CN116496748A

CN116496748A - Adhesive composition, adhesive layer, adhesive sheet, and adhesive tape

Info

Publication number: CN116496748A
Application number: CN202310061913.3A
Authority: CN
Inventors: 植村由希枝; 唐泽久美子; 纲岛启次
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2022-01-27
Filing date: 2023-01-18
Publication date: 2023-07-28
Also published as: JP2023109343A

Abstract

The present invention relates to an adhesive composition, an adhesive layer, an adhesive sheet and an adhesive tape. Provided is an adhesive composition which can achieve both high biomass and high adhesion. An adhesive composition is used, which is characterized by comprising a urethane resin (A) and a crosslinking agent (B), wherein the urethane resin (A) is the reaction product of a polyol (a 1) and a polyisocyanate (a 2), the polyol (a 1) comprises a linear biomass polyether glycol (a 1-1), and the polyisocyanate (a 2) comprises an aromatic polyisocyanate.

Description

Adhesive composition, adhesive layer, adhesive sheet, and adhesive tape

Technical Field

The present invention relates to an adhesive composition, an adhesive layer, an adhesive sheet and an adhesive tape.

Background

In electronic devices such as mobile electronic terminals, cameras, and computers, and in the manufacturing process thereof, adhesive tapes are used for fixing a protective panel of an image display unit to a case or for fixing various members such as a rigid member such as an exterior member or a battery.

As a raw material used for the pressure-sensitive adhesive tape, an inexpensive acrylic pressure-sensitive adhesive is mainly used, and a petroleum-based raw material is often used. However, recently, there has been an increasing concern about environmental problems such as global warming, and there has been an increasing demand for adhesives using plant-derived raw materials as a substitute for conventional petroleum-derived raw materials.

As such an adhesive, for example, a polyester-based adhesive composition is proposed, which comprises: a polyester polyol obtained by polycondensing a dicarboxylic acid having a side chain with a diol, a polyether polyol, and a crosslinking agent (patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2013-216875

Disclosure of Invention

Problems to be solved by the invention

However, when a plant-derived raw material is used, it is difficult to freely design the primary structure of the polymer contained in the adhesive because the raw material is limited. Therefore, it is difficult to satisfy the conventional performance required by using a plant-derived raw material, and in particular, it is difficult to exert sufficient adhesion when a binder having a high biomass degree is used.

The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an adhesive that can achieve both high biomass and high adhesion.

Solution for solving the problem

The present inventors have found that an adhesive composition containing a specific urethane resin and a crosslinking agent can solve the above-mentioned problems, and have completed the present invention.

Specifically, the present invention relates to an adhesive composition comprising a urethane resin (a) and a crosslinking agent (B), wherein the urethane resin (a) is a reaction product of a polyol (a 1) and a polyisocyanate (a 2), the polyol (a 1) contains a linear biomass polyether diol (a 1-1), and the polyisocyanate (a 2) contains an aromatic polyisocyanate.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an adhesive agent that can achieve both high biomass and high adhesion can be provided.

Detailed Description

The adhesive composition of the present invention comprises a urethane resin (a) and a crosslinking agent (B).

The urethane resin (a) is a reaction product of a polyol (a 1) and a polyisocyanate (a 2).

The polyol (a 1) is a compound having at least 2 hydroxyl groups in 1 molecule, and contains a linear biomass polyether glycol (a 1-1).

Examples of the linear biomass polyether glycol include those obtained by addition polymerization of cyclic ethers using, as an initiator, 1 or 2 or more low-molecular compounds (for example, having a molecular weight of less than 500) each having 2 groups (—nh-or-OH) each having an active hydrogen atom; and those obtained by ring-opening polymerization of a cyclic ether using an acid anhydride as an initiator and transesterification with a low molecular alcohol such as methanol.

Examples of the initiator include compounds having 2 hydroxyl groups such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1, 4-butanediol, 1, 6-hexanediol, bisphenol A, and the like.

Among the above initiators, examples of the biomass-derived compounds include compounds having 2 hydroxyl groups such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1, 4-butanediol, 1, 5-pentanediol, and 1, 6-hexanediol.

The aforementioned biomass-derived ethylene glycol may be produced from bioethanol. The aforementioned biomass-derived 1, 3-propanediol can be produced as follows: glucose is obtained by fermenting and decomposing plants such as corn with anaerobic bacteria, etc., and is dehydrated to form 3-hydroxypropyl aldehyde (HPA) and reduced. Biomass-derived 1, 4-butanediol can be produced as follows: diols are produced from plants, fermented to give succinic acid, which is hydrogenated. The 1, 5-pentanediol and 1, 6-pentanediol can be produced as follows: hemicellulose is obtained from biomass, furfural and pyran formaldehyde are obtained through dehydration reaction of the hemicellulose, and then hydrogenation decomposition is carried out. In addition, polyalkylene glycols and the like can be produced by dehydration, cyclization, polymerization and the like of these compounds.

Examples of the cyclic ether include epoxy compounds such as ethylene oxide and epichlorohydrin; cyclic ethers having 4 or more carbon atoms (preferably 4 to 6 carbon atoms, particularly preferably 4 carbon atoms) such as tetrahydrofuran.

Among the cyclic ethers, as the biomass-derived compound, there may be mentioned an epoxy compound such as ethylene oxide; cyclic ethers such as tetrahydrofuran, and the like. The cyclic ether may be produced by dehydration and cyclization of a low molecular weight polyol.

The linear biomass polyether glycol is preferably not branched in view of easy expression of adhesion. That is, the alkylene group in the oxyalkylene unit is preferably a linear alkylene group and has no substituent such as an alkyl group.

The number of carbon atoms of the oxyalkylene unit contained in the linear biomass polyether glycol is preferably 2 or more, more preferably 3 or more, and still more preferably 4 or less, from the viewpoint of easy compatibility between flexibility and cohesion.

The number average molecular weight of the linear biomass polyether diol (a 1-1) is preferably 500 or more, more preferably 700 or more, still more preferably 900 or more, preferably 10,000 or less, more preferably 5,000 or less, still more preferably 3,000 or less, from the viewpoint of easy compatibility between flexibility and cohesion.

In the present invention, the number average molecular weight (Mn) and the weight average molecular weight (Mw) represent values measured by gel permeation chromatography based on polystyrene conversion.

The content of the linear biomass polyether glycol (a 1-1) is preferably 80 mass% or more, more preferably 85 mass% or more, still more preferably 90 mass% or more, still more preferably 95 mass% or more, and still more preferably 100 mass% or less in the polyol (a 1) from the viewpoint of being capable of exhibiting a higher biomass degree.

The polyol (a 1) preferably contains a polyol (a 1-2) having 3 or more functions in view of the ability to exhibit cohesive force.

Examples of the polyol (a 1-2) having 3 or more functions include polymer polyols such as polyether polyols, polyester polyols, polycarbonate polyols and polybutadiene polyols (preferably polyether polyols); low molecular weight polyols (molecular weight less than 500), and the like.

Examples of the polyether polyol include a compound obtained by addition-polymerizing an alkylene oxide using 1 or 2 or more low-molecular-weight compounds having 3 or more active hydrogen atoms (for example, a compound having a molecular weight of 50 or more and a molecular weight of less than 500) as an initiator; and ring-opening polymerization of a cyclic ether using 1 or 2 or more low-molecular compounds having 3 or more active hydrogen atoms (for example, compounds having a molecular weight of 50 or more and less than 500) as an initiator.

As the compound having 3 or more active hydrogen atoms, 1 or 2 or more kinds may be used, and examples thereof include glycerin, trimethylolethane, and trimethylolpropane.

As the alkylene oxide, 1 or 2 or more kinds may be used, and examples thereof include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, and the like. Examples of the cyclic ether include tetrahydrofuran and alkyl-substituted tetrahydrofuran.

As the aforementioned polyester polyol, it is possible to use: a reaction product obtained by esterifying a low molecular weight polyol with a polycarboxylic acid using 1 or 2 or more low molecular weight compounds having 3 or more active hydrogen atoms (for example, compounds having a molecular weight of 50 or more and less than 500) as an initiator; ring-opening polymers of cyclic ester compounds such as epsilon-caprolactone; the esterification reaction product, a copolymer of a ring-opened polymer, and the like.

Examples of the low molecular weight polyol which can be esterified with the polycarboxylic acid to form a polyester polyol include aliphatic polyols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1, 2-propanediol, 1, 3-propanediol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 5-hexanediol, 1, 6-hexanediol, 2, 5-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 11-undecanediol, 1, 12-dodecanediol, 2-methyl-1, 3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1, 3-propanediol, 3-methyl-1, 5-pentanediol, 2-ethyl-1, 3-hexanediol, 2-methyl-1, 8-octanediol; alicyclic polyols such as 1, 4-cyclohexanedimethanol; hydroquinone, resorcinol; aromatic polyols such as bisphenol a, bisphenol F, and 4,4' -biphenol.

Examples of the polycarboxylic acid include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid, and anhydrides or esters thereof.

Examples of the polycarbonate polyol include a reaction product obtained by reacting a low-molecular polyol with carbonate and/or phosgene using 1 or 2 or more low-molecular compounds having 3 or more active hydrogen atoms (for example, compounds having a molecular weight of 50 or more and less than 500) as an initiator. As the above-mentioned carbonate, 1 or 2 or more kinds may be used, and examples thereof include aliphatic carbonates such as alkyl carbonates (e.g., methyl carbonate, ethyl carbonate, etc.), dialkyl carbonates (e.g., dimethyl carbonate, diethyl carbonate, etc.), and the like; carbonates containing an alicyclic structure such as cyclic carbonates (hereinafter, the term "containing an alicyclic structure" may be abbreviated as "alicyclic"); aromatic carbonates such as diphenyl carbonate.

Examples of the low-molecular polyol capable of reacting with the carbonate and phosgene include the same low-molecular polyol as the low-molecular polyol capable of reacting with the polycarboxylic acid to form a polyester polyol.

The number of functional groups in the polymer polyol is 3 or more, preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less, because the reaction can be controlled relatively easily.

The molecular weight of the polymer polyol is preferably 500 or more, more preferably 700 or more, further preferably 900 or more, preferably 10,000 or less, more preferably 5,000 or less, further preferably 3,000 or less, from the viewpoint of being able to impart cohesive force efficiently.

Examples of the low molecular weight polyol include low molecular weight triols such as trimethylolethane and trimethylolpropane; low molecular weight tetrol such as pentaerythritol; dipentaerythritol and the like.

The number of functional groups of the low molecular weight polyol is 3 or more, preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less, from the viewpoint of relatively easy control of the reaction.

The molecular weight of the low-molecular-weight polyol is preferably less than 500, for example, 50 or more, from the viewpoint of being able to impart cohesive force efficiently.

When the polyol (a 1-2) having 3 or more functions is contained, the content of the polyol (a 1) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 0.8% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 7% by mass or less, because the reaction can be controlled relatively easily.

The polyol (a 1) may contain another polyol (a 1-3) different from the linear biomass polyether polyol (a 1-1) and the polyol (a 1-2) having 3 or more functions.

Examples of the other polyol (a 1-3) include polyether polyols (however, different from the linear biomass polyether polyol (a 1-1) and the polyol (a 1-2) having 3 or more functions), polymer polyols such as polyester diol, polycarbonate diol and polybutadiene diol; a low molecular weight diol; polyols having an acid group, and the like.

Examples of the polyether polyol include a polyether polyol obtained by addition-polymerizing a cyclic ether using, as an initiator, 1 or 2 or more low-molecular compounds (for example, a molecular weight of less than 500) each having at least 2 groups (-NH or-OH) each having an active hydrogen atom; using 1 or 2 or more low molecular compounds (for example, having a molecular weight of less than 500) each having at least 2 groups (-NH or-OH) each having an active hydrogen atom as an initiator, and addition polymerizing an alkylene oxide; and a method comprising ring-opening polymerizing a cyclic ether using an acid anhydride as an initiator and transesterifying the cyclic ether with a low molecular alcohol such as methanol.

Examples of the initiator include compounds having 2 hydroxyl groups such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1, 3-butanediol, 1, 4-butanediol, 1, 6-hexanediol, bisphenol A, and the like.

Examples of the cyclic ether include epoxy compounds such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and epichlorohydrin; cyclic ethers having 4 or more carbon atoms (preferably 4 to 6 carbon atoms, particularly preferably 4 carbon atoms) such as tetrahydrofuran.

As the polyester polyol, a reaction product obtained by esterifying a low molecular weight polyol with a polycarboxylic acid; ring-opening polymers of cyclic ester compounds such as epsilon-caprolactone; the esterification reaction product, a copolymer of a ring-opened polymer, and the like.

Examples of the polycarbonate polyol include a reaction product obtained by reacting a low-molecular polyol with a carbonate and/or phosgene. As the above-mentioned carbonate, 1 or 2 or more kinds may be used, and examples thereof include aliphatic carbonates such as alkyl carbonates (e.g., methyl carbonate, ethyl carbonate, etc.), dialkyl carbonates (e.g., dimethyl carbonate, diethyl carbonate, etc.), and the like; carbonates containing an alicyclic structure such as cyclic carbonates (hereinafter, the term "containing an alicyclic structure" may be abbreviated as "alicyclic"); aromatic carbonates such as diphenyl carbonate.

Examples of the low molecular weight diol include aliphatic polyols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1, 2-propanediol, 1, 3-propanediol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 5-hexanediol, 1, 6-hexanediol, 2, 5-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 11-undecanediol, 1, 12-dodecanediol, 2-methyl-1, 3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1, 3-propanediol, 3-methyl-1, 5-pentanediol, 2-ethyl-1, 3-hexanediol, 2-methyl-1, 8-octanediol; alicyclic polyols such as 1, 4-cyclohexanedimethanol; hydroquinone, resorcinol; aromatic polyols such as bisphenol a, bisphenol F, and 4,4' -biphenol.

As the polyol having an acid group, 1 or 2 or more kinds may be used, and examples thereof include hydroxy acids such as 2, 2-dimethylolpropionic acid, 2-dimethylolbutyric acid, and 2, 2-dimethylolvaleric acid; and a reaction product of the polyhydric alcohol having a carboxyl group and the polycarboxylic acid.

In the case of containing the other polyol, the content of the polyol (a 1) is preferably 20 mass% or less, more preferably 15 mass% or less, still more preferably 10 mass% or less, preferably 0.1 mass% or more, and still more preferably 0.2 mass% or more, in order to maintain a high biomass level.

The content of the polyether polyol (which may be equivalent to any of the linear biomass polyether polyol (a 1-1), the polyol (a 1-2) having 3 or more functions, and the other polyol (a 1-3)) in the polyol (a 1) is preferably 80 mass% or more, more preferably 90 mass% or more, still more preferably 95 mass% or more, and the upper limit is 100 mass% in the polyol (a 1) from the viewpoint of being capable of exhibiting high adhesive force.

The polyisocyanate (a 2) contains an aromatic polyisocyanate.

The aromatic polyisocyanate may be 1 or 2 or more, and examples thereof include diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude (crude) diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, adducts thereof, isocyanurate, biuret, and the like.

The content of the aromatic polyisocyanate is preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 70 mass% or more, and preferably 100 mass% or less in the polyisocyanate (a 2) in view of the capability of expressing cohesive force.

The polyisocyanate (a 2) may contain a polyisocyanate other than the aromatic polyisocyanate, and examples thereof include aliphatic polyisocyanates such as hexamethylene diisocyanate and lysine diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, 4' -dicyclohexylmethane diisocyanate, 2, 4-and/or 2, 6-methylcyclohexane diisocyanate, cyclohexylene (cyclohexylene) diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexylene-1, 2-dicarboxylate, and 2, 5-and/or 2, 6-norbornane diisocyanate, dimer acid diisocyanate, bicycloheptane triisocyanate, hydrogenated xylylene diisocyanate; adducts of aliphatic polyisocyanates or alicyclic polyisocyanates, isocyanurate bodies, biuret bodies, and the like.

The polyisocyanate (a 2) preferably contains a polyisocyanate (a 2-1) having 3 or more functions such as an adduct, an isocyanurate, and a biuret, and the content thereof is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, still more preferably 50% by mass or less, still more preferably 40% by mass or less, and further preferably 30% by mass or less, in view of the capability of expressing cohesive force in the polyisocyanate (a 2).

The molar ratio (NCO/OH) of the isocyanate groups contained in the polyisocyanate (a 2) to the hydroxyl groups contained in the polyol (a 1) (when the chain extender (a 3) described later is contained, the sum of the hydroxyl groups contained in the polyol (a 1) and the active hydrogen atoms contained in the chain extender (a 3)) is 0.5 or more, preferably 0.55 or more, more preferably 0.6 or more, less than 1, and preferably 0.9999 or less, from the viewpoint of the ability to exhibit cohesive force.

The urethane resin (a) may be obtained by reacting the reaction product of the polyol (a 1) and the polyisocyanate (a 2) with a chain extender (a 3).

The chain extender (a 3) may be 1 or 2 or more, and examples thereof include a compound having 2 or more active hydrogen atoms, a polyamine, and the like. Examples of the compound having 2 or more active hydrogen atoms include aliphatic chain extenders such as ethylene glycol, 1, 2-propanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol, 3' -dimethylol heptane, neopentyl glycol, 3-bis (hydroxymethyl) heptane, diethylene glycol, dipropylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, glycerin, and trimethylolpropane; 1, 2-cyclobutanediol, 1, 3-cyclopentanediol, 1, 4-cyclohexanediol, cycloheptanediol, cyclooctanediol, 1, 4-cyclohexanedimethanol, hydroxypropyl cyclohexanol, tricyclo [5.2.1.0 ^2,6 ]Decane-dimethanol, bicyclo [4.3.0]-nonanediol, dicyclohexyl diol, bicyclo [4.3.0]Nonane dimethanol, spiro [3.4 ]]Alicyclic chain extenders such as octanediol, butylcyclohexanediol, 1' -dicyclohexylenediol, cyclohexanediol, hydrogenated bisphenol A, and 1, 3-adamantanediol, and the like, and aliphatic alkylene diols such as ethylene glycol, propylene glycol, 1, 4-butanediol, 1, 6-hexanediol, diethylene glycol, neopentyl glycol, and 1, 3-butanediol are preferable; alicyclic diols such as cyclohexanedimethanol, and the like. Further, examples of the polyamine include polyamine chain extenders such as ethylenediamine, 1, 2-propane diamine, 1, 6-hexamethylenediamine, piperazine, 2, 5-dimethylpiperazine, isophoronediamine, 4 '-dicyclohexylmethane diamine, 3' -dimethyl-4, 4 '-dicyclohexylmethane diamine, 1, 4-cyclohexanediamine, N-hydroxymethylaminoethylamine, N-ethylaminoethylamine, N-methylaminopropylamine, diethylenetriamine, dipropylenetriamine, triethylenetetramine, hydrazine, N' -dimethylhydrazine, 1, 6-hexamethylenedihydrazide, succinic dihydrazide, adipic dihydrazide, glutaric dihydrazide, sebacic dihydrazide, isophthalic dihydrazide, β -semicarbazide propionic acid dihydrazide, 3-semicarbazide-propyl-carbamate, semicarbazide-3-semicarbazide methyl-3, 5-trimethylcyclohexane and the like.

The chain extender (a 3) is preferably 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, and even more preferably 0 to 1 part by mass, based on 100 parts by mass of the polyol (a 1) in view of the ability to exhibit cohesive force.

The urethane resin (a) may be obtained by reacting a reaction product of the polyol (a 1), the polyisocyanate (a 2), and the chain extender (a 3) if necessary with a chain terminator. The isocyanate groups can be deactivated by the use of a chain terminator.

The chain terminator is preferably an alcohol, and examples thereof include 1-functional alcohols such as methanol, ethanol, propanol, and butanol; 2-functional alcohols such as 1, 2-propanediol and 1, 3-butanediol; a polyfunctional polyol; alkanolamines (e.g., ethanolamine, etc.), alkanolamine compounds such as alkanolamine (e.g., diethanolamine, etc.), etc.

Among the polyol (a 1) and the polyisocyanate (a 2), preferred are: (i) the polyol (a 1) contains a polyol (a 1-2) having 3 or more functions, or (ii) the polyisocyanate (a 2) contains a polyisocyanate (a 2-1) having 3 or more functions, or (iii) the polyol (a 1) contains a polyol (a 1-2) having 3 or more functions and the polyisocyanate contains a polyisocyanate (a 2-1) having 3 or more functions, preferably (i) the polyol (a 1) contains a polyol (a 1-2) having 3 or more functions.

The urethane resin (a) is preferably a hydroxyl terminal.

The hydroxyl value of the urethane resin (a) is, for example, 0.1mgKOH/g or more, preferably 0.5mgKOH/g or more, more preferably 1mgKOH/g or more, preferably 40mgKOH/g or less, more preferably 30mgKOH/g or less, and even more preferably 25mgKOH/g or less, in terms of the ability to impart cohesive force by reaction with a crosslinking agent to be added later. The hydroxyl value can be measured according to JIS K0070.

The amount of the urethane bond contained in the urethane resin (a) is preferably 0.8mmol/g or more, more preferably 0.85mmol/g or more, preferably 3mmol/g or less, more preferably 2.5mmol/g or less, and further preferably 2mmol/g or less, from the viewpoint of being capable of exhibiting high adhesion.

The content of the urethane resin (a) is preferably 80 mass% or more, and more preferably 100 mass% or less in terms of the solid content of the adhesive composition, from the viewpoint of high adhesive strength.

The number average molecular weight of the urethane resin (a) is preferably 2,000 or more, more preferably 3,000 or more, still more preferably 4,000 or more, preferably 60,000 or less, more preferably 40,000 or less, still more preferably 20,000 or less, from the viewpoint of being capable of exhibiting a high adhesive force.

The weight average molecular weight of the urethane resin (a) is preferably 10,000 or more, more preferably 15,000 or more, still more preferably 20,000 or more, preferably 300,000 or less, more preferably 250,000 or less, still more preferably 200,000 or less, from the viewpoint of being capable of exhibiting a high adhesive force.

The molecular weight dispersity (Mw/Mn) of the urethane resin (A) is preferably 1.5 or more, more preferably 2 or more, further preferably 2.5 or more, preferably 30 or less, and more preferably 25 or less.

The urethane resin (a) can be produced by reacting the polyol (a 1) with the polyisocyanate (a 2), and if necessary, further reacting the chain extender (a 1-3) and/or the chain terminator. The reaction may be carried out in the presence of an organic solvent, and a urethanization catalyst may be allowed to coexist in the reaction.

As the organic solvent, 1 or 2 or more kinds may be used, and examples thereof include aromatic hydrocarbon solvents such as toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and 3-pentanone; ether solvents such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, and ethyl carbitol; nitrile solvents such as acetonitrile, propionitrile, isobutyronitrile, valeronitrile, etc.; sulfoxide solvents such as dimethyl sulfoxide; amide solvents such as methyl formamide, dimethylacetamide and N-methyl-2-pyrrolidone, and the like.

Examples of the urethane catalyst include nitrogen-containing compounds such as triethylamine, triethylenediamine and N-methylmorpholine, metal salts such as potassium acetate, zinc stearate and tin octoate, and organometallic compounds such as dibutyltin laurate, dioctyltin di-neodecanoate and zirconium tetra-acetylacetonate.

The crosslinking agent (B) may be a compound having 1 molecule with 2 or more groups capable of reacting with hydroxyl groups, and examples thereof include isocyanate crosslinking agents having 1 molecule with 2 or more isocyanate groups; an epoxy crosslinking agent having 2 or more epoxy groups in the molecule 1 and the like are preferable from the viewpoint of being capable of exhibiting high adhesion, and an isocyanate crosslinking agent is preferably contained.

The isocyanate crosslinking agent may be 1 or 2 or more, and examples thereof include polyisocyanates such as toluene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate; trimethylolpropane adducts thereof; their isocyanurate bodies; their biuret forms, and the like. Among these, trimethylolpropane adducts of polyisocyanates and isocyanurate bodies of polyisocyanates are preferably used in view of the ability to exhibit high adhesion.

The content of the isocyanate crosslinking agent is preferably an amount of 0.1 or more, more preferably 0.15 or more, still more preferably 0.2 or more, and preferably 10 or less, more preferably 8 or less, still more preferably 6 or less, in terms of the equivalent ratio of the hydroxyl groups in the urethane resin (a) to the isocyanate groups of the isocyanate crosslinking agent, from the viewpoint of high adhesion.

Examples of the epoxy crosslinking agent that can be used include aliphatic, alicyclic, or aromatic polyol diglycidyl ethers such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, resorcinol diglycidyl ether, phenol (EO) pentaglycidyl ether, bis- (p-hydroxyphenyl) methane diglycidyl ether, 2-bis- (p-hydroxyphenyl) propane diglycidyl ether, tris (p-hydroxyphenyl) methane polyglycidyl ether, and 1, 2-tetrakis (p-hydroxyphenyl) ethane polyglycidyl ether, and lauryl alcohol (EO) pentadecaglycidyl ether; polyglycidyl ethers of aliphatic, alicyclic or aromatic polyhydric alcohol compounds such as glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycidyl ether, pentaerythritol polyglycidyl erythritol and diglycerol polyglycidyl ether; n, N-diglycidyl aniline, N, N-diglycidyl toluidine, 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N, N, N ', polyglycidyl ethers of amine compounds such as N' -tetraglycidyl-m-xylylenediamine and N, N, N ', N' -tetraglycidyl-bis- (p-aminophenyl) methane; diglycidyl terephthalate, diglycidyl isophthalate, diglycidyl naphthalate, polyglycidyl trimellitate, diglycidyl adipate, diglycidyl sebacate, and diglycidyl esters of fatty acids or aromatic acids or polyglycidyl esters; triglycidyl aminophenol; triglycidyl tris (2-hydroxyethyl) isocyanurate, triglycidyl isocyanurate; orthocresol type epoxides, phenol novolac type epoxides, and the like.

The content of the epoxy crosslinking agent is preferably an amount of 1 or more, more preferably 1.2 or more, still more preferably 1.5 or more, still more preferably 5 or less, still more preferably 4 or less, still more preferably 3 or less, in terms of the equivalent ratio of the hydroxyl groups in the urethane resin (a) to the epoxy groups in the epoxy crosslinking agent, from the viewpoint of high adhesion.

The content of the isocyanate crosslinking agent is preferably 80 mass% or more, more preferably 90 mass% or more, still more preferably 95 mass% or more, and 100 mass% or less in the crosslinking agent (B) in view of the capability of exhibiting high adhesion.

The content of the crosslinking agent (B) is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, still more preferably 10 parts by mass or less, and still more preferably 7 parts by mass or less, per 100 parts by mass of the urethane resin (a), in view of the high adhesive strength.

The total content of the urethane resin (a) and the crosslinking agent (B) is preferably 80 mass% or more, more preferably 90 mass% or more, still more preferably 95 mass% or more, and still more preferably 100 mass% or less, based on the solid content of the adhesive composition.

In the present specification, the solid content of the adhesive composition means a portion from which the solvent contained in the adhesive composition is removed.

The foregoing adhesive composition may further comprise a curing catalyst. The curing catalyst may be the same as the compound exemplified as the urethanization catalyst. When the curing catalyst is contained, the content thereof is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, still more preferably 0.01 parts by mass or more, preferably 1 part by mass or less, more preferably 0.1 parts by mass or less, still more preferably 0.05 parts by mass or less, based on 100 parts by mass of the urethane resin (a).

The foregoing adhesive composition may further comprise a solvent. The solvent may be the same as the organic solvent exemplified above. When the organic solvent is contained, the content thereof in the adhesive composition is preferably 20 mass% or more, more preferably 30 mass% or more, and preferably 80 mass% or less, more preferably 70 mass% or less.

The aforementioned adhesive composition may further contain, as other additives, plasticizers, silane coupling agents, antioxidants, light stabilizers, rust inhibitors, thixotropic imparting agents, sensitizers, polymerization inhibitors, leveling agents, tackifiers, antistatic agents, flame retardants, and the like.

The biomass content of the solid component of the adhesive composition is preferably 50% by mass or more, more preferably 60% by mass or more, for example 98% by mass or less, preferably 95% by mass or less, more preferably 92% by mass or less.

The biomass degree can be calculated by dividing the total amount of the biomass-derived components in the raw materials used for producing the binder composition by the total amount of the raw materials.

The adhesive composition is applied to a substrate, and the solvent is removed if necessary, and further aged if necessary, whereby an adhesive layer which is a cured product of the adhesive composition can be formed. The thickness of the adhesive layer is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less.

Examples of the method for forming a sheet from the adhesive composition include a method of applying the adhesive composition to a plastic substrate and drying and curing the adhesive composition.

As the plastic base material, for example, polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate can be used; polyolefin resins such as polyethylene and polypropylene; a polyacrylic resin; polyvinyl chloride resin; a polypropylene ethylene vinyl alcohol; a polyvinyl alcohol resin; a polyurethane resin; a polyamide resin; a sheet or film obtained from polyimide resin, etc. The surface of these plastic substrates may be subjected to a mold release treatment, an antistatic treatment, a corona treatment, or the like. The thickness of the plastic base material is, for example, in the range of 10 to 200. Mu.m.

Examples of the method for coating the adhesive composition on the plastic substrate include coating methods using a roll coater, a gravure coater, a reverse coater, a spray coater, an air knife coater, a die coater, and the like.

The degree of biomass of the adhesive layer is preferably 50 mass% or more, more preferably 60 mass% or more, for example 98 mass% or less, preferably 95 mass% or less, more preferably 92 mass% or less.

The adhesive layer as a cured product of the adhesive composition is useful as an adhesive tape for fixing a protective panel of an image display section to a case, fixing a rigid member such as an exterior member or a battery, or the like in a manufacturing process of electronic equipment such as a mobile electronic terminal, a camera, or a computer, and the like, while achieving both high biomass and high adhesive strength.

Examples (example)

Hereinafter, the present invention will be described more specifically with reference to examples.

The number average molecular weight and the weight average molecular weight of the urethane resin were measured by the following GPC measurement method.

GPC measurement method

Measurement device: high performance GPC apparatus (HLC-8220 GPC manufactured by Tosoh Co., ltd.)

Column: the columns described below, manufactured by Tosoh corporation, were used in series.

(1) TSK-GEL HXL-H (protective column)

(2)TSK-GEL GMHXL

(3)TSK-GEL GMHXL

(4)TSK-GEL GMHXL

(5)TSK-GEL GMHXL

Sample concentration: dilution with tetrahydrofuran was performed to bring to 4mg/mL mobile phase solvent: tetrahydrofuran (THF)

Flow rate: 1.0mL/min

Injection amount: 100 mu L

Column temperature: 40 DEG C

Standard sample: standard curves were made using standard polystyrene as described below.

(Standard polystyrene)

TSKgel Standard polystyrene A-500 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene A-1000 manufactured by Tosoh Co., ltd. "TSKgel Standard polystyrene A-2500 manufactured by Tosoh Co., ltd." TSKgel Standard polystyrene A-5000 manufactured by Tosoh Co., ltd. "TSKgel Standard polystyrene F-1 manufactured by Tosoh Co., ltd.)"

TSKgel Standard polystyrene F-2 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-4 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-10 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-20 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-40 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-80 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-128 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-288 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-550 manufactured by Tosoh Co., ltd "

TSKgel Standard polystyrene F-850 manufactured by Tosoh Co., ltd "

Example 1

847 parts by mass of biomass poly (1, 3-propylene glycol) ("PPD-1") as a linear biomass polyether polyol (a 1-1), 20 parts by mass of polypropylene glycol glycerol ether ("UNOL TG-330", manufactured by Nikko Co., ltd., number average molecular weight: 330) as a 3-functional polyol (a 1-2), 133 parts by mass of Toluene Diisocyanate (TDI) as a polyisocyanate (a 2), and 428 parts by mass of Methyl Ethyl Ketone (MEK) were added to a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet pipe, and a thermometer. After the temperature in the reaction vessel was raised to 40 ℃, 0.2 parts by mass of tin octoate ("NEOSTANN U-28", manufactured by Nito chemical Co., ltd.) was added thereto, and the temperature was raised to 75℃over 1 hour. Thereafter, the reaction was stopped with 1.1 parts by mass of 1, 3-butanediol (1, 3-BG) after confirming the disappearance of all isocyanate groups by holding at 75℃for 12 hours, and 571 parts by mass of MEK was added to obtain a MEK solution (solid content: 50% by mass) of the urethane resin (A-1). The weight average molecular weight of the obtained urethane resin (A-1) was 14,200.

To 100 parts by mass of the urethane resin (A-1), an isocyanurate body (TKA-100) of hexamethylene diisocyanate as an isocyanate curing agent and dioctyltin di-neodecanoate as a curing catalyst were blended to obtain an adhesive composition (1). The PET film having a thickness of 50 μm, which was coated on the surface and subjected to the mold release treatment, was dried at 80℃for 3 minutes. The PET film having the release-treated surface was bonded thereto, and cured at 40℃for 48 hours to give a base-material-free adhesive sheet (1) having a thickness of 50. Mu.m.

[ method for evaluating adhesion ]

The adhesive sheet (1) without a base material obtained in the above was cut into test pieces having a width of 20 mm. The release film was peeled off from the test piece and attached to the SUS plate by 1 round trip with a 2kg roller so that the adhesion area became 20mm×60 mm. After 1 hour of adhesion, 180-degree peel test was performed at 23℃under a 50% humidity atmosphere to obtain an adhesive strength (N/20 mm). The adhesion was evaluated according to the following criteria.

O: 4.0 or more

Delta: 2.0 or more and less than 4.0

X: 2.0 or less

Examples 2 to 10 and comparative examples 1 to 3

A MEK solution (solid content 50 mass%) of urethane resins (a-2) to (a-12) was obtained in the same manner as in example 1, except that the linear biomass polyether polyol (a 1-1), the 3-functional polyol (a 1-2), the other polyol (a 1-3) and the polyisocyanate (a 2) used in example 1 were changed to the compounds shown in table 1. Further, adhesive force was evaluated by obtaining adhesive compositions (2) to (10) and (R1) to (R3) and then obtaining adhesive sheets without substrates, respectively, in the same manner as in example 1, except that the compounds shown in table 1 were used for the crosslinking agent (B).

The compositions and evaluation results of the adhesive compositions (1) to (10) and (R1) to (R3) obtained in the above are shown in tables 1 to 4.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

In the tables, the abbreviations respectively represent the following compounds.

"PPD-1": biomass poly (1, 3-propanediol) (number average molecular weight; 1000, hydroxyl number; 105.2 mgKOH/g)

"PPD-2": biomass poly (1, 3-propanediol) (number average molecular weight; 2000, hydroxyl number; 55.1 mgKOH/g)

"PTG-1": biomass polytetramethylene ether glycol (number average molecular weight; 1000, hydroxyl number; 112.5 mgKOH/g)

"TG-330": polypropylene glycol Glycerol ether ("UNICOL TG-330", manufactured by Nitro Corp., number average molecular weight; 330, hydroxyl value; 502 mgKOH/g)

"G-750": polyoxyethylene glyceryl ether ("UNIX G-750", manufactured by Nitro Kabushiki Kaisha, number average molecular weight; 750, hydroxyl value; 224 mgKOH/G)

"GL-3000": polyoxyethylene polyoxypropylene triol "SANNIX GL-3000", number average molecular weight, made by Sanyo chemical industry Co., ltd; 3000. hydroxyl number; 54.4 mgKOH/g)

"TMP": trimethylolpropane

"14BG":1, 4-butanediol

"HDI": hexamethylene diisocyanate

"TDI": toluene diisocyanate

"MDI":4,4' -diphenylmethane diisocyanate

"T1890/100": isocyanurates having 3 or more isocyanate groups of isophorone diisocyanate ("VESTANAT T1890/100", manufactured by Evonik Co., ltd.; NCO%; 17.1% by mass)

"24A-100": biuret having 3 isocyanate groups of hexamethylene diisocyanate ("Duranate 24A-100", manufactured by Asahi Kasei Co., ltd.; NCO%; 23.5% by mass)

"TUL-100": isocyanurate having 3 isocyanate groups of hexamethylene diisocyanate ("Duranate TUL-100", NCO; 23.0% by mass) manufactured by Asahi Kasei Co., ltd

"TKA-100": isocyanurate of hexamethylene diisocyanate ("Duranate TKA-100", manufactured by Asahi Kasei Co., ltd.; NCO%; 21.7% by mass)

"L-55E": trimethylolpropane adduct of toluene diisocyanate ("CORONATE L-55E", manufactured by Tosoh Co., ltd.; NCO%; 9.6% by mass)

As is clear from examples 1 to 10, the adhesive composition of the present invention can achieve both high biomass and high adhesion.

On the other hand, comparative examples 1 to 3 are examples in which the polyisocyanate (a 2) does not contain an aromatic polyisocyanate, and the adhesion is poor.

Claims

1. An adhesive composition comprising a urethane resin (A) and a crosslinking agent (B),

the urethane resin (A) is a reaction product of a polyol (a 1) and a polyisocyanate (a 2),

the polyol (a 1) contains a linear biomass polyether glycol (a 1-1),

the polyisocyanate (a 2) comprises an aromatic polyisocyanate.

2. The adhesive composition according to claim 1, which has a biomass of 50% or more.

3. The adhesive composition according to claim 1 or 2, wherein the urethane bond amount of the urethane resin (a) is 0.6 to 3mmol/g.

4. The adhesive composition according to any one of claims 1 to 3, wherein the polyol (a 1) comprises a polyol (a 1-2) having 3 or more functions, or the polyisocyanate (a 2) comprises a polyisocyanate (a 2-1) having 3 or more functions.

5. The adhesive composition according to any one of claims 1 to 4, wherein the crosslinking agent (B) comprises an isocyanate crosslinking agent (B1) having 2 or more isocyanate groups in 1 molecule.

6. An adhesive layer formed from the adhesive composition of any one of claims 1-5.

7. An adhesive sheet having the adhesive layer according to claim 6.

8. An adhesive tape having the adhesive layer of claim 6.