JP2020033536A - Urethane-based pressure-sensitive adhesive and pressure-sensitive adhesive sheet - Google Patents

Abstract

To provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer that ensures reduction in adhesive power and favorable removability both during an initial period (prior to passing of time) and after passing of time (in particular, after a (wet) heated time period), and that leaves little taint on an adherend after being removed.SOLUTION: The pressure-sensitive adhesive according to the present invention is a urethane-based pressure-sensitive adhesive comprising: at least one type of active hydrogen group-containing compound (H) having a plurality of active hydrogen groups in each molecule; at least one type of polyfunctional isocyanate compound (I); and at least one type of surfactant (S) having a cationic hydrophilic group, where the surfactant (S) has an amine value of 0.1-160 mgKOH/g in terms of nonvolatile components, and the content of the surfactant (S) is 0.01-20 pts.mass based on 100 pts.mass of the active hydrogen group-containing compound (H).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a urethane-based pressure-sensitive adhesive and a pressure-sensitive adhesive sheet.

BACKGROUND ART Conventionally, pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer formed on a base sheet have been widely used as surface protection sheets for various members. Examples of the adhesive include an acrylic adhesive, a silicone adhesive, and a urethane adhesive. Acrylic pressure-sensitive adhesives have excellent adhesive strength, but are poor in removability after being adhered to an adherend because of their strong adhesive strength. In particular, after aging in a (moisture) heat environment, the re-peelability is further reduced due to the increase in the adhesive strength, and the adherend tends to be liable to be caused to remain on the surface of the adherend after re-peeling. is there. Silicone-based pressure-sensitive adhesives are liable to cause contamination on adherends, and furthermore, silicone resin having a relatively low molecular weight may be volatilized and adsorbed on the surface of equipment such as electronic devices to cause problems. On the other hand, the urethane-based pressure-sensitive adhesive has good adhesion to the adherend, relatively excellent removability, and is unlikely to volatilize.
In the present specification, the “adhesive” is an adhesive having removability (removable adhesive), and the “adhesive sheet” is an adhesive sheet having removability (removable adhesive sheet).

Flat panel displays such as liquid crystal displays (LCD) and organic electroluminescent displays (OELD), and touch panel displays combining such flat panel displays and touch panels are used in televisions (TVs), personal computers (PCs), mobile phones, Widely used for electronic devices such as portable information terminals.
Urethane-based pressure-sensitive adhesive sheets include flat panel displays and touch panel displays, and substrates (glass substrates and ITO / glass substrates having an ITO (indium tin oxide) film formed on the glass substrates) manufactured or used in these manufacturing processes. Etc.) and surface protection sheets for optical members and the like.

  As a method for producing a urethane-based pressure-sensitive adhesive, a method using a hydroxyl-terminated urethane prepolymer and a polyfunctional isocyanate compound which are reaction products of an active hydrogen group-containing compound such as a polyol and a polyisocyanate, and a method using a hydroxyl-terminated urethane prepolymer And a method in which an active hydrogen group-containing compound such as a polyol is reacted with a polyfunctional isocyanate compound at once (one-shot method).

  A general method for producing a pressure-sensitive adhesive sheet includes a coating step of coating a pressure-sensitive adhesive on a base sheet, and a heat-drying treatment of the formed coating layer to form a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive. The method includes a heating step, a winding step of winding the obtained pressure-sensitive adhesive sheet around a core to form a pressure-sensitive adhesive sheet roll, and a curing step of curing the pressure-sensitive adhesive sheet roll.

JP 2014-162821 A JP 2018-0626228 A JP 2015-172202 A JP 2011-037928 A

Urethane-based pressure-sensitive adhesives cure immediately after production, but if the initial curability is low, the coating layer or pressure-sensitive adhesive layer may be heated with hot air during heating and drying of the coating layer, or the pressure-sensitive adhesive sheet obtained after heating and drying. There is a possibility that the surface of the pressure-sensitive adhesive layer may have poor surface appearance such as a core step mark, citron skin, curl and the like due to the influence of mechanical stress applied during curing. The urethane-based pressure-sensitive adhesive preferably has a good pot life and a good initial curability.

  The pressure-sensitive adhesive sheet has good removability that can be easily re-peeled from the adherend when it is detached from the adherend, both initially (before aging) and after aging (especially after (wet) heat aging). Is preferred. Conventionally, in general, when the pressure-sensitive adhesive sheet is exposed to a (moist) heat environment, the anchoring property between the adherend and the pressure-sensitive adhesive layer is increased, so that the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer is increased and the removability is reduced. Tends to decrease. The pressure-sensitive adhesive sheet preferably has good removability even when exposed to a (moist) heat environment, and preferably has no adherend contamination in which the pressure-sensitive adhesive component remains on the surface of the adherend after re-peeling.

  Although details will be described later, Patent Documents 1 to 4 are mentioned as related documents of the present invention.

  The present invention has been made in view of the above circumstances, has good initial curability, and has a reduced adhesive strength at both the initial stage (before aging) and after aging (especially after (wet) heat aging), and has good It is an object of the present invention to provide a pressure-sensitive adhesive having excellent removability and capable of forming a pressure-sensitive adhesive layer with little adherend contamination after re-peeling, and a pressure-sensitive adhesive sheet using the same.

The pressure-sensitive adhesive of the present invention,
One or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups in one molecule,
One or more polyfunctional isocyanate compounds (I),
And one or more surfactants (S) having a cationic hydrophilic group,
The surfactant (S) has an amine value of 0.1 to 160 mgKOH / g in terms of nonvolatile components,
A urethane-based pressure-sensitive adhesive having a surfactant (S) content of 0.01 to 20 parts by mass with respect to 100 parts by mass of the active hydrogen group-containing compound (H).

  The pressure-sensitive adhesive sheet of the present invention includes a base sheet and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive of the present invention.

  In the present specification, “Mw” is a weight average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC). “Mn” is the number average molecular weight in terms of polystyrene determined by GPC measurement. These can be measured by the method described in [Example].

  According to the present invention, the initial curability is good, the adhesive force is reduced in both the initial stage (before aging) and after aging (particularly after (wet) heat aging), and the film has good removability. An adhesive capable of forming an adhesive layer with less contamination of an adherend after re-peeling, and an adhesive sheet using the same can be provided.

It is a schematic cross section of the pressure sensitive adhesive sheet of a 1st embodiment concerning the present invention. It is a schematic cross section of an adhesive sheet of a second embodiment according to the present invention.

[Urethane adhesive]
The pressure-sensitive adhesive of the present invention,
At least one active hydrogen group-containing compound (H) having a plurality of active hydrogen groups in one molecule, at least one polyfunctional isocyanate compound (I), and at least one surfactant having a cationic hydrophilic group A urethane-based pressure-sensitive adhesive containing an agent (S).
In the pressure-sensitive adhesive of the present invention, the surfactant (S) has an amine value of 0.1 to 160 mgKOH / g in terms of non-volatile components, and the surfactant (S) is used in an amount of 100 parts by mass of the active hydrogen group-containing compound (H). The content is 0.01 to 20 parts by mass.
The pressure-sensitive adhesive sheet of the present invention is a urethane-based pressure-sensitive adhesive sheet including a base sheet and a pressure-sensitive adhesive layer formed of a cured product of the pressure-sensitive adhesive of the present invention.

The active hydrogen group-containing compound (H) is a compound having a plurality of active hydrogen groups in one molecule.
Examples of the active hydrogen group include a hydroxyl group (hydroxy group), a mercapto group, and an amino group (an amino group includes an imino group unless otherwise specified in this specification). Examples of the active hydrogen group-containing compound (H) include a polyol having a plurality of hydroxyl groups in one molecule, a polyamine having a plurality of amino groups in one molecule, an amino alcohol having an amino group and a hydroxyl group in one molecule, and one molecule Examples thereof include polythiols having a plurality of mercapto groups. These active hydrogen group-containing compounds (H) may be non-polymers or polymers. These can be used alone or in combination of two or more.
Among them, polyol is preferable. Since polyamines and polythiols have high reactivity and short pot life, they are preferably used in combination with polyols. Further, when the active hydrogen group of the polyol is a secondary hydroxyl group, the initial curability of the urethane-based pressure-sensitive adhesive does not improve, so that from the viewpoint of pot life and initial curability, the polyol has a primary hydroxyl group having an appropriate reactivity. It is preferred to include.

(Hydroxy-terminated urethane prepolymer (UPH))
Examples of the active hydrogen group-containing compound (H) include a hydroxyl-terminal urethane which is a reaction product obtained by copolymerizing one or more active hydrogen group-containing compounds (HX) and one or more polyisocyanates (N). Prepolymers (UPH) are preferred. The copolymerization reaction can be carried out in the presence of one or more catalysts, if necessary. One or more solvents can be used in the copolymerization reaction, if necessary.

<Active hydrogen group-containing compound (HX)>
Examples of the polyol that can be used as the active hydrogen group-containing compound (HX) include polyester polyol, polyether polyol, polyacryl polyol, polycaprolactone polyol, polycarbonate polyol, and castor oil-based polyol. Among them, polyester polyols, polyether polyols, and combinations thereof are preferred.

  Known polyester polyols can be used as the active hydrogen group-containing compound (HX). Examples of the polyester polyol include a compound (esterified product) obtained by an esterification reaction between one or more polyol components and one or more acid components.

  Examples of the raw material polyol component include ethylene glycol (EG), propylene glycol (PG), diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-ethyl-1,3- Hexanediol (1,3-octanediol), 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylol And propane, pentaerythritol, hexanetriol and the like.

  The acid components of the raw materials include succinic acid, methyl succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecandioic acid, 1,14-tetradecandioic acid, dimer acid, 2-methyl-1, 4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, and anhydrides thereof And the like.

  Known polyether polyols that can be used as the active hydrogen group-containing compound (HX) can be used. Examples of the polyether polyol include a compound (addition polymer) obtained by addition-polymerizing one or more oxirane compounds using an active hydrogen group-containing compound having a plurality of active hydrogen groups in one molecule as an initiator. .

Examples of the initiator include a hydroxyl group-containing compound and amines. Specifically, ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, butylethylpentanediol, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine Functional initiators; trifunctional initiators such as glycerin, trimethylolpropane, and triethanolamine; tetrafunctional initiators such as pentaerythritol, ethylenediamine, and aromatic diamine; and pentafunctional initiators such as diethylenetriamine.
Examples of the oxirane compound include alkylene oxides (AO) such as ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO); and tetrahydrofuran (THF).

  As the polyether polyol, an alkylene oxide adduct of an active hydrogen-containing compound (also referred to as a polyoxyalkylene polyol) is preferable. Among them, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), PPG (PPG-EO) having ethylene oxide (EO) added to its terminal, and polyalkylene glycols such as polytetramethylene glycol; Trifunctional polyether polyols such as glycerin alkylene oxide adducts are preferred.

Preferably, the polyether polyol has a low degree of unsaturation. The degree of unsaturation is the total amount of unsaturated groups contained per gram of polyether polyol, and corresponds to the amount of impurity monool. By using a high-purity material having a low degree of unsaturation, the initial curing property of the pressure-sensitive adhesive becomes good, and particularly, when the pressure-sensitive adhesive is exposed to a (moisture) heat environment, the surface of the adherend is removed after the pressure-sensitive adhesive sheet is removed again. Adherend contamination in which the adhesive component remains can be suppressed. The degree of unsaturation of the polyether polyol is preferably 0.07 meq / g or less, more preferably 0.04 meq / g or less, and particularly preferably 0.01 meq / g or less.
In the present specification, unless otherwise specified, the degree of unsaturation of the polyol is a value measured according to JIS K15576.7.

Examples of the polyamine that can be used as the active hydrogen group-containing compound (HX) include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, and 1,6. -Hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecane Diamine, hexamethylenediamine, trimethylhexamethylenediamine, iminobispropylamine, methyliminobispropylamine, 1,5-diamino-2-methylpentane, isophoronediamine, 1,3-bisaminomethylcyclohexane, 1-cyclohexylamino- 3-aminopro 3-aminomethyl-3,3,5-trimethyl-cyclohexylamine, dimethyleneamine having a norbornane skeleton, metaxylylenediamine (MXDA), hexamethylenediaminecarbamate, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and Aliphatic polyamines such as pentaethylenehexamine; 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4,4'-diaminodiphenylmethane, 2,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane 3,4′-diaminodiphenylmethane, 2,2′-diaminobiphenyl, 3,3′-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,3-tolylenediamine, 2,4-tolylenediamine, 2,5-tolylenediamine, 2,6-tolylenediamine, 3,4-tolylenediamine, diethyltoluenediamine and the like Aromatic polyamines; and the like.

  Examples of the amino alcohol that can be used as the active hydrogen group-containing compound (HX) include monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tri (hydroxymethyl) aminomethane, and 2-amino-2 Monoamines having a hydroxyl group such as -ethyl-1,3-propanediol; diamines having a hydroxyl group such as N- (2-hydroxypropyl) ethanolamine; and the like.

  Examples of the polythiol that can be used as the active hydrogen group-containing compound (HX) include methanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,2-benzenedithiol, 3-benzenedithiol, 1,4-benzenedithiol, 1,10-decanedithiol, 1,2-ethanedithiol, 1,6-hexanedithiol, 1,9-nonanedithiol, 1,8-octanedithiol, 1,5 -Pentanedithiol, 1,2-propanedithiol, 1,3-propadithiol, toluene-3,4-dithiol, 3,6-dichloro-1,2-benzenedithiol, 1,5-naphthalenedithiol, 1,2- Benzenedimethanethiol, 1,3-benzenedimethanethiol, 1,4-benzenedimethyl Thiol, 4,4′-thiobisbenzenethiol, 2,5-dimercapto-1,3,4-thiadiazole, 1,8-dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3-thiapentane, Examples thereof include 2-di-n-butylamino-4,6-dimercapto-s-triazine, and a thiol-terminated polymer (such as a polysulfide polymer).

The one or more active hydrogen group-containing compounds (HX) can include a bifunctional active hydrogen group-containing compound and / or a trifunctional or higher functional hydrogen-containing compound. In general, a bifunctional active hydrogen group-containing compound has two-dimensional crosslinkability and can impart appropriate flexibility to an adhesive layer. An active hydrogen group-containing compound having three or more functional groups has a three-dimensional cross-linking property and can impart an appropriate hardness to the adhesive layer. By selecting the number of functional groups (the number of active hydrogen groups) of each active hydrogen group-containing compound (HX), characteristics such as adhesive strength, cohesive strength, and removability of the urethane-based adhesive can be adjusted. The number of functional groups of each material can be selected so that properties such as adhesive strength, cohesive strength, and removability fall within a preferable range depending on the use and the like.
At least one type of active hydrogen group-containing compound (HX) contains a bifunctional active hydrogen group-containing compound and a trifunctional or more active hydrogen group-containing compound because it is easy to achieve both adhesive strength and removability. Is preferred.

  The number average molecular weight (Mn) per functional group of the active hydrogen group-containing compound (HX) is not particularly limited. Since the adhesive strength and wettability of the adhesive layer are suitable, the one or more active hydrogen group-containing compounds (HX) preferably have Mn of 500 or more, more preferably 1000 or more, particularly preferably 2000 or more, and most preferably. Preferably contains an active hydrogen group-containing compound of 3000 or more.

The active hydrogen group contained in the active hydrogen group-containing compound (HX) is preferably a hydroxyl group. That is, the active hydrogen group-containing compound (HX) is preferably a polyol.
When the active hydrogen group-containing compound (HX) is an amine compound, the interaction between the polar adherend and the hydroxyl group-terminated urethane prepolymer (UPH) increases to increase the adhesive strength of the adhesive layer, and particularly to the wet adhesion. ) In a thermal environment, adherend contamination may occur after re-peeling. When a polyol is used as the active hydrogen group-containing compound (HX), the interaction between the polar adherend and the hydroxyl-terminated urethane prepolymer (UPH) is relatively small, and the adherend contamination after re-peeling is suppressed. Can be. From the viewpoint of pot life and initial curability, the active hydrogen group-containing compound (HX) preferably contains a primary terminal hydroxyl group.

<Polyisocyanate (N)>
As the polyisocyanate (N), known ones can be used, and examples thereof include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

  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, and 2,6-tolylene diisocyanate. Range isocyanate, 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, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1,4-diethylbenzene 1,4-tetramethyl xylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate and the like.

  Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), 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 alicyclic polyisocyanate include isophorone diisocyanate (IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, and methyl-2,6. -Cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatomethyl) cyclohexane and the like.

  In addition, examples of the polyisocyanate include a trimethylolpropane adduct, a biuret, an allophanate, and a trimer of the polyisocyanate (the trimer contains an isocyanurate ring).

  As the polyisocyanate (N), an aliphatic polyisocyanate or an alicyclic polyisocyanate is preferable from the viewpoint of reducing the adhesive strength at an initial stage (before aging) and after aging (particularly after (wet) heat aging), and hexamethylene diisocyanate ( HDI) and isophorone diisocyanate (IPDI).

The preferred raw material mixing ratio of the hydroxyl group-terminated urethane prepolymer (UPH) is as follows.
The ratio (NCO / H ratio) of the mole number of the isocyanate group (NCO) of the polyisocyanate (N) to the total mole number of the active hydrogen group (H) of the plurality of types of active hydrogen group-containing compounds (HX) is 0. It is preferable to determine the raw material mixing ratio so as to be 20 to 0.95, more preferably 0.40 to 0.80. As the NCO / H ratio approaches 1, there is a tendency that the hydroxyl group-terminated urethane prepolymer (UPH) is more likely to gel during synthesis. When the NCO / H ratio is 0.95 or less, gelation during the synthesis of a hydroxyl-terminated urethane prepolymer (UPH) can be effectively suppressed.

<Catalyst>
For the polymerization of the hydroxyl group-terminated urethane prepolymer (UPH), one or more catalysts can be used as necessary. Known catalysts can be used, and examples thereof include tertiary amine compounds and organometallic compounds.
Examples of the tertiary amine compound include triethylamine, triethylenediamine, and 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU).
Examples of the organometallic compound include a tin compound and a non-tin compound.
Examples of the tin compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dioctyltin dilaurate, dibutyltin sulfide, tributyltin sulfide, and tributyltin oxide. , Tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.
Non-tin compounds include titanium compounds such as dibutyl titanium dichloride, tetrabutyl titanate and butoxy titanium trichloride; lead compounds such as lead oleate, 2-ethylhexanoate, lead benzoate and lead naphthenate; Irons such as iron-ethylhexanoate and iron acetylacetonate; cobalts such as cobalt benzoate and cobalt 2-ethylhexanoate; zincs such as zinc naphthenate and zinc 2-ethylhexanoate; zirconium naphthenate; Zirconium-based is exemplified.
The type and amount of the catalyst can be appropriately designed within a range in which the reaction proceeds favorably.

When a plurality of types of active hydrogen group-containing compounds (HX) having different reactivities are used in combination, a difference in these reactivities may lead to poor polymerization stability or liability to cloudiness of the reaction solution in a single catalyst system. is there. In this case, by using two or more kinds of catalysts, the reaction (for example, the reaction rate) can be easily controlled, and the above problem can be solved. In a system using a plurality of active hydrogen group-containing compounds (HX) having different reactivities, it is preferable to use two or more catalysts. The combination of two or more catalysts is not particularly limited, and examples thereof include a tertiary amine / organic metal system, a tin system / non-tin system, and a tin system / tin system. Preferred are tin-based / tin-based, and more preferred are dioctyltin dilaurate and tin 2-ethylhexanoate.
The mass ratio of tin 2-ethylhexanoate to dioctyltin dilaurate (tin 2-ethylhexanoate / dioctyltin dilaurate) is not particularly limited, and is preferably more than 0 and less than 1, more preferably 0.2 to 0.8. is there. When the mass ratio is less than 1, the catalyst activity is well-balanced, the gelation and cloudiness of the reaction solution are effectively suppressed, and the polymerization stability is further improved.

  The amount of the one or more catalysts is not particularly limited, and is preferably 0.01 to 100% based on the total amount of one or more active hydrogen group-containing compounds (HX) and one or more polyisocyanates (N). 1.0% by mass.

<Solvent>
For the polymerization of the hydroxyl group-terminated urethane prepolymer (UPH), one or more solvents can be used as necessary. Known solvents can be used as the solvent, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Ethyl acetate, toluene, and the like are particularly preferable from the viewpoint of the solubility of the hydroxyl-terminated urethane prepolymer (UPH) and the boiling point of the solvent.

<Polymerization method of hydroxyl-terminated urethane prepolymer (UPH)>
The polymerization method of the hydroxyl group-terminated urethane prepolymer (UPH) is not particularly limited, and a known polymerization method such as a bulk polymerization method and a solution polymerization method can be applied.
The polymerization procedure of the hydroxyl-terminated urethane prepolymer (UPH) includes:
Procedure 1) One or more active hydrogen group-containing compounds (HX), one or more polyisocyanates (N), one or more catalysts as needed, and one or more solvents as needed. Procedure for charging the flask;
Procedure 2) A flask is charged with one or more active hydrogen group-containing compounds (HX), optionally one or more catalysts, and optionally one or more solvents, and charged with one or more polyisocyanates ( A procedure of dropping N) is exemplified.
When a plurality of active hydrogen group-containing compounds (HX) and / or polyisocyanates (N) are used, the reaction may be performed in a plurality of stages.

  When a catalyst is used, the reaction temperature is preferably lower than 100 ° C, more preferably 50 to 95 ° C, and particularly preferably 60 to 85 ° C. When the reaction temperature is 100 ° C. or higher, it is difficult to control the reaction rate and polymerization stability, and it may be difficult to produce a hydroxyl-terminated urethane prepolymer (UPH) having a desired molecular weight. The reaction temperature when no catalyst is used is preferably 100 ° C. or higher, more preferably 110 ° C. or higher.

(Polyfunctional isocyanate compound (I))
Known compounds can be used as the polyfunctional isocyanate compound (I), and the compounds exemplified as the polyisocyanate (N) which is a raw material of the hydroxyl-terminated urethane prepolymer (UPH) (specifically, aromatic polyisocyanates, aliphatic Polyisocyanates, araliphatic polyisocyanates, alicyclic polyisocyanates, and their trimethylolpropane adduct / biuret / allophanate / trimer) can be used.

(Surfactant having cationic hydrophilic group (S))
The pressure-sensitive adhesive of the present invention contains one or more surfactants (S) having a cationic hydrophilic group and having an amine value of 0.1 to 160 mgKOH / g in terms of nonvolatile components.
As the surfactant (S), one or two or more known cationic surfactants and / or amphoteric surfactants can be used. The amine value is 0.1 to 160 mgKOH / g in terms of nonvolatile components. If it is, there is no particular limitation. Examples of the cationic hydrophilic group include primary to tertiary amino groups, primary to tertiary amine bases, and quaternary ammonium bases.
In addition, even if the structure or composition of a commercially available surfactant is unknown, as the surfactant (S), a surfactant having an amine value of 0.1 to 160 mgKOH / g in terms of a nonvolatile component is selected. I just need. One commercially available surfactant having such an amine value may contain a plurality of different cationic hydrophilic groups.

Specific examples of commercially available cationic surfactants or amphoteric surfactants that can be used as the surfactant (S) include:
Lubrizol Solspurs 9000, Solspurs 11200, Solspurs 13240, Solspurs 13940, Solspurs 16000, Solspurs 17000, Solspurs 18000, Solsperse 20000, Solsperse 24000SC, Solsperse 24000GR, Solsperse 26000, Solsperse 28000, Solsperse 32,500, Solsperse 3500 Solspers 32550, Solspers 32600, Solspers 33000, Solspers 34750, Solspers 35100, Solspers 35200, Solspers 37500, Solspers 38500, Solspers 39000, Solspers 53095, Solspers 56000, Solspers 71 00, SOLSPERSE 76500, SOLSPERSE D510, SOLSPERSE D530, SOLSPERSE L300, SOLSPERSE K200, SOLSPERSE K210, SOLSPERSE K500, Solsperse R700;
Kyoeisha's Floren DOPA-15B, Floren DOPA-15BHFS, Floren DOPA-17HF, Floren DOPA-22, Floren DOPA-35, Floren G-600, Floren G-820, Floren NC-500, Floren KDG-2400;
Hinoact KF-1300M, Hinoact KF-1500, Hinoact KF-1700, Hinoact T-6000, Hinoact T-8000, Hinoact T-8000E, Hinoact T-9100, Hinoact A-110, Hinoact NB manufactured by Kawaken Fine Chemical Company;
TEGODispers 650, TEGODispers 660C, TEGODispers 662C, TEGODispers 670, TEGODispers685, TEGODispers700, TEGODispers710, TEGODispers 760W manufactured by Evonik;
Addisper PB821, Addisper PB822, Addisper PB824, Addispar PB881, manufactured by Ajinomoto Fine Techno Co.
DISPERBYK-106, DISPERBYK-108, DISPERBYK-140, DISPERBYK-142, DISPERBYK-145, DISPERBYK-161, DISPERBYK-162, DISPERBYKK-163, DISPERBYK-164, DISPERBYKYB-168, made by BYK-Chemie. 180, DISPERBYK-182, DISPERBYK-184, DISPERBYK-185, DISPERBYK-2000, DISPERBYK-2001, DISPERBYK-2008, DISPERBYK-2009, DISPERBYK-2013, DISPERBYK-2022, DISPERBYKY-20Y 2026, DISPERBYK-2050, DISPERBYK-2055, DISPERBYK-2150, DISPERBYK-2155, DISPERBYK-2163, DISPERBYK-2164, BYK-9076, BYK-9077, ANTI-TERRA-U / U100, ANTI-TERIRA TERRA-250, DISPERBYK, DISPERBYK-180, DISPERBYK-184, DISPERBYK-185, DISPERBYK-187, DISPERBYK-191, DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2013, DISPERBYKY-20Y D Pigment dispersing agents such as SPERBYK-2050, DISPERBYK-2055, DISPERBYK-2061;
NOF Corporation's Filanol PA-075F, Filanol PA-085C, Filanol PA-107P, ESREAM AD-3172M, ESREAM AD-374M, ESREAM AD-508E;
Daiichi Kogyo Seiyaku Co., Ltd. Sharoll DC902P, Sharoll DC303P;
Polymeric surfactants such as Texnol IL55, Texnol L7, and Texnol CP-81 manufactured by Nippon Emulsifier Co .;

Before and after aging by adding at least one surfactant (S) having a cationic hydrophilic group to an adhesive containing the active hydrogen group-containing compound (H) and the polyfunctional isocyanate compound (I) The adhesive strength of the adhesive layer can be reduced, and an increase in the adhesive strength of the adhesive layer in a (moist) heat environment can be suppressed. As a result, even when exposed to a (moist) heat environment, it is possible to form a pressure-sensitive adhesive layer having good removability and free from adherent contamination in which the pressure-sensitive adhesive component remains on the surface of the adherend after re-peeling. It becomes possible.
Although this mechanism is not always clear, it is speculated as follows.
A glass substrate, an ITO / glass substrate in which an ITO (indium tin oxide) film is formed on a glass substrate, and a surfactant having a cationic hydrophilic group for the interfacial interaction between an adherend such as an optical member and an adhesive layer ( It is considered that by cutting off S), the adhesive layer has low adhesive strength before and after aging, and the removability is improved.

When the amine value of the surfactant (S) in terms of non-volatile components is 0.1 mg KOH / g or more, the above-mentioned effects (particularly, reduction of the adhesive strength of the adhesive layer in a (wet) heat environment and removability by the adhesive) Improvement and reduction of adherend contamination) can be significantly exhibited.
If the amine value of the surfactant (S) is too high, the interaction between the adherend and the surfactant (S) becomes too large. In particular, under a (wet) heat environment, the surfactant (S) Bleed out may occur and adherend contamination may occur after re-peeling. When the amine value is 160 mgKOH / g or less in terms of nonvolatile components, it is considered that the interaction between the adherend and the adhesive layer can be cut off while suppressing the bleed out of the surfactant (S).

  Since the above-mentioned functions and effects (especially, the lowering of the adhesive strength of the adhesive layer in a (wet) heat environment, the improvement of removability and the reduction of contamination of the adherend) are effectively exhibited, the amine value is calculated as a nonvolatile content. It is preferably 0.1 to 150 mgKOH / g, more preferably 0.1 to 100 mgKOH / g, particularly preferably 0.1 to 60 mgKOH / g, and most preferably 0.1 to 30 mgKOH / g.

  The acid value of the surfactant (S) is not particularly limited, and a smaller one is preferred. The acid value is preferably 40 mgKOH / g or less, more preferably 40 mgKOH / g or less, in terms of non-volatile content, from the viewpoint of the initial curing property, and particularly from the viewpoint of reducing the adhesive strength of the adhesive layer in a (wet) heat environment and improving the removability thereof. Is 20 mgKOH / g or less, particularly preferably 10 mgKOH / g or less, and most preferably 0 mgKOH / g.

The amine value, acid value, and non-volatile content can be measured by the following methods.
<Amine value>
A 1 g sample is precisely weighed and placed in a stoppered Erlenmeyer flask, dissolved in 100 ml of a mixed solution of toluene / ethanol (volume ratio: toluene / ethanol = 1/1), and then 0.1N-alcoholic hydrochloric acid solution is used. Perform a titration. The amine value (unit: mgKOH / g) is determined by the following equation.
Amine value = {(5.61 × a × F) / S} / (non-volatile concentration / 100)
In the formula, each symbol indicates the following parameter.
S: sampled amount (g),
a: consumption of 0.1N-alcoholic hydrochloric acid solution (ml),
F: Factor of 0.1N-alcoholic hydrochloric acid solution.
<Acid value>
A 1 g sample is precisely weighed and placed in a stoppered Erlenmeyer flask, 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution is added and dissolved, and then a 0.1 N-alcoholic potassium hydroxide solution is added. Perform titration with The acid value (unit: mgKOH / g) is determined by the following equation.
Acid value = {(5.61 × a × F) / S} / (non-volatile concentration / 100)
In the formula, each symbol indicates the following parameter.
S: sampled amount (g),
a: consumption of 0.1 N-alcoholic potassium hydroxide solution (ml),
F: Factor of 0.1N-alcoholic potassium hydroxide solution.

<Nonvolatile content>
Approximately 1 g of the sample solution is weighed in a metal container, dried in an oven at 150 ° C. for 20 minutes, the residue is weighed, and the residual ratio is calculated.

The weight average molecular weight (Mw) of the surfactant (S) is not particularly limited, and is preferably 500 or more, more preferably 1000 or more, and particularly preferably 2000 or more. When Mw is 500 or more, the bleed out of the surfactant (S) after aging (particularly after (wet) heat aging) can be effectively suppressed, and the adherend contamination can be improved.
As the weight average molecular weight (Mw) of the surfactant (S), a catalog value or an actually measured value can be adopted.
The weight average molecular weight (Mw) can be determined by the method described in the section of Examples.

Related documents of the present invention include Patent Documents 1 to 4 listed in the “Background Art” section.
Patent Document 1 discloses a pressure-sensitive adhesive sheet (surface protective film) using a urethane-based pressure-sensitive adhesive containing a leveling agent (claim 7). Surfactants can be used as leveling agents. However, this document does not describe a surfactant having a cationic hydrophilic group, and neither describes nor suggests the addition of a surfactant having a specific amine value having a cationic hydrophilic group and its effect.

  Patent Document 2 discloses a pressure-sensitive adhesive containing a polyurethane resin having a hydroxyl group (A), a reactive compound (B) having a functional group capable of reacting with a hydroxyl group, and a surfactant (C) ( Claim 1). Examples of the surfactant (C) include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant (Paragraph 0124).

  Patent Document 3 describes a pressure-sensitive adhesive sheet (surface protective film) using a urethane-based pressure-sensitive adhesive containing an antistatic agent (AS agent) (claim 3, paragraph 0022). Nonionic, cationic, anionic and amphoteric surfactants are mentioned as antistatic agents (paragraph 0023).

In Patent Document 4,
A urethane prepolymer obtained by reacting a polyol (a) having a polypropylene glycol skeleton or a polyester skeleton with a polyisocyanate (b), and a urethane urea resin (A) obtained by reacting a polyamino compound (c) with:
An ionic compound (B) containing a fluorine atom-containing anion as a component,
A curing agent (C),
An antistatic pressure-sensitive adhesive composition comprising a silane coupling agent (D) having an alkoxysilyl group is disclosed (Claim 1).
In the above composition, the ionic compound (B) is used as an antistatic agent. In Patent Document 4, in Comparative Examples 21 and 24, alkyl bis (2-hydroxylethyl) methylammonium chloride, which is a cationic surfactant, is used as an antistatic agent.

However, Patent Documents 2 to 4 do not disclose or suggest the addition of a surfactant having a specific amine value having a cationic hydrophilic group to a urethane-based pressure-sensitive adhesive and its effect.
In addition, the code | symbol of each component described in patent documents 1-4 is the code | symbol described in these documents, and has nothing to do with the code | symbol used for each component of this invention.

  As the skeleton structure of the surfactant (S), there are a single type in which the number of hydrophilic groups is one and a comb type in which the number of hydrophilic groups is plural, and any of them may be used. Since the above-mentioned effects (particularly, lowering the adhesive strength of the adhesive layer in a (wet) heat environment, thereby improving removability and reducing contamination of the adherend) are effectively exhibited, the number of hydrophilic groups is 1 One type is preferred.

(Plasticizer (P))
From the viewpoint of reducing the adhesive strength of the adhesive layer and improving the wettability, the adhesive of the present invention can further contain one or more plasticizers (P) as necessary. The plasticizer (P) is not particularly limited, and is preferably an organic acid ester from the viewpoint of compatibility with other components.

  Examples of esters of monobasic or polybasic acids and alcohols include, for example, isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isostearyl palmitate, isocetyl stearate, octyldodecyl oleate, phthalate Dibutyl phthalate, dioctyl phthalate, diheptyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, diisodecyl adipate, diisostearyl adipate, dibutyl sebacate, diisocetyl sebacate, tributyl acetylcitrate, tributyl trimellitate, trimellitate Trioctyl acid, trihexyl trimellitate, trioleyl trimellitate, and triisocetyl trimellitate.

  Examples of esters of other acids with alcohols include, for example, unsaturated fatty acids or branched acids such as myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, and isostearic acid, and ethylene glycol, propylene glycol, and glycerin. , Trimethylolpropane, pentaerythritol, and esters with alcohols such as sorbitan.

  Examples of the ester of a monobasic acid or a polybasic acid and a polyalkylene glycol include, for example, polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurate, polyethylene glycol dioleate, and dipolyethylene glycol methyl adipate Ether and the like.

  From the viewpoint of improving wettability, the molecular weight (formula weight or Mn) of the organic acid ester is preferably from 250 to 1,000, more preferably from 400 to 900, and particularly preferably from 500 to 850. When the molecular weight is 250 or more, the heat resistance of the pressure-sensitive adhesive layer is good, and when the molecular weight is 1,000 or less, the wettability of the pressure-sensitive adhesive is good.

  From the viewpoint of suppressing adherend contamination, it is preferable that the amount of the plasticizer (P) is small. The amount of the one or more plasticizers (P) relative to 100 parts by mass of the active hydrogen group-containing compound (H) is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less.

(solvent)
The pressure-sensitive adhesive of the present invention can contain one or more solvents as required. Known solvents can be used as the solvent, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. From the viewpoint of the solubility of the active hydrogen group-containing compound (H) and the boiling point of the solvent, ethyl acetate and toluene are particularly preferred.

(Deterioration inhibitor)
The pressure-sensitive adhesive of the present invention can contain one or more kinds of deterioration preventing agents as required. Thereby, it is possible to suppress the deterioration of various characteristics due to long-term use of the adhesive layer. Examples of the alteration inhibitor include a hydrolysis resistance agent, an antioxidant, an ultraviolet absorber, and a light stabilizer.

<Hydrolysis resistant agent>
When a carboxy group is generated by a hydrolysis reaction in the adhesive layer under a (wet) heat environment or the like, a hydrolysis resistant agent can be used to block the carboxy group. Examples of the hydrolysis stabilizer include carbodiimide-based, oxazoline-based, and epoxy-based. Above all, carbodiimides are preferred from the viewpoint of the effect of inhibiting hydrolysis.

A carbodiimide-based hydrolysis inhibitor is a compound having one or more carbodiimide groups in one molecule.
Examples of the monocarbodiimide compound include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, diphenylcarbodiimide, and naphthylcarbodiimide.
The polycarbodiimide compound can be produced by subjecting a diisocyanate to a decarboxylation reaction in the presence of a carbodiimidization catalyst. Here, as the diisocyanate, for example, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4 '-Diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, and the like. Examples of the carbodiimidization catalyst include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl-2-phospholene-1-oxide, 1-ethyl- Examples thereof include 2-phospholene-1-oxide and phospholene oxides such as 3-phospholene isomers thereof.

Examples of the oxazoline-based hydrolysis inhibitor include 2,2′-o-phenylenebis (2-oxazoline), 2,2′-m-phenylenebis (2-oxazoline), and 2,2′-p-phenylenebis. (2-oxazoline), 2,2′-p-phenylenebis (4-methyl-2-oxazoline), 2,2′-m-phenylenebis (4-methyl-2-oxazoline), 2,2′-p -Phenylenebis (4,4'-dimethyl-2-oxazoline), 2,2'-m-phenylenebis (4,4'-dimethyl-2-oxazoline), 2,2'-ethylenebis (2-oxazoline) , 2,2'-tetramethylenebis (2-oxazoline), 2,2'-hexamethylenebis (2-oxazoline), 2,2'-octamethylenebis (2-oxazoline), 2,2'-ethylenebis (4-me -2-oxazoline), and 2,2'-diphenylenebis (2-oxazoline).

  Examples of the epoxy-based hydrolyzing agent include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol; sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, And polyglycidyl ethers of aliphatic polyols such as trimethylolpropane; polyglycidyl ethers of alicyclic polyols such as cyclohexanedimethanol; terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, and sebacic acid. Diglycidyl esters or polyglycidyl esters of aliphatic or aromatic polycarboxylic acids; resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p- Diglycidyl ethers or polyglycidyl ethers of polyhydric phenols such as loxyphenyl) propane, tris- (p-hydroxyphenyl) methane, and 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane; N, N- N-glycidyl derivatives of amines such as diglycidylaniline, N, N-diglycidyltoluidine and N, N, N ', N'-tetraglycidyl-bis- (p-aminophenyl) methane; triglycidyl derivatives of aminophenol Triglycidyl tris (2-hydroxyethyl) isocyanurate and triglycidyl isocyanurate; and epoxy resins such as orthocresol type epoxy resin and phenol novolak type epoxy resin.

  The amount of the hydrolysis stabilizer to be added is not particularly limited, and is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4.5 parts by mass, based on 100 parts by mass of the active hydrogen group-containing compound (H). And particularly preferably 0.5 to 3 parts by mass.

<Antioxidant>
Examples of the antioxidant include a radical scavenger and a peroxide decomposer. Examples of the radical scavenger include a phenol compound and an amine compound. Examples of the peroxide decomposer include a sulfur compound and a phosphorus compound.

  Examples of the phenolic compound 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, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 3,9-bis [1,1-dimethyl-2- [Β- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane Benzenepropanoic acid, 3,5-bis (1,1-dimethylethyl) -4-hydroxy-, C7-C9 side chain alkyl ester, 1,1,3-tris (2-methyl-4-hydroxy-5- t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′ , 5′-Di-tert-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis- (4′-hydroxy-3′-tert-butylphenyl) butyric acid] glycol ester, 1,3,5-tris (3 ′, 5′-di-tert-butyl-4′-hydroxybenzyl) -S-triazine-2,4,6- (1H, 3H, 5H) trione, tocopherol and the like And the like.

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

  Examples of the phosphorus compound include triphenyl phosphite, diphenyl isodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl ditridecyl) phosphite, and cyclic neopentane tetrayl Bis (octadecylphosphite), tris (nonylphenyl) phosphite, tris (monononylphenyl) phosphite, tris (dinonylphenyl) phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa- 10-phosphaphenanthrene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10 -Desiloxy- , 10-Dihydro-9-oxa-10-phosphaphenanthrene, tris (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) Phosphite, cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-methylphenyl) phosphite, and 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite And the like.

By using an antioxidant, thermal degradation of the active hydrogen group-containing compound (H) can be prevented.
The addition amount of the antioxidant is not particularly limited, and is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and particularly preferably 100 parts by mass of the active hydrogen group-containing compound (H). Is 0.2 to 2 parts by mass.

  As the antioxidant, from the viewpoint of stability and antioxidant effect, it is preferable to use at least one phenolic compound as a radical scavenger, and at least one phenolic compound as a radical scavenger and a peroxide decomposer. More preferably, one or more phosphorus compounds are used in combination. As an antioxidant, it is particularly preferable to use a phenolic compound as a radical scavenger and a phosphorus compound as a peroxide decomposer in combination, and to use these antioxidants and the above-mentioned hydrolysis stabilizer in combination. .

<Ultraviolet absorber>
Examples of the ultraviolet absorber include a benzophenone compound, a benzotriazole compound, a salicylic acid compound, an oxalic anilide compound, a cyanoacrylate compound, and a triazine compound.
The amount of the ultraviolet absorber added is not particularly limited, and is preferably 0.01 to 3 parts by mass, more preferably 0.1 to 2.5 parts by mass, based on 100 parts by mass of the active hydrogen group-containing compound (H). Particularly preferably, it is 0.2 to 2 parts by mass.

<Light stabilizer>
Examples of the light stabilizer include a hindered amine compound and a hindered piperidine compound. The addition amount of the light stabilizer is not particularly limited, and is preferably 0.01 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, based on 100 parts by mass of the active hydrogen group-containing compound (H). Particularly preferably, it is 0.2 to 1 part by mass.

(Antistatic agent (AS agent))
The pressure-sensitive adhesive of the present invention optionally contains one or more antistatic agents (AS agents) (excluding those corresponding to the active hydrogen group-containing compound (H) and the surfactant (S)). Can be. Examples of the antistatic agent include an inorganic salt, an ionic liquid, an ionic solid, and a surfactant. Among them, an ionic liquid and an ionic solid are preferable. The “ionic liquid” is also called a room temperature molten salt, and is a salt having a fluidity at 25 ° C.

  Examples of the inorganic salts include sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, ammonium sulfate, potassium nitrate, and sodium nitrate. , Sodium carbonate, and sodium thiocyanate.

  Examples of the ionic liquid containing an imidazolium ion include 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1,3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide, and 1-butyl And -3-methylimidazolium bis (trifluoromethylsulfonyl) imide.

  Examples of the ionic liquid containing a pyridinium ion include 1-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-butylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexylpyridinium bis (trifluoromethylsulfonyl) imide, 1-octylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4- Methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide, 1-methylpyridinium bis (perfluoroethylsulfonyl) Imide, and 1-methyl-pyridinium bis (perfluorobutylsulfonyl) imide, and the like.

  Examples of the ionic liquid containing an ammonium ion include 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide, trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N- Propyl ammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethane Sulfonyl) imide, and tri-n-butylmethylammonium bistrifluoromethanesulfonimide.

  In addition, commercially available ionic liquids such as a pyrrolidinium salt, a phosphonium salt, and a sulfonium salt can be appropriately used.

  The ionic solid is a salt of a cation and an anion, like the ionic liquid, but is a substance that shows a solid property at 25 ° C. under normal pressure. Preferred examples of the cation include an alkali metal ion, a phosphonium ion, a pyridinium ion, and an ammonium ion.

  Examples of the ionic solid containing an alkali metal ion include lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium bispentafluoroethylsulfonylimide, lithium bisheptafluoropropylsulfonylimide, lithium bisnonanefluorobutylsulfonylimide, and sodium bisulfonylimide. Fluorosulfonylimide, sodium bistrifluoromethylsulfonylimide, sodium bispentafluoroethylsulfonylimide, sodium bisheptafluoropropylsulfonylimide, sodium bisnonanefluorobutylsulfonylimide, potassium bisfluorosulfonylimide, potassium bistrifluoromethylsulfonylimide, potassium bis Pentafluoroethylsulfonyluy De, potassium bis heptafluoropropyl imide and potassium bis nonane-fluoro-butyl imide, and the like.

  Examples of the ionic solid containing a phosphonium ion include, for example, tetrabutylphosphonium bisfluorosulfonylimide, tetrabutylphosphonium bistrifluoromethylsulfonylimide, tetrabutylphosphonium bispentafluoroethylsulfonylimide, tetrabutylphosphonium bisheptafluoropropylsulfonylimide, and tetrabutylphosphonium Bisnonanefluorobutylsulfonylimide, tributylhexadecylphosphonium bisfluorosulfonylimide, tributylhexadecylphosphonium bistrifluoromethylsulfonylimide, tributylhexadecylphosphonium bispentafluoroethylsulfonylimide, tributylhexadecylphosphonium bisheptafluoropropylsulfonylimide, tribu Hexadecylphosphonium bisnonanefluorobutylsulfonylimide, tetraoctylphosphonium bisfluorosulfonylimide, tetraoctylphosphonium bistrifluoromethylsulfonylimide, tetraoctylphosphonium bispentafluoroethylsulfonylimide, tetraoctylphosphonium bisheptafluoropropylsulfonylimide, and tetra Octylphosphonium bisnonanefluorobutylsulfonylimide and the like.

  As the ionic solid containing a pyridinium ion, for example, 1-hexadecyl-4-methylpyridinium bisfluorosulfonylimide, 1-hexadecyl-4-methylpyridinium bistrifluoromethylsulfonylimide, 1-hexadecyl-4-methylpyridinium bispentafluoroethylsulfonyl Imide, 1-hexadecyl-4-methylpyridinium bisheptafluoropropylsulfonylimide, 1-hexadecyl-4-methylpyridiniumbisnonanefluorobutylsulfonylimide, and the like.

  Examples of ionic solids containing ammonium ions include, for example, lauryltrimethylammonium chloride, tributylmethylbistrifluoromethylsulfonylimide, tributylmethylbispentafluoroethylsulfonylimide, tributylmethylbisheptafluoropropylsulfonylimide, tributylmethylmubisnonanefluorobutylsulfonylimide Octyltributylbistrifluoromethylsulfonylimide, octyltributylbispentafluoroethylsulfonylimide, octyltributylbisheptafluoropropylsulfonylimide, octyltributylmubisnonanefluorobutylsulfonylimide, tetrabutylbisfluorosulfonylimide, tetrabutylbistrifluoromethylsulfonyl Imide, tet Butyl bis pentafluoroethylsulfonyl imide, tetrabutyl bis heptafluoropropylsulfonyl imide, and tetrabutyl arm bis nonane-fluoro-butyl imide and the like.

  In addition, a known ionic solid having a cation such as a pyrrolidinium ion, an imidazolium ion, or a sulfonium ion can be appropriately used.

  Surfactants other than the surfactant (S) include nonionic surfactants and anionic surfactants, and each type is classified into a low molecular surfactant and a high molecular surfactant. .

Examples of the nonionic low molecular surfactant include glycerin fatty acid ester, polyoxyalkylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamine fatty acid ester, and fatty acid diethanolamide. Can be
Examples of the anionic low molecular surfactant include an alkyl sulfonate, an alkylbenzene sulfonate, and an alkyl phosphate.
Examples of the amphoteric low molecular surfactant include alkyl betaine and alkyl imidazolium betaine.

Examples of the nonionic polymer surfactant include a polyetherester amide type, an ethylene oxide-epichlorohydrin type, and a polyetherester type.
Examples of the anionic polymer surfactant include a polystyrene sulfonic acid type and the like.
Examples of the amphoteric polymer surfactant include an amino acid-type amphoteric surfactant such as a higher alkylaminopropionate and a betaine-type amphoteric surfactant such as a higher alkyldimethylbetaine and a higher alkyldihydroxyethylbetaine.

  The amount of the antistatic agent (AS agent) to be added is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, per 100 parts by mass of the active hydrogen group-containing compound (H).

(Leveling agent)
The pressure-sensitive adhesive of the present invention can contain a leveling agent, if necessary. By adding a leveling agent, the leveling property of the adhesive layer can be improved. Examples of the leveling agent include an acrylic leveling agent, a fluorine-based leveling agent, a silicone-based leveling agent, and the like. From the viewpoint of suppressing contamination of the adherend after re-peeling the pressure-sensitive adhesive sheet, an acrylic leveling agent is preferred.

  The amount of the leveling agent to be added is not particularly limited, and is preferably based on 100 parts by mass of the active hydrogen group-containing compound (H) from the viewpoint of suppressing adherend contamination after re-peeling the pressure-sensitive adhesive sheet and improving the leveling property of the pressure-sensitive adhesive layer. The amount is 0.001 to 2 parts by mass, more preferably 0.01 to 1.5 parts by mass, particularly preferably 0.1 to 1 part by mass.

(Other optional components)
The pressure-sensitive adhesive of the present invention can contain other optional components as needed, as long as the effects of the present invention are not impaired. Other optional components include catalysts, resins other than urethane resins, fillers (such as talc, calcium carbonate, and titanium oxide), metal powders, coloring agents (such as pigments), foils, softeners, and conductive materials. Agents, silane coupling agents, lubricants, corrosion inhibitors, heat stabilizers, weather stabilizers, polymerization inhibitors, defoamers and the like.
When the pressure-sensitive adhesive of the present invention contains a catalyst, it is preferable to add a known catalyst action inhibitor such as acetylacetone for the purpose of improving the pot life of the pressure-sensitive adhesive.

(Blending ratio)
The pressure-sensitive adhesive of the present invention comprises one or more active hydrogen group-containing compounds (H) (preferably a hydroxyl-terminated urethane prepolymer (UPH)), one or more polyfunctional isocyanate compounds (I), and a cationic hydrophilic group. It contains the surfactant (S) as an essential component, and further contains one or more optional components as necessary. The mixing ratio is not particularly limited, but the preferable mixing ratio is as follows.
The amount of one or more polyfunctional isocyanate compounds (I) is preferably 1 to 30 parts by mass, more preferably 3 to 20 parts by mass, based on 100 parts by mass of one or more active hydrogen group-containing compounds (H). When the amount of the one or more polyfunctional isocyanate compounds (I) is at least 1 part by mass, the cohesive force of the adhesive layer will be good, and when it is at most 30 parts by mass, the pot life will be good.

Since the above-mentioned effects (particularly, lowering the adhesive strength of the adhesive layer in a (moist) heat environment, thereby improving removability and reducing adherend contamination) are effectively exhibited, one or more types of active hydrogen The amount of the one or more surfactants (S) relative to 100 parts by mass of the group-containing compound (H) is 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass. 0 parts by mass.
If the amount of the surfactant (S) is too small, the effect of the addition may not be effectively exhibited. If the added amount of the surfactant (S) is excessive, the adherend may be contaminated by bleed out of the surfactant (S) when exposed to a (moist) heat environment.

(Production method of adhesive)
The method for producing the pressure-sensitive adhesive of the present invention is not particularly limited.
One or more polyfunctional isocyanate compounds (I), one or more active hydrogen group-containing compounds (H) (preferably hydroxyl-terminated urethane prepolymers (UPH) synthesized by the above method) By adding and mixing the surfactant (S) and, if necessary, one or more optional components, the pressure-sensitive adhesive of the present invention can be produced.

  The gel fraction of the pressure-sensitive adhesive after curing is preferably 70% or more, more preferably 80% or more, particularly preferably 90% or more, and most preferably 95% or more. When the gel fraction is 70% or more, the cohesive strength of the pressure-sensitive adhesive layer becomes good, and good adhesive strength and removability can be obtained even after being exposed to a (moist) heat environment. Can reduce adherend contamination. The gel fraction can be determined by the method described in the section of [Example].

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention includes a base sheet and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive of the present invention. The adhesive layer can be formed on one side or both sides of the base sheet. If necessary, the exposed surface of the adhesive layer can be covered with a release sheet. The release sheet is released when the pressure-sensitive adhesive sheet is attached to the adherend.

FIG. 1 shows a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 denotes an adhesive sheet, reference numeral 11 denotes a base sheet, reference numeral 12 denotes an adhesive layer, and reference numeral 13 denotes a release sheet. The pressure-sensitive adhesive sheet 10 is a single-sided pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is formed on one side of a base sheet.
FIG. 2 shows a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the second embodiment of the present invention. In FIG. 2, reference numeral 20 denotes an adhesive sheet, reference numeral 21 denotes a base sheet, reference numerals 22A and 22B denote adhesive layers, and reference numerals 23A and 23B denote release sheets.

  The substrate sheet is not particularly limited, and examples thereof include a resin sheet, paper, and metal foil. The base sheet may be a laminated sheet in which any one or more layers are stacked on at least one surface of the base sheet. The surface of the base sheet on which the pressure-sensitive adhesive layer is to be formed may be subjected to a corona discharge treatment and an easy-adhesion treatment such as application of an anchor coat agent, if necessary.

The constituent resin of the resin sheet is not particularly limited, and an ester resin such as polyethylene terephthalate (PET); an olefin resin such as polyethylene (PE) and polypropylene (PP); a vinyl resin such as polyvinyl chloride; Amide resins; urethane resins (including foams); combinations thereof; and the like.
The thickness of the resin sheet excluding the polyurethane sheet is not particularly limited, and is preferably 15 to 300 μm. The thickness of the polyurethane sheet (including the foam) is not particularly limited, and is preferably 20 to 50,000 μm.

The paper is not particularly limited, and includes plain paper, coated paper, art paper, and the like.
The constituent metal of the metal foil is not particularly limited, and examples thereof include aluminum, copper, and combinations thereof.

  The release sheet is not particularly limited, and a known release sheet obtained by subjecting a surface of a base sheet such as a resin sheet or paper to a known release treatment such as application of a release agent can be used.

The pressure-sensitive adhesive sheet can be manufactured by a known method.
First, the pressure-sensitive adhesive of the present invention is applied to the surface of a substrate sheet to form a coating layer composed of the pressure-sensitive adhesive of the present invention. Known coating methods can be applied, and examples include 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.
Next, the coating layer is dried and cured to form an adhesive layer made of a cured product of the adhesive of the present invention. The heating and drying temperature is not particularly limited, and is preferably about 60 to 150 ° C. The thickness (thickness after drying) of the adhesive layer varies depending on the application, but is preferably 0.1 to 200 μm.
Next, if necessary, a release sheet is attached to the exposed surface of the adhesive layer by a known method.
As described above, a single-sided pressure-sensitive adhesive sheet can be manufactured.
By performing the above operation on both sides, a double-sided PSA sheet can be manufactured.

  Contrary to the above method, the pressure-sensitive adhesive of the present invention is applied to the surface of the release sheet to form a coating layer composed of the pressure-sensitive adhesive of the present invention, and then the coating layer is dried and cured to obtain the present invention. May be formed, and a base sheet may be laminated on the exposed surface of the pressure-sensitive adhesive layer.

  The method for producing the pressure-sensitive adhesive sheet is preferably a coating step of coating a pressure-sensitive adhesive on a base sheet, and a heating step of heating and drying the formed coating layer to form a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive. A step of winding the obtained pressure-sensitive adhesive sheet around a core to form a pressure-sensitive adhesive sheet roll, and a curing step of curing the pressure-sensitive adhesive sheet roll.

As described above, according to the present invention, the initial curing property is good, and the adhesive strength is reduced both at the initial stage (before aging) and after aging (especially after (wet) heat aging), and the good re-curability is obtained. It is possible to provide a pressure-sensitive adhesive which has a releasability and can form a pressure-sensitive adhesive layer with little adherend contamination after re-peeling, and a pressure-sensitive adhesive sheet using the same.
ADVANTAGE OF THE INVENTION According to this invention, even if it exists in a (wet) heat environment, the increase in adhesive force is suppressed, it has favorable re-peeling property, and the adhesive layer with little adherend contamination after re-peeling is formed. And a pressure-sensitive adhesive sheet using the same.

[Use]
The pressure-sensitive adhesive sheet of the present invention can be used in the form of a tape, a label, a seal, a double-sided tape, or the like. The pressure-sensitive adhesive sheet of the present invention is suitably used as a surface protection sheet, a cosmetic sheet, a non-slip sheet, and the like.
Flat panel displays such as a liquid crystal display (LCD) and an organic electroluminescence display (OELD), and a touch panel display combining such a flat panel display with a touch panel include a television (TV), a personal computer (PC), a mobile phone, And it is widely used in electronic devices such as portable information terminals.
The pressure-sensitive adhesive sheet of the present invention includes a flat panel display and a touch panel display (collectively referred to simply as a “display”), and a substrate (a glass substrate and an ITO on a glass substrate) manufactured or used in these manufacturing processes. (ITO / glass substrate or the like on which (indium tin oxide) film is formed) and a surface protection sheet for optical members and the like.

  Hereinafter, synthesis examples, examples according to the present invention, and comparative examples will be described. In the following description, “parts” means “parts by mass”, “%” means “% by mass”, and “RH” means relative humidity unless otherwise specified.

[Measurement of Mn and Mw]
The number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured by a gel permeation chromatography (GPC) method. The measurement conditions were as follows. Note that both Mn and Mw are values in terms of polystyrene.
<Measurement conditions>
Equipment: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: Two LF-804 manufactured by Shodex were connected in series,
Detector: Differential refractive index detector (RID-10A),
Solvent: tetrahydrofuran (THF),
Flow rate: 1 mL / min,
Solvent temperature: 40 ° C.
Sample concentration: 0.2%
Sample injection volume: 100 μL.

[material]
The materials used are as follows.
(Active hydrogen group-containing compound (HX))
<Relatively high molecular weight polyol having Mn of 100 or more>
(HX-11): Kuraray polyol P-1010, manufactured by Kuraray Co., Ltd., bifunctional polyester polyol, hydroxyl value 112.2,
(HX-12): PEG400, manufactured by Sanyo Chemical Industries, Ltd., bifunctional polyether polyol, hydroxyl value 280.5,
(HX-13): Sannics PP-2000, manufactured by Sanyo Chemical Industries, Ltd., bifunctional polypropylene glycol, hydroxyl value 56.1,
(HX-14): Preminol 5001F, manufactured by Asahi Glass Co., difunctional polyether polyol, hydroxyl value 28.1, degree of unsaturation 0.02,
(HX-15): GL3000, manufactured by Sanyo Chemical Industries, Ltd., trifunctional polyether polyol, hydroxyl value 56.1,
(HX-16): GP3000, manufactured by Sanyo Chemical Industries, Ltd., trifunctional polyether polyol, hydroxyl value 56.1,
(HX-17): Exenol 851, manufactured by Asahi Glass Co., Ltd., trifunctional polyether polyol, hydroxyl value 25.1, degree of unsaturation 0.04.
(HX-18): Preminol 7012, manufactured by Asahi Glass Co., Ltd., trifunctional polyether polyol, hydroxyl value 16.8, degree of unsaturation 0.02.
The unit of the degree of unsaturation is meq / g.

<Polyamine>
(HX-21): IPDA, isophoronediamine, a bifunctional polyamine manufactured by EVONIK.
<Amino alcohol>
(HX-22): AMP, 2-amino-2-methyl-1-propanol, bifunctional amino alcohol.
<Relatively low molecular weight polyol with Mn less than 100>
(HX-31): 1,3 PDO, 1,3-propanediol, bifunctional polyol.
Table 2-1 and Table 2-2 show the number of functional groups, Mn, and Mn per functional group of each active hydrogen group-containing compound (HX). For polyols, the same table also shows the series of terminal hydroxyl groups (terminal OH).

(Polyisocyanate (N))
(N-11): HDI, hexamethylene diisocyanate, manufactured by Sumika Covestrourethane Co., Ltd., Desmodur H,
(N-12): TDI, tolylene diisocyanate (a mixture of 2,4-tolylene diisocyanate (80% by mass) and 2,6-tolylene diisocyanate (20% by mass)), manufactured by Tosoh Corporation, Coronate T-80 ,
(N-13): IPDI, isophorone diisocyanate, Desmodur I, manufactured by Sumika Covestrourethane Co., Ltd.
Table 2-1 and Table 2-2 show the number of functional groups, Mn, and Mn per functional group of each polyisocyanate (N).

(Polyfunctional isocyanate compound (I))
(I-11) HDI adduct, Coronate HL, manufactured by Tosoh Corporation, hexamethylene diisocyanate (HDI) / trimethylolpropane (TMP) adduct,
(I-12) HDI Nurate, Sumidur N-3300, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate (HDI) / isocyanurate.

(Surfactant having cationic hydrophilic group (S), other surfactant (R))
Table 1 shows a list of the surfactant (S) having a cationic hydrophilic group and other surfactants (R) used. In the table, the amine value and the acid value are values in terms of nonvolatile components (unit is mgKOH / g).

(Plasticizer (P))
(P-11): Exepearl MOL, methyl oleate, manufactured by Kao Corporation
(P-12): Monosizer W262, polyetherester plasticizer, manufactured by DIC.
(Antioxidant (C))
(C-11): IRGANOX 1010, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], a phenolic antioxidant, manufactured by BASF.

[Synthesis Example of Hydroxyl-terminated Urethane Prepolymer (UPH) Solution]
(Synthesis Example 1) (Single-stage polymerization method)
In a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping funnel, 5 parts by mass of an active hydrogen group-containing compound (HX-11) and an active hydrogen group-containing compound (HX-18) 95 parts by mass, 1.6 parts by mass of polyisocyanate (N-11), 67 parts by mass of toluene, 0.020 parts by mass of dioctyltin dilaurate and 0.008 parts by mass of tin 2-ethylhexanoate as catalysts were charged and mixed. The content liquid was gradually heated to 75 ° C. and reacted for 3 hours.
The ratio of the number of moles of isocyanate groups of the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups of all the active hydrogen group-containing compounds (HX) used in the reaction (NCO / H ratio) is as follows: 0.49.
After confirming the disappearance of the remaining isocyanate groups by infrared spectroscopy (IR analysis), the content liquid was cooled to 30 ° C. to terminate the reaction. Finally, 0.56 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl-terminated urethane prepolymer (UPH-1) having a non-volatile content of 60%, a viscosity of 2,100 cps, was obtained. The obtained hydroxyl-terminated urethane prepolymer had Mw = 105,000.
Table 2-1 shows the composition, the NCO / H ratio, and the Mw of the obtained hydroxyl-terminated urethane prepolymer.

(Synthesis Examples 2 to 12) (Single-stage polymerization method)
In Synthesis Examples 2 to 12, the one-stage polymerization method was performed in the same manner as in Synthesis Example 1 except that the type of the active hydrogen group-containing compound (HX), the type of the polyisocyanate (N), and the mixing ratio thereof were changed. Thus, a solution of colorless and transparent hydroxyl-terminated urethane prepolymers (UPH-2) to (UPH-11) was obtained.
Tables 2-1 and 2-2 show the composition, NCO / H ratio, and Mw of the obtained hydroxyl-terminated urethane prepolymer in each synthesis example.

(Synthesis Example 13) (Multi-stage polymerization method)
In a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a thermometer, and a dropping funnel, 100 parts by mass of an active hydrogen group-containing compound (HX-13) and 17 parts by mass of polyisocyanate (N-13) , 29.3 parts by mass of toluene and 0.01 part by mass of dioctyltin dilaurate as a catalyst were charged and mixed. The content liquid was gradually heated to 100 ° C., and reacted for 2 hours. Thereafter, the mixture was cooled to 25 ° C., 90.7 parts by mass of ethyl acetate and 0.5 parts by mass of acetylacetone were added, and 3.4 parts by mass of an active hydrogen group-containing compound (HX-21) was added dropwise over 1 hour. After maintaining the liquid temperature at 25 ° C. and continuing the reaction for another 1 hour, 1.2 parts by mass of an active hydrogen group-containing compound (HX-22) was added and reacted. After confirming disappearance of the remaining isocyanate groups by infrared spectroscopy (IR analysis), the reaction was terminated.
As described above, a solution of a colorless and transparent hydroxyl-terminated urethane prepolymer (UPH-12) having a nonvolatile content of 45%, a viscosity of 3,100 cps and a viscosity of 3,100 cps was obtained. The obtained hydroxyl-terminated urethane prepolymer had Mw = 52,000.
Table 2-2 shows the composition, the NCO / H ratio, and the Mw of the obtained hydroxyl-terminated urethane prepolymer.

(Synthesis Example 14) (Multi-stage polymerization method)
In a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping funnel, 100 parts by mass of an active hydrogen group-containing compound (HX-18) and polyisocyanate (N-13) 6.5. Parts by mass, 45.7 parts by mass of toluene, and 0.02 parts by mass of dioctyltin dilaurate as a catalyst were charged and mixed. The content liquid was gradually heated to 80 ° C. and reacted for 2 hours to obtain an isocyanate group-terminated prepolymer. Thereafter, the mixture was cooled to 60 ° C., and after adding 26.6 parts by mass of ethyl acetate, 2.5 parts by mass of an active hydrogen group-containing compound (HX-31) was added and reacted. After confirming the disappearance of the remaining isocyanate groups by infrared spectroscopy (IR analysis), the content liquid was cooled to 30 ° C. to terminate the reaction. Finally, 0.43 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl-terminated urethane prepolymer (UPH-13) having a nonvolatile content of 60% and a viscosity of 2,800 cps was obtained. The obtained hydroxyl-terminated urethane prepolymer had Mw = 98,000.
Table 2-2 shows the composition, the NCO / H ratio, and the Mw of the obtained hydroxyl-terminated urethane prepolymer.

[Production of urethane-based pressure-sensitive adhesives and pressure-sensitive adhesive sheets]
(Example 1)
100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH-1) solution obtained in Synthesis Example 1 (in terms of nonvolatile components), 10 parts by mass of a polyfunctional isocyanate compound (I-11), and a surfactant having a cationic hydrophilic group ( S-11) 0.5 part by mass, 1.0 part by mass of the antioxidant (C-1), and 100 parts by mass of ethyl acetate as a solvent were mixed and stirred with a disper to obtain a urethane-based pressure-sensitive adhesive. . In addition, the usage amount of each material other than the solvent indicates a non-volatile content conversion value (the same applies to other examples and comparative examples). The composition is shown in Table 3-1.
A 50 μm thick polyethylene terephthalate (PET) film (Lumirror T-60, manufactured by Toray Industries, Inc.) was prepared as a base sheet. Using a comma coater (registered trademark), the obtained urethane-based pressure-sensitive adhesive was applied on one side of the base sheet so that the thickness after drying became 12 μm. Next, the formed coating layer was dried at 100 ° C. for 2 minutes to form an adhesive layer. A 38 μm-thick release sheet (Super Stick SP-PET38, manufactured by Lintec Co., Ltd.) was stuck on this adhesive layer to obtain an adhesive sheet.
Regarding the evaluation of the initial curing property, after curing for 5 hours under the condition of 23 ° C. and 50% RH, the evaluation was performed. Other evaluations were performed after curing for one week under the condition of 23 ° C. and 50% RH.

(Examples 2 to 42, Comparative Examples 1 to 5)
Examples 2 to 42 and Comparative Examples 1 to 5 correspond to Example 1 except that the types and mixing ratios of the materials used were changed as shown in Tables 3-1 to 3-6 and Table 4. Similarly, the production of a urethane-based pressure-sensitive adhesive and a pressure-sensitive adhesive sheet and their evaluation were performed.

[Evaluation items and evaluation methods]
Evaluation items and evaluation methods for the pressure-sensitive adhesive and the pressure-sensitive adhesive sheet are as follows.
(Gel fraction)
A test piece having a width of 30 mm and a length of 100 mm was cut out from the pressure-sensitive adhesive sheet after curing for one week in an atmosphere of 23 ° C. and 50% RH. The test piece was stuck on a SUS mesh (opening: 0.077 mm, wire diameter: 0.05 mm), and then immersed in ethyl acetate. After extraction at 50 ° C. for 24 hours, the extract was dried at 100 ° C. for 30 minutes, and the gel fraction (% by mass) after curing was calculated based on the following formula (1).
Gel fraction (% by mass) = (G2 / G1) × 100 (1)
In the above equation, each symbol indicates the following parameter.
G1: mass of the adhesive layer before extraction with ethyl acetate,
G2: Mass of the adhesive layer after extraction with ethyl acetate and drying.

(Initial curing)
A test piece having a width of 30 mm and a length of 100 mm was cut out from the pressure-sensitive adhesive sheet after being cured for 5 hours in an atmosphere of 23 ° C. and 50% RH. The test piece was stuck on a SUS mesh (opening: 0.077 mm, wire diameter: 0.05 mm), and then immersed in ethyl acetate. After extraction at 50 ° C. for 24 hours, the extract was dried at 100 ° C. for 30 minutes, and the initial gel fraction (% by mass) was calculated based on the following equation (2).
Initial gel fraction (% by mass) = (G4 / G3) × 100 (2)
In the above equation, each symbol indicates the following parameter.
G3: mass of the adhesive layer before extraction with ethyl acetate,
G4: Mass of the adhesive layer after extraction with ethyl acetate and drying.
The evaluation criteria are as follows.
：: Excellent initial gel fraction of 70% by mass or more.
：: Good, initial gel fraction is 40% by mass or more and less than 70% by mass.
Δ: The initial gel fraction was 20% by mass or more and less than 40% by mass, and practically usable.
X: The initial gel fraction is less than 20% by mass, which is not practical.

(Adhesive strength before heating)
A test piece having a width of 25 mm and a length of 100 mm was cut out from the pressure-sensitive adhesive sheet after curing for one week in an atmosphere of 23 ° C. and 50% RH. Next, under an atmosphere of 23 ° C. and 50% RH, the release sheet was peeled off from the test piece, the exposed adhesive layer was adhered to the surface of a caustic soda glass plate, and a 2 kg roll was reciprocated one time and pressed. Then, it was left for 24 hours in an atmosphere of 23 ° C. and 50% RH. Next, based on JISZ0237, the adhesive strength (adhesive strength before heating) was measured using a tensile tester (Tensilon: manufactured by Orientec) at a peeling speed of 300 mm / min and a peeling angle of 180 °. The evaluation criteria are as follows.
◎: Less than 20 mN / 25 mm, excellent.
：: good from 20 mN / 25 mm to less than 50 mN / 25 mm.
Δ: 50 mN / 25 mm or more and less than 200 mN / 25 mm, practical.
X: 200 mN / 25 mm or more, not practical.

(Rise of adhesive strength after heating)
A test piece having a width of 25 mm and a length of 100 mm was cut out from the pressure-sensitive adhesive sheet after curing for one week in an atmosphere of 23 ° C. and 50% RH. Next, under an atmosphere of 23 ° C. and 50% RH, the release sheet was peeled off from the test piece, the exposed adhesive layer was stuck to a caustic soda glass plate, and a 2 kg roll was reciprocated one time and pressed. Then, it was left for 1 hour in an atmosphere at 150 ° C. Next, after air-cooling for 30 minutes in an atmosphere of 23 ° C. and 50% RH, a peeling speed of 300 mm / min and a peeling angle of 180 ° were measured using a tensile tester (Tensilon: manufactured by Orientec) according to JISZ0237. Was used to measure the adhesive strength (adhesive strength after heating at 150 ° C.). The rate of increase in adhesive strength after heating was calculated based on the following equation (3).
Rate of increase in adhesive strength after heating (%) = (N2 / N1) × 100 (3)
In the above equation, each symbol indicates the following parameter.
N1: the value of the adhesive strength before heating measured in Evaluation 2,
N2: value of adhesive strength after heating at 150 ° C. measured in Evaluation 3.
The evaluation criteria are as follows.
A: Less than 150%, excellent.
Good: 150% or more and less than 300%, good.
Δ: 300% or more and less than 500%, practical.
X: 500% or more, not practical.

(Adhesive contamination control)
Two test pieces having a width of 70 mm and a length of 100 mm were cut out from the pressure-sensitive adhesive sheet after being cured for one week in an atmosphere of 23 ° C. and 50% RH. With respect to each test piece, the release sheet was peeled off in an atmosphere of 23 ° C. and 50% RH, and a caustic soda glass plate was stuck to the exposed surface of the adhesive layer, and pressed with a laminator. One of the obtained two laminates was left in an oven set at 60 ° C.-90% RH for 72 hours. The other laminate was left in an oven set at 85 ° C.-85% RH for 24 hours. Each of the two laminates was taken out of the oven, air-cooled in an atmosphere of 23 ° C. and 50% RH for 3 hours, and then the adhesive sheet was peeled off the glass plate to evaluate adherend contamination. The surface of the glass plate on which the adhesive sheet was stuck in the dark room was irradiated with LED (light emitting diode) lamp light, and evaluated by visual observation. The evaluation criteria are as follows.
A: Excellent in that no adhesion component of the adhesive layer was observed on the glass surface in any of the samples under the heating conditions of 60 ° C.-90% RH and 85 ° C.-85% RH.
：: No adhesion component was observed on the glass surface in the sample under the heating condition of 60 ° C.-90% RH, but in the sample under the heating condition of 85 ° C.-85% RH, the sample was thin at one to three places on the glass surface. Good, with adhesion of adhesive layer components observed.
C: At a temperature of 60 ° C.-90% RH, a sample having a heating condition of 60 ° C.-90% RH shows attachment of a thin adhesive layer component at 1 to 3 places on the glass surface. Adhesion of a thin adhesive layer component is observed on one or two or more places on the glass surface, and practical application is possible.
×: In the samples under both heating conditions of 60 ° C.-90% RH and 85 ° C.-85% RH, adhesion of a thin adhesive layer component is observed at four or more places on the glass surface and / or at one or two places on the glass surface. Unavailable due to adhesion of strong adhesive layer components.

[Evaluation results]
The evaluation results are shown in Tables 3-1 to 3-6 and Table 4.
In Examples 1 to 42,
One or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups in one molecule,
A polyfunctional isocyanate compound (I),
A surfactant having a cationic hydrophilic group (S),
The surfactant (S) has an amine value of 0.1 to 160 mgKOH / g in terms of nonvolatile components,
A urethane-based pressure-sensitive adhesive was produced in which the content of the surfactant (S) was 0.01 to 20 parts by mass based on 100 parts by mass of the active hydrogen group-containing compound (H).
In each of these examples, a pressure-sensitive adhesive having good initial curability can be produced, the pressure-sensitive adhesive strength before heating is small, the rate of increase in the pressure-sensitive adhesive strength after heating at 150 ° C. is small, and even when exposed to a moist heat environment. It was possible to produce a pressure-sensitive adhesive sheet with little adherend contamination.

  The pressure-sensitive adhesive sheet obtained in Comparative Example 1 in which the surfactant (S) having a cationic hydrophilic group and the other surfactant (R) were not added had a large rate of increase in pressure-sensitive adhesive strength after heating and was poor. there were.

  The pressure-sensitive adhesive sheet obtained in Comparative Example 2, in which the amount of the surfactant (S) having a cationic hydrophilic group added to 100 parts by mass of the active hydrogen group-containing compound (H) was more than 20 parts by mass, had an initial curability and heat. The increase rates of the adhesive strength before and the adhesive strength after heating were poor, and the adherend contamination was remarkable.

  The pressure-sensitive adhesive sheet obtained in Comparative Example 3 to which a comparative surfactant (R) having a cationic hydrophilic group having an amine value of more than 160 mgKOH / g in terms of nonvolatile content was added, the pressure-sensitive adhesive strength after heating at 150 ° C. The rate of increase was large and poor.

  The pressure-sensitive adhesive sheets obtained in Comparative Examples 4 and 5 to which a comparative surfactant (R) having a cationic hydrophilic group having an amine value of less than 0.1 mgKOH / g in terms of nonvolatile content was added, after heating at 150 ° C. The rate of increase in the adhesive strength was large, and the adherend contamination was remarkable.

  The present invention is not limited to the above embodiments and examples, and design changes can be made as appropriate without departing from the spirit of the present invention.

10, 20 Adhesive sheet 11, 21 Base sheet 12, 22A, 22B Adhesive layer 13, 23A, 23B Release sheet

Claims (6)

One or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups in one molecule,
One or more polyfunctional isocyanate compounds (I),
And one or more surfactants (S) having a cationic hydrophilic group,
The surfactant (S) has an amine value of 0.1 to 160 mgKOH / g in terms of nonvolatile components,
A urethane-based pressure-sensitive adhesive, wherein the content of the surfactant (S) is 0.01 to 20 parts by mass based on 100 parts by mass of the active hydrogen group-containing compound (H).   The active hydrogen group-containing compound (H) is a hydroxyl-terminated urethane prepolymer (UPH), which is a reaction product of one or more active hydrogen group-containing compounds and one or more polyisocyanates. Urethane adhesive.   The urethane-based pressure-sensitive adhesive according to claim 1, wherein the surfactant (S) has one hydrophilic group.   The urethane-based pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the surfactant (S) has an amine value of 0.1 to 60 mgKOH / g in terms of nonvolatile components.   The urethane according to any one of claims 1 to 4, further comprising at least one alteration preventing agent selected from the group consisting of an antioxidant, a hydrolysis resistance agent, an ultraviolet absorber, and a light stabilizer. Adhesive.   An adhesive sheet comprising: a base sheet; and an adhesive layer comprising a cured product of the adhesive according to claim 1.

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