JP7302159B2 - Tackifier and adhesive composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tackifier that works to improve the adhesive strength of a pressure-sensitive adhesive when blended therein, and to a pressure-sensitive adhesive composition containing the tackifier.

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 and polycarbonate are laminated with an adhesive. For this reason, the adhesive is required to exhibit sufficient adhesive strength to these materials and to be excellent in transparency. Further improvements in strength, adhesion, etc. are desired.

As a conventional technique, Patent Document 1 discloses a pressure-sensitive adhesive composition excellent in adhesiveness, transparency, etc., which does not contain a carboxyl group-containing monomer component and contains an acrylic crosslinked polymer having alkoxyalkyl acrylate as a main monomer. Agent compositions are disclosed. Further, Patent Document 2 describes that an acrylic polymer compound containing an amide group-containing monomer as a constituent monomer is useful as an adhesive composition for a touch panel.

Moreover, for the purpose of increasing the adhesive strength of the adhesive, a pressure-sensitive adhesive composition in which a tackifier is added to the pressure-sensitive adhesive base polymer is also widely known. As tackifiers, for example, rosin-based resins, terpene-based resins, petroleum-based resins, low-molecular-weight acrylic polymers, and the like are known. However, pressure-sensitive adhesive compositions containing tackifiers composed of rosin-based resins, terpene-based resins, or petroleum-based resins sometimes cause problems such as coloring and discoloration. Hydrogenated resins or hydrocarbon resins are sometimes used in order to prevent problems such as coloring, but the compatibility with the acrylic adhesive polymer that is the adhesive base polymer is insufficient. , the transparency may be impaired or the adhesion may be reduced.

Low-molecular-weight acrylic polymers are excellent in terms of compatibility and transparency with acrylic-based adhesive polymers. It is shown.
For example, Patent Document 3 discloses a pressure-sensitive adhesive composition containing a main polymer having a carboxyl group and a low-molecular-weight acrylic polymer having an amino group. Further, in Patent Document 4, a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition containing a polymer having a highly hydrophilic (meth)alkoxyalkyl (meth)acrylate as a main component and a low-molecular-weight acrylic polymer having an amino group or an amide group is disclosed. , and that it is effective for ensuring transparency even under high temperature and high humidity conditions.

JP 2009-79203 A JP 2012-41456 A JP-A-10-310754 Japanese Patent Application Laid-Open No. 2002-327160

However, the pressure-sensitive adhesive compositions described in Patent Documents 1 and 2 do not have sufficient adhesive strength to various adherends such as glass and polycarbonate.
On the other hand, in the adhesive compositions described in Patent Documents 3 and 4, although the adhesive strength is improved, sufficient adhesive strength may not be obtained depending on the adherend, such as low adhesive strength to glass. Some of them are lacking, and improvements are desired.

An object of the present invention is to provide a tackifier that exhibits high transparency and excellent adhesion to various adherends, and a pressure-sensitive adhesive composition containing the tackifier.

As a result of intensive studies in view of the above problems, the present inventors have found that a tackifier containing a vinyl polymer having a glass transition temperature (Tg), a number average molecular weight, and a weight average molecular weight/number average molecular weight ratio within specific ranges and a pressure-sensitive adhesive composition containing the tackifier can achieve both excellent adhesion to various adherends in the room temperature to high temperature range and good transparency, and completed the present invention. came to.

That is, the present invention is as follows.
[1] A glass transition temperature (Tg) of 60 to 200° C., a number average molecular weight of 500 to 20,000, and a weight average molecular weight (Mw)/number average molecular weight (Mn) ratio of 1.05. A tackifier comprising a vinyl polymer (A) that is ~1.30.
[2] The method for producing an adhesion promoter according to [1], wherein the vinyl polymer (A) is a polymer produced by living radical polymerization.
[3] A pressure-sensitive adhesive composition comprising the tackifier according to [1] and an acrylic pressure-sensitive adhesive polymer (B).
[4] The pressure-sensitive adhesive composition according to [3], wherein the pressure-sensitive adhesive composition has a glass transition temperature (Tg) of -80 to 10°C.
[5] In the adhesive layer obtained by applying the adhesive composition to a separator and then drying it, the glass transition temperature (Tg) of the entire adhesive layer is -80 to 10 ° C., and the adhesive The glass transition temperature (Tg) calculated from the surface layer portion obtained by X-ray photoelectron spectroscopy of the layer is 40 ° C. or higher, and the glass transition temperature (Tg) of the surface layer portion is the glass of the entire adhesive layer. The pressure-sensitive adhesive composition according to [3] or [4], which is higher than the transition temperature (Tg) by 30°C or more.

According to the pressure-sensitive adhesive composition containing the tackifier of the present invention, it is possible to obtain high adhesive strength to various adherends in the room temperature to high temperature range while exhibiting sufficient transparency.

The present invention will be described in detail below. In this specification, "(co)polymer" means a homopolymer and/or copolymer, and "(meth)acryl" means acrylic and/or methacrylic.

The tackifier in the present invention has a glass transition temperature (Tg) of 60 to 200° C., a number average molecular weight (Mn) of 500 to 20,000, and a weight average molecular weight (Mw)/number average molecular weight ( Mn) ratio is 1.05 to 1.30.

The vinyl polymer (A) is a polymer having a glass transition temperature (Tg) of 60 to 200°C, preferably 80 to 180°C, more preferably 100 to 150°C.
If the Tg is less than 60°C, the adhesive strength to various adherends may be insufficient under high temperature conditions, resulting in poor durability. never exceed.
In the present invention, the value measured by differential scanning calorimetry (DSC) at a heating rate of 10° C./min is defined as the glass transition temperature (Tg).

The vinyl polymer (A) has a number average molecular weight (Mn) of 500 to 20,000, preferably 3,000 to 15,000, more preferably 5,000 to 12,000.
If the Mn exceeds 20,000, the compatibility with the acrylic adhesive polymer may deteriorate, and in order to produce a polymer with an Mn of less than 500, it is necessary to use a large amount of a polymerization initiator or a chain transfer agent. There is a possibility that productivity will deteriorate.

The weight average molecular weight (Mw)/number average molecular weight (Mn) ratio of the vinyl polymer (A) is 1.05 to 1.30, preferably 1.05 to 1.25, and 1.05. A range of ~1.20 is more preferred. Good adhesive strength is obtained when the Mw/Mn ratio is in the range of 1.05 to 1.30.

As the monomer constituting the vinyl polymer (A), various vinyl-based unsaturated compounds having radical polymerizability can be used. Saturated carboxylic acid, unsaturated acid anhydride, hydroxyl group-containing unsaturated compound, amino group-containing unsaturated compound, amide group-containing unsaturated compound, alkoxyl group-containing unsaturated compound, cyano group-containing unsaturated compound, nitrile group-containing unsaturated compound compounds, maleimide compounds, and the like. These compounds may be used alone or in combination of two or more.
Among these, it is preferable to use (meth)acrylic compounds as the main component from the viewpoint of good compatibility with the acrylic adhesive polymer (B). The amount of the (meth)acrylic compound used is preferably in the range of 10 to 100% by mass, more preferably in the range of 30 to 95% by mass, more preferably 50 to 90% by mass, based on the total monomers constituting the vinyl polymer (A). More preferred is the mass % range.

Examples of the (meth)acrylic compound include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, ( meth) isobutyl acrylate, tert-butyl (meth) acrylate, amyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( Alkyl (meth)acrylates such as n-dodecyl methacrylate and n-octadecyl (meth)acrylate; cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butyl (meth)acrylate Aliphatic cyclic vinyl monomers such as cyclohexyl, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate; phenyl (meth)acrylate, benzyl (meth)acrylate (meth)acrylate dicyclopentenyl acrylate, dicyclopentenyl (meth)acrylate, and the like. These compounds may be used alone or in combination of two or more.
Among these, isobornyl (meth)acrylate can be set to a relatively high Tg, has a high effect of suppressing the lifting and peeling of the pressure-sensitive adhesive sheet, and has good adhesion to olefin-based adherends. , dicyclopentanyl (meth)acrylate, cyclohexyl (meth)acrylate and adamantyl (meth)acrylate are preferred.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, vinyltoluene, β-methylstyrene, ethylstyrene, p-tert-butylstyrene, vinylxylene, and vinylnaphthalene. mentioned. These compounds may be used alone or in combination of two or more.

Examples of the unsaturated carboxylic acid include (meth)acrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamic acid, and monoalkyl esters of unsaturated dicarboxylic acids (maleic acid, monoalkyl esters of fumaric acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, etc.). These compounds may be used alone or in combination of two or more.

Examples of the unsaturated acid anhydride include maleic anhydride, itaconic anhydride, and citraconic anhydride. These compounds may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing unsaturated compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-Hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol, mono(meth)acrylic ester of polyalkylene glycol such as polypropylene glycol, p-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol, o-isopropenylphenol and the like. These compounds may be used alone or in combination of two or more.

Examples of the amino group-containing unsaturated compounds include dimethylaminomethyl (meth)acrylate, diethylaminomethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, (meth) ) 2-(di-n-propylamino)ethyl acrylate, 2-dimethylaminopropyl (meth)acrylate, 2-diethylaminopropyl (meth)acrylate, 2-(di-n-propylamino)acrylate (meth) ) propyl, 3-dimethylaminopropyl (meth)acrylate, 3-diethylaminopropyl (meth)acrylate, 3-(di-n-propylamino)propyl (meth)acrylate and the like. These compounds may be used alone or in combination of two or more.

Examples of the amide group-containing unsaturated compounds include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and N-methylol(meth)acrylamide. These compounds may be used alone or in combination of two or more.

Examples of the alkoxyl group-containing unsaturated compounds include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(n-propoxy)ethyl (meth)acrylate, and 2-(n-propoxy)acrylate (meth)acrylate. -(n-butoxy) ethyl, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 2-(n-propoxy) propyl (meth) acrylate, 2-(meth) acrylate and n-butoxy)propyl. These compounds may be used alone or in combination of two or more.

Examples of the cyano group-containing unsaturated compounds include cyanomethyl (meth)acrylate, 1-cyanoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, and (meth)acrylic acid. 2-cyanopropyl, 3-cyanopropyl (meth) acrylate, 4-cyanobutyl (meth) acrylate, 6-cyanohexyl (meth) acrylate, 2-ethyl-6-cyanohexyl (meth) acrylate, (meth) ) 8-cyanooctyl acrylate and the like. These compounds may be used alone or in combination of two or more.

Examples of the nitrile group-containing unsaturated compounds include (meth)acrylonitrile, ethacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile and the like. These compounds may be used alone or in combination of two or more.

Examples of the maleimide compounds include maleimide, N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N -(4-methylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-benzylmaleimide, N-naphthylmaleimide and the like. These compounds may be used alone or in combination of two or more.

In addition to the above compounds, dialkyl esters of unsaturated dicarboxylic acids, vinyl ester compounds, vinyl ether compounds, and the like can also be used.
Examples of dialkyl esters of unsaturated dicarboxylic acids include dialkyl esters of maleic acid, fumaric acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, and citraconic anhydride.
Examples of the vinyl ester compounds include methylene aliphatic monocarboxylic acid esters, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl butyrate, vinyl benzoate, vinyl formate, and vinyl cinnamate.
Examples of the vinyl ether compound include vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl isobutyl ether, vinyl phenyl ether, vinyl cyclohexyl ether and the like.

As described above, the vinyl polymer (A) in the present invention is a polymer having a narrow molecular weight distribution represented by Mw/Mn, and can be produced by a known production method without particular limitations.
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 more 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.

(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 vinyl polymer (A) in the present invention, a polymerization solvent known in living radical polymerization can be used. 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 in the present invention contains the tackifier and acrylic pressure-sensitive adhesive polymer (B) described above. The acrylic adhesive polymer (B) is described below.
The acrylic adhesive polymer (B) is a polymer containing (meth)acrylic acid alkyl ester as a main structural unit, and preferably has a glass transition temperature (Tg) in the range of -80 to 10°C. If the Tg is in the range of -80°C to 10°C, the pressure-sensitive adhesive composition obtained will have excellent cohesion and good adhesion to curved surfaces.
Furthermore, the acrylic adhesive polymer (B) 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 adhesiveness. More preferably, it is 400,000 or more.

As the monomer constituting the acrylic adhesive polymer (B), a (meth)acrylic having an alkyl group having 4 to 12 carbon atoms can be obtained in that an acrylic copolymer having a low Tg and adhesiveness can be obtained. The use of acid alkyl esters is preferred, for example n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate. , 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, lauryl (meth)acrylate and the like, and preferred monomers Examples include n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, (meth)acrylic acid and isononyl.

The ratio of the (meth)acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms is preferably 30 to 100% by mass, preferably 50 to 99% by mass, based on the total monomers constituting the acrylic copolymer. is more preferred. If the content is less than 30% by mass, the adhesive strength, tackiness, low-temperature adhesiveness, etc. of the obtained adhesive composition will be insufficient.

In addition to (meth)acrylic acid alkyl ester, other monomers copolymerizable therewith can be used for the acrylic adhesive polymer (B) 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; methyl (meth)acrylate, ( (Meth)acrylic acid alkyl esters having an alkyl group of 1 to 3 carbon atoms such as ethyl methacrylate, n-propyl (meth)acrylate, and isopropyl (meth)acrylate; styrene, α-methylstyrene, vinyltoluene vinyl aromatic monomers such as; cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate alicyclic 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-hydroxy hydroxy group-containing monomers such as propyl, 4-hydroxybutyl (meth)acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate and polyethylene-polypropylene glycol mono (meth) acrylate; acrylamide, N-methylolacrylamide, Ethylenically unsaturated carboxylic acid amides and N-substituted compounds such as N-methoxymethylacrylamide and N-methoxybutylacrylamide; Unsaturated alcohols such as allyl alcohol; (meth)acrylonitrile, vinyl acetate, glycidyl (meth)acrylate, dye Acetone acrylamide and the like can be mentioned, and one or more of these can be used.

The production method of the vinyl polymer (B) is not particularly limited, but it can be easily obtained by polymerizing the monomers using a known radical polymerization method such as a solution polymerization method. can. Moreover, it can be produced by the living radical polymerization described in the vinyl polymer (A).
When the solution polymerization method is used, an organic solvent and a vinyl monomer are charged in a reactor, a thermal polymerization initiator such as an organic peroxide or an azo compound is added, and the mixture is heated to 50 to 300° C. for copolymerization. It is possible to obtain the desired vinyl polymer (A). The vinyl polymer may be used as a solution dissolved in an organic solvent, or may be used after distilling off the solvent by heating under reduced pressure.
The method of charging each raw material containing a monomer may be a batch-type initial batch charging in which all raw materials are charged at once, or a semi-continuous charging in which at least one raw material is continuously fed into a reactor. A continuous polymerization system may be employed in which raw materials are continuously supplied and at the same time the produced resin is continuously withdrawn from the reactor.

As the organic solvent used in the solution polymerization method, organic hydrocarbon compounds are suitable, and cyclic ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbon compounds such as benzene, toluene and xylene; Examples include esters, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and alcohols such as methyl orthoformate, methyl orthoacetate, methanol, ethanol, and isopropanol, and one or more of these can be used. Among these polymerization solvents, preferred are ethyl acetate, butyl acetate, acetone and methyl ethyl ketone, which dissolve vinyl polymers well and have relatively low boiling points for easy purification.

An azo compound, an organic peroxide, an inorganic peroxide, or the like can be used as the initiator used in the reaction, but the initiator is not particularly limited. Moreover, a chain transfer agent can also be used together.

Examples of the azo compounds include 2,2′-azobis(isobutyronitrile), 1,1-azobis(cyclohexane-1-carbonitrile), azocumene, 2,2′-azobis(2-methylbutyronitrile). , 2,2′-azobisdimethylvaleronitrile, 4,4′-azobis(4-cyanovaleric acid), 2-(tert-butylazo)-2-cyanopropane, 2,2′-azobis(2,4, 4-trimethylpentane), 2,2'-azobis(2-methylpropane), dimethyl 2,2'-azobis(2-methylpropionate) and the like.

Examples of the organic peroxide include cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydro Peroxide, 1,3-bis(tert-butylperoxy)-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, diisopropylbenzene peroxide, tert-butyl Cumyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, bis(tert-butylcyclohexyl) peroxydicarbonate, tert-butyl peroxybenzoate, 2,5-dimethyl -2,5-di(benzoylperoxy)hexane and the like.

Examples of the inorganic peroxide include potassium persulfate, sodium persulfate and ammonium persulfate.
In addition, as a redox polymerization initiator, sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, ferrous sulfate, etc. are used as reducing agents, and potassium peroxodisulfate, hydrogen peroxide, tert-butyl hydroperoxide. etc. can be used as an oxidizing agent.

The pressure-sensitive adhesive composition in the present invention is not particularly limited in the mixing method as long as it contains the tackifier containing the vinyl polymer (A) and the acrylic pressure-sensitive adhesive polymer (B). A method of mixing a tackifier and an acrylic adhesive polymer (B) may be used, or a product produced by polymerizing an acrylic adhesive polymer (B) in the presence of a tackifier may be used. .
The content of the tackifier in the pressure-sensitive adhesive composition is preferably 0.5 to 60 parts by mass, more preferably 1 part by mass, based on 100 parts by mass of the acrylic adhesive polymer (B). It is up to 40 parts by mass, more preferably 1 to 30 parts by mass.
When the amount of the tackifier used is 0.5 parts by mass or more, the adhesive strength to various adherends tends to be sufficiently improved, and when it is 60 parts by mass or less, good adhesive strength can be obtained. can.

The adhesive composition of the present invention preferably has a glass transition temperature (Tg) in the range of -80 to 10°C, more preferably in the range of -60 to 0°C.
If the Tg is in the range of -80 to 10°C, the adhesion strength to various adherends under high pressure and high temperature conditions is excellent.
Further, in the adhesive layer obtained by applying the adhesive composition to a separator and then drying it, the glass transition temperature (Tg) of the entire adhesive layer is -80 to 10 ° C., and the X The glass transition temperature (Tg) calculated from the surface layer portion obtained by line photoelectron spectroscopy is 40 ° C. or higher, and the glass transition temperature (Tg) of the surface layer portion is equal to the glass transition temperature (Tg ) by at least 30°C.
Under these conditions, the pressure-sensitive adhesive has excellent adhesive strength to various adherends under high pressure and high temperature conditions.

In addition to the tackifier and the acrylic adhesive polymer (B), the pressure-sensitive adhesive composition in the present invention may optionally include a cross-linking agent (curing agent), other tackifier, a plasticizer, and an antioxidant. , an ultraviolet absorber, an anti-aging agent, a flame retardant, an antifungal agent, a silane coupling agent, a filler, a coloring agent, and other additives.

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, preferably, a compound having two or more isocyanate groups is used, and various aromatic, aliphatic, and alicyclic isocyanate compounds, and modified products of these isocyanate compounds (prepolymers, etc.) ) 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).
Examples of the aliphatic isocyanate 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 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 adhesive polymer (B). , more preferably 0.03 to 5 parts by mass, still more preferably 0.05 to 2 parts by mass.

Other tackifiers 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, (Hydrogenated) petroleum resins; coumarone-indene resins; hydrogenated aromatic copolymers; styrene resins; phenolic resins;

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)-9,10-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 phyto, cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl)phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)octylphosphite, etc. Phosphorus-based antioxidants and the like are included.

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, Examples thereof include nickel-based UV stabilizers such as nickel complex-3,5-di-tert-butyl-4-hydroxybenzyl-phosphate monoethylate and nickel-dibutyldithiocarbamate.

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 in the present invention is not particularly limited as long as it contains the tackifier and the acrylic pressure-sensitive adhesive polymer (B).
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 above solution-type pressure-sensitive adhesive composition and 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.

In addition, the pressure-sensitive adhesive composition in the present invention is a composition containing a monofunctional and/or polyfunctional (meth)acrylic acid-based monomer, a photopolymerization initiator, etc., so that it is active against ultraviolet rays and the like. It may be used in the form of a photocurable pressure-sensitive adhesive composition that is cured by energy rays.
The tackifier in the present invention does not inhibit curing during UV curing, unlike general tackifying resins such as rosin-based resins and terpene-based resins. Therefore, when used in a photocurable pressure-sensitive adhesive composition such as UV-curing, it is possible to improve adhesive properties such as adhesive strength without adversely affecting curability.

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. These compounds may be used alone or in combination of two or more.

The content of the tackifier in the photocurable pressure-sensitive adhesive composition is preferably 0.00 per 100 parts by mass of the acrylic pressure-sensitive adhesive polymer and the monofunctional and/or polyfunctional (meth)acrylic monomer. It is 5 to 60 parts by mass, more preferably 1 to 40 parts by mass, still more preferably 1 to 30 parts by mass.

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 may 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.

Moreover, when used as a photo-curing adhesive, it can be suitably used as an adhesive for producing laminates constituting optical discs and various optical displays.

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. It may be transferred to the substrate after being processed and dried.
The thickness of the adhesive formed on the 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 insulating tapes, laminates, and the like.

The pressure-sensitive adhesive composition containing the tackifier in the present invention is excellent in transparency and has high adhesive strength to various adherends such as glass, so that it can be used for touch panels, liquid crystal display devices, organic EL display devices, It is also suitable for laminating displays such as 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: Polymer A-1)
A 1 L flask equipped with a stirrer and a thermometer was charged with 7.69 g of 2-cyano-propyldodecyltrithiocarbonate, 0.856 g of 2,2'-azobis-2-methylbutyronitrile, 160 g of methyl methacrylate, and 40 g of isobornyl methacrylate. 125.6 g of butyl acetate was charged, sufficiently degassed by nitrogen bubbling, and polymerization was initiated in a constant temperature bath at 60°C. After 6 hours, it was cooled to room temperature, purified by reprecipitation with methanol, and vacuum-dried overnight at 80°C. 10 g of the obtained solid was dissolved in 50 g of tetrahydrofuran, charged into a 200 mL flask, 1.86 g of cyclohexyl acrylate and 2.13 g of propylamine were added, and reacted at 40° C. for 24 hours. The resulting solution was purified by reprecipitation with methanol and vacuum dried overnight at 80°C. The molecular weight of the obtained vinyl copolymer was 8500 in Mn and 1.16 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 2: Polymer A-2)
A 1 L flask equipped with a stirrer and a thermometer was charged with 7.69 g of 2-cyano-propyldodecyltrithiocarbonate, 1.284 g of 2,2'-azobis-2-methylbutyronitrile, 160 g of methyl methacrylate, 40 g of isobornyl methacrylate, 200 g of butyl acetate was charged, sufficiently degassed by nitrogen bubbling, and polymerization was initiated in a constant temperature bath at 60°C. After 6 hours, the mixture was cooled to room temperature, purified by reprecipitation with a mixed solvent of methanol and water in a ratio of 9:1, and vacuum-dried at 80° C. overnight. 10 g of the obtained solid was dissolved in 50 g of tetrahydrofuran, charged into a 200 mL flask, 1.86 g of cyclohexyl acrylate and 2.13 g of propylamine were added, and reacted at 40° C. for 24 hours. The resulting solution was purified by reprecipitation with methanol and vacuum dried overnight at 80°C. The molecular weight of the obtained vinyl copolymer was 8220 in Mn and 1.24 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 3: Polymer A-3)
A mixture of 263 parts by mass of butyl acetate and 1.1 parts by mass of dimethyl 2,2′-azobis(2-methylpropionate) was charged into a 1 L flask equipped with a stirrer and a thermometer, and the mixture was passed through nitrogen gas. The mixture was sufficiently degassed by bubbling, and the internal temperature of the mixture was raised to 90°C. Separately, a mixture of 202 parts by mass of methyl methacrylate, 50 parts by mass of isobornyl methacrylate, 17 parts by mass of dimethyl 2,2'-azobis(2-methylpropionate), and 90 parts by mass of butyl acetate was added from the dropping funnel into the flask. Polymerization was carried out by adding dropwise to the solution over 5 hours. After completion of the dropwise addition, the polymerization solution was purified by reprecipitation with a mixed solvent having a ratio of methanol to water of 8:2, and vacuum-dried at 80° C. overnight. The molecular weight of the obtained vinyl copolymer was 6050 in Mn and 1.54 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 4: Polymer A-4)
A mixture of 263 parts by mass of butyl acetate and 1.1 parts by mass of dimethyl 2,2′-azobis(2-methylpropionate) was charged into a 1 L flask equipped with a stirrer and a thermometer, and the mixture was passed through nitrogen gas. The mixture was sufficiently degassed by bubbling, and the internal temperature of the mixture was raised to 90°C. Separately, a mixture of 202 parts by mass of methyl methacrylate, 50 parts by mass of isobornyl methacrylate, 17 parts by mass of dimethyl 2,2'-azobis(2-methylpropionate), and 90 parts by mass of butyl acetate was added from the dropping funnel into the flask. Polymerization was carried out by adding dropwise to the solution over 5 hours. After completion of dropping, the polymerization solution was purified by reprecipitation with methanol, and vacuum-dried overnight at 80°C. The molecular weight of the obtained vinyl copolymer was 7100 for Mn and 1.38 for Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 5: Polymer B-1)
A 3 L flask equipped with a stirrer and a thermometer was charged with 468 parts by mass of methoxyethyl acrylate, 30 parts by mass of 2-hydroxyethyl acrylate, 102 parts by mass of butyl acrylate, and 890 parts by mass of ethyl acetate. The internal temperature of the mixture was raised to 75° C., 0.11 parts by mass of 2,2′-azobis(2,4-dimethylvaleronitrile) was added, and polymerization was performed for 5 hours. Ethyl acetate was added so that the solid content concentration was 30% to obtain an ethyl acetate solution of polymer B-1. The molecular weight of the obtained polymer was 125,600 in Mn and 6.5 in Mw/Mn from GPC (gel permeation chromatography) measurement (converted to polystyrene).

(Synthesis Example 6: Polymer B-2)
288 parts by mass of methoxyethyl acrylate, 30 parts by mass of 2-hydroxyethyl acrylate, 102 parts by mass of butyl acrylate, 180 parts by mass of methyl acrylate, and 890 parts by mass of ethyl acetate were charged into a 3 L flask equipped with a stirrer and a thermometer. , This mixed solution is sufficiently degassed by bubbling nitrogen gas, the internal temperature of the mixed solution is raised to 75°C, and 0.10 part by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) is charged. , polymerized for 5 hours. Ethyl acetate was added so that the solid content concentration was 30% to obtain an ethyl acetate solution of polymer B-1. As for the molecular weight of the obtained polymer, Mn was 112000 and Mw/Mn was 7.2 by GPC (gel permeation chromatography) measurement (converted to polystyrene).

For the polymer 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 weight average molecular weight (Mw)/number average molecular weight (Mn) We calculated the ratio of The results are shown in Tables 1 and 2.

(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 SuperMultiporeHZ-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 250° 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 250°C at min.
Measuring instrument: DSC6220 manufactured by SII Nano Technology Co., Ltd.
Measurement atmosphere: Nitrogen atmosphere

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Example 1
A polymer (A-1) solution having a solid content concentration of 30% by mass obtained by dissolving the polymer A-1 (2 parts by mass) obtained in Synthesis Example 1 above in ethyl acetate was obtained in Synthesis Example 3 above. By mixing with the polymer B-1 solution, a solution containing polymer A-1 (2 parts by mass) and polymer B-1 (100 parts by mass) and having a solid content of 30% by mass was prepared. Here, Takenate D-110N (an isocyanate-based cross-linking agent manufactured by Mitsui Chemicals, Inc., solid content concentration 75% by mass) (0.08 parts by mass) was mixed as a cross-linking agent to obtain a pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition was applied onto a polyethylene terephthalate (PET) separator having a thickness of 38 μm so that the thickness after drying was 25±2.0 μm. By drying the pressure-sensitive adhesive composition at 80° C. for 4 minutes, ethyl acetate is removed and a cross-linking reaction is allowed to occur, and a PET separator with a thickness of 38 μm having a different peeling force from the above separator is attached. Then, it was aged at 40° C. for 5 days to obtain an adhesive film sample with a separator on both sides. Various measurements and evaluations were performed on the obtained adhesive film samples by the following methods, and the results are shown in Table 3.

<Gel fraction for acrylic adhesive polymer (B)>
0.2 g of the adhesive was sampled from the adhesive film sample, and the initial weight of the adhesive was weighed. The adhesive was immersed in 50 g of ethyl acetate and allowed to stand at room temperature for 16 hours. Then, it was filtered through a 200-mesh wire mesh, and the residue remaining on the mesh was dried at 80° C. for 3 hours and weighed. From the initial weight and the weight of the residue, the gel fraction relative to the acrylic adhesive polymer (B) was calculated according to the following formula.
Gel fraction (%) = (weight of residue) / [(initial weight) x (solid content of acrylic adhesive polymer (B)) / (solid content of entire adhesive composition)] x 100

<Transparency (haze value)>
The release film was peeled off from the adhesive film sample, transferred to a glass plate (1 mm thick), and the other release film was peeled off. After standing for one day under conditions of 23° C. and 50% RH, transparency was evaluated by measuring the haze value using a haze meter “Haze Meter NDH2000” (model name) manufactured by Nippon Denshoku Co., Ltd.

<Tg of the surface layer portion of the pressure-sensitive adhesive layer>
From the peak area ratio of O1s and C1s by X-ray photoelectron spectroscopy (XPS) measurement of the adhesive film sample, the vinyl Each mass fraction (w _A and w B ) of the polymer (A) and the acrylic adhesive polymer ( _B ) was calculated, and the Tg of the surface layer portion was calculated based on the FOX formula.
In addition, the XPS measurement was measured on condition of the following.
Apparatus: PHI5000 VersaProbe manufactured by ULVAC-Phi
X-ray: Al-Kα (1486.6 eV)
X-ray incident angle to the sample: 0° (angle with respect to the normal to the sample measurement surface)
Photoelectron detection angle: 45° (angle with respect to the normal to the sample measurement surface)

<Peel strength against PMMA and polycarbonate (PC) plate>
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. Polymethyl methacrylate plate (manufactured by Mitsubishi Chemical Co., Ltd., Acrylite L001) and polycarbonate plate (manufactured by Mitsubishi Gas Chemical Co., Ltd., Iupilon NF-2000) are used as adherends, and the adhesive sheet for the above evaluation is attached, and tabletop pressure defoaming is performed. After crimping for 20 minutes under conditions of 0.5 MPa and 50 ° C. using a device TBR-200 (manufactured by Chiyoda Electric Industry Co., Ltd.), using a tensile tester Strograph R type with a constant temperature bath (manufactured by Toyo Seiki Co., Ltd.) , a temperature of 85° C., and a peeling speed of 300 mm/min. Under the conditions of , the 180 degree peel strength of the adhesive sheet was measured according to JIS Z-0237 "Adhesive tape/adhesive sheet test method" and was taken as adhesive strength.

Examples 2 to 4
In the same manner as in Example 1, except that polymer A-1 or A-2 and polymer B-1 or B-2 were used in the proportions shown in Table 3, a pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive film sample got The obtained adhesive film samples were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Comparative Examples 1 to 4
In the same manner as in Example 1, except that polymer A-3 or A-4 and polymer B-1 or B-2 were used in the proportions shown in Table 4, a pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive film sample got The obtained adhesive film samples were evaluated in the same manner as in Example 1, and the results are shown in Table 4.

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06

06

As shown in Tables 3 and 4, vinyl polymer A-1 (Mw/Mn is 1.16) or vinyl polymer A-2 (Mw/Mn is 1.24) was used as a tackifier. The adhesive film samples of Examples 1 to 4 were obtained from Comparative Examples 2 to 2 using vinyl polymer A-3 (Mw/Mn is 1.54) or A-4 (Mw/Mn is 1.38) as the adhesive imparting agent. 4, the adhesion to PMMA and PC, especially at a high temperature of 85° C., is superior.

Claims (5)

A glass transition temperature (Tg) of 80 to 200° C., a number average molecular weight of 3,000 to 20,000, and a weight average molecular weight (Mw)/number average molecular weight (Mn) ratio of 1.05 to 1.30 comprising a vinyl polymer (A),
The monomer constituting the vinyl polymer (A) contains at least one of isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, cyclohexyl (meth)acrylate and adamantyl (meth)acrylate. tackifier containing . The method for producing a tackifier according to claim 1, wherein the vinyl polymer (A) is a polymer produced by living radical polymerization. A pressure-sensitive adhesive composition comprising the tackifier according to claim 1 and an acrylic pressure-sensitive adhesive polymer (B). The pressure-sensitive adhesive composition according to claim 3, wherein the pressure-sensitive adhesive composition has a glass transition temperature (Tg) of -80 to 10°C. In the adhesive layer obtained by applying the adhesive composition to a separator and then drying it, the glass transition temperature (Tg) of the entire adhesive layer is -80 to 10 ° C., and the adhesive layer X The glass transition temperature (Tg) calculated from the surface layer portion obtained by line photoelectron spectroscopy is 40 ° C. or higher, and the glass transition temperature (Tg) of the surface layer portion is the glass transition temperature of the entire adhesive layer ( 5. The pressure-sensitive adhesive composition according to claim 3 or 4, which is 30° C. or more higher than Tg).