WO2018020803A1 - Adhesive agent and adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive agent which can form an adhesive layer having better re-peelability than in the prior art even when the adhesive agent is put in a harsh, high-temperature, and high-humidity environment. The adhesive agent according to the present invention contains: a polyurethane polyol (A) which is a copolymerization reaction product between one or more polyisocyanates (y) and a plurality of polyols (x) including one or more bifunctional polyether polyols (x1) having one or more ethyleneoxy (EO) groups in one molecule and one or more trifunctional polyether polyols (x2) having one or more ethyleneoxy (EO) groups in one molecule; and a polyfunctional isocyanate compound (B).

Description

Adhesive and adhesive sheet

The present invention relates to an adhesive and an adhesive sheet.

Conventionally, pressure-sensitive adhesive sheets in which a pressure-sensitive adhesive layer is formed on a substrate sheet have been widely used as surface protection sheets for various members. As the pressure-sensitive adhesive, there are mainly acrylic pressure-sensitive adhesive and urethane-based pressure-sensitive adhesive. Acrylic pressure-sensitive adhesives are excellent in adhesive strength, but because of their strong adhesive strength, re-peelability after being attached to an adherend is not good. In particular, after aging in a high-temperature and high-humidity environment, re-peelability is further reduced due to an increase in adhesive force, and adherend contamination that tends to cause the adhesive to remain on the surface of the adherend after re-peeling tends to occur. . On the other hand, the urethane-based pressure-sensitive adhesive has appropriate adhesiveness to the adherend, and has excellent removability while having good adhesion to the adherend.

Patent Document 1 discloses a urethane-based pressure-sensitive adhesive in which a polyfunctional isocyanate compound is blended with a polyurethane polyol obtained by reacting a polyester polyol, a polyether polyol, and a polyisocyanate in the presence of two types of catalysts. (Claim 1). It is described that this urethane-based pressure-sensitive adhesive has good re-peelability after being left to stand at 40 ° C.-65% RH after being stuck to an adherend (the implementation of Paragraph 0051 and Table 2). Examples 1-6 etc.).
In this specification, unless otherwise specified, “RH” indicates relative humidity.

Patent Document 2 discloses a urethane-based pressure-sensitive adhesive containing 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-based pressure-sensitive adhesive has good re-peelability after being adhered to an adherend and left for 24 hours under conditions of 40 ° C. and 80% RH (paragraph 0049 and table 1). Examples 1 to 4 etc.).

Patent Document 3 discloses a urethane-based pressure-sensitive adhesive containing 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). It is described that this urethane-based pressure-sensitive adhesive has good removability after being allowed to stand for 96 hours under conditions of 60 ° C.-90% RH after being attached to an adherend (paragraph 0061 and Table 1). Examples 1 to 18 etc.).

In addition, there is Patent Document 4 as a related document of the present invention. The description of this document will be described later.

JP 2000-73040 A JP 2011-190420 A Japanese Patent Laying-Open No. 2015-7226 Japanese Patent Laying-Open No. 2015-151429

Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescence displays (ELDs), and touch panel displays that combine such flat panel displays and touch panels include televisions (TVs), personal computers (PCs), mobile phones, And widely used in electronic devices such as portable information terminals.
A urethane type adhesive sheet is used suitably as surface protection sheets, such as a flat panel display and a touch panel display, and the board | substrate and optical member which are manufactured or used by these manufacturing processes.
The range of use of the electronic device is expanding, and there is a possibility that the electronic device is placed in a severer high-temperature and high-humidity environment.

The present invention has been made in view of the above circumstances, and a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good removability even when placed in a severer high-temperature and high-humidity environment than before, and It aims at providing the adhesive sheet using this.

The pressure-sensitive adhesive of the present invention is
One or more bifunctional polyether polyols (x1) having one or more ethyleneoxy (EO) groups in one molecule and one or more 3 having one or more ethyleneoxy (EO) groups in one molecule A polyurethane polyol (A) which is a copolymerization reaction product of a plurality of types of polyols (x) containing a functional polyether polyol (x2) and one or more types of polyisocyanates (y);
And a polyfunctional isocyanate compound (B).

The pressure-sensitive adhesive of the present invention is a composition in which a plurality of types of materials including the above components (A) and (B) are blended. In the pressure-sensitive adhesive, a plurality of types of blending components including the components (A) and (B). May not all be clearly present as independent components. That is, the pressure-sensitive adhesive of the present invention may contain a reaction product obtained by partially reacting a plurality of blended components including components (A) and (B).

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.
Generally, a sheet-like material is referred to as “tape”, “film”, or “sheet” depending on the thickness and width. In the present specification, these are not particularly distinguished, and the term “sheet” is used as a term representing a concept encompassing them.

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

According to the present invention, a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good removability even when placed in a severer high-temperature and high-humidity environment than before, and a pressure-sensitive adhesive sheet using the same are provided. can do.

It is a schematic cross section of the adhesive sheet of 1st Embodiment which concerns on this invention. It is a schematic cross section of the adhesive sheet of 2nd Embodiment which concerns on this invention.

"Adhesive"
The pressure-sensitive adhesive of the present invention is
One or more bifunctional polyether polyols (x1) having one or more ethyleneoxy (EO) groups in one molecule and one or more 3 having one or more ethyleneoxy (EO) groups in one molecule A polyurethane polyol (A) which is a copolymerization reaction product of a plurality of types of polyols (x) containing a functional polyether polyol (x2) and one or more types of polyisocyanates (y);
And a polyfunctional isocyanate compound (B).

(Polyurethane polyol (A))
The polyurethane polyol (A) is a reaction product obtained by copolymerizing a plurality of types of polyols (x) and one or more types of polyisocyanates (y). One or more polyurethane polyols (A) can be used. The copolymerization reaction can be performed in the presence of a catalyst, if necessary. A solvent can be used in the copolymerization reaction as necessary.

<Polyol (x)>
The plural kinds of polyols (x) are at least one or more bifunctional polyether polyols (x1) having one or more EO groups in one molecule and one having one or more EO groups in one molecule. A tri- or higher functional polyether polyol (x2).
As long as the effects of the present invention are not impaired, the plurality of polyols (x) can contain one or more other polyether polyols in accordance with the polyether polyols (x1) and (x2).

Known polyether polyols can be used. Examples of polyether polyols include compounds obtained by addition polymerization of one or more oxirane compounds using an active hydrogen-containing compound having two or more active hydrogens in one molecule as an initiator. .

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, xylylenediamine, etc. 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); tetrahydrofuran (THF) and the like.

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

As described above, in the present invention, as the plurality of kinds of polyol (x), at least one kind of bifunctional polyether polyol (x1) having one or more EO groups in one molecule and one molecule. One or more trifunctional polyether polyols (x2) having one or more EO groups are used.

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

Furthermore, since the polyether polyols (x1) and (x2) both have an EO group, the following effects can be obtained.
Generally, when a structure with a pressure-sensitive adhesive sheet attached to an adherend is exposed to a high-temperature and high-humidity environment, the re-peelability decreases due to an increase in the adhesive strength of the pressure-sensitive adhesive layer, and the surface of the adherend after re-peeling In some cases, the adherend remains with the adhesive remaining on the surface.
The pressure-sensitive adhesive of the present invention using a bifunctional polyether polyol (x1) having an EO group and a trifunctional polyether polyol (x2) having an EO group as a raw material polyol (x) of the polyurethane polyol (A) has been conventionally used. Even when placed in a severer high-temperature and high-humidity environment, an adhesive layer having good removability can be formed. In order to show this, in the section “Examples” below, the temperature and humidity conditions for re-peelability evaluation are set more severely than those in Patent Documents 1 to 3 listed in the “Background Art” section.

The mechanism of the above effect is not necessarily clear, but the present inventors presume as follows.
In general, since a decrease in the removability of the pressure-sensitive adhesive layer is not observed in a high temperature drying environment, it is assumed that the decrease in the removability of the pressure-sensitive adhesive layer is due to moisture. 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), the hydrophilicity of the adhesive layer is improved. As a result, moisture transfer between the adhesive layer and the external environment is likely to occur, and even if moisture enters the adhesive layer from the outside, moisture is easily discharged from the adhesive layer to the external environment. It is presumed that the amount of water could be kept relatively low and was less susceptible to moisture.

Moreover, in the adhesive of this invention using 2 types of polyether polyols (x1) and (x2) which have EO group as raw material polyol (x) of a polyurethane polyol (A), the improvement effect of coatability is also acquired. . Although the mechanism of this effect is not necessarily clear, the present inventors presume as follows.
By using two kinds of polyether polyols (x1) and (x2) having an EO group as the raw material polyol (x), the hardness of the polyurethane polyol (A) can be improved. As a result, it is speculated that coating unevenness such as roll streaks and distortion can be suppressed, and a coating film having good surface smoothness can be formed.
The coating film with improved hardness is less susceptible to the effects of drying air and the like in the drying and curing processes and can maintain good surface smoothness. Therefore, according to the present invention, an adhesive layer with high surface smoothness can be formed.

The bifunctional polyether polyol (x1) is a compound (addition polymer) obtained by addition polymerization of one or more oxirane compounds containing ethylene oxide (EO) to the above bifunctional initiator. Among these, polyalkylene glycols obtained by addition polymerization of one or more alkylene oxides (AO) containing ethylene oxide (EO) to the above bifunctional initiator are preferable. The higher the EO group content in the polyalkylene glycol, the better. Since the content of EO groups is large, polyethylene glycol (PEG) is particularly preferable as the bifunctional polyether polyol (x1). That is, it is preferable that 1 or more types of bifunctional polyether polyol (x1) contains PEG.

The number average molecular weight (Mn) of the bifunctional polyether polyol (x1) is not particularly limited, and the above-mentioned effects (improvement effect of the releasability of the adhesive layer when placed in a high temperature and high humidity environment and improvement of the coating property) (Effect) is effectively exhibited, and is preferably 150 to 6,000, more preferably 200 to 4,000, and particularly preferably 200 to 2,000.

Trifunctional polyether polyol (x2) is a compound (addition polymer) obtained by addition polymerization of one or more oxirane compounds containing ethylene oxide (EO) to the above trifunctional initiator. Especially, the compound (addition polymer) obtained by addition-polymerizing 1 or more types of alkylene oxide (AO) containing ethylene oxide (EO) to said trifunctional initiator is preferable.

From the viewpoint of reactivity with the bifunctional polyether polyol (x1), the trifunctional polyether polyol (x2) preferably has an EO group at least at the terminal. As trifunctional polyether polyol (x2) having an EO group at least at its terminal, glycerin EO adduct obtained by addition polymerization of one or more ethylene oxides (EO) to glycerin, one or more propylene oxides (PO) ) And one or more ethylene oxide (EO) in this order, and a glycerin PO · EO adduct (also referred to as “glycerin polypropylene glycol-terminated ethylene glycol-modified”) obtained by addition polymerization.

The number average molecular weight (Mn) of the trifunctional polyether polyol (x2) is not particularly limited, and the above-mentioned effects (improvement of removability of the adhesive layer when placed in a high temperature and high humidity environment and improvement of coating properties) (Effect) is effectively exhibited, and is preferably 200 to 6,000, more preferably 400 to 5,000, and particularly preferably 1,000 to 4,000.

From the viewpoint of the balance between cohesive strength and adhesive strength,
When the total amount of one or more bifunctional polyether polyols (x1) and one or more trifunctional polyether polyols (x2) is 100 parts by mass,
More preferably, the amount of the one or more bifunctional polyether polyols (x1) is 1 to 40 parts by mass, and the amount of the one or more trifunctional polyether polyols (x2) is 99 to 60 parts by mass,
More preferably, the amount of the one or more bifunctional polyether polyols (x1) is 1 to 30 parts by mass, and the amount of the one or more trifunctional polyether polyols (x2) is 99 to 70 parts by mass,
More preferably, the amount of the one or more bifunctional polyether polyols (x1) is 5 to 15 parts by mass, and the amount of the one or more trifunctional polyether polyols (x2) is 95 to 85 parts by mass.

As a related document of the present invention, there is Patent Document 4 listed in the section “Background Art”. This document discloses a urethane-based pressure-sensitive adhesive containing a polyurethane prepolymer and a carboxylic acid ester, wherein the carboxylic acid ester satisfies at least one of the following (Condition A) and (Condition B) (Claim 1).
(Condition A) Carboxylic acid ester contains an ether bond in the molecule.
(Condition B) Carboxylic acid ester contains 31 or more carbon atoms in one molecule.
In the [Example] section of Patent Document 4, a pressure-sensitive adhesive using a polyol having an EO group is produced. However, unlike the present invention, the polyol used in the [Example] section of Patent Document 4 is only a trifunctional polyether polyol (specifically, a glycerin PO / EO adduct) (Table 3). Although the evaluation of the removability of the pressure-sensitive adhesive layer has not been made in the section “Example” of Patent Document 4, the present inventors have found that the pressure-sensitive adhesive of the present invention has a higher temperature than the pressure-sensitive adhesive described in Patent Document 4. It has been found that the releasability of the pressure-sensitive adhesive layer after being stored in a high humidity environment is excellent (see the section [Example] and Comparative Example 2).

Other polyether polyols used as necessary as the raw material polyol (x) are a bifunctional polyether polyol (x3) having no EO group, a trifunctional polyether polyol (x4) having no EO group, or It is a tetra- or higher functional polyether polyol.

As long as the effects of the present invention are not impaired, the raw material polyol (x) is a plurality of types of polyethers including one or more types of bifunctional polyether polyols (x1) and one or more types of trifunctional polyether polyols (x2). Depending on the polyol, one or more polyester polyols can be included.
Known polyester polyols can be used. Examples of the polyester polyol include a compound (esterified product) obtained by an esterification reaction of at least one polyol component and at least one acid component.

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, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, and hexanetriol Etc.

The raw acid components include succinic acid, methyl succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1, 4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid , And acid anhydrides thereof.

In addition to the above, as the polyester polyol, a compound obtained by ring-opening polymerization of one or more lactones such as polycaprolactone, poly (β-methyl-γ-valerolactone), and polyvalerolactone (ring-opening polymer) ).

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 be insufficient.

<Polyisocyanate (y)>
A well-known thing can be used as a polyisocyanate compound (y), and aromatic polyisocyanate, aliphatic polyisocyanate, araliphatic polyisocyanate, alicyclic polyisocyanate, etc. are mentioned.

Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate. 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 and the like.

Aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2 4,4-trimethylhexamethylene diisocyanate and the like.

The aromatic aliphatic polyisocyanates include ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene, 1 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, and the like.

The alicyclic polyisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4. -Cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatemethyl) cyclohexane, 1,4-bis (isocyanatemethyl) cyclohexane, etc. .

Other examples of the polyisocyanate include trimethylolpropane adducts, burettes, and trimers of the above polyisocyanates (this trimer includes an isocyanurate ring).

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

<Catalyst>
Known catalysts can be used as the catalyst, and examples thereof include tertiary amine compounds and organometallic compounds.

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

Examples of organometallic compounds include tin compounds and non-tin compounds.
Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate , Triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.
Non-tin compounds include titanium-based compounds such as dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride; lead-based compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; 2 -Iron systems such as iron ethylhexanoate and iron acetylacetonate; cobalt systems such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc systems such as zinc naphthenate and zinc 2-ethylhexanoate; zirconium naphthenate, etc. Zirconium type is mentioned.

One or more catalysts can be used.
When the reactivity of each of the plural types of polyols (x) used in combination is different, there is a possibility that gelation or reaction solution white turbidity easily occurs in a single catalyst system due to the difference in reactivity. In this case, by using two types of catalysts, it is easy to control the reaction (for example, reaction rate and the like), and the above problem can be solved. That is, in the present invention, it is preferable to use two types of catalysts. A combination of two kinds of catalysts is not particularly limited, and examples thereof include tertiary amine / organometallic, tin / non-tin, and tin / tin. Preferred are tin / tin, more preferably dibutyltin dilaurate and tin 2-ethylhexanoate.
The mass ratio of tin 2-ethylhexanoate to dibutyltin dilaurate (tin 2-ethylhexanoate / dibutyltin dilaurate) is not particularly limited and is preferably more than 0 and less than 1, more preferably 0.2 to 0.6. is there. If the mass ratio is 1 or more, the balance of the catalyst activity is not good, and there is a possibility that gelation tends to occur.

The amount of the one or more catalysts used is not particularly limited, and is preferably 0.01 to 1.0% by mass with respect to the total amount of the plurality of types of polyols (x) and one or more types of polyisocyanates (y). It is.

<Solvent>
For the polymerization of the polyurethane polyol (A), one or more solvents can be used as necessary. A well-known thing can be used as a solvent, Methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, etc. are mentioned. From the viewpoint of the solubility of the polyurethane polyol (A) and the boiling point of the solvent, ethyl acetate, toluene and the like are particularly preferable.

<Polymerization method>
The polymerization method of the polyurethane polyol (A) is not particularly limited, and known polymerization methods such as a bulk polymerization method and a solution polymerization method can be applied.
The polymerization procedure is not particularly limited,
Procedure 1) Procedure for charging a plurality of types of polyol (x), one or more types of polyisocyanate (y), one or more types of catalysts as required, and one or more types of solvents as needed into a flask at once;
Procedure 2) Charge a plurality of types of polyol (x), one or more types of catalysts as required, and one or more types of solvents as needed, and add one or more types of polyisocyanate (y) dropwise thereto. The procedure to do is mentioned.
Procedure 2) is preferred because the reaction is easy to control.

The reaction temperature when using a catalyst is preferably less than 100 ° C., more preferably 85 to 95 ° C. When the reaction temperature is 100 ° C. or higher, it is difficult to control the reaction rate and the crosslinked structure, and it may be difficult to produce the polyurethane polyol (A) 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. The reaction time when no catalyst is 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. Good coatability is easily obtained when the Mw of the polyurethane polyol (A) is in an appropriate range.

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

(Plasticizer (P))
Since the wettability can be improved, the pressure-sensitive adhesive of the present invention can further contain one or more plasticizers (P). The plasticizer (P) is not particularly limited, and fatty acid esters having 10 to 30 carbon atoms are preferable from the viewpoint of compatibility with other components.

Examples of the fatty acid ester having 10 to 30 carbon atoms include esters of monobasic acids or polybasic acids having 6 to 18 carbon atoms and branched alcohols having 18 or less carbon atoms, unsaturated fatty acids or branched acids having 14 to 18 carbon atoms, and 4 Examples thereof include esters with lower-valent alcohols and esters of monobasic acids or polybasic acids having 6 to 18 carbon atoms with polyalkylene glycols.

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

Examples of the unsaturated fatty acid having 14 to 18 carbon atoms or branched acid include myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, and isostearic acid. Examples of the tetravalent or lower alcohol include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitan.

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

Among them, the above-mentioned effects (improvement effect of removability of adhesive layer and improvement effect of coating property when placed in high temperature and high humidity environment) are effectively expressed, so as a plasticizer (P), Those having one or more EO groups in one molecule are preferred. From the viewpoint of removability and coatability, the number of EO groups is preferably 1 to 20, more preferably 4 to 14, and particularly preferably 6 to 8. Examples of the plasticizer having an EO group include polyethylene glycol fatty acid diesters such as polyethylene glycol di-2-ethylhexanoate.

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

(solvent)
The pressure-sensitive adhesive of the present invention can contain one or more solvents as required. A well-known thing can be used as a solvent, Methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, etc. are mentioned. From the viewpoints of the solubility of the polyurethane polyol (A) and the boiling point of the solvent, ethyl acetate and toluene are particularly preferable.

(Other optional ingredients)
The pressure-sensitive adhesive of the present invention can contain one or more other optional components as necessary, as long as the effects of the present invention are not impaired. Other optional components include catalysts, resins other than urethane resins, fillers, metal powders, pigments, foils, softeners, conductive agents, antioxidants, UV absorbers, light stabilizers, surface lubrication Agents, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, antifoaming agents, and lubricants.

充填 Examples of fillers include talc, calcium carbonate, and titanium oxide.

Examples of the antioxidant include radical chain inhibitors such as phenol-based antioxidants and amine-based antioxidants; peroxide decomposing agents such as sulfur-based antioxidants and phosphorus-based antioxidants.

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

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

Examples of phosphorus antioxidants include triphenyl phosphite, diphenyl isodecyl phosphite, and phenyl diisodecyl phosphite.

Examples of UV absorbers include benzophenone UV absorbers, benzotriazole UV absorbers, salicylic acid UV absorbers, oxalic anilide UV absorbers, cyanoacrylate UV absorbers, and triazine UV absorbers. .

Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, and 2,2′-dihydroxy. -4-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, and bis (2-methoxy-4-hydroxy-5-benzoylphenyl) Examples include methane.

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

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

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

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

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

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

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

(Mixing ratio)
The pressure-sensitive adhesive of the present invention contains one or more polyurethane polyols (A) and one or more polyfunctional isocyanate compounds (B) as essential components, and further contains one or more plasticizers (P) as necessary. . These mixing ratios are not particularly limited, but preferable mixing ratios are as follows.

The amount of the one or more polyfunctional isocyanates (B) with respect to 100 parts by mass of the one or more polyurethane polyols (A) is preferably 1 to 20 parts by mass, more preferably 5 to 15 parts by mass. If the amount of the one or more polyfunctional isocyanate (B) is too small, the cohesive force of the pressure-sensitive adhesive may be insufficient, and if it is excessive, the adhesive force may be insufficient.

The amount of the one or more plasticizers (P) with respect to 100 parts by mass of the one or more polyurethane polyols (A) is preferably 10 to 70 parts by mass, more preferably 20 to 50 parts by mass. If the amount of the one or more plasticizers (P) is too small, the effect of adding the plasticizer (P) (improvement of wettability) cannot be expressed effectively. If the amount is too large, improvement of the addition effect commensurate with the amount added cannot be expected. The amount of the polyurethane polyol (A), which is the main active ingredient of the pressure-sensitive adhesive originally necessary, is only relatively reduced.

[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. An adhesion layer can be formed in the single side | surface or both surfaces of a base material sheet. If necessary, the exposed surface of the adhesive layer can be covered with a release sheet. The release sheet is peeled off when the pressure-sensitive adhesive sheet is attached to the adherend.

In FIG. 1, the schematic cross section of the adhesive sheet of 1st Embodiment which concerns on this invention is shown. In FIG. 1, reference numeral 10 is an adhesive sheet, reference numeral 11 is a base sheet, reference numeral 12 is an adhesive layer, and reference numeral 13 is 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.
In FIG. 2, the schematic cross section of the adhesive sheet of 2nd Embodiment which concerns on this invention is shown. In FIG. 2, reference numeral 20 is an adhesive sheet, reference numeral 21 is a base material sheet, reference numerals 22A and 22B are adhesive layers, and reference numerals 23A and 23B are 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 laminated on at least one surface of these base sheets. The surface of the base sheet on the side where the adhesive layer is to be formed may be subjected to easy adhesion treatment such as corona discharge treatment and anchor coating agent application, if necessary.

There are no particular restrictions on the constituent resin of the resin sheet, ester resins such as polyethylene terephthalate (PET); olefin resins such as polyethylene (PE) and polypropylene (PP); vinyl resins such as polyvinyl chloride; nylon 66, etc. Amide resin; 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 μm. The thickness of the polyurethane sheet (including foam) is not particularly limited, and is preferably 20 to 50,000 μm.
The paper is not particularly limited, and examples thereof include plain 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 in which a known release treatment such as application of a release agent is performed on the surface of a resin sheet or paper can be used.

An adhesive sheet can be manufactured by a well-known method.
First, the pressure-sensitive adhesive of the present invention is applied to the surface of the base sheet to form a coating layer made of the pressure-sensitive adhesive of the present invention. A known method can be applied as the coating method, 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.
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 of the adhesive layer (thickness after drying) varies depending on the use, 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.
A single-sided adhesive sheet can be manufactured as described above.
A double-sided PSA sheet can be produced by performing the above operations on both sides.

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 made of the pressure-sensitive adhesive of the present invention, and then the coating layer is dried and cured to produce the pressure-sensitive adhesive of the present invention. An adhesive layer made of a cured product of the agent may be formed, and finally a substrate sheet may be laminated on the exposed surface of the adhesive layer.

(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 and the like. The pressure-sensitive adhesive sheet of the present invention is suitably used as a surface protective sheet, a cosmetic sheet, a non-slip sheet, and the like.
Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescence displays (ELDs), and touch panel displays that combine such flat panel displays and touch panels include televisions (TVs), personal computers (PCs), mobile phones, And widely used in electronic devices such as portable information terminals.
The pressure-sensitive adhesive sheet of the present invention is suitably used as a surface protection sheet for flat panel displays, touch panel displays, and substrates and optical members manufactured or used in these manufacturing processes.
The range of use of the electronic device is expanding, and there is a possibility that the electronic device is placed in a severer high-temperature and high-humidity environment.
The pressure-sensitive adhesive sheet of the present invention is preferable because it has good pressure-sensitive adhesive properties and can have good removability even when placed in a severer high-temperature and high-humidity environment than before.

As described above, according to the present invention, a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good removability even when placed in a severer high-temperature and high-humidity environment than before, and The used adhesive sheet can be provided.

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

[Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)]
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) method. The measurement conditions were as follows. Mw and Mn are both polystyrene equivalent values.
<Measurement conditions>
Apparatus: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: 3 SHODEX LF-804 (made by Showa Denko KK) connected in series,
Detector: differential refractive index detector,
Solvent: tetrahydrofuran (THF),
Flow rate: 0.5 mL / min,
Solvent temperature: 40 ° C.
Sample concentration: 0.1%
Sample injection volume: 100 μL.

[material]
The materials used are as follows.
<Bifunctional polyether polyol having EO group (x1)>
(X1-1): triethylene glycol, Mn 150, hydroxyl number 2 (“Triethylene glycol” manufactured by Mitsubishi Chemical Corporation),
(X1-2): polyethylene glycol (PEG), Mn200, hydroxyl number 2 (“PEG-200” manufactured by Toho Chemical Industry Co., Ltd.),
(X1-3): polyethylene glycol (PEG), Mn400, hydroxyl number 2 (“PEG-400” manufactured by Toho Chemical Industry Co., Ltd.),
(X1-4): polyethylene glycol (PEG), Mn1000, hydroxyl number 2 (“PEG-1000” manufactured by Toho Chemical Industry Co., Ltd.),
(X1-5): polyethylene glycol (PEG), Mn2000, hydroxyl number 2 (“PEG-2000” manufactured by Toho Chemical Industry Co., Ltd.),
(X1-6): polyethylene glycol (PEG), Mn 4000, hydroxyl number 2 (“PEG-4000” manufactured by Toho Chemical Industry Co., Ltd.),
(X1-7): polyethylene glycol (PEG), Mn 6000, hydroxyl number 2 (“PEG-6000” manufactured by Toho Chemical Industry Co., Ltd.),
(X1-8): polyoxyethylene polyoxypropylene block polymer, Mn 1200, hydroxyl number 2 (Daiichi Kogyo Seiyaku “Epan 450”),
(X1-9): EO adduct of propylene glycol (PG), Mn 4000, hydroxyl number 2 (“Exenol 510” manufactured by Asahi Glass Co., Ltd.).

<Trifunctional polyether polyol having EO group (x2)>
(X2-1): Glycerin PO · EO adduct (glycerin polypropylene glycol-terminated ethylene glycol modified), Mn 3000, hydroxyl number 3 (“ADEKA Polyether AM-302” manufactured by ADEKA),
(X2-2): Glycerin PO · EO adduct (glycerin polypropylene glycol-terminated ethylene glycol modified), Mn 5000, hydroxyl number 3 (“ADEKA Polyether AM-502” manufactured by ADEKA).

<Bifunctional polyether polyol having no EO group (x3)>
(X3-1): polyoxypropylene glycol, Mn4000, hydroxyl number 2 (“Sanix PP-4000” manufactured by Sanyo Chemical Industries).

<Trifunctional polyether polyol having no EO group (x4)>
(X4-1): polyoxypropylene glyceryl ether, Mn 1500, hydroxyl group number 3 (“Sanix GP-1500” manufactured by Sanyo Chemical Industries).

<Bifunctional polyester polyol having no EO group (x5)>
(X5-1): adipic acid / 3-methyl-1,5-pentanediol condensate, Mn1000, hydroxyl number 2 (“Kuraray polyol P-1010” manufactured by Kuraray)

<Polyisocyanate (y)>
(Y-1): 1,6-hexamethylene diisocyanate (“Desmodur H” manufactured by Tosoh Corporation),
(Y-2): 1,3-xylylene diisocyanate (“Takenate 500” manufactured by Mitsui Chemicals, Inc.).

<Polyfunctional isocyanate compound (B)>
(B-1) Hexamethylene diisocyanate / isocyanurate (“Sumijour N-3300” manufactured by Sumika Bayer Urethane Co., Ltd.)
(B-2) hexamethylene diisocyanate / trimethylolpropane adduct (“Coronate HL” manufactured by Tosoh Corporation),
(B-3) Tolylene diisocyanate / trimethylolpropane adduct (“Coronate L” manufactured by Tosoh Corporation).

<Plasticizer (P)>
(P-1): polyether ester compound (polyethylene glycol (Mw300) di-2-ethylhexanoate), EO group number: average 6 (“ADEKA Sizer RS700” manufactured by ADEKA),
(P-2): polyether ester compound (polyethylene glycol (Mw600) di-2-ethylhexanoate), EO group number: 12.8 on average (“ADEKA Sizer RS735” manufactured by ADEKA),
(P-3): polyethylene glycol fatty acid ester (PEGylate PEG-8), number of EO groups: 8 on average (“Pegnol 24-O” manufactured by Toho Chemical Industry Co., Ltd.),
(P-4): Isopropyl myristate, EO group-free (“NIKKOL IPM-100” manufactured by Nikko Chemicals).

[Synthesis example of polyurethane polyol]
(Synthesis Example 1)
In a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 1 part of bifunctional polyether polyol (x1-1) having EO group and trifunctional having EO group 99 parts of polyether polyol (x2-1) was charged. To this charged solution, 170 parts of toluene, 0.03 part of dibutyltin dilaurate and 0.01 part of tin 2-ethylhexanoate as a catalyst were added. After gradually raising the temperature to 90 ° C. in a nitrogen atmosphere, an amount (5.7 parts) of polyisocyanate (y-1) that gives an NCO / OH ratio (functional group ratio) of 0.6 is dropped into the flask. did. Reaction was performed for 2 hours after completion | finish of dripping. After confirming the disappearance of the remaining isocyanate group by infrared absorption (IR) spectrum, the reaction solution was cooled to complete the reaction.
As described above, a solution (nonvolatile content: 60%) of the polyurethane polyol (A-1) was obtained. Mw of the obtained polyurethane polyol (A-1) was 122,000.

Table 1-1 shows the types of the raw material polyol and the polyisocyanate 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 polyols (x1) to (x5) is [parts]. Moreover, the compounding quantity of polyisocyanate (y) is shown by NCO / OH ratio (functional group ratio).

The method for calculating the amount of polyisocyanate (y-1) is as follows.
(Part of (y-1)) [parts] =
(NCO / OH ratio) × (molecular weight of (y-1)) / (number of NCO groups of (y-1)) ×
[(Part of (x1-1)) / (molecular weight of (x1-1)) × (number of hydroxyl groups of (x1-1))
+ (Part of (x2-1)) / (molecular weight of (x2-1)) × (number of hydroxyl groups of (x2-1))]
= 0.6 × 168/2 × (1/150 × 2 + 99/3000 × 3)
≒ 5.7

(Synthesis Examples 2 to 21)
In Synthesis Examples 2 to 21, a polyurethane was prepared in the same manner as in Synthesis Example 1 except that the types of raw material polyols and polyisocyanates used and the blending ratios thereof were changed as shown in Tables 1-1 to 1-3. Polyols (A-2) to (A-19) and (D-1) to (D-2) were obtained. In each synthesis example, Mw of the obtained polyurethane polyol is shown in Table 1-1 to Table 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 a polyol blend (D-3).
Table 1-3 shows the types of raw material polyols used, their blending ratios, and the Mw of the obtained polyol blend (D-3).

Example 1
100 parts of the polyurethane polyol (A-1) obtained in Synthesis Example 1, 30 parts of a plasticizer (P-1), 0.5 part of an antioxidant (“IRGANOX L 135” manufactured by BASF), a polyfunctional isocyanate compound ( B-1) 8 parts and 100 parts 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 except a solvent shows a non-volatile content conversion value.
Table 2-1 shows the types and mixing ratios of the materials used.

A polyethylene terephthalate (PET) sheet (“Lumirror T-60” manufactured by Toray Industries Inc., thickness 50 μm) was prepared as a base material sheet. Using a comma coater (registered trademark), the obtained urethane-based pressure-sensitive adhesive was coated on one side of the base sheet so that the coating speed was 3 m / min and the thickness after drying was 12 μm. Thereafter, the coatability was evaluated.
Next, the formed coating layer was dried at 100 ° C. for 2 minutes to form an adhesive layer. On this adhesive layer, a 38 μm-thick release sheet (“Supertech SP-PET38” manufactured by Lintec) was attached to obtain an adhesive sheet. The obtained pressure-sensitive adhesive sheet was cured for 1 week under the condition of 23 ° C.-50% RH, and then subjected to evaluation of adhesive strength and removability.

(Examples 2 to 19, Comparative Examples 1 and 2)
In Examples 2 to 19 and Comparative Examples 1 and 2, the urethane type was changed in the same manner as in Example 1 except that the types and blending ratios of the materials used were changed as shown in Tables 2-1 to 2-3. An adhesive and an adhesive sheet were obtained.
As in Example 1, when the coating layer was formed, the coating property was evaluated.
Further, as in Example 1, the obtained pressure-sensitive adhesive sheet was cured for 1 week under the condition of 23 ° C.-50% RH, and then subjected to evaluation of adhesive strength and removability.

(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 part of Nersem Ferric Acid (Nippon Chemical Industry Co., Ltd.) as a catalyst, and 266 parts of ethyl acetate as a diluent solvent was blended and stirred with a disper to obtain a urethane-based pressure-sensitive adhesive. In addition, the usage-amount of each material other than a solvent shows a non-volatile content conversion value. Table 2-3 shows the types and compounding ratios of the materials used.
Using the obtained pressure-sensitive adhesive, a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the drying temperature of the coating layer was 130 ° C.
As in Example 1, when the coating layer was formed, the coating property was evaluated.
Further, as in Example 1, the obtained pressure-sensitive adhesive sheet was cured for 1 week under the condition of 23 ° C.-50% RH, and then subjected to evaluation of adhesive strength and removability.

[Evaluation items and methods]
Evaluation items and evaluation methods of the pressure-sensitive adhesive and 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.
Δ (possible): Coating unevenness to the extent that there was no practical problem on the coated surface was observed.
X (impossible): Roll streaks or distortion was observed on the coated surface.

(Adhesive force)
Two test pieces having a width of 25 mm and a length of 100 mm were cut out from the adhesive sheet. For each of the two test pieces, the release sheet was peeled off in an atmosphere of 23 ° C.-50% RH, a caustic soda glass plate was attached to the exposed surface of the pressure-sensitive adhesive layer, and pressed with a 2 kg roll.
One of the obtained two laminates was left for 24 hours in an atmosphere of 23 ° C.-50% RH (temperature and humidity condition 1).
The other laminate was left in an oven at 85 ° C.-85% RH for 72 hours (temperature / humidity condition 2), then removed from the oven and air-cooled in an atmosphere at 23 ° C.-50% RH for 1 hour.
About each laminated body, based on JISZ0237, the adhesive force was measured on conditions with a peeling speed of 300 mm / min and a peeling angle of 180 ° using a tensile tester, and evaluated based on the following criteria.
<Criteria>
○ (Good): Less than 20 mN / 25 mm.
Δ (possible): 20 to 100 mN / 25 mm.
X (impossible): More than 100 mN / 25 mm.

(Removability)
Three test pieces having a width of 70 mm and a length of 100 mm were cut out from the adhesive sheet. For each of the three test pieces, the release sheet was peeled off in an atmosphere of 23 ° C.-50% RH, a caustic soda glass plate was attached to the exposed surface of the adhesive layer, and pressure-bonded with a laminator.
The obtained three laminates were respectively 40 ° C.-90% RH (temperature / humidity condition 1), 60 ° C.-90% RH (temperature / humidity condition 2), and 85 ° C.-85% RH (temperature / humidity condition 3). It was left in the set oven for 72 hours.
Each of the three laminates was taken out of the oven and air-cooled in an atmosphere of 23 ° C.-50% RH for 1 hour, and then the pressure-sensitive adhesive sheet was peeled off from the glass plate to evaluate the removability. The surface of the glass plate on the side where the adhesive sheet was pasted in the dark room was irradiated with LED lamp light, and the following criteria were evaluated by visual observation.
<Criteria>
○ (good): No adhesion layer component is observed on the glass surface.
Δ (possible): Adhesion of a thin adhesive layer component is observed at one or two places on the glass surface.
X (impossible): The adhesion of the thin adhesion layer component is seen in three or more places on the glass surface. Alternatively, a thick adhesion layer component adheres to one or two places on the glass surface.

[Evaluation results]
The evaluation results are shown in Tables 2-1 to 2-3.
In Examples 1 to 19,
A plurality of polyols (x) including one or more bifunctional polyether polyols (x1) having an EO group and one or more trifunctional polyether polyols (x2) having an EO group, and one or more poly Polyurethane polyol (A) which is a copolymerization reaction product with isocyanate (y),
A urethane-based pressure-sensitive adhesive containing the polyfunctional isocyanate compound (B) was produced.

All of the urethane pressure-sensitive adhesives obtained in Examples 1 to 19 had good or relatively good coatability.
The pressure-sensitive adhesive sheets obtained in Examples 1 to 19 were all adhesive under any of the test conditions of 23 ° C.-50% RH (temperature / humidity condition 1) and 85 ° C.-85% RH (temperature / humidity condition 2). Was good or relatively good.
All of the pressure-sensitive adhesive sheets obtained in Examples 1 to 19 were 40 ° C.-90% RH (temperature / humidity condition 1), 60 ° C.-90% RH (temperature / humidity condition 2), and 85 ° C.-85% RH (temperature Under any of the test conditions of humidity condition 3), the removability was good or relatively good.

In particular,
When the total amount of the one or more bifunctional polyether polyols (x1) and the one or more trifunctional polyether polyols (x2) is 100 parts by mass, the one or more bifunctional polyether polyols (x1) The amount is 1 to 30 parts by mass, and the amount of one or more trifunctional polyether polyols (x2) is 99 to 70 parts by mass,
Mn of the bifunctional polyether polyol (x1) is 200 to 4,000,
In Examples 2 to 5, 10 to 14, and 18 in which the bifunctional polyether polyol (x1) produced a urethane-based pressure-sensitive adhesive containing PEG, better results were obtained than in the other examples.
Furthermore, the pressure-sensitive adhesive sheets obtained in Examples 1 to 18 using the plasticizer (P) having an EO group gave better results than Example 19 in which the plasticizer (P) was not used.

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

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 was subjected to the test conditions of 85 ° C. to 85% RH (temperature and humidity condition 3). The removability was poor.

Adhesion obtained in Comparative Example 3 using a blend of a bifunctional polyether polyol (x3) having no EO group and a trifunctional polyether polyol (x4) having no EO group instead of the polyurethane polyol The agent had poor coatability.
The pressure-sensitive adhesive sheet obtained in Comparative Example 3 had poor adhesive strength under both test conditions of 23 ° C.-50% RH (temperature / humidity condition 1) and 85 ° C.-85% RH (temperature / humidity condition 2). It was.
Since the pressure-sensitive adhesive sheet obtained in Comparative Example 3 did not use a plasticizer (P), the removability was good or relatively good under the test conditions of 85 ° C.-85% RH (temperature / humidity condition 3). there were.

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

This application claims priority based on Japanese Patent Application No. 2016-149988 filed on July 29, 2016, the entire disclosure of which is incorporated herein.

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

Claims (7)

1. One or more bifunctional polyether polyols (x1) having one or more ethyleneoxy groups in one molecule and one or more trifunctional polyether polyols (x2) having one or more ethyleneoxy groups in one molecule Polyurethane polyol (A) which is a copolymerization reaction product of a plurality of types of polyol (x) and one or more types of polyisocyanate (y),
   A pressure-sensitive adhesive comprising a polyfunctional isocyanate compound (B).
2. The pressure-sensitive adhesive according to claim 1, further comprising a plasticizer (P).
3. The pressure-sensitive adhesive according to claim 2, wherein the plasticizer (P) has one or more ethyleneoxy groups in one molecule.
4. When the total amount of the one or more bifunctional polyether polyols (x1) and the one or more trifunctional polyether polyols (x2) is 100 parts by mass, the one or more bifunctional polyether polyols (x1) The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the amount is 1 to 30 parts by mass and the amount of one or more trifunctional polyether polyols (x2) is 99 to 70 parts by mass.
5. The pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the number average molecular weight of the bifunctional polyether polyol (x1) is 200 to 4,000.
6. The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the one or more bifunctional polyether polyol (x1) comprises polyethylene glycol.
7. A pressure-sensitive adhesive sheet comprising a base sheet and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive according to any one of claims 1 to 6.

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