WO2019188357A1 - Adhesive composition, adhesive sheet and method for producing ethylenically unsaturated group-containing acrylic resin - Google Patents

Abstract

The present invention provides, as an active energy ray-curable, releasable adhesive composition which enables the achievement of an adhesive that exhibits excellent heat resistance and good adhesiveness before active energy ray irradiation, while having excellent releasability (contamination resistance and low adhesiveness) after active energy ray irradiation even after being heated, an adhesive composition which contains an ethylenically unsaturated group-containing acrylic resin that contains an ethylenically unsaturated group-containing structural moiety represented by general formula (1) in a side chain of the acrylic resin, while having an ethylenically unsaturated group content of 25-500 mmol relative to the amount of the ethylenically unsaturated group-containing acrylic resin. (In the formula, R1 represents a substituent which contains an ethylenically unsaturated group; R2 represents an organic group that contains at least one element selected from among C, O, N and S (excluding a carbamate group); and X represents O or NH.)

Description

Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet and method for producing ethylenically unsaturated group-containing acrylic resin

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition containing a specific ethylenically unsaturated group-containing acrylic resin, a pressure-sensitive adhesive sheet, and a method for producing an ethylenically unsaturated group-containing acrylic resin. The present invention relates to a pressure-sensitive adhesive composition useful for a semiconductor fixing pressure-sensitive adhesive sheet such as a temporary surface protection such as a semiconductor wafer dicing process.

Active energy ray-curable resin compositions that are cured by irradiating active energy rays such as ultraviolet rays and electron beams are known, and are used for applications such as adhesives, adhesives, paints, inks, coating materials, and optical modeling materials. It is used. In addition, the active energy ray-curable resin composition is a surface protection for temporarily protecting the surface for the purpose of preventing dirt and damage of a workpiece in a processing step such as cutting or drilling an electronic component. In recent years, the pressure-sensitive adhesive sheet for protecting the surface is used not only for electronic parts but also for processing various members.

The pressure-sensitive adhesive sheet is required to have a suitable pressure-sensitive adhesive force on the workpiece for reasons such as the recent miniaturization of processing and the thinning of the workpiece. It is necessary to peel off the sheet, and it is required that the sheet can be peeled off with a light force without any adhesive residue.

The active energy ray-curable resin composition used for the pressure-sensitive adhesive sheet includes, for example, blending at least one of a monomer and an oligomer having an ethylenically unsaturated group with an acrylic resin, or an ethylenically unsaturated group with the acrylic resin itself. Active energy ray curability is expressed by containing. Among them, the use of an ethylenically unsaturated group-containing acrylic resin containing an ethylenically unsaturated group in the acrylic resin itself is because the acrylic resin itself forms a crosslinked structure by irradiation with active energy rays. This is advantageous in that the elastic modulus of the resin is easily increased and the uncrosslinked component hardly remains on the adherend.

As an ethylenically unsaturated group-containing acrylic resin used for such a temporary surface protecting pressure-sensitive adhesive sheet, for example, Patent Document 1 discloses that an acrylic polymer copolymerized with 2-hydroxyethyl acrylate is 2 -Acrylic resins containing ethylenically unsaturated groups by urethanation of methacryloyloxyethyl isocyanate are described.

Further, in Patent Document 2, electronic component processing using an acrylic resin containing an ethylenically unsaturated group by esterifying 2-hydroxyethyl methacrylate with an acrylic copolymer copolymerized with methacrylic acid. An adhesive tape is described.

Also, in recent electronic component manufacturing processes, components with adhesive sheets attached are often exposed to high temperatures, and therefore, adhesive sheets used in electronic component manufacturing processes are resistant to high temperatures. Sex is also required.

JP 2010-53346 A JP 2016-121231 A

However, in the disclosed technique of Patent Document 1, the releasability by irradiation with active energy rays at normal temperature is good, but when exposed to high energy conditions of 150 ° C. or higher and then subjected to active energy ray irradiation to peel off, Since the urethane bond, which is the bonding part of the ethylenically unsaturated group in the acrylic resin, is easily decomposed by heat during the high-temperature process, the adhesive force is not easily lowered even when irradiated with active energy rays, and the adherend is peeled off at the time of peeling. Easy to leave glue. Therefore, further improvement in heat resistance is demanded.

Moreover, in the disclosed technology of Patent Document 2, although an ethylenically unsaturated group is introduced through an ester bond, the main chain portion into which the unsaturated group is introduced is a structure derived from methacrylic acid, so that it depends on heat. The main chain decomposition reaction is likely to occur and the heat resistance is still inferior, and further improvement is required.

Therefore, in the present invention, under such a background, the adhesive strength before irradiation with active energy rays is good, the heat resistance is excellent, and the peelability after irradiation with active energy rays (contamination resistance, fine Provided is an active energy ray-curable peelable pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive having excellent adhesiveness.

However, by using an acrylic resin containing a specific amount of an ethylenically unsaturated group having a specific structure, the present inventors have good adhesive strength before irradiation with active energy rays and excellent heat resistance. The present inventors have found a pressure-sensitive adhesive composition that can be used as a pressure-sensitive adhesive and can provide a pressure-sensitive adhesive having excellent peelability (contamination resistance and slight adhesion) after irradiation with active energy rays.

In addition, the present inventors react the hydroxyl group-containing acrylic resin (α) with the ethylenically unsaturated group-containing carboxylic acid (β) in the presence of the compound (I) represented by the general formula (2). Thus, it has been found that an ethylenically unsaturated group can be added to an acrylic resin in a high yield even at a low temperature without having a urethane bond.

That is, the present invention contains an ethylenically unsaturated group-containing structure represented by the following general formula (1) in the side chain of the acrylic resin, and the ethylenically unsaturated group content is ethylenically unsaturated. A first aspect is a pressure-sensitive adhesive composition containing an ethylenically unsaturated group-containing acrylic resin in an amount of 25 to 500 mmol / 100 g based on the group-containing acrylic resin.

The second gist of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition of the first gist is crosslinked.

And this invention is ethylenic which makes a hydroxyl-containing acrylic resin ((alpha)) and ethylenically unsaturated group containing carboxylic acid ((beta)) react in presence of the compound (I) represented by following General formula (2). A method for producing an unsaturated group-containing acrylic resin is a third aspect.

The pressure-sensitive adhesive composition of the present invention contains an ethylenically unsaturated group-containing structural site represented by the following general formula (1) in the side chain of the acrylic resin, and the content of the ethylenically unsaturated group is ethylene. It contains an ethylenically unsaturated group-containing acrylic resin in an amount of 25 to 500 mmol / 100 g based on the polymerizable unsaturated group-containing acrylic resin. Therefore, the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition contains an acrylic resin containing a predetermined amount of a specific ethylenically unsaturated group-containing structural site in the side chain. It has excellent adhesive strength and peelability after irradiation with active energy rays. Moreover, since the said ethylenically unsaturated group containing structure site | part does not have a carbamate group, the said adhesive composition and adhesive sheet are excellent in heat resistance, even after heating at high temperature, after irradiation of an active energy ray. Excellent peelability.

In the present invention, in particular, when the ethylenically unsaturated group-containing acrylic resin contains a hydroxyl group, the adhesive strength before irradiation with active energy rays is further improved.

Further, when the pressure-sensitive adhesive composition of the present invention contains a cross-linking agent, the pressure-sensitive adhesive force before irradiation with active energy rays is further improved.

Furthermore, when the pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator, the curability of the ethylenically unsaturated group-containing acrylic resin is further improved by irradiation with active energy rays, and the peeling after irradiation with active energy rays is further performed. It will be excellent.

In the present invention, in particular, the ethylenically unsaturated group-containing acrylic resin comprises a hydroxyl group-containing acrylic resin (α) and an ethylenically unsaturated group-containing carboxylic acid (β). When the reaction is carried out in the presence of the compound (I) represented by the formula, an ethylenically unsaturated group-containing acrylic resin can be obtained in a high yield. Therefore, the adhesive strength before irradiation with active energy rays and the releasability after irradiation with active energy rays are superior, and the heat resistance is excellent, and even after heating at high temperatures, the releasability after irradiation with active energy rays is excellent. It will be a thing.

And especially in this invention, the said ethylenically unsaturated group containing acrylic resin is an esterification reaction of a hydroxyl-containing acrylic resin ((alpha)) and (meth) acrylic anhydride ((gamma)). If it exists, an ethylenically unsaturated group containing acrylic resin can be obtained with a high yield. Therefore, the adhesive strength before irradiation with active energy rays and the releasability after irradiation with active energy rays are superior, and the heat resistance is excellent, and even after heating at high temperatures, the releasability after irradiation with active energy rays is excellent. It will be a thing.

In addition, according to the production method of the present invention, the hydroxyl group-containing acrylic resin (α) and the ethylenically unsaturated group-containing carboxylic acid (β) are present in the presence of the compound (I) represented by the general formula (2). Because of the reaction, an ethylenically unsaturated group-containing acrylic resin can be obtained in high yield. Moreover, this manufacturing method can obtain the ethylenically unsaturated group containing acrylic resin suitable also for the use exposed to high temperature, without carrying out the complicated operation for removing a by-product after reaction.

Among the production methods of the present invention, in particular, the hydroxyl group-containing acrylic resin (α) and the ethylenically unsaturated group-containing carboxylic acid (β) are represented by the compound (I) represented by the general formula (2). When the reaction is carried out in the presence of, further, when the reaction is carried out in the presence of one or more magnesium compounds and one or more alkali metal compounds, an ethylenically unsaturated group-containing acrylic resin can be obtained in a higher yield. it can.

Furthermore, among the production methods of the present invention, in particular, when the alkali metal constituting the alkali metal compound is lithium, an ethylenically unsaturated group-containing acrylic resin can be obtained in a higher yield.

Among the production methods of the present invention, particularly when the compound (I) represented by the general formula (2) is di-t-butyl dicarbonate, it contains an ethylenically unsaturated group in a higher yield. An acrylic resin can be obtained.

Further, among the production methods of the present invention, in particular, the magnesium compound 0.001 to 1000 mol% and the alkali metal compound 0.001 to 1000 mol% with respect to the ethylenically unsaturated group-containing carboxylic acid (β). When the reaction is carried out in the presence, an ethylenically unsaturated group-containing acrylic resin can be obtained in a higher yield.

Furthermore, among the production methods of the present invention, in particular, the content of the hydroxyl group-containing monomer (a1) constituting the hydroxyl group-containing acrylic resin (α) is 0.1 to 50% by mass with respect to the entire polymerization component. When it exists, when using the obtained ethylenically unsaturated group containing acrylic resin as an adhesive, it can harden | cure by irradiating an active energy ray and can have more favorable peelability.

Among the production methods of the present invention, in particular, the ethylenically unsaturated group content of the ethylenically unsaturated group-containing acrylic resin is 25 to 500 mmol / 100 g based on the ethylenically unsaturated group-containing acrylic resin. When the obtained ethylenically unsaturated group-containing acrylic resin is used as a pressure-sensitive adhesive, it can be cured by irradiating with active energy rays to have better releasability.

Among the production methods of the present invention, in particular, when the hydroxyl group-containing acrylic resin (α) has an acid value of 10 mgKOH / g or less, it is more efficient at higher yield without gelation during the reaction. In addition, an ethylenically unsaturated group-containing acrylic resin can be obtained.

Hereinafter, although the form for implementing this invention is demonstrated concretely, this invention is not limited to these.
In the present invention, “(meth) acryl” means acryl or methacryl, “(meth) acryloyl” means acryloyl or methacryloyl, and “(meth) acrylate” means acrylate or methacrylate.
The “acrylic resin” is a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate monomer.
In the present invention, the “sheet” is not particularly distinguished from “film” or “tape”, but is described as meaning including these.

The pressure-sensitive adhesive composition of the present invention is usually mainly used for a pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet on the premise that the pressure-sensitive adhesive composition is peeled after being bonded to a workpiece such as a metal plate, a plastic plate, or a semiconductor wafer. The pressure-sensitive adhesive sheet is formed by applying a pressure-sensitive adhesive composition onto a base material sheet to form a pressure-sensitive adhesive layer, and is bonded by irradiating an active energy ray after being bonded to a workpiece. The agent layer is cured and the adhesive force is lowered, and can be easily peeled off from the workpiece.

The pressure-sensitive adhesive composition of the present invention contains an acrylic resin containing a predetermined amount of an ethylenically unsaturated group-containing structural moiety represented by the following general formula (1).

The acrylic resin containing the ethylenically unsaturated group-containing structural moiety represented by the general formula (1) is obtained by combining a hydroxyl group-containing acrylic resin (α) and an ethylenically unsaturated group-containing carboxylic acid (β) with a compound (I ) Or in the presence of a hydroxyl group-containing acrylic resin (α) and (meth) acrylic anhydride (γ). These components will be described below.

[Hydroxyl-containing acrylic resin (α)]
The hydroxyl group-containing acrylic resin (α) is a hydroxyl group-containing monomer (a1), an alkyl (meth) acrylate (a2), preferably a functional group-containing monomer (a3) (excluding the hydroxyl group-containing monomer (a1)), Furthermore, it is obtained by polymerizing other copolymerizable monomers (a4) as necessary.

The hydroxyl group of the hydroxyl group-containing monomer (a1) reacts with the ethylenically unsaturated group-containing carboxylic acid (β) or (meth) acrylic anhydride (γ) in the hydroxyl group-containing acrylic resin (α) after polymerization. It will be a point.
Further, the hydroxyl group also serves as a reaction point with a crosslinking agent described later, and is more than the amount consumed in the reaction with the ethylenically unsaturated group-containing carboxylic acid (β) or (meth) acrylic anhydride (γ). It is preferable to contain.

The hydroxyl group-containing monomer (a1) is one that excludes methacrylate monomers from the viewpoint of heat resistance, and examples thereof include hydroxyl group-containing acrylate monomers and hydroxyl group-containing acrylamide monomers. Specific examples of the hydroxyl group-containing acrylate monomer or the hydroxyl group-containing acrylamide monomer include 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate, 6-hydroxyhexyl acrylate, 8-hydroxy. Hydroxyalkyl esters such as octyl acrylate, hydroxyalkyl acrylamides such as 2-hydroxyethyl acrylamide, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl acrylate, oxyalkylene-modified monomers such as diethylene glycol acrylate and polyethylene glycol acrylate, 2-acrylic Primary hydroxyl group-containing monomer such as leuoxyethyl-2-hydroxyethylphthalic acid; 2 Secondary hydroxyl group-containing monomers such as hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-chloro-2-hydroxypropyl acrylate; tertiary hydroxyl group-containing monomers such as 2,2-dimethyl 2-hydroxyethyl acrylate . These can be used alone or in combination of two or more.
Among the hydroxyl group-containing monomers (a1), the primary hydroxyl group-containing monomer is excellent in reactivity with an ethylenically unsaturated group-containing carboxylic acid (β) or (meth) acrylic anhydride (γ) described later. Particularly preferred are 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate.

The content of the hydroxyl group-containing monomer (a1) is usually 0.1 to 50% by weight, preferably 5 to 40% by weight, more preferably based on the entire polymerization component of the hydroxyl group-containing acrylic resin (α). 10 to 35% by weight. If the content is too large, crosslinking proceeds before the drying step, which tends to cause problems in coating properties. If the content is too small, a sufficient amount of ethylenically unsaturated group-containing carboxylic acid (β) or ( It cannot react with (meth) acrylic anhydride (γ), and the peelability after irradiation with active energy rays tends to decrease.

The alkyl (meth) acrylate (a2) is a main component of a polymerization component for obtaining a hydroxyl group-containing acrylic resin (α). In the alkyl (meth) acrylate (a2), the alkyl group usually has 1 to 24 carbon atoms, preferably 1 to 20, particularly preferably 1 to 12, and more preferably 1 to 8. If the number of carbon atoms is too large, the polymerizability becomes low, and therefore, it tends to remain as an unreacted monomer in the hydroxyl group-containing acrylic resin (α), and there is a tendency that contamination to the workpiece and adhesive residue are likely to occur.

Specific examples of the alkyl (meth) acrylate (a2) include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and tert-butyl (meth). Acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, Aliphatic (meth) acrylic acid alkyl esters such as cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate; cyclohexyl (meth) acrylate, isobornyl (meth) acrylate (Meth) acrylic acid alkyl ester of the alicyclic and the like of. These may be used alone or in combination of two or more.
Among the above alkyl (meth) acrylates (a2), methyl (meth) acrylate, n-butyl (meth) acrylate, 2-, are preferable in terms of copolymerizability, adhesive properties, ease of handling, and availability of raw materials. Ethylhexyl (meth) acrylate is preferred.

The content of the alkyl (meth) acrylate (a2) is usually 30 to 99% by weight, preferably 40 to 95% by weight, particularly with respect to the total polymerization components of the hydroxyl group-containing acrylic resin (α). Preferably, it is 50 to 90% by weight. When the content is too small, the adhesive strength before irradiation with active energy rays tends to decrease, and when the content is too large, the adhesive strength before irradiation with active energy rays tends to be too high.

In the present invention, it is preferable that the acrylic resin contains a hydroxyl group from the viewpoint of excellent reaction with the crosslinking agent described later, but in addition to the hydroxyl group-containing monomer (a1), a functional group-containing monomer that reacts with the crosslinking agent described later. It is also preferable to contain (a3) as a polymerization component.

Examples of the functional group-containing monomer (a3) include carboxy group-containing monomers, amino group-containing monomers, amide group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, and acetoacetyl group-containing monomers. . These functional group-containing monomers can be used alone or in combination of two or more.

Examples of the carboxy group-containing monomer include (meth) acrylic acid, (meth) acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, and acrylamide N-glycolic acid. And cinnamic acid. Of these, (meth) acrylic acid is preferably used from the viewpoint of copolymerization.

The content of the carboxy group-containing monomer is usually 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.3% by weight, based on the entire polymerization component of the hydroxyl group-containing acrylic resin (α). % Or less. If the content is too large, the member to be processed tends to be deteriorated, and the crosslinking proceeds before the drying step, which tends to cause problems in coating properties.

Examples of the amino group-containing monomer include N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate.

The content of the amino group-containing monomer is usually 10% by weight or less, preferably 5% by weight or less, more preferably 2% by weight or less based on the entire polymerization component of the hydroxyl group-containing acrylic resin (α). . When there is too much this content, bridge | crosslinking will advance before a drying process and there exists a tendency for a problem to arise in coating property.

Examples of the amide group-containing monomer include ethoxymethyl (meth) acrylamide, n-butoxymethyl (meth) acrylamide, (meth) acryloylmorpholine, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, dimethylaminopropyl acrylamide, ( And (meth) acrylamide monomers such as (meth) acrylamide and N-methylol (meth) acrylamide.

The content of the amide group-containing monomer is usually 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less, based on the entire polymerization component of the hydroxyl group-containing acrylic resin (α). . When there is too much this content, bridge | crosslinking will advance before a drying process and there exists a tendency for a problem to arise in coating property.

Examples of the glycidyl group-containing monomer include glycidyl methacrylate and allyl glycidyl methacrylate.

The content of the glycidyl group-containing monomer is usually 20% by weight or less, preferably 15% by weight or less, more preferably 10% by weight or less, based on the entire polymerization component of the hydroxyl group-containing acrylic resin (α). . When there is too much this content, bridge | crosslinking will advance before a drying process and there exists a tendency for a problem to arise in coating property.

Examples of the sulfonic acid group-containing monomer include olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, 2-acrylamido-2-methylolpropane sulfonic acid, styrene sulfonic acid, and salts thereof. .

The content of the sulfonic acid group-containing monomer is usually 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.3%, based on the entire polymerization component of the hydroxyl group-containing acrylic resin (α). % By weight or less. When there is too much this content, bridge | crosslinking will advance before a drying process and there exists a tendency for a problem to arise in coating property.

Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.

The content of the acetoacetyl group-containing monomer is usually 10% by weight or less, preferably 5% by weight or less, more preferably 1% by weight or less, based on the entire polymerization component of the hydroxyl group-containing acrylic resin (α). is there. When there is too much this content, bridge | crosslinking will advance before a drying process and there exists a tendency for a problem to arise in coating property.

Examples of the other copolymerizable monomers (a4) include carboxylic acid vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl stearate, vinyl benzoate; phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxy Monomers containing aromatic rings such as ethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, styrene, α-methylstyrene; biphenyloxyethyl (meth) acrylate, etc. Biphenyloxy structure-containing (meth) acrylic acid ester monomers; 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, Monomers containing alkoxy groups or oxyalkylene groups such as xydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and polypropylene glycol mono (meth) acrylate; acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl vinyl ether, Examples include vinyl toluene, vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, acrylic chloride, methyl vinyl ketone, allyl trimethyl ammonium chloride, and dimethyl allyl vinyl ketone. These may be used alone or in combination of two or more.

The content of the other copolymerizable monomer (a4) is usually 40% by weight or less, preferably 30% by weight or less, more preferably 25% by weight, based on the entire polymerization component of the hydroxyl group-containing acrylic resin (α). It is as follows. When there are too many other copolymerizable monomers (a4), there exists a tendency for an adhesive characteristic to fall easily.

The hydroxyl group-containing acrylic resin (α) used in the present invention is a hydroxyl group-containing monomer (a1), an alkyl (meth) acrylate (a2), preferably a functional group-containing monomer (a3), and if necessary, other copolymerizable properties. It can be obtained by polymerizing the monomer (a4) as a polymerization component. Such a polymerization method can be suitably performed by a conventionally known method such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization or the like. Among these, production by solution radical polymerization is preferable because a hydroxyl group-containing acrylic resin (α) can be produced safely and stably with an arbitrary monomer composition.

The above-mentioned solution radical polymerization is carried out by using, for example, monomer components such as a hydroxyl group-containing monomer (a1), an alkyl (meth) acrylate (a2), a functional group-containing monomer (a3), and other copolymerizable monomers (a4) in an organic solvent. In addition, the polymerization initiator may be mixed or dropped and polymerized in a reflux state or usually at 50 to 98 ° C. for about 0.1 to 20 hours.

Examples of the organic solvent used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, n-propyl alcohol, and isopropyl alcohol. Aliphatic alcohols such as acetone, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

As the polymerization initiator, a normal radical polymerization initiator can be used, and specifically, azo polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, benzoyl peroxide, lauroyl peroxide. And peroxide polymerization initiators such as oxide, di-tert-butyl peroxide and cumene hydroperoxide.

The hydroxyl group-containing acrylic resin (α) obtained by the polymerization method is usually obtained in a solution state. The viscosity of the hydroxyl group-containing acrylic resin (α) solution at 25 ° C. is preferably 5 to 50,000 mPa · s, particularly preferably 10 to 20,000 mPa · s. When the viscosity is outside the above range, a reaction delay is caused when the hydroxyl group-containing acrylic resin (α) is reacted with the ethylenically unsaturated group carboxylic acid compound (β) or (meth) acrylic anhydride (γ). When the obtained ethylenically unsaturated group-containing acrylic resin is used as a pressure-sensitive adhesive, the coatability tends to decrease. The viscosity is measured with an E-type viscometer.

The hydroxyl group-containing acrylic resin (α) has a weight average molecular weight of usually 100,000 to 2,000,000, preferably 150,000 to 1,500,000, particularly preferably 200,000 to 1,200,000, particularly preferably 300,000 to 1,000,000. is there. If the weight average molecular weight is too small, the contamination of the workpiece tends to be high, and if it is too large, the coating property tends to be lowered, and the cost tends to be disadvantageous.

Further, the dispersity (weight average molecular weight / number average molecular weight) of the hydroxyl group-containing acrylic resin (α) is preferably 20 or less, particularly preferably 10 or less, more preferably 7 or less, especially 5 The following is preferred. If the degree of dispersion is too high, the contamination on the workpiece tends to increase. The lower limit of the degree of dispersion is usually 1.1 from the viewpoint of production limit.

The above-mentioned weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and a column: Shodex is added to a high performance liquid chromatograph (manufactured by Waters, Japan, “Waters 2695 (main body)” and “Waters 2414 (detector)”). GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / piece, filler material: styrene-divinylbenzene copolymer, filler particle size : 10 μm) are used in series, and the number average molecular weight can be obtained by the same method.

The glass transition temperature (Tg) of the hydroxyl group-containing acrylic resin (α) is usually 40 ° C. or less, preferably −70 to 20 ° C., particularly preferably −65 to 0 ° C., more preferably −60 to − 10 ° C. If the glass transition temperature is too high, the tackiness tends to decrease, and if it is too low, the contamination of the workpiece tends to increase.

The glass transition temperature (Tg) is calculated by applying the glass transition temperature and weight fraction when each monomer constituting the hydroxyl group-containing acrylic resin (α) is a homopolymer to the following Fox formula. It is the value.

Here, the glass transition temperature when the monomer constituting the hydroxyl group-containing acrylic resin (α) is a homopolymer is usually measured by a differential scanning calorimeter (DSC), such as JIS K 7121-1987. It can be measured by a method based on JIS K 6240.

Further, the acid value of the hydroxyl group-containing acrylic resin (α) is preferably 10 mgKOH / g or less, particularly 5 mgKOH / g or less, more preferably 2 mgKOH / g or less, and particularly preferably 1 mgKOH / g or less. When the above range is exceeded, gelation tends to occur during production.

The acid value of the hydroxyl group-containing acrylic resin (α) can be determined as follows.
That is, Yg of a hydroxyl group-containing acrylic resin (α) solution having a solid content of Z wt% is collected in a beaker and dissolved in a mixed solvent of toluene: methanol = 7: 3 (weight ratio). After dissolution, an appropriate amount of phenolphthalein is added, titrated with a potassium hydroxide (KOH) solution while stirring with a stirrer, and the amount of KOH solution XmL when the solution becomes light pink is read as the end point. To calculate the acid value. Normally, 0.1 mol / L is used as the KOH solution, but when the acid value of the hydroxyl group-containing acrylic resin (α) is low, a 0.01 mol / L KOH solution is used to increase the accuracy. May be.
[Formula 1]
Acid value (mgKOH / g) = X × (f × M × 56.11) / (Y × Z / 100)
F: Factor of KOH solution M: Molar concentration of KOH solution (mol / L)
-X: KOH solution amount (mL)
Y: Amount of collected hydroxyl group-containing acrylic resin (g)
Z: Solid content of hydroxyl group-containing acrylic resin (wt%)

[Ethylenically unsaturated group-containing carboxylic acid (β)]
In the present invention, the ethylenically unsaturated group-containing carboxylic acid (β) used together with the hydroxyl group-containing acrylic resin (α) can be represented as “R ⁵ —COOH”, and R ⁵ has an ethylenically unsaturated group. It is a substituent. Specific examples of the ethylenically unsaturated group-containing carboxylic acid (β) include, for example, (meth) acrylic acid, β-carboxyethyl (meth) acrylate, (meth) acrylic acid dimer, crotonic acid, maleic acid, anhydrous Examples include maleic acid, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide N-glycolic acid, and cinnamic acid. Of these, (meth) acrylic acid and β-carboxyethyl (meth) acrylate are preferred in terms of reactivity. These can be used alone or in combination of two or more.

[Compound (I)]
In the present invention, as the compound (I) used together with the hydroxyl group-containing acrylic resin (α) and the ethylenically unsaturated group-containing carboxylic acid (β), a compound represented by the following general formula (2) may be used. it can. In addition, although compound (I) represented by the following general formula (2) produces | generates the intermediate body containing the component derived from the compound by reaction, in the ethylenically unsaturated group containing acrylic resin finally obtained, The component derived from compound (I) is not included.

In the compound represented by the general formula (2), R ³ and R ⁴ each represent a hydrocarbon group. In addition, the number of carbon atoms of the hydrocarbon group is 1 to 20, preferably 2 to 10, particularly preferably 3 to 7, from the viewpoint of availability.

In the general formula (2), the type and structure of R ³ and R ⁴ are not limited as long as they are hydrocarbon groups. Specific examples of the hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. These may have any of linear, branched and cyclic structures. Moreover, an aryl group is also mentioned as said hydrocarbon group. Furthermore, these hydrocarbon groups may contain an ether bond in the structure, and R ³ and R ⁴ may be bonded to form a cyclic structure.

Specific examples of the compound (I) represented by the general formula (2) include diallyl dicarbonate, di-t-butyl dicarbonate, di-t-amyl dicarbonate, dibenzyl dicarbonate and the like. It is done. Among them, di-t-butyl dicarbonate in which R ³ and R ⁴ are t-butyl groups is preferable because an ethylenically unsaturated group-containing acrylic resin can be efficiently produced.

As the compound (I) represented by the general formula (2), a commercially available one can be used, but one obtained by a known method or the like may be used. Moreover, compound (I) may be used independently and may use 2 or more types together.

[(Meth) acrylic anhydride (γ)]
The (meth) acrylic anhydride (γ) used in the present invention is a compound represented by the following general formula (3).

[Method for producing ethylenically unsaturated group-containing acrylic resin]
The ethylenically unsaturated group-containing acrylic resin used in the present invention is
(I) a method of reacting a hydroxyl group-containing acrylic resin (α) with an ethylenically unsaturated group-containing carboxylic acid (β) in the presence of the compound (I) represented by the general formula (2),
(Ii) a method of esterifying the hydroxyl group-containing acrylic resin (α) and (meth) acrylic anhydride (γ),
Can be manufactured.
Especially, the manufacturing method of said (i) is preferable from the point of reaction efficiency.

Moreover, in each said manufacturing method, it is preferable to react in presence of the catalyst mentioned later from the point of reaction efficiency.
Here, “in the presence of a catalyst” is sufficient if the catalyst is present in at least a part of the reaction process, and does not always have to exist in all stages of the reaction process. In each of the above production methods, the requirement “in the presence of a catalyst” is satisfied if a catalyst is added to the reaction system. For example, the requirement “in the presence of the catalyst” is satisfied even if any change occurs in the catalyst during the reaction after the catalyst is added to the reaction system.

The form of the reaction vessel used for the reactions (i) and (ii) is not particularly limited. In addition, in the case of (i), the hydroxyl group-containing acrylic resin (α), the ethylenically unsaturated group-containing carboxylic acid (β) and the compound (I), and in the case of (ii), the raw material used for the reaction Containing acrylic resin (α) and (meth) acrylic anhydride (γ)], the method of introducing the catalyst, etc. into the reaction vessel is not particularly limited, for example, all the raw materials and the catalyst, etc. are put into the reaction vessel at once. Examples thereof include a method of introducing, a method of introducing some or all of the raw materials and catalysts, etc. into the reaction vessel in a stepwise manner, a method of introducing some or all of the raw materials, catalysts and the like into the reaction vessel, and the like. Moreover, you may combine these methods.
Hereinafter, each manufacturing method will be described in detail.

[Production method of (i)]
The reaction conditions in the production method (i) are not particularly limited, and the reaction conditions can be appropriately changed during the reaction process.

The amount of the ethylenically unsaturated group-containing carboxylic acid (β) used in the production method (i) is ethylenic with respect to a total of 100 mol% of the hydroxyl group-containing monomers (a1) in the hydroxyl group-containing acrylic resin (α). The unsaturated group-containing carboxylic acid (β) is usually 10 to 100 mol%, preferably 15 to 95 mol%, particularly preferably 20 to 90 mol%. If the amount of the ethylenically unsaturated group-containing carboxylic acid (β) is too small, the yield of the ethylenically unsaturated group-containing acrylic resin tends to be low, and the ethylenically unsaturated group-containing carboxylic acid (β) If the amount used is too large, the load in the post-treatment step after the reaction tends to increase, which is not economical.

The amount of the ethylenically unsaturated group-containing carboxylic acid (β) used is usually 10 to 1000 mol%, preferably 20%, based on 100 mol% of the compound (I). It is ˜500 mol%, particularly preferably 50 to 200 mol%. If the amount of the ethylenically unsaturated group-containing carboxylic acid (β) is too small, the yield of the ethylenically unsaturated group-containing acrylic resin tends to be low, and the ethylenically unsaturated group-containing carboxylic acid (β) If the amount used is too large, the load in the post-treatment step after the reaction tends to increase, which is not economical.

The reaction temperature is not particularly limited, but the production method (i) can be reacted at a relatively low temperature. The reaction temperature is usually 0 to 180 ° C., preferably 20 to 100 ° C., particularly preferably 40 to 70 ° C. If the reaction temperature is too low, the reaction efficiency tends to decrease, and if the reaction temperature is too high, there is a tendency for by-products to increase, and the ethylenically unsaturated group-containing acrylic resin tends to be colored.

The reaction time is not particularly limited, but is usually 0.5 to 72 hours, preferably 2 to 48 hours. If the reaction time is too short, the reaction tends not to proceed sufficiently, and if the reaction time is too long, the yield tends not to be improved, which is not economical.

Furthermore, in the production method (i), the atmosphere and pressure during the reaction are not particularly limited.

In the production method of (i), when the hydroxyl group-containing acrylic resin (α) and the ethylenically unsaturated group-containing carboxylic acid (β) are reacted in the presence of the compound (I), one kind of catalyst is used. It is preferable to contain the above magnesium compound and one or more alkali metal compounds. When the reaction is carried out in the presence of the catalyst, an ethylenically unsaturated group-containing acrylic resin can be obtained in a higher yield.

[Magnesium compound]
Examples of the magnesium compound include magnesium oxide, hydroxide salt, carbonate, bicarbonate, silicate, sulfate, ammonium sulfate, nitrate, phosphate, hydrogen phosphate, ammonium phosphate. , Salts with inorganic acids such as borates, halogenates, perhalogenates, hydrohalides; salts with organic acids such as carboxylates, percarboxylates, sulfonates; acetylacetone salts, Examples include hexafluoroacetylacetone salts, porphyrin salts, phthalocyanine salts, and complex salts such as cyclopentadiene salts. These magnesium salts may be either hydrates or anhydrides. Of these, oxides, hydroxide salts, carbonates, sulfates, ammonium sulfates, nitrates, hydrohalides, carboxylates and complex salts of magnesium are preferable.

More specifically, examples of the magnesium compound include magnesium oxide, magnesium hydroxide, magnesium carbonate hydroxide (also known as basic magnesium carbonate), magnesium sulfate, ammonium magnesium sulfate, magnesium nitrate, magnesium chloride, magnesium bromide, and acetic acid. Examples include magnesium, magnesium benzoate, magnesium (meth) acrylate, and magnesium acetylacetone. Of these, magnesium hydroxide is preferable.

As these magnesium compounds, commercially available ones can be used, but those obtained by producing by a known method or the like may be used. Moreover, a magnesium compound can be used individually or in combination of 2 or more types.

The amount of the magnesium compound used is not particularly limited as long as an ethylenically unsaturated group-containing acrylic resin can be produced, but is usually 0.001 to 1000 mol% with respect to the ethylenically unsaturated group-containing carboxylic acid (β). It is preferably 0.005 to 500 mol%, particularly preferably 0.01 to 250 mol%. If the amount of the magnesium compound used is too small, the effect of further increasing the yield of the ethylenically unsaturated group-containing acrylic resin tends to be difficult to obtain, and even if the amount of the magnesium compound used is too large, There is a tendency not to see the improvement, and it is not economical.

[Alkali metal compounds]
Examples of the alkali metal compounds include alkali metal hydrides, oxides, hydroxide salts, carbonates, bicarbonates, sulfates, nitrates, phosphates, borates, halogenates, peroxides, and the like. Salts with inorganic acids such as halogenates, hydrohalides and thiocyanates; Salts with organic acids such as alkoxide salts, carboxylates and sulfonates; Organic bases such as amide salts and sulfonamide salts Salt of acetylacetone, hexafluoroacetylacetone salt, porphyrin salt, phthalocyanine salt, complex salt such as cyclopentadiene salt, and the like. These alkali metal salts may be either hydrates or anhydrides. Of these, oxides, hydroxide salts, carbonates, hydrogen carbonates, hydrohalides, carboxylates, amide salts, and complex salts of alkali metals are preferable.

In addition, as the alkali metal constituting the alkali metal compound, for example, lithium, sodium, potassium, rubidium, and cesium are preferable, and the catalytic activity is high, and an ethylenically unsaturated group-containing acrylic resin can be obtained in a high yield. To lithium is more preferable.

Specific examples of the lithium compound include lithium oxide, lithium hydroxide, lithium carbonate, lithium fluoride, lithium chloride, lithium bromide, lithium acetate, lithium benzoate, lithium (meth) acrylate, and lithium amide. , Lithium triflimide, lithium acetylacetone and the like. Of these, lithium hydroxide is preferable.

As the alkali metal compound, a commercially available one can be used, but one obtained by a known method or the like can also be used. Moreover, an alkali metal compound may be used independently and may use 2 or more types together.

The amount of alkali metal compound used is not particularly limited as long as an ethylenically unsaturated group-containing acrylic resin can be produced, but is usually 0.001 to 1000 mol% with respect to the ethylenically unsaturated group-containing carboxylic acid (β). It is preferably 0.005 to 500 mol%, particularly preferably 0.01 to 250 mol%. If the amount of alkali metal compound used is too small, the effect of further increasing the yield of the ethylenically unsaturated group-containing acrylic resin tends to be difficult to obtain, and even if the amount of alkali metal compound used is too large, the yield There is a tendency not to see any further improvement, and it is not economical.

[Other optional ingredients]
Furthermore, in the production method (i), a solvent may be used as another optional component. As said solvent, the same thing as the organic solvent enumerated by manufacture of the said hydroxyl-containing acrylic resin ((alpha)) can be used. A solvent may be used individually by 1 type and 2 or more types of mixed solvents may be sufficient as it. The amount of the solvent used is not particularly limited and can be appropriately selected. The method for introducing the solvent into the reaction vessel is not particularly limited, and all the solvents may be introduced at once, or some or all of the solvents may be introduced in stages, or partly. Or all the solvents may be introduced continuously. Moreover, the introduction method which combined these methods may be sufficient.

[Production method of (ii)]
The conditions for the esterification reaction in the production method (ii) are not particularly limited, and the reaction conditions can be appropriately changed during the reaction process.

The amount of the hydroxyl group-containing acrylic resin (α) and (meth) acrylic anhydride (γ) used is (meta) with respect to 100 mol% of the hydroxyl group-containing monomer (a1) in the hydroxyl group-containing acrylic resin (α). ) Acrylic anhydride (γ) is usually 10 to 100 mol%, preferably 15 to 95 mol%, particularly preferably 20 to 90 mol%.

The reaction temperature for the esterification reaction is usually 20 to 90 ° C., preferably 30 to 80 ° C., and the reaction time is usually 2 to 40 hours, preferably 5 to 30 hours.
Furthermore, in the production method (ii), the atmosphere and pressure during the reaction are not particularly limited.

[Magnesium compound]
In the production method (ii), it is preferable to use a magnesium compound as a catalyst when the hydroxyl group-containing acrylic resin and the (meth) acrylic anhydride are esterified. As said magnesium compound, the same thing as the magnesium compound enumerated by the manufacturing method of said (i) can be used. Moreover, a magnesium compound can be used individually or in combination of 2 or more types. Of these, a salt of magnesium with an inorganic acid, a salt with an organic acid, or a complex salt is preferable, and a hydroxide, carboxylate, or acetylacetone salt of magnesium is more preferable, and magnesium hydroxide, (meth) is particularly preferable. Magnesium acrylate and magnesium acetylacetone.

The amount of the magnesium compound used is usually 0.01 to 10 mol%, preferably 0.05 to 5 mol%, particularly preferably 100 to 5 mol%, based on 100 mol% of the hydroxyl group-containing monomer (a1) in the hydroxyl group-containing acrylic resin (α). Preferably, the content is 0.1 to 1 mol%.

[Other optional ingredients]
Further, in the production method (ii), a solvent may be used as another optional component, and the same solvent as described in the polymerization of the hydroxyl group-containing acrylic resin (α) can be used. . A solvent may be used individually by 1 type and 2 or more types of mixed solvents may be sufficient as it. Further, the amount of the solvent used and the method for introducing it into the reaction vessel are the same as in the production method (i).

[Acrylic resin containing ethylenically unsaturated groups]
Thus, according to the production method of (i) or (ii), for example, an acrylic resin containing an ethylenically unsaturated group-containing structural moiety represented by the following general formula (1) can be efficiently obtained. In the following general formula, “R ¹ ” is a substituent containing an ethylenically unsaturated group.

Since the ethylenically unsaturated group-containing acrylic resin contains a predetermined amount of a specific ethylenically unsaturated group site in the side chain, it is cured by irradiating with active energy rays and has a peelability. In addition, the ethylenically unsaturated group structure site | part shown by the said General formula (1) should just be a side chain terminal of acrylic resin, for example, the said ethylenically unsaturated group containing structure site | part is in the principal chain of acrylic resin. May be directly bonded as a side chain, or the ethylenically unsaturated group-containing structural site may be bonded to the end of the side chain of the acrylic resin having a side chain. And the adhesive composition of this invention containing this ethylenically unsaturated group containing acrylic resin is excellent in the adhesive force before active energy ray irradiation, and the peelability after active energy ray irradiation. Moreover, since the ethylenically unsaturated group-containing acrylic resin does not have a carbamate group in the ethylenically unsaturated group-containing structure site, it has excellent heat resistance, and even after heating at a high temperature, after irradiation with active energy rays. Excellent peelability.

The ethylenically unsaturated group introduction rate (esterification rate) of the ethylenically unsaturated group-containing acrylic resin is usually 10% or more of the entire hydroxyl group-containing monomer (a1) in the hydroxyl group-containing acrylic resin (α), preferably Is 20% or more, particularly preferably 30% or more. The upper limit is usually 100%, and when the hydroxyl group derived from the hydroxyl group-containing monomer (a1) is used for the reaction with a crosslinking agent described later, it is preferable that 95% be the upper limit. Moreover, the upper limit of the reaction rate of ethylenically unsaturated group containing carboxylic acid ((beta)) or (meth) acrylic anhydride ((gamma)) is 100% normally. If the ethylenically unsaturated group introduction rate is too low, the peelability after irradiation with active energy rays tends to decrease. The ethylenically unsaturated group introduction rate is calculated from the integral value ratio of the hydroxyl group-containing monomer (a1) before and after the esterification reaction by ¹³ C-NMR measurement according to the following formula.

The ethylenically unsaturated group-containing acrylic resin has an ethylenically unsaturated group content of 25 to 500 mmol / 100 g with respect to the ethylenically unsaturated group-containing acrylic resin. The amount is preferably 30 to 450 mmol / 100 g, more preferably 40 to 400 mmol / 100 g, and particularly preferably 50 to 300 mmol / 100 g. If the content of ethylenically unsaturated groups is too small, the releasability of irradiation with active energy rays decreases, and if the content of ethylenically unsaturated groups is too large, the stain resistance of the workpiece after peeling decreases. .

The content of ethylenically unsaturated groups in the ethylenically unsaturated group-containing acrylic resin can be determined by the following calculation.

In addition, it is preferable that the ethylenically unsaturated group-containing acrylic resin contains a hydroxyl group because the adhesive force before irradiation with active energy rays is improved by reacting with a crosslinking agent described later to form a crosslinked structure.

The hydroxyl group content in the ethylenically unsaturated group-containing acrylic resin is usually 0.01 to 35% by weight, preferably 0.01 to 25% by weight. If the hydroxyl group content is too low, the cohesive strength of the pressure-sensitive adhesive tends to be reduced, and this tends to cause adhesive residue. If the hydroxyl group content is too high, the flexibility and adhesive strength of the pressure-sensitive adhesive are reduced, and There is a tendency that floating occurs between the workpiece and the workpiece. The hydroxyl group contained in the ethylenically unsaturated group-containing acrylic resin is a hydroxyl group-containing acrylic resin (α) and an ethylenically unsaturated group-containing carboxylic acid (β) or (meth) acrylic anhydride (γ ) And a hydroxyl group derived from the unreacted hydroxyl group-containing monomer (a1) after esterification.

Further, when the above-mentioned ethylenically unsaturated group-containing acrylic resin is used as an adhesive, a solution state is preferable. The viscosity of the ethylenically unsaturated group-containing acrylic resin solution at 25 ° C. is preferably 5 to 50,000 mPa · s, and particularly preferably 10 to 10,000 mPa · s. When the viscosity is outside the above range, the coating property tends to decrease when the ethylenically unsaturated group-containing acrylic resin is used as an adhesive. The viscosity is measured with an E-type viscometer.

[Crosslinking agent]
The pressure-sensitive adhesive composition of the present invention preferably further contains a crosslinking agent in order to improve the pressure-sensitive adhesive force before irradiation with active energy rays. As described above, the crosslinking agent reacts with a functional group in the ethylenically unsaturated group-containing acrylic resin to form a crosslinked structure. For example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent. Melamine-based crosslinking agent, aldehyde-based crosslinking agent, amine-based crosslinking agent, and metal chelate-based crosslinking agent. Among these, it is preferable to use an isocyanate-based crosslinking agent from the viewpoint of improving the adhesion to the adherend and the reactivity with the ethylenically unsaturated group-containing acrylic resin.

The isocyanate-based crosslinking agent contains at least two isocyanate groups. For example, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and isophorone diisocyanate. , Cycloaliphatic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, etc., and these biurets, isocyanurates, and low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil And adduct bodies which are reaction products. Among these, aromatic polyisocyanates, adducts of aromatic polyisocyanates and trimethylolpropane are preferable in terms of drug resistance and reactivity with functional groups, and adducts of tolylene diisocyanate and trimethylolpropane are particularly preferable. .

Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diene Examples thereof include glycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

Examples of the aziridine-based crosslinking agent include diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane tri-β-aziridinylpropionate, and tetramethylolmethanetri-β-aziridini. Lupropionate, toluene-2,4-bis (1-aziridinecarboxamide), triethylenemelamine, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) phosphine And trimethylolpropane tri-β- (2-methylaziridine) propionate.

Examples of the melamine crosslinking agent include, for example, melamine, amino group-containing methylol melamine obtained by condensing melamine and formaldehyde, methylol melamine derivatives such as imino group-containing methylol melamine, hexamethylol melamine, methylol melamine derivatives, methyl alcohol and butyl. Examples include partially or fully alkylated methylol melamine partially or completely etherified by reaction with a lower alcohol such as alcohol, alkylated methylol melamine such as imino group-containing moiety or fully alkylated methylol melamine, and the like.

Examples of the aldehyde-based crosslinking agent include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, glyoxal, glutaraldehyde, dialdehyde starch, hexamethylenetetramine, 1,4-dioxane-2,3-diol, 1,3-bis. Aldehyde compounds that liberate aldehydes in aqueous solutions such as (hydroxymethyl) -2-imidazolidine, dimethylolurea, N-methylolacrylamide, urea formalin resin, melamine formalin resin, or benzaldehyde, 2-methylbenzaldehyde, 4-methyl Aromatic aldehyde compounds such as benzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde and the like can be mentioned.

Examples of the amine crosslinking agent include 4,4'-methylene-bis (2-chloroaniline), modified 4,4'-methylene-bis (2-chloroaniline), and diethyltoluenediamine.

Examples of the metal chelate-based crosslinking agent include chelate compounds whose metal atoms are aluminum, zirconium, titanium, zinc, iron, tin and the like, and aluminum chelate compounds are preferable from the viewpoint of performance. Examples of the aluminum chelate compound include diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bis oleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetoacetate, diisopropoxy aluminum monolauryl acetoacetate, diisopropoxy Examples thereof include aluminum monostearyl acetoacetate and diisopropoxy aluminum monoisostearyl acetoacetate.

The above crosslinking agents may be used alone or in combination of two or more.

The content of the crosslinking agent is usually preferably 0.1 to 30 parts by weight, particularly preferably 0.2 to 20 parts by weight, based on 100 parts by weight of the ethylenically unsaturated group-containing acrylic resin. More preferably, it is 0.2 to 15 parts by weight. If the amount of the crosslinking agent is too small, the cohesive force of the pressure-sensitive adhesive tends to decrease and causes adhesive residue. If the amount is too large, the flexibility and pressure-sensitive adhesive strength of the pressure-sensitive adhesive decreases and floats between the workpiece. Tend to occur.

(Photopolymerization initiator)
The pressure-sensitive adhesive composition of the present invention preferably contains a photopolymerization initiator from the viewpoint of improving the peelability after irradiation with active energy rays. The photopolymerization initiator is not particularly limited as long as it generates radicals by the action of light, and examples thereof include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4 -(2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenylketone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl- 1-propan-1-one, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone, 2- ( Dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) pheny ] -1-butanone, acetophenone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer;
Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether;
Benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3 ', 4,4'-tetra (tert-butylperoxycarbonyl) benzophenone, 2,4 , 6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethananium bromide, (4-benzoylbenzyl) trimethylammonium chloride, etc. Benzophenones;
2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy) -3,4- Thioxanthones such as dimethyl-9H-thioxanthone-9-one mesochloride;
2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenyl Acylphosphine oxides such as phosphine oxide;
Etc. Among these, acetophenones, particularly 1-hydroxycyclohexyl phenyl ketone, and thioxanthones, particularly 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, are preferable.
In addition, these photoinitiators can be used individually or can use 2 or more types together.

The content of the photopolymerization initiator is preferably 0.1 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated group-containing acrylic resin. Particularly preferred is 0.5 to 10 parts by weight.
If the content of the photopolymerization initiator is too low, the curability of the ethylenically unsaturated group-containing acrylic resin is low during irradiation with active energy rays, and the peelability after irradiation with active energy rays tends to be low. If the amount is too large, the contamination on the workpiece tends to increase.

Examples of auxiliary agents for these photopolymerization initiators include triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, Ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2, 4-diisopropylthioxanthone or the like can be used in combination. These auxiliaries can be used alone or in combination of two or more.

[Other ingredients]
In the pressure-sensitive adhesive composition of the present invention, it is preferable that, for example, an ethylenically unsaturated compound is blended from the viewpoint of releasability after irradiation with active energy rays, as long as the effects of the present invention are not impaired. In addition, additives such as antioxidants, plasticizers, fillers, pigments, diluents, anti-aging agents, ultraviolet absorbers, ultraviolet stabilizers, and tackifying resins may be further contained. These additives can be used alone or in combination of two or more. In particular, the antioxidant is effective for maintaining the stability of the pressure-sensitive adhesive layer. The content when the antioxidant is blended is not particularly limited, but is preferably 0.01 to 5% by weight. In addition to the additives, a small amount of impurities contained in the raw materials for producing the constituent components of the pressure-sensitive adhesive composition may be contained.

Thus, the pressure-sensitive adhesive composition of the present invention can be obtained by mixing an ethylenically unsaturated group-containing acrylic resin, preferably a crosslinking agent, a photopolymerization initiator, and other components as required.

The pressure-sensitive adhesive composition of the present invention is cross-linked by the above-mentioned cross-linking agent and exhibits performance as a pressure-sensitive adhesive. After that, by irradiating with active energy rays, the ethylenic unsaturated group-containing acrylic resin has ethylenic properties. The unsaturated group is polymerized, the pressure-sensitive adhesive is cured, and the peel strength is reduced.

The pressure-sensitive adhesive composition of the present invention is usually a pressure-sensitive adhesive for pressure-sensitive adhesive sheets for temporarily protecting the surface when processing a workpiece such as an electronic substrate, a semiconductor wafer, a glass processed product, a metal plate, or a plastic plate. It is preferably used as a layer. In addition, since the pressure-sensitive adhesive sheet of the present invention is excellent in heat resistance, even when it is subjected to a heating step of 100 ° C. or higher after being attached to the surface of the workpiece, by irradiating with active energy rays, Exhibits excellent peelability.
Hereinafter, the said adhesive sheet is demonstrated.

The above-mentioned pressure-sensitive adhesive sheet usually has a substrate sheet, a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition of the present invention, and a release film. As a method for producing such a pressure-sensitive adhesive sheet, first, the pressure-sensitive adhesive composition of the present invention is directly applied to a release film or a base sheet by adjusting the concentration as it is or with an appropriate organic solvent. Thereafter, the pressure-sensitive adhesive sheet can be obtained by drying, for example, by heat treatment at 80 to 105 ° C. for 0.5 to 10 minutes, and affixing this to a base sheet or a release film. Moreover, in order to balance an adhesive physical property, you may age further after drying.

Examples of the base sheet include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride Polyvinyl fluoride resins such as polyvinylidene fluoride and polyvinyl fluoride; polyamides such as nylon 6 and nylon 6, 6; polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene- Vinyl polymers such as vinyl alcohol copolymer, polyvinyl alcohol and vinylon; Cellulosic resins such as cellulose triacetate and cellophane; Polymethyl methacrylate, Polyethyl methacrylate, Polyacryl Acrylic resins such as ethyl and polybutyl acrylate; polystyrene; polycarbonate; polyarylate; synthetic resin sheets such as polyimide, aluminum, copper, iron metal foil, fine paper, glassine paper, glass fiber, natural fiber, Examples include woven fabrics and nonwoven fabrics made of synthetic fibers. These base material sheets can be used as a single layer body or a multilayer body in which two or more kinds are laminated. Among these, a synthetic resin sheet is preferable from the viewpoint of weight reduction.

Furthermore, as the release film, for example, various synthetic resin sheets exemplified in the base sheet, paper, woven fabric, nonwoven fabric, and the like can be used.

In addition, the application method of the pressure-sensitive adhesive composition is not particularly limited as long as it is a general application method, and examples thereof include roll coating, die coating, gravure coating, comma coating, and screen printing. Can be mentioned.

The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is usually preferably 10 to 200 μm, more preferably 15 to 100 μm.

As conditions for the above aging, the temperature is usually from room temperature (23 ° C.) to 70 ° C., the time is usually from 1 to 30 days, and specifically, for example, at 23 ° C. for 1 to 20 days and at 23 ° C. for 3 to 3 days. The treatment may be performed for 10 days at 40 ° C. for 1 to 7 days.

The pressure-sensitive adhesive sheet of the present invention is one whose adhesive strength is reduced by irradiating with active energy rays. The active energy rays are usually rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, and X-rays. In addition to electromagnetic waves such as γ rays, electron beams, proton beams, neutron beams and the like can be used. Among these, ultraviolet rays are preferable from the viewpoint of curing speed, availability of the irradiation apparatus, price, and the like.

In the case of irradiating with the ultraviolet rays, the integrated irradiation amount is usually 50 to 3,000 mJ / cm ² , preferably 100 to 1,000 mJ / cm ² . The irradiation time varies depending on the type of light source, the distance between the light source and the pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer, and other conditions, but it may be usually several seconds, and in some cases, may be a fraction of a second.

The pressure-sensitive adhesive strength of the pressure-sensitive adhesive sheet varies depending on the type of substrate sheet, the type of workpiece, etc., but is preferably 0.1 to 30 N / 25 mm before irradiation with active energy rays, and more preferably 0.5 to 20 N / 25 mm is preferred. The adhesive strength after irradiation with active energy rays is preferably 1 N / 25 mm or less, and more preferably 0.5 N / 25 mm or less.
The adhesive strength after irradiation with the active energy ray is preferably 1/10 or less, more preferably 1/20 or less of the adhesive strength before active energy ray irradiation.

The pressure-sensitive adhesive sheet of the present invention preferably has an adhesive strength of 1 N / 25 mm or less when heated at 150 ° C. for 1 hour and then subjected to ultraviolet irradiation (integrated irradiation amount: 250 mJ / cm ² ). It is preferable that it is 0.5 N / 25 mm or less.
When heated at 150 ° C. for 1 hour, the adhesive strength after irradiation with active energy rays is preferably 1/5 or less, more preferably 1/10 or less of the adhesive strength before irradiation with active energy rays.

Furthermore, the pressure-sensitive adhesive sheet of the present invention preferably has an adhesive strength of 2 N / 25 mm or less when heated at 200 ° C. for 1 hour and then subjected to ultraviolet irradiation (integrated irradiation amount: 250 mJ / cm ² ). It is preferably 1 N / 25 mm or less.
When heated at 200 ° C. for 1 hour, the adhesive strength after irradiation with active energy rays is preferably 1/2 or less, more preferably 1/3 or less of the adhesive strength before irradiation with active energy rays.

The pressure-sensitive adhesive composition of the present invention includes, for example, an adhesive sheet using the pressure-sensitive adhesive layer as a pressure-sensitive adhesive layer and a member to be processed, and temporarily protecting the surface of the member to be processed. , The pressure-sensitive adhesive layer is cured and the adhesive strength is reduced, and can be easily peeled off from the workpiece. Furthermore, since the pressure-sensitive adhesive sheet of the present invention is excellent in heat resistance, it is applied to a heating step of, for example, 100 ° C. or higher, particularly 150 ° C. or higher after being attached to the surface of the workpiece. However, it exhibits excellent releasability by irradiation with active energy rays thereafter.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following, “part” means a weight basis.

<Preparation of hydroxyl group-containing acrylic resin (α) and carboxy group-containing acrylic resin (α ′)>
Prior to the examples, a hydroxyl group-containing acrylic resin (α) and a carboxy group-containing acrylic resin (α ′) were prepared.

[Preparation Example 1]
After charging ethyl acetate and azobisisobutyronitrile (AIBN) into a 2 L round bottom four-neck flask and refluxing, butyl acrylate (BA) and 2-hydroxyethyl acrylate (2HEA) were added dropwise over 2 hours. Then, ethyl acetate and AIBN were appropriately added and reacted for 7.5 hours to obtain a hydroxyl group-containing acrylic resin (α-1) solution.
The monomer composition of the hydroxyl group-containing acrylic resin (α-1) is BA / 2HEA = 72/28 (weight ratio), the weight average molecular weight is 470,000, the glass transition temperature is −23.7 ° C., the solid content Was 45.7 wt%, and the viscosity was 12,600 mPa · s / 25 ° C. The acid value of the hydroxyl group-containing acrylic resin (α-1) was 0.09 mgKOH / g.

[Preparation Example 2]
A 2 L round bottom four-necked flask was charged with ethyl acetate and azobisisobutyronitrile (AIBN), and refluxed while adding butyl acrylate (BA), methyl methacrylate (MMA), and 2-hydroxyethyl acrylate (2HEA). After dropwise addition over time, ethyl acetate and AIBN were appropriately added and reacted for 7.5 hours to obtain a hydroxyl group-containing acrylic resin (α-2) solution.
The monomer composition of the hydroxyl group-containing acrylic resin (α-2) is BA / MMA / 2HEA = 62/10/28 (weight ratio), the weight average molecular weight is 600,000, and the glass transition temperature is −35.3 ° C. The solid content was 40% by weight and the viscosity was 6,000 mPa · s / 25 ° C. The acid value of the hydroxyl group-containing acrylic resin (α-2) was 0.09 mgKOH / g.

[Preparation Example 3]
Into a 2 L round bottom four-necked flask, ethyl acetate and azobisisobutyronitrile (AIBN) are charged, and while refluxing, butyl acrylate (BA) and acrylic acid (AAc) are added dropwise over 2 hours, and then acetic acid is appropriately added. Ethyl and AIBN were added and reacted for 7.5 hours to obtain a carboxy group-containing acrylic resin (α′-1) solution.
The monomer composition of the carboxy group-containing acrylic resin (α′-1) is BA / AAc = 80/20 (weight ratio), the weight average molecular weight is 710,000, the glass transition temperature is −35.7 ° C., The solid content was 35.0% by weight and the viscosity was 15,000 mPa · s / 25 ° C. The acid value of the carboxy group-containing acrylic resin (α′-1) was 156 mgKOH / g.

Using the hydroxyl group-containing acrylic resin (α) and carboxy group-containing acrylic resin (α ′) obtained above, an ethylenically unsaturated group-containing acrylic resin was produced.

<Production Example 1>
In a 2 L round bottom four-necked flask, 80 mol% of acrylic acid containing the hydroxyl group-containing acrylic resin (α-1) prepared above and 100 mol% of the hydroxyl group-containing monomer in the hydroxyl group-containing acrylic resin (α-1) was added. (AAc) (β-1) and 0.50 mol% magnesium hydroxide and 0.50 mol% lithium hydroxide were charged to acrylic acid, respectively, and the temperature was raised to 60 ° C. while stirring. Next, a 50% toluene solution of di-t-butyl dicarbonate (I-1) in the same mol as the charged acrylic acid was added dropwise over 6 hours, and the mixture was further reacted at 60 ° C. for 10 hours. A resin (1) was obtained. During the reaction, no significant increase in viscosity was observed, and the reaction proceeded well.
The obtained ethylenically unsaturated group-containing acrylic resin (1) had a solid content of 34.4% by weight and a viscosity of 2,300 mPa · s / 25 ° C., and the esterification rate calculated from the results of ¹³ C-NMR measurement. Was 76.9% (reaction rate was 96.1%), and the content of ethylenically unsaturated groups was 165 mmol / 100 g.

<Production Example 2>
In a 2 L round bottom four-necked flask, 80 mol% of methacrylic resin (α-2) prepared above and 100 mol% of the hydroxyl group-containing monomer in the hydroxyl group-containing acrylic resin (α-2) were added. An acid anhydride (γ-1) and 0.40 mol% of magnesium hydroxide as an esterification catalyst were charged and reacted at 50 ° C. with stirring for 18 hours to obtain an ethylenically unsaturated group-containing acrylic resin (2).
The obtained ethylenically unsaturated group-containing acrylic resin (2) had a solid content of 31.8% by weight and a viscosity of 800 mPa · s / 25 ° C. The esterification rate calculated from the result of ¹³ C-NMR measurement was 64 % (Reaction rate was 80%), and the content of ethylenically unsaturated groups was 140 mmol / 100 g.

<Production Example 3>
In Production Example 2, 33 mol% of methacrylic anhydride (γ-1) and 0.16 mol of magnesium hydroxide as an esterification catalyst with respect to 100 mol% of the hydroxyl group-containing monomer in the hydroxyl group-containing acrylic resin (α-2). An ethylenically unsaturated group-containing acrylic resin (3) was obtained in the same manner as in Production Example 2, except that the percentage was changed to%.
The obtained ethylenically unsaturated group-containing acrylic resin (3) had a solid content of 31.9% by weight and a viscosity of 1,000 mPa · s / 25 ° C., and the esterification rate calculated from the results of ¹³ C-NMR measurement. Was 33% (reaction rate was 100%), and the content of ethylenically unsaturated groups was 72 mmol / 100 g.

<Production Example 4>
With respect to 100 mol% of the hydroxyl group-containing monomer in the hydroxyl group-containing acrylic resin (α-2) obtained in Preparation Example 2, 80 mol% of 2-methacryloyloxyethyl acrylate (MOI) and dibutyltin dilaurate as a urethanization catalyst were used. It added suitably and made it react at 50 degreeC for 18 hours, and obtained ethylenically unsaturated group containing acrylic resin (1 ').
The obtained ethylenically unsaturated group-containing acrylic resin (1 ′) has a solid content of 35.0% by weight and a viscosity of 1,200 mPa · s / 25 ° C., and urethanization calculated from the results of ¹³ C-NMR measurement. The rate was 80% (reaction rate was 100%), and the content of ethylenically unsaturated groups was 148 mmol / 100 g.

<Production Example 5>
In Production Example 2, 8.4 mol% of methacrylic anhydride (γ-1) and magnesium hydroxide as an esterification catalyst were 0 with respect to 100 mol% of the hydroxyl group-containing monomer in the hydroxyl group-containing acrylic resin (α-2). An ethylenically unsaturated group-containing acrylic resin (2 ′) was obtained in the same manner as in Production Example 2, except that the amount was changed to 0.04 mol%.
The obtained ethylenically unsaturated group-containing acrylic resin (2 ′) had a solid content of 31.4% by weight and a viscosity of 1,500 mPa · s / 25 ° C., and was esterified as calculated from the results of ¹³ C-NMR measurement. The rate was 8.4% (reaction rate was 100%), and the content of ethylenically unsaturated groups was 20 mmol / 100 g.

<Production Example 6>
In a 2 L round bottom four-necked flask, the carboxy group-containing acrylic resin (α′-1) prepared above and 100 mol% of the carboxy group-containing monomer in the carboxy group-containing acrylic resin (α′-1) 80 mol% of 2HEA and 2 HEA were charged with 0.50 mol% of magnesium hydroxide and 0.50 mol% of lithium hydroxide, respectively, and the temperature was raised to 60 ° C. while stirring. Next, a 50% toluene solution of di-t-butyl dicarbonate (I-1) in the same mol as 2HEA charged was dropped over 6 hours. The viscosity gradually increased immediately after the start of dropping, and it was difficult to continue the reaction.

The presence or absence of carbamate groups and the content of ethylenically unsaturated groups in the ethylenically unsaturated group-containing acrylic resins obtained in Production Examples 1 to 6 are shown in Table 1 below.

<Example 1>
Photopolymerization of 1.0 part of an isocyanate-based crosslinking agent (“Coronate L-55E” manufactured by Nippon Polyurethane Co., Ltd.) with respect to 100 parts of the solid content of the ethylenically unsaturated group-containing acrylic resin (1) obtained above. An initiator (“Irgacure 184” manufactured by BASF) was mixed with 3.00 parts to prepare an active energy ray-curable pressure-sensitive adhesive composition. The formulation of Example 1 is shown in Table 2 below.

<Examples 2 and 3 and Comparative Examples 1 and 2>
In Example 1, the types of the ethylenically unsaturated group-containing acrylic resin, the isocyanate cross-linking agent and the photopolymerization initiator were blended according to Table 2 below and mixed, whereby Examples 2, 3 and Comparative Examples 1, 2 The active energy ray-curable pressure-sensitive adhesive composition was prepared.

The adhesive compositions of Examples 1 to 3 and Comparative Examples 1 and 2 were applied on a polyimide film (film thickness 50 μm) (“Kapton 200H” manufactured by Toray DuPont) so that the thickness after drying was 25 μm. It was dried and attached to a 38 μm separator (“SP-PET 38 01-BU” manufactured by Mitsui Chemicals, Inc.) and aged at 40 ° C. for 3 days to prepare an adhesive sheet.
The following evaluation was performed about the obtained adhesive sheet. The evaluation results are shown in Table 2 below.

<Adhesive strength before irradiation with active energy rays>
A test piece of 25 mm × 100 mm was prepared from the pressure-sensitive adhesive sheet obtained above, the separator was peeled off, and a rubber roller having a weight of 2 kg was reciprocated twice in an atmosphere of 23 ° C. and 50% RH on a Corning glass plate. After applying pressure and allowing to stand for 30 minutes in the same atmosphere, 180 degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min. The evaluation criteria are as follows.
(Evaluation criteria)
◎ ・ ・ ・ 6.0N / 25mm or more ○ ・ ・ ・ 3.0N / 25mm or more, less than 6.0N / 25mm × ・ ・ ・ 3.0N / 25mm or less

<Adhesive strength after irradiation with active energy rays>
A test piece of 25 mm × 100 mm was prepared from the pressure-sensitive adhesive sheet obtained above, the separator was peeled off, and a rubber roller having a weight of 2 kg was reciprocated twice in an atmosphere of 23 ° C. and 50% RH on a Corning glass plate. After applying pressure and allowing to stand in the same atmosphere for 30 minutes, using one 80 W high-pressure mercury lamp, the glass plate was irradiated with ultraviolet rays (integrated irradiation amount 250 mJ / cm ² ) and immediately peeled off at a rate of 300 mm / min. 180 degree peel strength (N / 25mm) was measured. The evaluation criteria are as follows.
(Evaluation criteria)
◎ ・ ・ ・ less than 0.1N / 25mm ○ ・ ・ ・ 0.1N / 25mm or more, 1N / 25mm or less × ・ ・ ・ greater than 1N / 25mm

<Adhesive strength after heating and irradiation with active energy rays (150 ° C)>
A test piece of 25 mm × 100 mm was prepared from the pressure-sensitive adhesive sheet obtained above, the separator was peeled off, and a rubber roller having a weight of 2 kg was reciprocated twice in an atmosphere of 23 ° C. and 50% RH on a Corning glass plate. This was put into an oven jet dryer that had been pressure-applied and heated to 150 ° C. for 1 hour. After removing from the dryer and cooling in an atmosphere of 23 ° C. and 50% RH for 30 minutes, an ultraviolet ray irradiation (integrated irradiation amount 250 mJ / cm ² ) was applied from the glass plate side using one 80 W high-pressure mercury lamp, The 180 degree peel strength (N / 25 mm) was immediately measured at a peel speed of 300 mm / min. Further, the adherend after peeling was visually confirmed to evaluate the stain resistance. The evaluation criteria are as follows.
(Evaluation criteria: Adhesive strength)
◎ ・ ・ ・ less than 0.5N / 25mm ○ ・ ・ ・ 0.5N / 25mm or more, 1.0N / 25mm or less × ・ ・ ・ greater than 1.0N / 25mm (evaluation criteria: contamination resistance)
◎ ・ ・ ・ No glue residue ○ ・ ・ ・ Slight adhesive residue × ・ ・ ・ Full surface adhesive residue

<Adhesive strength after heating and irradiation with active energy rays (200 ° C)>
A test piece of 25 mm × 100 mm was prepared from the pressure-sensitive adhesive sheet obtained above, the separator was peeled off, and a rubber roller having a weight of 2 kg was reciprocated twice in an atmosphere of 23 ° C. and 50% RH on a Corning glass plate. The sample was put into an oven jet dryer that had been pressure-applied and heated to 200 ° C. for 1 hour. After removing from the dryer and cooling in an atmosphere of 23 ° C. and 50% RH for 30 minutes, an ultraviolet ray irradiation (integrated irradiation amount 250 mJ / cm ² ) was applied from the glass plate side using one 80 W high-pressure mercury lamp, The 180 degree peel strength (N / 25 mm) was immediately measured at a peel speed of 300 mm / min. Further, the adherend after peeling was visually confirmed to evaluate the stain resistance. The evaluation criteria are as follows.
(Evaluation criteria: Adhesive strength)
◎ ・ ・ ・ less than 0.5N / 25mm ○ ・ ・ ・ 0.5N / 25mm or more, 2.0N / 25mm or less × ・ ・ ・ 2.0N / 25mm or more (evaluation criteria: contamination resistance)
◎ ・ ・ ・ No glue residue ○ ・ ・ ・ Slight adhesive residue × ・ ・ ・ Full surface adhesive residue

As can be seen from Table 2 above, the products of Examples 1 to 3, which contain an ethylenically unsaturated group-containing acrylic resin having a specific amount of a specific ethylenically unsaturated group-containing structural site in the side chain, are before irradiation with active energy rays. It was excellent in adhesive strength and peelability after irradiation with active energy rays.
Further, the products of Examples 1 to 3 were excellent in anti-contamination property by decreasing the adhesive strength by irradiation with active energy rays even after heating at 150 ° C. and 200 ° C.
On the other hand, Comparative Example 1 using an acrylic resin having no specific ethylenically unsaturated group-containing structure site has high adhesive strength before irradiation with active energy rays and low adhesive strength after irradiation with active energy rays. However, the adhesive strength after heating was high and the stain resistance was poor. Furthermore, Comparative Example 2 using an acrylic resin that does not contain a specific amount of a specific ethylenically unsaturated group-containing structure site has high adhesive strength after irradiation with active energy rays and adhesive strength after heating, and is inferior in peelability. Met.

In the above embodiments, specific forms in the present invention have been described. However, the above embodiments are merely examples and are not construed as limiting. Various modifications apparent to those skilled in the art are contemplated to be within the scope of this invention.

The pressure-sensitive adhesive composition of the present invention can be suitably used as a pressure-sensitive adhesive composition for temporary protective films for surface protection when processing electronic substrates, semiconductor wafers, glass processed products, metal plates, plastic plates, and the like. it can.

Claims (17)

The side chain of the acrylic resin contains an ethylenically unsaturated group-containing structural site represented by the following general formula (1), and the ethylenically unsaturated group content in the ethylenically unsaturated group-containing acrylic resin A pressure-sensitive adhesive composition comprising an ethylenically unsaturated group-containing acrylic resin in an amount of 25 to 500 mmol / 100 g.

The pressure-sensitive adhesive composition according to claim 1, wherein the ethylenically unsaturated group-containing acrylic resin contains a hydroxyl group. The pressure-sensitive adhesive composition according to claim 1 or 2, further comprising a crosslinking agent. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, further comprising a photopolymerization initiator. The presence of the compound (I) represented by the following general formula (2), wherein the ethylenically unsaturated group-containing acrylic resin is a hydroxyl group-containing acrylic resin (α) and an ethylenically unsaturated group-containing carboxylic acid (β). The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive composition is reacted under the following conditions.

The ethylenically unsaturated group-containing acrylic resin is obtained by esterification of a hydroxyl group-containing acrylic resin (α) and (meth) acrylic anhydride (γ). The pressure-sensitive adhesive composition according to any one of 4. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition according to any one of claims 1 to 6. The pressure-sensitive adhesive sheet according to claim 7, wherein the pressure-sensitive adhesive layer is cured and can be peeled by irradiation with active energy rays. The pressure-sensitive adhesive sheet according to claim 7 or 8, wherein the pressure-sensitive adhesive sheet is subjected to a heating step of 150 ° C or higher after the pressure-sensitive adhesive sheet is attached to the adherend surface. An ethylenically unsaturated resin characterized by reacting a hydroxyl group-containing acrylic resin (α) with an ethylenically unsaturated group-containing carboxylic acid (β) in the presence of the compound (I) represented by the following general formula (2). A method for producing a saturated group-containing acrylic resin.

When the hydroxyl group-containing acrylic resin (α) and the ethylenically unsaturated group-containing carboxylic acid (β) are reacted in the presence of the compound (I) represented by the general formula (2), one or more types are further reacted. The method for producing an ethylenically unsaturated group-containing acrylic resin according to claim 10, wherein the reaction is carried out in the presence of one or more alkali metal compounds. The method for producing an ethylenically unsaturated group-containing acrylic resin according to claim 11, wherein the alkali metal constituting the alkali metal compound is lithium. The ethylenically unsaturated group-containing acrylic system according to any one of claims 10 to 12, wherein the compound (I) represented by the general formula (2) is di-t-butyl dicarbonate. Manufacturing method of resin. 12. The reaction with the ethylenically unsaturated group-containing carboxylic acid (β) in the presence of 0.001 to 1000 mol% of the magnesium compound and 0.001 to 1000 mol% of the alkali metal compound. 14. The method for producing an ethylenically unsaturated group-containing acrylic resin according to any one of items 1 to 13. 15. The content of the hydroxyl group-containing monomer (a1) constituting the hydroxyl group-containing acrylic resin (α) is from 0.1 to 50% by weight based on the entire polymerization component. A method for producing an ethylenically unsaturated group-containing acrylic resin according to claim 1. The ethylenically unsaturated group content of the ethylenically unsaturated group-containing acrylic resin is 25 to 500 mmol / 100 g with respect to the ethylenically unsaturated group-containing acrylic resin. The manufacturing method of ethylenically unsaturated group containing acrylic resin as described in any one of these. The method for producing an ethylenically unsaturated group-containing acrylic resin according to any one of claims 10 to 16, wherein the hydroxyl group-containing acrylic resin (α) has an acid value of 10 mgKOH / g or less.