KR101526032B1 - Composition for optical elemet - Google Patents

Abstract

The present invention relates to a composition for attaching an optical element, a point adhesive for an optical element, an optical element, a polarizing plate, and a liquid crystal display. Exemplary compositions of the present invention are used in the attachment of optical elements and are applied in the form of a tackifier in use and can be cured to produce higher bond strength. The composition can be cured to exhibit a high modulus of elasticity and a peeling force at the same time, and thus it is possible to provide an optical element excellent in durability and dimensional stability even when it is left under severe conditions. Further, the composition does not require an additional aging process after curing in the curing process, suppresses the change with time, and is optically transparent.

Description

TECHNICAL FIELD [0001] The present invention relates to a composition for an optical element,

The present invention relates to a composition for an optical element, a point adhesive for attaching an optical element, an optical element, a polarizing plate, and a liquid crystal display device.

A display device such as a liquid crystal display (hereinafter referred to as "LCD") may include a polarizer, a polarizer protective film, a retardation plate, a reflective layer, a transflective reflective layer, an antireflection layer, a light diffusion layer, And the like. A pressure sensitive adhesive or an adhesive may be used in the course of manufacturing a laminate by attaching the optical elements to each other or applying the optical element or the laminate to a display device.

BACKGROUND OF THE INVENTION Pressure sensitive adhesives ("PSA") are used in a variety of applications because of their many useful properties, including the ability to repeatedly peel and adhere. However, the pressure-sensitive adhesive does not exhibit sufficient adhesive strength to some extent on some substrates when exposed to a particularly high temperature or humidity, and is therefore not suitable for permanent attachment of the device.

If a permanent bond or high bond strength is required, an adhesive may be used. However, typically, the adhesive is not provided in a form that is easy to apply, such as in the form of a pressure-sensitive adhesive or a tape, but is typically provided in a liquid form or the like.

As a form capable of achieving both strength and ease of application, so-called hybrid compositions or point-adhesive compositions are known. Such a composition is a composition which is applied in the form of a pressure-sensitive adhesive and which can then produce a higher structural or semi-structural bond strength.

An object of the present invention is to provide a composition for an optical element, a point adhesive for an optical element, an optical element, a polarizing plate, and a liquid crystal display.

An exemplary composition of the present invention is a pressure-sensitive adhesive resin comprising a monomer of the following formula (1) as a polymerization unit; An alicyclic epoxy compound, an aliphatic epoxy compound, and a cellulose ester compound.

[Chemical Formula 1]

Wherein R is hydrogen or an alkyl group, A is an alkylene group or an alkylidene group, K is an alkyl group or an aryl group, and n is a number of 1 to 50.

The alicyclic epoxy compound, the aliphatic epoxy compound and the cellulose acetate compound in the composition are contained in an amount of 1 part by weight to 30 parts by weight, 1 part by weight to 25 parts by weight and 1 part by weight to 60 parts by weight relative to 100 parts by weight of the adhesive resin, As shown in FIG. Unless specifically stated otherwise herein, the unit weight portion may mean the ratio of the weight between each component.

The composition can be used, for example, for an optical element, specifically for attaching an optical element. The attachment of an optical element may refer to a composition used for attaching two or more optical elements to each other to produce a laminate or attaching an optical element or a laminate thereof to a display device such as an LCD or the like. The range of the optical element may include a polarizer, a polarizer protective film, a retardation plate, a reflection layer, a transflective reflective layer, an antireflection layer, a light diffusion layer, a light collecting plate or a brightness enhancement film.

The composition may also be a so-called hybrid composition or a pressure-sensitive adhesive composition, which is applied in the form of a pressure-sensitive adhesive, and which can produce a high bonding strength through a curing process or the like at a necessary point in time.

The above-mentioned curing of the composition means a process of developing an adhesive property or an adhesive property to the composition by physical or chemical reaction or action of the component contained in the composition. The composition may be, for example, an active energy ray curable composition which is cured by irradiation with an active energy ray or a cationically curable composition which is cured by a cation curing reaction. The term " cationically curable composition " can refer to a composition that can be cured, for example, by cationic polymerization or cationic cure reaction induced by irradiation of active energy rays or application of heat. In one example, the cationic polymerization or curing reaction can be induced by irradiation of an active energy beam. Such a composition is excellent in storage stability and excellent in resistance to deterioration and discoloration. Further, the curing rate can be maintained sufficiently fast, and a high peeling force can be exhibited after curing. Further, the composition as described above can prevent deformation of the adherend due to shrinkage or the like during the curing process. The term " active energy ray " as used herein includes, but is not limited to, microwaves, IR, ultraviolet, X-rays and gamma rays as well as alpha-particle beams, a particle beam such as a proton beam, a neutron beam, and an electron beam, and may be ultraviolet rays or electron beams.

The adhesive resin can be used without particular limitation, as long as it exhibits properties as a pressure-sensitive adhesive resin and contains the monomer of the above formula (1) as a polymerization unit. In the present specification, the predetermined component is contained as a polymerization unit in the resin. That is, in the polymerization or copolymerization of the resin, the predetermined component is used as a monomer component or the like, and the predetermined component is polymerized or copolymerized to form a skeleton As shown in Fig.

The monomer of the formula (1) can be used even when the composition or the cured product thereof is exposed to a condition of high temperature or high humidity or a change of environmental conditions such as temperature or humidity (hereinafter sometimes referred to as "harsh conditions") Excellent optical properties, for example, transparency can be maintained.

Wherein R is hydrogen or an alkyl group, A is an alkylene group or an alkylidene group, K is an alkyl group or an aryl group, and n is a number of 1 to 50.

In the present specification, unless otherwise specified, the alkyl group includes straight, branched or cyclic alkyl groups of 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, Means that the alkyl group is optionally substituted by one or more substituents. In the present specification, the cyclic structure may include a single ring, a heterocyclic ring or a spiro ring.

The alkylene group or the alkylidene group in the present specification is a straight chain, branched or cyclic alkylene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms, Or a cyclic alkylene group or an alkylidene group, and the alkylene group or the alkylidene group may be optionally substituted by one or more substituents.

Unless otherwise specified, the term aryl group in the present specification is a monovalent residue derived from a compound or derivative thereof containing a structure in which benzene or two or more benzenes are bonded to each other or condensed, To 24, and a substituted or unsubstituted aryl group having 6 to 18 carbon atoms or 6 to 12 carbon atoms.

Examples of the substituent of the substituted alkyl group, alkylene group, alkylidene group or aryl group in the above include a monovalent hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group or an aryl group, a halogen, a hydroxyl group, an epoxy group, an alkoxy group, , A methacryloyl group or a thiol group, but the present invention is not limited thereto.

In formula (1), A is preferably an alkylene group having 1 to 4 carbon atoms or an alkylidene group having 1 to 4 carbon atoms, and in other examples, it may be an alkylene group having 1 to 4 carbon atoms.

In the above formula (1), K is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms.

In Formula 1, n may be 1 to 40, 1 to 30, 1 to 20, 1 to 20, 1 to 10, or 1 to 5. When n is 2 or more in the general formula (1), the carbon number of A in the repeating unit A-O may be the same or different for each repeating unit.

In one example, the pressure-sensitive adhesive resin may be a non-crosslinkable pressure-sensitive adhesive resin. As used herein, the term " non-crosslinkable adhesive resin " may refer to a resin that does not form a crosslinked structure in the final cured composition. Therefore, the non-crosslinkable pressure-sensitive adhesive resin is preferably a crosslinkable pressure-sensitive adhesive resin which is capable of realizing a crosslinked structure by reaction with a polyfunctional crosslinking agent such as a hydroxyl group or a carboxyl group, or capable of inducing self crosslinking of an adhesive resin such as polyfunctional acrylate, It does not contain a functional group known as a so-called crosslinkable functional group, or it can be contained only in a very small amount. In a preferred example, the pressure-sensitive adhesive resin may be a non-crosslinkable pressure-sensitive adhesive resin not containing the crosslinkable functional group.

An exemplary adhesive resin may be a polymer comprising a (meth) acrylic acid ester monomer and the monomer of the above formula (1) as polymerized units. The adhesive resin may include 40 to 90 parts by weight of the (meth) acrylic acid ester monomer and 10 to 70 parts by weight of the monomer of the formula (1). In a preferred example, the pressure-sensitive adhesive resin may include 50 to 80 parts by weight of a (meth) acrylic acid ester monomer and 20 to 50 parts by weight of the monomer of the formula (1) as polymerized units. By controlling the weight ratio of the monomers contained in the form of polymerized to the adhesive resin as described above, it is possible to obtain a composition exhibiting appropriate tackiness and optical properties.

As the (meth) acrylic acid ester monomer, for example, alkyl (meth) acrylate can be used. In consideration of cohesion, glass transition temperature and tackiness, a linear, branched or cyclic alkyl group having 1 to 14 carbon atoms (Meth) acrylate can be used. Examples of such monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, (Meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, sec-butyl (Meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, and tetradecyl (meth) acrylate. One or more of these monomers may be used.

The pressure-sensitive adhesive resin may further comprise any known copolymerizable monomers used in the production of the pressure-sensitive adhesive resin in addition to the above monomers. However, if the pressure-sensitive adhesive resin is a non-crosslinkable resin, it is preferable not to use a comonomer that provides a pressure-sensitive adhesive resin with a crosslinkable functional group.

The pressure-sensitive adhesive resin can be produced by applying a mixture of monomers containing the aforementioned monomers to a conventional polymerization method such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization or emulsion polymerization.

The adhesive resin is, for example, a weight average molecular weight _{(M w: Weight Average Molecular Weight} ) is more than 300,000, may be equal to or greater than 400,000 or more than 500,000. In the present specification, the weight average molecular weight is a value converted to a standard polystyrene measured by GPC (Gel Permeation Chromatograph). In this specification, unless otherwise specified, the term "molecular weight" means "weight average molecular weight". When the molecular weight of the polymer is 300,000 or more, excellent durability can be ensured under severe conditions. The upper limit of the molecular weight is not particularly limited and can be controlled within a range of not more than 3 million, not more than 2.5 million, or not more than 2 million, for example, in consideration of durability and coating property of the composition.

The composition includes an alicyclic epoxy compound. In the present specification, the term alicyclic epoxy compound means a compound containing at least one alicyclic epoxy group, wherein the alicyclic epoxy group has an aliphatic saturated hydrocarbon ring, and the two carbon atoms constituting the ring also constitute an epoxy group Functional group. Preferably, the alicyclic epoxy compound may be a compound in which all epoxy groups are alicyclic epoxy groups.

As the alicyclic epoxy compound, for example, epoxycyclohexylmethyl epoxycyclohexanecarboxylate compound; Epoxycyclohexanecarboxylate compounds of alkanediol; An epoxycyclohexylmethyl ester compound of dicarboxylic acid; Epoxycyclohexyl methyl ether compounds of polyethylene glycol; Epoxycyclohexyl methyl ether compounds of alkanediol; Diepoxy trispyrene compounds; Diepoxy monospiro compounds; Vinylcyclohexene diepoxide compounds; An epoxycyclopentyl ether compound or a diepoxy tricyclodecane compound. Examples of the alicyclic epoxy compound include compounds represented by the following formulas (2) to (11), respectively.

(2)

In Formula 2, R ₁ and R ₂ each independently represent hydrogen or an alkyl group.

(3)

In the above formula (3), R ₃ and R ₄ each independently represent hydrogen or an alkyl group, and n represents an integer of 2 to 20.

[Chemical Formula 4]

In the formula (4), R ₅ and R ₆ each independently represent hydrogen or an alkyl group, and p represents an integer of 2 to 20.

[Chemical Formula 5]

In the general formula (5), R ₇ and R ₈ each independently represent hydrogen or an alkyl group, and q represents an integer of 2 to 20.

[Chemical Formula 6]

In the above formula (6), R ₉ and R ₁₀ each independently represents hydrogen or an alkyl group, and r represents an integer of 2 to 20.

(7)

In the formula (7), R ₁₁ and R ₁₂ each independently represent hydrogen or an alkyl group.

[Chemical Formula 8]

In Formula 8, R ₁₃ and R ₁₄ each independently represent hydrogen or an alkyl group.

[Chemical Formula 9]

In Formula 9, R ₁₅ represents hydrogen or an alkyl group.

[Chemical formula 10]

In the above formula (10), R ₁₆ and R ₁₇ each independently represent hydrogen or an alkyl group.

(11)

In Formula 11, R ₁₈ represents hydrogen or an alkyl group.

As the alicyclic epoxy compound, it is preferable to use an epoxycyclohexylmethyl epoxycyclohexanecarboxylate compound, an epoxycyclohexanecarboxylate compound of an alkanediol, an epoxycyclohexylmethyl ester compound of a dicarboxylic acid, or an epoxycyclohexylmethyl ether compound of an alkanediol Preferred is an esterified product of 7-oxabicyclo [4,1,0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4,1,0] hept- Wherein R < ₁ > and R < ₂ > are hydrogen; Ester of 4-methyl-7-oxabicyclo [4,1,0] heptane-3-carboxylic acid with (4-methyl-7-oxa-bicyclo [ Cargo (in the formula 3, R ₁ is 4-CH ₃ and R ₂ is 4-CH ₃ ); An esterified product of 7-oxabicyclo [4,1,0] heptane-3-carboxylic acid and 1,2-ethanediol (in the formula 4, R ₃ and R ₄ are hydrogen and n is 1); (7-oxabicyclo [4,1,0] hept-3-yl) methanol and adipic acid (compound of formula 5 wherein R ₅ and R ₆ are hydrogen and p is 2); (4-methyl-7-oxabicyclo [4,1,0] hept-3-yl) methanol and adipic acid (wherein R ₅ and R ₆ are 4-CH ₃ and p is 2); And ethers of (7-oxabicyclo [4,1,0] hept-3-yl) methanol and 1,2-ethanediol in which R ₉ and R ₁₀ are hydrogen and r is 1 ), But the present invention is not limited thereto.

The composition may contain the alicyclic epoxy compound in an amount of 1 to 30 parts by weight, preferably 5 to 25 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the pressure- 20 parts by weight. If the weight ratio of the alicyclic epoxy compound is too low, the peeling force of the cured product may be deteriorated. If the weight ratio is too high, the processability and coating properties of the composition may deteriorate or the curing degree may become too high, Since there is a possibility of brittle, it is possible to adjust the appropriate content in consideration of this point.

As the aliphatic epoxy compound, an epoxy compound containing at least one aliphatic epoxy group other than an alicyclic epoxy group may be used. Examples of the aliphatic epoxy compound include polyglycidyl ethers of aliphatic polyhydric alcohols; Polyglycidyl ethers of alkylene oxide adducts of aliphatic polyhydric alcohols; Polyglycidyl ethers of polyester polyols of aliphatic polyhydric alcohols and aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of polyester polycarboxylic acids of aliphatic polyhydric alcohols and aliphatic polyvalent carboxylic acids; Dimers, oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate; Or an oligomer or polymer obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate and other vinyl monomers, and preferably an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof polyglycidyl Ethers may be used, but are not limited thereto.

Examples of the aliphatic polyhydric alcohols include, for example, aliphatic polyhydric alcohols having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl- Pentanediol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, Pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl- Aliphatic diols such as octanediol, 1,9-nonanediol, and 1,10-decanediol; Alicyclic diols such as cyclohexane dimethanol, cyclohexanediol, hydrogenated bisphenol A and hydrogenated bisphenol F; Trimethylol ethane, trimethylol propane, hexitol, pentitol, glycerin, polyglycerin, pentaerythritol, dipentaerythritol, tetramethylol propane and the like.

Examples of the alkylene oxides include alkylene oxides having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms and 1 to 4 carbon atoms such as ethylene oxide Seed, propylene oxide, or butylene oxide may be used.

Examples of the aliphatic polycarboxylic acid include aliphatic polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, , 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, 3,7-dimethyldecanedioic acid, Dicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1 , 4-cyclohexanedicarboxylic acid, 1,4-dicarboxylmethylene cyclohexane, 1,2,3-propanetricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2 , 3,4-cyclobutanetetracarboxylic acid, and the like, but are not limited thereto.

As the aliphatic epoxy compound, a compound having no alicyclic epoxy group and a compound containing three or more aliphatic epoxy groups other than an alicyclic epoxy group is preferably used because it has good curability and is excellent in weatherability and refractive index characteristics after curing Is preferable from the viewpoint of being excellent.

The composition may include 1 to 25 parts by weight, preferably 5 to 20 parts by weight, of the aliphatic epoxy compound relative to 100 parts by weight of the pressure-sensitive adhesive resin. When the aliphatic epoxy compound is contained in the above weight ratio, it is possible to provide a cured product excellent in adhesiveness, long-term adhesion, durability and optical transparency.

The composition also includes a cellulose ester compound. As the cellulose ester compound, for example, cellulose acetate alkylate can be used, wherein the alkylate has 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, Eight, or one to four. Examples of such compounds include, but are not limited to, cellulose acetate butyrate and / or cellulose acetate propionate.

The cellulose ester compound may be included in the composition in an amount of 1 part by weight to 60 parts by weight, or in an amount of 10 parts by weight to 50 parts by weight or 20 parts by weight to 40 parts by weight, based on 100 parts by weight of the adhesive resin. When the cellulose ester compound is contained in the above weight ratio, it is possible to provide a cured product having excellent adhesiveness, long-term adhesion and durability reliability.

The composition may further comprise a cationic initiator as an initiator for initiating the curing reaction. The cationic initiator can be used without any particular limitations as long as it can initiate the cationic reaction by application of heat or an active energy ray. For example, a cationic photoinitiator that initiates a cationic reaction by irradiation with an active energy ray may be used .

In one example, the cationic photoinitiator is an ionized cationic initiator of the onium salt or organometallic salt series or a nonionized cationic initiator such as an organosilane or latent sulfonic acid series or other non- Cationic photoinitiators can be used. As the initiator of the onium salt series, diaryliodonium salt, triarylsulfonium salt or aryldiazonium salt can be exemplified, and the initiation of the organometallic salt series Examples of the initiator of the organosilane series include o-nitrobenzyl triaryl silyl ether, triaryl silyl peroxide, and the like. Or acyl silane, and examples of the initiator of the latent sulfuric acid series include, but are not limited to, a -sulfonyloxy ketone or a-hydroxymethyl benzoin sulfonate and the like . As the cationic initiator, a mixture of an iodine-based initiator and a photosensitizer may be used.

As the cationic initiator, it is preferable to use an ionized cationic photoinitiator, more preferably an onium salt-based ionized cationic photoinitiator, more preferably an ionized cationic photoinitiator based on triarylsulfonium salt, It is not.

The composition may contain 1 to 60 parts by weight, preferably 1 to 40 parts by weight, more preferably 10 to 40 parts by weight, of the cationic initiator relative to 100 parts by weight of the epoxy compound. In the above, the weight ratio of the epoxy compound is the total ratio of the aliphatic and alicyclic epoxy compounds, and at such a ratio, an adhesive composition excellent in curing efficiency and physical properties after cured can be provided.

The above composition may further include a cationic polymerizable monomer, from the viewpoint of improving the adhesion after curing, if necessary.

As the cationic polymerizable monomer, an oxetane compound can be exemplified. The oxetane compound is a compound having a quaternary cyclic ether group in its molecular structure and specifically includes 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl (Methoxymethyl) benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [ Methyl) oxetane or phenol novolac oxetane, and the like. Examples of the oxetane compound include "Alon oxetane OXT-101", "Alon oxetane OXT-121", "Alon oxetane OXT-211", "Alon oxetane OXT-221" &Quot; Alon oxetane OXT-212 " and the like can be used.

The cationic polymerizable monomer may be used in an appropriate weight ratio in consideration of weatherability and curability of the composition.

The composition may further comprise a photosensitizer. Examples of the photosensitizer include anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds or photo-reducible pigments. The photosensitizer can be used, for example, in a proportion of 20 parts by weight or less based on 100 parts by weight of the cationic polymerizable component contained in the composition.

Specific photosensitizers include, for example, an anthracene compound represented by the following formula (12); Pyrene; Benzoin methyl ether, benzoin isopropyl ether, benzoin derivatives such as a, a-dimethoxy-a-phenylacetophenone; Benzophenone derivatives such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone and 4,4'-bis (diethylamino) benzophenone; Thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; Anthraquinone derivatives such as 2-chloro anthraquinone and 2-methyl anthraquinone; Acridone derivatives such as N-methyl acridone, N-butyl acridone; Other examples include a, a-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compound or halogen compound.

[Chemical Formula 12]

In the above formula (12), R ₁₉ and R ₂₀ each independently represent an alkyl group or an ether group, and R ₂₁ represents hydrogen or an alkyl group.

Examples of the alkyl group which may be present in R ₁₉ , R ₂₀ and R ₂₁ in the general formula (12) include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, A cyclohexyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a heptyl group, a 2-heptyl group, a 3-heptyl group, an isoheptyl group, an n-octyl group, an isooxyl group, A decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, or an octadecyl group.

Examples of the ether group which may be present in R ₁₉ and R ₂₀ include a 2-methoxyethyl group, a 2-ethoxyethyl group, a 2-butoxyethyl group, a 2-phenoxyethyl group, a 2- (2-methoxyethoxy) ethyl group, a 3-methoxypropyl group, a 3-butoxypropyl group, a 3-phenoxypropyl group, a 2-methoxy- , 2-methoxyethyl group, 2-ethoxyethyl group, 2-butoxyethyl group, 2-phenoxyethyl group and the like. The ether group in the formula (12) means a hydrocarbon group having at least one ether bond, as understood from the above examples, and includes an alkoxyalkyl group, an alkoxyalkoxyalkyl group or an aryloxyalkyl group.

As the photosensitizer, compounds in which R ₁₉ and R ₂₀ are alkyl groups having 1 to 4 carbon atoms and R ₂₁ is hydrogen or alkyl groups having 1 to 4 carbon atoms are preferably used in the formula (12).

The photosensitizer may be used in an appropriate weight ratio taking into account the desired addition effect.

The composition may further comprise a polyol compound. The polyol compound may react with the epoxy compound to form a polymer. As the polyol compound, it is preferable to use a compound which does not contain an acidic functional group in addition to the phenolic hydroxyl group, and a polyol compound, a polyester polyol compound, a polycaprolactone polyol compound and a compound having a phenolic hydroxyl group, which do not contain a functional group other than a hydroxyl group, A polyol compound or polycarbonate polyol, and the like can be exemplified, but are not limited thereto.

The polyol compound can be used in an appropriate weight ratio in consideration of the desired addition effect.

The composition may further include additives such as an ion trap agent, an antioxidant, a light stabilizer, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, a defoamer, can do.

The composition can, for example, provide a cured product which simultaneously exhibits a high modulus of elasticity and a high peel force.

In one example, the composition has a modulus of elasticity of 0.3 MPa or 0.4 MPa or more. The elastic modulus may be, for example, a storage modulus or a tensile modulus, and preferably a tensile modulus. Also, the elastic modulus may be an elastic modulus measured at room temperature. As used herein, the term ambient temperature refers to a natural, unheated or non-warmed temperature, for example, from 10 ° C to 40 ° C, from 20 ° C to 30 ° C, from about 20 ° C to about 23 ° C, Of the temperature.

The preferable upper limit of the modulus of elasticity may be, for example, 1 MPa, 0.8 MPa or 0.6.

In one example, the composition may have a peel force after curing of 1,500 gf / 25 mm or more or 2,000 gf / 25 mm or more. In the above, the peeling force is a peeling force against alkali-free glass, and may be a peeling force measured at a peeling speed of 300 mm / min at room temperature and a peeling angle of 180 degrees. The upper limit of the peeling force may be, for example, about 5,000 gf / 25 mm or about 4,000 gf / 25 mm.

An exemplary point adhesive for an optical element of the present invention may include a layer containing the above-described composition as it is, or containing the composition in a cured state. That is, an exemplary point adhesive for an optical element includes a pressure-sensitive adhesive resin containing the monomer of the above formula (1); A composition comprising an alicyclic epoxy compound, an aliphatic epoxy compound and a cellulose ester compound, or a layer containing the composition in a cured state. Each component of the composition may be included in the weight ratio described above. The point adhesive in the above may be applied in the form of a pressure-sensitive adhesive, and may mean a material whose state can be changed to exhibit a high bonding strength at a necessary point.

The specific kinds and ratios of the respective components contained in the composition are as described above, and the composition may further include additional components already described.

The method for forming the layer containing the composition or the cured product is not particularly limited and may be carried out by a method such as a bar coater, a spin coater, a gravure coater or an ink jet coater, Applying a coating liquid, and optionally curing the composition through irradiation of an active energy ray or the like.

The manner of curing the composition is not particularly limited. For example, a method of irradiating an active energy ray to initiate cationic polymerization and / or radical polymerization reaction of the composition can be used. The light source for irradiating the active energy ray is not particularly limited, but a light source capable of irradiating an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable, and a light source such as low pressure, medium pressure, high pressure or ultra high pressure mercury lamp, , A microwave-excited mercury lamp or a metal halide lamp, and the like.

The irradiation intensity of the active energy ray is determined depending on the composition of the composition and is not particularly limited, but it is preferable that the irradiation intensity in the wavelength range effective for activating the initiator is 0.1 mW / cm ² to 6,000 mW / cm ² . When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time is not excessively long, and when the irradiation intensity is 6000 mW / cm ² or less, the yellow radiation of the epoxy resin or the deterioration of the polarizer due to heat radiated from the light source and heat generated during curing of the composition is prevented can do. The irradiation time is controlled in accordance with the composition to be cured and is not particularly limited, but it is preferable that the integrated amount of light, which is a product of irradiation intensity and irradiation time, is set to 10 mJ / cm ² to 10,000 mJ / cm ² . If the accumulated light quantity is 10 mJ / cm ² or more, the curing reaction can be more surely proceeded by keeping the amount of the active species derived from the initiator sufficiently, and if it is 10,000 mJ / cm ² or less, the irradiation time is not excessively long , Good productivity can be maintained

Exemplary attachment type optical elements of the present invention may also have a layer formed on one side or both sides thereof and including a cured product of the composition or the composition, for example, the above-mentioned point adhesive layer. Examples of the optical element include a polarizing plate, a retardation plate, a reflective layer, a transflective reflective layer, an antireflection layer, a light diffusion layer, a light collecting plate or a brightness enhancement film, or a laminate in which two or more elements are stacked.

In one example, when the optical element is a polarizing plate, the polarizing plate may include, for example, a polarizer; And a layer formed on one side or both sides of the polarizer and including the composition or a cured product of the composition.

The type of the polarizer included in the polarizing plate is not particularly limited, and for example, a conventional type such as a polyvinyl alcohol polarizer which is uniaxially stretched and in which iodine or a dichroic dye is adsorbed and aligned can be used.

As the polyvinyl alcohol resin of the polarizer, for example, a gelated polyvinyl acetate resin can be exemplified. As the polyvinyl acetate resin, a homopolymer of vinyl acetate or a copolymer of vinyl acetate and another comonomer may be used. Examples of other comonomers include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The degree of gelation of the polyvinyl alcohol resin is usually 85 mol% to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used.

As the polarizer protective film that can be attached to one surface or both surfaces of the polarizer, a polarizer protective film such as a cellulose resin film such as TAC (triacetyl cellulose) or DAC (diacetyl cellulose) is used as a polarizer protective film as well as an amorphous polyolefin (Such as a film, a polyester resin film, an acrylic resin film, a polycarbonate resin film, a polysulfone resin film, an alicyclic polyimide resin film or a cyclic olefin (COP) May also be used.

The method of forming the point adhesive layer on the optical element is not particularly limited. For example, the composition or the coating solution containing the composition may be applied by a coating method using a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, a bar coater, or the like, followed by drying or, if necessary, A method of forming a layer can be used.

An exemplary display device of the present invention may be, for example, an LCD, and the LCD may include the optical element or the polarizing plate described above. When the LCD includes a polarizing plate, the LCD includes a liquid crystal panel; And the polarizer attached to one or both surfaces of the liquid crystal panel.

Examples of the liquid crystal panel include a variety of passive matrix methods including TN (Twisted Neumatic) type, STN (Super Twisted Neumatic) type, F (ferroelectric) type and PD (polymer dispersed LCD) type; Various active matrix systems including two-terminal and three-terminal; An IPS mode panel and a VA mode panel may be exemplified.

Exemplary compositions of the present invention are used in the attachment of optical elements and are applied in the form of a tackifier in use and can be cured to produce higher bond strength. The composition can be cured to exhibit a high modulus of elasticity and a peeling force at the same time, and thus it is possible to provide an optical element excellent in durability and dimensional stability even when it is left under severe conditions. In addition, the composition does not require an additional aging process after curing in the curing process, is suppressed from aging, and is optically transparent.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited by the following examples.

The physical properties of the present examples and comparative examples were evaluated in the following manner.

1. Evaluation of weight average molecular weight and molecular weight distribution

The weight average molecular weight and the molecular weight distribution of the pressure-sensitive adhesive resin are measured using the GPC method under the following conditions, and the calibration curve is prepared using the standard polystyrene (manufactured by Agilent system).

<Conditions for measuring weight average molecular weight>

Meter: Agilent GPC (Agilent 1200 series, USA)

Column: Two PL Mixed B connections

Column temperature: 40 ° C

Eluent: tetrahydrofuran

Flow rate: 1.0 mL / min

Concentration: ~ 2 mg / mL (100 μL injection)

2. Evaluation of tensile modulus

In the present specification, the tensile elastic modulus of the pressure-sensitive adhesive layer is measured by a tensile stress-strain test method according to a standard standard test method prescribed by KS M 3006, ASTM D638, ASTM D882, ISO 572 or BS2782. Specifically, the point-adhesive layer prepared in Example or Comparative Example was interposed between two PET release films (thickness: 38 mu m, MRF-38) and cured by irradiating ultraviolet rays (ultraviolet irradiation condition: irradiation intensity : About 250 mW / cm ² , cumulative light amount: about 200 mJ / cm ² ) (thickness of the cured pressure-sensitive adhesive layer: 25 μm). A PET release film, a cured pressure-sensitive adhesive layer and a PET release film were cut to prepare a specimen, and the both ends of the specimen were fixed with a tensile test jig, and then the tensile elastic modulus was measured under the following conditions.

&Lt; Measurement conditions of tensile elastic modulus &

Specimen type: dog bone type (length × width = 7cm × 1cm)

Measuring instruments: Universal Testing Machine (UTM)

Equipment Model: Zwick Roell Z010, Instron Corporation

Measuring conditions:

Load cell: 500 N, tensile speed: 3 mm / sec

2. Evaluation of peel strength and long-term peel strength

A polarizing plate having one side of the pressure-sensitive adhesive layer prepared in the example or the comparative example is cut to a size of 1 inch x 1 inch (width x length) to prepare a specimen. The releasing film was peeled off, and the specimen was adhered to a non-alkali glass through a laminator with a laminating adhesive, followed by irradiation with ultraviolet light to cure the laminating adhesive layer (ultraviolet irradiation condition: irradiation intensity: about 250 mW / cm ² , : About 200 mJ / cm ² ). Peel strength is measured at a peeling angle of 180 degrees and a peeling speed of 300 mm / min using a UTM (UNIVERSAL TESTING MACHINE) at a point of time 30 minutes after it is attached to the glass. Further, the same polarizing plate is allowed to stand for 30 days, then attached to the alkali-free glass in the same manner as described above, and the long-term peeling force is measured in the same manner.

<Peel strength evaluation standard>

?: Peel force of 2,000 gf / 25 mm or more

B: Peel strength is 1,000 gf / 25 mm or more, less than 2,000 gf / 25 mm

X: Peel force less than 1,000 gf / 25 mm

3. Endurance reliability evaluation

A polarizing plate having a surface adhesive formed on one surface thereof was cut into a size of 34 cm x 27 cm (width x length) to prepare a test piece. The specimen is attached to a liquid crystal cell and irradiated with ultraviolet rays to cure the point-adhesive layer (ultraviolet irradiation condition: irradiation intensity: about 250 mW / cm ² , cumulative light amount: about 200 mJ / cm ² ). After curing, it was stored in an autoclave at 40 DEG C and 0.5 MPa for 30 minutes, and again left in an atmosphere at a temperature of 60 DEG C and an atmosphere of relative humidity of 90% for 150 hours, and then visually observed to evaluate durability .

<Evaluation Criteria for Durability>

○: No bubbles and peeling occurred

B: Bubbles and / or slight peeling occurred

X: large amount of bubbles and / or peeling occurred

4. Evaluation of deformability of protective film

A polarizing plate formed on one surface of a polarizer protective film (TAC) prepared in Examples or Comparative Examples was cut into a size of 34 cm x 27 cm (width x length) to prepare a test piece. Subsequently, the specimen was attached to the glass substrate via a point adhesive layer, and the point adhesive layer was cured by irradiating ultraviolet rays (ultraviolet irradiation condition: irradiation intensity: about 250 mW / cm ² , total light amount: about 200 mJ / cm ² ) . Thereafter, the specimen attached to the glass substrate was left at a temperature of 80 DEG C for 72 hours, and then the degree of deformation of the protective film (TAC) of the polarizing plate was measured using STM6-LM manufactured by OLYMPUS. The degree of the deformation was measured in both the transverse direction and the longitudinal direction of the protective film, and the average value thereof was determined to be numerically expressed in Table 1 below.

5. Measurement of Haze

The point adhesive prepared in Examples or Comparative Examples was cut into a size of 5 cm x 5 cm (width x length), and the cut point adhesive thus cut was attached to the glass substrate. After that, the point adhesive is irradiated with ultraviolet rays to cure (ultraviolet irradiation condition: irradiation intensity: about 250 mW / cm ² , cumulative light amount: about 200 mJ / cm ² ). Then, the haze of the adhesive layer was measured using a hazemeter (HM-150, Murakami Color Research Laboratory) and evaluated according to the following criteria.

Production Example 1. Preparation of adhesive resin (A)

60 parts by weight of n-butyl acrylate (n-BA) and 40 parts by weight of methoxyethyl acrylate (MEA) were added to a 1 L reactor equipped with a cooling device so that nitrogen gas was refluxed and temperature was easily controlled. The reactor was charged with 149.1 parts by weight of ethyl acetate (EAc), and the nitrogen gas was purged for about 1 hour. The reactor temperature was adjusted to 62 ° C, 400 ppm of AIBN (azobisisobutyronitrile) and 400 ppm of n-dodecyl mercaptan (n-DDM) were added and reacted. After the reaction, the pressure-sensitive adhesive resin (A) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive resin (A) having a viscosity of about 2,400 cps at room temperature, a solid concentration of 27% by weight, a molecular weight of 600,000 and a molecular weight distribution of 2.4.

Production Example 2. Preparation of adhesive resin (B)

except that 70 parts by weight of n-BA and 30 parts by weight of MEA were added to the reactor, polymerization was carried out in the same manner as in Preparation Example 1, and the viscosity at room temperature was about 850 cps, the solid concentration was 29 wt% A pressure-sensitive adhesive resin (B) having a molecular weight of 630,000 and a molecular weight distribution of 2.39 was prepared.

Production Example 3. Preparation of adhesive resin (C)

Polymerization was carried out in the same manner as in Preparation Example 1, except that 99 parts by weight of n-BA and 1 part by weight of hydroxybutyl acrylate (HBA) were added to the reactor, and the viscosity at room temperature was about 5,000 cps. A pressure-sensitive adhesive resin (C) having a concentration of 15.5 wt%, a molecular weight of about 600,000, and a molecular weight distribution of about 2.06 was prepared.

Production Example 4. Preparation of adhesive resin (D)

Polymerization was carried out in the same manner as in Preparation Example 1 except that only n-BA was added to the reactor. The polymerization was carried out at room temperature with a viscosity of about 3,000 cps, a solid concentration of 27% by weight, a molecular weight of 600,000, To obtain a pressure-sensitive adhesive resin (D) having a distribution of 2.53.

Example 1

20 parts by weight of an alicyclic epoxy compound (celloxide C2021P), 10 parts by weight of an aliphatic epoxy compound (trimethylol propane triglycidyl ether), 10 parts by weight of a cationic initiator (IHT-PI 45, 6 parts by weight of 50 wt% mixed triarylsulfonium hexafluorophosphate salt 50 wt% propylene carbonate and 30 parts by weight of cellulose acetate butyrate (CAB) were mixed and homogeneously mixed to prepare an optical element attachment composition. Subsequently, the above composition was coated on a release treated surface of a release-treated PET (poly (ethyleneterephthalate)) film (thickness: 38 μm, MRF-38, manufactured by Mitsubishi) and dried at 120 ° C. for 3 minutes to form a point adhesive layer . Thereafter, the adhesive layer was laminated on one surface of a polarizing plate having a protective film (TAC) on both surfaces of the polyvinyl alcohol polarizer, to produce an adherend type polarizing plate.

Example 2

A polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive resin (B) was used as the pressure-sensitive adhesive resin.

Example 3

A polarizing plate was prepared in the same manner as in Example 1 except that the weight ratio of the alicyclic epoxy compound and the aliphatic epoxy compound was adjusted to 15 parts by weight.

Example 4

A polarizing plate was prepared in the same manner as in Example 2 except that the weight ratio of the alicyclic epoxy compound and the aliphatic epoxy compound was adjusted to 15 parts by weight.

Comparative Example 1

0.5 part by weight of a multifunctional crosslinking agent (TDI isocyanate, Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) relative to 100 parts by weight of the solid content of the resin (C), 0.5 part by weight of a multifunctional acrylate (trifunctional urethane acrylate Except that 15 parts by weight of a photoinitiator (Aronix M-315, manufactured by Dongwoo Chemical) and 6 parts by weight of 2-hydroxy-2-methylphenylpropan-1-one as a photoinitiator were used, A polarizing plate was produced in accordance with Example 1.

Comparative Example 2

A polarizing plate was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive resin (D) prepared in Preparation Example 4 was used as the pressure-sensitive adhesive resin.

Comparative Example 3

A polarizing plate was produced in the same manner as in Example 1, except that no alicyclic epoxy compound, aliphatic epoxy compound, cationic initiator and CAB were added.

Comparative Example 4

A polarizing plate was produced in the same manner as in Example 1, except that the alicyclic epoxy compound and the aliphatic epoxy compound were not added.

Comparative Example 5

A polarizing plate was produced in the same manner as in Example 1, except that no CAB was added during the preparation of the composition for optical element attachment.

Comparative Example 6

A polarizing plate was produced in the same manner as in Example 1 except that the weight ratio of the optical alicyclic epoxy compound was changed to 20 parts by weight and the weight ratio of the aliphatic epoxy compound was changed to 30 parts by weight.

The physical properties measured for Examples and Comparative Examples are summarized in Table 1 below.

Example Comparative Example One 2 3 4 One 2 3 4 5 6 Peel force ○ ○ ○ ○ × ○ × × × × Long-term peel force ○ ○ ○ ○ × ○ × × × × Endurance reliability ○ ○ ○ ○ ○ × × △ × × Tensile modulus 0.42 0.46 0.36 0.38 0.4 0.36 0.02 0.026 0.43 0.48 Transforming protective film 80 90 95 95 200 100 500 540 95 50 Hayes 0.5 0.5 0.5 0.6 0.5 1.2 0.5 0.5 0.5 2.0 Tensile modulus Unit: MPa
Degree of Deformation of Protective Film Unit: ㎛
Haze Units:%

Claims (20)

A pressure-sensitive adhesive resin comprising a monomer of the following formula (1) as a polymerization unit; 1 to 30 parts by weight of an alicyclic epoxy compound based on 100 parts by weight of the pressure-sensitive adhesive resin, 1 to 25 parts by weight of an aliphatic epoxy compound per 100 parts by weight of the pressure-sensitive adhesive resin, and 1 to 60 parts by weight A composition for an optical element comprising a cellulose ester compound in a part:
[Chemical Formula 1]

Wherein R is hydrogen or an alkyl group, A is an alkylene group or an alkylidene group, K is an alkyl group or an aryl group, and n is a number of 1 to 50. The composition for an optical element according to claim 1, wherein the adhesive resin is a non-crosslinkable adhesive resin. The composition for an optical element according to claim 1, wherein the adhesive resin comprises 40 to 90 parts by weight of a (meth) acrylic acid ester monomer and 10 to 70 parts by weight of a monomer of the formula (1) as polymerized units. The method according to claim 1, wherein the alicyclic epoxy compound is an epoxycyclohexylmethyl epoxycyclohexanecarboxylate compound; Epoxycyclohexanecarboxylate compounds of alkanediol; An epoxycyclohexylmethyl ester compound of dicarboxylic acid; Epoxycyclohexyl methyl ether compounds of polyethylene glycol; Epoxycyclohexyl methyl ether compounds of alkanediol; Diepoxy trispyrene compounds; Diepoxy monospiro compounds; Vinylcyclohexene diepoxide compounds; An epoxy cyclopentyl ether compound or a diepoxy tricyclodecane compound. The method according to claim 1, wherein the alicyclic epoxy compound is selected from the group consisting of 7-oxabicyclo [4,1,0] heptane-3-carboxylic acid and (7-oxa-bicyclo [ Esters with methanol; Ester of 4-methyl-7-oxabicyclo [4,1,0] heptane-3-carboxylic acid with (4-methyl-7-oxa-bicyclo [ freight; Esters of 7-oxabicyclo [4,1,0] heptane-3-carboxylic acid with 1,2-ethanediol; (7-oxabicyclo [4,1,0] hept-3-yl) methanol and adipic acid; (4-methyl-7-oxabicyclo [4,1,0] hept-3-yl) methanol and adipic acid; And (7-oxabicyclo [4,1,0] hepto-3-yl) methanol and an etherified product of 1,2-ethanediol. The method of claim 1, wherein the aliphatic epoxy compound is selected from the group consisting of polyglycidyl ether of an aliphatic polyhydric alcohol; Polyglycidyl ethers of alkylene oxide adducts of aliphatic polyhydric alcohols; Polyglycidyl ethers of polyester polyols of aliphatic polyhydric alcohols and aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of polyester polycarboxylic acids of aliphatic polyhydric alcohols and aliphatic polyvalent carboxylic acids; Dimers, oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate; Or an oligomer or polymer obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate and other vinyl monomers. The composition for an optical element according to claim 1, wherein the aliphatic epoxy compound comprises an aliphatic epoxy group which is not an alicyclic epoxy group and contains at least three epoxy groups. The composition for an optical element according to claim 1, wherein the cellulose ester compound is a cellulose acetate alkylate. The composition for an optical element according to claim 8, wherein the alkylate comprises from 1 to 20 carbon atoms. The composition for an optical element according to claim 1, wherein the cellulose ester compound is cellulose acetate butyrate or cellulose acetate propionate. The composition for an optical element according to claim 1, further comprising a cationic initiator. 12. The composition for an optical element according to claim 11, wherein the cationic initiator is an ionic cationic photoinitiator based on an onium salt. The composition for an optical element according to claim 11, wherein the cationic initiator is contained in an amount of 1 part by weight to 60 parts by weight based on 100 parts by weight of the epoxy compound. The composition for an optical element according to claim 1, further comprising an oxetane compound, a photosensitizer or a polyol compound. The composition for an optical element according to claim 1, having a modulus of elasticity of 0.3 MPa or more after being cured. The composition for an optical element according to claim 1, wherein the peel strength after curing is 1,500 gf / 25 mm or more. An adhesive resin comprising a monomer represented by the following formula (1); 1 to 30 parts by weight of an alicyclic epoxy compound based on 100 parts by weight of the pressure-sensitive adhesive resin, 1 to 25 parts by weight of an aliphatic epoxy compound per 100 parts by weight of the pressure-sensitive adhesive resin, and 1 to 60 parts by weight Or a layer containing the above-mentioned composition in a cured state.
[Chemical Formula 1]

Wherein R is hydrogen or an alkyl group, A is an alkylene group or an alkylidene group, K is an alkyl group or an aryl group, and n is a number of 1 to 50. An attachment type optical element having the composition according to claim 1 or a layer containing the composition in a cured state on one surface or both surfaces. An attachment type polarizing plate having the composition according to claim 1 or a layer containing the composition in a cured state on one surface or both surfaces. A liquid crystal display comprising the optical element according to claim 18 or the polarizing plate according to claim 19.