Structural polyurethane adhesive

Abstract

To provide a structural polyurethane adhesive having excellent adhesive properties.SOLUTION: There is provided a structural polyurethane adhesive containing a polyisocyanate component and a polyol component. The polyisocyanate component contains a first isocyanate component and a second isocyanate component. The first isocyanate component contains a first isocyanate group terminal prepolymer. The first isocyanate group terminal prepolymer is a reaction product of a first raw material polyisocyanate comprising an aromatic polyisocyanate and a first raw material polyol containing a polytetramethylene ether polyol. The second isocyanate component contains a second isocyanate group terminal prepolymer and / or a derivative of an aliphatic polyisocyanate. The second isocyanate group terminal prepolymer is a reaction product of a second raw material polyisocyanate containing an aromatic aliphatic polyisocyanate and / or aliphatic polyisocyanate and a second raw material polyol containing a polyoxypropylene polyol. The amount of the second isocyanate component is 3 mass% or more and 25 mass% or less based on the polyisocyanate component and the polyol component contains a low molecular weight polyol and a high molecular weight polyol.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to structural polyurethane adhesives. [Background technology]

[0002] Structural adhesives have traditionally been used to bond multiple components in structures. Examples of such structures include automobiles and buildings. Examples of structural adhesives include two-component curing structural polyurethane adhesives containing a base agent (component 1) and a curing agent (component 2).

[0003] More specifically, the following formulation has been proposed for a structural polyurethane adhesive: The curing agent (component 1) contains polyoxypropylene triol and 1,4-butanediol. The base component (component 2) contains a polymer having free isocyanate groups and a carbodiimide of 4,4'-methylenediphenyl diisocyanate (MDI). The polymer having free isocyanate groups contains a reaction product of 4,4'-methylenediphenyl diisocyanate (MDI) with polyoxypropylene diol and polyoxypropylene polyoxyethylene triol (see, for example, Patent Document 1 (Example 1)). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2015-531020 Summary of the Invention [Problem to be solved by the invention]

[0005] However, structural polyurethane adhesives are required to have even better adhesive properties. do.

[0006] The present invention is a structural polyurethane adhesive with excellent adhesive properties. [Means for solving the problem]

[0007] The present invention [1] is a composition containing a polyisocyanate component and a polyol component, wherein the polyisocyanate component contains a first isocyanate component and a second isocyanate component, the first isocyanate component contains a first isocyanate group-terminated prepolymer, the first isocyanate group-terminated prepolymer is a reaction product of a first raw material polyisocyanate made of an aromatic polyisocyanate and a first raw material polyol containing a polytetramethylene ether polyol, and the second isocyanate component contains a second isocyanate group-terminated prepolymer, and / or a structural polyurethane adhesive comprising a derivative of an aliphatic polyisocyanate, wherein the second isocyanate group-terminated prepolymer is a reaction product of a second raw material polyisocyanate comprising an araliphatic polyisocyanate and / or an aliphatic polyisocyanate and a second raw material polyol comprising a polyoxypropylene polyol, the second isocyanate component being 3% by mass or more and 25% by mass or less relative to the polyisocyanate component, and the polyol component comprising a low-molecular-weight polyol and a high-molecular-weight polyol.

[0008] The present invention [2] includes the structural polyurethane adhesive according to the above [1], in which the first raw material polyol further includes polyoxypropylene polyol.

[0009] The present invention [3] includes the structural polyurethane adhesive according to the above [2], in which the terminal hydroxyl groups of the polyoxypropylene polyol are primary hydroxyl groups.

[0010] The present invention [4] includes a structural polyurethane adhesive according to any one of [2] to [3] above, wherein the first raw material polyol includes a polyoxypropylene polyol having an average number of hydroxyl groups of 2 and a polyoxypropylene polyol having an average number of hydroxyl groups of 3.

[0011] The present invention [5] comprises the structural polyurethane adhesive according to any one of [1] to [4] above, wherein the polyisocyanate component further comprises a third isocyanate component, and the third isocyanate component is a carbodiimide-modified aromatic polyisocyanate.

[0012] The present invention [6] comprises the structural polyurethane adhesive according to any one of [1] to [5] above, wherein the derivative of the aliphatic polyisocyanate comprises at least one selected from the group consisting of isocyanurate-modified aliphatic polyisocyanates, allophanate-modified aliphatic polyisocyanates, isocyanurate-allophanate-modified aliphatic polyisocyanates, and biuret-modified aliphatic polyisocyanates.

[0013] The present invention [7] comprises a structural polyurethane adhesive according to any one of the above [1] to [6], in which the polytetramethylene ether polyol is present in an amount of 5% by mass or more and 50% by mass or less relative to the total amount of the first raw material polyol.

[0014] The present invention [8] comprises the structural polyurethane adhesive according to any one of the above [1] to [7], wherein the high molecular weight polyol of the polyol component comprises a polyoxypropylene polyol, and the terminal hydroxyl groups of the polyoxypropylene polyol contained in the high molecular weight polyol are primary hydroxyl groups.

[0015] The present invention [9] includes the structural polyurethane adhesive according to any one of the above [1] to [8], which is a two-component curing adhesive comprising a base agent containing the polyisocyanate component and a curing agent containing the polyol component.

[0016] The present invention

[10] includes the structural polyurethane adhesive according to any one of the above [1] to [9], which is a solvent-free adhesive. [Effects of the Invention]

[0017] The structural polyurethane adhesive of the present invention contains a polyisocyanate component and a polyol component, and the polyisocyanate component contains a first isocyanate component and a second isocyanate component. The first isocyanate component contains a first isocyanate-terminated prepolymer, and the first isocyanate-terminated prepolymer is a reaction product of a first raw polyisocyanate made of an aromatic polyisocyanate and a first raw polyol containing polytetramethylene ether polyol. The second isocyanate component contains a second isocyanate-terminated prepolymer and / or a derivative of an aliphatic polyisocyanate, and the second isocyanate-terminated prepolymer is a reaction product of a second raw polyisocyanate containing an araliphatic polyisocyanate and / or an aliphatic polyisocyanate and a second raw polyol containing a polyoxypropylene polyol, and the second isocyanate component accounts for 3 to 25% by mass of the polyisocyanate component. Furthermore, since the polyol component contains a low molecular weight polyol and a high molecular weight polyol, the structural polyurethane adhesive of the present invention has excellent adhesive properties. DETAILED DESCRIPTION OF THE INVENTION

[0018] The structural polyurethane adhesive of the present invention is a structural adhesive as defined in JIS K 6800 (1985). Specifically, the structural polyurethane adhesive is a "reliable adhesive that can withstand large loads for long periods of time."

[0019] More specifically, the structural polyurethane adhesive contains a polyisocyanate component and a polyol component as essential components. The polyisocyanate component is a component containing free isocyanate groups. The polyol component is a component containing free hydroxyl groups.

[0020] The structural polyurethane adhesive may be a one-component curing adhesive in which a polyisocyanate component and a polyol component are premixed. Alternatively, the structural polyurethane adhesive may be a two-component curing adhesive comprising a base component (component A) containing a polyisocyanate component and a curing agent (component B) containing a polyol component. In a two-component curing adhesive, the base component and curing agent are prepared separately and mixed at the time of use. From the viewpoints of workability, handling, etc., the structural polyurethane adhesive is preferably a two-component curing adhesive.

[0021] The polyisocyanate component contains a first isocyanate component and a second isocyanate component. The first isocyanate component contains a urethane prepolymer having two or more isocyanate groups at its molecular terminals (hereinafter referred to as a first isocyanate group-terminated prepolymer).

[0022] More specifically, the first isocyanate component contains a first isocyanate-terminated prepolymer. The first isocyanate-terminated prepolymer is a reaction product of a first raw material polyisocyanate and a first raw material polyol. The first raw material polyisocyanate and the first raw material polyol react to form an excess of isocyanate groups relative to hydroxyl groups.

[0023] The first raw material polyisocyanate is an aromatic polyisocyanate, such as an aromatic polyisocyanate monomer or an aromatic polyisocyanate derivative.

[0024] Examples of aromatic polyisocyanate monomers include aromatic diisocyanates, such as tolylene diisocyanate, phenylene diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate, toluidine diisocyanate, and diphenyl ether diisocyanate. These may be used alone or in combination of two or more.

[0025] Examples of aromatic polyisocyanate derivatives include modified products obtained by modifying the above-mentioned aromatic polyisocyanate monomers using known methods. More specifically, examples of aromatic polyisocyanate derivatives include uretdione-modified products, isocyanurate-modified products, allophanate-modified products, polyol-modified products, biuret-modified products, urea-modified products, oxadiazinetrione-modified products, and carbodiimide-modified products. Further, examples of aromatic polyisocyanate derivatives include polymethylene polyphenylene polyisocyanate. These can be used alone or in combination of two or more types.

[0026] These aromatic polyisocyanates can be used alone or in combination of two or more. From the viewpoint of adhesive properties, the aromatic polyisocyanate is preferably an aromatic polyisocyanate monomer, more preferably an aromatic diisocyanate, and even more preferably diphenylmethane diisocyanate.

[0027] In other words, the first raw material polyisocyanate preferably comprises a diphenylmethane diisocyanate monomer from the viewpoint of adhesive properties.

[0028] The first raw material polyol contains polytetramethylene ether polyol as an essential component.

[0029] Examples of polytetramethylene ether polyols include ring-opening polymers (crystalline polytetramethylene ether glycols) obtained by cationic polymerization of tetrahydrofuran, and amorphous (non-crystalline) polytetramethylene ether glycols in which alkyl-substituted tetrahydrofuran or dihydric alcohols (described later) are copolymerized with polymerization units of tetrahydrofuran or the like.

[0030] The term "amorphous (non-crystalline)" refers to a substance that is liquid at room temperature (25°C).

[0031] The number average molecular weight of the polytetramethylene ether polyol in the first raw material polyol is, for example, 200 or more, preferably 300 or more, and more preferably 500 or more. The number average molecular weight of the polytetramethylene ether polyol in the first raw material polyol is, for example, 10,000 or less, more preferably 8,000 or less, even more preferably 5,000 or less, and particularly preferably 2,000 or less. The number average molecular weight is a polystyrene-equivalent molecular weight measured by gel permeation chromatography (the same applies hereinafter).

[0032] The hydroxyl equivalent of the polytetramethylene ether polyol is, for example, 150 or more, preferably 200 or more. The hydroxyl equivalent of the polytetramethylene ether polyol is, for example, 5000 or less, preferably 2000 or less, more preferably 1000 or less, and even more preferably 600 or less. The hydroxyl equivalent can be calculated from the hydroxyl value.

[0033] The average number of hydroxyl groups in the polytetramethylene ether polyol is, for example, 1.8 or more, or preferably 2 or more. The average number of hydroxyl groups in the polytetramethylene ether polyol is, for example, 3 or less, or preferably 2.5 or less.

[0034] The hydroxyl value and hydroxyl equivalent can be measured, for example, in accordance with Method A or Method B of JIS K 1557-1 (2007). The average number of hydroxyl groups can be calculated from the hydroxyl value, hydroxyl equivalent, and molecular weight. The hydroxyl value, hydroxyl equivalent, and average number of hydroxyl groups can also be calculated from the charging ratio of the raw material components (the same applies below).

[0035] The proportion of polytetramethylene ether polyol relative to the total amount of the first raw material polyol is, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, particularly preferably 30% by mass or more, and is, for example, 50% by mass or less, preferably 40% by mass or less, more preferably 35% by mass or less. If the proportion of polytetramethylene ether polyol is within the above range, excellent adhesive strength is achieved.

[0036] More preferably, the first raw material polyol further contains polyoxypropylene polyol.

[0037] Examples of polyoxypropylene polyols include polyoxypropylene polyols having an average number of hydroxyl groups of 2 and 3. As the polyoxypropylene polyol, preferably, a polyoxypropylene polyol having an average number of hydroxyl groups of 2 and a polyoxypropylene polyol having an average number of hydroxyl groups of 3 are used in combination.

[0038] The number average molecular weight of the polyoxypropylene polyol having an average number of 2 hydroxyl groups is, for example, 200 or more, preferably 300 or more, and more preferably 500 or more. The number average molecular weight of the polyoxypropylene polyol having an average number of 2 hydroxyl groups is usually, for example, 10,000 or less, preferably 5,000 or less, more preferably 2,000 or less, and even more preferably 1,500 or less.

[0039] The hydroxyl equivalent of the polyoxypropylene polyol having an average number of 2 hydroxyl groups is, for example, 150 or more, preferably 300 or more, and more preferably 400 or more. The hydroxyl equivalent of the polyoxypropylene polyol having an average number of 2 hydroxyl groups is, for example, 5000 or less, preferably 3000 or less, more preferably 2000 or less, even more preferably 1000 or less, and particularly preferably 750 or less.

[0040] The number average molecular weight of the polyoxypropylene polyol having an average of 3 hydroxyl groups is, for example, 200 or more, preferably 300 or more, and more preferably 500 or more. The number average molecular weight of the polyoxypropylene polyol having an average of 3 hydroxyl groups is usually, for example, 10,000 or less, preferably 5,000 or less, more preferably 2,000 or less, and even more preferably 1,500 or less.

[0041] The hydroxyl equivalent of the polyoxypropylene polyol having an average number of 3 hydroxyl groups is, for example, 150 or more, preferably 200 or more, and more preferably 300 or more. The hydroxyl equivalent of the polyoxypropylene polyol having an average number of 3 hydroxyl groups is, for example, 3000 or less, preferably 2000 or less, more preferably 1000 or less, and even more preferably 500 or less.

[0042] When a polyoxypropylene polyol having an average number of 2 hydroxyl groups and a polyoxypropylene polyol having an average number of 3 hydroxyl groups are used in combination (excluding EO-capped polyoxypropylene polyols described below), the amount of the polyoxypropylene polyol having an average number of 2 hydroxyl groups is, for example, 50 parts by mass or more, preferably 55 parts by mass or more, per 100 parts by mass of the total amount of these components. The amount of the polyoxypropylene polyol having an average number of 2 hydroxyl groups is, for example, 90 parts by mass or less, preferably 75 parts by mass or less. The amount of the polyoxypropylene polyol having an average number of 3 hydroxyl groups is, for example, 10 parts by mass or more, preferably 25 parts by mass or more. The amount of the polyoxypropylene polyol having an average number of 3 hydroxyl groups is, for example, less than 50 parts by mass, preferably 45 parts by mass or less.

[0043] As the first raw material polyol, the polyoxypropylene polyol may have its molecular terminals modified with ethylene oxide (EO) (hereinafter, sometimes referred to as EO capping). In this case, the terminal hydroxyl groups of the polyoxypropylene polyol are primary hydroxyl groups. The EO-capped polyoxypropylene polyol may have a polyoxyethylene unit modified in the middle of the polyoxypropylene chain.

[0044] When the polyoxypropylene polyol contained in the first raw material polyol is the above-mentioned polyoxypropylene polyol having an average number of 2 or 3 hydroxyl groups, it may contain only EO-capped polyoxypropylene polyol having an average number of 2 hydroxyl groups, or it may contain only EO-capped polyoxypropylene polyol having an average number of 3 hydroxyl groups, or it may contain both EO-capped polyoxypropylene polyol having an average number of 2 hydroxyl groups and EO-capped polyoxypropylene polyol having an average number of 3 hydroxyl groups.

[0045] The number average molecular weight of the EO-capped polyoxypropylene polyol having an average of 2 hydroxyl groups is, for example, 300 or more, preferably 500 or more, more preferably 1000 or more, and even more preferably 1500 or more. The number average molecular weight of the EO-capped polyoxypropylene polyol having an average of 2 hydroxyl groups is usually, for example, 10000 or less, preferably 5000 or less, and more preferably 3000 or less.

[0046] The hydroxyl equivalent of the EO-capped polyoxypropylene polyol having an average number of 2 hydroxyl groups is, for example, 300 or more, preferably 500 or more, and more preferably 1000 or more. The hydroxyl equivalent of the EO-capped polyoxypropylene polyol having an average number of 2 hydroxyl groups is, for example, 5000 or less, preferably 3000 or less, more preferably 2000 or less, and even more preferably 1500 or less.

[0047] The number average molecular weight of the EO-capped polyoxypropylene polyol having an average of 3 hydroxyl groups is, for example, 500 or more, preferably 1000 or more, more preferably 2000 or more, and even more preferably 4000 or more. The number average molecular weight of the EO-capped polyoxypropylene polyol having an average of 3 hydroxyl groups is usually, for example, 20000 or less, preferably 10000 or less, and more preferably 7500 or less.

[0048] The hydroxyl equivalent of the EO-capped polyoxypropylene polyol having an average of 3 hydroxyl groups is, for example, 500 or more, preferably 1000 or more, and more preferably 1500 or more. The hydroxyl equivalent of the EO-capped polyoxypropylene polyol having an average of 3 hydroxyl groups is, for example, 3000 or less, preferably 2000 or less.

[0049] In other words, the polyoxypropylene polyol contained in the first raw material polyol includes polyoxypropylene polyol (polyoxypropylene polyol not capped with EO) and / or EO-capped polyoxypropylene polyol.

[0050] The polyoxypropylene polyol contained in the first raw material polyol preferably contains a non-EO-capped polyoxypropylene polyol and an EO-capped polyoxypropylene polyol. In this case, the amount of the EO-capped polyoxypropylene polyol per 100 parts by mass of the non-EO-capped polyoxypropylene polyol is, for example, 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more, and is, for example, 80 parts by mass or less, preferably 70 parts by mass or less.

[0051] The polyoxypropylene polyol contained in the first raw material polyol more preferably includes a non-EO-capped polyoxypropylene polyol having functional groups of 2 and 3, and an EO-capped polyoxypropylene polyol having functional groups of 2 and 3. In this case, the amount of the EO-capped polyoxypropylene polyol having functional groups of 2 and 3 is, for example, 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more, and for example, 80 parts by mass or less, preferably 70 parts by mass or less, per 100 parts by mass of the non-EO-capped polyoxypropylene polyol having functional groups of 2 and 3.

[0052] The polyoxypropylene polyol contained in the first raw material polyol more preferably contains an un-EO-capped polyoxypropylene polyol having a functionality of 2, an un-EO-capped polyoxypropylene polyol having a functionality of 3, and an EO-capped polyoxypropylene polyol having a functionality of 2. In this case, per 100 parts by mass of the total of the un-EO-capped polyoxypropylene polyol having a functionality of 2 and the un-EO-capped polyoxypropylene polyol having a functionality of 3, the amount of the EO-capped polyoxypropylene polyol having a functionality of 2 is, for example, 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more, and for example, 80 parts by mass or less, preferably 70 parts by mass or less.

[0053] The number average molecular weight of the polyoxypropylene polyol (including EO-capped and non-EO-capped polyols) contained in the first raw material polyol is, for example, 200 or more, preferably 300 or more, and more preferably 400 or more. The number average molecular weight of the polyoxypropylene polyol contained in the first raw material polyol is, for example, 10,000 or less, preferably 8,000 or less, more preferably 5,000 or less, even more preferably 3,000 or less, and even more preferably 2,000 or less.

[0054] The hydroxyl equivalent of the polyoxypropylene polyol (including EO-capped and non-EO-capped polyols) contained in the first raw material polyol is, for example, 150 or more, or preferably 200 or more. The hydroxyl equivalent of the polyoxypropylene polyol contained in the first raw material polyol is, for example, 5000 or less, or preferably 2000 or less.

[0055] The polyoxypropylene polyol (including EO-capped and non-EO-capped polyols) contained in the first raw material polyol has an average number of hydroxyl groups of, for example, 1.5 or more, preferably 1.8 or more. The polyoxypropylene polyol contained in the first raw material polyol has an average number of hydroxyl groups of, for example, 3.5 or less, preferably 3.0 or less.

[0056] The ratio of polyoxypropylene polyol (including EO-capped and non-EO-capped) to the first raw material polyol is, for example, 20% by mass or more, preferably 40% by mass or more, more preferably 60% by mass or more, and for example, 90% by mass or less, preferably 80% by mass or less, more preferably 70% by mass or less.

[0057] The first raw material polyol may also contain a low molecular weight polyol as an optional component.

[0058] The molecular weight of the low-molecular-weight polyol in the first raw material polyol (hereinafter referred to as the first low-molecular-weight polyol) is less than 200, preferably 180 or less.

[0059] Examples of the first low-molecular-weight polyol 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, 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 may be used alone or in combination.

[0060] The content of the first low-molecular-weight polyol is appropriately selected within a range that does not impair the excellent effects of the present invention. More specifically, the content of the first low-molecular-weight polyol is, for example, 30 parts by mass or less, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and particularly preferably 0 parts by mass, relative to 100 parts by mass of the total amount of the first raw material polyol. That is, from the viewpoint of adhesive properties, the first raw material polyol preferably does not contain the first low-molecular-weight polyol and is composed of polytetramethylene ether polyol and polyoxypropylene polyol.

[0061] The first isocyanate-terminated prepolymer is obtained by reacting the first raw material polyisocyanate with the first raw material polyol by a known method. More specifically, the first raw material polyisocyanate and the first raw material polyol are mixed in a predetermined ratio and subjected to a urethane reaction.

[0062] In the urethanization reaction, the equivalent ratio (NCO / OH) of the isocyanate groups in the first raw material polyisocyanate to the hydroxyl groups in the first raw material polyol is, for example, greater than 1, preferably 1.5 or more, more preferably 2.0 or more, even more preferably 2.2 or more, and particularly preferably 2.5 or more. The equivalent ratio (NCO / OH) is, for example, 10 or less, preferably 5 or less, more preferably 3.0 or less.

[0063] In the urethanization reaction, a known polymerization method is employed. Examples of the polymerization method include bulk polymerization and solution polymerization. In bulk polymerization, for example, the above components are blended and reacted under a nitrogen atmosphere. In solution polymerization, for example, the above components are added to a known organic solvent under a nitrogen atmosphere and reacted. The reaction temperature is, for example, 50°C or higher and, for example, 120°C or lower, preferably 100°C or lower. The reaction time is, for example, 0.5 hours or higher, preferably 1 hour or higher, and, for example, 24 hours or lower, preferably 15 hours or lower. In solution polymerization, the blending ratio of the organic solvent is appropriately set depending on the purpose and application. In the urethanization reaction, bulk polymerization (solventless reaction) is preferably employed.

[0064] In the urethanization reaction, a known urethanization catalyst is added as needed. If necessary, unreacted polyisocyanate is removed by a known method. This produces a first isocyanate component containing a first isocyanate group-terminated prepolymer.

[0065] The first isocyanate group-terminated prepolymer is preferably a first isocyanate group-terminated prepolymer that is a reaction product of an aromatic polyisocyanate with a polytetramethylene ether polyol and a polyoxypropylene polyol, and more preferably a first isocyanate group-terminated prepolymer that is a reaction product of diphenylmethane diisocyanate with a polytetramethylene ether polyol and a polyoxypropylene polyol.

[0066] The first isocyanate component may contain, as necessary, free (unreacted) first raw material polyisocyanate, organic solvent, and urethane-forming catalyst. The free (unreacted) first raw material polyisocyanate, organic solvent, and urethane-forming catalyst may be removed by known removal means. Examples of removal means include extraction and distillation.

[0067] From the viewpoint of adhesive properties, the content of the free (unreacted) first raw material polyisocyanate is, for example, 35% by mass or less, preferably 30% by mass or less, based on the total amount of the polyisocyanate components. The content of the first isocyanate group-terminated prepolymer is, for example, 65% by mass or more, preferably 70% by mass or more, based on the total amount of the first isocyanate components.

[0068] The average number of isocyanate groups in the first isocyanate component (solid content) is, for example, 2 or more, preferably 2.1 or more. The average number of isocyanate groups in the first isocyanate component (solid content) is, for example, 4 or less, preferably 3 or less, and more preferably 2.8 or less.

[0069] The isocyanate group equivalent of the first isocyanate component (solid content) is, for example, 200 or more, preferably 400 or more. The isocyanate group equivalent of the first isocyanate component (solid content) is, for example, 2000 or less, preferably 1000 or less, more preferably 600 or less, and even more preferably 500 or less. The isocyanate group equivalent can be determined by Method A or Method B of JIS K 1603-1 (2007). The isocyanate group equivalent is synonymous with the amine equivalent.

[0070] The isocyanate group content (isocyanate group content (NCO%)) of the first isocyanate component (solid content) is, for example, 2.0 mass% or more, preferably 3.0 mass% or more, more preferably 5.0 mass% or more, even more preferably 6.0 mass% or more, and particularly preferably 7.0 mass% or more. The isocyanate group content of the first isocyanate component (solid content) is, for example, 10 mass% or less, preferably 9 mass% or less.

[0071] The ratio of the first isocyanate component to the polyisocyanate component is, for example, 30% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and particularly preferably 70% by mass or more. Alternatively, it is, for example, 95% by mass or less, preferably 89% by mass or less, more preferably 80% by mass or less, even more preferably 77% by mass or less, and particularly preferably 75% by mass or less. In other words, the first isocyanate component is the main component of the polyisocyanate component.

[0072] The first isocyanate component and the second isocyanate component (described later) may contain known additives (stabilizers) (described later) as needed.

[0073] The second isocyanate component contains a second isocyanate-terminated prepolymer and / or a derivative of an aliphatic polyisocyanate. The second isocyanate-terminated prepolymer is a urethane prepolymer having two or more isocyanate groups at the molecular end (hereinafter referred to as a second isocyanate-terminated prepolymer). The second isocyanate-terminated prepolymer is a reaction product of a second raw material polyisocyanate and a second raw material polyol. The second raw material polyisocyanate and the second raw material polyol react so that there is an excess of isocyanate groups relative to the hydroxyl groups.

[0074] The second raw material polyisocyanate comprises an aromatic aliphatic polyisocyanate and / or an aliphatic polyisocyanate.

[0075] Examples of araliphatic polyisocyanates include araliphatic polyisocyanate monomers. Examples of araliphatic polyisocyanate monomers include araliphatic diisocyanates. Examples of araliphatic diisocyanates include xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate, and ω,ω'-diisocyanato-1,4-diethylbenzene. Examples of xylylene diisocyanates include 1,3-xylylene diisocyanate and 1,4-xylylene diisocyanate. These can be used alone or in combination of two or more. A preferred araliphatic polyisocyanate is xylylene diisocyanate (XDI).

[0076] Examples of the aliphatic polyisocyanate include chain aliphatic polyisocyanates and alicyclic polyisocyanates.

[0077] Examples of the chain aliphatic polyisocyanate include chain aliphatic polyisocyanate monomers. Examples of the chain aliphatic polyisocyanate monomer include chain aliphatic diisocyanates. Examples of the chain aliphatic diisocyanates 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 may be used alone or in combination of two or more. Preferably, a chain aliphatic diisocyanate is used, more preferably, pentamethylene diisocyanate and hexamethylene diisocyanate are used, and particularly preferably, hexamethylene diisocyanate is used.

[0078] Examples of alicyclic polyisocyanates include alicyclic polyisocyanate monomers. Examples of alicyclic polyisocyanate monomers include alicyclic diisocyanates. Examples of alicyclic diisocyanates include isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), methylenebis(cyclohexylisocyanate) (H12MDI), and bis(isocyanatomethyl)cyclohexane (H6XDI). These can be used alone or in combination of two or more.

[0079] The araliphatic polyisocyanate and / or aliphatic polyisocyanate also includes derivatives of the above-mentioned monomers. Examples of the derivatives include derivatives of araliphatic polyisocyanate monomers, derivatives of linear aliphatic polyisocyanate monomers, and derivatives of alicyclic polyisocyanate monomers. Examples of the derivatives include modified products obtained by modifying the above-mentioned monomers using known methods. More specific examples of the derivatives include uretdione-modified products, isocyanurate-modified products, allophanate-modified products, polyol-modified products, biuret-modified products, urea-modified products, oxadiazinetrione-modified products, and carbodiimide-modified products. These can be used alone or in combination of two or more types.

[0080] These araliphatic polyisocyanates and / or aliphatic polyisocyanates can be used alone or in combination of two or more. From the viewpoint of adhesive properties, the araliphatic polyisocyanate and / or aliphatic polyisocyanate is preferably an araliphatic polyisocyanate or an aliphatic polyisocyanate, more preferably an aliphatic polyisocyanate, even more preferably a chain aliphatic polyisocyanate, particularly preferably a chain aliphatic polyisocyanate monomer, particularly preferably a chain aliphatic diisocyanate, and most preferably hexamethylene diisocyanate.

[0081] The second raw material polyol contains polyoxypropylene polyol as an essential component, and preferably consists of polyoxypropylene polyol.

[0082] In the second raw material polyol, examples of the polyoxypropylene polyol include the same polyoxypropylene polyols as those described above as the first raw material polyol.

[0083] In the second raw material polyol, the number average molecular weight of the polyoxypropylene polyol is, from the viewpoint of adhesive properties, 240 or more, preferably 300 or more, and more preferably 350 or more. Also, the number average molecular weight of the polyether polyol is, from the viewpoint of adhesive properties, 2000 or less, preferably 1000 or less, more preferably 800 or less, even more preferably 600 or less, and still more preferably 500 or less.

[0084] In the second raw material polyol, the hydroxyl equivalent of the polyoxypropylene polyol is, for example, 50 or more, preferably 100 or more, and more preferably 150 or more. In addition, in the second raw material polyol, the hydroxyl equivalent of the polyoxypropylene polyol is, for example, 1000 or less, preferably 500 or less, more preferably 400 or less, and even more preferably 300 or less.

[0085] In the second raw material polyol, the average number of hydroxyl groups of the polyoxypropylene polyol is, from the viewpoint of adhesive strength, for example, 1.5 or more, or preferably 1.8 or more, and, from the viewpoint of adhesive strength, for example, 4 or less, or preferably 3.5 or less.

[0086] The second isocyanate group-terminated prepolymer is obtained by the same method as that for the first isocyanate group-terminated prepolymer.

[0087] The second isocyanate group-terminated prepolymer is preferably a second isocyanate group-terminated prepolymer that is a reaction product of an araliphatic polyisocyanate and a polyoxypropylene polyol, or a second isocyanate group-terminated prepolymer that is a reaction product of an aliphatic polyisocyanate and a polyoxypropylene polyol, more preferably a second isocyanate group-terminated prepolymer that is a reaction product of an aliphatic polyisocyanate and a polyoxypropylene polyol, and even more preferably a second isocyanate group-terminated prepolymer that is a reaction product of hexamethylene diisocyanate and a polyoxypropylene polyol.

[0088] Examples of the aliphatic polyisocyanate in the derivative of aliphatic polyisocyanate (aliphatic polyisocyanate derivative) include those mentioned above. These can be used alone or in combination of two or more. From the viewpoint of adhesive properties, the aliphatic polyisocyanate in the aliphatic polyisocyanate derivative is preferably a chain aliphatic polyisocyanate, more preferably a chain aliphatic polyisocyanate monomer, and even more preferably a chain aliphatic diisocyanate, particularly preferably pentamethylene diisocyanate (PDI) or hexamethylene diisocyanate (HDI), and most preferably hexamethylene diisocyanate (HDI).

[0089] Examples of the derivative of aliphatic polyisocyanate (aliphatic polyisocyanate derivative) include those described above. These can be used alone or in combination of two or more. From the viewpoint of adhesive properties, the derivative of the aliphatic polyisocyanate derivative is preferably an isocyanurate-modified product, an allophanate-modified product, an isocyanurate-allophanate-modified product, or a biuret-modified product, more preferably an isocyanurate-modified product, an isocyanurate-allophanate-modified product, or a biuret-modified product. That is, the derivative of aliphatic polyisocyanate preferably contains an isocyanurate-modified product of aliphatic polyisocyanate, an allophanate-modified product of aliphatic polyisocyanate, an isocyanurate-allophanate-modified product of aliphatic polyisocyanate, or a biuret-modified product of aliphatic polyisocyanate. The derivative of aliphatic polyisocyanate more preferably includes at least one selected from the group consisting of isocyanurate-modified aliphatic polyisocyanates, allophanate-modified aliphatic polyisocyanates, isocyanurate-allophanate-modified aliphatic polyisocyanates, and biuret-modified aliphatic polyisocyanates. The derivative of aliphatic polyisocyanate is even more preferably at least one selected from the group consisting of isocyanurate-modified aliphatic polyisocyanates, isocyanurate-allophanate-modified aliphatic polyisocyanates, and biuret-modified aliphatic polyisocyanates.

[0090] From the viewpoint of adhesive properties, the aliphatic polyisocyanate derivative is preferably an isocyanurate-modified HDI, a biuret-modified HDI, or an isocyanurate-allophanate-modified PDI, more preferably an isocyanurate-modified HDI, or a biuret-modified HDI, and even more preferably an isocyanurate-modified HDI.

[0091] The isocyanurate-modified aliphatic polyisocyanate may include an allophanate-modified aliphatic polyisocyanate.Further, the allophanate-modified aliphatic polyisocyanate may include an isocyanurate-modified aliphatic polyisocyanate.

[0092] When the isocyanurate-modified aliphatic polyisocyanate contains an allophanate-modified aliphatic polyisocyanate, the proportion of the allophanate-modified aliphatic polyisocyanate is, for example, less than 10% by mass, preferably less than 5% based on the total amount of the isocyanurate-modified aliphatic polyisocyanate and the allophanate-modified aliphatic polyisocyanate. When the allophanate-modified aliphatic polyisocyanate contains an isocyanurate-modified aliphatic polyisocyanate, the proportion of the isocyanurate-modified aliphatic polyisocyanate is, for example, less than 10% by mass, preferably less than 5% based on the total amount of the isocyanurate-modified aliphatic polyisocyanate and the allophanate-modified aliphatic polyisocyanate.

[0093] The isocyanurate-allophanate modified aliphatic polyisocyanate contains 10% by mass or more of an isocyanurate modified aliphatic polyisocyanate and 10% by mass or more of an allophanate modified aliphatic polyisocyanate.

[0094] In the isocyanurate-allophanate modified aliphatic polyisocyanate, the isocyanurate modified aliphatic polyisocyanate accounts for preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, particularly preferably 55% by mass or more, and most preferably 60% by mass or more, based on the total amount of the isocyanurate-allophanate modified aliphatic polyisocyanate, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less. Furthermore, in the isocyanurate-allophanate modified aliphatic polyisocyanate, the allophanate modified aliphatic polyisocyanate accounts for preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, and is preferably 80% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, particularly preferably 45% by mass or less, and most preferably 40% by mass or less, based on the total amount of the isocyanurate-allophanate modified aliphatic polyisocyanate.

[0095] The isocyanurate-allophanate modified aliphatic polyisocyanate is preferably in excess of the isocyanurate modified aliphatic polyisocyanate over the allophanate modified aliphatic polyisocyanate.

[0096] The second isocyanate component may contain only either the second isocyanate group-terminated prepolymer or the derivative of an aliphatic polyisocyanate, or may contain both the second isocyanate group-terminated prepolymer and the derivative of an aliphatic polyisocyanate.

[0097] From the viewpoint of adhesive properties, the second isocyanate component preferably contains a second isocyanate-terminated prepolymer or a derivative of an aliphatic polyisocyanate, and more preferably contains only a derivative of an aliphatic polyisocyanate. The content of the second isocyanate-terminated prepolymer and / or the derivative of an aliphatic polyisocyanate is, for example, 95.0 mass% or more, preferably 99.0 mass% or more, and typically 100 mass% relative to the total amount of the second isocyanate component. In other words, the second isocyanate component preferably consists of a second isocyanate-terminated prepolymer and / or a derivative of an aliphatic polyisocyanate.

[0098] The second isocyanate component may contain, as necessary, a free (unreacted) second raw material polyisocyanate, an organic solvent, and a urethanization catalyst. The free (unreacted) second raw material polyisocyanate, the organic solvent, and the urethanization catalyst may be removed by known removal means. Examples of removal means include extraction and distillation. Preferably, the second isocyanate component is distilled, and from the viewpoint of improving adhesive strength, the second isocyanate component is more preferably thin-film distilled.

[0099] From the viewpoint of adhesive strength, the content of the free (unreacted) second raw material polyisocyanate is, for example, 5.0 mass % or less, or preferably 1.0 mass % or less, relative to the total amount of the second isocyanate component.

[0100] The second isocyanate component (solid content) has an average number of isocyanate groups of, for example, 1.5 or more, preferably 1.7 or more, more preferably 1.8 or more, and has an average number of isocyanate groups of, for example, 5.0 or less, preferably 4.0 or less, more preferably 3.7 or less.

[0101] The second isocyanate component (solid content) has an isocyanate group equivalent of, for example, 140 or more, preferably 150 or more, and more preferably 160 or more. The second isocyanate component (solid content) has an isocyanate group equivalent of, for example, 500 or less, preferably 480 or less, and more preferably 460 or less.

[0102] The isocyanate group content (isocyanate group content (NCO%)) of the second isocyanate component (solid content) is, for example, 8 mass % or more, preferably 8.7 mass % or more, more preferably 9.1 mass % or more. The isocyanate group content of the second isocyanate component (solid content) is, for example, 30 mass % or less, preferably 26 mass % or less.

[0103] The polyisocyanate component is prepared by mixing a first isocyanate component and a second isocyanate component.

[0104] The second isocyanate component is, relative to the polyisocyanate component, for example, 3% by mass or more, preferably 4% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, particularly preferably 10% by mass or more, and for example, 25% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less. When the proportion of the second isocyanate component is within the above range, particularly excellent adhesive properties can be obtained.

[0105] Relative to 100 parts by mass of the first isocyanate component, the amount of the second isocyanate component is, for example, 1 part by mass or more, preferably 3 parts by mass or more, more preferably 4 parts by mass or more, even more preferably 7 parts by mass or more, particularly preferably 11.1 parts by mass or more, especially preferably 11.2 parts by mass or more, and most preferably 12 parts by mass or more, and is, for example, 60 parts by mass or less, preferably 45 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less.

[0106] The polyisocyanate component preferably further contains a tertiary isocyanate component.

[0107] The third isocyanate component contains a carbodiimide-modified aromatic polyisocyanate, and preferably consists of a carbodiimide-modified aromatic polyisocyanate.

[0108] The carbodiimide-modified aromatic polyisocyanate is a reaction product of a carbodiimidization reaction of an aromatic polyisocyanate.

[0109] Examples of the aromatic polyisocyanate include the aromatic polyisocyanates described above as the first raw material polyisocyanate, more specifically, aromatic polyisocyanate monomers and derivatives thereof. From the viewpoint of adhesive properties, the aromatic polyisocyanate is preferably an aromatic polyisocyanate monomer, more preferably an aromatic diisocyanate, and even more preferably diphenylmethane diisocyanate.

[0110] The carbodiimidization reaction may be a decarboxylation condensation reaction, in which, for example, an aromatic polyisocyanate is heated in the presence of a carbodiimidization catalyst.

[0111] Alternatively, the third isocyanate component may be a commercially available carbodiimide-modified aromatic polyisocyanate, such as Coronate MX (a carbodiimide-modified diphenylmethane diisocyanate, isocyanate group content 29.0% by mass, manufactured by Tosoh Corporation).

[0112] The isocyanate group content of the carbodiimide-modified aromatic polyisocyanate in the third isocyanate component is, for example, 10% by mass or more, preferably 20% by mass or more, more preferably 25% by mass or more. The isocyanate group content of the carbodiimide-modified aromatic polyisocyanate in the third isocyanate component is, for example, 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less.

[0113] The viscosity of the solid content of the carbodiimide-modified aromatic polyisocyanate in the third isocyanate component at 25°C is, for example, 10 mPa·s or more, preferably 20 mPa·s or more, and for example, 200 mPa·s or less, preferably 100 mPa·s or less.

[0114] When the polyisocyanate component contains a third isocyanate component, the polyisocyanate component is prepared by mixing the first isocyanate component, the second isocyanate component, and the third isocyanate component. The ratio of the third isocyanate component to the polyisocyanate component is, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 17% by mass or more, and for example, 30% by mass or less, preferably 20% by mass or less, more preferably 19% by mass or less, and even more preferably 18.5% by mass or less.

[0115] Relative to 100 parts by mass of the first isocyanate component, the amount of the third isocyanate component is, for example, 10 parts by mass or more, preferably 12 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 23 parts by mass or more, and particularly preferably 25 parts by mass or more, and for example, 60 parts by mass or less, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

[0116] The polyisocyanate component preferably includes a first isocyanate component and a second isocyanate component, more preferably includes a first isocyanate component, a second isocyanate component, and a third isocyanate component. The polyisocyanate component is further preferably composed of a first isocyanate component and a second isocyanate component, and particularly preferably comprises a first isocyanate component, a second isocyanate component, and a third isocyanate component.

[0117] The polyol component contains a low-molecular-weight polyol and a high-molecular-weight polyol, and preferably consists of a low-molecular-weight polyol and a high-molecular-weight polyol.

[0118] The low molecular weight polyol may be any of the low molecular weight polyols described above as the first raw material polyol. These low molecular weight polyols may be used alone or in combination of two or more kinds.

[0119] The low-molecular-weight polyol contained in the polyol component is preferably a dihydric alcohol, more preferably an alkanediol having 2 to 6 carbon atoms (e.g., ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol), and even more preferably 1,4-butanediol.

[0120] From the viewpoint of adhesive strength, the number average molecular weight of the low molecular weight polyol is, for example, 40 or more, preferably 60 or more, more preferably 80 or more. From the viewpoint of adhesive strength, the number average molecular weight of the low molecular weight polyol is, for example, less than 200, preferably 150 or less, more preferably 100 or less.

[0121] The hydroxyl equivalent of the low-molecular-weight polyol is, for example, 20 or more, preferably 30 or more, more preferably 40 or more. The hydroxyl equivalent of the low-molecular-weight polyol is, for example, 200 or less, preferably 100 or less, more preferably 70 or less.

[0122] From the viewpoint of adhesive strength, the average number of hydroxyl groups of the low-molecular-weight polyol is, for example, 1.8 or more, preferably 1.9 or more, more preferably 2.0 or more, and from the viewpoint of adhesive strength, the average number of hydroxyl groups of the low-molecular-weight polyol is, for example, 2.5 or less, preferably 2.4 or less, more preferably 2.2 or less.

[0123] From the viewpoint of adhesive strength, the low-molecular-weight polyol is, for example, 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 12% by mass or more, relative to the polyol component, and for example, 50% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less.

[0124] The high molecular weight polyol is a compound having two or more hydroxyl groups and a number average molecular weight of 200 or more, preferably 300 or more, more preferably 400 or more, even more preferably 500 or more, particularly preferably 1000 or more, and most preferably 3000 or more, and for example, 10000 or less, preferably 7000 or less.

[0125] Examples of high molecular weight polyols include polyether polyols, polyester polyols, acid-modified polyester polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols. The high molecular weight polyol is preferably a polyether polyol, more preferably a polyoxyalkylene (carbon number 2 to 3) polyol, and even more preferably a polyoxyalkylene (carbon number 3) polyol (polyoxypropylene polyol).

[0126] The polyoxypropylene polyol preferably has its molecular terminals modified with ethylene oxide (EO) (hereinafter, sometimes referred to as EO cap). In this case, the terminal hydroxyl groups of the polyoxypropylene polyol are primary hydroxyl groups. The EO-capped polyoxypropylene polyol may have a polyoxyethylene unit modified in the middle of the polyoxypropylene chain. The polyoxypropylene polyol is more preferably a propylene oxide-ethylene oxide block copolymer.

[0127] These high molecular weight polyols can be used alone or in combination of two or more kinds.

[0128] The ethylene oxide (EO) content (ethylene oxide (EO) content) in the polyoxypropylene polyol is, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 12.5% ​​by mass or more, and for example, 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0129] From the viewpoint of adhesive strength, the number average molecular weight of the high molecular weight polyol is, for example, 1000 or more, preferably 2000 or more, more preferably 3000 or more, and even more preferably 4000 or more. From the viewpoint of adhesive strength, the number average molecular weight of the high molecular weight polyol is, for example, 10000 or less, preferably 7500 or less, and more preferably 6000 or less.

[0130] The hydroxyl equivalent of the high molecular weight polyol is, for example, 500 or more, preferably 1000 or more, more preferably 1500 or more. The hydroxyl equivalent of the high molecular weight polyol is, for example, 5000 or less, preferably 2000 or less, more preferably 1700 or less.

[0131] From the viewpoint of adhesive strength, the average number of hydroxyl groups of the high molecular weight polyol is, for example, 2.0 or more, preferably 2.5 or more, more preferably 2.8 or more, and from the viewpoint of adhesive strength, the average number of hydroxyl groups of the high molecular weight polyol is, for example, 4.0 or less, preferably 3.5 or less, more preferably 3.2 or less.

[0132] From the viewpoint of adhesive strength, the high molecular weight polyol accounts for, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and for example, 99% by mass or less, preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 90% by mass or less, relative to the polyol component.

[0133] The polyol component is prepared by mixing a low molecular weight polyol and a high molecular weight polyol.

[0134] From the viewpoint of adhesive strength, the number average molecular weight of the polyol component is, for example, 200 or more, or preferably 240 or more. From the viewpoint of adhesive strength, the number average molecular weight of the polyol component is, for example, 4000 or less, or more preferably 3500 or less.

[0135] The hydroxyl equivalent of the polyol component is, for example, 100 or more, or preferably 120 or more. The hydroxyl equivalent of the polyol component is, for example, 2000 or less, or preferably 1800 or less.

[0136] The average number of hydroxyl groups in the polyol component is, from the viewpoint of adhesive strength, for example, 2 or more, preferably 2.02 or more. Also, from the viewpoint of adhesive strength, the average number of hydroxyl groups in the polyol component is, from the viewpoint of adhesive strength, for example, 3.0 or less, preferably 2.9 or less, more preferably 2.8 or less.

[0137] The polyol component is, per 100 parts by mass of the polyisocyanate component, for example, 40 parts by mass or more, preferably 60 parts by mass or more, more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, and for example, 200 parts by mass or less, preferably 150 parts by mass or less, more preferably 125 parts by mass or less.

[0138] The polyisocyanate component and the polyol component are mixed at a predetermined equivalent ratio. Specifically, the equivalent ratio (NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component is, for example, greater than 1, preferably 1.02 or more, more preferably 1.04 or more, and for example, 2 or less, preferably 1.5 or less, more preferably 1.3 or less, even more preferably 1.2 or less, and particularly preferably 1.1 or less.

[0139] The structural polyurethane adhesive may also contain additives as needed. Examples of additives include plasticizers, fillers, compatibilizers, urethane catalysts, antioxidants, antioxidants, UV absorbers, heat stabilizers, polymeric light stabilizers, organic solvents, pigments, dyes, defoamers, dispersants, leveling agents, thixotropic agents, antiblocking agents, release agents, lubricants, interlayer modifiers, and viscosity modifiers. The content of the additives is not particularly limited and can be appropriately determined depending on the purpose and application.

[0140] The additives may be added to a mixture of the polyisocyanate component and the polyol component (for example, a one-component curing adhesive). The additives may be contained in, for example, the main agent described below, the curing agent described below, or both.

[0141] On the other hand, from the viewpoint of workability, the structural polyurethane adhesive preferably does not contain an organic solvent, that is, the structural polyurethane adhesive is preferably a solvent-free adhesive.

[0142] In the solvent-free adhesive, the polyisocyanate component is prepared, for example, without using an organic solvent, or is prepared using an organic solvent and then the solvent is removed by a known method.

[0143] In the solvent-free adhesive, the polyol component is prepared, for example, without using an organic solvent, or is prepared using an organic solvent and then the solvent is removed by a known method.

[0144] The structural polyurethane adhesive is preferably a two-component curing adhesive comprising a base agent containing a polyisocyanate component and a curing agent containing a polyol component. The two-component curing adhesive is a resin composition kit (two-component kit) that is prepared separately and then blended (mixed) at the time of use to form a cured product. That is, by mixing the base agent and curing agent, a resin mixture (polyurethane mixture) is obtained, and the resin mixture undergoes a curing reaction to obtain a cured product (cured polyurethane product). In the two-component curing adhesive, the base agent and curing agent are mixed so that the equivalent ratio of the polyisocyanate component to the polyol component is the value described above.

[0145] In the structural polyurethane adhesive, the polyisocyanate component includes a first isocyanate component and a second isocyanate component. The first isocyanate component includes a first isocyanate-terminated prepolymer, which is a reaction product of a first raw polyisocyanate made of an aromatic polyisocyanate and a first raw polyol containing polytetramethylene ether polyol. The second isocyanate component includes a second isocyanate-terminated prepolymer and / or a derivative of an aliphatic polyisocyanate, which is a reaction product of a second raw polyisocyanate containing an araliphatic polyisocyanate and / or an aliphatic polyisocyanate and a second raw polyol containing polyoxypropylene polyol. The second isocyanate component has a specific ratio to the polyisocyanate component, and the polyol component includes a low-molecular-weight polyol and a high-molecular-weight polyol. Therefore, the structural polyurethane adhesive has excellent adhesive properties.

[0146] Therefore, the structural polyurethane adhesive is suitable for use in structures made up of multiple components, such as buildings, automobiles, transportation equipment, and ships, to bond these components together.

[0147] In using a structural polyurethane adhesive, for example, a mixture containing a polyisocyanate component and a polyol component is applied to a member by a known method, cured, and optionally aged.

[0148] From the viewpoint of workability, the viscosity of the mixture containing the polyisocyanate component and the polyol component at 25°C is, for example, 100 mPa·s or more, preferably 300 mPa·s or more, and the viscosity of the mixture at 25°C is, for example, 500,000 mPa·s or less, preferably 100,000 mPa·s or less, more preferably 50,000 mPa·s or less.

[0149] The curing conditions and curing conditions are set appropriately. More specifically, the curing temperature is, for example, 10°C or higher, preferably 20°C or higher. The curing temperature is, for example, 100°C or lower, preferably 80°C or lower, and more preferably 60°C or lower. The curing time is, for example, 5 minutes or longer, preferably 10 minutes or longer. The curing time is, for example, 5 hours or shorter, preferably 2.5 hours or shorter, and more preferably 1 hour or shorter. The curing temperature is, for example, 10°C or higher, preferably 15°C or higher. The curing temperature is, for example, 80°C or lower, preferably 60°C or lower, and more preferably 40°C or lower. The curing time is, for example, 1 hour or longer, preferably 2 hours or longer. The curing time is, for example, 2 weeks or shorter, preferably 1 week or shorter.

[0150] This allows the structural polyurethane adhesive to harden and bond the components well. [Example]

[0151] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are by mass unless otherwise specified. Furthermore, specific numerical values ​​such as blending ratios (content ratios), physical property values, and parameters used in the following description can be substituted with the corresponding upper limit values ​​(numeric values ​​defined as "equal to or less than") or lower limit values ​​(numeric values ​​defined as "equal to or more than" or "exceeding") of the blending ratios (content ratios), physical property values, parameters, etc. described in the above "Form for Carrying Out the Invention."

[0152] 1. Polyisocyanate component (Preparation Example 1) First Isocyanate Component (MDI Prepolymer) (Main Component 1) As the first raw material polyol, 137.7 parts by mass of Diol-1000 (trade name, number average molecular weight 1000, polyoxypropylene glycol, manufactured by Mitsui Chemicals), 149.9 parts by mass of Takelac P-24 (trade name, number average molecular weight approximately 2000, EO-capped polyoxypropylene glycol, manufactured by Mitsui Chemicals), 107.5 parts by mass of Actocol T-1000D (trade name, number average molecular weight 1000, polyoxypropylene triol, manufactured by Mitsui Chemicals), and 207.0 parts by mass of PTG-1000 (trade name, number average molecular weight: 1000, polytetramethylene ether glycol, manufactured by Hodogaya Chemical Co., Ltd.) were mixed with 397.8 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI) as the first raw material polyisocyanate, and 0.1 parts by mass of o-toluenesulfonamide (OTSA: stabilizer). The equivalent ratio (NCO / OH) at this time was 2.8. The resulting mixture was then stirred in a nitrogen stream at 60°C for 1 hour, and then further stirred at 80°C for 4 to 12 hours to cause a urethane reaction. This resulted in the production of a first isocyanate component containing a first isocyanate group-terminated urethane prepolymer (MDI prepolymer). The solids concentration of the MDI prepolymer was 100%, the amine equivalent was 489, and the isocyanate group content was 8.6% by mass.

[0153] (Preparation Example 2) First Isocyanate Component (MDI Prepolymer) (Main Component 2) 360.3 parts by mass of PPG D-2000 (trade name, number-average molecular weight 2000, polyoxypropylene glycol, manufactured by Mitsui Chemicals, Inc.) as the first raw material polyol, and 491.1 parts by mass of Actocol EP330N (trade name, polyoxyalkylene triol (propylene oxide-ethylene oxide block copolymer), terminal oxyethylene group content 15% by mass, number-average molecular weight 5000, manufactured by Mitsui Chemicals, Inc.) as the first raw material polyol, 148.4 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI) as the first raw material polyisocyanate, and 0.2 parts by mass of OTSA were mixed. The equivalent ratio (NCO / OH) at this time was 1.8. The method was otherwise the same as in Preparation Example 1. The solids concentration of the MDI prepolymer was 100%, the amine equivalent was 1844, and the isocyanate group content was 2.3% by mass.

[0154] (Preparation Example 3) First Isocyanate Component (MDI Prepolymer) (Main Component 3) 369.9 parts by mass of Diol-1000, 99.8 parts by mass of Actocol T-700 (trade name, number average molecular weight 700, polyoxypropylene triol, manufactured by Mitsui Chemicals, Inc.), and 145.6 parts by mass of PTG-1000 were mixed as the first raw polyol material with 384.5 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI) and 0.2 parts by mass of OTSA as the first raw polyisocyanate material. The equivalent ratio (NCO / OH) was 2.1. The remaining procedures were the same as in Preparation Example 1. The solids concentration of the MDI prepolymer was 100%, the amine equivalent was 622, and the isocyanate group content was 6.8% by mass.

[0155] (Preparation Example 4) First Isocyanate Component (MDI Prepolymer) (Main Component 4) 285.3 parts by mass of PPG DL-4000 (trade name, number average molecular weight 4000, polyoxypropylene glycol, average hydroxyl value 28.1, manufactured by Mitsui Chemicals SKC Polyurethanes) and 583.1 parts by mass of Actocol T-5000 (trade name, number average molecular weight 5000, polyoxypropylene triol, manufactured by Mitsui Chemicals) as the first raw material polyol were mixed with 131.5 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI) as the first raw material polyisocyanate and 0.1 parts by mass of OTSA. The equivalent ratio (NCO / OH) at this time was 2.1. The other procedures were the same as in Preparation Example 1. The solids concentration of the MDI prepolymer was 100%, the amine equivalent was 1790, and the isocyanate group content was 2.3% by mass.

[0156] (Preparation Example 5) Second Isocyanate Component (1) (HDI / D-400) 281.3 parts by mass of Actocol D-400 (trade name, number average molecular weight 400, polyoxypropylene glycol, manufactured by Mitsui Chemicals) as the second raw material polyol, 718.5 parts by mass of hexamethylene diisocyanate (HDI) as the second raw material polyisocyanate, and 0.2 parts by mass of OTSA were mixed. The equivalent ratio (NCO / OH) at this time was 6. The resulting mixture was then stirred in a nitrogen stream at 110°C for 6 to 24 hours to cause a urethane reaction.

[0157] The resulting reaction product was then subjected to thin-film distillation (wall temperature 145 to 155°C, vacuum level 100 Pa or less, flow rate 3 to 5 g / min, cooling water temperature 10°C), thereby obtaining a second isocyanate component containing a second isocyanate group-terminated urethane prepolymer.

[0158] The solids concentration of the second isocyanate component (HDI / D-400) was 100%, the isocyanate group content was 10.7% by mass, and the content of the second raw material polyisocyanate (HDI monomer) relative to the total amount of the second isocyanate component was 0.23% by mass.

[0159] The content of the monomer was measured by HPLC.

[0160] (Preparation Example 6) Second Isocyanate Component (2) (PDI Isocyanurate-Allophanate) In a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a cooling tube, 500 parts by mass of 1,5-pentamethylene diisocyanate (PDI, trade name: STABIO PDI, manufactured by Mitsui Chemicals, Inc.), 0.25 parts by mass of 2,6-di(tert-butyl)-4-methylphenol (also known as dibutylhydroxytoluene, BHT, a hindered phenol-based antioxidant), and 0.25 parts by mass of tetraphenyl dipropylene glycol diphosphite (an organic phosphite ester, a cocatalyst) were mixed under a nitrogen atmosphere, and then 6.5 parts by mass of isobutanol was added to this mixture, and nitrogen was introduced into the liquid phase for 1 hour. The mixture was then heated to 80°C and reacted for 3 hours, after which it was cooled to 60°C. 0.2 parts by mass of trimethyl-N-2-hydroxypropylammonium 2-ethylhexanoate was added as an isocyanurate catalyst and reacted for 1.5 hours. 0.01 parts by mass of o-toluenesulfonamide was then added per 100 parts by mass of PDI. The reaction mixture was then passed through a thin-film distillation apparatus (temperature 150°C, vacuum degree 93.3 Pa) and distilled until the amount of residual PDI monomer was 1.0 mass% or less, thereby preparing an aliphatic polyisocyanate derivative (an isocyanurate-modified pentamethylene diisocyanate). The resulting aliphatic polyisocyanate derivative had an isocyanate group content of 23.2 mass%, and an average number of isocyanate functional groups of 2.8.

[0161] (Preparation Example 7) Second Isocyanate Component (3) (HDI Biuret) In a reactor equipped with a thermometer, a stirrer, a nitrogen inlet pipe, and a cooling pipe, 500 parts by mass of 1,6-hexamethylene diisocyanate (HDI, trade name: Takenate 700, manufactured by Mitsui Chemicals, Inc.), 0.3 parts by mass of tris(tridecyl)phosphite, 8 parts by mass of trimethylphosphate, and 3.57 parts by mass of water were charged under a nitrogen atmosphere, and the temperature was raised to 130°C, and the reaction was carried out until the isocyanate group content reached 44.6% by mass. The mixture was then passed through a thin-film distillation apparatus (temperature 150°C, vacuum degree 93.3 Pa) and distilled until the amount of residual HDI monomer was 0.5 mass% or less, thereby preparing an aliphatic polyisocyanate derivative (biuret-modified hexamethylene diisocyanate). The resulting aliphatic polyisocyanate derivative had an isocyanate group content of 22.8 mass%, and an average number of isocyanate functional groups of 2.8.

[0162] (Preparation Example 8) Second Isocyanate Component (4) (HDI Isocyanurate) In a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a cooling tube, 500 parts by mass of 1,6-hexamethylene diisocyanate (HDI, trade name: Takenate 700, manufactured by Mitsui Chemicals, Inc.), 0.25 parts by mass of 2,6-di(tert-butyl)-4-methylphenol (also known as dibutylhydroxytoluene, BHT, a hindered phenol-based antioxidant), and 0.25 parts by mass of tetraphenyl dipropylene glycol diphosphite (an organic phosphite ester, a cocatalyst) were mixed under a nitrogen atmosphere. 10.7 parts by mass of 1,3-butanediol was then added to this mixture, and nitrogen was introduced into the liquid phase for 1 hour. The mixture was then heated to 80°C and reacted for 3 hours, after which it was cooled to 60°C. 0.2 parts by mass of trimethyl-N-2-hydroxypropylammonium 2-ethylhexanoate was added as an isocyanurate catalyst and reacted for 1.5 hours. 0.01 parts by mass of o-toluenesulfonamide was then added per 100 parts by mass of HDI. The reaction mixture was then passed through a thin-film distillation apparatus (temperature 150°C, vacuum 93.3 Pa) and distilled until the amount of residual HDI monomer was 1.0 mass% or less, to prepare an aliphatic polyisocyanate derivative (an isocyanurate-modified hexamethylene diisocyanate). The resulting aliphatic polyisocyanate derivative had an isocyanate group content of 20.9 mass%, and an average number of isocyanate functional groups of 3.4.

[0163] (Preparation Example 9) Second Isocyanate Component (5) (XDI / D-400) 259.1 parts by mass of Actocol D-400 (trade name, number average molecular weight 400, polyoxypropylene glycol, manufactured by Mitsui Chemicals) as the second raw material polyol, 740.7 parts by mass of xylylene diisocyanate (XDI) as the second raw material polyisocyanate, and 0.2 parts by mass of OTSA were mixed. The equivalent ratio (NCO / OH) at this time was 6. The resulting mixture was then stirred in a nitrogen stream at 110°C for 6 to 24 hours to cause a urethane reaction.

[0164] The resulting reaction product was then subjected to thin-film distillation (wall temperature 145 to 155°C, vacuum level 100 Pa or less, flow rate 3 to 5 g / min, cooling water temperature 10°C), thereby obtaining a second isocyanate component containing a second isocyanate group-terminated urethane prepolymer.

[0165] The solids concentration of the second isocyanate component (XDI / D-400) was 100%, the isocyanate group content was 10.2% by mass, and the content of the second raw material polyisocyanate (XDI monomer) relative to the total amount of the second isocyanate component was 0.14% by mass.

[0166] The content of the monomer was measured by HPLC.

[0167] (Preparation Example 10) Tertiary Isocyanate Component (MDI Carbodiimide) As the third isocyanate component, Coronate MX (trade name, carbodiimide-modified diphenylmethane diisocyanate, isocyanate group content 28.9% by mass, manufactured by Tosoh Corporation) was prepared.

[0168] Examples 1 to 11 and Comparative Examples 1 to 7 The first isocyanate component, the second isocyanate component, and the third isocyanate component were mixed according to the formulations shown in Tables 1 to 3. This gave a polyisocyanate component (main component).

[0169] Additionally, Actocol EP-330N (Mitsui Chemicals, Inc.) and 1,4-butanediol (1,4-BD) were mixed according to the formulations shown in Tables 1 to 3, and a catalyst (DABCO 33-LV) was added to the mixture so that the concentration in the cured structural polyurethane adhesive was approximately 700 ppm. This resulted in a polyol component (curing agent). Actocol EP-330N is a polyoxyalkylene triol (a block copolymer of propylene oxide and ethylene oxide), with a terminal oxyethylene group content of 15% by mass and a number-average molecular weight of 5,000.

[0170] This resulted in a structural polyurethane adhesive comprising a polyisocyanate component (base) and a polyol component (curing agent).

[0171] (average number of isocyanate functional groups) The average number of isocyanate functional groups of the aliphatic polyisocyanate derivative was calculated from the isocyanate group concentration A of the aliphatic polyisocyanate derivative, the solid content concentration B (=100), and the number average molecular weight C measured by gel permeation chromatography using the following apparatus and conditions, using the following formula (1): Average number of isocyanate functional groups = A / B × C / 42.02 (1) (In the formula, A represents the isocyanate group concentration of the aliphatic polyisocyanate derivative, B represents the solid content concentration, and C represents the number average molecular weight.)

[0172] (Measurement conditions for number average molecular weight) In the GPC measurement, approximately 0.04 g of a sample was collected and dissolved in 10 mL of tetrahydrofuran. The resulting solution was then subjected to GPC measurement under the following conditions. Device: HLC-8220GPC (Tosoh Corporation) Columns: TSKgel G1000HXL, TSKgel G2000HXL, and TSKgel G3000HXL (Tosoh Corporation) connected in series. Detector: differential refractometer Injection volume: 100μL Eluent: tetrahydrofuran Flow rate: 0.8mL / min Temperature: 40℃ Calibration curve: Standard polyethylene oxide in the range of 106 to 22450 (trade name: TSK Standard Polyethylene Oxide, manufactured by Tosoh Corporation)

[0173] (evaluation) 1. Adhesion Test (Examples 1 to 11: PP / ED-SPCC) A polypropylene plate (J707G, manufactured by Prime Polymer (PP)) was cut to a width of 25 mm to prepare a test specimen. The surface of the PP was then degreased and cleaned with isopropyl alcohol, and then dried. This was subjected to a corona treatment immediately before preparation of the adhesion test specimen, and the wettability (JIS K 6768 (1999)) was adjusted to 40 dyn / cm or more, and this was designated as Adherend 1.

[0174] On the other hand, a cold-rolled steel plate (SPCC) was cut to a width of 25 mm and subjected to cationic electrodeposition coating (ED) to prepare an ED-SPCC plate (JIS G 3141 (SPCC, SD), manufactured by Test Piece). Next, the surface of the ED-SPCC was degreased and washed with isopropyl alcohol, and then dried. This was used as adherend 2.

[0175] Then, the polyisocyanate component and the polyol component were mixed in such a ratio that the equivalent ratio (NCO / OH) was 1.05.

[0176] The mixture was then applied to adherend 1, and adherend 1 and adherend 2 were brought into close contact so that the adhesive area was 25 mm x 12.5 mm and the adhesive layer thickness was 0.3 mm. The mixture was cured for 20 minutes at room temperature (19-27°C, 40-60% RH (relative humidity)) and then aged at room temperature for one week. Glass beads (ASGB-60, AS ONE, 0.250-0.355 mm) were placed in an appropriate amount (several dozen beads) on the adhesive surface (the surface after the mixture was applied to adherend 1) to adjust the layer thickness. This resulted in an adhesion test specimen (hereinafter referred to as test plate).

[0177] The shear adhesive strength (hereinafter referred to as adhesive strength) [MPa] between adherend 1 and adherend 2 was measured using a tensile tester (U-4410, manufactured by Orientec Co., Ltd.) at a tensile speed of 50 mm / min.

[0178] 2. Adhesion Test (Examples 1 to 11, Comparative Examples 1 to 7: ABS / ED-SPCC) An acrylonitrile butadiene styrene (ABS) resin plate (manufactured by Test Piece Co., Ltd.) was used as the adherend 1, and an adhesion test similar to the adhesion test (PP / ED-SPCC) was carried out, except that no corona treatment was performed.

[0179] 3. Adhesion Test (Examples 1 to 11: PC / ED-SPCC) A polycarbonate (PC) resin plate (manufactured by Test Piece Co., Ltd.) was used as the adherend 1, and an adhesion test similar to the adhesion test (PP / ED-SPCC) was carried out, except that no corona treatment was carried out.

[0180] 4. Adhesion Test (Examples 1 to 11: (PC / ABS Alloy) / ED-SPCC) A PC / ABS alloy plate (Sumitomo Bakelite Lower EFN800-04 (black), manufactured by Test Piece Co., Ltd.) was used as the adherend 1, and an adhesion test similar to the adhesion test (PP / ED-SPCC) was carried out, except that no corona treatment was performed.

[0181] [Table 1]

[0182] [Table 2]

[0183] [Table 3]

[0184] In Comparative Examples 3 and 7, cohesive failure occurred but the adhesive strength was low, and in Comparative Examples 1, 2, and 4 to 6, although some had high adhesive strength, all experienced interfacial peeling, whereas in the Examples, all experienced cohesive failure and also had high adhesive strength.

Claims

1. Contains a polyisocyanate component and a polyol component, the polyisocyanate component includes a first isocyanate component and a second isocyanate component; the first isocyanate component comprises a first isocyanate group-terminated prepolymer; The first isocyanate group-terminated prepolymer is a reaction product of a first raw material polyisocyanate comprising an aromatic polyisocyanate and a first raw material polyol comprising a polytetramethylene ether polyol; the second isocyanate component is a second isocyanate-terminated prepolymer and / or a derivative of an aliphatic polyisocyanate; The second isocyanate group-terminated prepolymer is a reaction product of a second raw material polyisocyanate containing an araliphatic polyisocyanate and / or an aliphatic polyisocyanate and a second raw material polyol containing a polyoxypropylene polyol; the second isocyanate component is It is 3% by mass or more and 25% by mass or less based on the polyisocyanate component, The polyol component is Contains a low-molecular-weight polyol having a number-average molecular weight of less than 200 and a high-molecular-weight polyol having a number-average molecular weight of 200 or more, The first raw material polyol further comprises: a polyoxypropylene polyol having an average number of hydroxyl groups of 2; and a polyoxypropylene polyol having an average number of 3 hydroxyl groups. Structural polyurethane adhesive.

2. A structural polyurethane adhesive as described in claim 1, wherein the first raw material polyol includes a polyoxypropylene polyol whose terminal hydroxyl groups are primary hydroxyl groups.

3. the polyisocyanate component further comprises a third isocyanate component; 3. The structural polyurethane adhesive according to claim 1, wherein the third isocyanate component is a carbodiimide-modified aromatic polyisocyanate.

4. The aliphatic polyisocyanate derivative is at least one selected from the group consisting of an isocyanurate-modified aliphatic polyisocyanate, an allophanate-modified aliphatic polyisocyanate, an isocyanurate-allophanate-modified aliphatic polyisocyanate, and a biuret-modified aliphatic polyisocyanate; The structural polyurethane adhesive according to any one of claims 1 to 3.

5. The structural polyurethane adhesive according to any one of claims 1 to 4, wherein the polytetramethylene ether polyol is present in an amount of 5% by mass or more and 50% by mass or less relative to the total amount of the first raw material polyol.

6. The high molecular weight polyol of the polyol component is Contains polyoxypropylene polyol, The structural polyurethane adhesive according to any one of claims 1 to 5, wherein the terminal hydroxyl groups of the polyoxypropylene polyol contained in the high molecular weight polyol are primary hydroxyl groups.

7. The structural polyurethane adhesive according to any one of claims 1 to 6, which is a two-component curing adhesive comprising a base agent containing the polyisocyanate component and a curing agent containing the polyol component.

8. The structural polyurethane adhesive according to any one of claims 1 to 7, which is a solvent-free adhesive.

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