JP7172409B2 - Adhesive composition and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition, and more particularly to a pressure-sensitive adhesive composition suitable for use in attaching touch panel members.

Adhesives (also referred to as pressure-sensitive adhesives) are processed into forms such as tapes and labels, and are used in a wide range of applications. In addition, it is applied to various substances such as plastics, papers, metals, glass, and pottery as objects to be adhered.
On the other hand, with the recent rapid progress in electronics technology, various flat panel displays (FPDs) such as liquid crystal displays (LCDs) and plasma display panels (PDPs) have come to be used as display devices in various fields. rice field.
These display devices generally have a laminated structure in which transparent plastic materials such as glass or polycarbonate are laminated with an adhesive. In such applications, adhesives must have transparency that does not impair the visibility of glass, transparent plastic substrates, optical films, etc., as well as durability under severe conditions of high temperature or high temperature and high humidity. Even after the test, it is required that no peeling or floating from the substrate interface occurs.
In addition, whitening may occur due to intrusion of moisture from the outside, and there is a demand for improvement of this phenomenon.

Various pressure-sensitive adhesive compositions have been proposed to solve the above problems.
For example, Patent Document 1 discloses a pressure-sensitive adhesive composition containing a high-molecular-weight acrylic polymer and a low-molecular-weight acrylic polymer from the viewpoint of heat resistance. These pressure-sensitive adhesive compositions suppress lifting and peeling under high-temperature and high-humidity conditions by combining acrylic polymers with different molecular weights.
Patent Document 2 discloses that a pressure-sensitive adhesive composition containing a specific vinyl polymer and an acrylic pressure-sensitive adhesive polymer can prevent lifting and peeling after high-humidity loading even when a plastic substrate is used as an adherend. is disclosed.
Further, Patent Document 3 discloses an excellent optical sheet exhibiting excellent adhesiveness to optical members by setting the dielectric constant at a frequency of 1 MHz and the adhesiveness to glass within specific ranges. .

JP 2012-41453 A JP 2014-88549 A JP 2012-140605 A

However, the demand for heat resistance (durability) and whitening prevention tends to increase more and more. For example, in the field of optical laminates such as displays, there is It is desired to suppress the foaming phenomenon as much as possible.
According to the adhesive compositions described in Patent Documents 1 to 3, although a certain effect is seen in suppressing floating and peeling of the adhesive under high temperature and high humidity conditions, the peel strength to glass is insufficient, There is room for improvement in terms of preventing whitening and suppressing fine foaming.
An object of the present invention is to provide a pressure-sensitive adhesive composition that has a high relative dielectric constant, high adhesion to glass, and excellent whitening resistance.

As a result of intensive studies in view of the above problems, the present inventors have found that a pressure-sensitive adhesive composition containing a specific acrylic pressure-sensitive adhesive polymer has high adhesive strength to glass and is excellent in whitening resistance. The present inventors have found that it is a product, and have completed the present invention.
That is, the present invention is as follows.

[1] A glass transition temperature (Tg) of −80° C. to 10° C., a number average molecular weight (Mn) of 80,000 to 1,000,000, and a weight average molecular weight (Mw)/number average molecular weight A pressure-sensitive adhesive composition containing an acrylic pressure-sensitive adhesive polymer having a (Mn) ratio of 1.05 to 3.0,
Alkoxyalkyl acrylate and/or methyl acrylate are included as monomers constituting the acrylic adhesive polymer, and the total amount of the alkoxyalkyl acrylate and methyl acrylate is the total amount of the acrylic adhesive polymer. A pressure-sensitive adhesive composition in the range of 60 to 99% by mass of the constituent monomers.
[2] The alkoxyalkyl acrylate is at least one selected from the group consisting of 2-methoxymethyl acrylate, 2-ethoxymethyl acrylate, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate. Item 1. The pressure-sensitive adhesive composition according to item 1.
[3] The pressure-sensitive adhesive composition according to [1] or [2], which contains the acrylic pressure-sensitive adhesive polymer and a cross-linking agent.
[4] The method for producing an adhesive composition according to any one of [1] to [3], wherein the acrylic adhesive polymer is a polymer produced by living radical polymerization.

According to the pressure-sensitive adhesive composition of the present invention, since it has a high dielectric constant, the sensitivity of the touch panel is improved, and it has a high peel strength to glass, and has excellent transparency (whitening resistance). you get something.

The present invention will be described in detail below. In this specification, "(meth)acryl" means acryl and/or methacryl.

The pressure-sensitive adhesive composition according to the present invention contains the acrylic pressure-sensitive adhesive polymer described below.

The acrylic adhesive polymer in the present invention is a polymer having a glass transition temperature (Tg) of -80 to 10°C, more preferably a Tg in the range of -60 to 0°C, and a range of -60 to -20°C. is more preferred. In the present invention, a value measured by differential scanning calorimetry (DSC) at a heating rate of 10° C./min is adopted as Tg. If the Tg is less than −80° C., the cohesive strength of the resulting pressure-sensitive adhesive may be insufficient and the durability may be poor. On the other hand, if the temperature exceeds 10°C, step conformability and adhesive strength at low temperatures may not be sufficient.

The acrylic adhesive polymer has a number average molecular weight (Mn) of 80,000 to 1,000,000, preferably 80,000 to 600,000, more preferably 80,000 to 300,000. .
If the Mn exceeds 1,000,000, the conformability to irregularities tends to decrease, and handling in manufacturing becomes difficult. On the other hand, if the Mn is less than 80,000, sufficient cohesive strength and good adhesiveness cannot be exhibited.
Furthermore, the acrylic adhesive polymer preferably has a weight average molecular weight (Mw) of 100,000 or more, more preferably 250,000 or more, from the viewpoint of exhibiting sufficient cohesion and good adhesion. is more preferable, and 400,000 or more is even more preferable.
On the other hand, if the weight-average molecular weight is too high, the conformability to irregularities tends to decrease, and handling in production becomes difficult. Therefore, the upper limit is preferably 2,000,000 or less, more preferably 1,000,000 or less, and even more preferably 500,000 or less.

Further, the molecular weight distribution (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is 1.05 to 3.0, preferably 2.5 or less, and 2.2 or less. is more preferable, and 2.0 or less is even more preferable. When Mw/Mn is 1.05 to 3.0, cohesion is high and good adhesiveness is exhibited.
Here, the number average molecular weight Mn is a standard polystyrene conversion value obtained using gel permeation chromatography (GPC).

The monomer constituting the acrylic adhesive polymer includes alkoxyalkyl acrylate and/or methyl acrylate, and the total amount of the alkoxyalkyl acrylate and methyl acrylate constitutes the acrylic adhesive polymer. It is in the range of 60 to 99 mass % of the total monomers. It is preferably in the range of 65 to 99% by mass, more preferably in the range of 70 to 98% by mass. When the content is 60% by mass or more, the dielectric constant becomes high and the touch panel sensitivity becomes good.
Furthermore, the amount of alkoxyalkyl acrylate is preferably in the range of 60 to 99% by mass, more preferably 70 to 98% by mass. When the amount of the alkoxyalkyl acrylate is 60% by mass or more, the dielectric constant is high and the hydrophilicity is high, so the whitening resistance is improved.

Examples of the alkoxyalkyl acrylate include 2-methoxymethyl acrylate, 2-ethoxymethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-(n-propoxy)ethyl acrylate, acrylic 2-(n-butoxy)ethyl acid, 3-methoxypropyl acrylate, 3-ethoxypropyl acrylate, 2-(n-propoxy)propyl acrylate, 2-(n-butoxy)propyl acrylate and the like.
Among these, 2-methoxymethyl acrylate, 2-ethoxymethyl acrylate, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are preferred, and 2-methoxyethyl acrylate is preferred from the viewpoint of whitening resistance and cost. Especially preferred.

Examples of monomers constituting the acrylic adhesive polymer include alkoxyalkyl acrylates and methyl acrylates, as well as alkyl (meth)acrylates having an alkyl group of 4 to 12 carbon atoms.

Examples of (meth)acrylic acid alkyl esters having an alkyl group having 4 to 12 carbon atoms include n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, and (meth)acrylic acid. n-octyl acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, (meth)acrylate Examples include lauryl acrylate, and preferred monomers include n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, (meth) ) n-nonyl acrylate, isononyl (meth)acrylate and the like.

In addition to the (meth)acrylic acid alkyl ester having an alkyl group of 4 to 12 carbon atoms, other monomers copolymerizable therewith can be used as long as the adhesion performance is not impaired.
Examples of copolymerizable monomers include α,β-ethylenically unsaturated carboxylic acid monomers such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid; ) Alkyl (meth)acrylate having an alkyl group of 1 to 3 carbon atoms such as n-propyl acrylate and isopropyl (meth)acrylate; Vinyl aromatic monomers such as styrene, α-methylstyrene and vinyltoluene cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, and other aliphatic ring-based vinyl monomers Monoalkyl esters of unsaturated dicarboxylic acids such as itaconic acid monoethyl ester and fumaric acid monobutyl ester; (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 4 - hydroxyl group-containing monomers such as hydroxybutyl, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate and polyethylene-polypropylene glycol mono (meth) acrylate; acrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N- ethylenically unsaturated carboxylic acid amides such as methoxybutylacrylamide and N-substituted compounds; unsaturated alcohols such as allyl alcohol; (meth)acrylonitrile, vinyl acetate, glycidyl (meth)acrylate, diacetone acrylamide, etc. One or more of these can be used.

The acrylic pressure-sensitive adhesive polymer having a narrow molecular weight distribution as described above is not subject to any particular restrictions, and can be produced by a known production method. Examples thereof include a method using various controlled polymerization methods such as living radical polymerization and living anion polymerization, a reprecipitation method, and a method of separation by chromatography. Among these, living radical polymerization is preferable from the viewpoint of simple operation and adaptability to a wide range of monomers.

Living radical polymerization may employ any process such as a batch process, a semi-batch process, a dry continuous polymerization process, a continuous stirred tank process (CSTR), and the like. Moreover, the polymerization system can be applied to various modes such as bulk polymerization without solvent, solvent-based solution polymerization, water-based emulsion polymerization, mini-emulsion polymerization, and suspension polymerization.
The type of living radical polymerization method is not particularly limited, and reversible addition-fragmentation chain transfer polymerization method (RAFT method), nitroxy radical method (NMP method), atom transfer radical polymerization method (ATRP method), organic tellurium compound. (TERP method), a polymerization method using an organic antimony compound (SBRP method), a polymerization method using an organic bismuth compound (BIRP method), and an iodine transfer polymerization method. Among these, the RAFT method, the NMP method and the ATRP method are preferred from the viewpoint of controllability of polymerization and simplicity of implementation.

In the RAFT method, controlled polymerization proceeds via reversible chain transfer reactions in the presence of specific polymerization control agents (RAFT agents) and general free-radical polymerization initiators. As the RAFT agent, various known RAFT agents such as dithioester compounds, xanthate compounds, trithiocarbonate compounds and dithiocarbamate compounds can be used. A monofunctional RAFT agent having only one active site may be used, or a bifunctional or higher functional RAFT agent may be used.
In addition, the amount of the RAFT agent used is appropriately adjusted depending on the type of the monomer and RAFT agent used.

As the polymerization initiator used in the polymerization by the RAFT method, known radical polymerization initiators such as azo compounds, organic peroxides and persulfates can be used. Azo compounds are preferred because side reactions are less likely to occur. Specific examples of the azo compounds include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(4-methoxy-2, 4-dimethylvaleronitrile), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1- carbonitrile), 2,2′-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2′-azobis(N-butyl-2-methylpropionamide) and the like. The above radical polymerization initiators may be used alone or in combination of two or more.

The ratio of the radical polymerization initiator used is not particularly limited, but from the viewpoint of obtaining a polymer with a smaller molecular weight distribution, the amount of the radical polymerization initiator used per 1 mol of the RAFT agent is preferably 0.5 mol or less. .2 mol or less is more preferable.
From the viewpoint of stably conducting the polymerization reaction, the lower limit of the amount of the radical polymerization initiator to be used per 1 mol of the RAFT agent is 0.01 mol. Therefore, the amount of the radical polymerization initiator used relative to 1 mol of the RAFT agent is preferably 0.01 mol or more and 0.5 mol or less, more preferably 0.05 mol or more and 0.2 mol or less.

The reaction temperature during the polymerization reaction by the RAFT method is preferably 40°C or higher and 100°C or lower, more preferably 45°C or higher and 90°C or lower, and still more preferably 50°C or higher and 80°C or lower. If the reaction temperature is 40° C. or higher, the polymerization reaction can proceed smoothly.
On the other hand, if the reaction temperature is 100° C. or lower, side reactions can be suppressed, and restrictions on usable initiators and solvents are relaxed.

In the NMP method, a specific nitroxide-containing alkoxyamine compound or the like is used as a living radical polymerization initiator, and polymerization proceeds via nitroxide radicals derived therefrom. In the present disclosure, the type of nitroxide radical to be used is not particularly limited, and commercially available nitroxide-based polymerization initiators can be used. From the viewpoint of controllability of polymerization when a monomer containing acrylate is polymerized, it is preferable to use a compound represented by the following general formula (3) as the nitroxide compound.

（式中、Ｒ¹は炭素数１～２のアルキル基又は水素原子であり、Ｒ²は炭素数１～２のアルキル基又はニトリル基であり、Ｒ³は－（ＣＨ₂）_m－、ｍは０～２であり、Ｒ⁴、Ｒ⁵は炭素数１～４のアルキル基である。）

(wherein R ¹ is an alkyl group having 1 to 2 carbon atoms or a hydrogen atom, R ² is an alkyl group having 1 to 2 carbon atoms or a nitrile group, and R ³ is --(CH ₂ ) _m --, m is 0 to 2, and R ⁴ and R ⁵ are alkyl groups having 1 to 4 carbon atoms.)

The nitroxide compound represented by the general formula (3) undergoes primary dissociation by heating at about 70 to 80° C., and undergoes an addition reaction with the vinyl monomer. In this case, a polyfunctional polymerization precursor can be obtained by adding a nitroxide compound to a vinyl-based monomer having two or more vinyl groups.
Then, the vinyl-based monomer can be subjected to living polymerization by subjecting the polymerization precursor to secondary dissociation under heating. In this case, since the polymerization precursor has two or more active sites in the molecule, a polymer with a narrower molecular weight distribution can be obtained. In addition, the amount of the nitroxide compound used is appropriately adjusted depending on the type of the monomer and nitroxide compound used.

Polymerization may be carried out by adding 0.001 to 0.2 mol of the nitroxide radical represented by general formula (4) to 1 mol of the nitroxide compound represented by general formula (3).

(In the formula, R ⁶ and R ⁷ are alkyl groups having 1 to 4 carbon atoms.)

By adding 0.001 mol or more of the nitroxide radical represented by the general formula (4), the time required for the nitroxide radical concentration to reach a steady state is shortened. This makes it possible to control the polymerization to a higher degree and obtain a polymer with a narrower molecular weight distribution.
On the other hand, if the amount of the nitroxide radical added is too large, the polymerization may not proceed. A more preferable addition amount of the nitroxide radical to 1 mol of the nitroxide compound is in the range of 0.01 to 0.5 mol, and a more preferable addition amount is in the range of 0.05 to 0.2 mol.

The reaction temperature in the NMP method is preferably 50°C or higher and 140°C or lower, more preferably 60°C or higher and 130°C or lower, still more preferably 70°C or higher and 120°C or lower, and particularly preferably 80°C or higher and 120°C. It is below. If the reaction temperature is 50° C. or higher, the polymerization reaction can proceed smoothly. On the other hand, if the reaction temperature is 140° C. or lower, side reactions such as radical chain transfer tend to be suppressed.

In the ATRP method, a polymerization reaction is generally carried out using an organic halide as an initiator and a transition metal complex as a catalyst. The organic halide used as the initiator may be monofunctional or bifunctional or higher. Bromides and chlorides are preferred as types of halogens.

The reaction temperature in the ATRP method is preferably 20°C or higher and 200°C or lower, more preferably 50°C or higher and 150°C or lower. If the reaction temperature is 20° C. or higher, the polymerization reaction can proceed smoothly.

In the production of the acrylic adhesive polymer in the present invention, a known polymerization solvent can be used in living radical polymerization. Specifically, aromatic compounds such as benzene, toluene, xylene, and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone compounds such as acetone and methyl ethyl ketone; alcohol, water, and the like. Alternatively, bulk polymerization or the like may be performed without using a polymerization solvent.

The pressure-sensitive adhesive composition of the present invention contains, in addition to the acrylic pressure-sensitive adhesive polymer, if necessary, a cross-linking agent (curing agent), a tackifier, a plasticizer, an antioxidant, an ultraviolet absorber, an anti-aging agent, The composition may also contain additives such as flame retardants, fungicides, silane coupling agents, fillers and colorants.
Among these components, it is preferable to add a cross-linking agent (curing agent) to the pressure-sensitive adhesive composition of the present invention from the viewpoint of ensuring adhesive physical properties such as adhesiveness and cohesiveness.

Examples of the crosslinking agent (curing agent) include a glycidyl compound having two or more glycidyl groups, an isocyanate compound having two or more isocyanate groups, an aziridine compound having two or more aziridinyl groups, an oxazoline compound having an oxazoline group, and a metal chelate compound. , butylated melamine compounds, and the like. Among these, aziridine compounds, glycidyl compounds and isocyanate compounds are preferred.

Examples of the aziridine compound include 1,6-bis(1-aziridinylcarbonylamino)hexane, 1,1′-(methylene-di-p-phenylene)bis-3,3-aziridyl urea, 1,1′- (Hexamethylene)bis-3,3-aziridyl urea, ethylenebis-(2-aziridinylpropionate), tris(1-aziridinyl)phosphine oxide, 2,4,6-triaziridinyl-1,3,5- triazine, trimethylolpropane-tris-(2-aziridinylpropionate) and the like.

Examples of the glycidyl compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl. ether, tetraglycidylxylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like. Functional glycidyl compounds are included.

As the isocyanate compound, a compound having two or more isocyanate groups is preferably used.
As the isocyanate compound, various aromatic, aliphatic, and alicyclic isocyanate compounds, and modified products (prepolymers, etc.) of these isocyanate compounds can be used.

Examples of the aromatic isocyanate include diphenylmethane diisocyanate (MDI), crude diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and tolidine diisocyanate (TODI).
Aliphatic isocyanates include hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), lysine triisocyanate (LTI) and the like.
Alicyclic isocyanates include isophorone diisocyanate (IPDI), cyclohexyl diisocyanate (CHDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI) and the like.
Examples of modified isocyanates include urethane-modified, dimer, trimer, carbodiimide-modified, allophanate-modified, biuret-modified, urea-modified, isocyanurate-modified, oxazolidone-modified, and isocyanate-modified isocyanate compounds. group-terminated prepolymers, and the like.

When the pressure-sensitive adhesive composition of the present invention contains a cross-linking agent (curing agent), the content thereof is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer, and more It is preferably 0.03 to 5 parts by mass, more preferably 0.05 to 2 parts by mass.

Examples of the tackifier include rosin derivatives such as rosin ester, gum rosin, tall oil rosin, hydrogenated rosin ester, maleated rosin, and disproportionated rosin ester; terpene phenol resin, α-pinene, β-pinene, limonene, etc. (hydrogenated) petroleum resin; coumarone-indene resin; hydrogenated aromatic copolymer; styrene resin; phenolic resin; xylene resin; .

Examples of the plasticizer include phthalates such as di-n-butyl phthalate, di-n-octyl phthalate, bis(2-ethylhexyl) phthalate, di-n-decyl phthalate, and diisodecyl phthalate; Adipates such as n-octyl adipate; Sebacates such as bis(2-ethylhexyl) sebacate and di-n-butyl sebacate; Azelaates such as bis(2-ethylhexyl) azelate; Paraffins such as chlorinated paraffin Glycols such as polypropylene glycol; Epoxy-modified vegetable oils such as epoxidized soybean oil and epoxidized linseed oil; Phosphates such as trioctyl phosphate and triphenyl phosphate; Phosphites such as triphenyl phosphite ; Ester oligomers such as esters of adipic acid and 1,3-butylene glycol; Low molecular weight polymers such as low molecular weight polybutene, low molecular weight polyisobutylene, and low molecular weight polyisoprene; Oils such as process oil and naphthenic oil etc.

Examples of the antioxidant include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β-(3,5- Di-tert-butyl-4-hydroxyphenyl)propionate, 2,2′-methylenebis(4-methyl-6-tert-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4 , 4′-thiobis(3-methyl-6-tert-butylphenol), 4,4′-butylidenebis(3-methyl-6-tert-butylphenol), 3,9-bis[1,1-dimethyl-2-[ β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3-tris(2-methyl -4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis-[ methylene-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate]methane, bis[3,3′-bis-(4′-hydroxy-3′-tert-butylphenyl) butyric acid] glycol ester, 1,3,5-tris(3′,5′-di-tert-butyl-4′-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H ) Phenolic antioxidants such as trione and tocopherols; Sulfur-based antioxidants such as dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and stearyl 3,3'-thiodipropionate Inhibitors; triphenyl phosphite, diphenyl isodecyl phosphite, 4,4′-butylidene-bis(3-methyl-6-tert-butylphenylditridecyl) phosphite, cyclic neopentanetetrayl bis(octadecyl phosphite ), tris(nonylphenyl)phosphite, tris(monononylphenyl)phosphite, tris(dinonylphenyl)phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene -10-oxide, 10-(3,5-di-tert-butyl-4-hydroxybenzyl)-9,1 0-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, tris(2,4-di-tert-butylphenyl ) phosphite, cyclic neopentanetetraylbis(2,4-di-tert-butylphenyl)phosphite, cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl)phosphite Phosphorus antioxidants such as phyto, 2,2-methylenebis(4,6-di-tert-butylphenyl)octylphosphite and the like.

Examples of the ultraviolet absorber include salicylic acid-based ultraviolet absorbers such as phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate; 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy -4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4- Benzophenone UV absorbers such as methoxy-5-sulfobenzophenone, bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane; 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl)benzotriazole, 2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)benzotriazole, 2-(2′-hydroxy-3 '-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-( 2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, 2-[2'-hydroxy-3'- (3″,4″,5″,6″-tetrahydrophthalimidomethyl)-5′-methylphenyl]benzotriazole, 2,2-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6 -(2H-benzotriazol-2-yl)phenol], 2-(2′-hydroxy-5′-methacryloxyphenyl)-2H-benzotriazole, 2,2′-methylenebis[4-(1,1,3 ,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol] benzotriazole-based UV absorbers; 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate, ethyl-2 -Cyanoacrylate UV absorbers such as cyano-3,3'-diphenylacrylate; nickel bis(octylphenyl) sulfide, [2,2'-thiobis(4-tert-octylphenolate)]-n-butylamine nickel, Nickel complex-3,5-di -tert-butyl-4-hydroxybenzyl-phosphate monoethylate, nickel-based UV stabilizers such as nickel-dibutyldithiocarbamate, and the like.

The anti-aging agents include poly(2,2,4-trimethyl-1,2-dihydroquinoline), 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, 1-(N-phenyl amino)-naphthalene, styrenated diphenylamine, dialkyldiphenylamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-di-2-naphthyl-p -phenylenediamine, 2,6-di-tert-butyl-4-methylphenol, mono(α-methylbenzyl)phenol, di(α-methylbenzyl)phenol, tri(α-methylbenzyl)phenol, 2,2' -methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(6-tert-butyl-3-methylphenol) , 4,4′-thiobis(6-tert-butyl-3-methylphenol), 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,5-di-tert-butylhydroquinone, 2,5-di- tert-amylhydroquinone, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, nickel dibutyldithiocarbamate, tris(nonylphenyl)phosphite, dilauryl thiodipropionate, thiodipropionic acid and distearyl.

Examples of the flame retardant include tetrabromobisphenol A, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, hexabromobenzene, tris(2,3-dibromopropyl)isocyanurate, 2,2- Halogen flame retardants such as bis(4-hydroxyethoxy-3,5-dibromophenyl)propane, decabromodiphenyl oxide, and halogen-containing polyphosphate; ammonium phosphate, tricresyl phosphate, triethyl phosphate, tris(β-chloroethyl ) phosphorus-based flame retardants such as phosphate, trischloroethyl phosphate, trisdichloropropyl phosphate, cresyldiphenyl phosphate, xylenyldiphenyl phosphate, acidic phosphoric acid esters, nitrogen-containing phosphorus compounds; red phosphorus, tin oxide, antimony trioxide, Inorganic flame retardants such as zirconium hydroxide, barium metaborate, aluminum hydroxide, and magnesium hydroxide; poly(dimethoxysiloxane), poly(diethoxysiloxane), poly(diphenoxysiloxane), poly(methoxyphenoxysiloxane), methyl Examples include siloxane-based flame retardants such as silicate, ethyl silicate, and phenyl silicate.

Examples of the fungicide include benzimidazole, benzothiazole, trihaloallyl, triazole, and organic nitrogen-sulfur compounds.

Examples of the silane coupling agent include vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycid. xypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- β (aminoethyl)-γ-aminopropyltrimethoxysilane and the like.

Examples of the filler include inorganic powder filler such as calcium carbonate, titanium oxide, mica and talc; fibrous filler such as glass fiber and organic reinforcing fiber.

The form of the pressure-sensitive adhesive composition of the present invention is not particularly limited as long as it contains an acrylic pressure-sensitive adhesive polymer. For example, it may be used in the form of a solvent-type pressure-sensitive adhesive composition dissolved in an organic solvent such as ethyl acetate, or in the form of an emulsion-type pressure-sensitive adhesive composition in which an acrylic pressure-sensitive adhesive polymer and a tackifier are dispersed in an aqueous medium. may be used as
In the case of the solution-type pressure-sensitive adhesive composition and the emulsion-type pressure-sensitive adhesive composition, the amount of a medium such as an organic solvent or water used is usually 20 to 80 parts by weight per 100 parts by weight of the pressure-sensitive adhesive composition.

When used as an emulsion-type pressure-sensitive adhesive, a stabilizer may be added. Examples of stabilizers include cadmium stearate, zinc stearate, barium stearate, calcium stearate, lead dibutyltin dilaurate, tris(nonylphenyl)phosphite, triphenylphosphite, diphenylisodecylphosphite, and other polyvinyl chloride stabilizers. Stabilizer; di-n-octyltin bis(isooctylthioglycolic acid ester) salt, di-n-octyltin maleate polymer, di-n-octyltin dilaurate, di-n-octyltin maleate ester salt, di-n-butyltin bismaleate ester salt, di-n-butyltin maleate polymer, di-n-butyltin bisoctylthioglycol ester salt, di-n-butyltin β-mercaptopropionate polymer, di -n-butyltin dilaurate, di-n-methyltin bis(isooctyl mercaptoacetate) salt, poly(thiobis-n-butyltin sulfide), monooctyltin tris(isooctylthioglycolic acid ester), dibutyltin maleate, di-n- Organotin stabilizers such as butyltin malate ester/carboxylate and di-n-butyltin malate ester/mercaptide; tribasic lead sulfate, dibasic lead phosphite, basic lead sulfite, dibasic phthalate Lead-based stabilizers such as acid lead, lead silicate, dibasic lead stearate, and lead stearate; metals such as cadmium-based soap, zinc-based soap, barium-based soap, lead-based soap, composite metal soap, and calcium stearate Examples include soap-based stabilizers.

Further, the pressure-sensitive adhesive composition of the present invention is a composition containing an acrylic pressure-sensitive adhesive polymer, a monofunctional and/or polyfunctional (meth)acrylic acid-based monomer, a photopolymerization initiator, etc. Alternatively, it may be used in the form of a so-called syrup-type photocurable pressure-sensitive adhesive composition that is cured by actinic energy rays such as ultraviolet rays.

In the case of a photocurable pressure-sensitive adhesive composition, the composition may contain an organic solvent or the like, but it is generally used as a solvent-free composition that does not contain solvents.

Examples of the monofunctional (meth)acrylic acid-based monomers include (meth)acrylic acid alkyl esters having an alkyl group having 1 to 12 carbon atoms; cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, ( (Meth)acrylic acid esters having a cyclic structure such as isobornyl methacrylate; hydroxy(meth)acrylates such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate; Alkyl esters; (meth)acrylic acid and the like. These compounds may be used alone or in combination of two or more.

Examples of the polyfunctional (meth)acrylic acid-based monomers include alkylene glycol di(meth)acrylates such as butanediol di(meth)acrylate and hexanediol di(meth)acrylate; triethylene glycol di(meth)acrylates; Di(meth)acrylates of polyalkylene glycol such as acrylates; trimethylolpropane tri(meth)acrylate and its ethylene oxide and/or propylene oxide modified products, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc. is mentioned. In addition, polymers (macromonomers) having (meth)acryloyl groups such as polyurethane (meth)acrylates and polyisoprene-based (meth)acrylates can also be used. Specific compounds of polyisoprene-based (meth)acrylates include, for example, esters of maleic anhydride adducts of isoprene polymers and 2-hydroxyethyl methacrylate. These compounds may be used alone or in combination of two or more.

Examples of the photopolymerization initiator include benzoin and its alkyl ethers, acetophenones, anthraquinones, thioxanthones, ketals, benzophenones, xanthones, acylphosphine oxides, α-diketones and the like.
A photosensitizer can also be used in combination to improve the sensitivity to active energy rays.
Examples of photosensitizers include benzoic acid-based and amine-based photosensitizers. These can also be used in combination of two or more.
The amount of the photoinitiator and photosensitizer used is preferably 0.01 to 10 parts by weight per 100 parts by weight of the monofunctional and/or polyfunctional (meth)acrylic acid-based monomer.

The pressure-sensitive adhesive composition of the present invention is suitably used for lamination when forming laminates such as various optical films, in addition to various general adhesive processed products such as pressure-sensitive adhesive films, pressure-sensitive adhesive sheets, pressure-sensitive adhesive tapes, and labels. be able to.

When applying to the general adhesive processed product, after coating the adhesive composition of the present invention on one or both sides of various substrates, the adhesive layer is formed by drying or irradiating active energy rays such as UV, Adhesive products such as adhesive sheets or adhesive tapes can be used. A product having an adhesive layer can also be obtained by melting the composition, coating it on a substrate, and then cooling it.
As the base material, paper, film, cloth, non-woven fabric, metal foil, etc. can be used, and the adhesive composition may be applied directly onto these base materials, or may be applied to release paper or the like. It may be transferred to the substrate after being processed and dried.
The thickness of the pressure-sensitive adhesive formed on the pressure-sensitive adhesive sheet (film thickness after drying) is selected depending on the application, but is usually in the range of 1 to 300 μm, preferably in the range of 5 to 250 μm, and more preferably in the range of 10 to 200 μm. preferable.

Specific examples of the general adhesive products include adhesive sheets, adhesive films, adhesive tapes, pressure-sensitive tapes, surface protective films, surface protective tapes, masking tapes, electrical insulation tapes, laminates, and the like.

The pressure-sensitive adhesive composition of the present invention is excellent in transparency and wet heat whitening resistance, and has high tack and adhesive strength to various adherends such as glass. It is also suitable for laminating displays such as display devices and plasma display panels, and various optical films used therein. It is also useful for bonding electronic parts such as flexible printed circuit boards.

(Synthesis Example 1: Production of polymer A-1)
0.79 g of dibenzyltrithiocarbonate (hereinafter also referred to as “DBTTC”) and 2,2′-azobis-2-methylbutyronitrile (hereinafter also referred to as “ABN-E”) were placed in a 1 L flask equipped with a stirrer and thermometer. ) 0.10 g, 475 g of methoxyethyl acrylate (hereinafter also referred to as “MEA”), 14.7 g of hydroxyethyl acrylate (hereinafter also referred to as “HEA”), and 200 g of ethyl acetate were charged and thoroughly desorbed by nitrogen bubbling. Then, polymerization was started in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. As for the molecular weight of the obtained acrylic polymer, Mn was 144,000 and Mw/Mn was 1.60 by GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 2: Production of polymer A-2)
0.73 g of DBTTC, 0.10 g of ABN-E, 466 g of MEA, 24.5 g of HEA and 200 g of ethyl acetate were charged in a 1 L flask equipped with a stirrer and a thermometer, deaerated sufficiently by nitrogen bubbling, and placed in a constant temperature bath at 70°C. to initiate polymerization. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 156,000 in Mn and 1.28 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 3: Production of polymer A-3)
In a 1 L flask equipped with a stirrer and a thermometer, 0.76 g of DBTTC, 0.10 g of ABN-E, 441 g of MEA, 24.5 g of butyl acrylate (hereinafter also referred to as "BA"), acrylic acid (hereinafter referred to as "AA" 24.5 g) and 200 g of ethyl acetate were charged, sufficiently degassed by nitrogen bubbling, and polymerization was initiated in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. As for the molecular weight of the obtained acrylic polymer, Mn was 138,000 and Mw/Mn was 1.63 by GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 4: Production of polymer A-4)
A 1 L flask equipped with a stirrer and a thermometer was charged with 1.23 g of DBTTC, 0.16 g of ABN-E, 392 g of MEA, 73.5 g of BA, 24.5 g of HEA, and 200 g of ethyl acetate, and was sufficiently degassed by bubbling nitrogen. , and the polymerization was initiated in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. As for the molecular weight of the obtained acrylic polymer, Mn was 84,000 and Mw/Mn was 1.89 by GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 5: Production of polymer A-5)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.85 g of DBTTC, 0.11 g of ABN-E, 392 g of MEA, 73.5 g of BA, 24.5 g of HEA and 200 g of ethyl acetate, and degassed sufficiently by bubbling nitrogen. Polymerization was initiated in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 110,000 in Mn and 1.95 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 6: Production of polymer A-6)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.37 g of DBTTC, 0.05 g of ABN-E, 392 g of MEA, 73.5 g of BA, 24.5 g of HEA and 200 g of ethyl acetate, and deaerated sufficiently by bubbling nitrogen. Polymerization was initiated in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 250,000 in Mn and 1.92 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 7: Production of polymer A-7)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.11 g of DBTTC, 0.04 g of ABN-E, 392 g of MEA, 73.5 g of BA, 24.5 g of HEA and 200 g of ethyl acetate, and degassed sufficiently by bubbling nitrogen. Polymerization was initiated in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 510,000 in Mn and 2.14 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 8: Production of polymer A-8)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.74 g of DBTTC, 0.10 g of ABN-E, 318 g of MEA, 147 g of BA, 24.5 g of HEA and 200 g of ethyl acetate, and was sufficiently degassed by nitrogen bubbling to 70°C. Polymerization was initiated in a constant temperature bath of . After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 136,000 in Mn and 1.90 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 9: Production of polymer A-9)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.79 g of DBTTC, 0.10 g of ABN-E, 318 g of MEA, 73.5 g of BA, 73.5 g of methyl acrylate (hereinafter also referred to as "MA"), 24.5 g of HEA. 5 g of ethyl acetate and 200 g of ethyl acetate were charged, sufficiently degassed by nitrogen bubbling, and polymerization was initiated in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. As for the molecular weight of the obtained acrylic polymer, Mn was 125,000 and Mw/Mn was 1.92 by GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 10: Production of polymer A-10)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.85 g of DBTTC, 0.11 g of ABN-E, 245 g of MEA, 73.5 g of BA, 147 g of MA, 24.5 g of HEA and 200 g of ethyl acetate, and was thoroughly desorbed by nitrogen bubbling. Then, polymerization was started in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 142,000 in Mn and 1.96 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 11: Production of polymer A-11)
A 1 L flask equipped with a stirrer and a thermometer was charged with 1.00 g of DBTTC, 0.14 g of ABN-E, 73.5 g of BA, 392 g of MA, 24.5 g of HEA and 200 g of ethyl acetate, and degassed sufficiently by bubbling nitrogen. Polymerization was initiated in a constant temperature bath at 70°C. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. As for the molecular weight of the obtained acrylic polymer, Mn was 140,000 and Mw/Mn was 1.89 by GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 12: Production of polymer A-12)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.74 g of DBTTC, 0.10 g of ABN-E, 245 g of MEA, 220 g of BA, 24.5 g of HEA, and 200 g of ethyl acetate, and was sufficiently degassed by nitrogen bubbling. Polymerization was initiated in a constant temperature bath of . After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 136,000 in Mn and 1.87 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 13: Production of polymer A-13)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.74 g of DBTTC, 0.10 g of ABN-E, 147 g of MEA, 318 g of BA, 24.5 g of HEA, and 200 g of ethyl acetate, and was sufficiently degassed by nitrogen bubbling. Polymerization was initiated in a constant temperature bath of . After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 125,000 in Mn and 1.68 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 14: Production of polymer A-14)
0.74 g of DBTTC, 0.10 g of ABN-E, 465 g of BA, 24.5 g of HEA and 200 g of ethyl acetate were charged in a 1 L flask equipped with a stirrer and a thermometer, deaerated sufficiently by nitrogen bubbling, and placed in a constant temperature bath at 70°C. to initiate polymerization. After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 132,000 in Mn and 1.89 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 15: Production of polymer A-15)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.85 g of DBTTC, 0.11 g of ABN-E, 318 g of BA, 147 g of MA, 24.5 g of HEA, and 200 g of ethyl acetate. Polymerization was initiated in a constant temperature bath of . After 6 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. The molecular weight of the obtained acrylic polymer was 145,000 in Mn and 2.06 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 16: Production of polymer A-16)
0.10 g of 2,2′-azobis(2,4-dimethylvaleronitrile) (hereinafter also referred to as “V-65”), 120 g of MEA, 22.5 g of BA, 7 HEA in a 1 L flask equipped with a stirrer and a thermometer. 0.5 g of ethyl acetate and 270 g of ethyl acetate were charged, sufficiently degassed by nitrogen bubbling, and polymerization was initiated in a constant temperature bath at 75°C. After 5 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. According to GPC (gel permeation chromatography) measurement (converted to polystyrene), the obtained acrylic polymer had a molecular weight of Mn of 68,000 and an Mw/Mn of 4.56.

(Synthesis Example 17: Production of polymer A-17)
A 1 L flask equipped with a stirrer and a thermometer was charged with 0.03 g of V-65, 120 g of MEA, 22.5 g of BA, 7.5 g of HEA and 220 g of ethyl acetate, degassed sufficiently with nitrogen bubbling, and placed in a constant temperature bath at 75°C. Polymerization started. After 5 hours, the mixture was cooled to room temperature, and ethyl acetate was added to adjust the solid content concentration to 30%. As for the molecular weight of the obtained acrylic polymer, Mn was 148,000 and Mw/Mn was 5.88 by GPC (gel permeation chromatography) measurement (converted to polystyrene).

For the polymers A-1 to A-17 obtained above, the number average molecular weight (Mn), weight average molecular weight (Mw) and glass transition temperature (Tg) were measured by the following methods, and the weight average molecular weight (Mw) / number average molecular weight (Mn) ratio was calculated. The results are shown in Table 1.

(Number average molecular weight, weight average molecular weight)
Using a gel permeation chromatograph (model name “HLC-8320”, manufactured by Tosoh Corporation), the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were obtained under the following conditions. Also, the molecular weight distribution (Mw/Mn) was calculated from the obtained values.
○ Measurement conditions Column: TSKgel Super Multipore HZ-M × 4 columns manufactured by Tosoh Corporation Column temperature: 40 ° C.
Eluent: Tetrahydrofuran Detector: RI
Flow rate: 600 μL/min

(Glass-transition temperature)
The glass transition point (Tg) of the resulting polymer was determined from the intersection of the baseline of the heat flux curve obtained using a differential scanning calorimeter and the tangent line at the point of inflection. The heat flux curve was obtained by cooling about 10 mg of the sample to −50° C., holding it for 5 minutes, raising the temperature to 300° C. at a rate of 10° C./min, cooling it to −50° C., holding it for 5 minutes, and heating it at 10° C./min. It was obtained under the condition that the temperature was raised to 350°C at min.
Measuring instrument: DSC6220 manufactured by SII Nano Technology Co., Ltd.
Measurement atmosphere: Nitrogen atmosphere

"Example 1"
The polymer (A-1) obtained in Synthesis Example 1 was dissolved in ethyl acetate to prepare a polymer (A-1) solution having a solid concentration of 30% by mass. To 100 parts by mass of the polymer (A-1) solution was mixed 0.16 part of Taketate D-110N (solid concentration: 75% by mass, manufactured by Mitsui Chemicals, Inc.) as a cross-linking agent to obtain an adhesive composition.
This pressure-sensitive adhesive composition was applied onto a polyethylene terephthalate (hereinafter referred to as “PET”) separator having a thickness of 38 μm so that the thickness after drying would be 50 μm. By drying the adhesive composition at 80 ° C. for 4 minutes, ethyl acetate is removed and a cross-linking reaction is performed, and a PET separator with a thickness of 38 μm having a different peeling force from the separator is laminated, and dried at 40 ° C. for 5 days. By standing still and maturing (aging), a pressure-sensitive adhesive film with a double-sided separator was obtained. The obtained adhesive film was measured for peel strength to glass, whitening resistance and dielectric constant by the following methods, and the results are shown in Tables 2 and 3.

"Example 2" to "Example 12", "Comparative Example 1" to "Comparative Example 6"
In the same manner as in Example 1, polymer A-2 to polymer AA-17 were mixed with the cross-linking agents shown in Tables 2 and 3 below to prepare adhesive compositions (Examples 1 to 12 and Comparative Examples 1 to 6) were obtained (Example 5 without a cross-linking agent). A pressure-sensitive adhesive film was prepared from the obtained pressure-sensitive adhesive composition in the same manner as in Example 1, and the peel strength to glass, whitening resistance and relative dielectric constant of the obtained pressure-sensitive adhesive film were measured by the following methods. The results are shown in Tables 2 and 3.

(Peel strength to glass)
The pressure-sensitive adhesive film sample was transferred to a PET film (100 μm) treated for easy adhesion to obtain a pressure-sensitive adhesive sheet for evaluation. A glass plate (manufactured by Asahi Glass Co., Ltd., Fabricec FL11A, 1 mm thick) is used as the adherend, and the adhesive sheet for the above evaluation is attached, and a tabletop pressure deaerator TBR-200 (manufactured by Chiyoda Electric Industry Co., Ltd.) is used to remove 0. After crimping for 20 minutes under conditions of 5 MPa and 50° C., using a tensile tester Strograph R type (manufactured by Toyo Seiki Co., Ltd.) with a constant temperature bath, the temperature is 23° C. and the peel rate is 300 mm/min. The 180 degree peel strength of the adhesive sheet was measured according to JIS Z-0237 "Adhesive tape/adhesive sheet test method" under the conditions of , and was taken as the peel strength to glass.

(whitening resistance)
Peel off the release film from the adhesive film sample, transfer to an easy-adhesion treated PET film (100 μm), peel off the other release film, laminate a polycarbonate plate to produce a laminate, and easily adhere to one side of the adhesive sheet. A laminate was prepared by bonding the treated PET film (100 μm) and bonding a polycarbonate plate to the other surface, and using a tabletop pressure deaerator TBR-200 (manufactured by Chiyoda Electric Industry Co., Ltd.) 0.5 MPa, A pressure bonding process was performed for 20 minutes under the condition of 50°C. Thereafter, the laminate was placed in a constant temperature and humidity chamber at 85° C. and 85% RH for 24 hours to apply a load. The appearance of the laminate after loading (presence or absence of foaming and degree of whitening) was visually observed with an optical microscope M205C (manufactured by Leica Microsystems) and evaluated according to the following criteria.
(degree of whitening: whitening resistance)
○: Whitening of the adhesive layer is not observed and the transparent state is maintained △: Whitening of the adhesive layer is observed, but the back surface of the laminate can be seen ×: The adhesive layer is whitened and the back surface of the laminate is visible can not see

(relative permittivity)
The relative permittivity of the pressure-sensitive adhesive sheet at a frequency of 10000 Hz was measured in accordance with JIS K 6911 using an apparatus: Agilent Precision Impedance Analyzer 4294 and a fixture: Agilent Dielectric Test Fixture 16451B under an environment of 23°C and 50% RH. did.

Crosslinking agent Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) in Tables 2 and 3
Coronate L (manufactured by Tosoh Corporation)

As shown in Table 2, in the adhesive film samples using the acrylic copolymers of Examples 1 to 12, good adhesive physical properties as touch panel adhesives (peel strength to glass, whitening resistance, high dielectric rate). In contrast, the adhesive film samples using the acrylic copolymers of Comparative Examples 1 to 6 were insufficient in any of the adhesive physical properties.

Further, from the results of Examples 1 to 12, when the acrylic copolymer contains 60 parts by mass or more of alkoxyalkyl acrylate and/or methyl acrylate and has a molecular weight distribution of 3.0 or less, the adhesion properties are further improved. I found that it works.

Claims (4)

A glass transition temperature (Tg) of −80° C. to 10° C., a number average molecular weight (Mn) of 80,000 to 1,000,000, and a weight average molecular weight (Mw)/number average molecular weight (Mn) A pressure-sensitive adhesive composition containing an acrylic pressure-sensitive adhesive polymer having a ratio of 1.05 to 3.0,
As a monomer constituting the acrylic adhesive polymer, the alkoxyalkyl acrylate is included, or the alkoxyalkyl acrylate and methyl acrylate are included, and the total amount of the alkoxyalkyl acrylate and the methyl acrylate is The amount of the alkoxyalkyl acrylate is in the range of 70 to 99% by mass of the total constituent monomers of the acrylic adhesive polymer , and the amount of the alkoxyalkyl acrylate is 70% of the total constituent monomers of the acrylic adhesive polymer. A pressure-sensitive adhesive composition that is ~99% by mass . 2. According to claim 1, wherein said alkoxyalkyl acrylate is at least one selected from the group consisting of 2-methoxymethyl acrylate, 2-ethoxymethyl acrylate, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate. The adhesive composition described. 3. The pressure-sensitive adhesive composition according to claim 1, comprising the acrylic pressure-sensitive adhesive polymer and a cross-linking agent. 4. The method for producing a pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the acrylic pressure-sensitive adhesive polymer is a polymer produced by living radical polymerization.