TWI570204B - Adhesive layer and adhesive film - Google Patents

Description

Adhesive layer and adhesive film

The present invention relates to an adhesive layer and an adhesive film for interlayer bonding or the like of an optical member. More specifically, the present invention provides an adhesive layer which has a high adhesion and high adhesion property as a film having a thickness of only 1 μm to 20 μm, and an adhesive film using the adhesive layer.

In order to bond an optical member such as a polarizing plate or a retardation film to an adherend such as a liquid crystal cell through an adhesive layer, various adhesive films have been proposed (for example, refer to Patent Documents 1 and 2).

Patent Document 1 describes an optical adhesive composition containing a butyl acrylate or the like as a main component and containing an acrylamide compound or the like.

Patent Document 2 describes a monomer having a (meth) acrylate having an alkyl group having 4 to 8 carbon atoms as a main component, and having a carboxyl group-containing monomer and a nitrogen atom-containing vinyl monomer. Optical adhesive composition.

Further, various adhesive films which have been repeatedly studied in order to increase the refractive index of the adhesive layer have been proposed (for example, refer to Patent Documents 3 to 8).

Patent Document 3 describes an optical adhesive composition having an aromatic ring and containing a tackifier having a refractive index of 1.51 to 1.75.

Patent Document 4 describes an adhesive sheet comprising an adhesive composition containing a copolymerizable polymer which is a copolymerizable polymer of an aromatic ring-containing acrylic modified monomer.

Patent Document 5 describes an optical adhesive composition comprising an aromatic ring-containing tackifying resin and an aromatic phosphate plasticizer.

Patent Document 6 describes an adhesive formed by curing an adhesive composition comprising: an acrylic resin; and an aromatic compound containing one ethylenically unsaturated group.

Patent Document 7 describes an optical member in which a retardation film and a birefringent plate are fixed to each other by an acrylic adhesive containing an aromatic monomer.

Patent Document 8 describes an adhesive composition containing a polyurethane resin obtained by reacting an aromatic diisocyanate with an aromatic polyester diol.

In recent years, in order to achieve thinning of an optical member, an adhesive film for bonding an interlayer of an optical member is required to be an adhesive film having a thickness of the adhesive layer as thin as 20 μm or less.

Generally, the adhesive force of the adhesive layer is approximately proportional to the thickness of the adhesive layer. Therefore, if the thickness of the adhesive layer is made thinner, the adhesive force is lowered.

However, in recent years, it is required that the adhesive film has the same performance as that of the conventional adhesive film (the adhesive layer is a thick layer having a thickness of about 30 μm) even when the thickness of the adhesive layer is reduced, and for high temperature, In the high-humidity environment, the durability after standing for a long period of time also has the same performance as that of the conventional adhesive film.

In addition, from the viewpoint of being able to reduce the thickness of the adhesive layer and forming an adhesive layer which does not require aging treatment (curing at a constant temperature), it is required to form NCF (Non). The form of the carrier film (non-supporting film) is composed of only a member having an adhesive layer obtained by removing the adhesive film substrate and having a "release film/adhesive layer/release film".

Further, in the conventional adhesive film, since the adhesive film is bonded to the adherend and then subjected to aging treatment, the adhesion between the adherend and the adhesive layer can be improved.

However, in the case of the adhesive film using the NCF form, since the aging treatment of the adhesive layer has been completed, the adhesion between the adherend and the adhesive layer is insufficient. Based on this, there is a problem that it is necessary to perform surface treatment such as corona treatment on the surface of the adherend.

There is therefore a need for an adhesive film that meets these requirements and overcomes these problems.

Prior art literature

Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-177022

Patent Document 2: JP-A-2012-201734

Patent Document 3: Japanese Laid-Open Patent Publication No. 2007-084762

Patent Document 4: Japanese Laid-Open Patent Publication No. 2011-153169

Patent Document 5: Japanese Laid-Open Patent Publication No. 2012-167188

Patent Document 6: Japanese Laid-Open Patent Publication No. 2012-021148

Patent Document 7: Japanese Laid-Open Patent Publication No. 2006-293281

Patent Document 8: JP-A-2009-091522

The present invention has been made in view of the above circumstances, and an object of the invention is to provide an adhesive layer having a high adhesion and high adhesion property even though a film having a thickness of 1 μm to 20 μm, and the use of the adhesive. Adhesive film of the agent layer.

In order to solve the above problems, the technical idea of the present invention is to form a methyl group having an alkyl group having a carbon number of C1 to C14 in an adhesive layer obtained by crosslinking an adhesive composition comprising an acrylic polymer. a monomer having at least one of an alkyl acrylate monomer as a main component, and at least one or more of vinyl monomers having a copolymerizable nitrogen atom as another copolymerizable monomer, and copolymerizing them And cross-linking, thereby forming an adhesive layer having both tough adhesion and high adhesion properties.

Further, in order to solve the above problems, the present invention provides an adhesive layer in which an acrylic polymer is contained as a main component in an adhesive layer obtained by crosslinking an adhesive composition containing an acrylic polymer. a copolymer of an acrylate monomer and another copolymerizable monomer, wherein the (meth) acrylate monomer as a main component includes an alkyl (meth) acrylate having an alkyl group having a C1 to C14 carbon number. At least one or more of the monomers and at least one of the aryl group-containing (meth) acrylate monomers. The other copolymerizable monomer includes at least one of at least one of a nitrogen atom-containing vinyl monomer and a hydroxyl group-containing copolymerizable vinyl monomer. Further, the crosslinking agent which crosslinks the pressure-sensitive adhesive composition is a trifunctional isocyanate compound, the thickness of the pressure-sensitive adhesive layer is from 1 μm to 20 μm, and when the thickness is 20 μm, the initial adhesion of the bonding is 3.0 (N/25 mm). Above, the refractive index is 1.47 to 1.50.

Further, it is preferred to include in the aforementioned adhesive composition: a copolymer having a weight average molecular weight of 200,000 to 2,000,000, wherein the copolymer is a (meth)acrylic acid alkyl ester having a C1 to C14 carbon number of 70 to 95 parts by weight of the (A) alkyl group. 100 parts by weight of at least one or more of the body and at least one of 5 to 30 parts by weight of the (B) aryl group-containing (meth) acrylate monomer, having 2 to 50 parts by weight ( And C) at least one of a nitrogen atom-containing vinyl monomer and 0.1 to 10 parts by weight of (D) a hydroxyl group-containing copolymerizable vinyl monomer; and, 0.001 to 1 part by weight (E) a trifunctional isocyanate compound.

Further, it is preferable that the acrylic polymer does not contain a copolymerizable vinyl monomer having a carboxyl group as a monomer.

Further, the gel fraction of the adhesive layer is preferably from 50% to 70%.

Further, it is preferable that the pressure-sensitive adhesive composition contains 0.1 to 5.0 parts by weight of an ionic compound having a melting point of 25 to 50 ° C, and the surface resistivity of the pressure-sensitive adhesive layer is 5.0 × 10 ^{+ 10} Ω / □ or less.

Further, the present invention provides an adhesive film comprising the above-described adhesive layer formed on one surface of a release film and having a release film/adhesive layer/release film.

Further, the present invention provides an adhesive film obtained by laminating the above-mentioned adhesive layer on one surface of a substrate.

Further, the present invention provides an adhesive film for bonding a polarizing plate and a display panel, which uses the above-mentioned adhesive film.

Further, the present invention provides a film for a touch panel using an adhesive film.

Further, the present invention provides a film for an electronic paper using the above adhesive film.

Further, the present invention provides an optical film with an adhesive layer in which the aforementioned adhesive layer is laminated on at least one surface of the optical film.

According to the present invention, it is possible to satisfy the requirements of the prior art and overcome the problems in the prior art, and it is possible to provide an adhesive layer having high adhesion and high adhesion properties even in a film having a thickness of 1 μm to 20 μm. An adhesive film using the adhesive layer can also be provided.

Hereinafter, the present invention will be described based on preferred embodiments.

The adhesive layer of the present invention is characterized in that the acrylic polymer contains (meth) acrylate as a main component in an adhesive layer obtained by crosslinking an adhesive composition containing an acrylic polymer. a copolymer of a monomer and another copolymerizable monomer, wherein the (meth) acrylate monomer as a main component includes an alkyl (meth) acrylate monomer having an alkyl group having a C1 to C14 carbon number; At least one or more of at least one or more aryl group-containing (meth) acrylate monomers, and at least one or more of the other copolymerizable monomers including a nitrogen atom-containing vinyl monomer and a hydroxyl group-containing copolymerization property At least one or more of the vinyl monomers, and the crosslinking agent for crosslinking the above-mentioned adhesive composition is a trifunctional isocyanate compound, the thickness of the adhesive layer is 1 μm to 20 μm, and when the thickness is 20 μm, the bonding is performed. The initial adhesion is 3.0 (N/25 mm) or more, and the refractive index is 1.47 to 1.50.

In the present specification, the description of the content of the (including) monomer in the acrylic polymer (copolymer) mainly means that the monomer is copolymerized in the acrylic polymer (copolymer), but the raw material list is not excluded. A part of the body remains in the acrylic polymer (copolymer) in an unreacted state.

The (meth)acrylic acid alkyl ester monomer having an alkyl group having C1 to C14 carbon atoms may, for example, be methyl (meth)acrylate, ethyl (meth)acrylate or propyl (meth)acrylate. , isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate , octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, (methyl ) decyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, ( At least one of cyclopentyl methyl methacrylate and cyclohexyl (meth) acrylate. The alkyl group in the alkyl (meth) acrylate monomer may be any of a linear chain, a branched chain, and a cyclic group. It is preferably 100 parts by weight based on 100 parts by weight of the (meth)acrylic acid ester monomer having (C) alkyl group having C1 to C14 and (B) aryl group-containing (meth)acrylic acid ester monomer. The content of the alkyl (meth) acrylate monomer having an alkyl group having from C1 to C14 is from 70 to 95 parts by weight.

Examples of the aryl group-containing (meth) acrylate monomer include benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, and phenoxy (meth) acrylate. Butyl ester, 2-(1-naphthalenyloxy)ethyl (meth)acrylate, 2-(2-naphthalenyloxy)ethyl (meth)acrylate, 6-(1-naphthyloxy)(meth)acrylate Hexyl ester, 6-(2-naphthyloxy)hexyl (meth)acrylate, 8-(1-naphthalenyloxy)octyl (meth)acrylate, 8-(2-naphthyloxy)(meth)acrylate Ethyl octyl ester, ethylene glycol o-phenyl phenyl ether (meth) acrylate, polyethylene glycol o-phenyl phenyl ether (meth) acrylate, and the like. In order to obtain an adhesive layer having a high refractive index, it is preferred to mix at least one or more aryl group-containing (meth) acrylate monomers.

By mixing these aryl group-containing (meth) acrylate monomers with a monomer as a main component, that is, an alkyl (meth) acrylate monomer having an alkyl group having a C1 to C14 carbon number The refractive index of the obtained adhesive layer can be adjusted to be adjusted, the refractive index difference between the optical members can be reduced, and total reflection can be reduced, whereby the total light transmittance can be improved.

Further, in the adhesive layer of the present invention, (B) an aryl group is preferred, based on 100 parts by weight of the (meth) acrylate monomer as a main component which adds the above (A) and the above (B). The content of the (meth) acrylate monomer is 5 to 30 parts by weight.

Examples of the vinyl monomer containing a nitrogen atom include a cyclic nitrogen-vinyl compound such as N-vinylpyrrolidone, N-vinylcaprolactam, or (meth)acryl hydrazine morpholine; N-ethyl- N-methyl (meth) acrylamide, N-methyl-N-propyl (meth) acrylamide, N-methyl-N-isopropyl (meth) acrylamide, N, N - dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl Dialkyl substituted (meth) acrylamide such as (meth) acrylamide or N,N-dibutyl(meth) acrylamide; N-ethyl-N-methyl (meth) acrylate Amine ethyl ester, N-methyl-N-propylamine ethyl (meth)acrylate, N-methyl-N-isopropylamine ethyl (meth)acrylate, N,N-(meth)acrylate Dimethylamine methyl ester, N,N-dimethylamine ethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-dimethyl (meth)acrylate a dialkylamine (meth)acrylate such as ketamine, N,N-dipropylamine ethyl (meth)acrylate or N,N-dibutylamine ethyl (meth)acrylate; -ethyl-N-methylaminopropyl (meth) acrylamide, N-methyl -N-propylaminopropyl (meth) acrylamide, N-methyl-N-isopropylamine propyl (meth) acrylamide, N,N-dimethylaminopropyl (methyl Acrylamide, N,N-diethylaminopropyl (meth) acrylamide, N,N-dipropylaminopropyl (meth) acrylamide, N, N - Dialkyl substituted aminoalkyl (meth) acrylamide such as dimethylamine ethyl (meth) acrylamide or N, N-diethylamine ethyl (meth) acrylamide At least one of the above.

In order to distinguish it from the compound (D) described later, the nitrogen atom-containing vinyl monomer preferably does not contain a hydroxyl group, and more preferably does not contain a hydroxyl group or a carboxyl group. As such a monomer, preferred are the above-exemplified monomers, for example, an acrylic monomer having an N,N-dialkyl substituted amine group or an N,N-dialkyl substituted guanamine group; N-vinylpyrrolidone, An N-vinyl substituted indoleamine such as N-vinyl caprolactam or an N-(meth)acrylinyl substituted cyclic amine such as N-(meth)acryloquinone.

Further, in the adhesive layer of the present invention, the nitrogen atom-containing vinyl monomer contained in the acrylic polymer of the adhesive composition can impart the necessary adhesive force and durability to the adhesive layer. In the adhesive layer of the present invention, the aforementioned acrylic acid of the adhesive composition is preferably used in an amount of 100 parts by weight based on 100 parts by weight of the (meth) acrylate monomer as a main component to which the above (A) and the above (B) are added together. The content of the nitrogen atom-containing vinyl monomer contained in the polymer is 2 to 50 parts by weight.

Further, in the adhesive layer of the present invention, it is particularly preferable to use N-vinylpyrrolidone or N,N-dimethyl group as the nitrogen atom-containing vinyl monomer contained in the acrylic polymer as the adhesive composition. (Meth) acrylamide, N,N-diethyl(meth) acrylamide, N,N-dipropyl(meth) acrylamide, N,N-diisopropyl (methyl) Acrylamide, N,N-dibutyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N,N-diethylaminopropyl (methyl) And acrylamide, N,N-dimethylamine ethyl (meth) acrylamide, N-vinyl caprolactam, and the like.

Examples of the hydroxyl group-containing copolymerizable vinyl monomer (hydroxyl group-containing monomer) include 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and (methyl). a hydroxyalkyl (meth) acrylate such as 4-hydroxybutyl acrylate or hydroxyethyl (meth) acrylate; N-hydroxy(meth) acrylamide, N-methylol (meth) propylene oxime At least one of a hydroxyl group-containing (meth) acrylamide such as an amine or N-hydroxyethyl (meth) acrylamide.

Further, in the adhesive layer of the present invention, the hydroxyl group-containing monomer which is contained in the acrylic polymer of the adhesive composition can be used as a copolymerizable monomer for reducing the content of a carboxyl group-containing monomer. The carboxyl group-containing monomer causes the obtained adhesive layer to have a corrosive effect on the easily corroded adherend such as the surface of the ITO (indium tin oxide) of the transparent conductive film. Therefore, the hydroxyl group-containing monomer can contribute to the adhesion of the adhesive layer and reduce corrosion. In the adhesive layer of the present invention, the aforementioned acrylic acid of the adhesive composition is preferably used in an amount of 100 parts by weight based on 100 parts by weight of the (meth) acrylate monomer as a main component to which the above (A) and the above (B) are added together. The content of the hydroxyl group-containing monomer in the polymer is from 0.1 to 10 parts by weight.

The copolymer of the adhesive composition for the adhesive layer of the present invention is preferably blended in an amount of 2 to 50 parts by weight based on 100 parts by weight of the (meth) acrylate monomer as a main component (C). One or more of a nitrogen atom-containing vinyl monomer, and 0.1 to 10 parts by weight of at least one of (D) a hydroxyl group-containing copolymerizable vinyl monomer, wherein the main component (A) The acrylate monomer comprises 70 to 95 parts by weight of at least one or more of (A) alkyl groups having a C1 to C14 alkyl (meth) acrylate monomer, and 5 to 30 parts by weight. (B) at least one or more of aryl group-containing (meth) acrylate monomers.

Further, it is preferable that the acrylic polymer does not include a carboxyl group-containing copolymerizable vinyl monomer as its monomer. When the polymer contains a carboxyl group, there is a possibility that the acid corrodes an adherend such as ITO.

The polymerization method of the copolymer is not particularly limited, and a suitable known polymerization method such as a solution polymerization method or an emulsion polymerization method can be used. The weight average molecular weight of the copolymer is preferably from 200,000 to 2,000,000.

The copolymer is preferably an acrylic polymer, and preferably contains 50 to 100% by weight of an acrylic monomer such as a (meth) acrylate monomer or a (meth) acrylamide.

Preferably, the adhesive layer has a gel fraction of 50% to 70%.

In the above adhesive composition, characteristics such as desired physical properties can be adjusted by blending the above-mentioned copolymer with a crosslinking agent and a suitable optional additive.

As the crosslinking agent, for example, a biuret modification of diisocyanate such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate or benzodimethyl diisocyanate is preferable. (E) a trifunctional isocyanate compound, such as an adduct of an isocyanurate modified product or an adduct of a trivalent or higher polyhydric alcohol such as trimethylolpropane or glycerol.

The trifunctional isocyanate compound is preferably an isocyanurate of a hexamethylene diisocyanate compound, an isocyanurate of an isophorone diisocyanate compound, or an adduct of a hexamethylene diisocyanate compound. An adduct of a phorone diisocyanate compound, a biuret of a hexamethylene diisocyanate compound, a biuret of an isophorone diisocyanate compound, an isocyanurate of a toluene diisocyanate compound, a benzene dimethyl group An isocyanurate of a diisocyanate compound, an isocyanurate of a hydrogenated dimethylated diisocyanate compound, an adduct of a toluene diisocyanate compound, an adduct of a benzene dimethylene diisocyanate compound, and a hydrogenated phthalic acid At least one or more of the compound groups composed of the adduct of the bis-isocyanate compound.

In the case where a trifunctional isocyanate compound is used to crosslink the copolymer, it is preferred that the copolymer has a functional group (particularly a hydroxyl group) capable of crosslinking reaction with a crosslinking agent, and is excellent. A monomer having these functional groups in a side chain is selected. Further, the adhesive composition preferably contains 0.001 to 1 part by weight of the (E) trifunctional isocyanate compound as a crosslinking agent. Further, the basis of the parts by weight is the same as (A) to (D) in the above copolymer.

In order to impart antistatic properties, the adhesive composition of the present invention may contain an antistatic agent. The antistatic agent is preferably a solid at normal temperature (for example, 25 ° C). More specifically, the antistatic agent is an ionic compound having a melting point of 25 to 50 °C. The antistatic agent may be a quaternary ammonium salt type ionic compound containing an acrylonitrile group.

Since these antistatic agents have a low melting point and a long-chain alkyl group, they are presumed to have high affinity with an acrylic polymer.

When the antistatic property is imparted, the surface resistivity of the adhesive layer obtained by crosslinking the above-mentioned adhesive composition is preferably 5.0 × 10 ^{+ 10} Ω / □ or less.

The antistatic agent having an ionic compound having a melting point of 25 to 50 ° C is an ionic compound having a cation and an anion, and examples of the cation include a pyridinium cation, an imidazolium cation, a pyrimidine cation, a pyrazolium cation, and a pyrrole. a nitrogen-containing phosphonium cation such as a phosphonium cation or an ammonium cation, or a phosphonium cation or a phosphonium cation, and the anion is hexafluorophosphate (PF ₆ ^- ), thiocyanate (SCN ^- ), alkylbenzenesulfonate (RC ₆ H _{4 )} A compound of an inorganic or organic anion such as SO ₃ ^- ), perchlorate (ClO ₄ ^- ) or tetrafluoroborate (BF ₄ ^- ). A compound having a melting point of 25 to 50 ° C can be obtained by selecting the chain length of the alkyl group or the position and number of the substituent. Preferably, the cation is a quaternary nitrogen sulfonium cation, and a quaternary pyridinium cation or a 1,3-dioxane such as 1-alkylpyridinium (the carbon atom at the 2nd to 6th position may or may not have a substituent) may be mentioned. A quaternary imide cation such as a quaternary imidazolium cation or a tetraalkylammonium such as a cyazolidinium (the carbon atom at the 2, 4, and 5 positions may have a substituent or may have no substituent).

The quaternary ammonium salt-containing ionic compound containing an acrylonitrile group is an ionic compound having a cation and an anion, and examples thereof include a (meth)acryloxyalkylalkyltrialkylammonium (R ₃ N ^{+ )} -C _n H _2n -OCOCQ=CH ₂ , wherein Q=H or CH ₃ , R=alkyl), etc. (meth)acryloyl group-containing quaternary ammonium; anion is hexafluorophosphate (PF ₆ ^- ) , thiocyanate (SCN ^- ), organic sulfonate (RSO ₃ ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ), fluorinated atom ruthenium (R ^F ₂ N ^- ) A compound of an inorganic or organic anion. (PEI) as the root (R ^F ₂ N ^-) fluorine atoms, R ^F, include trifluoromethanesulfonic acyl, sulfo pentafluoroethyl acyl group such as a perfluoroalkyl sulfonic acyl, acyl-fluoro-sulfo . Examples of the fluorinated atom-containing quinary imine group include bis(fluorosulfonyl) ruthenium root [(FSO ₂ ) ₂ N ^- ], bis(trifluoromethanesulfonyl) fluorenylene root [(CF). ₃ SO ₂ ) ₂ N ^- ], bis(sulfonylsulfonyl) quinone imine [(C ₂ F ₅ SO ₂ ) ₂ N ^- ), etc.

The antistatic agent which is an ionic compound having a melting point of 25 to 50 ° C is not particularly limited. Specific examples of the ionic compound having a pyridinium cation having a melting point of 25 to 50 ° C include 1-octylpyridinium dodecylbenzenesulfonate and 1-dodecylpyridinium thiocyanate. , 3-methyl-1-dodecylpyridinium hexafluorophosphate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl-1-octylpyridinium hexafluorophosphate Salt and so on.

Further, specific examples of the acryl-based quaternary ammonium salt-containing ionic compound include dimethylaminomethyl (meth) acrylate hexafluorophosphate methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ=CH ₂ ‧PF ₆ ^- , wherein Q=H or CH ₃ ], dimethylaminoethyl (meth) acrylate bis(trifluoromethanesulfonyl) fluorene imine methyl salt [(CH) ₃ ) ₃ N ⁺ (CH ₂ ) ₂ OCOCQ=CH ₂ ‧(CF ₃ SO ₂ ) ₂ N ^- , wherein Q=H or CH ₃ ], dimethylaminomethyl (meth)acrylate bis (fluorine Sulfhydryl) quinone imine methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ=CH ₂ ‧ (FSO ₂ ) ₂ N ^- , wherein Q = H or CH ₃ ] and the like.

Further, the content of the ionic compound having a melting point of 25 to 50 ° C is preferably 0.1 to 100 parts by weight of the (meth) acrylate monomer as a main component to which the above (A) and the above (B) are added together. 5.0 parts by weight.

When used for the purpose of bonding an optical member to a display panel or the like, the adhesive composition of the present invention is preferably added with a decane coupling agent. Examples of the decane coupling agent to be added include vinyl trimethoxy decane, vinyl triethoxy decane, vinyl tris(2-methoxyethoxy) decane, and 3-methyl propylene oxime. Propyltrimethoxydecane, 3-methylpropenyloxypropyltriethoxydecane, 3-methylpropenyloxypropylmethyldimethoxydecane, 3-methylpropenyloxy Propylmethyldiethoxydecane, vinyltriethoxydecane, 3-propenyloxypropyltrimethoxydecane, 3-propenyloxypropyltriethoxydecane, 3-epoxy Propoxypropyltrimethoxydecane, 3-glycidoxypropyltriethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, 3-epoxypropoxypropane Methyldiethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, vinyltrichlorodecane, 3-mercaptopropyltrimethoxydecane, 3-mercaptopropyltri Ethoxy decane, 3-mercaptopropylmethyldimethoxydecane, 3-mercaptopropylmethyldiethoxydecane, 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxy Decane, N-2-(aminoethyl)-3-aminopropyltrimethyl Silane-yl, 3-isocyanate propyl trimethoxy Silane, 3-isocyanate propyl triethoxy silane-like. These decane coupling agents may be used singly or in combination of two or more kinds, and the amount thereof is usually preferably 0.001 to 5 parts by weight based on 100 parts by weight of the adhesive composition.

As other optional components, known antioxidants, surfactants, curing accelerators, plasticizers, fillers, crosslinking catalysts, crosslinking inhibitors, curing inhibitors, processing aids, anti-aging agents, and the like can be suitably blended. additive. These may be used alone or in combination of two or more.

The pressure-sensitive adhesive layer of the present invention can be obtained by applying the above-mentioned pressure-sensitive adhesive composition to a substrate or a release film, and then crosslinking the pressure-sensitive adhesive composition.

In the case of bonding between layers for an optical member, etc., it is desirable that the adhesive layer is a thin adhesive layer, and it is preferable that the thickness of the adhesive layer is 1 μm to 20 μm. Further, in general, the adhesive force of the adhesive layer is approximately proportional to the thickness of the adhesive layer, but it is preferable that the initial adhesive force to be bonded when the thickness is 20 μm is 3.0 (N/25 mm) or more.

When the pressure-sensitive adhesive layer of the present invention is bonded to, for example, a polarizing plate (polarizing film) as an optical member, the adhesive force of the pressure-sensitive adhesive layer to the polarizing plate is desirably equal to or higher than the above lower limit value. Usually, the polarizing film is mainly composed of a polyvinyl alcohol (PVA) film to which iodine is adsorbed, and a saponified triethylenesulfonyl cellulose (TAC) or polyethylene terephthalate is provided on the surface thereof. Protective layer such as PET). Therefore, the adhesive strength of the adhesive layer of the present invention to the adherend such as saponified triacetyl cellulose (TAC) is desirably equal to or higher than the above lower limit value.

When the adhesive layer of the present invention is used for interlayer bonding or the like of an optical member, in order to reduce light reflection on the interface between the adhesive layer and the optical member, it is desirable that the refractive index difference be as small as possible. Therefore, the refractive index of the above adhesive layer is preferably 1.47 to 1.50.

The adhesive film of the present invention can be produced by forming the adhesive layer of the present invention on one side of a substrate or a release film.

A resin film such as a polyester film or the like can be used as the release film (separator) for forming the base film of the pressure-sensitive adhesive layer or the protective adhesive surface.

The base film can be prevented from permeating the ketone or fluorine release agent, the coating agent, the ceria particles, or the like on the surface of the resin film opposite to the side on which the adhesive layer is formed. The anti-static treatment by coating or mixing of an antistatic agent can be carried out.

The mold release film is subjected to a mold release treatment by a release agent such as an oxime or a fluorine-based release agent on the surface on the side where the adhesive surface of the pressure-sensitive adhesive layer is bonded.

The "release film/adhesive layer/release film" can be formed by laminating the release film on the both surfaces of one adhesive layer. In this case, the release film on both sides is peeled off sequentially or simultaneously to expose the adhesive surface, and can be bonded to an optical member such as an optical film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an anti-glare film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, and a brightness enhancement film.

The adhesive film of the present invention can be used in the bonding of a polarizing plate and a display panel. Examples of the display panel include a liquid crystal display device, an organic EL (Organic Electro-Luminescence), and the like, but are not limited thereto.

In addition, the adhesive film of the present invention can be used for bonding various optical films, various optical films for touch panels, various optical films for electronic paper, various optical films for organic EL, and the like for peripheral members of liquid crystal displays mainly including polarizing plates. in.

Further, an optical film having an adhesive layer may be prepared by laminating the above-mentioned adhesive layer on at least one surface of these optical films. Specifically, "optical film/adhesive layer/optical film", "optical film/adhesive layer/release film", "optical film/adhesive layer", "optical film/adhesive layer/optical film" /Adhesive layer / optical film", "optical film / adhesive layer / optical film / adhesive layer / release film", "release film / adhesive layer / optical film / adhesive layer / release film", etc. Composition.

For example, when the adhesive layer is protected by a release film like the "optical film/adhesive layer/release film", the release film is peeled off to expose an adhesive such as "optical film/adhesive layer". The composition layer is bonded to another optical film, whereby a structure in which an adhesive layer is used for interlayer bonding such as "optical film/adhesive layer/optical film" can be obtained.

Example

Hereinafter, the present invention will be specifically described based on examples.

<Manufacture of Acrylic Copolymer>

[Example 1]

Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, thereby replacing the air in the reaction device with nitrogen. Then, 90 parts by weight of butyl acrylate, 10 parts by weight of benzyl acrylate, 10 parts by weight of N-vinylpyrrolidone, 2.5 parts by weight of 6-hydroxyhexyl acrylate were added to the reaction apparatus, and 60 was added at the same time. Parts by weight of solvent (ethyl acetate). Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise thereto over 2 hours, and the mixture was reacted at 65 ° C for 6 hours to obtain an acrylic acid copolymer of Example 1 having a weight average molecular weight of 500,000. Solution 1. A part of the acrylic copolymer was used as an acid value measurement sample to be described later.

[Examples 2 to 5 and Comparative Examples 1 to 3]

The operation was carried out in the same manner as in the above-described acrylic copolymer solution 1 of Example 1 except that the composition of each monomer was adjusted as described in (A) to (D) of Table 1, and the examples were obtained. 2 to 5 and the acrylic copolymer solutions of Comparative Examples 1 to 3. Here, although the measurement results are not particularly shown, the copolymers contained in the acrylic copolymer solutions of Examples 2 to 5 and Comparative Examples 1 to 3 have a weight average molecular weight of 200,000 to 2,000,000.

<Manufacture of Adhesive Composition, Adhesive Layer and Adhesive Film>

[Example 1]

In the acrylic copolymer solution 1 of Example 1 produced as described above, 0.5 parts by weight of isocyanurate of a hexamethylene diisocyanate compound (trade name Coronate HX ( HX)) was stirred and mixed, and the adhesive composition of Example 1 was obtained. The adhesive composition is applied onto a release film composed of a polyethylene terephthalate (PET) film coated with an fluorenone resin, and then dried at a temperature of 90 ° C to remove the solvent, and then, The film was aged for 7 days in an environment of 23 ° C and 50% RH to obtain an adhesive film of Example 1 having an adhesive layer obtained by crosslinking the adhesive composition on one side of the release film.

[Examples 2 to 5 and Comparative Examples 1 to 3]

Except that the composition of the additive was adjusted as shown in (E) and (F) of Table 1, the operation was carried out in the same manner as in the above-described adhesive film of Example 1, and Examples 2 to 5 and Comparative Examples 1 to 3 were obtained. Adhesive film.

In Table 1, the numerical values in parentheses indicate the values of the parts by weight of the component (C) to the component (F) obtained by setting the total weight of the component (A) and the component (B) to 100 parts by weight. The ratio of addition to the (C) component to the (F) component. Wherein, in Example 3, the total of the components (A) and (B) is 110 parts by weight, and in Example 5, the total of the components (A) and (B) is 90 parts by weight. In Comparative Example 2, the total of the components (A) and (C) was set to 100 parts by weight.

Further, the compound names corresponding to the abbreviations of the respective components used in Table 1 are shown in Table 2. Here, Coronate ( , registered trademark) HX, Coronate HL and Coronate L-45 are trade names of Nippon Polyurethane Industry Co., Ltd., and D-110N is the trade name of Mitsui Chemicals Co., Ltd. HDI refers to hexamethylene diisocyanate, TDI refers to toluene diisocyanate, and XDI refers to benzenedimethyl diisocyanate.

<Test method and evaluation>

The release film (PET film coated with an oxime resin) was peeled off from the adhesive films of Examples 1 to 5 and Comparative Examples 1 to 3 to expose the adhesive layer, and the adhesive layer was transferred to one side of the polarizing plate (film). on.

<Method for measuring adhesion>

The adhesive layer was transferred to one side of a polarizing plate (film) having a thickness of 180 μm to obtain an adhesive film (an optical film with an adhesive layer) as a sample.

The adhesive film was adhered to the non-tin surface of the soda lime glass washed with acetone by a pressure roller, and then subjected to autoclave treatment at 50 ° C, 0.5 MPa × 20 minutes, and then returned to 23 ° C × 50% RH. In the environment, the peeling strength of the adhesive film after one hour passed was measured by a tensile tester according to JIS Z0237, "Adhesive tape and adhesive sheet test method", and peeling was performed at a speed of 300 mm/min in a 180° direction. The strength acts as the adhesion of the adhesive layer of the adhesive film.

<gel fraction>

The quality of the measurement sample after the aging was completed and before the polarizing plate was bonded was accurately measured, and after immersing in toluene for 24 hours, it was filtered through a 200 mesh wire mesh. Then, after drying the filtrate at 100 ° C for 1 hour, the quality of the residue was accurately measured, and the gel fraction of the adhesive layer (adhesive after crosslinking) was calculated according to the following formula.

Gel fraction (%) = insoluble part quality (g) / adhesive quality (g) × 100

<Test method for adhesion>

The adhesive layer of the adhesive film of the sample after the measurement of the adhesive force was visually confirmed, and the adhesiveness was judged in the state which fell off from the polarizing plate (film) of the base material layer.

○: The adhesive layer was not peeled off from the substrate layer at all.

△: A part of the adhesive layer was separated from the substrate layer and peeled off.

X: The adhesive layer was peeled off from the base material layer and adhered to the glass of the adherend.

<Reworkability>

A 10 cm square adhesive film prepared in the same manner as in the measurement of the adhesion force was applied to the non-tin surface of the soda lime glass by the same method to prepare a sample, which was placed at 70 ° C and dried ( After 24 hours in the environment of Dry, it was taken out to room temperature, and the residual glue on the surface of the adherend when the adhesive film was peeled off from the glass plate was visually confirmed.

○... Confirm that there is no residue at all.

△...... Confirm that there is a slight residual glue.

×...... Clearly confirm that there is residual glue.

<Test method for durability>

A 10 cm square adhesive film prepared in the same manner as in the measurement of the adhesion force was applied to the non-tin surface of the soda lime glass in the same manner to prepare a sample, and the sample was placed at 60 ° C × 90%. After 250 hours in the RH environment, the environment was taken out to 23 ° C × 50% RH, and the state of the adhesive film after 1 hour was visually observed to judge the durability.

○: The adhesive film did not cause peeling and foaming at all.

△: Part of the adhesive film was peeled off and foamed.

×: Peeling and foaming occurred in the entire adhesive film.

<Method for Measuring Refractive Index>

The refractive index of the adhesive layer at 23 ° C was measured using an Abbe refractometer (manufacturer: ERMA, model: ER-2S).

<Method for Measuring Surface Resistivity>

After aging, before peeling off the polarizing plate, peeling off the peeling film (PET film coated with fluorenone resin) to expose the adhesive layer, using a resistivity meter (model HirestaUP-HT450 ( UP-HT450), manufactured by Mitsubishi Chemical Analytech Co., Ltd., measured the surface resistivity of the adhesive layer.

The evaluation results are shown in Table 3. Further, the surface resistivity by "mE + n" to represent "m × 10 ^{+ n"} (where, m is an arbitrary real numbers, n-is a positive integer).

In the adhesive films of Examples 1 to 5, the initial adhesion of the adhesive layer having a thickness of 20 μm was 3.0 N/25 mm or more, and the refractive index of the adhesive layer was in the range of 1.47 to 1.50, and the adhesiveness, reworkability, and Durability is also excellent. That is, the adhesive films of Examples 1 to 5 can satisfy the required requirements and can overcome the problems existing in the prior art. Further, the adhesive films of Examples 3 to 5 had a surface resistivity of 5.0 × 10 ^{+ 10} Ω / □ or less, and the surface resistivity was sufficient for providing antistatic properties.

The adhesive film of Comparative Example 1 had a high gel fraction and a low initial adhesion of the adhesive layer having a thickness of 20 μm. Further, since the (meth) acrylate monomer having an aryl group is not contained, the refractive index of the adhesive layer is low. Moreover, the adhesion and durability are also poor.

The adhesive film of Comparative Example 2 had a low gel fraction and a low adhesion of the adhesive layer having a thickness of 5 μm. Further, since the (meth) acrylate monomer having an aryl group is not contained, the refractive index of the adhesive layer is low. Moreover, adhesion, reworkability, and durability are also poor.

The adhesive film of Comparative Example 3 had a low gel fraction, poor reworkability, and durability.

As described above, the adhesive films of Comparative Examples 1 to 3 could not satisfy the conventionally proposed requirements and overcome the problems existing in the past.

Claims (10)

An adhesive layer in a pressure-sensitive adhesive layer obtained by crosslinking an adhesive composition comprising an acrylic polymer, which is a (meth) acrylate monomer having a main component and other copolymerization a copolymer of a monomer; the (meth) acrylate monomer as the main component includes at least one of an alkyl (meth) acrylate monomer having an alkyl group having a C1 to C14 carbon number; And at least one or more of the aryl group-containing (meth) acrylate monomers; and the other copolymerizable monomer includes at least one of a nitrogen atom-containing vinyl monomer, and a hydroxyl group-containing copolymerization property At least one or more of vinyl monomers; and the crosslinking agent that crosslinks the adhesive composition is a trifunctional isocyanate compound; the thickness of the adhesive layer is from 1 μm to 20 μm, and when the thickness is 20 μm, The initial adhesive strength is 3.0 (N/25 mm) or more, and the refractive index is 1.47 to 1.50; the acrylic polymer does not include a carboxyl group-containing copolymerizable vinyl monomer; and the bonded body is formed by lamination Before the adhesive layer of the adhesive layer, After the aging treatment is performed, after the adhesive film on which the adhesive layer is formed is attached to the adherend, it is not necessary to carry out aging treatment. The adhesive layer according to claim 1, wherein the adhesive composition comprises: a copolymer having a weight average molecular weight of 200,000 to 2,000,000, and the copolymer is 70 to 95 parts by weight relative to (A) At least one or more of alkyl (meth) acrylate monomers having an alkyl group having from C1 to C14, and from 5 to 30 parts by weight of (B) aryl group-containing 100 parts by weight of at least one of the (meth) acrylate monomers, having 2 to 50 parts by weight of one or more of (C) nitrogen-containing vinyl monomers, and 0.1 to 10 parts by weight At least one of (D) a hydroxyl group-containing copolymerizable vinyl monomer; and 0.001 to 1 part by weight of the (E) trifunctional isocyanate compound. The adhesive layer according to claim 1 or 2, wherein the adhesive layer has a gel fraction of 50% to 70%. The adhesive layer according to claim 1 or 2, wherein the adhesive composition contains 0.1 to 5.0 parts by weight of an ionic compound having a melting point of 25 ° C to 50 ° C, and the surface resistivity of the adhesive layer is 5.0. ×10 ⁺¹⁰ Ω/□ or less. An adhesive film comprising the adhesive layer according to any one of claims 1 to 4 formed on one surface of the release film, and having a release film/adhesive layer/release film. An adhesive film in which the adhesive layer according to any one of claims 1 to 4 is laminated on one surface of a substrate. A film for polarizing plate and display panel bonding, which uses the adhesive film described in claim 5. A film for a touch panel using the adhesive film described in claim 5. A film for electronic paper using the adhesive film of claim 5. An optical film having an adhesive layer, wherein the adhesive layer according to any one of claims 1 to 4 is laminated on at least one surface of the optical film.