KR20190003768A - Pressure-sensitive adhesive and pressure-sensitive adhesive sheet - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good releasability even when placed under a harsh high-temperature and high-humidity environment. The pressure-sensitive adhesive of the present invention is a pressure-sensitive adhesive which comprises at least one bifunctional polyether polyol (x1) having at least one ethyleneoxy (EO) group in one molecule and at least one trifunctional polyol (x1) having at least one ethyleneoxy A polyurethane polyol (A) which is a copolymerization reaction product of various kinds of polyol (x) including an ether polyol (x2) with at least one polyisocyanate (y), and a polyfunctional isocyanate compound (B).

Description

Pressure-sensitive adhesive and pressure-sensitive adhesive sheet

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

BACKGROUND ART [0002] Conventionally, an adhesive sheet having a pressure-sensitive adhesive layer formed on a substrate sheet as a surface protective sheet for various members is widely used. As the pressure sensitive adhesive, there are mainly an acrylic pressure sensitive adhesive and a urethane pressure sensitive adhesive. The acrylic pressure-sensitive adhesive is excellent in adhesive strength, but it has a strong adhesive force and is not good in releasability after being adhered to an adherend. Particularly, after a lapse of time in a high-temperature and high-humidity environment, re-peeling properties are further lowered due to an increase in adhesive force, and adherend contamination remaining on the surface of an adherend tends to be easily generated after peeling. On the other hand, the urethane pressure-sensitive adhesive has a suitable adhesive property to an adherend, has good adhesion to an adherend, and is also excellent in re-release property.

Patent Document 1 discloses a urethane pressure-sensitive adhesive in which a polyfunctional isocyanate compound is blended with a polyurethane polyol obtained by reacting a polyester polyol and a polyether polyol with a polyisocyanate in the presence of two kinds of catalysts (claim 1). It is described that this urethane pressure-sensitive adhesive is good in re-peeling property after being adhered to an adherend and left under the condition of 40 占 폚 -65% RH (paragraphs 0051 and Examples 1 to 6 in Table 2).

In the present specification, " RH " indicates relative humidity unless otherwise specified.

Patent Document 2 discloses a urethane pressure-sensitive adhesive comprising a polyurethane polyol, a polyfunctional isocyanate compound and a fatty acid ester having 10 to 30 carbon atoms (claim 1). It is described that this urethane pressure-sensitive adhesive is good in releasability after standing for 24 hours under the condition of 40 ° C-80% RH after bonding to an adherend (paragraphs 0049 and Examples 1 to 4 in Table 1)

Patent Document 3 discloses a urethane-based pressure-sensitive adhesive comprising a polyurethane polyol, a polyfunctional isocyanate compound, and at least one compound selected from a polyalkylene glycol compound, an epoxy compound, and a phosphate ester compound ( Claim 1). This urethane pressure-sensitive adhesive is described in that it has good releasability after standing for 96 hours under the condition of 60 占 폚 -90% RH after adhering to an adherend (paragraphs 0061 and Examples 1 to 18 in Table 1).

In addition, Patent Document 4 is related to the present invention. The content of this document will be described later.

Japanese Patent Application Laid-Open No. 2000-73040 Japanese Patent Laid-Open Publication No. 2011-190420 Japanese Patent Application Laid-Open No. 2015-7226 Japanese Patent Application Laid-Open No. 2015-151429

A flat panel display such as a liquid crystal display (LCD) and an organic electroluminescence display (ELD), and a touch panel display in which a related flat panel display and a touch panel are combined, is used for a TV, a personal computer (PC) And is widely used in electronic devices such as information terminals.

The urethane adhesive sheet is suitably used as a surface protective sheet for flat panel displays, touch panel displays, and substrates and optical members manufactured or used in these manufacturing processes.

The use range of the electronic device is enlarged and the possibility of being placed under a high temperature and high humidity environment which is more severe than in the past is continuously generated.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good re-peelability even under a harsh high temperature and high humidity environment, and a pressure-sensitive adhesive sheet using the same.

In the pressure-sensitive adhesive of the present invention,

At least one bifunctional polyether polyol (x1) having at least one ethyleneoxy (EO) group in one molecule and at least one trifunctional polyether polyol (x2) having at least one ethyleneoxy (EO) (A) which is a copolymerization reaction product of one or more polyisocyanates (y), and a polyfunctional isocyanate compound (B).

The pressure-sensitive adhesive of the present invention is a composition comprising various kinds of materials including the above-mentioned components (A) and (B). However, in the pressure-sensitive adhesive, various kinds of blending components including the components (A) and (B) Sometimes it does not exist clearly. That is, the pressure sensitive adhesive of the present invention may contain a reaction product obtained by partially reacting various kinds of compounding ingredients including the components (A) and (B).

The pressure-sensitive adhesive sheet of the present invention comprises a base sheet and an adhesive layer composed of the above-mentioned pressure-sensitive adhesive of the present invention.

In general, a sheet material is referred to as a " tape ", " film ", or " sheet " depending on its thickness and width. In the present specification, the terms " sheet " are used as the terms indicating the concept including them without particularly distinguishing them.

Unless otherwise specified in the specification, "molecular weight" means a number average molecular weight (Mn). "Mn" is the number average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC) measurement.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good re-peelability even when placed under a harsh high temperature and high humidity environment, and an adhesive sheet using the same.

1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to a first embodiment of the present invention,
2 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to a second embodiment of the present invention.

"adhesive"

In the pressure-sensitive adhesive of the present invention,

At least one bifunctional polyether polyol (x1) having at least one ethyleneoxy (EO) group in one molecule and at least one trifunctional polyether polyol (x2) having at least one ethyleneoxy (EO) (A), which is a copolymerization reaction product of one or more polyisocyanates (y), and a polyfunctional isocyanate compound (B).

(Polyurethane polyol (A))

The polyurethane polyol (A) is a reaction product obtained by copolymerization reaction of various kinds of polyol (x) with at least one polyisocyanate (y). One or more polyurethane polyols (A) may be used. The copolymerization reaction can be carried out in the presence of a catalyst, if necessary. For the copolymerization reaction, a solvent may be used if necessary.

≪ Polyol (x) >

The various polyols (x) include at least one bifunctional polyether polyol (x1) having at least one EO group in one molecule and at least one trifunctional polyether polyol having at least one EO group in one molecule (x2).

The various polyols (x) may contain one or more different polyether polyols in combination with the polyether polyols (x1) and (x2) as long as the effects of the present invention are not impaired.

As the polyether polyol, known ones can be used. Examples of the polyether polyol include a compound (an addition polymer) obtained by using an active hydrogen-containing compound having at least two active hydrogens in one molecule as an initiator and addition polymerization of at least one oxirane compound.

Examples of the initiator include hydroxyl group-containing compounds and amines. Specific examples thereof include ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, butyl ethyl pentanediol, Bifunctional initiators such as phthalic anhydride, phthalic anhydride, phoronediamine, and xylenediamine; Trifunctional initiators such as glycerin, trimethylol propane, 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); Tetrahydrofuran (THF) and the like.

As the polyether polyol, an alkylene oxide adduct (also referred to as " polyoxyalkylene polyol ") which is an active hydrogen-containing compound is preferable. Among them, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG) and polytetramethylene glycol; And a trifunctional polyether polyol such as an alkylene oxide adduct of glycerin.

As described above, in the present invention, at least one bifunctional polyether polyol (x1) having at least one EO group in at least one molecule as various polyols (x) and at least one bifunctional polyether polyol And a trifunctional polyether polyol (x2) is used.

The bifunctional polyether polyol (x1) has a two-dimensional crosslinking property and can impart appropriate flexibility to the adhesive layer. The trifunctional polyether polyol (x2) has a three-dimensional crosslinking property and can impart an appropriate hardness to the adhesive layer. By using these in combination, an adhesive layer having an appropriate cohesive force and adhesive force tends to be easily obtained.

Further, the polyether polyols (x1) and (x2) all have an EO group, whereby the following actions and effects can be obtained.

In general, when a structure in which a pressure sensitive adhesive sheet is adhered to an adherend is exposed to a high temperature and high humidity environment, reattachability deteriorates due to an increase in adhesive force of the pressure sensitive adhesive layer, and adherend contamination remaining on the surface of the adherend after re- There may be cases.

The pressure-sensitive adhesive of the present invention using the bifunctional polyether polyol (x1) having an EO group and the trifunctional polyether polyol (x2) having an EO group as the raw material polyol (x) of the polyurethane polyol (A) It is possible to form a pressure-sensitive adhesive layer having good re-peelability even if it is placed under a high-temperature and high-humidity environment. In order to illustrate this, in the items of [Examples] described later, the temperature and humidity conditions of the re-peelability evaluation are set more severely than those of Patent Documents 1 to 3 listed in the "Background Technology" section.

Although the mechanism of the action and effect is not necessarily clear, the present inventors think as follows.

In general, under a high-temperature drying environment, since deterioration of re-peelability of the adhesive layer can not be seen, it is presumed that degradation of re-peelability of the adhesive layer is due to moisture. Hydrophilicity of the pressure-sensitive adhesive layer is improved by using two kinds of polyether polyols (x1) and (x2) having an EO group as the raw material polyol (x) of the polyurethane polyol (A). As a result, migration of moisture between the adhesive layer and the external environment is apt to occur, and even if moisture intrudes from the outside into the adhesive layer, water is likely to be discharged from the adhesive layer to the external environment, so that the moisture content in the adhesive layer can be kept relatively small, It is presumed that it is difficult to be influenced by

Further, in the pressure-sensitive adhesive of the present invention using the two kinds of polyether polyols (x1) and (x2) having EO groups as the raw material polyol (x) of the polyurethane polyol (A), the effect of improving the coatability is also obtained. The mechanism of this action effect is not necessarily clear, but the present inventors assume the following.

The hardness of the polyurethane polyol (A) can be improved by using two kinds of polyether polyols (x1) and (x2) having an EO group as the starting polyol (x). As a result, it is presumed that the coating unevenness such as roll marking and deformation can be suppressed and a coating film having good surface smoothness can be formed.

The coating film having improved hardness is hardly affected by drying wind or the like in the process of drying and curing, so that good surface smoothness can be maintained. Therefore, according to the present invention, an adhesive layer having a high surface smoothness can be formed.

The bifunctional polyether polyol (x1) is a compound (additional polymer) obtained by addition polymerization of at least one oxirane compound containing ethylene oxide (EO) to the bifunctional initiator. Among them, polyalkylene glycols obtained by addition polymerization of at least one alkylene oxide (AO) containing ethylene oxide (EO) to the bifunctional initiator are preferred. The content of the EO group in the polyalkylene glycol is preferably as large as possible. As the bifunctional polyether polyol (x1), polyethylene glycol (PEG) is particularly preferable because the content of the EO group is large. That is, the at least one bifunctional polyether polyol (x1) preferably contains PEG.

The number average molecular weight (Mn) of the bifunctional polyether polyol (x1) is not particularly limited and effectively exhibits the above-mentioned action and effect (an effect of improving the releasability of the pressure-sensitive adhesive layer when placed in a high temperature and high humidity environment and an effect of improving coatability) , It is preferably 150 to 6,000, more preferably 200 to 4,000, and particularly preferably 200 to 2,000.

The trifunctional polyether polyol (x2) is a compound (addition polymer) obtained by addition polymerization of at least one oxirane compound containing ethylene oxide (EO) to the trifunctional initiator. Among them, a compound (addition polymer) obtained by addition polymerization of at least one alkylene oxide (AO) containing ethylene oxide (EO) to the above-mentioned trifunctional initiator is preferable.

From the viewpoint of reactivity with the bifunctional polyether polyol (x1), it is preferable that the trifunctional polyether polyol (x2) has at least an EO group at the terminal. Examples of the trifunctional polyether polyol (x2) having at least the EO group at the terminal include glycerin EO adduct obtained by addition polymerization of at least one ethylene oxide (EO) to glycerin, glycerin EO adduct obtained by adding one or more propylene oxide (PO) (Hereinafter also referred to as " glycerin polypropylene glycol end-terminated ethylene glycol modification ") obtained by addition polymerization of at least one ethylene oxide (EO) in this order.

The number average molecular weight (Mn) of the trifunctional polyether polyol (x2) is not particularly limited, and the above-mentioned action and effect (the effect of improving the releasability of the adhesive layer and the effect of improving the coating property when placed in a high temperature and high humidity environment) , It is preferably 200 to 6,000, more preferably 400 to 5,000, and particularly preferably 1,000 to 4,000.

In view of the balance between the cohesive force and the adhesive force,

When the total amount of at least one bifunctional polyether polyol (x1) and at least one trifunctional polyether polyol (x2) is 100 parts by mass,

It is more preferable that the amount of the at least one difunctional polyether polyol (x1) is 1 to 40 parts by mass and the amount of the at least one trifunctional polyether polyol (x2) is 99 to 60 parts by mass,

It is more preferable that the amount of the at least one difunctional polyether polyol (x1) is 1 to 30 parts by mass and the amount of the at least one trifunctional polyether polyol (x2) is 99 to 70 parts by mass,

It is more preferable that the amount of the at least one difunctional polyether polyol (x1) is 5 to 15 parts by mass and the amount of the at least one trifunctional polyether polyol (x2) is 95 to 85 parts by mass.

As related literature of the present invention, there is Patent Document 4 listed in the item of "Background Art". This document discloses a urethane-based pressure sensitive adhesive comprising a prepolymer of polyurethane and a carboxylic acid ester, and the carboxylic acid ester satisfies at least one of the following (Condition A) and (Condition B) (Claim 1).

(Condition A) The carboxylic acid ester contains an ether bond in the molecule.

(Condition B) The carboxylic acid ester contains 31 or more carbon atoms in one molecule.

In the item [Examples] of Patent Document 4, a pressure-sensitive adhesive using a polyol having an EO group is produced. However, unlike the present invention, only polyfunctional polyether polyols (specifically, glycerin PO.EO adducts) are used in the [Examples of Patent Document 4] (Table 3). In the items of [Examples] of Patent Document 4, the re-peeling property of the adhesive layer is not evaluated. However, the inventors of the present invention found that the adhesive layer of the present invention is more adhesive than the adhesive layer described in Patent Document 4, (See the item [Example], Comparative Example 2).

The other polyether polyol to be used as the raw material polyol (x) may be a bifunctional polyether polyol (x3) having no EO group, a trifunctional polyether polyol (x3) having no EO group, or a polyfunctional polyether polyol to be.

The raw material polyol (x) can be added to various kinds of polyether polyols containing at least one bifunctional polyether polyol (x1) and at least one trifunctional polyether polyol (x2) May comprise at least one polyester polyol.

As the polyester polyol, known ones can be used. As the polyester polyol, for example, a compound (esterified product) obtained by an esterification reaction of at least one polyol component and at least one acid component can be mentioned.

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

Examples of the acid component of the raw material include succinic acid, methyl succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimeric acid, Cyclohexanedicarboxylic acid, 4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4-biphenyldicarboxylic acid, and acid anhydrides thereof. .

Examples of the polyester polyol other than the above include compounds obtained by ring-opening polymerization of one or more lactones such as polycaprolactone, poly (beta -methyl- gamma -valerolactone), and polyvalerolactone (ring- Also,

The number average molecular weight (Mn) of the polyester polyol is not particularly limited and is preferably 200 to 8,000, more preferably 500 to 6,000, particularly preferably 500 to 3,000, and most preferably 1,000 to 3,000. If the molecular weight is too low, the reactivity is high and gelation may occur. If the molecular weight is excessive, the reactivity is low and the cohesive force of the polyurethane polyol (A) itself may become insufficient.

≪ Polyisocyanate (y) >

As the polyisocyanate compound (y), known ones can be used, and examples thereof include aromatic polyisocyanates, aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, and alicyclic polyisocyanates.

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

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

Examples of the aromatic aliphatic polyisocyanate include ω, ω'-diisocyanate-1,3-dimethylbenzene, ω'-diisocyanate-1,4-dimethylbenzene, ω'-diisocyanate- Benzene, 1,4-tetramethylxylene diisocyanate, and 1,3-tetramethylxylene diisocyanate.

Examples of the alicyclic polyisocyanate include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl Cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatomethyl) cyclohexane, and 1,4 Bis (isocyanatomethyl) cyclohexane, and the like.

In addition, examples of the polyisocyanate include trimethylolpropane duct, burette, and trimer of the above polyisocyanate (the trimer includes an isocyanurate ring).

As the polyisocyanate (y), 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, and 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate) are preferable.

<Catalyst>

As the catalyst, 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 compounds include tin-based compounds and non-saponified compounds.

Examples of the tin compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, Tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and 2-ethyl And tin hexanoate.

Examples of non-saponified compounds include titanium-based compounds such as dibutyltitanium dichloride, tetrabutyl titanate, and butoxy titanium trichloride; Lead lead such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; Iron systems such as iron 2-ethylhexanoate and iron acetylacetate; Cobalt-based compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; A zinc system such as zinc naphthenate and zinc 2-ethylhexanoate; And zirconium compounds such as zirconium naphthenate.

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

When the reactivities of various kinds of polyols (x) used in combination are different, due to the difference in reactivity, gelation or clouding of the reaction solution may easily occur in a single catalyst system. In this case, it is easy to control the reaction (for example, the reaction rate) by using two kinds of catalysts, so that the above problem can be solved. That is, in the present invention, it is preferable to use two kinds of catalysts. The combination of the two kinds of catalysts is not particularly limited, and examples thereof include a tertiary amine / organic metal system, a tin system / non-sapphire system, and a tin system / tin system. Preferably, it is a tin / tin system, more preferably dibutyl tin dilaurate and 2-ethylhexanoate tin.

The mass ratio of tin 2-ethylhexanoate and dibutyltin dilaurate (2-ethylhexanoate / dibutyltin dilaurate) is not particularly limited and is preferably more than 0 and less than 1, 0.6. When the mass ratio is 1 or more, the balance of the catalytic activity is not good and gelation may easily occur.

The amount of the at least one catalyst to be used is not particularly limited and is preferably 0.01 to 1.0% by mass, based on the total amount of the various polyols (x) and at least one polyisocyanate (y).

<Solvent>

In the polymerization of the polyurethane polyol (A), one or more kinds of solvents may be used, if necessary. As the solvent, known solvents can be used, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Ethyl acetate and toluene are particularly preferable in view of the solubility of the polyurethane polyol (A) and the boiling point of the solvent.

<Polymerization method>

The polymerization method of the polyurethane polyol (A) is not particularly limited, and known polymerization methods such as bulk polymerization and solution polymerization can be applied.

The order of polymerization is not particularly limited,

Step 1) a step of collecting a plurality of kinds of polyol (x), at least one polyisocyanate (y), at least one catalyst, and optionally at least one solvent, collectively in a flask;

Step 2) A procedure of preparing various kinds of polyols (x), optionally at least one catalyst, and optionally at least one solvent in a flask, and adding one or more polyisocyanates (y) .

Since the reaction is easy to control, step 2) is preferable.

The reaction temperature in the case of using the catalyst is preferably less than 100 占 폚, more preferably 85 to 95 占 폚. When the reaction temperature is 100 ° C or higher, it is difficult to control the reaction rate and the cross-linking structure, and it may be difficult to produce the polyurethane polyol (A) having a desired molecular weight.

The reaction temperature in the case where the catalyst is not used is preferably 100 占 폚 or higher, more preferably 110 占 폚 or higher. The reaction time when the catalyst is not used is preferably 3 hours or more.

The weight average molecular weight (Mw) of the polyurethane polyol (A) is preferably 10,000 to 500,000, more preferably 30,000 to 400,000, and particularly preferably 50,000 to 350,000. Since the Mw of the polyurethane polyol (A) is in an appropriate range, it is easy to obtain a good coating property.

(Polyfunctional isocyanate compound (B))

As the polyfunctional isocyanate compound (B), known compounds can be used, and the compound (y) exemplified as the polyisocyanate (y) which is a raw material of the polyurethane polyol (A) (specifically, an aromatic polyisocyanate, an aliphatic polyisocyanate, Isocyanate, alicyclic polyisocyanate, and their trimethylolpropane duct / burette / trimer) can be used.

(Plasticizer (P))

And the wettability can be improved, so that the pressure-sensitive adhesive of the present invention can further include at least one plasticizer (P). The plasticizer (P) is not particularly limited, and fatty acid esters having 10 to 30 carbon atoms and the like are preferable from the viewpoint of compatibility with other components and the like.

Examples of the fatty acid ester having 10 to 30 carbon atoms include esters of a monobasic acid or a polybasic acid having a carbon number of 6 to 18 and a branched alcohol having a carbon number of 18 or less, esters of an unsaturated fatty acid or a branched acid having a carbon number of 14 to 18 with an alcohol having not more than 4 Esters of monobasic acids or polybasic acids having 6 to 18 carbon atoms with polyalkylene glycols, and the like.

Examples of the ester of a monobasic acid or a polybasic acid having 6 to 18 carbon atoms and a branched alcohol having 18 or less carbon atoms include isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, Isostearyl isostearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trimellitic acid trioleyl, trimellitic triisocetyl, and the like.

Examples of the unsaturated fatty acid or branched acid having 14 to 18 carbon atoms include misteryl oleic acid, oleic acid, linolic acid, linolenic acid, isopalmitic acid and isostearic acid. Examples of the alcohols having 4 or less valence include ethylene glycol, propylene glycol, glycerin, trimethylol propane, pentaerythritol, sorbitan and the like.

Examples of the ester of a monobasic acid or a polybasic acid having 6 to 18 carbon atoms with a polyalkylene glycol include polyethylene glycol such as dioctyl acid polyethylene glycol, di-2-ethylhexyl acid polyethylene glycol, polyethylene glycol dilaurylate, polyethylene glycol dioleate, Polyethylene glycol methyl ether, and the like.

Among them, as the plasticizer (P), one or more EO groups (in the molecule) may be used as the plasticizer (P) because the above effect (the effect of improving the releasability of the adhesive layer and the effect of improving the coating property when placed in a high temperature and high humidity environment) Group). The EO group is preferably 1 to 20, more preferably 4 to 14, and particularly preferably 6 to 8 from the viewpoints of re-release property and coating property. Examples of the plasticizer having an EO group include polyethylene glycol fatty acid diesters such as polyethylene glycol di-2-ethylhexanoate and the like.

The number average molecular weight (Mn) of the fatty acid ester is not particularly limited and is preferably from 300 to 1000, more preferably from 400 to 900, and particularly preferably from 500 to 850 from the standpoint of improvement of the wetting speed and the like.

(solvent)

The pressure-sensitive adhesive of the present invention may contain at least one solvent as required. As the solvent, known solvents can be used, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. From the viewpoints of the solubility of the polyurethane polyol (A) and the boiling point of the solvent, ethyl acetate, toluene and the like are particularly preferable.

(Other optional components)

The pressure-sensitive adhesive of the present invention may contain one or more other optional components as necessary insofar as the effect of the present invention is not impaired. Examples of other optional components include a catalyst, a resin other than the urethane resin, a filler, a metal powder, a pigment, a foil, a softener, a conductive agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a surface lubricant, A heat stabilizer, a polymerization inhibitor, a defoaming agent, and a lubricant.

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

Examples of the antioxidant include a radical chain inhibitor such as a phenol-based antioxidant and an amine-based antioxidant; Sulfur-based antioxidants, and phosphorus-based antioxidants.

As the phenol-based antioxidant,

Di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and stearin- Butyl-4-hydroxyphenyl) propionate;

(4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl- Butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), and 3,9-bis [1,1- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane; Methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [ (3'-hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, and 1,3,5-tris (3 ', 5'- Benzyl) -S-triazine-2,4,6- (1H, 3H, 5H) trione, and tocophenol; 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 antioxidant include triphenyl phosphite, diphenyl isodecyl phosphite, and phenyl diisodecyl phosphite.

Examples of the ultraviolet absorber include benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, salicylic acid ultraviolet absorbers, oxalanilide ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, and triazine ultraviolet absorbers.

Examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2- Oxybenzophenone, 2,2'-dihydroxy-4-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy- -Sulfobenzophenone, and bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane.

Examples of the benzotriazole ultraviolet absorber include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole , 2 - (2'-hydroxy-3 ', 5'-di-tert-butyl) Phenyl) benzotriazole, 2- (2'-hydroxy-4'-octociphenyl) benzotriazole, 2- [2'- , 6 '', - tetrahydropyrimidemethyl) -5'-methylphenyl] benzotriazole, 2,2'methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- -Benzotriazol-2-yl) phenol], and 2 (2'-hydroxy-5'-methacryloxyphenyl) -2H-benzotriazole.

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

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

Examples of the light stabilizer include hindered amine light stabilizers and ultraviolet light stabilizers.

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

Examples of the ultraviolet stabilizer include nickel bis (octylphenyl) sulfide, [2,2'-thiobis (4-tert-octylphenolato)] n-butylamine nickel, nickel complex-3,5-di- 4-hydroxybenzyl-phosphoric acid monoethylate, nickel-dibutyldithiocarbamate, benzoate type quencer, and nickel-dibutyldithiocarbamate.

Examples of the leveling agent include acrylic leveling agents, fluorine leveling agents, and silicone leveling agents. As the acrylic leveling agent, Polyflow No.36, Polyflow No.56, Polyflow No. 85HF, Polyflow No.99C (all manufactured by Kyoka Kagaku Co., Ltd.) can be listed. Examples of the fluorine leveling agent include Megapac F470N and Megafac F556 (both manufactured by DIC). As the silicone leveling agent, Grandyd PC4100 (manufactured by DIC) can be mentioned.

(Mixing ratio)

The pressure-sensitive adhesive of the present invention contains at least one polyurethane polyol (A) and at least one polyfunctional isocyanate compound (B) as essential components, and further includes at least one plasticizer (P) as required. These compounding ratios are not particularly limited, but preferable mixing ratios are as follows.

The amount of the at least one polyfunctional isocyanate (B) relative to 100 parts by mass of the at least one polyurethane polyol (A) is preferably 1 to 20 parts by mass, more preferably 5 to 15 parts by mass. If the amount of the at least one polyfunctional isocyanate (B) is too small, the cohesive force of the pressure-sensitive adhesive may be insufficient, and if it is too much, the adhesive force may become insufficient.

The amount of the at least one plasticizer (P) relative to 100 parts by mass of the at least one polyurethane polyol (A) is preferably 10 to 70 parts by mass, more preferably 20 to 50 parts by mass. If the amount of one or more plasticizers is too small, the addition effect (wetting property improving effect) of the plasticizer (P) can not be effectively exhibited. If the amount is too large, The amount of the urethane polyol (A) is only relatively small.

[Adhesive sheet]

The pressure-sensitive adhesive sheet of the present invention comprises a base sheet and an adhesive layer composed of the above-mentioned 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. Further, the release sheet is peeled off when the adhesive sheet is adhered to the adherend.

Fig. 1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to a 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 adhesive sheet 10 is a one-sided adhesive sheet having an adhesive layer formed on one side of a base sheet.

2 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to a second embodiment of the present invention. 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, metal foil and the like. The substrate sheet may be a laminated sheet in which any one or more layers are laminated on at least one side of these substrate sheets. The side of the substrate sheet on which the adhesive layer is formed may be subjected to a simple adhesive treatment such as corona discharge treatment and application of an anchor coating agent if necessary.

The constituent resin of the resin sheet is not particularly limited, and examples thereof include ester resins such as polyethylene terephthalate (PET); Olefin resins such as polyethylene (PE) and polypropylene (PP); Vinyl-based resins such as polyvinyl chloride; Amide resins such as nylon 66; Urethane resin (including foam); And combinations thereof.

The thickness of the resin sheet excluding the polyurethane sheet is not particularly limited, and is preferably 15 to 300 占 퐉. The thickness of the polyurethane sheet (including the foam) is not particularly limited, and is preferably 20 to 50,000 mu m.

The paper is not particularly limited, and examples thereof include ordinary paper, coated paper, and art paper.

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 on which a known release treatment has been carried out, such as application of a release agent to the surface of a resin sheet or paper, can be used.

The pressure-sensitive adhesive sheet can be produced by a known method.

First, the pressure-sensitive adhesive of the present invention is coated on the surface of the substrate sheet to form a coated layer of the pressure-sensitive adhesive of the present invention. As a coating method, known methods can be applied, and examples thereof 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.

Then, the coating layer is dried and cured to form an adhesive layer made of the cured product of the pressure-sensitive adhesive of the present invention. The heating and drying temperature is not particularly limited, and is preferably about 60 to 150 ° C. The thickness of the adhesive layer (thickness after drying) varies depending on the use, but is preferably 0.1 to 200 占 퐉.

Subsequently, if necessary, the release sheet is attached to the exposed surface of the adhesive layer by a known method.

As described above, a pressure sensitive adhesive sheet on one side can be produced.

The double-sided pressure-sensitive adhesive sheet can be produced by carrying out the above operation on both sides.

Contrary to the above method, the pressure-sensitive adhesive of the present invention is coated on the surface of the release sheet to form a coated layer made of the pressure-sensitive adhesive of the present invention, and then the coated layer is dried and cured to obtain a pressure- And finally, the base sheet may be laminated on the exposed surface of the adhesive layer.

(Usage)

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 protective sheet, a cosmetic sheet, and a non-slip sheet.

A flat panel display such as a liquid crystal display (LCD) and an organic electroluminescence display (ELD), and a touch panel display in which a related flat panel display and a touch panel are combined, is used for a TV, a personal computer (PC) And is widely used in electronic devices such as information terminals.

The pressure-sensitive adhesive sheet of the present invention is suitably used as a surface protective sheet such as a flat panel display and a touch panel display, and substrates and optical members manufactured or used in their manufacturing process.

The use range of the electronic device has been expanded, and there is a possibility that the electronic device is placed under a harsh high temperature and high humidity environment.

The pressure-sensitive adhesive sheet of the present invention has good tackiness and can have good re-peelability even if it is placed under a high-temperature and high-humidity environment which is more severe than the conventional one.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good re-peelability even under a harsh high temperature and high humidity environment, and a pressure-sensitive adhesive sheet using the same.

Example

Hereinafter, Synthesis Examples, Examples related to the present invention, and Comparative Examples will be described. Unless specifically stated otherwise in the following description, "part" means "part by mass" and "%" means "% by mass".

[Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)] [

The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured by gel permeation chromatography (GPC). The measurement conditions were as follows. Further, both Mw and Mn are values in terms of polystyrene.

<Measurement Conditions>

Device: SHIMADZU Prominence (manufactured by Shimadzu Corporation)

Column: Three SHODEX LF-804 (manufactured by Showa Denko K.K.) are connected in series,

Detector: Parallax refraction index detector,

Solvent: tetrahydrofuran (THF),

Flow rate: 0.5 mL / min,

Solvent temperature: 40 DEG C,

Sample concentration: 0.1%

Sample injection amount: 100 μL

[material]

The materials used are as follows.

<Bifunctional polyether polyol (x1) having EO group>

(x1-1): triethylene glycol, Mn150, hydroxyl number 2 ("triethylene glycol" available from Mitsubishi Chemical Corporation),

(x1-2): polyethylene glycol (PEG), Mn200, hydroxyl number 2 ("PEG-200", product of Tohoku Kakuko).

(x1-3): polyethylene glycol (PEG), Mn400, hydroxyl number 2 ("PEG-400" manufactured by Tohokakakuko Co., Ltd.)

(x1-4): polyethylene glycol (PEG), Mn1000, hydroxyl number 2 ("PEG-1000" manufactured by Tohokakakuko Co., Ltd.)

(x1-5): polyethylene glycol (PEG), Mn2000, hydroxyl number 2 ("PEG-2000", product of Tohoku Kakuko Co., Ltd.)

(x1-6): polyethylene glycol (PEG), Mn4000, hydroxyl number 2 ("PEG-4000", product of Tohoku Kakuko Co., Ltd.)

(x1-7): polyethylene glycol (PEG), Mn6000, hydroxyl number 2 ("PEG-6000" manufactured by Tohoku Kagakuko Co., Ltd.)

(x1-8): polyoxyethylene polyoxypropylene block polymer, Mn1200, hydroxyl number 2 ("Efan 450" manufactured by Daicel Chemical Industries, Ltd.)

(x1-9): EO adduct of propylene glycol (PG), Mn4000, hydroxyl number 2 ("Exenol 510" manufactured by Asahi-Chochi).

<Trifunctional Polyether Polyol (x2) Having EO Group>

(x2-1): glycerin PO.EO adduct (glycerin polypropylene glycol end-modified ethylene glycol), Mn3000, hydroxyl number 3 (Adeka polyether AM-302 from ADEKA)

(x2-2): glycerin PO.EO adduct (glycerin polypropylene glycol end-ethylene glycol modification), Mn5000, hydroxyl number 3 (Adeka polyether AM-502 from ADEKA).

<Bifunctional polyether polyol (x3) having no EO group>

(x3-1): polyoxypropylene glycol, Mn4000, hydroxyl number 2 (Sannix PP-4000 manufactured by Sanyo Chemical Industries, Ltd.).

<Trifunctional Polyether Polyol (x4) Having No EO Group>

(x4-1): polyoxypropylene glyceryl ether, Mn1500, hydroxyl number 3 ("Sanix GP-1500" manufactured by Sanyo Chemical Industries, Ltd.).

<Bifunctional polyester polyol (x5) having no EO group>

(x5-1): Adipic acid / 3-methyl-1,5-pentanediol condensate, Mn1000, hydroxyl number 2 (Kurare Polyol P-1010, manufactured by Kuraray Co.).

&Lt; Polyisocyanate (y) >

(y-1): 1,6-hexamethylene diisocyanate ("Desmodur H" manufactured by Toso Co., Ltd.)

(y-2): 1,3-xylylene diisocyanate ("Takenate 500" manufactured by Mitsui Chemicals, Inc.).

&Lt; The polyfunctional isocyanate compound (B) >

(B-1) hexamethylene diisocyanate / isocyanurate ("Sumidur N-3300" manufactured by Sumika Bayer Urethane Co., Ltd.)

(B-2) hexamethylene diisocyanate / trimethylol propane duct (Coronate HL manufactured by Toso Co., Ltd.),

(B-3) Trilendiisocyanate / trimethylolpropane duct (Coronate L manufactured by Tosoh Corporation).

&Lt; Plasticizer (P) >

(P-1): Polyetherester compound (polyethylene glycol (Mw300) di-2-ethylhexanoate, EO group number: average 6 ("Adekaizer RS700"

(P-2): polyetherester compound (polyethylene glycol) (Mw600) di-2-ethylhexanoate EO group number: average 12.8 (Adekaizer RS735 manufactured by ADEKA)

(P-3): Polyethylene glycol fatty acid ester (dioleate PEG-8), EO number: 8 (Pegnol 24-O, product of Tohokagakuko).

(P-4): isopropyl myristate, and no EO group ("NIKKOL IPM-100" manufactured by Nikko Chemicals Co., Ltd.).

[Synthesis Example of Polyurethane Polyol]

(Synthesis Example 1)

 In a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer and a dropping funnel, 1 part of a bifunctional polyether polyol (x1-1) having an EO group and 1 part of a trifunctional polyether polyol having an EO group (x2-1) are prepared. 170 parts of toluene, 0.03 part of dibutyltin dilaurate as a catalyst and 0.01 part of 2-ethylhexanoate tin were added to the prepared solution. After gradually raising the temperature to 90 占 폚 in a nitrogen atmosphere, a polyisocyanate (y-1) having an NCO / OH ratio (functional group ratio) of 0.6 (5.7 parts) was dropped into the flask. After completion of the dropwise addition, the reaction was carried out for 2 hours. After disappearance of the remaining isocyanate group was confirmed by infrared absorption (IR) spectrum, the reaction solution was cooled to terminate the reaction.

Thus, a solution (nonvolatile matter: 60%) of the polyurethane polyol (A-1) was obtained. The Mw of the obtained polyurethane polyol (A-1) was 122,000.

Table 1-1 shows the kinds of raw polyols and raw polyisocyanates used, the blending ratio thereof, and the Mw of the obtained polyurethane polyol (A-1).

In Tables 1-1 to 1-3, the unit of the blending amount of the polyols (x1) to (x5) is [parts]. The blending amount of the polyisocyanate (y) is represented by the NCO / OH ratio (functional group ratio).

The calculation method of the amount (parts) of the polyisocyanate (y-1) is as follows.

(number of units of (y-1)) [parts] = (NCO / OH ratio) x (molecular weight of (y-1)) / (X2-1) / (x2-1) / (x2-1) / (x2-1) / (x2-1) Number of hydroxyl groups)])

= 0.6 x 168/2 x (1/150 x 2 + 99/3000 x 3)

? 5.7

(Synthesis Examples 2 to 21)

In Synthesis Examples 2 to 21, the polyurethane polyol (A-1) was obtained in the same manner as in Synthesis Example 1, except that the kind of raw polyol used and the raw polyisocyanate and the blending ratio thereof were changed as shown in Tables 1-1 to 1-3, 2) to (A-19) and (D-1) to (D-2). In each of the synthesis examples, Mw of the obtained polyurethane polyol is shown in Tables 1-1 to 1-3.

(Synthesis Example 22)

64 parts of polyether polyol (x3-1) and 36 parts of polyether polyol (x4-1) were blended and stirred with a disper to obtain polyol blend product (D-3).

Tables 1-3 show the kinds of raw polyols used, blending ratios thereof, and Mw of the resulting polyol blend (D-3).

(Example 1)

100 parts of polyurethane polyol (A-1) obtained in Synthesis Example 1, 30 parts of plasticizer (P-1), 0.5 part of antioxidant (IRGANOX L 135 from BASF), 8 parts of polyfunctional isocyanate compound And 100 parts of ethyl acetate as a solvent were mixed and stirred with a disper to obtain a urethane pressure-sensitive adhesive. The amount of each material except the solvent represents the nonvolatile matter conversion value.

Table 2-1 shows the kinds of materials used and blending ratio.

As a substrate sheet, a polyethylene terephthalate (PET) sheet ("Lumirror T-60" manufactured by Torayi Co., Ltd., thickness: 50 μm) was prepared. The resulting urethane pressure-sensitive adhesive was applied to one side of the substrate sheet using a Comma Coater (registered trademark) at a coating speed of 3 m / min and dried to a thickness of 12 탆. Thereafter, evaluation of coating properties was performed.

Next, the formed coating layer was dried at 100 캜 for 2 minutes to form a pressure-sensitive adhesive layer. A release sheet (SUPERSTEC SP-PET38 manufactured by LINTEX Co., Ltd.) having a thickness of 38 mu m was stuck onto the adhesive layer to obtain a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet thus obtained was cured for 1 week under conditions of 23 ° C-50% RH, and then evaluated for adhesion and re-release properties.

(Examples 2 to 19 and Comparative Examples 1 and 2)

In Examples 2 to 19 and Comparative Examples 1 and 2, a urethane pressure-sensitive adhesive and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1, except that the kinds of the materials used and the blending ratios were changed as shown in Tables 2-1 to 2-3. .

Evaluation of coatability was carried out when the coat layer was formed in the same manner as in Example 1. [

The pressure-sensitive adhesive sheet thus obtained was cured for 1 week under conditions of 23 ° C-50% RH as in Example 1, and then evaluated for adhesion and re-release properties.

(Comparative Example 3)

100 parts of the polyol blend (D-3) obtained in Synthesis Example 22, 44 parts of the polyfunctional isocyanate compound (B-3), 0.04 parts of Nacem ferric (Nippon Kayaku Co., Ltd.) as a catalyst, And 266 parts of ethyl acetate as a solvent were mixed and stirred with a disper to obtain an urethane pressure-sensitive adhesive. The amount of each material other than the solvent represents the nonvolatile matter conversion value. Table 2-3 shows the kinds of materials used and blending ratios.

A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive was used to change the drying temperature of the coating layer to 130 캜.

As in the case of Example 1, evaluation of coatability was carried out when the coat layer was formed.

The obtained pressure-sensitive adhesive sheet was cured for one week under the conditions of 23 占 폚 -50% RH, and then evaluated for adhesion and re-releasability in the same manner as in Example 1. [

[Evaluation Items and Evaluation Methods]

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

(Coating property)

The surface of the coating layer was visually observed and evaluated based on the following criteria.

<Criteria>

(Good): The coated surface was smooth.

△ (Possible): Pottery stains were found on the coated surface to such an extent that practically no trouble occurred.

× (Not applicable): Roll marks or deformations were observed on the coated surface.

(adhesiveness)

Two test pieces (pieces) having a width of 25 mm and a length of 100 mm were cut out from the adhesive sheet. The peel sheet was peeled off from each of the two test pieces under an atmosphere of 23 ° C to 50% RH, and a caustic soda glass plate was attached to the surface of the exposed adhesive layer and pressed with a 2 kg roll.

One of the two stacked sheets thus obtained was allowed to stand in an atmosphere of 23 ° C-50% RH for 24 hours (temperature and humidity condition 1).

The other laminate was taken out of the oven and allowed to air in an atmosphere of 23 ° C to 50% RH for 1 hour after being left in an oven at 85 ° C to 85% RH for 72 hours (temperature and humidity condition 2).

The adhesive strength of each laminate was measured on the basis of JIS Z 0237 using a tensile tester under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180, and evaluated based on the following criteria.

<Criteria>

○ (Good): less than 20 mN / 25 mm

△ (possible): 20 to 100 mN / 25 mm

× (not allowed): exceeding 100mN / 25mm

(Re-peelability)

Three test specimens having a width of 70 mm and a length of 100 mm were cut out from the adhesive sheet. The peel sheet was peeled off from each of the three test pieces under an atmosphere of 23 ° C to 50% RH, and a caustic soda glass plate was attached to the surface of the exposed adhesive layer and pressed with a laminator.

The obtained three laminated bodies were each placed in an oven set at 40 ° C-90% RH (temperature and humidity condition 1), 60 ° C-90% RH (temperature and humidity condition 2) and 85 ° C and 85% RH .

Three laminated bodies were taken out of the oven and air-cooled for 1 hour in an atmosphere of 23 ° C-50% RH, and then the adhesive sheet was peeled off from the glass plate to evaluate re-peelability. The surface of the glass plate on which the adhesive sheet was stuck in the dark room was irradiated with LED lamp light and observed with eyes and evaluated according to the following criteria.

 <Criteria>

(Good): No adhesion of the adhesive layer component to the glass surface can be seen.

△ (Possible): Attachment of a thin adhesive layer component can be seen at one or two places of the glass surface.

× (not applicable): Adhesion of a thin adhesive layer can be seen at three or more places on the glass surface. Or adhesion of a thick adhesive layer component to one or two places of the glass surface can be seen.

[Evaluation results]

The evaluation results are shown in Tables 2-1 to 2-3.

In Examples 1 to 19,

(X) containing at least one bifunctional polyether polyol (x1) having an EO group and at least one trifunctional polyether polyol (x2) having an EO group, and at least one polyisocyanate (y) A polyurethane polyol (A) which is a reaction product,

A urethane pressure-sensitive adhesive containing a polyfunctional isocyanate compound (B) was prepared.

All of the urethane pressure-sensitive adhesives obtained in Examples 1 to 19 were good or comparatively good.

All of the pressure-sensitive adhesive sheets obtained in Examples 1 to 19 exhibited good or relatively good adhesive strength even under the conditions of 23 ° C-50% RH (temperature and humidity condition 1) and 85 ° C-85% RH (temperature and humidity condition 2).

All of the pressure-sensitive adhesive sheets obtained in Examples 1 to 19 were all of 40 ° C-90% RH (temperature and humidity condition 1), 60 ° C-90% RH (temperature and humidity condition 2), and 85 ° C- Also in the test conditions, re-peeling property was good or comparatively good.

Especially,

When the total amount of the at least one bifunctional polyether polyol (x1) and the at least one trifunctional polyether polyol (x2) is 100 parts by mass, the amount of the at least one bifunctional polyether polyol (x1) , And the amount of the at least one trifunctional polyether polyol (x2) is 99 to 70 parts by mass,

The bifunctional polyether polyol (x1) has an Mn of 200 to 4,000,

Bifunctional polyether polyol (x1) In Examples 2 to 5, 10 to 14 and 18 in which a urethane pressure-sensitive adhesive containing PEG was prepared, better results than those of the other examples were obtained.

In addition, the pressure-sensitive adhesive sheets obtained in Examples 1 to 18 using the plasticizer (P) having an EO group were able to obtain better results than in Example 19 in which the plasticizer (P) was not used.

The pressure-sensitive adhesive sheet obtained in Comparative Example 1 using only the bifunctional polyether polyol (x4) having no EO group and the bifunctional polyester polyol (x5) having no EO group as the raw material polyol for the polyurethane polyol had an 85 ° C-85% RH The re-peelability was poor in the test conditions of temperature and humidity condition 3).

The pressure-sensitive adhesive sheet obtained in Comparative Example 2 using only the trifunctional polyether polyol (x2) having an EO group as the raw material polyol of the polyurethane polyol had poor peelability in the test conditions of 85 ° C-85% RH (temperature and humidity condition 3) .

The pressure-sensitive adhesive obtained in Comparative Example 3 using a blend of a bifunctional polyether polyol (x3) having no EO group and a bifunctional polyether polyol (x4) having no EO group in place of the polyurethane polyol had poor coatability.

The pressure-sensitive adhesive sheet obtained in Comparative Example 3 had poor adhesive strength even under the test conditions of 23 ° C-50% RH (temperature and humidity condition 1) and 85 ° C-85% RH (temperature and humidity condition 2).

In addition, the pressure-sensitive adhesive sheet obtained in Comparative Example 3 did not use the plasticizer (P), and thus the re-peelability was good or relatively good under the test conditions of 85 ° C-85% RH (temperature and humidity condition 3).

[Table 1-1]

[Table 1-2]

[Table 1-3]

[Table 2-1]

[Table 2-2]

[Table 2-3]

The present invention is not limited to the above-described embodiments and examples, and appropriate design changes are possible without departing from the gist of the present invention.

The present application claims priority based on Japanese Patent Application No. 2016-14898, filed on July 29, 2016, and incorporates all such disclosures therein.

10,20; Adhesive sheet
11, 21; Substrate sheet
12, 22A, 22B; Adhesive layer
13, 23A, 23B; Peeling sheet

Claims (7)

(X2) having at least one bifunctional polyether polyol (x1) having at least one ethyleneoxy group in a molecule and at least one trifunctional polyether polyol (x2) having at least one ethyleneoxy group in a molecule, (A) which is a copolymerization reaction product of a polyisocyanate (x) and at least one polyisocyanate (y)
A pressure-sensitive adhesive comprising a polyfunctional isocyanate compound (B).
The method according to claim 1,
A pressure-sensitive adhesive further comprising a plasticizer (P).
3. The method of claim 2,
Wherein the plasticizer (P) has at least one ethyleneoxy group in one molecule.
4. The method according to any one of claims 1 to 3,
When the total amount of the at least one bifunctional polyether polyol (x1) and the at least one trifunctional polyether polyol (x2) is 100 parts by mass, the amount of the at least one bifunctional polyether polyol (x1) , And the amount of the at least one trifunctional polyether polyol (x2) is 99 to 70 parts by weight.
5. The method according to any one of claims 1 to 4,
Wherein the bifunctional polyether polyol (x1) has a number average molecular weight of 200 to 4,000.
6. The method according to any one of claims 1 to 5,
Wherein the at least one bifunctional polyether polyol (x1) comprises polyethylene glycol.
A pressure-sensitive adhesive sheet comprising a base sheet and an adhesive layer comprising a cured product of the pressure-sensitive adhesive according to any one of claims 1 to 6.

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