which the said photocurable adhesive composition contains 0.1-0.5 weight part of said photosensitizers (C) with respect to 100 weight part of said cationically polymerizable compounds (A). The polarizing plate according to claim 1, wherein the protective film bonded to at least one side of the polarizer is made of an acetyl cellulose resin. The protective film bonded to at least one side of the polarizer is a transparent resin selected from the group consisting of amorphous polyolefin resins, polyester resins, acrylic resins, polycarbonate resins and chain polyolefin resins. Polarizing plate made up. The protective film made of acetylcellulose resin bonded to one surface of the polarizer via the adhesive layer, and the amorphous polyolefin resin and polyester bonded to the other surface of the polarizer via the adhesive layer. The polarizing plate provided with the protective film which consists of transparent resin chosen from the group which consists of resin, acrylic resin, polycarbonate resin, and linear polyolefin resin. The polarizing plate according to claim 1, wherein both the a value and the b value of the orthogonal color are in the range of -0.5 to +0.5. The laminated optical member which consists of a laminated body of the polarizing plate of Claim 1, and another optical layer. The laminated optical member of claim 9, wherein the optical layer comprises a retardation plate.