CN109476975B

CN109476975B - Adhesive and adhesive sheet

Info

Publication number: CN109476975B
Application number: CN201780043861.XA
Authority: CN
Inventors: 田邉慎吾; 佐藤武志
Original assignee: Toyo Ink SC Holdings Co Ltd; Toyochem Co Ltd
Current assignee: Toyochem Co Ltd; Artience Co Ltd
Priority date: 2016-07-29
Filing date: 2017-05-24
Publication date: 2020-07-24
Anticipated expiration: 2037-05-24
Also published as: TWI725188B; KR101995437B1; JP6098750B1; CN109476975A; JP2018016755A; KR20190003768A; TW201809202A; WO2018020803A1

Abstract

The invention provides an adhesive and an adhesive sheet, which can form an adhesive layer with good re-peeling performance even under a severer high-temperature and high-humidity environment than before. The adhesive of the present invention comprises a polyurethane polyol (a) which is a copolymerization reaction product of one or more polyisocyanates (x) and one or more polyisocyanates (y), wherein the polyurethane polyol (a) is a copolymerization reaction product of one or more 2-functional polyether polyols (x1) having one or more Ethyleneoxy (EO) groups in one molecule and one or more 3-functional polyether polyols (x2) having one or more Ethyleneoxy (EO) groups in one molecule.

Description

Adhesive and adhesive sheet

This application claims priority based on Japanese patent application No. 2016-.

Technical Field

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

Background

An adhesive sheet having an adhesive layer formed on a base sheet has been widely used as a surface protection sheet for various members since now. As the adhesive, an acrylic adhesive and a urethane adhesive are mainly used. The acrylic pressure-sensitive adhesive has excellent adhesive force, but has poor removability after being stuck to an adherend because of its strong adhesive force. In particular, after a lapse of time under a high-temperature and high-humidity environment, the removability further decreases due to an increase in adhesive force, and there is a tendency that the adherend is easily contaminated by the adhesive remaining on the surface of the adherend after removability. In contrast, the urethane adhesive has a moderate adhesiveness to an adherend, has good adhesion to the adherend, and is relatively excellent in removability.

Patent document 1 discloses a urethane adhesive obtained by blending a polyfunctional isocyanate compound into a polyurethane polyol obtained by reacting a polyester polyol and a polyether polyol with a polyisocyanate in the presence of two catalysts (claim 1). It is described that the urethane adhesive has good removability after being placed under a condition of 40 to 65% RH after being attached to an adherend (paragraph 0051, examples 1 to 6 in table 2, and the like).

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

Patent document 2 discloses a urethane adhesive containing a polyurethane polyol, a polyfunctional isocyanate compound, and a fatty acid ester having 1 to 30 carbon atoms (claim 1). It is described that the urethane adhesive has good removability after being left for 24 hours under 40 to 80% RH after being attached to an adherend (paragraph 0049, examples 1 to 4 in table 1, and the like).

Patent document 3 discloses a urethane 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 the urethane adhesive has good removability after being left for 96 hours under a condition of 60 to 90% RH after being attached to an adherend (paragraph 0061 and examples 1 to 18 in table 1).

Patent document 4 is a related document of the present invention. The contents of the description of the above document will be described later.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2000-73040

Patent document 2: japanese patent laid-open publication No. 2011-190420

Patent document 3: japanese patent laid-open publication No. 2015-7226

Patent document 4: japanese patent laid-open publication No. 2015-151429

Disclosure of Invention

Problems to be solved by the invention

Flat panel displays (flat panel displays) such as liquid Crystal displays (L acquired Crystal displays, L CD) and organic Electroluminescence displays (E L D), and touch panel displays in which the flat panel displays and touch panels are combined are widely used in electronic devices such as Televisions (TVs), Personal Computers (PCs), mobile phones, and portable information terminals.

The urethane adhesive sheet is suitably used as a surface protective sheet for flat panel displays, touch panel displays, substrates and optical members produced or used in the production process thereof.

The electronic device has a wider range of use and may be placed in a more severe high-temperature and high-humidity environment than before.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive agent capable of forming an adhesive layer having good removability even when placed in a severer high-temperature and high-humidity environment than before, and an adhesive sheet using the same.

Means for solving the problems

The adhesive of the present invention comprises:

a polyurethane polyol (a) which is a copolymerization reaction product of a plurality of polyols (x) comprising one or more 2-functional polyether polyols (x1) having one or more Ethyleneoxy (EO) groups in one molecule and one or more 3-functional polyether polyols (x2) having one or more Ethyleneoxy (EO) groups in one molecule, and one or more polyisocyanates (y); and

a polyfunctional isocyanate compound (B).

The adhesive of the present invention is a composition in which a plurality of materials including the component (a) and the component (B) are blended, but in some cases, the plurality of blended components including the component (a) and the component (B) are not all definitely present as independent components in the adhesive. That is, the adhesive of the present invention may contain a reaction product obtained by reacting a part of a plurality of blend components including the component (a) and the component (B).

The adhesive sheet of the present invention comprises a substrate sheet and an adhesive layer containing a cured product of the adhesive of the present invention.

In general, a sheet is called a "tape", "film", or "sheet" in terms of thickness and width. In the present specification, the term "sheet" is used as a term indicating a concept including these terms, without particularly distinguishing these terms.

In the present specification, unless otherwise specified, "molecular weight" refers to a number average molecular weight (Mn). "Mn" is a polystyrene-equivalent number average molecular weight determined by Gel Permeation Chromatography (GPC).

ADVANTAGEOUS EFFECTS OF INVENTION

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

Drawings

Fig. 1 is a schematic cross-sectional view of an adhesive sheet according to embodiment 1 of the present invention.

Fig. 2 is a schematic cross-sectional view of an adhesive sheet according to embodiment 2 of the present invention.

Description of the symbols

10. 20: an adhesive sheet;

11. 21: a substrate sheet;

12. 22A, 22B: an adhesive layer;

13. 23A, 23B: and (4) peeling off the sheet.

Detailed Description

Adhesive agent "

The adhesive of the present invention comprises:

a polyurethane polyol (a) which is a copolymerization reaction product of a plurality of polyols (x) comprising one or more 2-functional polyether polyols (x1) having one or more Ethyleneoxy (EO) groups in one molecule and one or more 3-functional polyether polyols (x2) having one or more Ethyleneoxy (EO) groups in one molecule, with one or more 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 polyols (x) with one or more polyisocyanates (y). One or more of the polyurethane polyols (A) may be used. The copolymerization reaction may be carried out in the presence of a catalyst, if necessary. A solvent may be used as necessary in the copolymerization reaction.

< polyol (x) >

The polyols (x) include at least one or more 2-functional polyether polyols (x1) having one or more EO groups in one molecule and one or more 3-functional polyether polyols (x2) having one or more EO groups in one molecule.

The plurality of polyols (x) may contain one or more other polyether polyols in addition to the polyether polyol (x1), polyether polyol (x2) within a range not impairing the effects of the present invention.

As the polyether polyol, known ones can be used. The polyether polyol includes a compound (addition polymer) obtained by addition polymerization of one or more ethylene oxide (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 hydroxyl group-containing compounds and amines. Specifically, there may be mentioned: 2-functional initiators such as Ethylene Glycol (EG), Propylene Glycol (PG), 1, 4-butanediol, neopentyl Glycol, butylethylpentanediol, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine; 3-functional initiators such as glycerin, trimethylolpropane, and triethanolamine; 4-functional initiators such as pentaerythritol, ethylenediamine, and aromatic diamines; 5-functional initiators such as diethylenetriamine, etc.

As the oxirane compound, there can be mentioned: alkylene Oxides (AO) such as Ethylene Oxide (EO), Propylene Oxide (PO), and Butylene Oxide (BO); tetrahydrofuran (THF), and the like.

The polyether polyol is preferably an alkylene oxide adduct of an active hydrogen-containing compound (also referred to as "polyoxyalkylene polyol"). Among them, 2-functional polyether polyols such as Polyethylene Glycol (PEG), polypropylene Glycol (PPG), and polytetramethylene Glycol are preferable; and 3-functional polyether polyols such as alkylene oxide adducts of glycerin.

As described above, in the present invention, at least one or more 2-functional polyether polyols (x1) having one or more EO groups in one molecule and one or more 3-functional polyether polyols (x2) having one or more EO groups in one molecule are used as the plurality of polyols (x).

The 2-functional polyether polyol (x1) has two-dimensional crosslinkability and can impart appropriate flexibility to the adhesive layer. The 3-functional polyether polyol (x2) has three-dimensional crosslinkability and can impart a moderate hardness to the adhesive layer. By using these components in combination, an adhesive layer having appropriate cohesive strength and adhesive force tends to be easily obtained.

Further, when both the polyether polyol (x1) and the polyether polyol (x2) have an EO group, the following effects can be obtained.

In general, when a structure in which an adhesive sheet is attached to an adherend is exposed to a high-temperature and high-humidity environment, the removability is reduced due to an increase in the adhesive force of the adhesive layer, and there is a case where contamination of the adherend occurs in which the adhesive remains on the surface of the adherend after removability.

The adhesive of the present invention using the 2-functional polyether polyol (x1) having an EO group and the 3-functional polyether polyol (x2) having an EO group as the raw material polyol (x) of the polyurethane polyol (a) can form an adhesive layer having good removability even when placed in a severer high-temperature and high-humidity environment than before. In order to show this, in the later-described [ example ], the temperature and humidity conditions for evaluation of removability are set to be severer than those of patent documents 1 to 3 listed in the "background art".

The mechanism of the action and effect is not necessarily clear, but the present inventors have assumed the following.

In general, since no decrease in the removability of the adhesive layer is observed in a high-temperature dry environment, it is estimated that the decrease in the removability of the adhesive layer is caused by moisture. By using two types of polyether polyol (x1) and polyether polyol (x2) having EO groups as the raw material polyol (x) of the polyurethane polyol (a), the hydrophilicity of the adhesive layer is improved. As a result, moisture is likely to migrate between the adhesive layer and the external environment, and it is presumed that even if moisture enters the adhesive layer from the outside, the moisture is likely to be discharged from the adhesive layer to the external environment, and the amount of moisture in the adhesive layer can be maintained relatively low, and is less likely to be affected by moisture.

Further, the adhesive of the present invention using two types of polyether polyol (x1) and polyether polyol (x2) having EO groups as the raw material polyol (x) of the polyurethane polyol (a) can also obtain an effect of improving coatability. The mechanism of the action and effect is not necessarily clear, but the present inventors have assumed the following.

By using two types of polyether polyol (x1) having EO groups and polyether polyol (x2) as the raw material polyol (x), the hardness of the polyurethane polyol (a) can be increased. As a result, coating unevenness such as roll marks and skew was suppressed, and it was estimated that a coating film having excellent surface smoothness could be formed.

The coating film having improved hardness is less susceptible to the influence of drying air or the like in the drying and curing steps, and can maintain good surface smoothness. Therefore, according to the present invention, an adhesive layer having high surface smoothness can be formed.

The 2-functional polyether polyol (x1) is a compound (addition polymer) obtained by addition polymerization of one or more ethylene oxide compounds containing Ethylene Oxide (EO) with the 2-functional initiator. Among them, polyalkylene glycols obtained by addition polymerization of one or more Alkylene Oxides (AO) containing Ethylene Oxide (EO) and the 2-functional initiator are preferable. The higher the EO group content in the polyalkylene glycol, the more preferable. The 2-functional polyether polyol (x1) is particularly preferably polyethylene glycol (PEG) since the EO group content is large. That is, the one or more 2-functional polyether polyols (x1) preferably comprise PEG.

The number average molecular weight (Mn) of the 2-functional polyether polyol (x1) is not particularly limited, but is preferably 150 to 6,000, more preferably 200 to 4,000, and particularly preferably 200 to 2,000, from the viewpoint of effectively exhibiting the above-described action effect (the effect of improving the removability and the coatability of the adhesive layer when exposed to a high-temperature and high-humidity environment).

The 3-functional polyether polyol (x2) is a compound (addition polymer) obtained by addition polymerization of one or more ethylene oxide compounds containing Ethylene Oxide (EO) with the 3-functional initiator. Among them, preferred is a compound (addition polymer) obtained by addition polymerization of one or more Alkylene Oxides (AO) containing Ethylene Oxide (EO) with the 3-functional initiator.

From the viewpoint of reactivity with the 2-functional polyether polyol (x1), the 3-functional polyether polyol (x2) preferably has an EO group at least at the end. Examples of the 3-functional polyether polyol (x2) having at least an EO group at the end include a glycerin EO adduct obtained by addition polymerization of glycerin with at least one Ethylene Oxide (EO), a glycerin PO — EO adduct obtained by addition polymerization of glycerin with at least one Propylene Oxide (PO) and at least one Ethylene Oxide (EO) in the stated order (also referred to as "glycerin polypropylene glycol end glycol modification"), and the like.

The number average molecular weight (Mn) of the 3-functional polyether polyol (x2) is not particularly limited, but is preferably 200 to 6,000, more preferably 400 to 5,000, and particularly preferably 1,000 to 4,000, from the viewpoint of effectively exhibiting the above-described action effect (the effect of improving the removability and the coatability of the adhesive layer when placed in a high-temperature and high-humidity environment).

From the viewpoint of the balance between the cohesive force and the adhesive force,

when the total amount of the one or more 2-functional polyether polyols (x1) and the one or more 3-functional polyether polyols (x2) is set to 100 parts by mass,

more preferably, the amount of the one or more 2-functional polyether polyols (x1) is 1 to 40 parts by mass, and the amount of the one or more 3-functional polyether polyols (x2) is 99 to 60 parts by mass,

more preferably, the amount of the one or more 2-functional polyether polyols (x1) is 1 to 30 parts by mass, and the amount of the one or more 3-functional polyether polyols (x2) is 99 to 70 parts by mass,

more preferably, the amount of the one or more 2-functional polyether polyols (x1) is 5 to 15 parts by mass, and the amount of the one or more 3-functional 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 "prior art". The document discloses a urethane adhesive which contains a prepolymer of polyurethane and a carboxylic acid ester, and the carboxylic acid ester satisfies at least one of the following conditions (a) and (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.

An adhesive using a polyol having an EO group is produced in [ example ] of patent document 4. However, unlike the present invention, the polyol used in [ example ] of patent document 4 is only a 3-functional polyether polyol (specifically, glycerol PO · EO adduct) (table 3). In the first example of patent document 4, the removability of the adhesive layer was not evaluated, but the present inventors found that the removability of the adhesive layer after storage in a high-temperature and high-humidity environment was more excellent in the adhesive of the present invention than in the adhesive described in patent document 4 (see the first example of [ example ] and comparative example 2).

The other polyether polyol to be used as the raw material polyol (x) if necessary is a 2-functional polyether polyol (x3) having no EO group, a 3-functional polyether polyol (x4) having no EO group, or a polyether polyol having 4 or more functions.

The raw material polyol (x) may contain one or more polyester polyols along with a plurality of polyether polyols including one or more 2-functional polyether polyols (x1) and one or more 3-functional polyether polyols (x2) within a range not to impair the effects of the present invention.

As the polyester polyol, known ones can be used. Examples of the polyester polyol include compounds (esterified products) obtained by esterification of one or more polyol components and one or more acid components.

As the polyol component of the raw material, there can be mentioned: 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, glycerol, trimethylolpropane, pentaerythritol, hexanetriol, and the like.

As the acid component of the raw material, there can be mentioned: succinic acid, methylsuccinic 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, 1, 4-naphthalenedicarboxylic acid, 4' -biphenyldicarboxylic acid, anhydrides of these acids, and the like.

In addition to the above, examples of the polyester polyol include compounds (ring-opened polymers) obtained by ring-opening polymerization of at least one lactone, such as polycaprolactone, poly (β -methyl- γ -valerolactone), and polypentanolactone.

The number average molecular weight (Mn) of the polyester polyol is not particularly limited, but 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. When the molecular weight is too small, the reactivity is high, and gelation may occur. When the molecular weight is too large, the reactivity is low, and the cohesive force of the polyurethane polyol (A) itself is insufficient.

< polyisocyanate (y) >

As the polyisocyanate compound (y), known ones can be used, and there can be mentioned: aromatic polyisocyanate, aliphatic polyisocyanate, aromatic aliphatic polyisocyanate, and alicyclic polyisocyanate.

Examples of the aromatic polyisocyanate include: 1, 3-phenylene diisocyanate, 4' -diphenyl diisocyanate, 1, 4-phenylene diisocyanate, 4' -diphenylmethane diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 4' -toluidine diisocyanate, 2,4, 6-triisocyanate toluene, 1,3, 5-triisocyanate benzene, dianisidine diisocyanate, 4' -diphenyl 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-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4, 4-trimethylhexamethylene diisocyanate, and the like.

Examples of the aromatic aliphatic polyisocyanate include: omega, omega '-diisocyanate-1, 3-dimethylbenzene, omega' -diisocyanate-1, 4-diethylbenzene, 1, 4-tetramethylxylene diisocyanate, 1, 3-tetramethylxylene diisocyanate, and the like.

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-2, 6-cyclohexane diisocyanate, 4' -methylenebis (cyclohexyl isocyanate), 1, 4-bis (isocyanatomethyl) cyclohexane, and the like.

In addition, as the polyisocyanate, there may be mentioned: trimethylolpropane adduct, biuret (biuret) isomer, and trimer (the trimer including an isocyanurate ring) of the polyisocyanate.

The polyisocyanate (y) is preferably 4,4' -diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanatomethyl-3, 5, 5-trimethylhydroxyethyl isocyanate (isophorone diisocyanate), or the like.

< catalyst >

As the catalyst, known one can be used, and examples thereof include tertiary amine compounds, organometallic compounds and the like.

Examples of the tertiary amine compound include triethylamine, triethylenediamine, and 1,8-Diazabicyclo (5,4,0) -undecene-7 (1,8-Diazabicyclo (5.4.0) -undecene-7, DBU).

Examples of the organometallic compound include tin compounds and non-tin compounds.

Examples of the tin compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate (dibutyltin dimaleate), dibutyltin dilaurate (DBTD L), dibutyltin diacetate, dibutyltin sulfide, tributyltin oxide, tributyltin acetate, triethylethoxytin (tributylethoxytin), tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

Examples of the non-tin compound include: titanium systems such as dibutyltitanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride; lead-based materials such as lead oleate, lead 2-ethylhexoate, lead benzoate, and lead naphthenate; iron series such as iron 2-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-based compounds such as zirconium naphthenate.

One or more kinds of the catalyst may be used.

When the reactivity of each of the plural kinds of polyols (x) used in combination is different, there is a problem that gelation or clouding of the reaction solution is likely to occur in a single catalyst system due to the difference in reactivity. In this case, by using two catalysts, the reaction (for example, reaction rate) can be easily controlled, and the problem can be solved. That is, in the present invention, it is preferable to use two kinds of catalysts. The combination of the two catalysts is not particularly limited, and tertiary amine/organic metal system, tin system/non-tin system, tin system/tin system, and the like can be cited. Tin-based/tin-based is preferred, and dibutyltin dilaurate and tin 2-ethylhexanoate are more preferred.

The mass ratio of tin 2-ethylhexanoate to dibutyltin dilaurate (tin 2-ethylhexanoate/dibutyltin dilaurate) is not particularly limited, but is preferably greater than 0 and less than 1, and more preferably 0.2 to 0.6. When the mass ratio is 1 or more, the balance of the catalytic activity is poor, and there is a problem that gelation is likely to occur.

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

< solvent >

If necessary, one or more solvents may be used for the polymerization of the polyurethane polyol (A). As the solvent, known ones can be used, and there can be mentioned: methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, and the like. In terms of solubility of the polyurethane polyol (a), boiling point of the solvent, and the like, ethyl acetate, toluene, and the like are particularly preferable.

< polymerization Process >

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 used.

The polymerization order is not particularly limited, and there may be mentioned:

sequence 1) a sequence in which a plurality of polyols (x), one or more polyisocyanates (y), optionally one or more catalysts, and optionally one or more solvents are added together to a flask;

sequence 2) A plurality of polyols (x), optionally one or more catalysts, and optionally one or more solvents were added to a flask, and one or more polyisocyanates (y) were added dropwise thereto.

The sequence 2) is preferred from the viewpoint of easy control of the reaction.

The reaction temperature in the case of using a catalyst is preferably less than 100 ℃ and more preferably from 85 ℃ to 95 ℃. When the reaction temperature is 100 ℃ or higher, there is a problem that the reaction rate, the crosslinked structure, and the like are difficult to control, and it is difficult to produce the polyurethane polyol (a) having a desired molecular weight.

The reaction temperature in the case where no catalyst is used is preferably 100 ℃ or higher, more preferably 110 ℃ or higher. The reaction time in the case where no catalyst is used is preferably 3 hours or more.

The weight average molecular weight (Mw) of the polyurethane polyol (a) is preferably 1 to 50 ten thousand, more preferably 3 to 40 ten thousand, and particularly preferably 5 to 35 ten thousand. When the Mw of the polyurethane polyol (a) is in an appropriate range, good coatability can be easily obtained.

(polyfunctional isocyanate Compound (B))

As the polyfunctional isocyanate compound (B), known ones can be used, and the compounds exemplified for the polyisocyanate (y) which is a raw material of the polyurethane polyol (a) (specifically, aromatic polyisocyanate, aliphatic polyisocyanate, aromatic aliphatic polyisocyanate, alicyclic polyisocyanate, and trimethylolpropane adduct/biuret product/trimer thereof) can be used.

(plasticizer (P))

The adhesive of the present invention may further comprise one or more plasticizers (P) in terms of improving wettability. The plasticizer (P) is not particularly limited, and is preferably a fatty acid ester having 10 to 30 carbon atoms or the like from the viewpoint of compatibility with other components.

Examples of the fatty acid ester having 10 to 30 carbon atoms include: esters of C6-C18 monobasic or polybasic acids and C18 or less branched alcohols; esters of C14-C18 unsaturated fatty acids or branched acids and alcohols having a valence of 4 or less; and esters of C6-C18 monobasic or polybasic acids and polyalkylene glycols.

Examples of the ester of a C6-18 monobasic or polybasic acid and a C18 or less branched alcohol include: isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isostearyl palmitate, isocetyl stearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trioleylene trimellitate, and triisocetyl trimellitate.

Examples of the unsaturated fatty acid or branched acid having 14 to 18 carbon atoms include: myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, isostearic acid, and the like. Examples of the alcohols having a valence of 4 or less include: ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitan, and the like.

The ester of a C6-18 monobasic or polybasic acid with a polyalkylene glycol includes: polyethylene glycol dihexanoate, polyethylene glycol di-2-ethylhexanoate, polyethylene glycol dilaurate, polyethylene glycol dioleate, and diethylene glycol methyl ether adipate.

Among them, the plasticizer (P) is preferably one having one or more EO groups in one molecule, since the above effect (the effect of improving the removability and the coatability of the adhesive layer when placed in a high-temperature and high-humidity environment) is effectively exhibited. 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, but is preferably 300 to 1000, more preferably 400 to 900, and particularly preferably 500 to 850, from the viewpoint of enhancing the wetting rate and the like.

(solvent)

The adhesives of the invention may optionally contain more than one solvent. As the solvent, known ones can be used, and there can be mentioned: methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, and the like. In view of solubility of the polyurethane polyol (a), boiling point of the solvent, and the like, ethyl acetate, toluene, and the like are particularly preferable.

(other optional ingredients)

The adhesive of the present invention may contain one or more other optional components as necessary within a range not impairing the effects of the present invention. As other optional components, there may be mentioned: a catalyst, a resin other than a 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 leveling agent, an anticorrosive agent, a heat stabilizer, a polymerization inhibitor, an antifoaming agent, a lubricant, and the like.

Examples of the filler 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 decomposers such as sulfur-based antioxidants and phosphorus-based antioxidants.

Examples of the phenolic antioxidant include:

monophenol antioxidants such as 2, 6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2, 6-di-tert-butyl-4-ethylphenol, and stearyl β - (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate;

bisphenol antioxidants such as 2,2 '-methylenebis (4-methyl-6-tert-butylphenol), 2' -methylenebis (4-ethyl-6-tert-butylphenol), 4 '-thiobis (3-methyl-6-tert-butylphenol), 4' -butylidenebis (3-methyl-6-tert-butylphenol), and 3, 9-bis [1, 1-dimethyl-2- [ β - (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy ] ethyl ]2,4,8, 10-tetraoxaspiro [5,5] undecane;

1,1, 3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [ methylene-3- (3',5' -di-t-butyl-4 ' -hydroxyphenyl) propionate ] methane, ethylene glycol bis [3,3' -bis- (4' -hydroxy-3 ' -t-butylphenyl) butyrate ], and 1,3, 5-tris (3',5' -di-t-butyl-4 ' -hydroxybenzyl) -S-triazine-2, 4,6- (1H,3H,5H) trione, And polymeric phenol antioxidants such as tocopherol.

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

Examples of the phosphorus-based antioxidant include: triphenyl phosphite, diphenylisodecyl phosphite, and phenyldiisodecyl phosphite, and the like.

Examples of the ultraviolet absorber include: benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, oxalic acid aniline-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, triazine-based ultraviolet absorbers, and the like.

Examples of benzophenone-based ultraviolet absorbers include: 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2' -dihydroxy-4-dimethoxybenzophenone, 2' -dihydroxy-4, 4' -dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane and the like.

Examples of the benzotriazole-based ultraviolet absorber include: 2- (2' -hydroxy-5 ' -methylphenyl) benzotriazole, 2- (2' -hydroxy-5 ' -tert-butylphenyl) benzotriazole, 2- (2' -hydroxy-3 ',5' -di-tert-butylphenyl) benzotriazole, 2- (2' -hydroxy-3 ' -tert-butyl-5 ' -methylphenyl) -5-chlorobenzotriazole, 2- (2' -hydroxy-3 ',5' -di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2' -hydroxy-3 ',5' -di-tert-amylphenyl) benzotriazole, 2- (2' -hydroxy-4 ' -octyloxyphenyl) benzotriazole, 2- (2' -hydroxy-5 ' -t-butylphenyl) benzotriazole, 2- (2' -hydroxy-3 ',5' -di-tert-amylphenyl) benzotriazole, and mixtures thereof, 2- [2 '-hydroxy-3' - (3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5 '-methylphenyl ] benzotriazole, 2' -methylenebis [4- (1,1,3, 3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol ], 2(2 '-hydroxy-5' -methacryloxyphenyl) -2H-benzotriazole, and the like.

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

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

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

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

Examples of the ultraviolet stabilizer include: nickel bis (octylphenyl) sulfide, [2,2' -thiobis (4-tert-octylphenolate) ] -nickel n-butylamine, nickel complex-3, 5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid monoethyl ester, quencher for benzoate, and nickel dibutyldithiocarbamate, and the like.

As the leveling agent, there can be mentioned: acrylic leveling agents, fluorine leveling agents, and silicon leveling agents. As the acrylic leveling agent, there may be mentioned: pelleyfarol (Polyflow) No.36, Polyflow No.56, Polyflow No.85HF, Polyflow No.99C (all manufactured by Kyoeisha chemical Co., Ltd.), and the like. Examples of the fluorine-based leveling agent include: meijia Fa (Megafac) F470N, Megafac F556 (both manufactured by Diegon (DIC)). Examples of the silicon leveling agent include grand dick (Grandic) PC4100 (manufactured by dean-son (DIC)).

(blending ratio)

The 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 required. The blending ratio of these is not particularly limited, and preferred blending ratios are as follows.

The amount of the one or more polyfunctional isocyanates (B) is preferably 1 to 20 parts by mass, more preferably 5 to 15 parts by mass, relative to 100 parts by mass of the one or more polyurethane polyols (a). When the amount of the one or more polyfunctional isocyanates (B) is too small, the cohesive force of the adhesive is insufficient, and when it is too large, the adhesive force is insufficient.

The amount of the one or more plasticizers (P) is preferably 10 to 70 parts by mass, more preferably 20 to 50 parts by mass, relative to 100 parts by mass of the one or more polyurethane polyols (a). If the amount of the one or more plasticizers (P) is too small, the effect of adding the plasticizer (P) (wettability-improving effect) is not effectively exhibited, and if it is too large, the effect of adding the plasticizer (P) cannot be expected to be improved in accordance with the amount of the plasticizer (P) added, and the amount of the urethane polyol (a) which is a main active ingredient of the adhesive which is essentially required is relatively small.

[ adhesive sheet ]

The adhesive sheet of the present invention comprises a substrate sheet and an adhesive layer containing a cured product of the adhesive of the present invention. The adhesive layer may be formed on one side or both sides of the substrate sheet. If necessary, the exposed surface of the adhesive layer may be covered with a release sheet. Further, the release sheet is peeled off when the adhesive sheet is attached to the adherend.

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

Fig. 2 is a schematic cross-sectional view of an adhesive sheet according to embodiment 2 of the present invention. In fig. 2, reference numeral 20 denotes an adhesive sheet, reference numeral 21 denotes a base sheet,

reference numerals

22A and 22B denote adhesive layers, and

reference numerals

23A and 23B denote release sheets.

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

The resin constituting the resin sheet is not particularly limited, and includes: ester resins such as polyethylene terephthalate (PET); olefin resins such as Polyethylene (PE) and polypropylene (PP); vinyl resins such as polyvinyl chloride; amide resins such as nylon 66; urethane resin (including foam); combinations of these, and the like.

The thickness of the resin sheet other than the polyurethane (polyurethane) sheet is not particularly limited, and is preferably 15 to 300 μm. The thickness of the polyurethane sheet (including the foam) is not particularly limited, and is preferably 20 μm to 50,000 μm.

The paper is not particularly limited, and may be plain paper, coated paper, and coated paper.

The constituent metal of the metal foil is not particularly limited, and aluminum, copper, a combination thereof, and the like can be mentioned.

The release sheet is not particularly limited, and a known release sheet obtained by applying a known release treatment such as coating with a release agent to the surface of a resin sheet, paper, or the like can be used.

The adhesive sheet can be produced by a known method.

First, the adhesive of the present invention is applied to the surface of a substrate sheet to form a coating layer containing the adhesive of the present invention. As the coating method, a known method can be used, and examples thereof include a roll coater (roll coater) method, a comma coater (comma coater) method, a die coater (die coater) method, a reverse coater (reverse coater) method, a silk screen printing (silk screen) method, and a gravure coater (gravure coater) method.

Next, the coating layer is dried and cured to form an adhesive layer containing a cured product of the adhesive of the present invention. The heating and drying temperature is not particularly limited, but is preferably about 60 ℃ to 150 ℃. The thickness of the adhesive layer (thickness after drying) varies depending on the application, but is preferably 0.1 to 200 μm.

Next, a release sheet is attached to the exposed surface of the adhesive layer by a known method as needed.

Thus, a single-sided adhesive sheet can be produced.

By performing the above operation on both sides, a double-sided adhesive sheet can be manufactured.

In contrast to the above method, the adhesive of the present invention may be applied to the surface of a release sheet to form a coating layer containing the adhesive of the present invention, the coating layer may be dried and cured to form an adhesive layer containing a cured product of the adhesive of the present invention, and finally, a substrate sheet may be laminated on the exposed surface of the adhesive layer.

(use)

The adhesive sheet of the present invention can be used in the form of a tape, a label, a sheet, a double-sided tape, or the like. The adhesive sheet of the present invention can be suitably used as a surface protective sheet, a cosmetic sheet, an anti-slip sheet, and the like.

Flat panel displays such as liquid crystal displays (L CD) and organic electroluminescence displays (E L D), and touch panel displays in which the flat panel displays and touch panels are combined are widely used in electronic devices such as Televisions (TVs), Personal Computers (PCs), mobile phones, and portable information terminals.

The adhesive sheet of the present invention is suitably used as a surface protective sheet for flat panel displays, touch panel displays, substrates and optical members produced or used in the production process thereof.

The adhesive sheet of the present invention has good adhesiveness and good removability even when placed in a more severe high-temperature and high-humidity environment than before, and is therefore preferred.

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

Examples

Synthetic examples, examples of the present invention, and comparative examples are described below. In the following description, "part" means "part by mass" and "%" means "% by 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 a Gel Permeation Chromatography (GPC) method. The measurement conditions were as follows. Furthermore, Mw and Mn are both polystyrene equivalent values.

< measurement Condition >

The device comprises the following steps: shimadzu excellence (Shimadzu project) (manufactured by Shimadzu corporation),

A column including 3 Soidex L F-804 (Showa Denko K.K.) connected in series,

A detector: a differential refractive index detector,

Solvent: tetrahydrofuran (THF),

The flow rate is 0.5m L/min,

Temperature of the solvent: at 40 deg.C,

Sample concentration: 0.1 percent,

The amount of sample injected was 100. mu. L.

[ Material ]

The materials used are as follows.

< 2-functional polyether polyol (x1) having EO group >

(x 1-1): triethylene glycol, Mn150, a hydroxyl number of 2 ("triethylene glycol" manufactured by Mitsubishi chemical corporation),

(x 1-2): polyethylene glycol (PEG), Mn200, a hydroxyl number of 2 ("PEG-200" manufactured by Toho chemical industries Co., Ltd.)

(x 1-3): polyethylene glycol (PEG), Mn400, a hydroxyl number of 2 ("PEG-400" manufactured by Toho chemical industries Co., Ltd.)

(x 1-4): polyethylene glycol (PEG), Mn1000, a hydroxyl number of 2 ("PEG-1000" manufactured by Toho chemical industries Co., Ltd.)

(x 1-5): polyethylene glycol (PEG), Mn2000, a hydroxyl number of 2 ("PEG-2000" manufactured by Toho chemical industries Co., Ltd.)

(x 1-6): polyethylene glycol (PEG), Mn4000, hydroxyl number 2 ("PEG-4000" manufactured by Toho chemical industries Co., Ltd.)

(x 1-7): polyethylene glycol (PEG), Mn6000, hydroxyl number 2 ("PEG-6000" manufactured by Toho chemical industries Co., Ltd.)

(x 1-8): polyoxyethylene polyoxypropylene Block Polymer, Mn1200, hydroxyl number 2 ("Epan 450" manufactured by first Industrial pharmaceutical Co., Ltd.)

(x 1-9): EO adduct of Propylene Glycol (PG), Mn4000, and hydroxyl number 2 ("Excinol 510" manufactured by Asahi glass Co., Ltd.).

< 3-functional polyether polyol (x2) having EO group >

(x 2-1): glycerol PO. EO adduct (modified with ethylene glycol at the end of glycerol polypropylene glycol), Mn3000, hydroxyl number 3 ("AdDisco polyether (ADEKA polyether) AM-302" manufactured by AdDisco (ADEKA)),

(x 2-2): glycerol PO. EO adduct (modified with ethylene glycol at the end of glycerol polypropylene glycol), Mn5000, and hydroxyl number 3 ("ADEKA polyester AM-502" manufactured by Adeka corporation).

< 2-functional polyether polyol (x3) having no EO group >

(x 3-1): polyoxypropylene glycol, Mn4000, and a hydroxyl number of 2 ("Sannesis PP-4000" manufactured by Sanyo chemical industries, Inc.).

< 3-functional polyether polyol (x4) having no EO group >

(x 4-1): polyoxypropylene Glycerol ether, Mn1500, and hydroxyl number 3 ("SannixGP-1500" manufactured by Sanyo chemical industries, Ltd.).

< 2-functional polyester polyol (x5) >, having no EO group

(x 5-1): an adipic acid/3-methyl-1, 5-pentanediol condensate, Mn1000, and a hydroxyl number of 2 ("Korea Polyol (Kuraray Polyol) P-1010") manufactured by Korea (Kuraray).

< polyisocyanate (y) >

(y-1): 1, 6-hexamethylene diisocyanate ("Desmodur H" manufactured by Tosoh corporation),

(y-2): 1, 3-xylene diisocyanate ("Takenate 500" manufactured by Mitsui chemical Co., Ltd.).

< polyfunctional isocyanate Compound (B) >

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

(B-2) hexamethylene diisocyanate/trimethylolpropane adduct ("crotonate) H L" 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 number: on average 6 ("Adekacizer RS 700") manufactured by Adekacizer (ADEKA) Inc.),

(P-2): polyether ester compound (polyethylene glycol (Mw600) di-2-ethylhexanoate), EO number: on average 12.8 ("Adekacizer RS 735" manufactured by Adekaica corporation),

(P-3): polyethylene glycol fatty acid ester (PEG-8 dioleate), EO number: on average 8 ("pergol 24-O" manufactured by Toho chemical industries Inc.),

(P-4): isopropyl myristate, EO group-free ("Nikol (NIKKO L) IPM-100") manufactured by Nikko Chemicals, Inc.

[ Synthesis examples of polyurethane polyol ]

(Synthesis example 1)

1 part of a 2-functional polyether polyol having an EO group (x1-1) and 99 parts of a 3-functional polyether polyol having an EO group (x2-1) were charged in a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a thermometer, and a dropping funnel. To the additive solution were added 170 parts of toluene, 0.03 parts of dibutyltin dilaurate as a catalyst, and 0.01 parts of tin 2-ethylhexanoate. After gradually raising the temperature to 90 ℃ under a nitrogen atmosphere, an amount (5.7 parts) of polyisocyanate (y-1) such that the NCO/OH ratio (functional group ratio) became 0.6 was added dropwise into the flask. After the 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) spectroscopy, the reaction solution was cooled to terminate the reaction.

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

The kinds of the raw material polyol and the raw material polyisocyanate used, the blending ratio of these, and the Mw of the obtained polyurethane polyol (A-1) are shown in Table 1-1.

In tables 1-1 to 1-3, the unit of the amount of polyol (x1) to polyol (x5) is [ parts ]. The amount of polyisocyanate (y) to be blended is expressed in terms of NCO/OH ratio (functional group ratio).

The amount of the polyisocyanate (y-1) was calculated as follows.

(amount of (y-1) ([ part ] ═ part)

(NCO/OH ratio) × ((molecular weight of y-1)/((number of NCO groups of y-1))/(×

[ ((x1-1) parts)/((x 1-1) molecular weight) × ((x1-1) hydroxyl number)

+ ((X2-1) parts)/((X2-1) molecular weight) × ((X2-1) hydroxyl number)

＝0.6×168/2×(1/150×2+99/3000×3)

≒5.7

(Synthesis examples 2 to 21)

In Synthesis examples 2 to 21, polyurethane polyols (A-2) to (A-19) and (D-1) to (D-2) were obtained in the same manner as in Synthesis example 1 except that the types of the raw material polyol and the raw material polyisocyanate used and the blending ratio thereof were changed as shown in tables 1-1 to 1-3. The Mw of the polyurethane polyol obtained in each synthesis example 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 by means of a disperser to obtain polyol mixture (D-3).

The kind of the raw material polyol used, the blending ratio of these, and Mw of the obtained polyol mixture (D-3) are shown in tables 1 to 3.

(example 1)

A urethane adhesive was obtained by blending 100 parts of the polyurethane polyol (A-1) obtained in Synthesis example 1, 30 parts of a plasticizer (P-1), 0.5 parts of an antioxidant ("Irganox L135" manufactured by BASF corporation), 8 parts of a polyfunctional isocyanate compound (B-1), and 100 parts of ethyl acetate as a solvent, and stirring the mixture with a disperser.

The kinds and blending ratios of the materials used are shown in Table 2-1.

A polyethylene terephthalate (PET) sheet ("lolo miller (L umirror) T-60" manufactured by dongli corporation, thickness 50 μm) was prepared as a substrate sheet, the obtained urethane adhesive was applied to one surface of the substrate sheet at an application speed of 3m/min using a comma coater (registered trademark) so that the thickness after drying became 12 μm, and thereafter, the coatability was evaluated.

The resultant coating layer was dried at 100 ℃ for 2 minutes to form an adhesive layer, a release sheet (Super Stik SP-PET38 manufactured by Linaceae (L intec)) having a thickness of 38 μm was attached to the adhesive layer to obtain an adhesive sheet, and the obtained adhesive sheet was cured at 23 to 50% RH for one week and then evaluated for adhesion and removability.

(example 2 to example 19, comparative example 1 to comparative example 2)

Urethane adhesives and adhesive sheets were obtained in the same manner as in example 1, except that the types and blending ratios of the materials used in examples 2 to 19 and comparative examples 1 to 2 were changed as shown in tables 2-1 to 2-3.

In the same manner as in example 1, the evaluation of coatability was performed when forming a coating layer.

The obtained adhesive sheet was cured for one week under 23 to 50% RH in the same manner as in example 1, and then the adhesive force and removability were evaluated.

Comparative example 3

100 parts of the polyol mixture (D-3) obtained in Synthesis example 22, 44 parts of the polyfunctional isocyanate compound (B-3), 0.04 parts of Nacem Ferric Iron (manufactured by Nippon chemical industries, Ltd.) as a catalyst, and 266 parts of ethyl acetate as a diluent solvent were blended, and stirred by a disperser to obtain a urethane adhesive. The amount of each material other than the solvent used is expressed in terms of nonvolatile content. The kinds and blending ratios of the materials used are shown in tables 2 to 3.

An adhesive sheet was obtained in the same manner as in example 1, except that the obtained adhesive was used and the drying temperature of the coating layer was set to 130 ℃.

The adhesive sheet obtained was cured for one week under 23 to 50% RH conditions in the same manner as in example 1, and then evaluated for adhesion and removability.

[ evaluation items and evaluation methods ]

The evaluation items and evaluation methods of the adhesive and the adhesive sheet are as follows.

(coatability)

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

< decision reference >

○ good, the coated surface was smooth.

△ (clear lines), coating unevenness was observed on the coated surface to such an extent that it was practically not impaired.

× (not required) rolling lines or skew were observed on the coated side.

(adhesive force)

Two test pieces having a width of 25mm and a length of 100mm were cut out from the adhesive sheet. The two test pieces were peeled off from each other in an atmosphere of 23 to 50% RH, and a soda glass plate was stuck to the exposed surface of the adhesive layer and pressed with a 2kg roller.

One of the two laminates obtained was left to stand in an atmosphere of 23 to 50% RH for 24 hours (temperature and humidity condition 1).

The other laminate was placed in an oven at 85 to 85% RH for 72 hours (temperature and humidity condition 2), taken out from the oven, and air-cooled in an environment at 23 to 50% RH for 1 hour.

Regarding each laminate, the adhesive force was measured under the conditions of a peel speed of 300mm/min and a peel angle of 180 ° using a tensile tester in accordance with Japanese Industrial Standards (JIS) Z0237, and evaluated based on the following criteria.

< decision reference >

○ (good): less than 20mN/25 mm.

△ (optional) is 20mN/25mm to 100mN/25 mm.

× (not) is greater than 100mN/25 mm.

(removability)

3 test pieces having a width of 70mm and a length of 100mm were cut out from the adhesive sheet. For 3 test pieces, the release sheet was peeled off in an environment of 23 to 50% RH, and a soda glass plate was attached to the surface of the exposed adhesive layer, followed by pressing with a laminator.

The obtained 3 laminates were placed in an oven set at 40 to 90% RH (temperature and humidity condition 1), 60 to 90% RH (temperature and humidity condition 2), and 85 to 85% RH (temperature and humidity condition 3), respectively, for 72 hours.

After 3 laminates were taken out from the oven and air-cooled in an environment of 23 to 50% RH for 1 hour, the adhesive sheet was peeled from the glass plate, and removability was evaluated, and the surface of the glass plate on the side to which the adhesive sheet was attached was irradiated with a light of a light Emitting Diode (L light Emitting Diode, L ED) in a dark room and evaluated by visual observation under the following criteria.

< decision reference >

○ (good), no adhesive layer component was observed on the glass surface.

△ (optional) thin adhesive layer components were observed to adhere at 1-2 points on the glass surface.

× (not required) the adhesion of thin adhesive layer components was observed at 3 or more points on the glass surface, or the adhesion of thick adhesive layer components was observed at 1 to 2 points on the glass surface.

[ evaluation results ]

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

In examples 1 to 19, a urethane adhesive was produced, which contained:

a polyurethane polyol (a) which is a copolymerization reaction product of a plurality of polyols (x) comprising one or more 2-functional polyether polyols (x1) having EO groups and one or more 3-functional polyether polyols (x2) having EO groups, and one or more polyisocyanates (y); and

a polyfunctional isocyanate compound (B).

The urethane adhesives obtained in examples 1 to 19 all had good or relatively good coatability.

The adhesive sheets obtained in examples 1 to 19 had good or relatively good adhesive force under any of the test conditions of 23 to 50% RH (temperature and humidity condition 1) and 85 to 85% RH (temperature and humidity condition 2).

The pressure-sensitive adhesive sheets obtained in examples 1 to 19 were good or relatively good in removability under any of test conditions of 40 to 90% RH (temperature and humidity condition 1), 60 to 90% RH (temperature and humidity condition 2), and 85 to 85% RH (temperature and humidity condition 3).

In particular, the results of examples 2 to 5, 10 to 14, and 18, which produced urethane adhesives in which,

the amount of the one or more 2-functional polyether polyols (x1) is 1 to 30 parts by mass and the amount of the one or more 3-functional polyether polyols (x2) is 99 to 70 parts by mass, when the total amount of the one or more 2-functional polyether polyols (x1) and the one or more 3-functional polyether polyols (x2) is set to 100 parts by mass,

the 2-functional polyether polyol (x1) has an Mn of 200 to 4,000,

the 2-functional polyether polyol (x1) comprises PEG.

Further, the adhesive sheets obtained in examples 1 to 18 using the plasticizer (P) having an EO group gave better results than those obtained in example 19 not using the plasticizer (P).

The adhesive sheet obtained in comparative example 1, which used only the 3-functional polyether polyol (x4) having no EO group and the 2-functional polyester polyol (x5) having no EO group as the raw material polyol of the polyurethane polyol, was poor in removability under the test conditions of 85 to 85% RH (temperature and humidity condition 3).

The adhesive sheet obtained in comparative example 2, which used only 3-functional polyether polyol (x2) having an EO group as the raw material polyol of polyurethane polyol, was poor in removability under the test conditions of 85 to 85% RH (temperature and humidity condition 3).

The adhesive obtained in comparative example 3, in which a mixture of a 2-functional polyether polyol (x3) having no EO group and a 3-functional polyether polyol (x4) having no EO group was used instead of the polyurethane polyol, was poor in coatability.

The adhesive sheet obtained in comparative example 3 had poor adhesive force under any of the test conditions of 23 to 50% RH (temperature and humidity condition 1) and 85 to 85% RH (temperature and humidity condition 2).

Since the adhesive sheet obtained in comparative example 3 did not use the plasticizer (P), the removability was good or relatively good under the test conditions of 85 to 85% RH (temperature and humidity condition 3).

[ tables 1-1]

[ tables 1-2]

[ tables 1 to 3]

[ Table 2-1]

[ tables 2-2]

[ tables 2 to 3]

	Comparative example 1	Comparative example 2	Comparative example 3
				A-1
A-2
				A-3
A-4
				A-5
A-6
				A-7
A-8
				A-9
A-10
				A-11
A-12
				A-13
A-14
				A-15
A-16
				A-17
A-18
				A-19
D-1	100
				D-2		100
D-3			100
				IRGANOX 1135	1	1	1
B-1	8	8
				B-2
B-3			44
				P-1
P-2		45
				P-3
P-4	30
				Coating property	Δ	Δ	×
Adhesive force (23 ℃ -50% RH)	○	○	×
				Adhesive force (85-85% RH)	○	○	×
Repeelability (40 ℃ -90% RH)	○	○	○
				Repeelability (60 ℃ -90% RH)	Δ	Δ	○
Repeelability (85 ℃ -85% RH)	×	×	Δ

The present invention is not limited to the above-described embodiments and examples, and can be appropriately modified in design without departing from the spirit of the present invention.

Claims

1. An adhesive, comprising:

a polyurethane polyol (a) which is a copolymerization reaction product of a plurality of polyols (x) comprising one or more 2-functional polyether polyols (x1) having one or more ethyleneoxy groups in one molecule and one or more 3-functional polyether polyols (x2) having one or more ethyleneoxy groups in one molecule, and one or more polyisocyanates (y); and

a polyfunctional isocyanate compound (B),

the amount of the polyfunctional isocyanate compound (B) is 1 to 20 parts by mass per 100 parts by mass of the polyurethane polyol (A).

2. The adhesive of claim 1, further comprising a plasticizer (P).

3. The adhesive according to claim 2, wherein the plasticizer (P) has one or more vinyloxy groups in one molecule.

4. The adhesive according to any one of claims 1 to 3, wherein the 2-functional polyether polyol (x1) has a number average molecular weight of 200 to 4,000.

5. The adhesive of any one of claims 1 to 3, wherein the one or more 2-functional polyether polyols (x1) comprise polyethylene glycol.

6. An adhesive sheet comprising a substrate sheet, and an adhesive layer containing a cured product of the adhesive according to any one of claims 1 to 5.