JP7251202B2 - Active energy ray-curable peelable pressure-sensitive adhesive composition and peelable pressure-sensitive adhesive sheet - Google Patents

Description

The present invention relates to active energy used in the adhesive layer of a peelable adhesive sheet for temporary surface protection when processing workpieces such as semiconductor wafers, printed circuit boards, glass processed products, metal plates, and plastic plates. The present invention relates to a radiation-curable peelable pressure-sensitive adhesive composition and a peelable pressure-sensitive adhesive sheet.

A urethane (meth)acrylate-based compound can be obtained by reacting a polyvalent isocyanate-based compound with a hydroxyl group-containing (meth)acrylate-based compound. In such reactions, various catalysts are used to efficiently obtain urethane (meth)acrylate compounds. Examples of the catalyst include organometallic compounds, organic amines, salts thereof, and the like. Among these, dibutyltin dilaurate (DBTL) is generally used because of its high catalytic ability.

Active energy ray-curable peel-type pressure-sensitive adhesives using the above urethane (meth)acrylate compounds and acrylic resins are also known. For example, in Patent Document 1, a pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive and a radiation-polymerizable compound, which is a urethane acrylate-based oligomer having a weight average molecular weight of 3,000 to 10,000, is applied on the substrate surface. A pressure-sensitive adhesive sheet is disclosed. Further, it is described that when the sheet is peeled off, the adhesive force to the adherend is abruptly reduced by irradiating the sheet with ultraviolet rays.

Conventionally, the adhesive sheet temporarily protects the surface of the workpiece for the purpose of preventing contamination and damage to the workpiece in processing steps such as manufacturing integrated circuits using semiconductor wafers and drilling holes. It is used as a surface protection for In recent years, due to the miniaturization of processing technology and the thinning of processed materials, an appropriate amount of adhesive strength is required for processed materials. It is necessary to peel off the sheet, and it is required that the sheet can be peeled off with a light force without leaving an adhesive residue. Moreover, in recent years, adhesive sheets for surface protection are used not only for semiconductor wafers but also for processing various members.

Under such circumstances, for example, in Patent Document 2, the peelability (stain resistance, slight adhesiveness) of the adhesive sheet after irradiation with active energy rays is adjusted by the type and blending ratio of the radiation polymerizable compound and the number of acryloyl groups. known to do.

In addition, in the manufacturing process of electronic components in recent years, the parts to which the adhesive tape is attached are increasingly exposed to high temperatures. Heat resistance is also required.

JP-A-62-153376 JP-A-7-193028

The technology disclosed in Patent Document 1 describes that the adhesive strength before irradiation with active energy rays is good. However, with the recent miniaturization of processing technology, a higher adhesive strength before active energy ray irradiation is required than before, and the disclosed technology of Patent Document 1 obtains a sufficiently satisfactory adhesive strength before active energy ray irradiation. is considered difficult.

In addition, in the technology disclosed in Patent Document 2, when a radiation-polymerizable compound and an acrylic resin are used, the acrylic resin is plasticized by the radiation-polymerizable compound, and the adhesive strength before irradiation with active energy rays decreases. There is a problem that the adhesive may be left behind.

Furthermore, by lowering the glass transition temperature of the acrylic resin, it is possible to reduce the adhesive strength after irradiation with active energy rays after the heating process, but the adhesive strength before irradiation with active energy rays is low, and further improvement is required. there is

Therefore, in the present invention, under such a background, the adhesive strength before active energy ray irradiation is good, and the adhesive is excellent in heat resistance, and the peelability after active energy ray irradiation (resistant) even after heating. An object of the present invention is to provide an active energy ray-curable peelable pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive excellent in stain resistance and slight tackiness.

However, as a result of intensive research in view of such circumstances, the present inventors have developed an active energy ray-curable peelable pressure-sensitive adhesive composition containing an acrylic resin having a low glass transition temperature and a urethane (meth)acrylate compound. , By containing a small amount of a bismuth-based compound, the adhesive strength before irradiation with active energy rays is high, and the adhesive strength after irradiation with active energy rays after the heating process can be reduced, resulting in excellent peelability. completed the invention.

In general, the adhesive strength before irradiation with an active energy ray is considered to be greatly affected by the composition of the acrylic resin, the glass transition temperature, and the amount of the cross-linking agent. The effect of increasing the adhesive strength before irradiation was found.

That is, the present invention provides an active energy ray-curable peelable pressure-sensitive adhesive composition containing an acrylic resin (A), a urethane (meth)acrylate compound (B) and a bismuth compound (C), wherein the acrylic The glass transition temperature of the resin (A) is −10° C. or less, and the content of the bismuth compound (C) is 1× in terms of bismuth element with respect to 100 parts by weight of the acrylic resin (A). A first gist is an active energy ray-curable peelable pressure-sensitive adhesive composition containing 10 ^-5 to 1 part by weight. A second aspect of the present invention is a peelable pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the active energy ray-curable peelable pressure-sensitive adhesive composition of the first aspect is crosslinked.

The present invention provides an active energy ray-curable peelable pressure-sensitive adhesive composition containing an acrylic resin (A), a urethane (meth)acrylate compound (B) and a bismuth compound (C), wherein the acrylic resin (A) has a glass transition temperature of −10° C. or less, and the content of the bismuth compound (C) is 1×10 ⁻ in terms of bismuth element per 100 parts by weight of the acrylic resin (A). ⁵ to 1 part by weight. Therefore, when this active energy ray-curable peelable pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive layer of a peelable pressure-sensitive adhesive sheet, the adhesive strength before irradiation with active energy rays is good, and the heat resistance is excellent. , even after heating, it can be made excellent in releasability (stain resistance, slight adhesiveness) after irradiation with active energy rays.

Furthermore, when the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention contains the cross-linking agent (D), the adhesive strength before irradiation with active energy ray becomes more excellent.

Furthermore, when the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator (E), the curability of the urethane (meth)acrylate compound (B) is improved by irradiation with active energy rays, It becomes more excellent in releasability after irradiation with active energy rays.

When the content of the bismuth-based compound (C) is 1×10 ^-5 to 1 part by weight in terms of bismuth element with respect to 100 parts by weight of the urethane (meth)acrylate-based compound (B), more active energy rays It has excellent adhesive strength before irradiation.

EMBODIMENT OF THE INVENTION 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 acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate, respectively.
Further, "acrylic resin" is a resin obtained by polymerizing a polymerizable component containing at least one (meth)acrylate monomer.
In the present invention, the term "sheet" is not particularly distinguished from "film" and "tape", but is used to include these.

The active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention is usually used mainly for the pressure-sensitive adhesive layer of a peelable pressure-sensitive adhesive sheet, which is intended to be peeled after being bonded to a workpiece once. The peelable pressure-sensitive adhesive sheet is used in a state in which an active energy ray-curable peelable pressure-sensitive adhesive composition is applied onto a base sheet to form a pressure-sensitive adhesive layer. By irradiating with , the adhesive layer is cured, the adhesive strength is lowered, and it can be easily peeled off from the workpiece.

The active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention comprises an acrylic resin (A), a urethane (meth)acrylate compound (B) and a bismuth compound (C). Each component will be described below.

[Acrylic resin (A)]
The acrylic resin (A) used in the present invention comprises a (meth)acrylic acid alkyl ester monomer (a1), a functional group-containing monomer (a2), and optionally other copolymerizable monomers (a3). It is obtained by copolymerization.

The (meth)acrylic acid alkyl ester monomer (a1) is the main component of the acrylic resin (A). In the (meth)acrylic acid alkyl ester-based monomer (a1), the number of carbon atoms in the alkyl group is usually 1 to 20, preferably 1 to 12, particularly preferably 1 to 8, and more preferably 1 to 4. . If the number of carbon atoms is too large, the resulting acrylic resin (A) and urethane (meth)acrylate compound (B) will be difficult to mix uniformly, tending to leave adhesive residue on the workpiece.

Specific examples of the (meth)acrylic acid alkyl ester-based monomer (a1) include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 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 ( Aliphatic (meth)acrylic acid alkyl ester monomers such as meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. Examples thereof include alicyclic (meth)acrylic acid alkyl ester-based monomers. These may be used independently and may use 2 or more types together.
Among the (meth)acrylic acid alkyl ester-based monomers (a1), aliphatic (meth)acrylic acid alkyl ester-based monomers are preferable, in terms of copolymerizability, adhesive physical properties, ease of handling, and ease of raw material availability. Methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are particularly preferably used.

The content of the (meth)acrylic acid alkyl ester monomer (a1) in the polymerization component is usually 30 to 99.9% by weight, preferably 40 to 99% by weight, and particularly preferably 50 to 98% by weight. %. If the content is too small, the adhesive strength before irradiation with active energy rays tends to decrease, and if it is too large, the adhesive strength before irradiation with active energy rays tends to be too high.

Examples of functional group-containing monomers (a2) include hydroxyl group-containing monomers, 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. can be mentioned. These functional group-containing monomers can be used alone or in combination of two or more.

The hydroxyl group-containing monomer is preferably a hydroxyl group-containing (meth)acrylate monomer, and specific examples include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 5-hydroxypentyl. (Meth)acrylate, 6-hydroxyhexyl (meth)acrylate, (meth)acrylic acid hydroxyalkyl esters such as 8-hydroxyoctyl (meth)acrylate, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth)acrylate, diethylene glycol (Meth) acrylate, oxyalkylene-modified monomers such as polyethylene glycol (meth) acrylate, primary hydroxyl group-containing monomers such as 2-acryloyloxyethyl-2-hydroxyethyl phthalic acid; 2-hydroxypropyl (meth) acrylate, 2- secondary hydroxyl group-containing monomers such as hydroxybutyl (meth)acrylate and 3-chloro-2-hydroxypropyl (meth)acrylate; tertiary hydroxyl group-containing monomers such as 2,2-dimethyl 2-hydroxyethyl (meth)acrylate; be able to.
Among the above hydroxyl group-containing monomers, primary hydroxyl group-containing monomers are preferred in terms of excellent reactivity with the cross-linking agent (D) described later, particularly 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) Acrylates are preferred.

The content of the hydroxyl group-containing monomer in the polymerization components is usually 0.1 to 20% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight. If the content is too high, cross-linking will proceed before the drying step, tending to cause problems in coatability. tend to become

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. , cinnamic acid and the like. Among them, (meth)acrylic acid is preferably used in terms of copolymerizability.

The content of the carboxy group-containing monomer in the polymerization component is usually 10% by weight or less, preferably 5% by weight or less, more preferably 1% by weight or less, and particularly preferably 0.3% by weight or less. If the content is too large, there is a tendency that the material to be processed is likely to deteriorate, and cross-linking proceeds before the drying process, which tends to cause problems in coatability.

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

The content of the amino group-containing monomer in the polymerization component is usually 30% by weight or less, preferably 10% by weight or less, and more preferably 5% by weight or less. If the content is too high, cross-linking proceeds before the drying process, which tends to cause problems in coatability.

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

The content of the amide group-containing monomer in the polymerization component is usually 30% by weight or less, preferably 10% by weight or less, and more preferably 5% by weight or less. If the content is too high, cross-linking proceeds before the drying process, which tends to cause problems in coatability.

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

The content of the glycidyl group-containing monomer in the polymerization component is usually 1% by weight or less, preferably 0.5% by weight or less, and more preferably 0.3% by weight or less. If the content is too high, cross-linking proceeds before the drying process, which tends to cause problems in coatability.

Examples of the above sulfonic acid group-containing monomers include olefin sulfonic acids such as ethylenesulfonic acid, allylsulfonic acid and methallylsulfonic acid, 2-acrylamido-2-methylolpropanesulfonic acid, styrenesulfonic acid and salts thereof. .

The content of the sulfonic acid group-containing monomer in the polymerization component is usually 1% by weight or less, preferably 0.5% by weight or less, and more preferably 0.3% by weight or less. If the content is too high, cross-linking proceeds before the drying process, which tends to cause problems in coatability.

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

The content of the acetoacetyl group-containing monomer in the polymerization component is usually 10% by weight or less, preferably 5% by weight or less, and more preferably 1% by weight or less. If the content is too high, cross-linking proceeds before the drying process, which tends to cause problems in coatability.

Examples of other copolymerizable monomers (a3) include carboxylic acid vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl stearate, and 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; Biphenyloxy structure-containing (meth) acrylic acid ester monomer; 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) ) Monomers containing alkoxy or oxyalkylene groups such as acrylates and polypropylene glycol mono(meth)acrylate; acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, dialkyl itaconate Ester, dialkyl fumarate, allyl alcohol, acryl chloride, methyl vinyl ketone, allyl trimethyl ammonium chloride, dimethyl allyl vinyl ketone and the like. These may be used independently and may use 2 or more types together.

The content of the above-mentioned other copolymerizable monomer (a3) in the polymerization component is usually 40% by weight or less, preferably 30% by weight or less, more preferably 25% by weight or less. If the amount of the other copolymerizable monomer (a3) is too large, the adhesive properties tend to deteriorate.

The acrylic resin (A) used in the present invention is such that the glass transition temperature is −10° C. or lower, the (meth)acrylic acid alkyl ester monomer (a1), the functional group-containing monomer (a2), and if necessary It can be obtained by appropriately selecting and polymerizing other copolymerizable monomers (a3). As such a polymerization method, conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like can be suitably used. Among them, production by solution radical polymerization is preferable in that the acrylic resin (A) can be produced safely and stably with any monomer composition.

In the solution radical polymerization, for example, in an organic solvent, a (meth) acrylic acid alkyl ester monomer (a1), a functional group-containing monomer (a2), and optionally other copolymerizable monomers (a3), etc. A monomer component and a polymerization initiator may be mixed or added dropwise, and polymerized at reflux 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. and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone.

As the polymerization initiator, a usual radical polymerization initiator can be used. Peroxide-based polymerization initiators such as oxide, di-tert-butyl peroxide, cumene hydroperoxide, and the like are included.

The glass transition temperature (Tg) of the acrylic resin (A) obtained by the above polymerization method must be −10° C. or lower from the viewpoint of excellent peelability after heating and irradiation with active energy rays. It is preferably -70 to -15°C, particularly preferably -60 to -20°C, more preferably -50 to -25°C, and most preferably -40 to -30°C. If the glass transition temperature is too high, the releasability is lowered when active energy rays are applied after the heating step. In addition, if the glass transition temperature is too low, there is a tendency that the contamination of the workpiece increases.

In the present invention, the glass transition temperature (Tg) of the acrylic resin (A) is a value measured using a differential scanning calorimeter "DSC Q2000" manufactured by TA Instruments. The measurement temperature range is -80 to 40°C, and the temperature rise rate is 5°C/min.

The weight average molecular weight of the acrylic resin (A) is generally 100,000 to 2,000,000, preferably 150,000 to 1,500,000, particularly preferably 200,000 to 1,200,000, and particularly preferably 300,000 to 1,000,000. . If the weight-average molecular weight is too small, it tends to contaminate a member to be processed.

Furthermore, the degree of dispersion (weight average molecular weight/number average molecular weight) of the acrylic resin (A) is preferably 20 or less, particularly preferably 10 or less, more preferably 7 or less, and particularly preferably 5 or less. preferable. If the degree of dispersion is too high, there is a tendency to increase the contamination of the workpiece. In addition, the lower limit of the degree of dispersion is usually 1.1 in view of manufacturing limitations.

The above weight average molecular weight is the weight average molecular weight in terms of standard polystyrene molecular weight. GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , number of theoretical plates: 10,000 plates/line, filler material: styrene-divinylbenzene copolymer, filler particle size : 10 μm) in series, and the number average molecular weight can be obtained in the same manner.

[Urethane (meth)acrylate compound (B)]
The urethane (meth)acrylate compound (B) used in the present invention is a compound having a urethane bond and a (meth)acryloyl group.

The urethane (meth)acrylate compound (B) is a urethane (meth)acrylate compound (B1) which is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1) and a polyvalent isocyanate compound (b2). It may be a urethane (meth)acrylate compound (B2) that is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1), a polyvalent isocyanate compound (b2) and a polyol compound (b3). may Among them, in the present invention, it is preferable to use the urethane (meth)acrylate compound (B1) in terms of releasability after irradiation with active energy rays.
In the present invention, the urethane (meth)acrylate compound (B) may be used alone or in combination of two or more.

The hydroxyl group-containing (meth)acrylate compound (b1) preferably has one hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Hydroxyalkyl (meth)acrylates such as acrylates, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethyl acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate , caprolactone-modified 2-hydroxyethyl (meth) acrylate, dipropylene glycol (meth) acrylate, fatty acid-modified glycidyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxy-3 -Hydroxyl group-containing (meth)acrylate compounds containing one ethylenically unsaturated group such as (meth)acryloyloxypropyl (meth)acrylate; glycerin di(meth)acrylate, 2-hydroxy-3-acryloyl-oxypropyl Hydroxyl group-containing (meth)acrylate compounds containing two ethylenically unsaturated groups such as methacrylate; pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate , dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, etc. Examples include acrylate compounds.
The hydroxyl group-containing (meth)acrylate compounds (b1) can be used alone or in combination of two or more.

Among these, the hydroxyl group-containing (meth)acrylate compound (b1) containing 3 or more ethylenically unsaturated groups is preferable from the viewpoint of excellent curability after irradiation with active energy rays, and pentaerythritol tri(meth)acrylate and dipentaerythritol penta(meth)acrylate are particularly preferred.

Examples of polyvalent isocyanate compounds (b2) include aromatic compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate. Polyvalent isocyanates; aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate and lysine triisocyanate; system polyvalent isocyanates; or isocyanurates or polymeric compounds of these polyvalent isocyanates, allophanate-type polyisocyanates, buret-type polyisocyanates, water-dispersed polyisocyanates (e.g., Nippon Polyurethane Industry Co., Ltd. "Aquanate 100", " Aquanate 110", "Aquanate 200", "Aquanate 210", etc.). These can be used alone or in combination of two or more.

Among them, aromatic polyvalent isocyanates such as tolylene diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated Alicyclic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate and norbornene diisocyanate are preferred, with lylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate and hexamethylene diisocyanate being more preferred. is rylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate.

The polyol-based compound (b3) may be any compound containing two or more hydroxyl groups. Examples include polybutadiene-based polyols, polyisoprene-based polyols, (meth)acrylic-based polyols, and polysiloxane-based polyols. These can be used singly or in combination of two or more.

Examples of the aliphatic polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, dimethylolpropane, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-butyl- 2-ethyl-1,3-propanediol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, 1,6 -hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, pentaerythritol diacrylate, 1,9-nonanediol, 2-methyl-1,8 - Aliphatic alcohols containing two hydroxyl groups such as octanediol, sugar alcohols such as xylitol and sorbitol, fatty alcohols containing three or more hydroxyl groups such as glycerin, trimethylolpropane, trimethylolethane, etc. is mentioned.

Examples of the alicyclic polyol include cyclohexanediols such as 1,4-cyclohexanediol and cyclohexyldimethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tricyclodecanedimethanol.

Examples of the polyether-based polyols include alkylene structure-containing polyether-based polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol, and polyhexamethylene glycol, and polyether-based polyols containing these polyalkylene glycols. Examples include random or block copolymers.

Examples of the polyester-based polyol include three types of components: a condensation polymer of a polyhydric alcohol and a polycarboxylic acid; a ring-opening polymer of a cyclic ester (lactone); a polyhydric alcohol, a polycarboxylic acid, and a cyclic ester. and the like.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-tri methylenediol, 1,5-pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, glycerin , trimethylolpropane, trimethylolethane, cyclohexanediols (1,4-cyclohexanediol, etc.), bisphenols (bisphenol A, etc.), sugar alcohols (xylitol, sorbitol, etc.), and the like.
Examples of polyvalent carboxylic acids include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; -alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid and trimellitic acid.
Examples of the cyclic ester include propiolactone, β-methyl-δ-valerolactone, ε-caprolactone and the like.

Examples of the polycarbonate-based polyols include reaction products of polyhydric alcohols and phosgene; ring-opening polymers of cyclic carbonates (alkylene carbonates and the like);
Examples of the polyhydric alcohol include the polyhydric alcohols exemplified in the description of the polyester-based polyol, and examples of the alkylene carbonate include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate. be done.
The polycarbonate-based polyol may be a compound having a carbonate bond in the molecule and a hydroxyl group at the terminal, and may have an ester bond as well as the carbonate bond.

Examples of the above-mentioned polyolefin-based polyols include those having a homopolymer or copolymer of ethylene, propylene, butene, etc. as a saturated hydrocarbon skeleton and hydroxyl groups at the molecular terminals thereof.

Examples of the polybutadiene-based polyols include those having a butadiene copolymer as a hydrocarbon skeleton and hydroxyl groups at the ends of the molecules.
The polybutadiene-based polyol may be a hydrogenated polybutadiene polyol in which all or part of the ethylenically unsaturated groups contained in its structure are hydrogenated.

Examples of the polyisoprene-based polyols include those having an isoprene copolymer as a hydrocarbon skeleton and hydroxyl groups at the molecular terminals thereof.
The polyisoprene-based polyol may be a hydrogenated polyisoprene polyol in which all or part of the ethylenically unsaturated groups contained in its structure are hydrogenated.

Examples of the (meth)acrylic polyol include those having at least two hydroxy groups in the molecule of a (meth)acrylic acid ester polymer or copolymer. are, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, (meth)acrylic (Meth)acrylic acid alkyl esters such as 2-ethylhexyl acid, decyl (meth)acrylate, dodecyl (meth)acrylate and octadecyl (meth)acrylate.

Examples of the polysiloxane-based polyol include dimethylpolysiloxane polyol and methylphenylpolysiloxane polyol.

Among these, aliphatic polyols and alicyclic polyols are preferably used, and polyester polyols, polyether polyols and polycarbonate polyols are preferably used in terms of versatility.

The weight average molecular weight of the polyol-based compound (b3) is preferably 60 to 5,000, particularly preferably 100 to 3,000, further preferably 150 to 2,000. If the weight-average molecular weight of the polyol-based compound (b3) is too large, the resulting urethane (meth)acrylate-based compound (B2) and the acrylic resin (A) will be difficult to mix uniformly, leaving adhesive residue on the workpiece. tend to occur more easily. On the other hand, if the weight average molecular weight of the polyol compound (b3) is too small, the pressure-sensitive adhesive layer tends to crack easily after irradiation with active energy rays.

The urethane (meth)acrylate compound (B) can be produced by reacting the components as described above by known reaction means.
Usually, in the case of the urethane (meth)acrylate compound (B1), the hydroxyl group-containing (meth)acrylate compound (b1) and the polyvalent isocyanate compound (b2) are combined with the urethane (meth)acrylate compound (B2 ), the polyol compound (b3) can be further charged into a reactor all at once or separately and subjected to a urethanization reaction by a known reaction means. Further, in the case of producing the urethane (meth)acrylate compound (B2), the reaction product obtained by pre-reacting the polyol compound (b3) and the polyvalent isocyanate compound (b2) contains a hydroxyl group-containing ( The method of reacting the meth)acrylate compound (b1) is useful in terms of stability of the urethanization reaction, reduction of by-products, and the like.

In the reaction between the hydroxyl group-containing (meth)acrylate compound (b1) and the polyvalent isocyanate compound (b2), it is preferable to use a reaction catalyst for the purpose of promoting the reaction. As such a reaction catalyst, a bismuth compound (C) is preferred. When the urethane (meth)acrylate compound (B) is produced by reacting the hydroxyl group-containing (meth)acrylate compound (b1) and the polyvalent isocyanate compound (b2) using the bismuth compound (C), Since the bismuth-based compound (C) remains in the urethane (meth)acrylate-based compound (B), it is possible to efficiently include the bismuth-based compound (C) in the active energy ray-curable peelable pressure-sensitive adhesive composition. can.

Examples of the bismuth-based compound (C) include bismuth nitrate, bismuth bromide, bismuth iodide, bismuth sulfide, organic bismuth compounds such as dibutylbismuth dilaurate and dioctylbismuth dilaurate, and bismuth 2-ethylhexanoate. , bismuth naphthenate, bismuth isodecanoate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth bismuth neodecano bismuth salts of organic acids such as bismuth salts, bismuth disalicylate salts, bismuth digallate salts, and the like. These can be used alone or in combination of two or more. Among them, from the viewpoint of reaction efficiency, organic acid bismuth salts are preferable, and 2-ethylhexanoate bismuth salts are more preferable.

When the bismuth-based compound (C) is used as a reaction catalyst, the amount used is 100 parts by weight in total of the hydroxyl group-containing (meth)acrylate-based compound (b1) and the polyvalent isocyanate-based compound (b2), in terms of bismuth element. It is usually 1×10 ^-5 to 1 part by weight, preferably 1×10 ^-4 to 0.5 part by weight, more preferably 1×10 ^-3 to 0.1 part by weight. If the amount of the bismuth-based compound (C) used is too small, the production of the urethane (meth)acrylate-based compound (B) tends to take a long time, and if the amount used is too large, the adherend stain resistance tends to decrease. There is

In the present invention, "bismuth element conversion" means that the bismuth-based compound (C) is converted as the bismuth element possessed by the bismuth-based compound (C). Specifically, ICP-MS (manufactured by Agilent Technologies , 7500ce type; standard addition method).

In the reaction between the hydroxyl group-containing (meth)acrylate compound (b1) and the polyvalent isocyanate compound (b2), the use of the bismuth compound (C) can increase the adhesive strength before irradiation with active energy rays. However, a catalyst other than the bismuth-based compound (C) may be used, or the bismuth-based compound (C) and a catalyst other than the bismuth-based compound (C) may be used in combination.

Examples of catalysts other than the bismuth-based compound (C) include organometallic compounds such as dibutyltin dilaurate, trimethyltin hydroxide, tetra-n-butyltin, zinc octoate, tin octoate, tin octoate, and naphthenic acid. Metal salts such as cobalt, stannous chloride, stannic chloride, triethylamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N ,N,N',N'-tetramethyl-1,3-butanediamine, amine catalysts such as N-ethylmorpholine, inorganic zirconium, organic zirconium, zirconium catalysts such as simple zirconium, zinc 2-ethylhexanoate/ A combination of two or more catalysts such as zirconium tetraacetylacetonate can be mentioned. These catalysts can be used singly or in combination of two or more.

As a catalyst other than the bismuth-based compound (C), a tin-free catalyst is preferable, and even when a tin-containing catalyst is used, the amount used is a hydroxyl group-containing (meth)acrylate compound It is preferably 1×10 ⁻³ parts by weight or less in terms of tin element with respect to a total of 100 parts by weight of (b1) and polyvalent isocyanate compound (b2). The amount of tin in terms of element can also be obtained by measuring the tin-containing catalyst by ICP-MS, as in the case of the bismuth-based compound (C).

In the above urethanization reaction, an organic solvent having no functional group that reacts with an isocyanate group, for example, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatics such as toluene and xylene. Organic solvents, such as organic solvents, can be used.

The reaction temperature is generally 30 to 90°C, preferably 40 to 80°C, and the reaction time is generally 2 to 10 hours, preferably 3 to 8 hours.

The urethane (meth)acrylate compound (B) is obtained by terminating the above urethanization reaction when the residual isocyanate group content in the reaction system becomes 0.3% by weight or less.

The urethane (meth)acrylate compound (B) obtained in this manner is obtained by using the bismuth compound (C) as a reaction catalyst to obtain the bismuth compound (C) in the urethane (meth)acrylate compound (B). can be contained.

The urethane (meth)acrylate compound (B) preferably contains 4 or more ethylenically unsaturated groups, more preferably 4 to 20 groups, and particularly preferably 5 to 18, particularly preferably 6 to 15.
If the number of such ethylenically unsaturated groups is too large, the crosslink density after irradiation with active energy rays becomes too large, and cracks tend to occur in the pressure-sensitive adhesive layer. , tends to be difficult to peel off after irradiation with active energy rays.

The weight average molecular weight of the urethane (meth)acrylate compound (B) is usually 500-10,000, preferably 750-5,000, more preferably 1,000-4,000. If the weight-average molecular weight is too large, the viscosity of the urethane (meth)acrylate compound (B) increases, the compatibility with the acrylic resin (A) decreases, and adhesive residue tends to easily occur on the workpiece. There is If the weight-average molecular weight is too small, the urethane (meth)acrylate compound (B) tends to bleed out from the peelable pressure-sensitive adhesive sheet, tending to leave an adhesive residue.

The above weight-average molecular weight is the weight-average molecular weight in terms of standard polystyrene molecular weight. 200 x 1 and 4 ACQUITY APC XT 45 x 2 are used in series for measurement.

The urethane (meth)acrylate compound (B) used in the present invention preferably has a viscosity at 60° C. of 500 to 100,000 mPa·s, particularly preferably 1,000 to 50,000 mPa·s. If the viscosity is outside the above range, the coatability tends to deteriorate. The viscosity can be measured with an E-type viscometer.

The content of the urethane (meth)acrylate compound (B) in the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention is usually 1 to 100 parts by weight with respect to 100 parts by weight of the acrylic resin (A). is preferably 10 to 80 parts by weight, more preferably 15 to 70 parts by weight, and most preferably 20 to 65 parts by weight. If the content of the urethane (meth)acrylate compound (B) is too small, the peelability after irradiation with active energy rays tends to be reduced, and if it is too large, the adhesive will be plasticized, resulting in adhesion before irradiation with active energy rays. There is a tendency that the adhesive layer tends to crack after irradiation with active energy rays, as well as a decrease in strength and adhesive residue.

[Bismuth-based compound (C)]
Since the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention contains a specific trace amount of the bismuth-based compound (C), it exhibits an effect of being excellent in adhesive strength before being irradiated with an active energy ray.

As the bismuth-based compound (C), a known general compound can be used. Specifically, the same compounds as listed in the reaction catalyst for the urethane (meth)acrylate-based compound (B) described above are used. be able to. Moreover, the bismuth-based compound (C) may be used alone or in combination of two or more.

When the bismuth compound (C) remains in the urethane (meth)acrylate compound (B) and its content is within the following range, the bismuth compound (C) is usually newly activated. A bismuth-based compound (C) may be further blended as long as the content is within the following range, although it is not necessary to blend it in the energy ray-curable peelable pressure-sensitive adhesive composition. In this case, the bismuth-based compound (C) blended in the active energy ray-curable peelable pressure-sensitive adhesive composition is the same compound as the bismuth-based compound (C) used in the production of the urethane (meth)acrylate compound (B). is preferably used, but different compounds may be used.

The content of the bismuth compound (C) in the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention is usually 1×10 in terms of bismuth element with respect to 100 parts by weight of the acrylic resin (A). ⁻⁵ to 1 part by weight, preferably 5×10 ⁻⁵ to 1×10 ⁻¹ part by weight, particularly preferably 1×10 ⁻⁴ to 1×10 ⁻² part by weight. If the content of the bismuth-based compound (C) is too low, the adhesive strength before irradiation with active energy rays tends to decrease. tend to decline.

In addition, the content of the bismuth-based compound (C) in the active energy ray-curable peelable pressure-sensitive adhesive composition is usually It is 1×10 ⁻⁵ to 1 part by weight, preferably 1×10 ⁻⁴ to 0.5 part by weight, particularly preferably 1×10 ⁻³ to 0.1 part by weight. If the content of the bismuth-based compound (C) is too low, the adhesive strength before irradiation with active energy rays tends to decrease. tend to decline.

[Crosslinking agent (D)]
In the present invention, it is preferable to incorporate a cross-linking agent (D), since it forms a cross-linked structure with the acrylic resin (A) and provides excellent adhesive strength before irradiation with active energy rays. Examples of the cross-linking agent (D) include isocyanate cross-linking agents, epoxy cross-linking agents, aziridine cross-linking agents, oxazoline cross-linking agents, melamine cross-linking agents, aldehyde cross-linking agents, and amine cross-linking agents. Among these, it is preferable to use an isocyanate-based cross-linking agent from the viewpoint of improving the adhesiveness of the peelable pressure-sensitive adhesive sheet to the base sheet and the reactivity with the acrylic resin (A).
Moreover, these crosslinking agents (D) may be used alone or in combination of two or more.

Examples of the isocyanate-based crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, and diphenylmethane-4,4-diisocyanate. , isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and polyol compounds such as these polyisocyanate compounds and trimethylolpropane adducts of these polyisocyanate compounds, burettes and isocyanurates of these polyisocyanate compounds, and the like.
Among these, isocyanurate form of hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,4-tolylene diisocyanate, or 2,6-tolylene diisocyanate and trimethylol are used in terms of chemical resistance and reactivity with functional groups. Adducts with propane, isocyanurates of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, and adducts of tetramethylxylylene diisocyanate and trimethylolpropane are preferred.

Examples of the epoxy-based cross-linking agent include bisphenol A/epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether. , trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidylerythritol, diglycerol polyglycidyl ether, 1,3′-bis(N,N-diglycidylaminomethyl)cyclohexane, N , N,N',N'-tetraglycidyl-m-xylenediamine and the like.

Examples of the aziridine-based cross-linking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4 '-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide) and the like.

Examples of the oxazoline-based cross-linking agent include 2,2′-bis(2-oxazoline), 1,2-bis(2-oxazoline-2-yl)ethane, 1,4-bis(2-oxazoline-2- yl)butane, 1,8-bis(2-oxazolin-2-yl)butane, 1,4-bis(2-oxazolin-2-yl)cyclohexane, 1,2-bis(2-oxazolin-2-yl) Bisoxazoline compounds containing aliphatic or aromatic compounds such as benzene, 1,3-bis(2-oxazoline-2-yl)benzene, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, Addition polymerization of 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, etc. and polymers of one or more of oxazolines.

Examples of the melamine-based cross-linking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resins.

Examples of the aldehyde cross-linking agent include glyoxal, malondialdehyde, succindialdehyde, maleinedialdehyde, glutaredialdehyde, formaldehyde, acetaldehyde, and benzaldehyde.

Examples of the amine cross-linking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resins, and polyamides.

The content of the cross-linking agent (D) is usually 0.01 to 20 parts by weight with respect to a total of 100 parts by weight of the acrylic resin (A) and the urethane (meth)acrylate compound (B). It is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 1 part by weight. If the amount of the cross-linking agent (D) is too small, the cohesive strength of the pressure-sensitive adhesive tends to decrease, causing adhesive residue. tend to occur.

[Photoinitiator (E)]
In addition, it is preferable to blend a photopolymerization initiator (E) into the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention, since the peelability after irradiation with an active energy ray is excellent. The photopolymerization initiator (E) may be one that generates radicals by the action of light. Examples include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl Ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenylketone, 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)phenyl]-1-butanone, 2-hydroxy-2-methyl-1-[4-( Acetophenones such as 1-methylvinyl)phenyl]propanone oligomer; Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; Benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone , 4-benzoyl-4′-methyl-diphenylsulfide, 3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N -Dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide, (4-benzoylbenzyl)trimethylammonium chloride and other benzophenones; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one meso Thioxanthones such as chloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethyl benzoyl)-phenylphosphine oxide; and the like. Among them, acetophenones, especially 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, thioxanthones, Especially 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.
In addition, these photoinitiators (E) can be used individually or can use 2 or more types together.

The content of the photopolymerization initiator (E) is 0.01 to 10 parts by weight with respect to a total of 100 parts by weight of the acrylic resin (A) and the urethane (meth)acrylate compound (B). is preferred, particularly preferably 0.1 to 5 parts by weight, particularly preferably 0.5 to 2 parts by weight.
If the content of the photopolymerization initiator (E) is too low, the curability by active energy ray irradiation tends to be low, and the peelability after active energy ray irradiation tends to be low. tend to increase.

Further, as auxiliary agents for these photopolymerization initiators (E), for example, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethyl Benzoic acid, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone , 2,4-diisopropylthioxanthone and the like can also be used in combination. These auxiliaries can also be used alone or in combination of two or more.

[Other ingredients]
The active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention preferably contains, for example, an ethylenically unsaturated compound within a range that does not impair the effects of the present invention, from the standpoint of releasability after irradiation with an active energy ray. In addition, it may further contain additives such as antistatic agents, antioxidants, plasticizers, fillers, pigments, diluents, anti-aging agents, UV absorbers, UV stabilizers, and tackifying resins. These additives can be used singly or in combination of two or more. Antioxidants are particularly effective in maintaining the stability of the pressure-sensitive adhesive layer. The content of the antioxidant when blended is not particularly limited, but is preferably 0.01 to 5% by weight. In addition to the additives, a small amount of impurities and the like contained in the raw materials for manufacturing the constituent components of the active energy ray-curable peelable pressure-sensitive adhesive composition may be contained.

The active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention preferably does not contain tin in the composition. It is preferably 1×10 ⁻³ wt % or less in terms of tin element in the removable pressure-sensitive adhesive composition. In addition, the above-mentioned "tin" is meant to include tin alone and tin compounds.

Thus, an acrylic resin (A) having a glass transition temperature of −10° C. or lower, a urethane (meth)acrylate compound (B) and a specific trace amount of a bismuth compound (C), preferably a cross-linking agent (D), photopolymerizable By mixing the initiator (E) and, if necessary, other components, the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention can be obtained.

The active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention is crosslinked by the above-mentioned crosslinking agent (D) and exhibits performance as a pressure-sensitive adhesive. ) The acrylate compound (B) is polymerized to cure the pressure-sensitive adhesive, resulting in a reduction in the pressure-sensitive adhesive strength, thereby exhibiting the releasability.

The pressure-sensitive adhesive obtained by cross-linking the active energy ray-curable peelable pressure-sensitive adhesive composition is usually used temporarily when processing workpieces such as electronic substrates, semiconductor wafers, glass processed products, metal plates, and plastic plates. It is preferably used as a pressure-sensitive adhesive layer of a peelable pressure-sensitive adhesive sheet for surface protection. In addition, since the peelable pressure-sensitive adhesive sheet of the present invention is excellent in heat resistance, even when it is heated after being attached to the surface of the member to be processed, excellent peelability can be obtained by irradiating the active energy ray. demonstrate.
The peelable pressure-sensitive adhesive sheet will be described below.

The peelable pressure-sensitive adhesive sheet usually has a base sheet, a pressure-sensitive adhesive layer in which the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention is crosslinked, and, if necessary, a release film. As a method for producing such a peelable pressure-sensitive adhesive sheet, first, the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention is used as it is, or the concentration is adjusted with an appropriate organic solvent, and then applied on a release film or a base sheet. Apply directly. Thereafter, it is dried by heat treatment at 80 to 120° C. for 0.5 to 10 minutes, etc., and is attached to a base sheet or a release film to obtain a peelable pressure-sensitive adhesive sheet. Moreover, in order to balance adhesive physical properties, aging may be further performed after drying.

Examples of the base sheet include polyester-based resins such as polyethylene naphtate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate/isophthalate copolymer; polyolefin-based resins such as polyethylene, polypropylene, and polymethylpentene; and polyvinyl fluoride. , polyvinylidene fluoride, polyethylene fluoride resins such as polyethylene fluoride; polyamides such as nylon 6, 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; cellulose resins such as cellulose triacetate and cellophane; acrylics such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate and polybutyl acrylate Resin; polystyrene; polycarbonate; polyarylate; synthetic resin sheets such as polyimide; metal foils of aluminum, copper and iron; be done. These base sheets can be used as a single-layer body or as a multi-layer body in which two or more types are laminated. Among these, a synthetic resin sheet is preferable from the viewpoint of weight reduction.

Furthermore, as the release film, for example, release-treated various synthetic resin sheets, paper, woven fabrics, non-woven fabrics, etc. exemplified in the base sheet can be used.

In addition, the method for applying the active energy ray-curable peelable pressure-sensitive adhesive composition is not particularly limited as long as it is a general coating method, and examples thereof include roll coating, die coating, gravure coating, and comma coating. , screen printing, and the like.

The thickness of the pressure-sensitive adhesive layer of the peelable pressure-sensitive adhesive sheet is generally preferably 1 to 200 μm, more preferably 5 to 100 μm.

As the aging conditions, the temperature is usually room temperature (23° C.) to 70° C., and the time is usually 1 to 30 days. It may be carried out under conditions such as 10 days, 40° C. for 1 to 7 days, and the like.

Thus, the peelable pressure-sensitive adhesive sheet of the present invention is obtained. In the peelable pressure-sensitive adhesive sheet, the content of the bismuth-based compound (C) in the pressure-sensitive adhesive layer of the peelable pressure-sensitive adhesive sheet is usually 1×10 ^-6 to 1% by weight, preferably 1×, in terms of bismuth element. 10 ⁻⁵ to 1×10 ⁻¹ wt %, particularly preferably 1×10 ⁻⁴ to 1×10 ⁻² wt %. If the content of the bismuth-based compound (C) is too low, the adhesive strength before irradiation with active energy rays tends to decrease. tend to decline.

As described above, the adhesive strength of the peelable pressure-sensitive adhesive sheet of the present invention is reduced by irradiation with active energy rays. In addition to light rays such as infrared rays, electromagnetic waves such as X-rays and γ-rays, electron beams, proton beams, neutron beams and the like can be used. Among them, ultraviolet light is preferable in terms of curing speed, availability of irradiation equipment, price, and the like.

The cumulative dose of ultraviolet rays 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 adhesive layer, the thickness of the adhesive layer, and other conditions.

The adhesive strength of the peelable pressure-sensitive adhesive sheet varies depending on the type of base sheet, the type of member to be processed, etc., but is preferably 4.0 N/25 mm or more, and further 6.0 N/25 mm before irradiation with active energy rays. 8.0 N/25 mm or more is particularly preferable.

Moreover, the adhesive strength after irradiation with active energy rays is preferably 0.8 N/25 mm or less, more preferably 0.5 N/25 mm or less, and particularly preferably 0.3 N/25 mm or less.

Further, the peelable pressure-sensitive adhesive sheet of the present invention is heated at 150° C. for 1 hour and then irradiated with ultraviolet rays (accumulated irradiation amount: 250 mJ/cm ² ). It is preferably 0.5 N/25 mm or less, and particularly preferably 0.3 N/25 mm or less.

According to the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention, for example, a peelable pressure-sensitive adhesive sheet using this as a pressure-sensitive adhesive layer is laminated to a member to be processed, and the surface of the member to be processed is temporarily After protection, by irradiating active energy rays as necessary, the pressure-sensitive adhesive layer is cured, the adhesive strength is lowered, and it can be easily peeled off from the member to be processed. Furthermore, since the peelable pressure-sensitive adhesive sheet of the present invention is excellent in heat resistance, even if it is heated after being attached to the surface of the member to be processed, by irradiating the active energy ray thereafter, It exhibits excellent releasability.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In addition, "%" and "parts" hereinafter mean weight standards.

<Preparation of acrylic resin (A) solution>
[Acrylic resin (A-1)]
In a reactor equipped with a temperature controller, a thermometer, a stirrer, a dropping funnel and a reflux condenser, 90 parts of ethyl acetate, 1.25 parts of methyl ethyl ketone, and 0.025 of azobisisobutyronitrile (AIBN) as a polymerization catalyst. parts were charged, the temperature was raised while stirring, and when the internal temperature was stabilized at 78° C., 77 parts of n-butyl acrylate, 20 parts of methyl acrylate, 3 parts of 2-hydroxyethyl acrylate, and 0.038 parts of AIBN were used as copolymer components. was added dropwise over 2 hours and reacted under reflux. Then, 3 hours after the start of the reaction, a solution in which 3.8 parts of ethyl acetate and 0.038 parts of AIBN were dissolved was added, and 5 hours after the start of the reaction, 3.8 parts of ethyl acetate and 2,2'-azobis(2, 4-Dimethylvaleronitrile) (ADVN) 0.025 parts of the solution is added, and after 7 hours from the start of the reaction, 46.3 parts of ethyl acetate is added to terminate the reaction, and acrylic resin (A-1). A solution [weight average molecular weight 680,000, dispersion degree 4.5, glass transition temperature -31.6°C, resin content 39.9%, viscosity 6,900 mPa·s (25°C)] was obtained.

[Acrylic resin (A'-1)]
105 parts of ethyl acetate, 6.25 parts of methyl ethyl ketone, and 0.025 of azobisisobutyronitrile (AIBN) as a polymerization catalyst were placed in a reactor equipped with a temperature controller, thermometer, stirrer, dropping funnel and reflux condenser. 37 parts of n-butyl acrylate, 60 parts of methyl acrylate, 3 parts of 2-hydroxyethyl acrylate, and 0.038 parts of AIBN as copolymer components when the internal temperature is stabilized at 78°C. was added dropwise over 2 hours and reacted under reflux. Then, 3 hours after the start of the reaction, a solution in which 3.8 parts of ethyl acetate and 0.038 parts of AIBN were dissolved was added, and 5 hours after the start of the reaction, 3.8 parts of ethyl acetate and 2,2'-azobis(2, 4-Dimethylvaleronitrile) (ADVN) 0.025 parts of a solution was added, and after 7 hours from the start of the reaction, 62.0 parts of ethyl acetate was added to terminate the reaction, and the acrylic resin (A'-1 ) solution [weight average molecular weight 590,000, dispersion degree 4.3, glass transition temperature -8.4°C, resin content 34.1%, viscosity 6,700 mPa·s (25°C)] was obtained.

A urethane (meth)acrylic compound (B) was prepared as follows.

<Preparation of urethane (meth)acrylate compound (B)>
[Urethane acrylate (B-1)]
6.6 parts of isophorone diisocyanate, a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (hydroxyl value 48 mg KOH / g) 93.4 parts, 0.06 parts of 2,6-di-tert-butyl cresol as a polymerization inhibitor, 2-ethylhexanoic acid bismuth salt (manufactured by Nitto Kasei Co., Ltd.) which is a bismuth compound (C) as a reaction catalyst ) was charged and reacted at 60° C., and the reaction was terminated when the residual isocyanate groups became 0.3% or less. Urethane acrylate (B-1) (10 ethylenically unsaturated groups, weight A mixture with an average molecular weight of 2,000) was obtained.

[Urethane acrylate (B'-1)]
6.6 parts of isophorone diisocyanate, a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (hydroxyl value 48 mg KOH / g) 93.4 parts, 0.06 parts of 2,6-di-tert-butyl cresol as a polymerization inhibitor, and 0.02 parts of dibutyltin dilaurate as a reaction catalyst were charged and reacted at 60 ° C., and the residual isocyanate group was The reaction was terminated when the content reached 0.3% or less to obtain a mixture of urethane acrylate (B'-1) (10 ethylenically unsaturated groups, weight average molecular weight of 2,000).

Moreover, each compounding component shown below was prepared.

[Metal catalyst]
- Metal catalyst (C'-1): dibutyltin dilaurate (DBTL)

[Crosslinking agent (D)]
・ Isocyanate-based cross-linking agent (D-1): Coronate HX (manufactured by Tosoh Corporation)

[Photoinitiator (E)]
- Photopolymerization initiator (E-1): bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (manufactured by IGM Resins: OMNIRAD819)

<Example 1>
[Preparation of adhesive composition]
The resin content of the acrylic resin (A-1) solution obtained above was adjusted to 40%, and 250 parts of this resin solution (100 parts of resin content), 50 parts of urethane acrylate (B-1), a cross-linking agent (D -1) 0.75 parts (0.16 equivalents with respect to the hydroxyl group of the acrylic resin (A)), 0.9 parts of the photopolymerization initiator (E-1), and toluene as a dilution solvent, and active energy A linear curable peelable pressure-sensitive adhesive composition solution (solid content: 20%) was obtained.

[Production of peelable adhesive sheet]
After coating the obtained active energy ray-curable peelable pressure-sensitive adhesive composition on an easy-adhesive polyethylene terephthalate film (thickness: 38 μm) (manufactured by Toray Industries, Inc., “T60 Lumirror”) as a base sheet with an applicator. , dried at 100 ° C. for 2 minutes, attached to a release film (manufactured by Mitsui Chemicals Tohcello, "SP-PET 38 01-BU"), and aged at 40 ° C. for 7 days to form a peelable adhesive sheet (adhesive A layer thickness of 25 μm) was obtained.
The following evaluation was performed using the obtained peelable pressure-sensitive adhesive sheet.

[Adhesive strength before active energy ray irradiation]
A test piece of 25 mm × 100 mm was prepared from the peelable pressure-sensitive adhesive sheet obtained above, and after peeling off the release film, it was placed on a stainless steel plate (SUS304BA plate) at 23 ° C. and a relative humidity of 50%. The rubber roller was reciprocated twice to apply pressure, and after standing for 30 minutes in the same atmosphere, the 180 degree peel strength (N/25 mm) was measured at a peel rate of 300 mm/min, and evaluated according to the following evaluation criteria. rice field.
(Evaluation criteria)
◎: 6.0 N/25 mm or more ○: 4.0 N/25 mm or more, less than 6.0 N/25 mm ×: less than 4.0 N/25 mm

[Adhesive strength after irradiation with active energy rays]
A test piece of 25 mm × 100 mm was prepared from the peelable pressure-sensitive adhesive sheet obtained above, and the release film was peeled off. The rubber roller was reciprocated twice to apply pressure, and after standing for 30 minutes in an atmosphere of 23 ° C. and 50% relative humidity, using one 80 W high-pressure mercury lamp, 5.1 m / from a height of 18 cm. Ultraviolet irradiation (accumulated irradiation amount: 180 mJ/cm ² ) was performed at a conveyor speed of min. Further, after standing for 30 minutes in an atmosphere of 23° C. and 50% relative humidity, the 180 degree peel strength (N/25 mm) was measured at a peel speed of 300 mm/min, and evaluated according to the following evaluation criteria.
(Evaluation criteria)
◎: 0.5 N/25 mm or less ○: More than 0.5 N/25 mm, 0.8 N/25 mm or less ×: More than 0.8 N/25 mm

[Adhesive strength after heating/active energy ray irradiation]
A test piece of 25 mm × 100 mm was prepared from the peelable pressure-sensitive adhesive sheet obtained above, and after peeling off the release film, it was placed on a stainless steel plate (SUS304BA plate) at 23 ° C. and a relative humidity of 50%. The rubber roller was reciprocated twice to apply pressure, and then heat treatment was performed at 150° C. for 1 hour. The stainless steel plate with the heat-treated peelable pressure-sensitive adhesive sheet was allowed to stand in an atmosphere of 23° C. and 50% relative humidity for 30 minutes, and then was peeled off from a height of 18 cm using a single 80 W high-pressure mercury lamp. Ultraviolet irradiation was performed at a conveyor speed of 1 m/min (accumulated irradiation amount 180 mJ/cm ² ). Further, after standing for 30 minutes in an atmosphere of 23° C. and 50% relative humidity, the 180° peel strength (N/25 mm) was measured at a peel speed of 300 mm/min, and evaluated according to the following evaluation criteria.
(Evaluation criteria)
◎: 0.5 N/25 mm or less ○: More than 0.5 N/25 mm, 0.8 N/25 mm or less ×: More than 0.8 N/25 mm

[Stain resistance of adherend]
After peeling the peelable pressure-sensitive adhesive sheet from the stainless steel plate (SUS304BA plate) by the method described above, adhesive residue on the surface of the stainless steel plate (SUS304BA plate) was visually observed and evaluated according to the following evaluation criteria.
(Evaluation criteria)
○・・・No adhesive residue △・・・Partial adhesive residue ×・・・Full adhesive residue

<Comparative Example 1>
Example 1 was repeated except that 50 parts of the urethane acrylate compound (B'-1) was added instead of the urethane acrylate compound (B-1), and 0.0085 parts of the metal catalyst (C'-1) was added. to obtain an active energy ray-curable peelable pressure-sensitive adhesive composition, and the same evaluation as in Example 1 was performed.

<Comparative Example 2>
Active energy ray-curable peel-type adhesive in the same manner as in Example 1 except that 250 parts of acrylic resin (A'-1) (100 parts of resin content) was blended instead of acrylic resin (A-1) A composition was obtained and evaluated in the same manner as in Example 1.

<Comparative Example 3>
In Example 1, 250 parts of acrylic resin (A'-1) instead of acrylic resin (A-1) (100 parts of resin content), urethane acrylate compound instead of urethane acrylate compound (B-1) An active energy ray-curable peelable pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that 50 parts of the compound (B'-1) and 0.0085 parts of the metal catalyst (C'-1) were added. was evaluated.

The evaluation results of Examples and Comparative Examples are shown in Table 1 below.

From Table 1 above, in the examples, the adhesive strength before irradiation with active energy rays is excellent, the adhesive strength after irradiation with active energy rays is excellent, and the adhesive strength after heating and irradiation with active energy rays is also excellent. On the other hand, in Comparative Example 1 containing a tin-based compound as a metal catalyst, the adhesive strength before irradiation with active energy rays was inferior, and in Comparative Example 2 with a high glass transition temperature of the acrylic resin, heating and In Comparative Example 3, in which the adhesive strength after irradiation with active energy rays is inferior, the tin-based compound is contained as a metal catalyst, and the glass transition temperature of the acrylic resin is high, after heating and irradiation with active energy rays was inferior in adhesive strength, and in addition, the adherend staining property after heating and irradiation with active energy rays was inferior. This also shows that it is important to contain a bismuth-based compound as a metal catalyst and to contain an acrylic resin having a glass transition temperature of a predetermined temperature or lower.

The active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention can be suitably used as a temporary surface-protecting pressure-sensitive adhesive film when processing semiconductor wafers, printed circuit boards, glass processed products, metal plates, plastic plates, and the like. can be done.

Claims (5)

An active energy ray-curable peelable pressure-sensitive adhesive composition containing an acrylic resin (A), a urethane (meth)acrylate compound (B) , a bismuth compound (C) and a cross-linking agent (D) , The acrylic resin (A) has a glass transition temperature of −10° C. or lower, and the bismuth-based compound (C) was used as a catalyst during the production of the urethane (meth)acrylate-based compound (B), and , the content of the bismuth-based compound (C) is 1 × 10 ^-5 to 1 part by weight in terms of bismuth element with respect to 100 parts by weight of the acrylic resin (A) , and the cross-linking agent (D) is An active energy ray-curable peelable pressure-sensitive adhesive composition characterized by being an isocyanate cross-linking agent . 2. The active energy ray-curable peelable pressure-sensitive adhesive composition according to claim 1, further comprising a photopolymerization initiator (E). The content of the bismuth compound (C) is 1×10 ^-5 to 1 part by weight in terms of bismuth element per 100 parts by weight of the urethane (meth)acrylate compound (B). 3. The active energy ray-curable peelable pressure-sensitive adhesive composition according to Item 1 or 2 . A peelable pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer in which the active energy ray-curable peelable pressure-sensitive adhesive composition according to any one of claims 1 to 3 is crosslinked. 5. The peelable pressure-sensitive adhesive sheet according to claim 4, wherein the content of the bismuth-based compound (C) in the pressure-sensitive adhesive layer is 1×10 ⁻⁶ to 1% by weight in terms of bismuth element.