CN112996875B - Adhesive composition and surface protective film - Google Patents

Abstract

The invention aims to provide an adhesive with good pollution of an adherend after peeling. The adhesive composition of the present invention comprises a urethane resin (A) having a hydroxyl group and a curing agent (B), wherein the urethane resin (A) is a reaction product of a polyol (a 1) and a polyisocyanate (a 2), and the polyisocyanate (a 2) comprises a polyisocyanate (a 2-2) having 3 or more isocyanate groups.

Description

Adhesive composition and surface protective film

Technical Field

The present invention relates to an adhesive composition and a surface protective film.

Background

For the purpose of preventing surface contamination and damage of various substrates, a surface protective film is used. The surface protective film is attached to an optical member or the like in a process for manufacturing a display device, for example, and is peeled off from the optical member or the like at a stage where surface protection is not required.

As an adhesive used for such a surface protective film, an adhesive comprising a urethane prepolymer obtained by reacting an isocyanate group of a polyisocyanate with a hydroxyl group of a polyol in a molar ratio of 0.5 to 0.9, a polyfunctional polyol and an isocyanate curing agent is known (for example, refer to patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication 2016-176068

Disclosure of Invention

Problems to be solved by the invention

Conventionally known adhesives may not sufficiently inhibit contamination after the adhesive is peeled from the substrate. The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive having excellent contamination properties with an adherend after peeling.

Means for solving the problems

The adhesive composition of the present invention comprises a urethane resin (A) having a hydroxyl group and a curing agent (B), wherein the urethane resin (A) is a reaction product of a polyol (a 1) and a polyisocyanate (a 2), and the polyisocyanate (a 2) comprises a polyisocyanate (a 2-2) having 3 or more isocyanate groups.

ADVANTAGEOUS EFFECTS OF INVENTION

By using the adhesive composition of the present invention, an adhesive having excellent contamination of an adherend after peeling can be provided.

Detailed Description

The adhesive composition of the present invention comprises a urethane resin (a) and a curing agent (B).

The urethane resin (a) is a reaction product of a polyol (a 1) and a polyisocyanate (a 2).

The polyol (a 1) is a compound having 2 or more hydroxyl groups in 1 molecule, and preferably contains the polymer polyol (a 1-1), the polyol (a 1-2) having a carboxyl group, and if necessary, the chain extender (a 1-3).

The number average molecular weight of the polymer polyol (a 1-1) is preferably 500 or more, more preferably 700 or more, further preferably 900 or more, preferably 10000 or less, more preferably 5000 or less, further preferably 3000 or less, particularly preferably 2000 or less.

In the present invention, the number average molecular weight and the weight average molecular weight represent values measured by gel permeation chromatography based on polystyrene conversion.

As the polymer polyol (a 1-1), 1 or 2 or more kinds may be used, and examples thereof include polyether polyols, polyester polyols, polycarbonate polyols, hydroxyl group-containing liquid diene polymers, and the like.

Examples of the polyether polyol include: polyether polyol obtained by addition-polymerizing alkylene oxide using 1 or 2 or more kinds of compounds having 2 or more active hydrogen atoms (for example, 50 or more and less than 500 in molecular weight) as an initiator, or polyether polyol obtained by ring-opening-polymerizing cyclic ether using 1 or 2 or more kinds of compounds having 2 or more active hydrogen atoms (for example, 50 or more and less than 500 in molecular weight) as an initiator, if necessary.

As the compound having 2 or more active hydrogen atoms, 1 or 2 or more kinds may be used, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, 1, 6-hexanediol, bisphenol a, glycerol, trimethylolethane, trimethylolpropane, and the like.

The alkylene oxide may be 1 or 2 or more, and examples thereof include ethylene oxide, propylene oxide, butylene oxide, and epichlorohydrin. Examples of the cyclic ether include tetrahydrofuran and alkyl-substituted tetrahydrofuran.

Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol derivatives obtained by reacting tetrahydrofuran with alkyl-substituted tetrahydrofuran, and polytetramethylene glycol derivatives obtained by copolymerizing neopentyl glycol with tetrahydrofuran. Among them, polypropylene glycol, polytetramethylene glycol (PTMG), and polytetramethylene glycol derivatives (PTXG) are preferable as the polyether polyol.

The polyether polyol contains at least 10 mass% or more of a polyether polyol having an alkylene oxide unit having 4 or more carbon atoms. By containing an alkylene oxide unit having 4 or more carbon atoms, variation in surface characteristics can be easily suppressed.

In the polymer polyol (a 1-1), the content of the polyether polyol is preferably 50% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 100% by mass or less.

As the polyester polyol, for example, an esterification reaction product of a low molecular polyol and a polycarboxylic acid; ring-opening polymers of cyclic ester compounds such as epsilon-caprolactone; the esterification reaction product, a copolyester of a ring-opened polymer, and the like.

Examples of the polycarboxylic acid include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid, and anhydrides and esters thereof.

Examples of the polycarbonate polyol include reaction products of carbonates and/or phosgene and low-molecular polyols. As the above-mentioned carbonate, 1 or 2 or more kinds may be used, and examples thereof include aliphatic carbonates such as alkyl carbonates (e.g., methyl carbonate, ethyl carbonate, etc.), dialkyl carbonates (e.g., dimethyl carbonate, diethyl carbonate, etc.); carbonates containing an alicyclic structure (hereinafter, the term "containing an alicyclic structure" may be abbreviated as "alicyclic"); aromatic carbonates such as diphenyl carbonate. Among them, aliphatic carbonates and alicyclic carbonates are preferable, aliphatic carbonates are more preferable, and dialkyl carbonates are further preferable.

Examples of the low molecular weight polyol capable of reacting with the carbonate and phosgene include aliphatic polyols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1, 2-propanediol, 1, 3-propanediol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 5-hexanediol, 1, 6-hexanediol, 2, 5-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 11-undecanediol, 1, 12-dodecanediol, 2-methyl-1, 3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1, 3-propanediol, 3-methyl-1, 5-pentanediol, 2-ethyl-1, 3-hexanediol, 2-methyl-1, 8-octanediol; alicyclic polyols such as 1, 4-cyclohexanedimethanol; hydroquinone, resorcinol; aromatic polyols such as bisphenol a, bisphenol F, and 4,4' -biphenol.

The low molecular weight polyol is preferably an aliphatic polyol or an alicyclic polyol, more preferably an aliphatic polyol, and still more preferably 1, 2-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, or 1, 6-hexanediol.

As the above-mentioned polycarbonate polyol, an aliphatic polycarbonate polyol which is a reaction product of an aliphatic carbonate and an aliphatic polyol is preferable; alicyclic polycarbonate polyols and the like as reaction products of aliphatic carbonates and/or alicyclic carbonates with aliphatic polyols and/or alicyclic polyols.

In the above polyol (a 1), the content of the polymer polyol (a 1-1) is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and still more preferably 100% by mass or less.

As the above-mentioned polyhydric alcohol (a 1-2) having a carboxyl group, 1 or 2 or more kinds may be used, and examples thereof include hydroxy acids such as 2, 2-dimethylolpropionic acid, 2-dimethylolbutyric acid, and 2, 2-dimethylolvaleric acid; and a reaction product of the above-mentioned polyhydric alcohol having a carboxyl group and the above-mentioned polycarboxylic acid. As the above-mentioned polyhydric alcohol (a 1-2) having a carboxyl group, a hydroxy acid is preferable, and 2, 2-dimethylolpropionic acid is more preferable.

The content of the polyol (a 1-2) having a carboxyl group is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, and even more preferably not used, based on 100 parts by mass of the polymer polyol (a 1-1).

The hydroxyl group-containing liquid diene polymer is a liquid diene polymer containing hydroxyl groups at the molecular chain ends and/or in the molecular chain; and/or the hydrogenated product of the liquid diene polymer, for example, a hydroxyl-terminated polybutadiene, a hydroxyl-terminated polyisoprene, a hydroxyl-terminated hydrogenated polybutadiene, a hydroxyl-terminated hydrogenated polyisoprene, or the like.

The hydroxyl group may be located at any of the molecular chain end and the molecular chain interior, and is particularly preferably located at the molecular chain end.

In the polyol (a 1), the content of the polymer polyol (a 1-1) is preferably 50% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 100% by mass or less.

As the chain extender (a 1-3), 1 or 2 or more kinds may be used, and examples thereof include a compound having 2 or more active hydrogen atoms, a polyamine, and the like. Examples of the compound having 2 or more active hydrogen atoms include aliphatic chain extenders such as ethylene glycol, 1, 2-propylene glycol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol, 3' -dimethylol heptane, neopentyl glycol, 3-bis (hydroxymethyl) heptane, diethylene glycol, dipropylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, glycerin, and trimethylolpropane; alicyclic chain extenders such as 1, 2-cyclobutanediol, 1, 3-cyclopentanediol, 1, 4-cyclohexanediol, cycloheptanediol, cyclooctanediol, 1, 4-cyclohexanedimethanol, hydroxypropyl cyclohexanol, tricyclo [5.2.1.0] decane-2, 6-dimethanol, bicyclo [4.3.0] nonanediol, dicyclohexyl diol, bicyclo [4.3.0] nonanediol, spiro [3.4] octanediol, butylcyclohexanediol, 1 '-dicyclohexylenediol (1, 1' -dicyclohexylidenediol), cyclohexanetriol, hydrogenated bisphenol a, 1, 3-adamantanediol, etc., preferably aliphatic alkylene glycols such as ethylene glycol, propylene glycol, 1, 4-butanediol, 1, 6-hexanediol, diethylene glycol, neopentyl glycol, 1, 3-butanediol, etc.; alicyclic ethylene glycol such as cyclohexanedimethanol, and the like. Examples of the polyamine include polyamine chain extenders such as ethylenediamine, 1, 2-propylenediamine, 1, 6-hexamethylenediamine, piperazine, 2, 5-dimethylpiperazine, isophoronediamine, 4 '-dicyclohexylmethane diamine, 3' -dimethyl-4, 4 '-dicyclohexylmethane diamine, 1, 4-cyclohexanediamine, N-hydroxymethylaminoethylamine, N-ethylaminoethylamine, N-methylaminopropylamine, diethylenetriamine, dipropylenetriamine, triethylenetetramine, hydrazine, N' -dimethylhydrazine, 1, 6-hexamethylenedihydrazide, succinic dihydrazide, adipic dihydrazide, glutaric dihydrazide, sebacic dihydrazide, isophthalic dihydrazide, β -semicarbazide propionyl, 3-semicarbazide-propyl-hydrazino formate, semicarbazide-3-semicarbazide methyl-3, 5-trimethylcyclohexane and the like.

When the chain extender (a 1-3) is contained, the content thereof is preferably 0 to 5% by mass, more preferably 0 to 3% by mass, and even more preferably 0 to 1% by mass, relative to the polyol (a 1).

The polyol (a 1) may contain other polyols (a 1-4) than the polymer polyol (a 1-1), the polyol (a 1-2) having a carboxyl group and the chain extender (a 1-3).

The polyisocyanate (a 2) contains a polyisocyanate (a 2-2) having 3 or more isocyanate groups.

The molar ratio (NCO/OH) of the isocyanate groups contained in the polyisocyanate (a 2) to the hydroxyl groups contained in the polyol (a 1) is preferably 0.4 or more, more preferably 0.5 or more, further preferably 0.55 or more, preferably 0.98 or less, more preferably 0.95 or less, further preferably 0.9 or less.

As the polyisocyanate (a 2-2) having 3 or more isocyanate groups, 1 or 2 or more types may be used, and examples thereof include aromatic diisocyanates such as diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate and the like; aliphatic diisocyanates such as hexamethylene diisocyanate and lysine diisocyanate; biurets, isocyanurate, adducts, etc. of alicyclic diisocyanates such as isophorone diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, 4' -dicyclohexylmethane diisocyanate, 2, 4-and/or 2, 6-methylcyclohexane diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexylene-1, 2-dicarboxylate, and 2, 5-and/or 2, 6-norbornane diisocyanate, dimer acid diisocyanate, bicycloheptane triisocyanate, hydrogenated xylylene diisocyanate, etc.

The polyisocyanate (a 2) may be a diisocyanate (a 2-1) having 2 isocyanate groups, in addition to the polyisocyanate (a 2-2) having 3 or more isocyanate groups.

As the diisocyanate (a 2-1), 1 or more kinds or 2 or more of them can be used, and examples thereof include aromatic diisocyanates such as diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, xylylene diisocyanate, toluene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate and the like; aliphatic diisocyanates such as hexamethylene diisocyanate and lysine diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, 4' -dicyclohexylmethane diisocyanate, 2, 4-and/or 2, 6-methylcyclohexane diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexylene-1, 2-dicarboxylate and 2, 5-and/or 2, 6-norbornane diisocyanate, dimer acid diisocyanate, bicycloheptane triisocyanate, hydrogenated xylylene diisocyanate, and the like. Among them, aliphatic diisocyanate and alicyclic diisocyanate are preferable.

The content of the polyisocyanate (a 2) is adjusted by the molar ratio (isocyanate group/hydroxyl group) of the average functional group number of the polyisocyanate (a 2) to the hydroxyl group contained in the polyol (a 1).

The average functional group number of the polyisocyanate (a 2) is preferably 2.05 to 4, more preferably 2.1 to 3.

The molar ratio (isocyanate group/hydroxyl group) of the isocyanate group contained in the polyisocyanate (a 2) to the hydroxyl group contained in the polyol (a 1) is 0.4 or more, preferably 0.5 or more and less than 1, preferably 0.95 or less, and more preferably 0.90 or less.

The isocyanate-terminated prepolymer may be obtained by reacting the isocyanate groups contained in the polyisocyanate (a 2) with the hydroxyl groups contained in the polyol (a 1) in a molar ratio (isocyanate groups/hydroxyl groups) of 1.0 or more in excess of isocyanate groups, and then reacting the resultant prepolymer with the chain extender (a 1-3). The molar ratio (isocyanate group/hydroxyl group) of the isocyanate group contained in the polyisocyanate (a 2) to the hydroxyl group contained in the polyol (a 1) at the time of producing the isocyanate-terminated prepolymer is 1.0 or more, preferably 1.05 or more, more preferably 1.1 or more, preferably less than 3.0, more preferably 2.5 or less, and even more preferably 2.0 or less.

The urethane resin (a) may be obtained by further reacting the reaction product of the polyol (a 1), the polyisocyanate (a 2), and the chain extender (a 1-3) which is optionally used, with a blocking agent. The isocyanate groups can be deactivated by using a blocking agent.

The blocking agent is preferably an alcohol, and examples thereof include monofunctional alcohols such as methanol, ethanol, propanol, and butanol; difunctional alcohols such as 1, 2-propanediol and 1, 3-butanediol; a polyfunctional polyol; alkanolamine compounds such as alkanolamine (e.g., ethanolamine, etc.), dialkanolamine (e.g., diethanolamine, etc.), etc. If a polyalkanolamine compound is used, a hydroxyl group may be further introduced into the terminal of the urethane resin (a), and thus may be used as needed.

When the blocking agent is used, the molar ratio of the active hydrogen atom-containing group contained in the blocking agent to the isocyanate group contained in the polyisocyanate (a 2) is preferably 1.0 or more, more preferably 1.2 or more, still more preferably 1.5 or more, preferably 10.0 or less, more preferably 5.0 or less, and still more preferably 3.0 or less.

The number average molecular weight of the urethane resin (a) is preferably 7000 or more, more preferably 9000 or more, further preferably 10000 or more, preferably 200000 or less, more preferably 150000 or less, further preferably 100000 or less.

The molecular weight dispersity of the urethane resin (a) is preferably 1.8 or more, more preferably 2 or more, further preferably 2.3 or more, preferably 20 or less, and more preferably 10 or less.

In the present specification, the number average molecular weight and the weight average molecular weight can be measured as converted values using polystyrene as a standard sample by gel permeation chromatography.

The urethane resin (a) can be produced by reacting the polyol (a 1) with the polyisocyanate (a 2), and if necessary, further reacting with the chain extender (a 1-3) and/or the blocking agent. The reaction may be carried out in the presence of an organic solvent, and a urethanization catalyst may coexist when the reaction is carried out.

As the organic solvent, 1 or 2 or more kinds may be used, and examples thereof include aromatic hydrocarbon solvents such as toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and 3-pentanone; ether solvents such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, and ethyl carbitol; nitrile solvents such as acetonitrile, propionitrile, isobutyronitrile, valeronitrile, etc.; sulfoxide solvents such as dimethyl sulfoxide; amide solvents such as methyl formamide, dimethylacetamide and N-methyl-2-pyrrolidone, and the like.

Examples of the urethane catalyst include nitrogen-containing compounds such as triethylamine, triethylenediamine and N-methylmorpholine, metal salts such as potassium acetate, zinc stearate and tin octoate, and organometallic compounds such as dibutyltin laurate, dioctyltin di-neodecanoate and zirconium acetylacetonate.

The content of the urethane resin (a) in the nonvolatile component of the adhesive composition is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, preferably 99% by mass or less, and still more preferably 98% by mass or less.

The nonvolatile component of the adhesive composition means a component of the adhesive composition other than a solvent.

The curing agent (B) may be any curing agent that can react with hydroxyl groups of the urethane resin (a) to form three-dimensional crosslinks, and for example, a polyisocyanate curing agent may be used. These curing agents may be used alone or in combination of 2 or more.

As the polyisocyanate curing agent, polyisocyanates such as toluene diisocyanate, chlorobenzene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and xylylene diisocyanate; trimethylol propane adduct of hexamethylene diisocyanate, trimethylol propane adduct of toluene diisocyanate, trimethylol propane adduct of isophorone diisocyanate, trimethylol propane adduct of xylylene diisocyanate, isocyanurate body of hexamethylene diisocyanate, isocyanurate body of toluene diisocyanate, isocyanurate body of isophorone diisocyanate, isocyanurate body of xylylene diisocyanate, and the like. These curing agents may be used alone or in combination of 2 or more.

The molar ratio of the hydroxyl groups in the urethane resin (a) to the hydroxyl-reactive groups contained in the curing agent (B) (hydroxyl groups/hydroxyl-reactive functional groups) is preferably 1 or more, more preferably 1.2 or more, still more preferably 1.5 or more, preferably 5 or less, still more preferably 4 or less, and still more preferably 3 or less.

The adhesive composition preferably further comprises an antioxidant. As the antioxidant, 1 or 2 or more kinds may be used, and examples thereof include primary antioxidants such as hindered phenol compounds; secondary antioxidants such as phosphorus compounds and sulfur compounds.

As the hindered phenol compound, 1 or 2 or more kinds may be used, and examples thereof include triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate]Pentaerythritol tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] octadecyl, thiodiethylenebis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ]]Phenylpropionic acid-3, 5-bis (1, 1-dimethylethyl) -4-hydroxy-C ₇ -C ₉ Side chain alkyl esters, 4, 6-bis (dodecylthiomethyl) -o-cresol, the reaction product of N-phenylaniline with 2, 4-trimethylpentene, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate, 3, 9-bis [2- [3- (tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy ] -1, 1-dimethylethyl]2,4,8, 10-tetraoxaspiro [ 5.5 ] undecane, 2, 6-di-tert-butyl-4-methylphenol, 2' -methylenebis (4-methyl-6-tert-butylphenol), 2, 5-di-tert-amylhydroquinone and the like.

As the above phosphorus compound, 1 or 2 or more kinds may be used, examples thereof include triphenylphosphine, bis (2, 4-di-tert-butyl-6-methylphenyl) =phosphite, triphenyl phosphite, tris (nonylphenyl) phosphite, tris (2, 4-dibutylphenyl) phosphite, tris (2, 4-dibutyl-5-methylphenyl) phosphite, tris [ 2-tert-butyl-4- (3-butyl-4-hydroxy-5-methylphenylsulfanyl) -5-methylphenyl ] phosphite, tris (2, 4-di-tert-butylphenyl) phosphite, tridecyl phosphite, octyldiphenyl phosphite, bis (decyl) monophenyl phosphite, ditridecyl) pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, bis (2, 4-dibutylphenyl) pentaerythritol diphosphite, bis (2, 6-dibutyl-4-methylphenyl) pentaerythritol diphosphite, bis (2, 4, 6-tributylphenyl) pentaerythritol diphosphite, bis (2, 4-dicumylphenyl) dipentaerythritol, tetra (tridecyl) pentaerythritol diphosphite, tetra (4-diisobutyl) -4-butylphenyl) bisphenol, tetra (4-diisobutyl) phenol, 4' -di-butylphenyl) diphosphite, hexa (tridecyl) -1, 3-tris (2-methyl-4-hydroxy-5-butylphenyl) butane triphosphite, tetra (2, 4-dibutylphenyl) biphenylene diphosphonite, 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 2' -methylenebis (4, 6-butylphenyl) -2-ethylhexyl phosphite, 2' -methylenebis (4, 6-butylphenyl) -octadecyl phosphite, 2' -ethylenebis (4, 6-dibutylphenyl) fluorophosphite, tris (2- [2, 4,8, 10-tetrabutyldibenzo [ d, f ] [ 1,3, 2] dioxaphosphepin (dioxaphosphepin) -6-yl) oxy ethyl ] amine, 2-ethyl-2-butylpropanediol, 2,4, 6-tributylphenol phosphite, and the like.

Examples of the sulfur compound include 1 or 2 or more kinds of sulfur compounds, such as didodecyl-3, 3 '-thiopropionate, dilauryl-3, 3' -thiodipropionate, laurylthio dithiopropionate, bis [ 2-methyl-4- (3-n-alkylthio) -5-tert-butylphenyl ] sulfide, β -laurylthiopropionate, 2-mercaptobenzimidazole, 2-mercapto-5-methylbenzimidazole, and distearyl-3, 3 '-thiodipropionate, tetramethylene-3-laurylthiopropionate, distearyl-3, 3' -methyl-3, 3 '-thiodipropionate, laurylstearyl-3, 3' -thiodipropionate, and β -laurylthiopropionate.

Among them, a primary antioxidant such as a hindered phenol compound is preferable.

The content of the antioxidant is preferably 0.1 part by mass or more, more preferably 0.5 parts by mass or more, further preferably 1 part by mass or more, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, further preferably 3 parts by mass or less, based on 100 parts by mass of the urethane resin.

The adhesive composition preferably further comprises a reaction retarder. The reaction retarder has an effect of retarding the reaction of the curing agent, and is preferably an isocyanate curing agent. Examples of the reaction retarder include compounds exhibiting keto-enol tautomerism, such as β -diketone compounds. By including the reaction retarder, the reaction between the isocyanate group and the hydroxyl group in the adhesive composition can be easily controlled, and the pot life (pot life) can be easily adjusted. The boiling point of the reaction retarder is preferably 100 ℃ or lower. By setting the boiling point of the reaction retarder to 100 ℃ or lower, the adhesive sheet is volatilized under dry conditions during processing, and the reaction between the isocyanate group and the hydroxyl group is not hindered during aging, whereby curing can be completed during aging.

As the reaction retarder (preferably, a β -diketone compound) of the isocyanate curing agent, 1 or 2 or more kinds of β -diketones such as acetylacetone, 2, 4-hexanedione, 3, 5-heptanedione, 2-methylhexane-3, 5-dione, 6-methylheptane-2, 4-dione, 2, 6-dimethylheptane-3, 5-dione and the like can be used; acetoacetates such as methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, and t-butyl acetoacetate; propionyl acetate esters such as ethyl propionylacetate, isopropyl propionylacetate, tert-butyl propionylacetate and the like; isobutyryl acetates such as ethyl isobutyrylacetate, isopropyl isobutyrylacetate, t-butyl isobutyrylacetate, and the like; malonates such as methyl malonate and ethyl malonate; etc.

The content of the reaction retarder is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, further preferably 1 part by mass or more, preferably 10 parts by mass or less, more preferably 7 parts by mass or less, further preferably 5 parts by mass or less, based on 100 parts by mass of the urethane resin.

The adhesive composition may further comprise a curing catalyst. The curing catalyst may be the same as those exemplified as the urethane catalyst and the epoxy curing catalyst. When the curing catalyst is contained, the content thereof is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, still more preferably 0.01 parts by mass or more, preferably 1 part by mass or less, more preferably 0.1 parts by mass or less, still more preferably 0.05 parts by mass or less, based on 100 parts by mass of the urethane resin (a).

The adhesive composition may further comprise a plasticizer. Examples of the plasticizer include aliphatic polycarboxylic acid esters such as adipic acid esters, citric acid esters, sebacic acid esters, azelaic acid esters, and maleic acid esters; aromatic polycarboxylic acid esters such as terephthalic acid esters, isophthalic acid esters, phthalic acid esters, trimellitic acid esters, and benzoic acid esters; an ether modified polyester; an epoxy modified polyester; polyesters formed from polycarboxylic acids and polyols, and the like.

When the plasticizer is contained, the content of the plasticizer is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less, based on 100 parts by mass of the urethane resin (a).

The adhesive composition may further comprise a solvent. The solvent may be the same as the compound exemplified as the organic solvent. When the organic solvent is contained, the content thereof in the adhesive composition is preferably 20 mass% or more, more preferably 30 mass% or more, preferably 80 mass% or less, more preferably 70 mass% or less. In the adhesive composition of the present invention, the content of water in the solvent is preferably 10 mass% or less, more preferably 5 mass% or less, still more preferably 1 mass% or less, and the lower limit is 0 mass%.

In the adhesive composition, the area ratio of the low molecular weight component having a maximum value of 2000 to 6000 in the elution profile of the gel permeation chromatography is preferably less than 5% by mass, more preferably 3% by mass or less, still more preferably 1% by mass or less, and most preferably 0% by mass.

The adhesive composition may further contain a silane coupling agent, an antioxidant, a light stabilizer, an antirust agent, a thixotropic property imparting agent, a sensitizer, a polymerization inhibitor, a leveling agent, a tackifier, an antistatic agent, a flame retardant, and the like as other additives. In the adhesive composition, the content of the other additive is preferably 10 mass% or less, more preferably 5 mass% or less, still more preferably 1 mass% or less, and the lower limit is 0 mass%.

The adhesive composition is applied to a substrate, the solvent is removed as needed, and the substrate is aged as needed, whereby an adhesive layer which is a cured product of the adhesive composition can be formed. The thickness of the adhesive layer is preferably 1 μm or more, more preferably 2 μm or more, further preferably 5 μm or more, preferably 200 μm or less, more preferably 150 μm or less, further preferably 100 μm or less.

As a method for forming a sheet using the adhesive composition, for example, a method of applying the adhesive composition to a plastic substrate and drying and curing the same is mentioned.

As the plastic base material, for example, polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and the like can be used; polyolefin resins such as polyethylene and polypropylene; a polyacrylic resin; polyvinyl chloride resin; polypropylene ethylene vinyl alcohol; a polyvinyl alcohol resin; a polyurethane resin; a polyamide resin; polyimide resin, and the like. The surface of these plastic substrates may be subjected to a mold release treatment, an antistatic treatment, a corona treatment, or the like. The thickness of the plastic base material is, for example, in the range of 10 to 200. Mu.m.

Examples of the method for applying the adhesive composition to the plastic substrate include coating methods using a roll coater, a gravure coater, a reverse coater, a spray coater, an air knife coater, a die coater, and the like.

The method of applying the adhesive composition to the plastic substrate and then drying the adhesive composition includes, for example, a method of drying at 50 to 120℃for 30 seconds to 30 minutes. In addition, after drying, aging may be performed at a temperature of 20 to 50 ℃ in order to promote the curing reaction.

The adhesive layer, which is a cured product of the adhesive composition, can suppress the change in the surface characteristics of the substrate before and after the release thereof, and is useful as a surface protective film, particularly useful as a surface protective film for protecting an information display portion of an electronic device such as a display device. The film using the adhesive layer which is a cured product of the adhesive composition has a property (wettability) of rapidly adhering to and spreading on the substrate when in contact with the substrate, and is useful as a surface protective film.

Examples

The present invention will be described more specifically below with reference to examples.

The number average molecular weight and the weight average molecular weight of the urethane resin were measured by the following GPC measurement method.

GPC measurement method

Measurement device: high-speed GPC apparatus (HLC-8220 GPC, manufactured by Tosoh Co., ltd.)

Column: the following columns manufactured by Tosoh corporation were connected in series for use.

(1) TSK-GEL HXL-H (protective column)

(2)TSK-GEL GMHXL

(3)TSK-GEL GMHXL

(4)TSK-GEL GMHXL

(5)TSK-GEL GMHXL

Sample concentration: diluted to 4mg/mL with tetrahydrofuran

Mobile phase solvent: tetrahydrofuran (THF)

Flow rate: 1.0mL/min

Injection amount: 100 mu L

Column temperature: 40 DEG C

Standard sample: standard curves were made using standard polystyrene as described below.

(Standard polystyrene)

TSKgel Standard polystyrene A-500 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene A-1000 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene A-2500 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene A-5000 manufactured by Tosoh Co., ltd "

"TSKge1 Standard polystyrene F-1" manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-2 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-4 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-10 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-20 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-40 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-80 manufactured by Tosoh Co., ltd "

"TSKge1 Standard polystyrene F-128" from Tosoh Co., ltd "

TSKgel Standard polystyrene F-288 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-550 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-850 manufactured by Tosoh Co., ltd "

Production example 1 production of urethane resin (I)

Into a 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, 488.84 parts by mass of polytetramethylene ether glycol (number average molecular weight: 1971.9, hydroxyl value: 56.9) was added under nitrogen flow, and after mixing uniformly, 10.64 parts by mass of biuret having 3 isocyanate groups (Duranate 24A-100, manufactured by Asahi chemical Co., ltd.; NCO.; 23.5% by mass, hereinafter abbreviated as "24A-100") was added, and subsequently, 0.06 parts by mass of dibutyltin dilaurate was added, and the reaction was carried out at 100℃for about 4 hours while stirring, confirming that the isocyanate groups disappeared, to thereby obtain a branched urethane prepolymer (solid content 100%) having hydroxyl groups at the molecular terminals.

Next, the urethane prepolymer obtained by the above method was cooled to 50 ℃, 131.85 parts by mass of methyl ethyl ketone was added, and after uniform mixing, 28.35 parts by mass of hexamethylene diisocyanate having 2 isocyanate groups was added, next, 0.12 part by mass of dibutyltin dilaurate was added, and after confirming disappearance of the isocyanate groups by reaction at 75 ℃ for about 8 hours with stirring, 395.86 parts by mass of methyl ethyl ketone was added, and the mixture was cooled to room temperature to obtain a methyl ethyl ketone solution (solid content 50%) of the urethane resin (I). In the molecular weight distribution of the urethane resin (I) obtained by GPC, only 1 peak having a maximum value at 63836 in weight average molecular weight was detected, the number average molecular weight (Mn) was 9105, the weight average molecular weight (Mw) was 63836, and the molecular weight dispersity (Mw/Mn) was 7.01. In addition, the molar ratio (NCO/hydroxyl group) was 0.80.

Production example 2 production of urethane resin (II)

In a 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, 575.37 parts by mass of polytetramethylene ether glycol (number average molecular weight: 1971.9, hydroxyl value: 56.9) was added under a nitrogen flow, and after mixing uniformly, 34.31 parts by mass of hexamethylene diisocyanate having 2 isocyanate groups was added, and subsequently 0.13 part by mass of dibutyltin dilaurate was added, followed by reaction at 90℃for about 2 hours with stirring, disappearance of isocyanate groups was confirmed, whereby a linear urethane prepolymer (solid content 100%) having hydroxyl groups at the molecular terminals was obtained.

Next, the urethane prepolymer obtained by the above method was cooled to 50 ℃, 155.55 parts by mass of methyl ethyl ketone was added, and after mixing uniformly, 12.91 parts by mass of "24A-100" was added, and after confirming the disappearance of the isocyanate group by reaction at 75 ℃ for about 8 hours with stirring, 259.46 parts by mass of methyl ethyl ketone was added, and cooled to room temperature, to obtain a methyl ethyl ketone solution (solid content 50%) of the urethane resin (II). In the molecular weight distribution of the urethane resin (II) obtained by GPC, 2 peaks of a peak a having a maximum value at a weight average molecular weight of 1190946 and a main peak B having a maximum value at a weight average molecular weight of 56129 were detected, the number average molecular weight (Mn) of the main peak B was 7524, the weight average molecular weight (Mw) was 56129, and the molecular weight dispersity (Mw/Mn) was 7.46. In addition, the molar ratio (NCO/hydroxyl group) was 0.83.

Production example 3 production of urethane resin (III)

Into a 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, 493.10 parts by mass of polytetramethylene ether glycol (number average molecular weight: 1971.9, hydroxyl value: 56.9), 142.85 parts by mass of polytetramethylene ether glycol (number average molecular weight: 1011.8, hydroxyl value: 110.9) and 125.68 parts by mass of methyl ethyl ketone were charged under a nitrogen flow, and after mixing uniformly, 78.28 parts by mass of isocyanurate having 3 isocyanate groups (NCO; 23.0% by mass "Duranate TUL-100", manufactured by Asahi chemical Co., ltd.) was charged, followed by 0.36 part by adding dibutyltin dilaurate, and reacting at 75℃for about 6 hours while stirring. After confirming the disappearance of the isocyanate group, 535.24 parts by mass of methyl ethyl ketone was added, and the mixture was cooled to room temperature to obtain a methyl ethyl ketone solution (solid content: 50%) of the urethane resin (III). In the molecular weight distribution of the urethane resin obtained by GPC, only 1 peak having a maximum value at a weight average molecular weight of 74504 was detected, the number average molecular weight (Mn) was 4331, the weight average molecular weight (Mw) was 74504, and the molecular weight dispersity (Mw/Mn) was 17.2. In addition, the molar ratio (NCO/hydroxyl group) was 0.55.

Production example 4 production of urethane resin (IV)

A4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube was charged with 211.83 parts by mass of polyester polyol ("kuraray polyol P1010", manufactured by kuraray, inc., number average molecular weight; 1002.8, hydroxyl value: 111.9, hereinafter abbreviated as "P1010") and 275.73 parts by mass of ethyl acetate under a nitrogen flow, and after mixing uniformly, 63.96 parts by mass of hexamethylene diisocyanate was added, and then 0.01 part by mass of dioctyltin di-neodecanoate was added, and reacted at 70℃for about 4 hours, to thereby obtain an ethyl acetate solution (solid content) of a urethane prepolymer having an isocyanate group at a molecular end.

Next, an ethyl acetate solution of the urethane prepolymer obtained by the above method was cooled to 40 ℃, polyoxyethylene polyoxypropylene triol (SANIX GL-3000, made by san yo chemical Co., ltd., "mol ratio [ EO/PO ] =25/75, number average molecular weight; 3, 077.1, hydroxyl value: 54.7) 605.71 parts by mass, ethyl acetate 198.62 parts by mass, and after uniformly mixing, dioctyltin di neodecanoate was added in 0.01 parts by mass, reacted at 70 ℃ for about 6 hours, 1, 3-butanediol 2.20 parts by mass as a blocking agent was added at a time when the NCO% reached 0.05% or less, reacted at 70 ℃ for about 2 hours, and after confirming that the NCO disappeared, ethyl acetate 406.84 parts by mass was added, cooled to room temperature, to obtain an ethyl acetate solution (solid content 50%) of the urethane resin (IV).

In the molecular weight distribution of the urethane resin (IV) obtained by GPC, 2 peaks of a main peak a having a maximum value at a weight average molecular weight of 208190 and a peak B having a maximum value at a weight average molecular weight of 2383 were detected, the number average molecular weight (Mn) of the main peak a was 26096, the weight average molecular weight (Mw) was 208190, and the molecular weight dispersity (Mw/Mn) was 7.98. The area ratio of peak B was 10.16%. In addition, the molar ratio (NCO/hydroxyl group) was 0.75.

PREPARATION EXAMPLE 5 preparation of urethane resin (V)

To a 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, 489.09 parts by mass of polytetramethylene ether glycol (number average molecular weight: 1971.9, hydroxyl value: 56.9) and 142.25 parts by mass of polytetramethylene ether glycol (number average molecular weight: 1011.8, hydroxyl value: 110.9) were added under a nitrogen stream, 420.42 parts by mass of methyl ethyl ketone was added, and after mixing uniformly, 79.91 parts by mass of isophorone diisocyanate having 2 isocyanate groups was added, and subsequently 0.47 part by mass of dibutyltin dilaurate was added, and reacted at 75 ℃ for about 6 hours while stirring. After confirming the disappearance of the isocyanate group, 535.24 parts by mass of methyl ethyl ketone was added, and the mixture was cooled to room temperature to obtain a methyl ethyl ketone solution (solid content: 50%) of the urethane resin (III). In the molecular weight distribution of the urethane resin obtained by GPC, only 1 peak having a maximum value at a weight average molecular weight of 32640 was detected, the number average molecular weight (Mn) was 7336, the weight average molecular weight (Mw) was 32640, and the molecular weight dispersity (Mw/Mn) was 4.4. In addition, the molar ratio (NCO/hydroxyl group) was 0.93.

EXAMPLE 1 urethane resin (I)

Immediately before the production of the sheet, 3.62 parts by mass of an isocyanurate of hexamethylene diisocyanate (Duranate TKA-100, NCO; 21.7% by mass, hereinafter abbreviated as "TKA-100") as a crosslinking agent, 1.00 parts by mass of a 1% methyl ethyl ketone solution of dioctyltin di-neodecanoate as a curing catalyst, 2.50 parts by mass of a 20% methyl ethyl ketone solution of "Irganox1010" (BASF Japan, hereinafter abbreviated as "Ir 1010") as an antioxidant, and 27.68 parts by mass were blended into 100 parts by mass of a methyl ethyl ketone solution of the urethane resin (I) (solid content 50%) obtained in production example 1, to obtain a binder composition (A) (solid content 40%). The adhesive composition (A) thus obtained was applied to the surface of a polyethylene terephthalate film having a thickness of 50. Mu.m, and dried at 80℃for 3 minutes so that the film thickness after drying became 10. Mu.m. A polyethylene terephthalate film having a thickness of 50 μm, the surface of which was subjected to release treatment, was laminated thereon, and cured at 40℃for 3 days, whereby an adhesive sheet of example 1 was obtained.

The adhesive tapes of examples 2 to 3 and comparative examples 1 to 2 were obtained by the same method as in example 1 except that the raw materials were replaced with the types and amounts shown in table 1.

TABLE 1

[ method for measuring adhesive force ]

The surface protective films obtained in examples and comparative examples were cut for Cheng Kuandu mm, and were used as test pieces. The release film was peeled off from the test piece, and the glass plate was attached by reciprocation 2 times with a 2kg roller so that the adhesion area became 20mm×60 mm. After 24 hours of adhesion, 180-degree peel strength was measured at 23℃under a 50% humidity atmosphere as adhesion force (N/25 mm). The adhesion was evaluated as follows.

O: 0.05 or more and less than 0.50

Delta: 0.50 or more and less than 1.00

X: 1.00 or more

[ method for evaluating contamination ]

The pressure-sensitive adhesive sheets obtained in examples and comparative examples were cut into a size of 30mm×60mm, and the sheets were used as test pieces, from which a release film was peeled off and attached to a glass plate. At this time, bubbles were allowed to enter between the sheet and the glass plate. The test piece was left to stand at 85℃and a humidity of 85% for 72 hours. After the glass plate was left to stand at 23℃for 1 hour, the sheet was peeled off from the glass plate by hand, and the lower portion of the glass plate was irradiated with an LED lamp to visually observe the contamination state, and the evaluation was performed as follows.

"good" is shown in the following description: the glass plate is completely free of contamination.

"Δ": contamination was confirmed in a part of the glass plate.

"×": contamination or detachment of the cured product of the adhesive composition was confirmed on the entire surface of the glass plate.

The evaluation results are shown in table 1.

TABLE 2

As described above, the adhesive composition of the present invention has excellent adhesion and contamination resistance to adherends.

On the other hand, in comparative example 1, the urethane resin was branched by using a triol instead of the polyisocyanate (a 2-2) having 3 or more isocyanate groups, and thus the contamination resistance by the adherend was poor. In addition, comparative example 2 is a straight-chain urethane resin, but the adhesion and the contamination resistance of the adherend are poor.

Claims (7)

1. An adhesive composition comprising a urethane resin (A) having a hydroxyl group and a curing agent (B),

the urethane resin (A) is a reaction product of a polyol (a 1) and a polyisocyanate (a 2),

the polyol (a 1) contains a polyether polyol having an alkylene oxide unit having 4 or more carbon atoms in a proportion of 100 mass%,

the polyisocyanate (a 2) comprises a polyisocyanate (a 2-2) having 3 or more isocyanate groups,

in the elution profile of the urethane resin (A) in the gel permeation chromatography measurement, the area ratio of the low molecular weight component having a maximum value of 2000 to 6000 in the weight average molecular weight is 0%.

2. The adhesive composition according to claim 1, wherein a molar ratio of isocyanate groups contained in the polyisocyanate (a 2) to hydroxyl groups contained in the polyol (a 1), i.e., NCO/OH, is 0.4 or more and 0.9 or less.

3. The adhesive composition of claim 1 or 2, further comprising an antioxidant.

4. The adhesive composition of claim 1 or 2, further comprising a reaction retarder.

5. The adhesive composition of claim 1 or 2, further comprising a plasticizer.

6. An adhesive sheet formed from the adhesive composition according to any one of claims 1 to 5.

7. A surface protective film comprising the adhesive sheet according to claim 6.