Polyurethane adhesive composition and polyurethane adhesive

Abstract

To provide a polyurethane adhesive composition for creating a polyurethane adhesive that excels in stable adhesion, and to provide a polyurethane adhesive that excels in stable adhesion.SOLUTION: A polyurethane adhesive composition contains a polyol component (A) and a polyisocyanate component (B). The polyisocyanate component (B) contains a derivative of xylylene diisocyanate.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyurethane adhesive composition and a polyurethane adhesive.

Background Art

[0002] A polyurethane adhesive is a cured resin having adhesiveness. Polyurethane adhesives are used, for example, in the fields of information equipment, housing, building materials, automobiles, railways, daily life, and healthcare.

[0003] A polyurethane adhesive is formed by reacting and curing a polyurethane adhesive composition (an uncured resin composition). The polyurethane adhesive composition contains, for example, a polyol component and a polyisocyanate component.

[0004] As the polyurethane adhesive composition, for example, the following adhesive composition (an uncured resin composition) has been proposed. This adhesive composition is applied to a substrate and dried to form an adhesive layer (a cured resin). The adhesive composition contains a polyurethane polyol (A), an isocyanate curing agent (B), a plasticizer (C), an antioxidant, an antistatic agent, a polyfunctional polyol, and a solvent. The polyurethane polyol contains a reaction product of a polyol (a) and a polyisocyanate (b). The polyol (a) contains a polyester polyol having a number average molecular weight of 1000 and a polyether polyol having a number average molecular weight of 1000. The polyisocyanate (b) contains hexamethylene diisocyanate. The isocyanate curing agent contains a trimethylolpropane adduct of hexamethylene diisocyanate (see, for example, Patent Document 1 (Examples 21 and Synthesis Example 3)). <000001​​​​​​​​​​​​ [Overview of the project] [Problems that the invention aims to solve]

[0006] On the other hand, the above-mentioned isocyanate curing agent contains a trimethylolpropane adduct of hexamethylene diisocyanate. Therefore, the adhesive layer obtained using the above-mentioned isocyanate curing agent has the drawback of being prone to changes in adhesive strength. Thus, there is a need to improve the adhesive strength stability of the adhesive layer.

[0007] The present invention relates to a polyurethane adhesive composition for obtaining a polyurethane adhesive having excellent adhesive stability, and to a polyurethane adhesive having excellent adhesive stability. [Means for solving the problem]

[0008] The present invention [1] is a polyurethane adhesive composition containing a polyol component (A) and a polyisocyanate component (B), wherein the polyisocyanate component (B) contains a derivative of xylylene diisocyanate.

[0009] The present invention [2] includes the polyurethane adhesive composition described in [1] above, wherein the derivative of xylylene diisocyanate contains at least one selected from the group consisting of a polyol adduct of xylylene diisocyanate, an allophanate modified product of xylylene diisocyanate, and an isocyanurate modified product of xylylene diisocyanate.

[0010] The present invention [3] includes a polyurethane adhesive composition according to [1] or [2] above, wherein the equivalent ratio (NCO / OH) of the isocyanate groups of the polyisocyanate component (B) to the hydroxyl groups of the polyol component (A) is 0.05 or more and less than 1.0.

[0011] The present invention [4] includes a polyurethane adhesive composition according to any one of the above [1] to [3], wherein the polyol component (A) contains a polyurethane polyol (a).

[0012] The present invention [5] includes a polyurethane adhesive formed from a polyurethane adhesive composition described in any one of the above [1] to [4]. [Effects of the Invention]

[0013] The polyurethane adhesive composition of the present invention contains a polyisocyanate component (B) which is a derivative of xylylene diisocyanate. Therefore, according to the above polyurethane adhesive composition, a polyurethane adhesive with excellent adhesive stability can be obtained.

[0014] The polyurethane adhesive of the present invention is formed from the above-described polyurethane adhesive composition. Therefore, the above-described polyurethane adhesive has excellent adhesive stability. [Modes for carrying out the invention]

[0015] 1. Polyurethane adhesive composition The polyurethane adhesive composition of the present invention is an uncured resin composition. The polyurethane adhesive composition contains a polyol component (A) and a polyisocyanate component (B).

[0016] More specifically, the polyurethane adhesive composition is, for example, a two-component curable polyurethane adhesive composition. The two-component curable polyurethane adhesive composition comprises a polyol component (A) as the main component and a polyisocyanate component (B) as the curing agent, in separate packages. The main component (polyol component (A)) and the curing agent (polyisocyanate component (B)) are blended together when the two-component curable polyurethane adhesive composition is used, as will be described later.

[0017] (1) Polyol component (A) The polyol component (A) contains, for example, a macropolyol (A1). Preferably, the polyol component (A) consists of a macropolyol (A1).

[0018] Macropolyols (A1) are relatively high molecular weight organic compounds having two or more hydroxyl groups in their molecules. The number-average molecular weight of macropolyols (A1) is, for example, greater than 400 and less than or equal to 20,000. The number-average molecular weight can be calculated from the hydroxyl group equivalent and the average number of hydroxyl groups using known methods. The number-average molecular weight can also be measured as polystyrene-equivalent molecular weight by gel permeation chromatography (the same applies hereafter).

[0019] The macropolyol (A1) is not particularly limited and includes known macropolyols. More specifically, macropolyols (A1) include, for example, polyether polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols. These can be used individually or in combination of two or more.

[0020] Macropolyol (A1) preferably contains polyurethane polyol. That is, polyol component (A) preferably contains polyurethane polyol. Hereinafter, polyurethane polyol will be denoted by the symbol (a).

[0021] Polyurethane polyol (a) is a reaction product of raw material polyol (a1) and raw material polyisocyanate (a2), and has hydroxyl groups at the molecular ends.

[0022] The raw material polyol (a1) is not particularly limited, and examples thereof include the above-mentioned macro polyol. Preferably, the raw material polyol (a1) includes polyether polyol, polyester polyol, and polycarbonate polyol. More preferably, the raw material polyol (a1) includes polyether polyol and polyester polyol.

[0023] Particularly preferably, the raw material polyol (a1) is a combination of polyether polyol and polyester polyol. Hereinafter, the polyether polyol is denoted by the symbol (a1-1). Also, hereinafter, the polyester polyol is denoted by the symbol (a1-2).

[0024] Examples of the polyether polyol (a1-1) include polyoxyalkylene (having carbon atoms of 2 to 3) polyol and polyoxytetramethylene ether polyol.

[0025] Examples of the polyoxyalkylene (having carbon atoms of 2 to 3) polyol include polyoxyethylene polyol, polyoxypropylene polyol, polyoxytriethylene polyol, and polyoxyethylene·polyoxypropylene polyol (random or block copolymer).

[0026] Examples of the polytetramethylene ether polyol include a ring-opening polymer obtained by cationic polymerization of tetrahydrofuran (crystalline polytetramethylene ether glycol). Also, examples of the polytetramethylene ether polyol include amorphous polytetramethylene ether glycol. The amorphous polytetramethylene ether glycol is obtained by copolymerization of tetrahydrofuran with alkyl-substituted tetrahydrofuran and / or a dihydric alcohol. Note that the crystalline property indicates the property of being solid at 25°C. Also, the amorphous property indicates the property of being liquid at 25°C.

[0027] Polyether polyol (a1-1) can be used alone or in combination of two or more types. Preferably, polyoxyalkylene (2-3 carbon atoms) polyols are used as polyether polyol (a1-1), and more preferably, polyoxypropylene polyols are used.

[0028] The number-average molecular weight of polyether polyol (a1-1) is not particularly limited and is set appropriately according to the purpose and application. The number-average molecular weight of polyether polyol (a1-1) is, for example, greater than 400, preferably 500 or more. Alternatively, the number-average molecular weight of polyether polyol (a1-1) is, for example, 5000 or less, preferably 4000 or less.

[0029] The number-average molecular weight of the polyether polyol (a1-1) is preferably higher than that of the polyester polyol (a1-2) described later. More specifically, from the viewpoint of water resistance, the number-average molecular weight of the polyether polyol (a1-1) is preferably 1000 or more, more preferably 1500 or more, even more preferably 2000 or more, and particularly preferably 2500 or more. Furthermore, from the viewpoint of stain resistance and heat and humidity resistance, the number-average molecular weight of the polyether polyol (a1-1) is preferably 3500 or less, preferably 3200 or less, more preferably 3000 or less, and even more preferably 2900 or less.

[0030] The average number of hydroxyl groups in polyether polyol (a1-1) is, for example, 2 or more, preferably 2.5 or more. Alternatively, the average number of hydroxyl groups in polyether polyol (a1-1) is, for example, 6 or less, preferably 4 or less.

[0031] The average number of hydroxyl groups of the polyether polyol (a1-1) is preferably higher than that of the polyester polyol (a1-2) described later. More specifically, the average number of hydroxyl groups of the polyether polyol (a1-1) is particularly preferably 3 from the viewpoint of stain resistance, water resistance and heat and humidity resistance.

[0032] Furthermore, when two or more types of polyether polyols (a1-1) are used in combination, the number-average molecular weight and average number of hydroxyl groups of the polyether polyol (a1-1) are the same as the number-average molecular weight and average number of hydroxyl groups of the mixture of the two or more types of polyether polyols (a1-1).

[0033] The content of polyether polyol (a1-1) is adjusted, for example, based on the number of hydroxyl groups. More specifically, the proportion of hydroxyl groups derived from polyether polyol (a1-1) relative to the total moles of hydroxyl groups derived from polyether polyol (a1-1) and polyester polyol (a1-2) is, for example, 30 mol% or more, preferably 40 mol% or more, and more preferably 50 mol% or more. Also, the proportion of hydroxyl groups derived from polyether polyol (a1-1) relative to the total moles of hydroxyl groups derived from polyether polyol (a1-1) and polyester polyol (a1-2) is, for example, 80 mol% or less, preferably 70 mol% or less, and more preferably 60 mol% or less.

[0034] Examples of polyester polyols (a1-2) include condensed polyester polyols and ring-opening polyester polyols. Examples of condensed polyester polyols include condensates of low molecular weight polyols and polybasic acids. Examples of ring-opening polyester polyols include ring-opening polymers of lactones and / or lactides. Preferably, polyester polyols (a1-2) are condensed polyester polyols.

[0035] In other words, the polyester polyol (a1-2) preferably contains a condensate of a low molecular weight polyol and a polybasic acid.

[0036] Low molecular weight polyols are organic compounds with two or more hydroxyl groups in their molecule and a relatively low molecular weight. The molecular weight of low molecular weight polyols is, for example, 40 or more and less than 400, preferably 300 or less. Examples of low molecular weight polyols include dihydric alcohols, trihydric alcohols, and tetrahydric or higher alcohols. Examples of dihydric alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and dipropylene glycol. Examples of trihydric alcohols include glycerin and trimethylolpropane. Examples of tetrahydric or higher alcohols include pentaerythritol and diglycerin. These can be used individually or in combination of two or more types.

[0037] As low molecular weight polyols, dihydric alcohols are preferred. As dihydric alcohols, branched dihydric alcohols are preferred. Among the above dihydric alcohols, examples of branched dihydric alcohols include neopentyl glycol and 3-methyl-1,5-pentanediol. As low molecular weight polyols, neopentyl glycol is particularly preferred from the viewpoint of stain resistance, water resistance and heat and humidity resistance.

[0038] Examples of polybasic acids include saturated aliphatic dicarboxylic acids, unsaturated aliphatic dicarboxylic acids, aromatic dicarboxylic acids, alicyclic dicarboxylic acids, other carboxylic acids, acid anhydrides, and acid halides. Examples of saturated aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, 1,1-dimethyl-1,3-dicarboxypropane, 3-methyl-3-ethylglutaric acid, azelaic acid, and sebacic acid. Examples of unsaturated aliphatic dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Examples of aromatic dicarboxylic acids include orthophthalic acid, isophthalic acid, terephthalic acid, toluenedicarboxylic acid, and naphthalenedicarboxylic acid. Examples of alicyclic dicarboxylic acids include hexahydrophthalic acid. Examples of other carboxylic acids include dimer acids, hydrogenated dimer acids, and hetic acid. Examples of acid anhydrides include oxalic acid anhydride, succinic acid anhydride, maleic acid anhydride, phthalic acid anhydride, alkyl succinic acid anhydride, tetrahydrophthalic acid anhydride, and trimellitic acid anhydride. Examples of acid halides include oxalic acid dichloride, adipic acid dichloride, and sebacate acid dichloride. These can be used individually or in combination of two or more types.

[0039] The method for condensing a low molecular weight polyol with a polybasic acid is not particularly limited. For example, the low molecular weight polyol and the polybasic acid can be esterified in appropriate proportions. In the esterification, a known esterification catalyst can be used as needed. This produces a condensed polyester polyol. Alternatively, the condensed polyester polyol can also be produced, for example, by a transesterification reaction between the alkyl ester of the polybasic acid described above and the low molecular weight polyol described above.

[0040] Polyester polyols (a1-2) can be used alone or in combination of two or more types. Preferably, polyester polyols (a1-2) are condensed polyester polyols, and more preferably, condensates of a low molecular weight polyol containing neopentyl glycol and a polybasic acid.

[0041] The number-average molecular weight of polyester polyol (a1-2) is not particularly limited and is set appropriately according to the purpose and application. The number-average molecular weight of polyester polyol (a1-2) is, for example, greater than 400, preferably 500 or more. Alternatively, the number-average molecular weight of polyester polyol (a1-2) is, for example, 5000 or less, preferably 4000 or less.

[0042] The number-average molecular weight of the polyester polyol (a1-2) is preferably lower than that of the polyether polyol (a1-1) described above. More specifically, from the viewpoint of stain resistance, the number-average molecular weight of the polyester polyol (a1-2) is less than 1000, preferably 950 or less, more preferably 900 or less, and even more preferably 850 or less. Furthermore, from the viewpoint of water resistance and heat and humidity resistance, the number-average molecular weight of the polyester polyol (a1-2) is 500 or more, preferably 600 or more, and more preferably 700 or more.

[0043] The average number of hydroxyl groups in polyester polyol (a1-2) is, for example, 2 or more. Alternatively, the average number of hydroxyl groups in polyester polyol (a1-2) is, for example, 6 or less, preferably 4 or less.

[0044] The average number of hydroxyl groups of the polyester polyol (a1-2) is preferably lower than the average number of hydroxyl groups of the polyether polyol (a1-1) described above. More specifically, the average number of hydroxyl groups of the polyester polyol (a1-2) is more preferably 3 or less, even more preferably 2.5 or less, and particularly preferably 2, from the viewpoint of stain resistance, water resistance and heat and humidity resistance.

[0045] Furthermore, when two or more types of polyester polyols (a1-2) are used in combination, the number-average molecular weight and average number of hydroxyl groups of the polyester polyol (a1-2) are the same as the number-average molecular weight and average number of hydroxyl groups of the mixture of the two or more types of polyester polyols (a1-2).

[0046] The content of polyester polyol (a1-2) is adjusted, for example, based on the number of hydroxyl groups. More specifically, the proportion of hydroxyl groups derived from polyester polyol (a1-2) relative to the total moles of hydroxyl groups derived from polyether polyol (a1-1) and polyester polyol (a1-2) is, for example, 20 mol% or more, preferably 30 mol% or more, and more preferably 40 mol% or more. Also, the proportion of hydroxyl groups derived from polyester polyol (a1-2) relative to the total moles of hydroxyl groups derived from polyether polyol (a1-1) and polyester polyol (a1-2) is, for example, 70 mol% or less, preferably 60 mol% or less, and more preferably 50 mol% or less.

[0047] Furthermore, the content of hydroxyl groups derived from polyester polyol (a1-2) is, for example, 50 moles or more, preferably 60 moles or more, per 100 moles of hydroxyl groups derived from polyether polyol (a1-1). Also, the content of hydroxyl groups derived from polyester polyol (a1-2) is, for example, 100 moles or less, preferably 90 moles or less, per 100 moles of hydroxyl groups derived from polyether polyol (a1-1).

[0048] The raw material polyol (a1) may contain other raw material polyols. The other raw material polyols are polyols other than the polyether polyol (a1-1) and polyester polyol (a1-2) described above.

[0049] Other raw material polyols include, for example, the low molecular weight polyols mentioned above, and known macropolyols (excluding polyether polyols and polyester polyols).

[0050] From the viewpoint of stain resistance, water resistance, and heat and humidity resistance, the content of other raw material polyols is, for example, less than 50% by mass, preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 0% by mass, relative to the total amount of raw material polyol (a1).

[0051] In other words, the raw material polyol (a1) preferably does not contain any other raw material polyols and consists of the above-mentioned polyether polyol (a1-1) and the above-mentioned polyester polyol (a1-2).

[0052] Examples of the raw material polyisocyanate (a2) include polyisocyanate monomers and polyisocyanate derivatives.

[0053] Examples of polyisocyanate monomers include aliphatic polyisocyanates, aromatic polyisocyanates, and aromatic aliphatic polyisocyanates. These polyisocyanate monomers can be used individually or in combination of two or more types.

[0054] Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 1,2-propane diisocyanate, 1,2-butane diisocyanate, 2,3-butane diisocyanate, 1,3-butane diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate. These can be used individually or in combination of two or more.

[0055] Furthermore, aliphatic polyisocyanates also include alicyclic polyisocyanates. Examples of alicyclic polyisocyanates include isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), and methylenebis(cyclohexyl isocyanate) (H 12 Examples include MDI and bis(isocyanatomethyl)cyclohexane (H6XDI). These can be used alone or in combination of two or more.

[0056] Examples of aromatic polyisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), toluidine diisocyanate (TODI), paraphenylenedi diisocyanate, and naphthalene diisocyanate (NDI). These can be used individually or in combination of two or more types.

[0057] Examples of aromatic aliphatic polyisocyanates include xylylene diisocyanate (XDI) and tetramethyl xylylene diisocyanate (TMXDI). These can be used individually or in combination of two or more types.

[0058] Examples of polyisocyanate derivatives include modified products obtained by modifying the above-mentioned polyisocyanate monomers using known methods. Examples of polyisocyanate derivatives include polymers, isocyanurate modified products, allophanate modified products, polyol adducts, biuret modified products, urea modified products, oxadiazinetrione modified products, and carbodiimide modified products. Polymethylene polyphenylene polyisocyanate is also an example of a polyisocyanate derivative. These polyisocyanate derivatives can be used individually or in combination of two or more types.

[0059] Preferably, the raw material polyisocyanate (a2) is a polyisocyanate monomer, more preferably an aliphatic polyisocyanate monomer, and even more preferably hexamethylene diisocyanate and pentamethylene diisocyanate. From the viewpoint of stain resistance, water resistance and heat and humidity resistance, pentamethylene diisocyanate is particularly preferred. Furthermore, from the viewpoint of availability and low cost, hexamethylene diisocyanate is particularly preferred.

[0060] Polyurethane polyol (a) is obtained by reacting raw material polyol (a1) with raw material polyisocyanate (a2) in the following manner.

[0061] More specifically, to obtain polyurethane polyol (a), for example, a urethane reaction is carried out between raw material polyol (a1) and raw material polyisocyanate (a2) under an inert gas atmosphere.

[0062] In the urethane formation reaction, the equivalent ratio (NCO / OH) of the isocyanate groups of the raw material polyisocyanate (a2) to the hydroxyl groups of the raw material polyol (a1) is, for example, 0.5 or more, preferably 0.6 or more. Also, the equivalent ratio (NCO / OH) of the isocyanate groups of the raw material polyisocyanate (a2) to the hydroxyl groups of the raw material polyol (a1) is, for example, less than 1.0, preferably 0.9 or less.

[0063] In the urethane reaction, known urethane catalysts are added as needed. Examples of urethane catalysts include amines, organometallic compounds, and potassium salts. These are used individually or in combination of two or more. The proportion of urethane catalysts added is set appropriately according to the purpose and application.

[0064] The reaction conditions for the urethane formation reaction are not particularly limited. For example, the reaction temperature may be between 40°C and 100°C. The reaction time may be between 2 hours and 24 hours. As a result, polyurethane polyol (a) is obtained as the reaction product of raw material polyol (a1) and raw material polyisocyanate (a2).

[0065] The number-average molecular weight of polyurethane polyol (a) is, for example, greater than 400, preferably 500 or more, more preferably 1000 or more, and even more preferably 1500 or more. Alternatively, the number-average molecular weight of polyurethane polyol (a) is, for example, 20000 or less, preferably 15000 or less, more preferably 10000 or less, and even more preferably 5000 or less.

[0066] The average number of hydroxyl groups in polyurethane polyol (a) is, for example, 2 or more, preferably more than 2, and more preferably 2.1 or more. Alternatively, the average number of hydroxyl groups in polyurethane polyol (a) is, for example, 4 or less, preferably 3 or less, more preferably less than 3, and even more preferably 2.8 or less.

[0067] The number-average molecular weight of macropolyol (A1) is, for example, greater than 400, preferably 500 or more, more preferably 1000 or more, and even more preferably 1500 or more. Alternatively, the number-average molecular weight of macropolyol (A1) may be 20000 or less, preferably 15000 or less, more preferably 10000 or less, and even more preferably 5000 or less.

[0068] The average number of hydroxyl groups in macropolyol (A1) is, for example, 2 or more, preferably more than 2, and more preferably 2.1 or more. Alternatively, the average number of hydroxyl groups in macropolyol (A1) is, for example, 4 or less, preferably 3 or less, more preferably less than 3, and even more preferably 2.8 or less.

[0069] The polyol component (A) may, if necessary, contain a low molecular weight polyol (A2) in addition to the macropolyol (A1) described above. Examples of low molecular weight polyols (A2) include the dihydric alcohol, trihydric alcohol, and tetrahydric alcohol described above. These can be used individually or in combination of two or more types.

[0070] Preferably, the polyol component (A) does not contain a low molecular weight polyol (A2). That is, the polyol component (A) preferably consists of a macropolyol (A1), and more preferably consists of the polyurethane polyol (a) described above.

[0071] The number-average molecular weight of polyol component (A) is, for example, greater than 400, preferably 500 or more, more preferably 1000 or more, and even more preferably 1500 or more. Alternatively, the number-average molecular weight of polyol component (A) may be 20000 or less, preferably 15000 or less, more preferably 10000 or less, and even more preferably 5000 or less.

[0072] The average number of hydroxyl groups of polyol component (A) is, for example, 2 or more, preferably more than 2, and more preferably 2.1 or more. Alternatively, the average number of hydroxyl groups of polyol component (A) is, for example, 4 or less, preferably 3 or less, more preferably less than 3, and even more preferably 2.8 or less.

[0073] The polyol component (A) may be dissolved and / or dispersed in an organic solvent. That is, the polyol component (A) may be prepared as a solution and / or dispersion. In other words, the main component of the two-component curable polyurethane adhesive composition may be a solution and / or dispersion of the polyol component (A) in an organic solvent.

[0074] Examples of organic solvents include ketones, nitriles, alkyl esters, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ethers, glycol ether esters, halogenated aliphatic hydrocarbons, and polar aprotons. These can be used individually or in combination of two or more. The mixing ratio of the organic solvents is set appropriately according to the purpose and application.

[0075] In the organic solvent solution and / or dispersion of polyol component (A), the solid content concentration of polyol component (A) is, for example, 30% by mass or more, preferably 40% by mass or more. Alternatively, in the organic solvent solution and / or dispersion of polyol component (A), the solid content concentration of polyol component (A) is, for example, less than 100% by mass, preferably 90% by mass or less.

[0076] (2) Polyisocyanate component (B) Polyisocyanate component (B) contains a derivative of xylylene diisocyanate.

[0077] Derivatives of xylylene diisocyanate are modified products obtained by modifying xylylene diisocyanate (monomer).

[0078] Examples of xylylene diisocyanates (monomers) include 1,2-xylylene diisocyanate (o-XDI), 1,3-xylylene diisocyanate (m-XDI), and 1,4-xylylene diisocyanate (p-XDI). These can be used individually or in combination of two or more types. Preferably, the xylylene diisocyanate is 1,3-xylylene diisocyanate and 1,4-xylylene diisocyanate, and more preferably 1,3-xylylene diisocyanate.

[0079] Examples of modified forms include polymers, isocyanurate modified forms, allophanate modified forms, polyol adducts, biuret modified forms, urea modified forms, oxadiazinetrione modified forms, and carbodiimide modified forms. These can be used individually or in combination of two or more. From the viewpoint of adhesive stability, preferred modified forms include isocyanurate modified forms, allophanate modified forms, polyol adducts, and biuret modified forms, and more preferably isocyanurate modified forms, allophanate modified forms, and polyol adducts. That is, preferred derivatives of xylylene diisocyanate include polyol adducts of xylylene diisocyanate, allophanate modified forms of xylylene diisocyanate, and isocyanurate modified forms of xylylene diisocyanate.

[0080] Polyol adducts of xylylene diisocyanate can be obtained, for example, by urethane reaction of xylylene diisocyanate and a polyol in a predetermined equivalent ratio. Examples of polyols in the polyol adduct include the low molecular weight polyols mentioned above, preferably trihydric alcohols, and more preferably trimethylolpropane. These can be used individually or in combination of two or more. In the urethane reaction, the equivalent ratio of isocyanate groups of xylylene diisocyanate to hydroxyl groups of polyol (isocyanate group / hydroxyl group) is, for example, greater than 1, preferably 1.1 or more. Furthermore, the equivalent ratio of isocyanate groups of xylylene diisocyanate to hydroxyl groups of polyol (isocyanate group / hydroxyl group) is, for example, 30 or less, preferably 20 or less. This ensures that the isocyanate groups remain after the reaction. In other words, the polyol adduct of xylylene diisocyanate has isocyanate groups at its molecular termini.

[0081] Allophanate-modified xylylene diisocyanate is a compound containing one or more allophanate groups in one molecule. Allophanate-modified xylylene diisocyanate can be obtained, for example, by urethane-forming xylylene diisocyanate with the above monohydric alcohol and / or the above dihydric alcohol in a known manner, and then allophanate-forming the reaction product (urethane compound) in the presence of a known allophanate-forming catalyst.

[0082] Isocyanurate-modified xylylene diisocyanate is a compound containing one or more isocyanurate rings in one molecule. Isocyanurate-modified xylylene diisocyanate can be obtained, for example, by isocyanurating xylylene diisocyanate (monomer) in the presence of a known isocyanuration catalyst. Alternatively, isocyanurate-modified xylylene diisocyanate can be obtained, for example, by urethane-forming xylylene diisocyanate (monomer) with the above-mentioned monohydric alcohol and / or dihydric alcohol using a known method, and then isocyanurating the reaction product (urethane compound) in the presence of a known isocyanuration catalyst.

[0083] From the viewpoint of adhesive stability, more preferably, as derivatives of xylylene diisocyanate, are polyol adducts of xylylene diisocyanate and isocyanurate-modified compounds of xylylene diisocyanate, even more preferably are polyol adducts of xylylene diisocyanate, and particularly preferably are trimethylolpropane adducts of xylylene diisocyanate.

[0084] Polyisocyanate component (B) may optionally contain other polyisocyanates. These other polyisocyanates are polyisocyanates other than the xylylene diisocyanate derivatives described above.

[0085] Other polyisocyanates include, for example, polyisocyanate monomers and polyisocyanate derivatives (excluding xylylene diisocyanate derivatives). Examples of polyisocyanate monomers include the aliphatic polyisocyanates, aromatic polyisocyanates, and aromatic aliphatic polyisocyanates mentioned above. These polyisocyanate monomers can be used alone or in combination of two or more types. Examples of polyisocyanate derivatives (excluding xylylene diisocyanate derivatives) include modified products obtained by modifying the above polyisocyanate monomers (excluding xylylene diisocyanate) by known methods. Examples of polyisocyanate derivatives include polymers, isocyanurate modified products, allophanate modified products, polyol adducts, biuret modified products, urea modified products, oxadiazinetrione modified products, and carbodiimide modified products. Polymethylene polyphenylene polyisocyanate is another example of a polyisocyanate derivative. These can be used individually or in combination of two or more types.

[0086] From the viewpoint of adhesive stability, the content of other polyisocyanates is, for example, less than 50% by mass, preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 0% by mass, relative to the total amount of polyisocyanate component (B).

[0087] In other words, the polyisocyanate component (B) preferably does not contain other polyisocyanates and consists of a derivative of the above-mentioned xylylene diisocyanate.

[0088] The polyisocyanate component (B) may be dissolved and / or dispersed in the organic solvent described above. That is, the polyisocyanate component (B) may be prepared as a solution and / or dispersion. In other words, the curing agent of the two-component curable polyurethane adhesive composition may be a solution and / or dispersion of the polyisocyanate component (B) in an organic solvent.

[0089] In the organic solvent solution and / or dispersion of polyisocyanate component (B), the solid content concentration of polyisocyanate component (B) is, for example, 30% by mass or more, preferably 40% by mass or more. Alternatively, in the organic solvent solution and / or dispersion of polyisocyanate component (B), the solid content concentration of polyisocyanate component (B) is, for example, less than 100% by mass, preferably 90% by mass or less.

[0090] (3) Additives Polyurethane adhesive compositions may contain additives as needed. Examples of additives include urethane catalysts, antioxidants, UV absorbers, heat stabilizers, light stabilizers, crosslinking agents, antistatic agents, silane coupling agents, coating properties improvers, leveling agents, defoamers, curing accelerators, curing retarders, plasticizers, surfactants, pigments, fillers, organic particles, inorganic particles, metal particles, antifungal agents, processing aids, and anti-aging agents. These can be used individually or in combination of two or more types.

[0091] The additive may be contained in the polyol component (A), in the polyisocyanate component (B), or in both the polyol component (A) and the polyisocyanate component (B). The proportion of the additive is not particularly limited and can be set appropriately depending on the type of additive.

[0092] (4) Effects The polyurethane adhesive composition described above contains a polyisocyanate component (B) which is a derivative of xylylene diisocyanate. Therefore, according to the polyurethane adhesive composition described above, a polyurethane adhesive with excellent adhesive stability can be obtained.

[0093] 3. Polyurethane adhesive The polyurethane adhesive is formed from the polyurethane adhesive composition described above. More specifically, the polyurethane adhesive is obtained by curing (crosslinking) the polyurethane adhesive composition described above. That is, the polyurethane adhesive is a reaction product (cured resin) obtained by the reaction (curing reaction) between a polyol component (A) and a polyisocyanate component (B).

[0094] Furthermore, polyurethane adhesives possess tackiness (pressure-sensitive adhesion and tackiness). In other words, the reaction product (cured resin) of the polyol component (A) and the polyisocyanate component (B) is tacky. Polyurethane adhesives are distinguished from polyurethane adhesives (polyurethane resins that adhere to substrates due to a urethane reaction).

[0095] There are no particular limitations on the method for obtaining the polyurethane adhesive, but for example, the above polyurethane adhesive composition may be applied to the surface of a substrate and heat-cured.

[0096] More specifically, in this method, if the polyurethane adhesive composition is a two-component curing type polyurethane adhesive composition, first, a polyol component (A) as the main component and a polyisocyanate component (B) as the curing agent are blended together.

[0097] The mixing ratio of polyol component (A) and polyisocyanate component (B) is adjusted according to the equivalent ratio. For example, from the viewpoint of obtaining excellent adhesive strength, the equivalent ratio (NCO / OH) of isocyanate groups of polyisocyanate component (B) to hydroxyl groups of polyol component (A) is, for example, 0.03 or more, preferably 0.05 or more, and more preferably 0.1 or more. Also, from the viewpoint of obtaining excellent adhesive strength, the equivalent ratio (NCO / OH) of isocyanate groups of polyisocyanate component (B) to hydroxyl groups of polyol component (A) is, for example, 1.0 or less, preferably less than 1.0, more preferably 0.8 or less, and even more preferably 0.4 or less.

[0098] Furthermore, on a mass basis, the amount of polyisocyanate component (B) is, for example, 0.01 parts by mass or more, preferably 0.1 parts by mass or more, per 100 parts by mass of polyol component (A). Also, the amount of polyisocyanate component (B) is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, per 100 parts by mass of polyol component (A).

[0099] The mixing conditions for the polyol component (A) and the polyisocyanate component (B) are not particularly limited. The polyol component (A) and the polyisocyanate component (B) are mixed, for example, at room temperature. This yields a mixture of the polyol component (A) and the polyisocyanate component (B).

[0100] Furthermore, in this method, the above-mentioned additives (such as urethane catalysts) can be added to the mixture of polyol component (A) and polyisocyanate component (B) as needed. The additives may be added to polyol component (A) and / or polyisocyanate component (B) before mixing them. Alternatively, the additives may be added simultaneously with the mixing of polyol component (A) and polyisocyanate component (B). Alternatively, the additives may be added to the mixture after mixing polyol component (A) and polyisocyanate component (B). The mixing ratio of the additives is not particularly limited and can be set appropriately depending on the type of additive.

[0101] Furthermore, in this method, the viscosity of the mixture can be adjusted by adding the above-mentioned organic solvent to the mixture of polyol component (A) and polyisocyanate component (B) as needed. The amount of organic solvent added is not particularly limited and can be adjusted as appropriate.

[0102] This yields a mixture of polyurethane adhesive compositions (a mixture of polyol component (A) and polyisocyanate component (B)).

[0103] Next, in this method, a mixture of polyurethane adhesive compositions (a mixture of polyol component (A) and polyisocyanate component (B)) is applied to the substrate.

[0104] The substrate is not particularly limited, but examples include paper, cloth, leather, wood, resin sheets, rubber sheets, and metal sheets. Resin sheets are preferred as the substrate. The substrate may be surface-treated as needed. Examples of surface treatments include corona discharge treatment and primer treatment. The thickness of the substrate is not particularly limited and is set appropriately according to the purpose and application. The thickness of the substrate is, for example, 1 to 1000 μm.

[0105] The method of applying the polyurethane adhesive composition is not particularly limited. Examples of application methods include dip coating, spray coating, roll coating, doctor blade coating, screen printing, bar coating, and casting.

[0106] The above coating process forms a film of the polyurethane adhesive composition on the surface of the substrate. The dry thickness of the polyurethane adhesive composition film is, for example, 5 μm or more, preferably 8 μm or more. Alternatively, the dry thickness of the polyurethane adhesive composition film is, for example, 50 μm or less, preferably 20 μm or less.

[0107] Subsequently, in this method, the coating film of the polyurethane adhesive composition is heated. This causes the polyurethane adhesive composition to harden (crosslink).

[0108] The heating temperature is, for example, 23°C or higher, preferably 80°C or higher. The heating temperature is, for example, 180°C or lower, preferably 140°C or lower. The heating time is, for example, 30 seconds or more, preferably 1 minute or more. The heating time is, for example, 1 hour or less, preferably 0.5 hours or less.

[0109] The polyurethane adhesive composition hardens (crosslinks) on the substrate through the above coating and heating process. As a result, a polyurethane adhesive is obtained as a cured product (resin cured product) of the polyurethane adhesive composition (uncured resin composition).

[0110] The polyurethane adhesive is aged as needed. The aging temperature is, for example, 23°C or higher, preferably 40°C or higher. The aging temperature is, for example, 100°C or lower, preferably 80°C or lower. The aging time is, for example, 12 hours or more, preferably 1 day or more. The aging time is, for example, 14 days or less, preferably 7 days or less. The aging humidity (relative humidity) is, for example, 10% or higher, preferably 40% or higher. The aging humidity (relative humidity) is, for example, 80% or less, preferably 60% or less.

[0111] The polyurethane adhesive described above is formed from the polyurethane adhesive composition described above. Therefore, the polyurethane adhesive described above has excellent adhesive stability.

[0112] Therefore, polyurethane adhesives are suitably used in various industrial fields where the above physical properties are required. For example, polyurethane adhesives are suitably used in the information equipment field, housing field, building materials field, automotive field, railway field, lifestyle field, and healthcare field. [Examples]

[0113] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" and "%" are based on mass. Furthermore, specific numerical values ​​such as blending ratios (content), physical properties, and parameters used in the following description may be replaced with the corresponding upper limits (numerical values ​​defined as "less than or equal to" or "less than") or lower limits (numerical values ​​defined as "greater than or equal to" or "greater than") of the blending ratios (content), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above.

[0114] 1. Polyurethane polyol (a) (1) Raw material polyol (a1)

[0115] Preparation Example A-1: ​​Polyether Polyol A Actcol T-3000 (trade name, polyoxypropylene polyol, number average molecular weight 3000, average number of hydroxyl groups 3, manufactured by Mitsui Chemicals) and Actcol T-1500 (trade name, polyoxypropylene polyol, number average molecular weight 1500, average number of hydroxyl groups 3, manufactured by Mitsui Chemicals) were prepared. 100 parts by mass of Actcol T-3000 and 11.1 parts by mass of Actcol T-1500 were mixed. A polyether polyol with a number average molecular weight of 2850 was obtained from this mixture. Hereinafter, this polyether polyol (number average molecular weight 2850, average number of hydroxyl groups 3) was referred to as polyether polyol A (polyether A, PPT2850).

[0116] Preparation Example A-2 Polyester Polyol A Takelac LNB800 (product name, abbreviation LNB800, polyester polyol, number average molecular weight 800, average number of hydroxyl groups 2, condensate of neopentyl glycol (NPG) and polybasic acid (adipic acid), manufactured by Mitsui Chemicals) was prepared. This was referred to as polyester polyol A (polyester A).

[0117] Preparation Example A-3 HDI Hexamethylene diisocyanate (monomer) was prepared.

[0118] 2. Polyisocyanate component (B) Preparation example B-1 (XDI-TMP) Takenate D-110N (product name, trimethylolpropane adduct of 1,3-xylylene diisocyanate (XDI-TMP), manufactured by Mitsui Chemicals) was prepared.

[0119] Preparation Example B-2 (XDI Isocyanurate) Takenate D-131N (product name, isocyanurate modified form of 1,3-xylylene diisocyanate (XDI isocyanurate), manufactured by Mitsui Chemicals) was prepared.

[0120] Preparation Example B-3 (XDI Allophanate) In accordance with the descriptions in paragraphs

[0155] to

[0159] of Japanese Patent Publication No. 2021-85010, an allophanate modified form of XDI (1,3-xylylene diisocyanate) (XDI allophanate) was prepared.

[0121] More specifically, in a 1-liter four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube, 100 parts by mass of 1,3-xylylene diisocyanate (XDI), 15.8 parts by mass of isobutanol (IBA), 0.06 parts by mass of tris(2-ethylhexyl) phosphite (antioxidant), and 0.06 parts by mass of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (antioxidant) were charged under a nitrogen atmosphere to obtain a mixture. The equivalent ratio of isocyanate groups of XDI to hydroxyl groups of IBA (isocyanate groups / hydroxyl groups) was 5. The mixture was then reacted at 75°C for 3.5 hours to obtain the reaction solution.

[0122] Next, 0.06 parts by mass of XK-628 (trade name, manufactured by Kusumoto Chemical Co., Ltd., bismuth carboxylate, bismuth content 31% by mass) was added to the above reaction solution as an allophanate catalyst. Then, the above reaction solution was subjected to an allophanate reaction at 90°C for 11 hours.

[0123] Furthermore, it was confirmed that almost all urethane bonds in the reaction solution were converted to allophanate bonds. Specifically, in the IR spectrum, it was confirmed that the IR ratio of urethane groups to allophanate groups was 0.1 or less.

[0124] Subsequently, 0.10 parts by mass of o-toluenesulfonamide (a reaction terminating agent) was added to the reaction solution to stop the allophanate reaction. Then, unreacted isobutanol and XDI were removed from the reaction solution by distillation using a thin-film distillation apparatus (vacuum: 0.05 kPa, temperature: 150°C). This yielded the allophanate-modified product of XDI. Solvent (ethyl acetate) was added to the allophanate-modified product of XDI to adjust the solid content concentration to 75% by mass.

[0125] Preparation Example B-4 (XDI Biuret) Takenate A-14 (product name, biuret-modified 1,3-xylylene diisocyanate (XDI biuret), manufactured by Mitsui Chemicals) was prepared.

[0126] Preparation example B-5 (HDI-TMP) Takenate D-160N (product name, trimethylolpropane adduct of hexamethylene diisocyanate (HDI-TMP), manufactured by Mitsui Chemicals) was prepared. Preparation Example B-6 (HDI Isocyanurate) Takenate D-170N (product name, isocyanurate modified form of hexamethylene diisocyanate (HDI isocyanurate), manufactured by Mitsui Chemicals) was prepared. Preparation Example B-7 (HDI Allophanate) Takenate D-178NL (product name, allophanate modified hexamethylene diisocyanate (HDI allophanate), manufactured by Mitsui Chemicals) was prepared.

[0127] 3. Adhesive composition and adhesive Examples 1-6, Reference Example 7 ~10 and Comparative Examples 1-3 (1) Polyurethane polyol The raw material polyisocyanate (a2) and raw material polyol (a1) were combined according to the formulations described in Tables 1 and 2. These were mixed in the proportions shown in Tables 1 and 2, and then a urethane catalyst (dibutyltin dilaurate) was added. The amount of urethane catalyst was 100 ppm relative to the total amount of raw material polyisocyanate (a2), raw material polyol (a1), and urethane catalyst.

[0128] Furthermore, the proportion of hydroxyl groups derived from polyether polyol (a1-1) was 56.7 mol% and the proportion of hydroxyl groups derived from polyester polyol (a1-2) was 43.3 mol% relative to the total moles of hydroxyl groups derived from both polyether polyol (a1-1) and polyester polyol (a1-2). In addition, the equivalent ratio of isocyanate groups of raw material polyisocyanate (a2) to hydroxyl groups of raw material polyol (a1) (a2 / a1)(NCO / OH) was 0.74.

[0129] These mixtures were heated to 75°C and allowed to undergo a urethane reaction for 15 hours, after which the disappearance of the isocyanate groups was confirmed. This yielded a polyurethane polyol as the reaction product. The polyurethane polyol was dissolved in ethyl acetate. This yielded a solution of polyurethane polyol (solid content concentration 51% by mass).

[0130] (2) Polyurethane adhesive composition A polyurethane adhesive composition (uncured resin composition) was prepared by combining a polyol component (A) and a polyisocyanate component (B) according to the formulations described in Tables 1 and 2. Then, the polyol component (A) and the polyisocyanate component (B) were mixed. The mixing ratio was adjusted so that the equivalent ratio (B / A) (NCO / OH) of the isocyanate groups of the polyisocyanate component (B) to the hydroxyl groups of the polyol component (A) was as shown in Tables 1 and 2. This resulted in obtaining a mixture of polyurethane adhesive compositions.

[0131] (3) Polyurethane adhesive A mixture of polyurethane adhesive compositions was applied to a polyethylene terephthalate (PET) film. The amount of polyurethane adhesive composition applied was adjusted so that the dry thickness of the coating film was 20 μm.

[0132] The polyurethane adhesive composition was then heated at 110°C for 2 minutes to react and cure. This cured the polyurethane adhesive composition, yielding a polyurethane adhesive. The polyurethane adhesive was covered with a release film and aged for 2 days in a constant temperature and humidity chamber at 23°C and 60% relative humidity.

[0133] 4. Evaluation (1) Adhesive strength stability The polyurethane adhesive was cut into 25mm wide strips. The release film was peeled off the polyurethane adhesive. The polyurethane adhesive was pressed onto a glass plate, and a 2kg roller was rolled over the polyurethane adhesive. This compressed the polyurethane adhesive against the glass plate.

[0134] The polyurethane adhesive and glass plate were subjected to stability tests. Specifically, the polyurethane adhesive and glass plate were left standing under the following conditions (a), (b), and (c).

[0135] (a) Room temperature (23°C), normal humidity (50% RH), 10 days (b) Normal temperature (23℃), normal humidity (50%RH), 14 days (c) High temperature (60℃), high humidity (90%RH), 14 days

[0136] Then, before and after the stability tests described in (a) to (c) above, the polyurethane adhesive and glass plate were peeled using a tensile testing machine (tensile speed 300 mm / min, peel angle 180°). This allowed us to measure the adhesive strength of the polyurethane adhesive before and after the stability tests. Subsequently, the adhesion retention rate after the stability tests was calculated using the following formula.

[0137] Adhesion retention rate (%) = [Adhesion after stability test (N / 25mm) / Adhesion before stability test (N / 25mm)] × 100

[0138] The adhesive strength stability was evaluated according to the following criteria. The results are shown in Tables 1 and 2. ◎; Adhesion retention rate is over 90% but less than 110%. ○; Adhesion retention rate is over 80% but 90% or less, or 110% or more but less than 120%. △; Adhesion retention rate is over 70% but 80% or less, or 120% or more but less than 130%. ×; Adhesion retention rate is 70% or less, or 130% or more.

[0139] [Table 1]

[0140] [Table 2]

Claims

1. This is a polyurethane adhesive composition containing a polyol component (A) and a polyisocyanate component (B). The polyol component (A) contains polyurethane polyol (a), The polyurethane polyol (a) contains structural units derived from polyether polyol (a1-1) and structural units derived from polyester polyol (a1-2), The polyisocyanate component (B) contains a derivative of xylylene diisocyanate, A polyurethane adhesive composition in which the equivalent ratio (NCO / OH) of isocyanate groups of polyisocyanate component (B) to hydroxyl groups of polyol component (A) is 0.05 or more and 0.9 or less.

2. The derivative of the xylylene diisocyanate is The polyurethane adhesive composition according to claim 1, comprising at least one selected from the group consisting of a polyol adduct of xylylene diisocyanate, an allophanate modified form of xylylene diisocyanate, and an isocyanurate modified form of xylylene diisocyanate.

3. A polyurethane adhesive formed from the polyurethane adhesive composition described in claim 1.

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