CN109306257B

CN109306257B - Urethane adhesive, adhesive sheet, and display

Info

Publication number: CN109306257B
Application number: CN201811023688.XA
Authority: CN
Inventors: 田邉慎吾; 斋藤秀平
Original assignee: Toyo Ink SC Holdings Co Ltd; Toyochem Co Ltd
Current assignee: Toyochem Co Ltd; Artience Co Ltd
Priority date: 2015-09-17
Filing date: 2016-09-13
Publication date: 2021-06-15
Anticipated expiration: 2036-09-13
Also published as: TWI601797B; CN107109178A; KR101813846B1; WO2017047077A1; JP6090525B1; TW201718810A; CN107109178B; JP2017057383A; CN109306257A; KR20170081271A

Abstract

The invention provides a urethane adhesive, an adhesive sheet, and a display. The urethane adhesive provided by the invention can be applied in a thick film and can form an adhesive layer with good wet-heat whitening resistance. The urethane adhesive of the present invention comprises a urethane prepolymer (a) which is a reaction product of one or more polyols (a-1) other than polyether polyols having one or more EO groups in one molecule, one or more polyether polyols (a-2) having one or more EO groups in one molecule, and one or more polyisocyanates (b). In one embodiment, the urethane adhesive of the present invention may include a urethane prepolymer (a) and a β -diketone compound (X).

Description

Urethane adhesive, adhesive sheet, and display

Divisional patent application

The present patent application is a divisional application of an invention patent application entitled "urethane adhesive, method for producing the same, adhesive sheet, and display" filed under application No. 201680004639.4, and the filing date of the present patent application is 2016, 09, month 13.

Technical Field

The invention relates to a urethane adhesive, an adhesive sheet, and a display.

Background

Flat panel displays (LCD) such as Liquid Crystal Displays (LCD) and organic electroluminescent displays (OELD), and touch panel displays (touch panel displays) formed by combining the flat panel displays and touch panels are widely used in electronic devices such as Televisions (TVs), Personal Computers (PCs), mobile phones, and portable information terminals.

In recent years, the various displays are being made thin and lightweight. Among these, thin and lightweight OELDs are expected to be attracting attention because they can obtain high brightness with low power. The OELD has a laminated structure in which one or more organic layers such as an organic light-emitting layer and an organic charge transport layer are laminated on a substrate. OELDs can also be made flexible by using a plastic film as the substrate.

In general, an organic Electroluminescence (EL) element tends to have a decreased property such as emission luminance, emission efficiency, and emission uniformity after a long time use. The organic EL element is thin as a whole, and is considered to have deteriorated characteristics due to oxidation of an electrode and modification of an organic substance by oxygen, moisture, or the like, and oxidative decomposition of an organic material by heat generation during driving. Further, interface separation may occur between the components due to interface stress or the like generated between the components due to a difference in thermal expansion coefficient between the components. In order to solve such problems, improvement of a sealant, a barrier layer, and the like has been studied. For example, the formation of a sealant, a barrier layer, and the like using a coating film is being studied.

Cracks, damages, and the like are generated in a sealant, a barrier layer, and the like including a coating film due to impact, vibration, and the like generated in a manufacturing process, and these may cause deterioration of an organic EL element. Therefore, it is preferable that the thin film or the fragile member be protected from impact, vibration, or the like. Conventionally, as a surface protection sheet for protecting various optical members from scratches, dust adhesion, and the like, an adhesive sheet having an adhesive layer formed on a base sheet has been widely used, but performance for protecting various optical members from impact, vibration, and the like has not been studied.

In the present specification, the "adhesive sheet" is an adhesive sheet having removability (removable adhesive sheet).

Patent document 1 discloses an acrylic adhesive containing an acrylic derivative, an acrylic derivative polymer, and a high molecular weight crosslinking agent (claim 1).

As a means for improving impact resistance, in addition to the composition of the adhesive, thickening of the adhesive layer is also considered.

Patent document 2 discloses an acrylic adhesive containing a monofunctional urethane acrylate oligomer having a specific weight average molecular weight (Mw), an acrylate monomer, and a radical photoinitiator as an adhesive that can be applied as a thick film (claim 1).

Patent document 3 discloses a urethane adhesive that can be applied as a thick film adhesive and contains a modified polyisocyanate obtained by reacting a polyisocyanate having an NCO functional group with a polyether compound containing one or more terminal active hydrogen functional groups per molecule and an average of 6 or more Ethylene Oxide (EO) units, and a polyol containing a liquid polycarbonate diol (claim 1).

Patent document 4 discloses an adhesive sheet for temporarily fixing a fragile member, which includes an adhesive layer obtained by curing a urethane adhesive containing a polyol and a polyfunctional isocyanate compound by a so-called one-shot method (claim 1).

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2015-17278

[ patent document 2] Japanese patent laid-open No. 2012-144726

[ patent document 3] Japanese patent laid-open publication No. 2013-136731

[ patent document 4] Japanese patent laid-open No. 2014-172989

Disclosure of Invention

[ problems to be solved by the invention ]

Patent document 1 describes: since the acrylic adhesive contains a high molecular weight polymer at a high concentration, it is excellent in impact absorbability even in the form of a thin film (paragraph 0027). In general, when the adhesive sheet is attached to an adherend such as an optical member, it is preferable that the adhesive layer satisfactorily wets and spreads without involving air in the interface with the adherend. This property is also referred to as "wettability". For example, the optical member may be inspected in a state where the adhesive sheet is attached. In this case, air trapped between the optical member and the adhesive sheet becomes an obstacle to inspection. In general, an acrylic adhesive is inferior in wettability to a urethane adhesive, and is not suitable for optical applications, etc., in which entrainment of air is prohibited.

Patent document 2 describes: the acrylic adhesive is less cured and shrunk during photopolymerization, so that the thickness can be made uniform, and an adhesive sheet having a good surface appearance can be obtained (paragraph 0012). However, the acrylic adhesive has the same problem as described above. In addition, the acrylic adhesive described in patent document 2 gradually decreases the amount of light such as ultraviolet light reaching from the surface of the coating layer to the inside thereof when the coating layer is photo-cured, and thus, in particular, in the coating layer having a thick film, curing unevenness in the thickness direction is likely to occur. Further, the suppression of curing shrinkage is not necessarily sufficient. Therefore, thick film coating is not easy.

The urethane adhesive described in patent document 3 has a high adhesive force and is not suitable for use in a removable application.

Patent document 4 does not mention any performance for protecting an adherend such as an optical member from impact, vibration, and the like, but a single method generally tends to deteriorate the surface smoothness of an adhesive layer due to curing shrinkage, and is not suitable for making a thick film.

In addition, in general, when the adhesive layer is exposed to a high-temperature and high-humidity environment, the adhesive layer may be clouded (also referred to as whitening) by moisture in the external environment, and the appearance may be deteriorated. Therefore, the adhesive layer is preferably excellent in resistance to wet whitening and heat whitening.

In addition, although the adhesive sheet generally protects an adherend such as an optical member from dust adhesion, it is preferable that the adhesive sheet itself used for various displays and the like has antistatic properties and low dust adhesion.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a urethane adhesive which can be applied in a thick film and can form an adhesive layer having excellent resistance to wet-heat whitening, and an adhesive sheet using the same.

Another object of the present invention is to provide a urethane adhesive which can be applied as a thick film and can form an adhesive layer having excellent resistance to wet-heat whitening and low antistatic properties and dust adhesion, and an adhesive sheet using the same.

[ means for solving problems ]

The present inventors have made extensive studies to achieve the above object, and as a result, the present invention has been completed.

The urethane adhesive according to embodiment 1 of the present invention includes:

a urethane prepolymer (A) which is a reaction product of one or more polyols (a-1) other than polyether polyols having one or more Ethyleneoxy (EO) groups in one molecule, one or more polyether polyols (a-2) having one or more Ethyleneoxy (EO) groups in one molecule, and one or more polyisocyanates (b); and

a beta-diketone compound (X).

The urethane adhesive according to embodiment 2 of the present invention includes:

a fatty acid ester (B).

The urethane adhesive of embodiment 1 is preferably,

there can be used a urethane prepolymer (A) obtained by reacting one or more polyols (a-1) other than a polyether polyol having one or more Ethyleneoxy (EO) groups in one molecule, one or more polyether polyols (a-2) having one or more Ethyleneoxy (EO) groups in one molecule, and one or more polyisocyanates (b), and

a beta-diketone compound (X) is prepared by a method for preparing the beta-diketone compound (X).

The adhesive sheet of the present invention includes an adhesive layer containing a cured product of the adhesive of embodiment 1 or embodiment 2 of the present invention.

The display of the present invention includes an adhesive layer containing a cured product of the adhesive of embodiment 1 or embodiment 2 of the present invention.

In the present specification, "ethyleneoxy group" is represented by the chemical formula "-CH₂CH₂The group represented by O- "may be abbreviated as" EO group ". Similarly, ethylene oxide (ethylene oxide) which forms an EO group by a ring-opening reaction may be abbreviated as "EO".

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, various physical properties are measured by the method described in "example".

[ Effect of the invention ]

According to the present invention, a urethane adhesive which can be applied as a thick film and can form an adhesive layer having excellent resistance to wet-heat whitening, and an adhesive sheet using the same can be provided.

The adhesive of embodiment 1 of the present invention containing the urethane prepolymer (a) and the β -diketone compound (X) can be applied as a thick film and can form an adhesive layer having excellent resistance to wet-heat whitening, antistatic properties, and low dust adhesion.

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 symbols ]

10. 20: adhesive sheet

11. 21: substrate sheet

12. 22A, 22B: adhesive layer

13. 23A, 23B: release sheet

Detailed Description

Carbamate adhesive "

The urethane adhesive of the present invention contains one or more specific urethane prepolymers (a).

The urethane adhesive according to embodiment 1 of the present invention contains one or more specific urethane prepolymers (a) and one or more β -diketone compounds (X).

The urethane adhesive according to embodiment 2 of the present invention contains one or more specific urethane prepolymers (a) and one or more fatty acid esters (B).

(urethane prepolymer (A))

The urethane prepolymer (a) is a reaction product obtained by copolymerizing a plurality of polyols (a) with one or more polyisocyanates (b). The urethane prepolymer (a) is a copolymer containing a plurality of monomer units derived from a plurality of polyols (a) and one or more polyisocyanates (b).

In the present invention, the plurality of polyols (a) are a combination of one or more polyols (a-1) other than a polyether polyol having one or more Ethyleneoxy (EO) groups in one molecule and one or more polyether polyols (a-2) having one or more Ethyleneoxy (EO) groups in one molecule.

< polyol (a-1) >

The polyol (a-1) is an arbitrary polyol except for a polyether polyol having one or more EO groups in one molecule. Examples of the polyol (a-1) include polyacrylic polyol, polyester polyol, polyether polyol having no EO group, polycaprolactone polyol, polycarbonate polyol, and castor oil polyol. Among these, polyester polyols, polyether polyols having no EO group, polycaprolactone polyols, and polycarbonate polyols are preferable, and polyester polyols and polyether polyols having no EO group are more preferable.

Polyester polyols are polyols having a polyester structure. The polyol is a polycondensate of one or more acid components and one or more polyol components, and can be obtained by esterification of one or more acid components with one or more polyol components.

As the acid component of the raw material, there can be mentioned: polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, phthalic anhydride, isophthalic acid, and trimellitic acid.

As the polyol component of the raw material, there can be mentioned: 2-functional polyols having two hydroxyl groups (also referred to as diols or diols) such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, 1, 4-butanediol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 3' -dimethylolheptane, butylethylpentanediol, polyoxyethylene glycol, and polyoxypropylene glycol; and 3 or more functional polyols having three or more hydroxyl groups such as glycerin, trimethylolpropane, and pentaerythritol.

In general, polyether polyols are polyols having a polyether structure, and are ring-opened polymers of one or more active hydrogen-containing compounds having two or more active hydrogens and one or more cyclic ethers.

The polyether polyol used as the polyol (a-1) has no EO group. In the polyether polyol having no EO group, a cyclic ether which does not form an EO group may be used as the cyclic ether of the raw material.

Examples of the active hydrogen-containing compound include compounds having a hydroxyl group, amines, and compounds having a hydroxyl group and an NH group.

Examples of the compound having a hydroxyl group include water, and 2-functional polyols having two hydroxyl groups such as diols (also referred to as diols) (specifically, propylene glycol, 1, 4-butanediol, neopentyl glycol, and butylethylpentanediol); and 3 or more functional polyols having three or more hydroxyl groups such as glycerin, trimethylolpropane, and pentaerythritol.

The amine may be a polyamine such as ethylenediamine, isophoronediamine, or xylylenediamine.

Examples of the compound having a hydroxyl group and an NH group include N-aminoethylethanolamine.

Examples of the cyclic ether not forming an EO group include Alkylene Oxides (AO) other than Ethylene Oxide (EO) such as propylene oxide and butylene oxide; tetrahydrofuran, and the like.

As the polyether polyol having no EO group, an alkylene oxide adduct of an active hydrogen-containing compound (except for an EO adduct) is preferable (also referred to as polyoxyalkylene polyol). Specific examples thereof include 2-functional polyalkylene glycols such as polypropylene glycol (PPG) and polytetramethylene glycol; and polyether polyols having 3 or more functions such as an alkylene oxide adduct of glycerin.

Polycaprolactone polyols are polyols having a polyester structure, and are ring-opened polymers of one or more cyclic esters such as epsilon-caprolactone and sigma-valerolactone. The polyols may be obtained by ring-opening polymerization of one or more cyclic esters.

Polycarbonate polyols are polyols having a carbonate structure. The polyol can be obtained by polycondensation of a polyol with phosgene (phosgene), polycondensation of a polyol with bischloroformate (bischloformate) of a dioxy compound, polycondensation of a polyol with a carbonic acid diester, polycondensation of a polyol with a dicarbonate of a dioxy compound, and the like.

The polyol (a-1) other than the polyether polyol may have an EO group, and the polyol (a-1) is preferably a polyol having no EO group regardless of the kind of the polyol (a-1). That is, the polyol (a-1) is preferably at least one polyol selected from the group consisting of a polyester polyol having no EO group, a polyether polyol having no EO group, a polycaprolactone polyol having no EO group, and a polycarbonate polyol having no EO group. Among these, polyester polyols having no EO group and polyether polyols having no EO group are more preferable.

The number average molecular weight (Mn) of the polyol (a-1) is not particularly limited, and preferred ranges are as follows.

The Mn of the polyester polyol is preferably 500 to 5,000, more preferably 1,000 to 4,000, and particularly preferably 1,000 to 3,000.

The Mn of the polyether polyol having no EO group is preferably 500 to 5,000, more preferably 1,000 to 4,000.

The Mn of the polycaprolactone polyol is preferably 500 to 5,000, more preferably 1,000 to 4,000, particularly preferably 1,000 to 3,000.

The Mn of the polycarbonate polyol is preferably 500 to 5,000, more preferably 1,000 to 4,000, and particularly preferably 1,000 to 3,000.

In the above-mentioned respective polyols, when Mn is not less than the lower limit, gelation of the urethane prepolymer (a) is effectively suppressed, and when Mn is not more than the upper limit, the cohesive force of the urethane prepolymer (a) is suitable.

< polyether polyol (a-2) >

The polyether polyol (a-2) having one or more EO groups in one molecule includes a compound (addition polymer) obtained by addition polymerization of one or more cyclic ethers containing Ethylene Oxide (EO) and an active hydrogen-containing compound. Examples of the active hydrogen-containing compound and the cyclic ether other than Ethylene Oxide (EO) are the same as those of the polyol (a-1).

Examples of the 2-functional polyether polyol having one or more EO groups in one molecule include polyalkylene glycols obtained by addition polymerization of one or more Alkylene Oxides (AO) containing Ethylene Oxide (EO) and an active hydrogen-containing compound having two active hydrogens. The polyalkylene glycol may be polyethylene glycol (PEG) or the like.

Examples of the 3-or more-functional polyether polyol having one or more EO groups in one molecule include compounds (addition polymers) obtained by addition polymerization of one or more Alkylene Oxides (AO) containing Ethylene Oxide (EO) and an active hydrogen-containing compound having three or more active hydrogens. Examples of the 3-or more-functional polyether polyol having one or more EO groups in one molecule include a glycerin EO adduct obtained by addition polymerization of one or more Ethylene Oxides (EO) to glycerin, and a glycerin PO-EO adduct obtained by addition polymerization of one or more Propylene Oxides (PO) and one or more Ethylene Oxides (EO) to glycerin in this order (also referred to as "glycerin polypropylene glycol-terminated ethylene glycol modification").

The number average molecular weight (Mn) of the polyether polyol (a-2) having one or more EO groups in one molecule is not particularly limited, but is preferably 500 to 5,000, more preferably 1,000 to 5,000, particularly preferably 1,500 to 5,000. When Mn is 500 or more, gelation of the urethane prepolymer (a) is effectively suppressed. When Mn is 5,000 or less, the cohesive force of the urethane prepolymer (A) is favorable.

The urethane prepolymer (a) obtained by using the polyether polyol (a-2) having one or more EO groups in one molecule is relatively easily hardened. Therefore, after the adhesive of the present invention is applied to a substrate sheet, the coating layer is cured relatively quickly, and thick film coating is easy. Further, even if thick film coating is performed, the coating layer is cured relatively quickly, and therefore the coating layer and the adhesive layer are less likely to be affected by hot air during heat drying of the coating layer, mechanical stress applied during winding of the adhesive sheet obtained after heat drying, or the like. Therefore, defects such as roll marks and distortion are suppressed, and an adhesive layer having excellent surface smoothness can be formed. The adhesive layer can be formed in a thick film, and thus an adhesive layer having excellent impact resistance and excellent functions of protecting adherends such as various optical members from impact, vibration, and the like can be formed.

In addition, in general, when the adhesive layer is exposed to a high-temperature and high-humidity environment, cloudiness (whitening) may occur. EO groups are hydrophilic groups. By using the urethane prepolymer (a) obtained by using the polyether polyol (a-2) having one or more EO groups in one molecule, the hydrophilicity of the adhesive layer is improved, and the whitening due to moist heat can be suppressed. The increase in hydrophilicity of the adhesive layer is likely to cause moisture transfer between the adhesive layer and the external environment, and even if moisture enters the adhesive layer from the outside, it is likely to cause moisture 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.

Further, the urethane prepolymer (a) obtained by using the polyether polyol (a-2) having one or more EO groups in one molecule is slightly conductive, and therefore an adhesive layer using the same can realize a low surface resistance value and slightly antistatic properties. However, the inventors have found that the urethane prepolymer (a) alone does not exhibit antistatic properties to such an extent that dust adhesion to the adhesive layer can be effectively suppressed. When the urethane prepolymer (a) and the β -diketone compound (X) are used in combination, the surface resistance value of the adhesive layer is effectively reduced and antistatic properties are effectively exhibited, and dust adhesion to the surface of the adherend after peeling off the adhesive layer can be effectively suppressed.

As the polyol (a-1), any of a 2-functional polyol having two hydroxyl groups and a 3-functional or higher polyol having three or more hydroxyl groups can be used. These may be used in combination.

Similarly, as the polyol (a-2), any of a 2-functional polyol having two hydroxyl groups and a 3-functional or higher polyol having three or more hydroxyl groups can be used. These may be used in combination.

In general, the 2-functional polyol has two-dimensional crosslinkability and can impart appropriate flexibility to the adhesive layer. The 3-or more-functional polyol has three-dimensional crosslinkability and can impart an appropriate hardness to the adhesive layer.

The properties of the urethane adhesive of the present invention, such as adhesion, cohesion, and removability, can be adjusted by selecting the number of hydroxyl groups of the one or more polyols (a-1) and the number of hydroxyl groups of the one or more polyols (a-2). In terms of easy achievement of both adhesive strength and removability, it is preferable that at least one of the plurality of polyols (a) is a polyol having 3 or more functions.

The mass ratio of the one or more polyether polyols (a-1) to the one or more polyether polyols (a-2) is not particularly limited. The total amount of the one or more polyols (a-1) and the one or more polyether polyols (a-2) is set to 100 parts by mass. The amount of the one or more polyether polyols (a-1) is preferably more than 0 part by mass and 50 parts by mass or less, more preferably 20 parts by mass to 50 parts by mass. The amount of the one or more polyether polyols (a-2) is preferably 50 parts by mass or more and less than 100 parts by mass, and more preferably 50 parts by mass to 80 parts by mass. When the amount of the one or more polyether polyols (a-2) is 50 parts by mass or more, the wet-heat whitening resistance and the antistatic property can be effectively exhibited. When the amount of the one or more polyols (a-1) is more than 0 part by mass, the effect of thick film coatability can be effectively exhibited.

< polyisocyanate (b) >

Examples of the polyisocyanate (b) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

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, 4 '-triphenylmethane triisocyanate, omega' -diisocyanate-1, 3-dimethylbenzene, omega '-diisocyanate-1, 4-dimethylbenzene, omega' -diisocyanate-1, 4-diethylbenzene, 1, 4-tetramethylxylene diisocyanate, 1, 3-tetramethylxylene diisocyanate, and the like.

Examples of the aliphatic polyisocyanate include: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1, 2-propylene diisocyanate, 2, 3-butylene diisocyanate, 1, 3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4, 4-trimethylhexamethylene diisocyanate, 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, examples of the polyisocyanate (b) include trimethylolpropane adduct, biuret (biuret) adduct, and trimer (the trimer includes an isocyanurate ring) of the above polyisocyanate.

The polyisocyanate (b) is preferably an aliphatic polyisocyanate or an alicyclic polyisocyanate, and more preferably an aliphatic polyisocyanate.

In the polymerization of the urethane prepolymer (a), it is preferable that a plurality of polyols (a) (specifically, a combination of one or more polyols (a-1) and one or more polyether polyols (a-2)) and one or more polyisocyanates (b) are reacted at a ratio such that the functional group ratio (NCO/OH ratio) of the number of moles of hydroxyl groups (OH) in the plurality of polyols (a) to the number of moles of isocyanate groups (NCO) in the one or more polyisocyanates (b) is 0.5 to 0.9.

< catalyst >

If necessary, one or more catalysts may be used for the polymerization of the urethane prepolymer (A). 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-based compound include: dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate (dibutyl tin dimaleate), dibutyltin dilaurate (DBTDL), dioctyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide (tributyltin ethoxide), tributyltin ethoxide (tributyltin ethoxide), dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate, and the like.

Examples of the non-tin compound include: titanium compounds such as dibutyltitanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; iron compounds such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc compounds such as zinc naphthenate and zinc 2-ethylhexanoate; zirconium naphthenate and bismuth carboxylate.

When the reactivity of the plural kinds of polyols (a) are different from each other, gelation or clouding of the reaction solution may easily occur in a single catalyst system due to the difference in reactivity. In such a case, the use of two or more catalysts makes it easy to control the reaction (for example, reaction rate), and the above problems can be solved, and the degree of freedom in selecting the polyol (a) is increased. That is, in the present invention, it is preferable to use two or more catalysts.

The combination of two or more catalysts is not particularly limited, and examples thereof include tertiary amine/organic metal-based catalysts, tin-based catalysts/non-tin-based catalysts, and tin-based catalysts/tin-based catalysts. Tin-based/tin-based is preferred, and dibutyltin dilaurate/tin 2-ethylhexanoate is more preferred.

The mass ratio of 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 less than 1, the balance of the catalyst activity is good, and gelation can be effectively suppressed.

The amount of the one or more catalysts used is not particularly limited, but is preferably 0.01 to 1% by mass based on the total amount of the plurality of polyols (a) and the one or more polyisocyanates (b).

< solvent >

If necessary, one or more solvents may be used for the polymerization of the urethane prepolymer (A). As the solvent, known ones can be used, and there can be mentioned: ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; aromatic hydrocarbons such as toluene and xylene. From the viewpoints of solubility of the urethane prepolymer (a), boiling point of the solvent, and the like, ethyl acetate, toluene, and the like are preferable.

< polymerization Process >

The polymerization method of the urethane prepolymer (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 (a), one or more polyisocyanates (b), optionally one or more catalysts, and optionally one or more solvents are mixed together and then reacted;

sequence 2) mixing a plurality of polyols (a), optionally one or more catalysts, and optionally one or more solvents, and reacting the mixture while adding one or more polyisocyanates (b).

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 deg.C, more preferably 85 deg.C to 95 deg.C. When the reaction temperature is less than 100 ℃, the reaction rate, the crosslinked structure, and the like can be easily controlled, and the urethane prepolymer (a) having a desired molecular weight can be easily produced.

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

The urethane prepolymer (A) preferably has a weight average molecular weight (Mw) of 3 to 50 ten thousand, more preferably 5 to 40 ten thousand, and a molecular weight distribution (Mw/Mn) of 4 to 12, more preferably 6 to 10, from the viewpoint of good coatability of the self-adhesive.

(beta-diketone compound (X))

The adhesive of the present invention may contain one or more β -diketone compounds (X) in embodiment 1.

The β -diketone compound (X) is not particularly limited, and includes: 2, 4-pentanedione, 3-methyl-2, 4-pentanedione, 2, 4-hexanedione, 1, 3-cyclohexanedione, 2-dimethyl-3, 5-hexanedione, 2, 4-heptanedione, 3, 5-heptanedione, 2,6, 6-tetramethyl-3, 5-heptanedione, 1, 3-cycloheptanedione, 2, 4-octanedione, 2, 7-trimethyl-3, 5-octanedione, 2, 4-nonanedione, 3-methyl-2, 4-nonanedione, 2-methyl-4, 6-nonanedione, 1-phenyl-1, 3-butanedione, and spirodecanedione, and the like. Among them, 2, 4-pentanedione, 2-dimethyl-3, 5-hexanedione and the like are preferable.

The β -diketone compound (X) also easily forms an enol form in a keto-enol tautomer, and thus has dielectric polarization and thus has slight conductivity. Therefore, an adhesive layer comprising the compound can realize a low surface resistance value and a slight antistatic property. However, the findings of the present inventors have revealed that the β -diketone compound (X) alone does not exhibit antistatic properties to such an extent that dust adhesion to the adhesive layer can be effectively suppressed. By using the urethane prepolymer (a) having one or more EO groups and the β -diketone compound (X) in combination, the surface resistance value of the adhesive layer is effectively reduced and the antistatic property is effectively exhibited, and the adhesion of dust to the adhesive layer can be effectively suppressed.

The amount of the one or more β -diketone compounds (X) added is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 10 parts by mass, particularly preferably 0.1 to 5 parts by mass, most preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the one or more urethane prepolymers (a). When the amount is 0.01 part by mass or more, the effect of suppressing the adhesion of dust to the adhesive layer can be effectively exhibited. When the amount is 10 parts by mass or less, the amount of the urethane prepolymer (a) which is a main active ingredient of the adhesive which is essentially required can be sufficiently secured, and the performance required as the adhesive can be secured.

(fatty acid ester (B))

The adhesive of the present invention may contain one or more fatty acid esters (B) in embodiment 2. The fatty acid ester (B) functions as a plasticizer and improves the wettability of the adhesive layer. The fatty acid ester (B) increases the hydrophobicity of the adhesive layer, particularly the surface layer portion on the adherend side of the optical member of the adhesive layer, and when the adhesive sheet is exposed to a high-temperature and high-humidity environment, it is possible to suppress the intrusion of moisture into the adhesive layer from the external environment, thereby suppressing the clouding (whitening) of the adhesive layer.

The fatty acid ester (B) is not particularly limited, and is preferably an ester obtained by the reaction of a C8-18 monobasic or polybasic acid with a C18 or less branched alcohol; and esters obtained by reacting unsaturated fatty acids having 14 to 18 carbon atoms with alcohols having a hydroxyl number of 4 or less.

Examples of the ester obtained by the reaction of a C8-18 monobasic or polybasic acid with 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, trioleyl trimellitate, and triisocetyl trimellitate. Among these, isopropyl myristate, isocetyl myristate, and octyldodecyl myristate are preferable, and isopropyl myristate is particularly preferable.

Examples of the unsaturated fatty 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 alcohol having a hydroxyl number of 4 or less include: ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitan, and the like.

The number average molecular weight (Mn) of the fatty acid ester (B) is not particularly limited, and is preferably 200 or more, and preferably 600 or less from the viewpoint of improvement in the wetting rate and the like.

The amount of the one or more fatty acid esters (B) to be added is not particularly limited, but is preferably 5 to 50 parts by mass, more preferably 20 to 40 parts by mass, per 100 parts by mass of the one or more urethane prepolymers (a). When the amount is 5 parts by mass or more, the effect of adding the fatty acid ester (B) (wettability-improving effect) can be effectively exhibited. When the amount is 50 parts by mass or less, the amount of the urethane prepolymer (a) which is a main active ingredient of the adhesive which is originally necessary can be sufficiently secured, and the performance necessary as the adhesive can be secured.

The urethane adhesive of the present invention may be the combination of embodiment 1 and embodiment 2, as embodiment 3. That is, the urethane adhesive of the present invention may be embodiment 3 including the urethane prepolymer (a), the β -diketone compound (X), and the fatty acid ester (B).

(isocyanate hardener (I))

The adhesive of the present invention may optionally contain one or more isocyanate hardeners (I). The coating layer containing the adhesive of the present invention is a cured film obtained by curing the urethane prepolymer (a) with the isocyanate curing agent (I).

As the isocyanate curing agent (I), known ones can be used, and compounds exemplified for the polyisocyanate (b) which is a raw material of the urethane prepolymer (a) (specifically, aromatic polyisocyanate, aliphatic polyisocyanate, aromatic aliphatic polyisocyanate, alicyclic polyisocyanate, and trimethylolpropane adduct/biuret/trimer thereof) can be used.

The content of the one or more isocyanate curing agents (I) in the urethane adhesive of the present invention is not particularly limited, and is preferably 3 to 30 parts by mass, more preferably 10 to 20 parts by mass, based on 100 parts by mass of the one or more urethane prepolymers (a). When the content is 3 parts by mass or more, the cohesive force of the adhesive layer is good, and when the content is 30 parts by mass or less, the adhesive force of the adhesive layer is good.

(hardening accelerator)

The adhesive of the present invention may optionally contain one or more hardening accelerators. As the hardening accelerator, known ones can be used, and examples thereof include catalysts listed in the synthesis of the urethane prepolymer (a).

The amount of the one or more curing accelerators is not particularly limited, but is preferably 0.0005 to 0.5 parts by mass, more preferably 0.001 to 0.1 parts by mass, particularly preferably 0.003 to 0.05 parts by mass, and most preferably 0.005 to 0.03 parts by mass, based on 100 parts by mass of the urethane prepolymer (a), from the viewpoint of effective curing acceleration.

(solvent)

The adhesive of the present invention may optionally contain more than one solvent. As the solvent, known ones can be used, and examples thereof include acetone, methyl ethyl ketone, ethyl acetate, toluene, xylene, and the like. Ethyl acetate, toluene and the like are particularly preferable from the viewpoints of solubility of the urethane prepolymer (a), boiling point of the solvent and the like.

(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: any resin other than the urethane prepolymer (a), a hardening retarder, a filler, a metal powder, a colorant, 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.

< Filler >

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

< antioxidant >

Examples of the antioxidant include a radical chain inhibitor (primary antioxidant) and a peroxide decomposer (secondary antioxidant). Examples of the radical chain inhibitor (primary antioxidant) include phenol antioxidants and amine antioxidants. Examples of the peroxide decomposer (secondary antioxidant) include a sulfur-based antioxidant and a phosphorus-based antioxidant.

Examples of the phenolic antioxidant include monophenol antioxidants, bisphenol antioxidants, and high-molecular phenol antioxidants. Examples of the monophenol antioxidant include: 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.

As the bisphenol-based antioxidant, there may be mentioned: 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- [ beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy ] ethyl ]2,4,8, 10-tetraoxaspiro [5,5] undecane, and the like.

Examples of the polymeric phenol antioxidant include: 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, Tocopherols, and the like. For example, xylosus (IRGANOX) L135 (manufactured by BASF) is preferable in terms of good compatibility with the urethane prepolymer (a).

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.

Process for producing urethane adhesive "

The urethane adhesive of the present invention can be produced by a known method.

The urethane adhesive of embodiment 1 is preferably usable

A urethane prepolymer (A) obtained by reacting one or more polyols (a-1) other than a polyether polyol having one or more ethyleneoxy groups in one molecule, one or more polyether polyols (a-2) having one or more ethyleneoxy groups in one molecule, and one or more polyisocyanates (b), and

The urethane adhesive of embodiment 2 is preferably usable

a fatty acid ester (B) in a predetermined ratio.

Adhesive sheet "

The adhesive sheet of the present invention includes an adhesive layer containing a cured product of the adhesive of the present invention. The adhesive sheet of the present invention preferably includes 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 surface or both surfaces of the substrate sheet. The exposed surface of the adhesive layer may be covered with a release sheet (also referred to as a release liner) if necessary. 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 on which 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 manufactured 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 urethane 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 urethane adhesive of the present invention. The heating and drying temperature is not particularly limited, but is preferably about 60 ℃ to 150 ℃.

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.

The urethane adhesive of the present invention can be suitably used for both thin film coating and thick film coating, and has a higher degree of freedom in designing the thickness of the adhesive layer than before. The thickness of the adhesive layer can be suitably designed according to the use of the adhesive sheet, and can be the former level (5 μm to 30 μm), or can be a thick film level of 30 μm or more, which has been difficult before. By making the adhesive layer thick, an adhesive layer having excellent impact resistance and excellent functions of protecting an adherend from impact, vibration, and the like can be formed. The upper limit of the thickness of the adhesive layer is not particularly limited, and is about 200 μm since an adhesive layer having good surface smoothness can be formed. The thickness of the adhesive layer is preferably from 30 to 200. mu.m, more preferably from 40 to 150. mu.m, particularly preferably from 50 to 150 μm, from the viewpoint of improvement in impact resistance and surface smoothness. In the present specification, the "thickness of the adhesive layer" is a thickness after drying unless otherwise specified.

As described above, by using the adhesive of embodiment 1 of the present invention containing the urethane prepolymer (a) and the β -diketone compound (X), the surface resistance value of the adhesive layer is reduced, the antistatic property is improved, and the adhesion of dust to the adhesive sheet can be effectively suppressed. The antistatic property can be evaluated by the surface resistance value.

The surface resistance value of the adhesive layer obtained using the urethane adhesive of the present invention is preferably less than 1.0 × 10¹¹(omega/□). When the surface resistance value is at the above level, adhesion of dust can be effectively suppressed. The "surface resistance value" can be measured by the method described in "example".

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.

The adhesive sheet of the present invention can be suitably used as a surface protective sheet for various displays (flat panel displays, touch panel displays, and the like), substrates manufactured or used in the manufacturing steps thereof, optical members, and the like.

As described above, according to the present invention, a urethane adhesive that can be thick-film coated and can form an adhesive layer having excellent resistance to wet-heat whitening, and an adhesive sheet using the same can be provided.

The adhesive according to embodiment 2 of the present invention containing the urethane prepolymer (a) and the fatty acid ester (B) has good wettability, can be applied in a thick film, and can form an adhesive layer having good resistance to wet whitening by heat.

Display unit "

The display of the present invention includes an adhesive layer containing a cured product of the adhesive of the present invention. The display of the present invention may preferably comprise an adhesive sheet including an adhesive layer containing a cured product of the adhesive of the present invention.

Examples of the display include a flat panel display such as a Liquid Crystal Display (LCD) and an organic electroluminescence display (ELD), and a touch panel display in which the flat panel display and a touch panel are combined.

[ 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 Mw, Mn, Mw/Mn"

The weight average molecular weight (Mw), the number average molecular weight (Mn), and the molecular weight distribution (Mw/Mn) are 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),

Pipe column: 3 Soidex LF-804 (manufactured by Showa Denko K.K.) were connected in series,

A detector: a differential refractive index detector,

Solvent: tetrahydrofuran (THF),

Flow rate: 0.5mL/min,

Temperature of the solvent: at 40 deg.C,

Sample concentration: 0.1 percent,

Sample injection amount: 100 μ L.

[ Material ]

The materials used are as follows.

< polyol (a-1) >

(a-1-1): a Polyol having 2 functional groups and no EO groups (Kuraray Polyol) P-1010 (manufactured by Kuraray Co., Ltd.), Mn1000, and a hydroxyl number of 2;

(a-1-2): kuraray Polyol P-2010 (manufactured by Coly corporation), 2-functional polyester Polyol having no EO group, Mn2000, hydroxyl number 2;

(a-1-3): kuraray Polyol P-3010 (manufactured by Coloray), 2-functional polyester Polyol having no EO group, Mn3000, hydroxyl number 2;

(a-1-4): sannesius (Sannix) GP-1500 (manufactured by Sanyo chemical industries), a 3-functional polyether polyol having no EO group, Mn1500, a hydroxyl number of 3;

(a-1-5): sannix PP-2000 (manufactured by sanyo chemical industries), 2-functional polyether polyol having no EO group, Mn2000, hydroxyl number 2;

(a-1-6): sannix GP-3000 (manufactured by sanyo chemical industries), 3-functional polyether polyol having no EO group, Mn3000, hydroxyl number 3;

(a-1-7): prassel (Placcel)220N (manufactured by Daicel corporation), 2-functional polycaprolactone polyol having no EO group, Mn2000, hydroxyl number 2;

(a-1-8): desmodium model (Desmophen)2020E (manufactured by Sumika Bayer Urethane), 2-functional polycarbonate polyol having no EO group, Mn2000, hydroxyl number 2;

(a-1-9): praminole (prominol) S4006 (manufactured by asahi glass company), 2-functional polyether polyol having no EO group, Mn5500, hydroxyl number 2;

(a-1-10): EDP-1100 (manufactured by Adeka corporation), 4-functional polyether polyol having no EO group, Mn1100, and hydroxyl number 4.

< polyether polyol (a-2) having EO group >

(a-2-1): adico polyether (ADEKA polyether) AM-302 (made by adico), 3-functional polyether polyol, glycerol PO · EO adduct, Mn3000, hydroxyl number 3;

(a-2-2): ADEKA polyether GR-3308 (manufactured by Ediko corporation), 3-functional polyether polyol, glycerol PO. EO adduct, Mn3400, hydroxyl number 3.

< polyisocyanate (b) >

(b-1): hexamethylene diisocyanate (manufactured by Tosoh corporation);

(b-2): takenate (registered trademark) 500 (manufactured by Mitsui chemical Co., Ltd.), 1, 3-xylene diisocyanate.

< fatty acid ester (B) >)

(B-1): nicol (NIKKOL) IPP (manufactured by Nikko Chemicals), isopropyl palmitate;

(B-2): NIKKOL IPM-100 (manufactured by Nikkol chemical Co., Ltd.), isopropyl myristate.

< beta-diketone compound (X) >

(X-1): 2, 4-pentanedione;

(X-2): 2, 2-dimethyl-3, 5-hexanedione.

< isocyanate hardener (I) >)

(I-1): crotonate HL (manufactured by tokyo corporation), hexamethylene diisocyanate/trimethylolpropane adduct;

(I-2): sumitor (Sumidur) N-3300 (manufactured by Sumitor Bayer urethanes), hexamethylene diisocyanate/isocyanurate;

(I-3): coronate L (manufactured by tokyo corporation), toluene diisocyanate/trimethylolpropane.

[ Synthesis of urethane prepolymer (A) ]

(Synthesis example 1)

50 parts of polyester polyol (a-1-1) and 850 parts of polyether polyol (a-2-1) having one or more EO groups were added to a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a thermometer, and a dropping funnel. To this was added 650 parts of toluene. Further, 0.25 part of dibutyltin dilaurate and 0.1 part of tin 2-ethylhexanoate were added as catalysts. The temperature was gradually raised to 90 ℃ under a nitrogen atmosphere, and an amount (48 parts) of polyisocyanate (b-1) such that the NCO/OH ratio (functional group ratio) became 0.6 was added dropwise thereto, followed by carrying out a reaction for 2 hours. After disappearance of the remaining isocyanate groups was confirmed by infrared absorption (IR) spectroscopy, the reaction solution was cooled to complete the reaction, thereby obtaining a solution of urethane prepolymer (A-1) (nonvolatile content: 60%). The weight-average molecular weight (Mw) of the obtained urethane prepolymer (A-1) was 78,000.

The kinds of the polyol (a) and the polyisocyanate (b) used and their blending ratio, and the Mw of the obtained urethane prepolymer are shown in Table 1-1. In Table 1-1, the unit of the amount of polyol (a) blended is [ part ], and the amount of polyisocyanate (b) blended is expressed in terms of NCO/OH ratio (functional group ratio) (the same applies to tables 1-2 to 1-5).

The amount of the polyisocyanate (b-1) was calculated according to the following formula (the same applies to other synthesis examples).

(amount of (b-1) ([ part ] ═ part)

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

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

+ ((part weight of (x 2-1)/((x 2-1) × ((x 2-1))

＝0.6×168.2/2×(50/1000×2+850/3000×3)

＝48

(Synthesis examples 2 to 22)

Synthesis examples 2 to 22 were carried out in the same manner as in Synthesis example 1 except that the types of polyol (a) and polyisocyanate (b) used and the blending ratio thereof were changed as shown in tables 1-1 to 1-5, thereby obtaining urethane prepolymers (A-1) to (A-19) and urethane prepolymers (D-1) to (D-3) for comparison. The Mw of the urethane prepolymer obtained in each synthesis example and the nonvolatile matter concentration of the urethane prepolymer solution are shown in tables 1-1 to 1-5.

[ example 1]

100 parts of the urethane prepolymer (A-1) obtained in Synthesis example 1, 30 parts of a fatty acid ester (B-1), 0.3 part of an antioxidant "IRGANOX L135" (manufactured by BASF), 0.3 part of an ultraviolet absorber "Dennubin (TINUVIN) 571" (manufactured by BASF), 0.3 part of a light stabilizer "Dennubin (TINUVIN) 765" (manufactured by BASF), 15 parts of an isocyanate curing agent (I-1), and 100 parts of ethyl acetate as a solvent were blended and stirred by a disperser, thereby obtaining a urethane adhesive. The amounts of the respective materials other than the solvent used are expressed as nonvolatile components (the same applies to other examples and comparative examples). The kinds and blending ratios of the materials used are shown in Table 2-1.

[ examples 2 to 26]

Urethane adhesives were obtained in the same manner as in example 1, except that in examples 2 to 26, the kinds and blending ratios of the materials used were changed as shown in tables 2-1 to 2-4 and tables 3-1 to 3-2.

Comparative examples 1 to 3

Urethane adhesives were obtained in the same manner as in example 1, except that the types and blending ratios of the materials used in comparative examples 1 to 3 were changed as shown in tables 2 to 5 and 3 to 3.

Comparative example 4

100 parts of the urethane prepolymer (A-2) obtained in Synthesis example 2, 20 parts of "Mozizer W-260" (manufactured by Diesen (DIC) Co., Ltd., polyalkylene glycol compound) as a hydrophilic additive, 0.3 part of antioxidant "IRGANOX L135" (manufactured by Pasteur Co., Ltd.), 0.3 part of ultraviolet absorber "TINUVIN 571" (manufactured by Pasteur Co., Ltd.), 0.3 part of light stabilizer "TINUVIN 765" (manufactured by Pasteur Co., Ltd.), 15 parts of isocyanate curing agent (I-1) and 100 parts of ethyl acetate as a solvent were blended and stirred by a disperser to obtain a urethane adhesive. The kinds and blending ratios of the materials used are shown in tables 2 to 5.

Comparative example 5

A urethane adhesive was obtained by blending 70 parts of a polyether polyol (a-1-9), 18 parts of a polyether polyol (a-1-4), 12 parts of a polyether polyol (a-1-10), 0.006 part of a β -diketone compound (X-1), 0.04 part of "Nacem Ferric Iron" (manufactured by japan chemical industries, inc., tris (acetylacetonato) Iron) "as a catalyst, 40 parts of an isocyanate curing agent (I-3), and 150 parts of ethyl acetate as a solvent, and stirring the blend with a disperser.

In comparative example 5, 3 kinds of polyols were used as they were instead of the urethane prepolymer. The kinds and blending ratios of the materials used are shown in tables 3 to 3.

[1 th evaluation production and evaluation of adhesive sheet (Release sheet/adhesive layer/base sheet) ]

In each of examples 1 to 26 and comparative examples 1 to 5, the adhesive sheet for evaluation 1 (release sheet/adhesive layer/base sheet) was obtained as follows.

A polyethylene terephthalate (PET) sheet (Lumiler T-60, manufactured by Toray corporation) having a thickness of 50 μm was prepared as a substrate sheet. The obtained urethane adhesive was applied to one surface of a substrate sheet at a coating speed of 30m/min using a comma coater (registered trademark) so that the thickness after drying became 80 μm. The formed coating layer was dried at 100 ℃ for 2 minutes to form a bonding layer. The adhesion layer thus formed was evaluated for suitability for thick film coating.

Then, a release sheet (Super Stik) SP-PET38, Lintec) having a thickness of 38 μm was attached to the adhesive layer formed, and cured for one week at 23 ℃ and 50% RH to obtain an adhesive sheet for evaluation 1 (release sheet/adhesive layer/base sheet). The adhesive sheet for evaluation 1 was evaluated for adhesive strength, resistance to wet-heat whitening, wettability, and surface resistance. In the present specification, "RH" represents relative humidity.

[ production and evaluation of adhesive sheet for evaluation (No. 2 Release sheet/adhesive layer/No. 1 Release sheet) ]

In each of examples 1 to 26 and comparative examples 1 to 5, the adhesive sheet for evaluation (release sheet/adhesive layer/release sheet) of example 2 was obtained as follows.

The obtained urethane adhesive was applied to a 1 st release sheet (Film binding) 50E0010-DG3, manufactured by Tenson industries, having a thickness of 50 μm at a coating speed of 3m/min so that the thickness after drying became 80 μm using a comma coater (registered trademark). The formed coating layer was dried at 100 ℃ for 2 minutes to form a bonding layer. A2 nd release sheet (Super Stik SP-PET38, Lindcao) having a thickness of 38 μm was attached to the adhesive layer, and cured at 23 ℃ and 50% RH for 30 minutes to obtain a 2 nd evaluation adhesive sheet (2 nd release sheet/adhesive layer/1 st release sheet). The 2 nd evaluation adhesive sheet was evaluated for gel fraction.

[ evaluation items and evaluation methods ]

(adhesion)

A measurement sample having a width of 25mm and a length of 100mm was cut out from the adhesive sheet for evaluation No. 1. The release sheet was peeled from the test sample at 23 ℃ and 50% RH, and the exposed surface of the adhesive layer was adhered to a stainless steel plate (SUS304), and the resultant was pressed with a 2kg roller from the base sheet side, and then left to stand for 24 hours. Thereafter, the adhesion of the adhesive layer was measured using a tensile tester at a peel speed of 300mm/min and a peel angle of 180 ℃ in accordance with Japanese Industrial Standards (JIS) Z0237. The evaluation criteria are as follows.

O: less than 20mN/25mm, good.

And (delta): 20mN/25 mm-100 mN/25mm, and is practical.

X: more than 100mN/25mm, it is not practical.

(resistance to Wet Heat whitening)

A measurement sample having a width of 25mm and a length of 100mm was cut out from the adhesive sheet for evaluation No. 1. The release sheet was peeled from the test sample at 23 ℃ and 50% RH, and the exposed surface of the adhesive layer was attached to a glass plate and left to stand for 1 hour. The resultant was left to stand in an atmosphere of 60 ℃ 90% RH for 72 hours and in an atmosphere of 23 ℃ 50% RH for 1 hour, and then haze (haze) was measured in accordance with JIS K7136 using a haze meter NDH5000W (manufactured by Nippon Denshoku industries Co., Ltd.). The evaluation criteria are as follows.

O: haze less than 2%, good.

And (delta): haze is less than 5%, and the method is practical.

X: haze was 5% or more, and it was not practical.

(wettability)

A measurement sample having a width of 100mm and a length of 200mm was cut out from the adhesive sheet for evaluation No. 1. The measurement sample was left to stand in an atmosphere of 23 ℃ 50% RH for 30 minutes, and then the release sheet was peeled off from the measurement sample. Then, both ends of the adhesive sheet in the longitudinal direction are held with both hands, and the center portion of the exposed surface of the adhesive layer is brought into contact with the glass plate, and then both hands are released. The time until the entire adhesive layer was brought into close contact with the glass plate by the weight of the adhesive sheet was measured, and the wettability to glass was evaluated. The shorter the time until the glass plate comes into close contact with, the better the affinity for glass, and therefore the glass member can be easily protected in the production steps of various optical members and the like using the glass member. The evaluation criteria are as follows.

O: less than 3 seconds, good.

And (delta): it is practical for 3 seconds or more and less than 5 seconds.

X: 5 seconds or more, it is not practical.

(suitability for Thick film coating)

In the production step of the adhesive sheet for evaluation 1, the surface of the formed adhesive layer was visually observed with the following criteria at the stage before the release sheet was attached. The evaluation criteria are as follows.

O: the surface is smooth and good.

And (delta): unevenness is observed on the surface, and it is practical.

X: the surface was observed to have a roll mark or skew, and was not practical.

(gel fraction (Thick film coating suitability))

The gel fraction was measured as an index of suitability for thick film coating. If the adhesive layer is maintained in a high-fluidity state for a long time before complete curing during curing, the surface smoothness may decrease. When the adhesive layer obtained after the heat drying treatment has a high gel fraction in a short time, the adhesive layer is cured quickly and suitable for thick film coating.

A measurement sample having a width of 30mm and a length of 100mm was cut out from the adhesive sheet for evaluation No. 2. Next, the 1 st release sheet was peeled off from the test sample, and the surface of the exposed adhesive layer was attached to a 200-mesh gold mesh. Further, after the 2 nd release sheet was peeled off, the entire adhesive layer was surrounded by the gold mesh. The mass of the structure was measured, and the mass of the gold mesh was subtracted to determine the initial mass of the adhesive layer. Then, the structure was immersed in a closed container containing 250g of ethyl acetate at 50 ℃ for 24 hours, and then taken out. The structure was dried at 100 ℃ for 30 minutes, and then the mass was measured again, and the mass of the gold mesh was subtracted to determine the mass of the adhesive layer. The gel fraction was determined by the following calculation.

(gel fraction) (%) (mass of adhesive layer after immersion drying)/(mass of adhesive layer before immersion) × 100

The evaluation criteria are as follows.

O: 60% by mass or more is preferable.

And (delta): 40% by mass or more and less than 60% by mass, and is practical.

X: less than 40% by mass, it is not practical.

(surface resistance value)

The surface resistance value was measured as an index of dust adhesion. A measurement sample having a width of 100mm and a length of 100mm was cut out from the adhesive sheet for evaluation No. 1. Then, the measurement sample was left to stand in an atmosphere of 23 ℃ 50% RH for 30 minutes, and then the release sheet was peeled off from the measurement sample. The surface resistance value (Ω/□) was measured by using a resistivity meter Hiresta (Hiresta) UX MCP-HT800 (manufactured by Mitsubishi analysis) with the measurement terminal in contact with the exposed surface of the adhesive layer. The evaluation criteria are as follows.

O: is less than1.0×10¹¹Ω/□, good (level of effectively suppressing dust adhesion).

△：1×10¹¹Omega/□ is more than or equal to and less than 1.0 multiplied by 10¹²Omega/□, can be used practically.

×：1×10¹²Omega/□ or more, and is not practical.

[ evaluation results ]

The evaluation results of examples 1 to 26 and comparative examples 1 to 5 are shown in tables 2-1 to 2-5 and tables 3-1 to 3-3.

In the examples 1 to 19, the following examples were conducted,

producing a urethane prepolymer (A) which is a reaction product of one or more polyols (a-1) other than polyether polyols having one or more EO groups in one molecule, one or more polyether polyols (a-2) having one or more EO groups in one molecule, and one or more polyisocyanates (b); and

a urethane adhesive of a fatty acid ester (B).

In the examples 20 to 22, the following examples,

a urethane adhesive containing a beta-diketone compound (X).

In the examples 23 to 26,

producing a urethane prepolymer (A) which is a reaction product of one or more polyols (a-1) other than polyether polyols having one or more EO groups in one molecule, one or more polyether polyols (a-2) having one or more EO groups in one molecule, and one or more polyisocyanates (b);

a β -diketone compound (X); and

a urethane adhesive of a fatty acid ester (B).

The adhesive sheets obtained in examples 1 to 26 all had good or relatively good results in all the evaluation items of adhesive force, resistance to wet-heat whitening, wettability, suitability for thick film coating, gel fraction, and surface resistance value.

The adhesive sheets obtained in examples 20 to 26, which were produced using the urethane adhesive containing the urethane prepolymer (a) and the β -diketone compound (X), had a significantly reduced surface resistance value of the adhesive layer compared to the other examples, and the surface resistance value was at a level effective for suppressing dust adhesion.

In each of examples 1 to 26, the adhesive sheet was produced and evaluated in the same manner as in the case where the film thickness of the adhesive layer was 80 μm, except that the film thickness of the adhesive layer was changed from 80 μm to 10 μm and 30 μm, and the same evaluation results were obtained as in the case where the film thickness of the adhesive layer was 80 μm.

In comparative examples 1 to 3,

producing a urethane prepolymer (D) for comparison (a reaction product of one or more polyols (a-1) other than a polyether polyol having one or more EO groups in one molecule and one or more polyisocyanates (b) (without using a polyether polyol (a-2) having one or more EO groups in one molecule); and

a urethane adhesive of a fatty acid ester (B).

The adhesive sheets obtained in comparative examples 1 to 3 all had low hydrophilicity and curing properties of the adhesive layer, and were poor in the evaluation items of wet-heat whitening resistance, thick film coating suitability, gel fraction, and surface resistance value.

In the case of comparative example 4, the following examples were conducted,

a urethane adhesive which comprises a urethane prepolymer (A) which is a reaction product of one or more polyols (a-1) other than polyether polyols having one or more EO groups in one molecule, one or more polyether polyols (a-2) having one or more EO groups in one molecule, and one or more polyisocyanates (B) and which does not contain any of a beta-diketone compound (X) and a fatty acid ester (B), is produced.

In comparative example 4, a polyalkylene glycol compound was added as a hydrophilic additive to a urethane adhesive, but the effect of improving hydrophilicity was not sufficient. The reason is not necessarily clear, but there is a possibility that the hydrophobic site of the additive is surface-oriented. Therefore, the obtained adhesive sheet was poor in the evaluation of resistance to wet-heat whitening.

Further, since the amount of the hydrophilic additive added was large, even when the same urethane prepolymer (a) as in examples 1 to 26 was used, the curability was poor, and the obtained adhesive sheet was poor in the evaluation items of the suitability for thick film coating and the gel fraction.

In comparative example 5, a urethane adhesive containing 3 types of polyether polyols having no EO group and a β -diketone compound (X) was produced without urethane prepolymer.

The adhesive sheet obtained in comparative example 5 had a low hydrophilicity and curability of the adhesive layer, and was poor in the evaluation items of the adhesive strength, the resistance to wet-heat whitening, the suitability for thick film coating, and the gel fraction. In addition, the adhesive sheet obtained in comparative example 5, which did not use the urethane prepolymer (a) having an EO group, even when the β -diketone compound (X) was used, was poor in the evaluation items of the surface resistance value.

[ tables 1-1]

[ tables 1-2]

[ tables 1 to 3]

[ tables 1 to 4]

[ tables 1 to 5]

[ Table 2-1]

[ tables 2-2]

[ tables 2 to 3]

[ tables 2 to 4]

[ tables 2 to 5]

[ Table 3-1]

[ tables 3-2]

[ tables 3 to 3]

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.

This application claims priority based on japanese patent application No. 2015-183508, filed on 9/17/2015, the disclosure of which is incorporated herein in its entirety.

Claims

1. A urethane adhesive comprising:

a urethane prepolymer (A) which is a reaction product of one or more polyols (a-1) other than a polyether polyol having one or more ethyleneoxy groups in one molecule, one or more polyether polyols (a-2) having one or more ethyleneoxy groups in one molecule, and one or more polyisocyanates (b); and

a beta-diketone compound (X),

the amount of the β -diketone compound (X) added is 0.1 to 5 parts by mass per 100 parts by mass of the urethane prepolymer (a).

2. The urethane adhesive according to claim 1, wherein at least one of the one or more polyols (a-1) and the one or more polyether polyols (a-2) is a 3-or more-functional polyol having three or more hydroxyl groups.

3. The urethane adhesive according to claim 1 or 2, wherein the number average molecular weight Mn of the polyol (a-1) or the polyether polyol (a-2) is 5,000 or less.

4. The urethane adhesive according to claim 1 or 2, wherein the amount of the one or more polyether polyols (a-2) is 50 parts by mass or more and less than 100 parts by mass relative to 100 parts by mass of the total of the one or more polyols (a-1) and the one or more polyether polyols (a-2).

5. The urethane adhesive according to claim 1 or 2, wherein the one or more polyols (a-1) are one or more polyols selected from the group consisting of polyester polyols having no ethyleneoxy group, polyether polyols having no ethyleneoxy group, polycaprolactone polyols having no ethyleneoxy group, and polycarbonate polyols having no ethyleneoxy group.

6. The urethane adhesive according to claim 1 or 2, further comprising a fatty acid ester (B).

7. The urethane adhesive according to claim 1 or 2, wherein the weight average molecular weight of the urethane prepolymer (a) is 3 to 50 ten thousand.

8. The urethane adhesive according to claim 1 or 2, wherein the polyisocyanate (b) is an aliphatic polyisocyanate.

9. The urethane adhesive according to claim 1 or 2, further comprising an antioxidant.

10. An adhesive sheet comprising an adhesive layer containing a cured product of the urethane adhesive according to claim 1 or 2.

11. A display device comprising an adhesive layer containing a cured product of the urethane adhesive according to claim 1 or 2.