JP6256648B1 - Adhesive and pressure-sensitive adhesive sheet, laminate and display device using the same - Google Patents

Abstract

A pressure-sensitive adhesive capable of forming a highly smooth pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet using the same, and a laminate are solved. A urethane prepolymer (A), which is a reaction product of a polyol (a) and a polyisocyanate (b), an isocyanate curing agent (B), and a polyfunctional polyol (F). A) is a pressure-sensitive adhesive having a molecular weight dispersity of 1.5 or more and less than 4, and the polyfunctional polyol (F) has 3 or more hydroxyl groups in one molecule and has a primary hydroxyl group at the molecular end. [Selection figure] None

Description

  The present invention relates to a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet using the same, a laminate, and a display device.

  Display devices such as a flat panel display such as a liquid crystal display (LCD) and an organic electroluminescence display (OELD), a touch panel display in which a flat panel display and a touch panel are combined, are a television (TV), a personal computer (PC), a portable information Widely used in terminals and the like.

  Conventionally, an adhesive sheet in which an adhesive layer is formed on a base sheet has been widely used as a surface protective sheet for protecting an optical member used in a display device from adhesion of scratches and dust.

  In general, an adhesive containing an acrylic resin or a urethane resin is often used for the adhesive layer of the surface protective sheet. Among them, a pressure-sensitive adhesive containing a urethane resin (hereinafter referred to as a urethane pressure-sensitive adhesive) is used because it is excellent in moderate adhesive force and removability with respect to various adherends typified by glass.

  By the way, in recent years, the productivity improvement of the surface protection sheet has been demanded more than before, and for this purpose, a pressure sensitive adhesive having a wide coating suitability has been demanded. However, when the adhesive is applied with a wide coating machine, it is difficult to obtain a uniform coating film due to the difference in how hot air hits in the drying oven (drying unevenness). There were problems such as the formation of fine aggregates.

  Moreover, when sticking an adhesive sheet to an adherend, if the positioning of the sticking fails, an operation of once peeling and sticking the adhesive sheet is required. In that case, if the peeling is interrupted in the middle of the peeling process, a line (streak) enters the adhesive layer at the peeled boundary position (the peeling line remains), and the adhesive sheet is reused (reused) There was a problem that it was impossible.

  Patent Document 1 discloses a urethane prepolymer having a molecular weight dispersity of 4 to 12, in which a hydroxyl group of polyol (a) and an isocyanate group of polyisocyanate (b) are reacted at a molar ratio of NCO / OH = 0.5 to 0.9. An adhesive containing a polymer (A), a polyfunctional polyol (B) and an isocyanate curing agent (C) and an adhesive sheet using the same are disclosed. This pressure-sensitive adhesive is said to be excellent in terms of wettability to an adherend, adhesion to a curved surface, and removability. However, as described above, there are problems such as poor appearance when the pressure-sensitive adhesive is applied in a wide width and peeling line residue.

Japanese Patent Laid-Open No. 2006-176068

  An object of this invention is to provide the adhesive which can form the adhesive layer with high smoothness from which the problem of the peeling line residue was eliminated, an adhesive sheet using the same, and a laminated body.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the adhesive shown below, and have completed the present invention.

That is, the embodiment of the present invention includes a hydroxyl group-containing urethane prepolymer (A) which is a reaction product of the polyol (a) and the polyisocyanate (b), an isocyanate curing agent (B) and a polyfunctional polyol (F).
The urethane prepolymer (A) has a molecular weight dispersity of 1.5 or more and less than 4,
The polyfunctional polyol (F) is a pressure-sensitive adhesive having 3 or more hydroxyl groups in one molecule and having a primary hydroxyl group at the molecular end.

An embodiment of the present invention is the pressure-sensitive adhesive, wherein the polyol (a) includes one or more selected from the group consisting of polyether polyol, polyester polyol, and polybutadiene-modified polyol.

Moreover, the embodiment of this invention is the said adhesive containing 2-50 mass parts of said polyfunctional polyols (F) with respect to 100 mass parts of said urethane prepolymers (A).

Moreover, the embodiment of the present invention is the pressure-sensitive adhesive further including a plasticizer (C).

Moreover, the embodiment of this invention is the said adhesive which contains antioxidant (D) further.

Moreover, the embodiment of the present invention is the pressure-sensitive adhesive further comprising an antistatic agent (E).

Moreover, the embodiment of this invention is a pressure sensitive adhesive sheet provided with the base material and the adhesion layer which is a hardened | cured material of the said adhesive.

Moreover, the embodiment of this invention is a laminated body provided with the member selected from the group which consists of a transparent conductive film, glass, an acrylic board, a polycarbonate board, and an olefin board, and the said adhesive sheet.

Moreover, the embodiment of this invention is a display apparatus provided with the said laminated body.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive which can form the adhesive layer with high smoothness from which the problem of the peeling line residue was eliminated, an adhesive sheet using the same, and a laminated body can be provided.

Terms will be defined before the description of the present invention. In this specification, the adherend refers to a partner to which an adhesive tape is attached. In the present specification, the molecular weight dispersity is a numerical value obtained by dividing the weight average molecular weight by the number average molecular weight, and is a measure of the molecular weight distribution.
In this specification, the pressure-sensitive adhesive sheet includes a base material and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive of the present invention.
In this specification, “tape”, “film”, and “sheet” have the same meaning.
In the present specification, the main component refers to a component having the largest blending amount among a plurality of blended components.

  In the present specification, unless otherwise specified, “molecular weight” means number average molecular weight (Mn). “Mn” is the number average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC) measurement.

The pressure-sensitive adhesive of the present invention includes a hydroxyl group-containing urethane prepolymer (A) which is a reaction product of the polyisocyanate (b) and the polyol (a), an isocyanate curing agent (B), and the urethane prepolymer (A) The molecular weight dispersity is 1.5 or more and less than 4. Surprisingly, by setting the urethane prepolymer (A) to a relatively narrow molecular weight dispersity, it is possible to reduce high molecular weight components that become aggregates by slight cross-linking, and even a minute defect is not allowed in recent years. The present inventor has found that an adhesive layer suitable for the required level can be formed.
The pressure-sensitive adhesive of the present invention can be used for, for example, a liquid crystal display (LCD) having a flat portion or a curved portion, an organic electroluminescence display (ELD), or a touch panel using such a display. In addition, it can be widely used for surface protection of electronic devices such as mobile phones, smart phones, tablet terminals, computers, etc. equipped with such a display or touch panel.
Further, the adherend material is not limited to glass, and examples of the material can be used for protecting easily damaged materials such as polyolefin, gold, silver, copper, and ITO.
Moreover, as a concrete use, it can use not only for a display but for all members and laminated bodies, such as a window glass, LED, a vehicle, wiring, for example. It can also be used for protection during the manufacturing process of the member, as well as for products after manufacturing. In addition, it cannot be overemphasized that the adhesive of this invention can be used for purposes other than surface protection.

(Hydroxyl-containing urethane prepolymer (A))
The hydroxyl group-containing urethane prepolymer (A) is a reaction product obtained by reacting at least one polyisocyanate (b) with at least one polyol (a). The “reactant” means a reaction product of the polyol (a) and the polyisocyanate (b). The polyisocyanate (b) is preferably a bifunctional isocyanate (b1) (also referred to as diisocyanate) having two isocyanate groups in one molecule. The polyol (a) is preferably a polyol (a1) having two or more hydroxyl groups in one molecule. The isocyanate group (isocyanato group) of the polyisocyanate (b) is used in a molar ratio (NCO / OH ratio) such that it is less than the hydroxyl group of the polyol (a). By doing so, the urethane prepolymer obtained becomes a urethane prepolymer having a hydroxyl group. In the urethane reaction, it is preferable to use a catalyst for promoting the reaction. A solvent can be used in the copolymerization reaction as necessary.
The hydroxyl group-containing urethane prepolymer (A) can be used alone or in combination of two or more.

<Polyol (a)>
The polyol (a) is a compound having two or more hydroxyl groups. The polyol (a) is preferably a polyol such as a polyether polyol, a polyether polyol, a polybutadiene-modified polyol, a polycarbonate polyol or a castor oil polyol, more preferably a polyether polyol, a polyester polyol or a polybutadiene-modified polyol.
The polyol (a) used in the present invention may be used in combination of two or more kinds in order to achieve an appropriate cohesive force and adhesive force of the adhesive layer, but a polyol having two hydroxyl groups and a polyol having three or more hydroxyl groups. It is preferable to use together. Moreover, when using together the polyol which has 3 or more of hydroxyl groups, it is preferable to suppress NCO / OH ratio to 0.80 or less.

  Examples of the polyether polyol include a reaction product obtained by addition polymerization of one or more oxirane compounds using an active hydrogen-containing compound having two or more active hydrogens in one molecule as an initiator.

The active hydrogen-containing compound is preferably a hydroxyl group-containing compound or an amine.
Examples of the hydroxyl group-containing compound include bifunctional active hydrogen-containing compounds such as ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, butylethylpentanediol; glycerin, trimethylolpropane and the like. And a trifunctional active hydrogen-containing compound such as pentaerythritol.
Examples of amines include bifunctional active hydrogen-containing compounds such as N-aminoethylethanolamine, isophoronediamine, and xylylenediamine; trifunctional active hydrogen-containing compounds such as triethanolamine; tetrafunctional activities such as ethylenediamine and aromatic diamine. Hydrogen-containing compounds; pentafunctional active hydrogen-containing compounds such as diethylenetriamine.

  Examples of the oxirane compound include alkylene oxides (AO) such as ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO); tetrahydrofuran (THF).

  The polyether polyol preferably has an alkyleneoxy group derived from an active hydrogen-containing compound in the molecule (this polyol is also referred to as “polyoxyalkylene polyol”). As the hydroxyl group-containing compound constituting the polyoxyalkylene polyol, polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol are preferable, and polypropylene glycol having low crystallinity and easily exhibiting flexibility is particularly preferable.

  The number average molecular weight (Mn) of the polyether polyol is not particularly limited, but is preferably 200 to 6,000, more preferably 400 to 4,000, and more preferably 600 to 4, because transparency and flexibility are easily expressed. 000 is more preferable. By making Mn 200 or more, it is easy to control the reaction during the synthesis of the urethane prepolymer (A). Moreover, it is easy to adjust cohesion force to a urethane prepolymer (A) in the moderate range by making Mn 6,000 or less.

  The polyester polyol is, for example, a compound (esterified product) obtained by esterifying one or more polyol components and one or more acid components, or a compound synthesized by ring-opening polymerization of a lactone (ring-opening polymer). preferable.

  Examples of the lactone include polycaprolactone, poly (β-methyl-γ-valerolactone), and polyvalerolactone.

  The polyol component includes, for example, diethylene glycol, 1,3-butanediol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol in addition to the above active hydrogen-containing compound. 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 1,8-octanediol, 1,9- Nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, hexanetriol and the like can be mentioned.

  Examples of the acid component include succinic acid, methyl succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, and 2-methyl-1,4. -Cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid , Dimer acid, trimer acid and acid anhydrides thereof.

  The number average molecular weight (Mn) of the polyester polyol is preferably from 200 to 8,000, more preferably from 500 to 6,000, further preferably from 500 to 4,000, particularly preferably from 500 to 3,000. By making Mn 200 or more, it is easy to control the reaction during the synthesis of the urethane prepolymer (A). Moreover, it is easy to adjust cohesion force to a urethane prepolymer (A) in the moderate range by making Mn 6,000 or less.

  The polybutadiene-modified polyol has, for example, two or more hydroxyl ends, a 1,2-vinyl moiety, a 1,4-cis moiety, a 1,4-trans moiety, or a structure in which they are hydrogenated. It is a chain or branched polybutadiene.

  The number average molecular weight (Mn) of the polybutadiene-modified polyol is preferably 200 to 6,000, more preferably 500 to 6,000, still more preferably 500 to 4,000, and particularly preferably 500 to 3,000. By making Mn 200 or more, it is easy to control the reaction during the synthesis of the urethane prepolymer (A). Moreover, it is easy to adjust cohesion force to a urethane prepolymer (A) in the moderate range by making Mn 6,000 or less.

  The degree of hydrogenation of the polybutadiene-modified polyol is preferably that all of the double bond sites existing before hydrogenation are hydrogenated, but in the present invention, some double bond sites remain. Also good.

Examples of other polyols other than the above include polycarbonate polyols and castor oil polyols. Other polyols are preferably used in combination with polyether polyols or polyester polyols.
The number average molecular weight (Mn) of other polyols is about 200 to 8,000.

  In addition, since polyol (a) may corrode a to-be-adhered body when it contains acidic functional groups, such as a carboxyl group and a sulfo group, it is preferable to use the polyol which does not have an acidic functional group.

<Polyisocyanate (b)>
As the polyisocyanate (b), for example, known polyisocyanates such as aromatic polyisocyanate, aliphatic polyisocyanate, araliphatic polyisocyanate, and alicyclic polyisocyanate can be used.

  Examples of the aromatic polyisocyanate include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6 -Tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4 ' , 4 "-triphenylmethane triisocyanate and the like.

  Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, And 2,4,4-trimethylhexamethylene diisocyanate.

  Examples of the araliphatic polyisocyanate include ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene. 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, and the like.

  Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, and methyl-2. , 4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylene bis (cyclohexyl isocyanate), 1,4-bis (isocyanate methyl) cyclohexane, 1,4-bis (isocyanate methyl) cyclohexane, etc. Can be mentioned.

  The polyisocyanate is a diisocyanate, but a triisocyanate obtained by modifying the diisocyanate can also be used. Examples of the triisocyanate include trimethylolpropane adducts, burettes, and trimers of the diisocyanate (this trimer includes an isocyanurate ring).

  The polyisocyanate (b) is preferably 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), or the like.

  Polyisocyanate (b) can be used alone or in combination of two or more.

<Catalyst>
As the catalyst, for example, a tertiary amine compound and an organometallic compound are preferable.

  Examples of the tertiary amine compound include triethylamine, triethylenediamine, and 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU).

The organometallic compound is preferably a tin compound or a non-tin compound.
Examples of the tin compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin Examples include acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.
Non-tin compounds include, for example, titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride; lead systems such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate Compounds; iron compounds such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc compounds such as zinc naphthenate and zinc 2-ethylhexanoate A zirconium compound such as zirconium naphthenate;

  The catalyst can be used alone or in combination of two or more.

  The catalyst is preferably used in an amount of 0.01 to 1.0 part by mass with respect to 100 parts by mass in total of the polyisocyanate (b) and the polyol (a).

<Solvent>
In the production of the urethane prepolymer (A), one or more solvents can be used as necessary. Examples of the solvent include ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, and hydrocarbon solvents such as toluene and xylene. Among these, ester solvents, hydrocarbon solvents, and the like are preferable from the viewpoint of the solubility of the urethane prepolymer (a) and the boiling point of the solvent.

<Method for producing urethane prepolymer (A)>
The production method of the urethane prepolymer (A) is not particularly limited, and can be produced by a known polymerization method such as a bulk polymerization method or a solution polymerization method.
The procedure of the manufacturing method is, for example,
(Procedure 1) One or more types of polyisocyanate (b), one or more types of polyol (a), one or more types of catalysts as required, and one or more types of solvents as needed are charged into a flask at once. procedure;
(Procedure 2) One or more types of polyol (a), one or more types of catalysts as required, and one or more types of solvents as required are charged into a flask, and one or more types of polyisocyanate (b) is added thereto. The procedure of adding dropwise is mentioned.
Among these, (Procedure 2) is preferable because low molecular components in the raw material are preferentially reacted to narrow the molecular weight dispersity and the reaction control is easy.

  When using a catalyst, the reaction temperature is preferably less than 100 ° C, more preferably 85 to 95 ° C. When the reaction temperature is less than 100 ° C., side reactions other than the urethane reaction can be suppressed, so that a desired resin can be easily obtained. When no catalyst is used, the reaction temperature is preferably 100 ° C or higher, more preferably 110 ° C or higher.

  When the urethane prepolymer (a) is produced, the isocyanate group (NCO) of the polyisocyanate (b) and the hydroxyl group (OH) of the polyol (y) are 0.3 to 0.95 in terms of a molar ratio of NCO / OH. Is preferred, 0.4 to 0.90 is more preferred, and 0.5 to 0.80 is even more preferred. Since the urethane prepolymer having an appropriate molecular chain can be formed when the NCO / OH ratio is within the above range, wettability and productivity are further improved.

  When using a catalyst in the synthesis, it is preferable to deactivate the catalyst. As the reaction terminator, for example, acetylacetone may be blended.

  The reaction terminator can be used alone or in combination of two or more.

  The weight average molecular weight (Mw) of the urethane prepolymer (A) is preferably 10,000 to 200,000, more preferably 30,000 to 180,000, and still more preferably 30,000 to 150,000. When the weight average molecular weight (Mw) is within the above range, the generation of high molecular weight components can be suppressed, and the coating film smoothness can be ensured.

  The lower limit of the molecular weight dispersity of the urethane prepolymer (A) is 1.5 or more, preferably 1.8 or more, and more preferably 2.0 or more. Moreover, an upper limit is less than 4, 3.6 or less are preferable and 3 or less are more preferable. Surprisingly, by setting the molecular weight dispersity of the urethane prepolymer (A) within the above range, it is possible to obtain a pressure-sensitive adhesive capable of forming a high-smooth pressure-sensitive adhesive layer in which the problem of remaining peeling lines has been solved. The inventor has found that this is possible.

(Isocyanate curing agent (B))
The isocyanate curing agent (B) is a known compound having a plurality of isocyanate groups. The isocyanate curing agent (B) is preferably the polyisocyanate (b), among which aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates, and trimethylolpropane adducts thereof. , And these burette bodies, and trifunctional isocyanates that are these trimers are more preferable.

  The isocyanate curing agent (B) can be used alone or in combination of two or more.

  The blending amount of the isocyanate curing agent (B) is preferably from 0.1 to 30 parts by mass, more preferably from 1 to 25 parts by mass, and from 3 to 20 parts by mass with respect to 100 parts by mass of the urethane prepolymer (A). Is more preferable, and 5 to 15 parts by mass is particularly preferable. When an appropriate amount of the isocyanate curing agent (B) is blended, moderate adhesive strength, cohesive strength and peel resistance are easily obtained.

(Plasticizer (C))
The pressure-sensitive adhesive of the present invention can further contain a plasticizer (C). By including a plasticizer (C), the wettability of the adhesion layer with respect to a to-be-adhered body improves more. The plasticizer (C) is preferably a fatty acid ester or phosphate ester having 8 to 30 carbon atoms from the viewpoint of compatibility with other components.

  The fatty acid ester having 8 to 30 carbon atoms is, for example, an ester of a monobasic acid or polybasic acid having 6 to 18 carbon atoms and a branched alcohol having 18 or less carbon atoms, an unsaturated fatty acid having 14 to 18 carbon atoms or a branched acid. Examples include esters with tetravalent or lower alcohols, esters of monobasic acids or polybasic acids with 6 to 18 carbon atoms and polyalkylene glycols, fatty acid esters obtained by epoxidizing unsaturated sites with peroxides, and the like.

  Examples of the ester of a monobasic acid or polybasic acid having 6 to 18 carbon atoms and a branched alcohol having 18 or less carbon atoms include isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isopentyl palmitate Examples include stearyl, isocetyl stearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimerate, and triisocetyl trimerate.

  The unsaturated fatty acid of 14 to 18 carbon atoms and the branched acid and the tetrahydric or less alcohol constituting an ester of an unsaturated fatty acid or a branched acid and a tetrahydric or less alcohol having 14 to 18 carbon atoms are as follows. Examples of the unsaturated fatty acid or branched acid having 14 to 18 carbon atoms include myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, and isostearic acid. Examples of the tetrahydric or lower alcohol include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitan and the like.

  Examples of the ester of monobasic acid or polybasic acid having 6 to 18 carbon atoms and polyalkylene glycol include polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurate, polyethylene glycol dioleate, and adipic acid Examples include dipolyethylene glycol methyl ether.

  Fatty acid esters obtained by epoxidizing unsaturated sites with peroxides, for example, epoxidized epoxidized fats and oils such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized cottonseed oil, and unsaturated fatty acids having 8 to 18 carbon atoms Examples thereof include ester compounds of a compound and a linear or branched alcohol having 1 to 6 carbon atoms.

  Examples of the phosphoric acid ester include phosphoric acid or an ester compound of phosphoric acid and a linear or branched alcohol having 2 to 18 carbon atoms.

  The plasticizer (C) can be used alone or in combination of two or more.

  The number average molecular weight (Mn) of the plasticizer (C) is preferably 300 to 1000, more preferably 300 to 900, and still more preferably 350 to 850, from the viewpoint of improving the wetting rate.

  0.1-100 mass parts is preferable with respect to 100 mass parts of urethane prepolymers (A), as for the compounding quantity of a plasticizer (C), 1-80 mass parts is more preferable, and 10-50 mass parts is more preferable. When an appropriate amount of the plasticizer (C) is blended, the wettability is further improved.

(Antioxidant (D))
The pressure-sensitive adhesive of the present invention can further contain an antioxidant (D). When the antioxidant (D) is contained, the thermal deterioration of the urethane prepolymer (A) can be suppressed.
The antioxidant is preferably a radical chain inhibitor such as a phenol-based antioxidant and an amine-based antioxidant, and a sulfur-based antioxidant or a phosphorus-based antioxidant. A phenolic antioxidant is more preferred.

Examples of phenolic antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and stearin-β- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate and other monophenolic antioxidants;
2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-t) -Butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), and 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy) Bisphenol antioxidants such as -5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane;
1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl) -4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis- (4'-Hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, and 1,3,5-tris (3 ', 5'-di-t-butyl-4'-hydroxybenzyl) -S-triazine- Examples thereof include polymeric phenolic antioxidants such as 2,4,6- (1H, 3H, 5H) trione and tocophenol.

  Examples of the sulfur-based antioxidant include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and distearyl 3,3'-thiodipropionate.

  Examples of the phosphorus antioxidant include triphenyl phosphite, diphenylisodecyl phosphite, and phenyl diisodecyl phosphite.

  The antioxidant (D) can be used alone or in combination of two or more.

    0.01-10 mass parts is preferable with respect to 100 mass parts of urethane prepolymers (A), and, as for the compounding quantity of antioxidant (D), 0.1-5 mass parts is more preferable.

(Antistatic agent (E))
The pressure-sensitive adhesive of the present invention can further contain an antistatic agent (E). When the antistatic agent (E) is contained, electrostatic discharge when the pressure-sensitive adhesive sheet is peeled off is suppressed, and for example, damage to components incorporated in a display or the like is easily prevented.
Examples of the antistatic agent include inorganic salts, ionic liquids, surfactants, and the like. Among these, an ionic liquid is preferable. The “ionic liquid” is also called a room temperature molten salt, and exhibits liquid properties at 25 ° C.

  Inorganic salts include, for example, sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, ammonium sulfate, potassium nitrate, sodium nitrate, Examples thereof include sodium carbonate and sodium thiocyanate.

  The ionic liquid is a salt of a cation and an anion, and the cation is preferably, for example, an imidazolium ion, a pyridinium ion, or an ammonium ion.

    Ionic liquids containing imidazolium ions include, for example, 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1,3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide, and 1-butyl- Examples include 3-methylimidazolium bis (trifluoromethylsulfonyl) imide.

  Examples of ionic liquids containing pyridinium ions include 1-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-butylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexylpyridinium bis (trifluoromethylsulfonyl) imide, -Octylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4-methyl Pyridinium bis (trifluoromethylsulfonyl) imide, 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide, 1-methylpyridinium bis (perfluoroethylsulfonyl) imi , And 1-methyl-pyridinium bis (perfluorobutylsulfonyl) imide, and the like.

  Examples of the ionic liquid containing ammonium ion include trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-propylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N. -Methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, and tri-n-butylmethylammonium bistrifluoromethanesulfonimide Etc.

  In addition, known ionic liquids whose cations are pyrrolidinium salts, phosphonium salts, sulfonium salts, and the like can be used as appropriate.

  Surfactants can be classified into nonionic, anionic, cationic, and amphoteric types.

Nonionic types include, for example, glycerin fatty acid ester, polyoxyalkylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamine fatty acid ester, fatty acid diethanolamide, polyetheresteramide type , Ethylene oxide-epichlorohydrin type, and polyether ester type.
Examples of the anionic type include alkyl sulfonate, alkyl benzene sulfonate, alkyl phosphate, and polystyrene sulfonate type.
Examples of the cationic type include tetraalkylammonium salts, trialkylbenzylammonium salts, and quaternary ammonium base-containing acrylate polymer types.
Examples of amphoteric types include amino acid-type amphoteric surfactants such as alkylbetaines and alkylimidazolium betaines, higher alkylaminopropionates, and betaine-type amphoteric surfactants such as higher alkyldimethylbetaines and higher alkyldihydroxyethylbetaines. Is mentioned.

  The antistatic agent (E) can be used alone or in combination of two or more.

  0.01-10 mass parts is preferable with respect to 100 mass parts of urethane prepolymers (A), and, as for the compounding quantity of an antistatic agent (E), 0.03-5 mass parts is more preferable.

(Polyfunctional polyol (F))
In the present invention, the polyfunctional polyol (F) reacts with the isocyanate curing agent (B) together with the urethane prepolymer (A) to form a segment having a high crosslinking density in the crosslinked structure of the pressure-sensitive adhesive layer. This segment with a high crosslink density is excellent in surface orientation due to the low molecular weight immediately before the reaction, and has the effect of strengthening the coating surface and reducing the remaining peeling line.

  As the polyfunctional polyol (F), among the already described polyols (a), a polyol having 3 or more hydroxyl groups in one molecule and having a primary hydroxyl group at the molecular end can be used.

  The number of hydroxyl groups in one molecule of the polyfunctional polyol (F) is 3 or more. By setting the number of hydroxyl groups in one molecule to 3 or more, a segment having a high crosslinking density can be appropriately adjusted on the surface of the coating film, so that the peeling line residue is further reduced.

  The polyfunctional polyol (F) has a primary hydroxyl group at the molecular end. When the hydroxyl group at the molecular end is primary, the reaction with the curing agent is given priority over the urethane prepolymer (A), and the coating smoothness is deteriorated due to the reaction between the high molecular weight component of the urethane prepolymer (A) and the curing agent. Can be suppressed.

  It is preferable that 2-50 mass parts is contained with respect to 100 mass parts of urethane prepolymers (A), and, as for polyfunctional polyol (F), 5-30 mass parts is more preferable. By including 2 to 50 parts by mass of the polyfunctional polyol (F), the ratio of segments having a high crosslinking density can be appropriately adjusted on the coating film surface, so that the peeling line residue is further reduced.

  As the polyfunctional polyol (F), among the polyols (a) listed above, those having 3 or more hydroxyl groups in one molecule and having a primary hydroxyl group at the molecular end can be used. Polyester polyol or polyether polyol is particularly preferable.

  The number average molecular weight (Mn) of the polyfunctional polyol (F) is preferably in the range of 500 to 6,000, more preferably 1,000 to 5,000. If it is 500 or more, the production | generation of the microgel which reacted with the isocyanate hardening | curing agent (B) locally can be suppressed, and if it is 6,000 or less, the peeling line remainder can be suppressed by making the molecular weight between bridge | crosslinking small.

(solvent)
As the solvent, a solvent that can be used in the production of the urethane prepolymer (A) can be used, and ester solvents, hydrocarbon solvents, and the like are preferable. The solvent can be used alone or in combination of two or more.

(Optional component)
The pressure-sensitive adhesive of the present invention can contain an optional component, if necessary, within a range that can solve the problem. Optional components are resin, filler, metal powder, pigment, foil, softener, UV absorber, light stabilizer, surface lubricant, leveling agent, corrosion inhibitor, heat stabilizer, polymerization inhibitor, antifoam Agents, lubricants and the like.

  Examples of the filler include talc, calcium carbonate, titanium oxide and the like.

  Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, salicylic acid UV absorbers, oxalic anilide UV absorbers, cyanoacrylate UV absorbers, and triazine UV absorbers. It is done.

  Examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2′- Dihydroxy-4-dimethoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, and bis (2-methoxy-4-hydroxy-5-benzoylphenyl) ) Methane and the like.

  Examples of the benzotriazole-based ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2 '-Hydroxy-3', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) 5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2 -(2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2- [2'-hydroxy-3 '-(3' ', '', 5 '', 6 '',-tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2,2'methylenebis [4- (1,1,3,3-tetramethylbutyl) -6 (2H-benzotriazol-2-yl) phenol], [2 (2′-hydroxy-5′-methacryloxyphenyl) -2H-benzotriazole, and the like.

  Examples of the salicylic acid ultraviolet absorber include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate.

  Examples of the cyanoacrylate ultraviolet absorber include 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate and ethyl-2-cyano-3,3'-diphenyl acrylate.

  Examples of the light stabilizer include a hindered amine light stabilizer and an ultraviolet light stabilizer.

  Examples of the hindered amine light stabilizer include [bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate], bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, And methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate and the like.

  Examples of the UV stabilizer include nickel bis (octylphenyl) sulfide, [2,2′-thiobis (4-tert-octylphenolate)]-n-butylamine nickel, nickel complex-3,5-di-tert-butyl. Examples include -4-hydroxybenzyl-phosphate monoethylate, nickel-dibutyldithiocarbamate, benzoate type quencher, and nickel-dibutyldithiocarbamate.

  Examples of the leveling agent include an acrylic leveling agent, a fluorine leveling agent, and a silicon leveling agent. A commercially available leveling agent includes acrylic leveling agents such as Polyflow No. 36, Polyflow No. 56, Polyflow No. 85HF, Polyflow No. 99C (Isure is also Kyoeisha Chemical Co., Ltd.). Examples of the fluorine leveling agent include Megafac F470N and Megafac F556 (both manufactured by DIC). Examples of the silicon leveling agent include Grandic PC4100 (manufactured by DIC).

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention includes a base material and a pressure-sensitive adhesive layer that is a cured product of the pressure-sensitive adhesive. The adhesive layer can be formed on one side or both sides of the substrate. The surface of the adhesive layer that is not in contact with the base material is usually protected with a release sheet until just before use in order to prevent the adhesion of foreign substances.

As the base material, a flexible sheet and plate material can be used without limitation. Examples of the substrate include plastic, paper, metal foil, and a laminate thereof.
In order to improve adhesion, the surface of the substrate that contacts the adhesive layer can be subjected in advance to an easy adhesion process such as a dry process such as a corona discharge process or a wet process such as application of an anchor coat agent.

  Examples of the base plastic include ester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); olefin resins such as polyethylene (PE), polypropylene (PP) and cycloolefin polymer (COP); Vinyl resins such as vinyl; amide resins such as nylon 66; urethane resins (including foams); and the like.

  The thickness of the substrate is usually about 10 to 300 μm. Moreover, the thickness in the case of using a polyurethane sheet (a foam is included) for a base material is about 20-50,000 micrometers normally. Examples of the paper include plain paper, coated paper, and art paper. Examples of the metal foil include aluminum foil and copper foil.

  As the release sheet, a known release sheet in which a known release treatment such as a silicone-based release agent is performed on the surface of plastic or paper can be used.

  Examples of the method for producing a pressure-sensitive adhesive sheet include a method in which a pressure-sensitive adhesive is applied to the surface of a substrate to form a coating layer, and then the coating layer is dried and cured to form a pressure-sensitive adhesive layer. The heating and drying temperature is usually about 60 to 150 ° C. The thickness of the pressure-sensitive adhesive layer is usually about 0.1 to 200 μm.

  Examples of the coating method include known methods such as a roll coater method, a comma coater method, a die coater method, a reverse coater method, a silk screen method, and a gravure coater method.

  In contrast to the above method, a pressure-sensitive adhesive layer is formed by applying a pressure-sensitive adhesive to the surface of the release sheet to form a coating layer, and then drying and curing the coating layer. Is formed, and finally the substrate is bonded to the exposed surface of the adhesive layer. When a release sheet is bonded in place of the substrate by the above method, a cast adhesive sheet of release sheet / adhesive layer / release sheet is obtained.

  Hereinafter, embodiments of the present invention will be described by way of examples. In addition, it cannot be overemphasized that the embodiment of this invention is not limited to an Example. Hereinafter, “part” means “part by mass”, and “%” means “% by mass”.

[Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)]
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) method. The measurement conditions are as follows. Mw and Mn are both polystyrene equivalent values.
<Measurement conditions>
Apparatus: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: Three SHODEX LF-804 (Showa Denko) are connected in series.
Detector: Differential refractive index detector Solvent: Tetrahydrofuran (THF)
Flow rate: 0.5 mL / min Solvent temperature: 40 ° C
Sample concentration: 0.1%
Sample injection volume: 100 μL

[material]
The materials used are as follows.
<Polyol (a)>
(A1): P510 ("Kuraray polyol P-510", polyester polyol, Mn500, hydroxyl number 2, primary hydroxyl group, manufactured by Kuraray Co., Ltd.)
(A2): P1010 ("Kuraray polyol P-1010", polyester polyol, Mn1000, hydroxyl number 2, primary hydroxyl group, manufactured by Kuraray Co., Ltd.)
(A3): P2010 ("Kuraray polyol P-2010", polyester polyol, Mn2000, hydroxyl number 2, primary hydroxyl group, manufactured by Kuraray Co., Ltd.)
(A4): P3199 ("Preplast 3199", polyester polyol, Mn2000, hydroxyl number 2, primary hydroxyl group, manufactured by CRODA)
(A5): PP1000 ("Sanix PP-1000", polyoxypropylene glycol, Mn1000, hydroxyl number 2, secondary hydroxyl group, manufactured by Sanyo Chemical Industries)
(A6): PP2000 (“Sanniks PP-2000”, polyoxypropylene glycol, Mn2000, hydroxyl number 2, secondary hydroxyl group, manufactured by Sanyo Chemical Industries)
(A7): PP4000 (“SANNICS PP-4000”, polyoxypropylene glycol, Mn4000, hydroxyl number 2, secondary hydroxyl group, manufactured by Sanyo Chemical Industries)
(A8): GI1000 (“NISSO-PB GI-1000”, hydroxylated at both ends, polybutadiene, Mn1,500, hydroxyl number 2, primary hydroxyl group, manufactured by Nippon Soda Co., Ltd.)
(A9): GI3000 ("NISSO-PB GI-3000", hydroxylated at both ends, polybutadiene, Mn3100, hydroxyl number 2, primary hydroxyl group, manufactured by Nippon Soda Co., Ltd.)
(A10): HLBH P2000 (“Krasol (registered trademark) HLBPH P200000”, terminal hydroxyl group-modified liquid polybutadiene, Mn2000, hydroxyl number 1.95, primary hydroxyl group, manufactured by CRAY VALLEY)
(A11): F3010 ("Kuraray polyol F-3010", polyester polyol, Mn 3000, hydroxyl number 3, primary hydroxyl group, manufactured by Kuraray Co., Ltd.)
(A12): AM302 (“Adeka Polyether AM-302”, glycerin PO / EO polyol, Mn 3000, hydroxyl number 3, primary hydroxyl group, manufactured by ADEKA)
(A13): R45HTLO ("Poly bd (registered trademark) R45HTLO", terminal hydroxyl group-modified liquid polybutadiene, Mn2800, hydroxyl number 3, primary hydroxyl group, manufactured by CRAY VALLEY)
(A14): GP3000 ("Sanniks GP-3000", glycerin / polyoxypropylene glycol, Mn3000, hydroxyl number 3, secondary hydroxyl group, manufactured by Sanyo Chemical Industries)

<Polyisocyanate (b)>
(B1): HDI (hexamethylene diisocyanate, “Desmodur H” manufactured by Sumika Covestrourethane Co., Ltd.),
(B2): IPDI (isophorone diisocyanate, “Desmodur I” manufactured by Sumika Covestrourethane Co., Ltd.)
(B3): TDI (tolylene diisocyanate, “Coronate T-65” manufactured by Tosoh Corporation).

<Isocyanate curing agent (B)>
(B1): HDI adduct (“Sumijour HT”, trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Sumika Covestro Urethane Co., Ltd.)
(B2): HDI nurate (“Sumijour N3300”, nurate of hexamethylene diisocyanate, manufactured by Sumika Covestro Urethane Co., Ltd.)
(B3): HDI biuret (“Sumijour N3200”, hexamethylene diisocyanate burette body, manufactured by Sumika Covestro Urethane Co., Ltd.)

<Polyfunctional polyol (F)>
The same thing as said (a11)-(a13) is used as polyfunctional polyol (F1)-(F3), respectively.
<Polyfunctional polyol (F ') which is not polyfunctional polyol (F)>
The same thing as said (a14) is used as a polyfunctional polyol (F4).
<Plasticizer (C)>
(C1): M182A (“Unistar M182A”, methyl oleate, manufactured by NOF Corporation)
(C2): W262 ("Monocizer W262", ether ester plasticizer, manufactured by DIC Corporation)
(C3): D55 (“Adekasizer D-55”, epoxidized fatty acid alkyl ester, manufactured by ADEKA)
(C4): TOP (“TOP”, tris (2-ethylhexyl) phosphate, manufactured by Daihachi Industrial Chemical Co., Ltd.)

<Antioxidant (D)>
(D1): Irg1010 (“Irganox 1010”, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], phenolic antioxidant, manufactured by BASF)

<Antistatic agent (E)>
(E1): FSI-ammonium salt (tri-n-butylmethylammonium bistrifluoromethanesulfonimide)
(E2): FSI-lithium salt (lithium bistrifluoromethanesulfonimide)

[Synthesis Example of Urethane Prepolymer (A)]
(Synthesis Example 1)
In a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 1000 parts of Kuraray polyol P-510 (bifunctional polyester polyol, manufactured by Kuraray Co., Ltd.), 300 parts of hexamethylene diisocyanate, 557 parts of toluene Then, 0.1 part of dioctyltin dilaurate was charged as a catalyst, the temperature was gradually raised to 100 ° C., and the reaction was performed for 2 hours. After confirming the disappearance of NCO characteristic absorption (2,270 cm ⁻¹ ) in the IR chart, the reaction was completed after cooling to 25 ° C. and adding 13 parts of acetylacetone. The urethane prepolymer (A1) had an Mw of 31,000 and a molecular weight dispersity of 1.8.

(Synthesis Examples 2 to 23)
The urethane prepolymer (A) of Synthesis Examples 2 to 22 and the urethane of Synthesis Example 23 were performed in the same manner as in Synthesis Example 1 except that the materials and blending ratios of Example 1 were changed as shown in Table 1. A urethane prepolymer (A ′) that was not the prepolymer (A) was obtained. Table 1 shows the Mw and molecular weight dispersibility of the obtained urethane prepolymer (A) and urethane prepolymer (A '). In addition, the compounding quantity of the raw material in a table | surface is conversion of a non volatile matter, and the unit of the numerical value without a notice in particular is [part].

Example 1
100 parts of urethane prepolymer (A1) obtained in Synthesis Example 1, 10 parts of isocyanate curing agent (B1), 0.5 part of antioxidant (D1), 10 parts of polyfunctional polyol (F1 = a11), and solvent 100 parts of ethyl acetate was blended and stirred with a disper to obtain an adhesive. In addition, the usage-amount of each material except a solvent shows a non-volatile content conversion value [part].

Polyethylene terephthalate (PET) (“Lumirror T-60”, manufactured by Toray Industries, Inc.) having a thickness of 50 μm was prepared as a base material. Using a comma coater (registered trademark), the obtained pressure-sensitive adhesive is applied on the above-mentioned base material at a coating speed of 3 m / min, a width of 30 cm and a thickness of 12 μm after drying to form a coating layer. did.
Next, the formed coating layer was dried at 100 ° C. for 1 minute using a drying oven to form an adhesive layer. A commercially available release sheet having a thickness of 38 μm was bonded onto the adhesive layer, and the adhesive sheet was obtained by curing for 1 week under the condition of 23 ° C.-50% RH.

(Examples 2-42, Comparative Examples 1-3)
Except having changed the material and compounding ratio of Example 1 as shown in Tables 2-4, it carries out similarly to Example 1, respectively, The adhesive and adhesive sheet of Examples 2-42 and Comparative Examples 1-3 are respectively obtained. Obtained.

[Evaluation items and methods]
Evaluation items and evaluation methods of the obtained pressure-sensitive adhesive and pressure-sensitive adhesive sheet are as follows.

(Peeling resistance)
The obtained pressure-sensitive adhesive tape was prepared to have a width of 50 mm and a length of 100 mm and used as a measurement sample. Next, the release liner was peeled off in an atmosphere of 23 ° C. and 50% RH, the exposed adhesive layer was attached to a glass plate, and a 2 kg roll was reciprocated once to make a laminate. After 1 minute, when the half of the bonded area was peeled off, the peeling was temporarily interrupted, and the adhesive tape was completely peeled off after standing for 10 seconds in that state. The remaining state of the line of the adhesive layer (the trace generated when the peeling was interrupted) caused by stopping the peeling in the middle was visually evaluated through the light of light in the dark room. The evaluation criteria are as follows.
A: The line is not completely visible. Excellent.
○: A part of the line is visible. Good.
Δ: The entire line is slightly visible. Can be used practically.
X: The line is clearly visible. Not practical.

(Coating smoothness)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the coating speed in Example 1 was changed to 30 m / min and the width was changed to 150 cm, and the number of defects in high-speed coating was evaluated. In the evaluation, the number of aggregates (number of defects) having a size visually recognized was evaluated per 1 m ² .
A: 0 pieces. Excellent.
○: 1 piece. Good.
Δ: 1 to 3 Can be used practically.
X: 4 or more. Not practical.

Claims (9)

A hydroxyl group-containing urethane prepolymer (A) which is a reaction product of the polyol (a) and the polyisocyanate (b), an isocyanate curing agent (B) and a polyfunctional polyol (F),
The urethane prepolymer (A) has a molecular weight dispersity of 1.5 or more and less than 4,
The polyfunctional polyol (F) is a pressure-sensitive adhesive having 3 or more hydroxyl groups in one molecule and having a primary hydroxyl group at the molecular end.   The pressure-sensitive adhesive according to claim 1, wherein the polyol (a) includes one or more selected from the group consisting of a polyether polyol, a polyester polyol, and a polybutadiene-modified polyol.   The pressure-sensitive adhesive according to claim 1 or 2, comprising 2 to 50 parts by mass of the polyfunctional polyol (F) with respect to 100 parts by mass of the urethane prepolymer (A).   Furthermore, the adhesive of any one of Claims 1-3 containing a plasticizer (C).   Furthermore, the adhesive of any one of Claims 1-4 containing antioxidant (D).   Furthermore, the adhesive of any one of Claims 1-5 containing an antistatic agent (E).   The adhesive sheet provided with the adhesive layer which is a base material and the hardened | cured material of the adhesive of any one of Claims 1-5.   The laminated body provided with the member selected from the group which consists of a transparent conductive film, glass, an acrylic board, a polycarbonate board, and an olefin board, and the adhesive sheet of Claim 7.   A display device comprising the laminate according to claim 8.