Structural polyurethane adhesive

Abstract

To provide a structural polyurethane adhesive which offers superior adhesive properties while utilizing plant-derived raw materials.SOLUTION: A structural polyurethane adhesive comprises a polyisocyanate component and a polyol component. The polyisocyanate component comprises a first isocyanate component and a second isocyanate component. The first isocyanate component contains a first isocyanate group-terminated prepolymer, and the second isocyanate component contains a derivative of an aliphatic polyisocyanate. The polyol component comprises a high molecular weight polyol and a low molecular weight polyol. The high molecular weight polyol is a vegetable oil polyol and has a hydroxyl value of 200 mgKOH / g or more. The content of the high molecular weight polyol is 89 mass% or more and 99 mass% or less relative to the total amount of the polyol component.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In the past, structural adhesives have been used to bond multiple components in structures. For example, a two-component curing structural polyurethane adhesive containing a base agent (component 1) and a curing agent (component 2) is known as a structural adhesive.

[0003] More specifically, the following formulation has been proposed as a structural polyurethane adhesive. That is, the curing agent (component 1) contains polypropylene glycol and 1,4-butanediol. The base agent (component 2) contains an isocyanate-terminated urethane prepolymer and an aliphatic polyisocyanate derivative (an isocyanurate-modified product of hexamethylene diisocyanate). The isocyanate-terminated urethane prepolymer contains a reaction product of 4,4'-methylenediphenyl diisocyanate (MDI) as a polyisocyanate and polyoxypropylene glycol, polyoxypropylene triol, and polytetramethylene ether glycol as a polyol (see, for example, Patent Document 1 (Example 5)). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-132199 A Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in light of the increasing demand to reduce petroleum-derived carbon dioxide (CO2) emissions with the aim of achieving carbon neutrality, structural polyurethane adhesives are required to have excellent adhesive properties while using raw materials derived from plants.

[0006] The present invention provides a structural polyurethane adhesive that uses raw materials derived from plants and has excellent adhesive properties. [Means for solving the problem]

[0007] The present invention [1] includes a structural polyurethane adhesive comprising a polyisocyanate component and a polyol component, the polyisocyanate component comprising a first isocyanate component and a second isocyanate component, the first isocyanate component comprising a first isocyanate group-terminated prepolymer, the second isocyanate component comprising a derivative of an aliphatic polyisocyanate, the polyol component comprising a high molecular weight polyol and a low molecular weight polyol, the high molecular weight polyol being a vegetable oil polyol, the high molecular weight polyol having a hydroxyl value of 200 mgKOH / g or more, and a content of the high molecular weight polyol relative to the total amount of the polyol component of 89 mass% or more and 99 mass% or less.

[0008] The present invention [2] comprises the structural polyurethane adhesive described in [1] above, in which 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 is an aromatic polyisocyanate, and the first raw material polyol contains polytetramethylene ether glycol and / or vegetable oil polyol containing a plant-derived component.

[0009] The present invention [3] includes the structural polyurethane adhesive according to [1] or [2] above, in which the content of isocyanate groups in the first isocyanate component is 9.0 mass% or more.

[0010] The present invention [4] includes a structural polyurethane adhesive according to any one of the above [1] to [3], wherein the derivative of the aliphatic polyisocyanate includes an isocyanurate-modified aliphatic polyisocyanate and / or an adduct-modified aliphatic polyisocyanate.

[0011] The present invention [5] comprises the structural polyurethane adhesive according to any one of the above [1] to [4], 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] includes a structural polyurethane adhesive according to any one of the above [1] to [5], in which the content of the high molecular weight polyol relative to the total amount of the polyol component is 96 mass % or less.

[0013] The present invention [7] comprises the structural polyurethane adhesive according to any one of the above [1] to [6], wherein the content of isocyanate groups in the polyisocyanate component is 10.0 mass % or more.

[0014] The present invention [8] includes the structural polyurethane adhesive according to any one of the above [1] to [7], in which the high molecular weight polyol is castor oil polyol.

[0015] The present invention [9] comprises the structural polyurethane adhesive according to any one of the above [1] to [8], wherein the high molecular weight polyol has a hydroxyl value of 250 mg KOH / g or more.

[0016] The present invention

[10] includes a structural polyurethane adhesive according to any one of the above [1] to [9], wherein the content of plant-derived components in the structural polyurethane adhesive is 20% by mass or more and 80% by mass or less.

[0017] The present invention

[11] includes the structural polyurethane adhesive according to any one of the above [1] to

[10] , which is a two-component curing adhesive comprising a base agent containing the polyisocyanate component and a curing agent containing the polyol component.

[0018] The present invention

[12] comprises the structural polyurethane adhesive according to any one of the above [1] to

[11] , which is a solvent-free adhesive. Effect of the Invention

[0019] The structural polyurethane adhesive of the present invention contains 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-terminated prepolymer, the second isocyanate component contains a derivative of an aliphatic polyisocyanate, the polyol component contains a high molecular weight polyol and a low molecular weight polyol, the high molecular weight polyol is a vegetable oil polyol, the hydroxyl value of the high molecular weight polyol is 200 mgKOH / g or more, and the content of the high molecular weight polyol relative to the total amount of the polyol component is 89 mass% or more and 99 mass% or less. Therefore, the adhesive has excellent adhesive properties while using raw materials derived from plants. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 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 a large load for a long period of time."

[0021] More specifically, the structural polyurethane adhesive contains, as essential components, a polyisocyanate component and a polyol component. The polyisocyanate component is a component that contains a free isocyanate group. The polyol component is a component that contains a free hydroxyl group.

[0022] The structural polyurethane adhesive may be a one-component curing adhesive in which a polyisocyanate component and a polyol component are mixed in advance. Alternatively, the structural polyurethane adhesive may be a two-component curing adhesive comprising a base agent (liquid A) containing a polyisocyanate component and a curing agent (liquid B) containing a polyol component. In the two-component curing adhesive, the base agent and the 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.

[0023] <Polyisocyanate component> The polyisocyanate component includes a first isocyanate component and a second isocyanate component, and optionally further includes a third isocyanate component.

[0024] [First 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), and preferably consists of a first isocyanate group-terminated prepolymer.

[0025] Specifically, the first isocyanate component includes a first isocyanate group-terminated prepolymer. The first isocyanate group-terminated prepolymer is, for example, 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 are reacted so that the isocyanate groups are in excess relative to the hydroxyl groups.

[0026] Examples of the first raw material polyisocyanate include aromatic polyisocyanates. Examples of the aromatic polyisocyanate include aromatic polyisocyanate monomers and aromatic polyisocyanate derivatives.

[0027] Examples of aromatic polyisocyanate monomers include aromatic diisocyanates. Examples of aromatic diisocyanates include tolylene diisocyanate, phenylene diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate, toluidine diisocyanate, and diphenyl ether diisocyanate. The aromatic diisocyanates can be used alone or in combination of two or more kinds.

[0028] The aromatic polyisocyanate derivative may be a modified product obtained by modifying the aromatic polyisocyanate monomer by a known method.Specifically, the aromatic polyisocyanate derivative may be a uretdione modified product, an isocyanurate modified product, an allophanate modified product, a polyol modified product, a biuret modified product, a urea modified product, an oxadiazinetrione modified product, or a carbodiimide modified product.The aromatic polyisocyanate derivative may also be a polymethylene polyphenylene polyisocyanate.The aromatic polyisocyanate derivative may be used alone or in combination of two or more kinds.

[0029] The aromatic polyisocyanates can be used alone or in combination of two or more kinds.

[0030] 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.

[0031] In other words, from the viewpoint of adhesive properties, the first raw material polyisocyanate is preferably an aromatic polyisocyanate, more preferably an aromatic polyisocyanate monomer, even more preferably an aromatic diisocyanate, and particularly preferably diphenylmethane diisocyanate.

[0032] The first raw material polyol contains a high molecular weight polyol (first high molecular weight polyol) as an essential component. The first high molecular weight polyol is a relatively high molecular weight organic compound having two or more hydroxyl groups. The number average molecular weight (or molecular weight) of the first high molecular weight polyol is, for example, 200 to 10,000, preferably 300 to 10,000, more preferably 400 to 7,000, and further preferably 500 to 7,000.

[0033] The first high molecular weight polyol is not particularly limited, but examples thereof include polyether polyol, polyester polyol, polycarbonate polyol, polyurethane polyol, epoxy polyol, vegetable oil polyol, polyolefin polyol, acrylic polyol, and vinyl monomer modified polyol, preferably polyether polyol, polyester polyol, polycarbonate polyol, and vegetable oil polyol, more preferably polyether polyol and vegetable oil polyol. The first high molecular weight polyol can be used alone or in combination of two or more kinds.

[0034] Examples of polyether polyols include polytetramethylene ether polyols and polyoxyalkylene (C2-3) polyols. The polyether polyols can be used alone or in combination of two or more kinds, preferably, polytetramethylene ether polyols can be used alone, and polytetramethylene ether polyols and polyoxyalkylene (C2-3) polyols can be used in combination, more preferably, polytetramethylene ether polyols and polyoxyalkylene (C2-3) polyols can be used in combination.

[0035] Examples of polytetramethylene ether polyols include ring-opening polymers (polytetramethylene ether glycol (crystalline)) obtained by cationic polymerization of tetrahydrofuran, and amorphous (non-crystalline) polytetramethylene ether glycols obtained by copolymerizing alkyl-substituted tetrahydrofuran or dihydric alcohols (described later) with polymerization units of tetrahydrofuran, etc. Here, the term "amorphous" refers to a liquid at room temperature (25°C), and the term "crystalline" refers to a solid at room temperature (25°C).

[0036] In addition, as the polytetramethylene ether polyol, from the viewpoint of increasing demand for reducing petroleum-derived carbon dioxide (CO2) emissions for the purpose of carbon neutrality, a preferable example is a polytetramethylene ether polyol containing a plant-derived component. Note that the polytetramethylene ether polyol containing a plant-derived component is a polytetramethylene ether polyol using a plant-derived raw material.

[0037] Specifically, examples of polytetramethylene ether polyols containing plant-derived components include polytetramethylene ether glycols obtained by ring-opening polymerization of tetrahydrofuran using furfural derived from plant-derived raw materials such as corn.

[0038] The polytetramethylene ether polyol containing a plant-derived component may be a commercially available product, such as BioPTMG650 (trade name, polytetramethylene ether glycol, number average molecular weight: 650, hydroxyl value: 174 mgKOH / g, manufactured by Mitsubishi Chemical Corporation) or BioPTMG1000 (trade name, polytetramethylene ether glycol, number average molecular weight: 1000, hydroxyl value: 114 mgKOH / g, manufactured by Mitsubishi Chemical Corporation).

[0039] The number average molecular weight of the polytetramethylene ether polyol is, for example, 200 to 10,000, preferably 300 to 8,000, more preferably 300 to 5,000, still more preferably 300 to 2,000, and particularly preferably 500 to 1,500. The number average molecular weight is a polystyrene-equivalent molecular weight measured by gel permeation chromatography (the same applies hereinafter).

[0040] The hydroxyl value (OH value) of the polytetramethylene ether polyol is, for example, 50 mgKOH / g to 500 mgKOH / g, preferably 80 mgKOH / g to 400 mgKOH / g, more preferably 90 mgKOH / g to 300 mgKOH / g, still more preferably 100 mgKOH / g to 200 mgKOH / g, and particularly preferably 105 mgKOH / g to 190 mgKOH / g.

[0041] The hydroxyl value (OH value) of the polytetramethylene ether polyol is, for example, 50 mgKOH / g or more, preferably 80 mgKOH / g or more, more preferably 90 mgKOH / g or more, even more preferably 100 mgKOH / g or more, particularly preferably 105 mgKOH / g or more, and for example, 500 mgKOH / g or less, preferably 400 mgKOH / g or less, more preferably 300 mgKOH / g or less, even more preferably 200 mgKOH / g or less, particularly preferably 190 mgKOH / g or less.

[0042] The hydroxyl equivalent can be calculated from the hydroxyl value (the same applies below).

[0043] The average number of hydroxyl groups in the polytetramethylene ether polyol is, for example, 1.6 to 3.5, preferably 1.7 to 3.0, more preferably 1.8 to 2.5, and still more preferably 1.8 to 2.2.

[0044] The average number of hydroxyl groups of the polytetramethylene ether polyol is, for example, 1.6 or more, preferably 1.7 or more, more preferably 1.8 or more, and for example, 3.5 or less, preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.2 or less.

[0045] The hydroxyl value and hydroxyl equivalent can be measured, for example, according to 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. In addition, the hydroxyl value, hydroxyl equivalent, and average number of hydroxyl groups can also be calculated from the charging ratio of the raw material components (same below).

[0046] Examples of polyoxyalkylene (C2-3) polyols include polyoxyethylene polyols, polyoxypropylene polyols, polyoxytriethylene polyols, and polyoxyethylene-polyoxypropylene polyols (random or block copolymers), and preferably polyoxypropylene polyols. The polyoxyalkylene (C2-3) polyols can be used alone or in combination of two or more kinds.

[0047] Examples of polyoxypropylene polyols include polyoxypropylene polyols having an average number of hydroxyl groups of 2 and polyoxypropylene polyols having an average number of hydroxyl groups of 3. The polyoxypropylene polyols can be used alone or in combination of two or more kinds.

[0048] The polyoxypropylene polyol having an average number of 2 hydroxyl groups has a number average molecular weight of, for example, 200 to 10,000, preferably 300 to 5,000, more preferably 500 to 3,000, and still more preferably 750 to 2,500.

[0049] The hydroxyl value (OH value) of the polyoxypropylene polyol having an average number of hydroxyl groups of 2 is, for example, 50 mgKOH / g to 400 mgKOH / g, preferably 80 mgKOH / g to 300 mgKOH / g, more preferably 90 mgKOH / g to 200 mgKOH / g, and still more preferably 100 mgKOH / g to 150 mgKOH / g.

[0050] The hydroxyl value (OH value) of the polyoxypropylene polyol having an average number of 2 hydroxyl groups is, for example, 50 mgKOH / g or more, preferably 80 mgKOH / g or more, more preferably 90 mgKOH / g or more, even more preferably 100 mgKOH / g or more, and for example, 400 mgKOH / g or less, preferably 300 mgKOH / g or less, more preferably 200 mgKOH / g or less, even more preferably 150 mgKOH / g or less.

[0051] The polyoxypropylene polyol having an average number of 3 hydroxyl groups has a number average molecular weight of, for example, 200 to 10,000, preferably 300 to 5,000, more preferably 500 to 3,000, and still more preferably 750 to 2,000.

[0052] The hydroxyl value (OH value) of the polyoxypropylene polyol having an average number of 3 hydroxyl groups is, for example, 50 mgKOH / g to 500 mgKOH / g, preferably 80 mgKOH / g to 400 mgKOH / g, more preferably 100 mgKOH / g to 300 mgKOH / g, still more preferably 120 mgKOH / g to 200 mgKOH / g, and particularly preferably 130 mgKOH / g to 180 mgKOH / g.

[0053] The hydroxyl value (OH value) of the polyoxypropylene polyol having an average number of 3 hydroxyl groups is, for example, 50 mgKOH / g or more, preferably 80 mgKOH / g or more, more preferably 100 mgKOH / g or more, even more preferably 120 mgKOH / g or more, particularly preferably 130 mgKOH / g or more, and for example, 500 mgKOH / g or less, preferably 400 mgKOH / g or less, more preferably 300 mgKOH / g or less, even more preferably 200 mgKOH / g or less, particularly preferably 180 mgKOH / g or less.

[0054] The molecular terminal of the polyoxypropylene polyol may be modified with ethylene oxide (EO) (hereinafter, sometimes referred to as EO cap). In that case, the terminal hydroxyl group of the polyoxypropylene polyol is a primary hydroxyl group. The EO-capped polyoxypropylene polyol may be modified with a polyoxyethylene unit in the middle of the polyoxypropylene chain.

[0055] In addition, in view of the increasing demand for reducing petroleum-derived carbon dioxide (CO2) emissions with the aim of achieving carbon neutrality, the polyoxyalkylene (C2-3) polyol may be a polyoxyalkylene (C2-3) polyol containing a plant-derived component. The plant-derived polyoxyalkylene (C2-3) polyol is a polyoxyalkylene (C2-3) polyol that uses a plant-derived raw material.

[0056] Specifically, examples of polyoxyalkylene (C2-3) polyols containing plant-derived components include polyalkylene (C2-3) polyols containing plant-derived components obtained using a low-molecular-weight polyol containing a plant-derived component as an initiator. The low-molecular-weight polyol containing a plant-derived component is a low-molecular-weight polyol using a plant-derived raw material, and has a molecular weight of less than 200, preferably 180 or less. Examples of such low-molecular-weight polyols include 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, isosorbide, and glycerin.

[0057] When a polytetramethylene ether polyol containing a plant-derived component and a polyoxypropylene polyol are used in combination, the mixing ratio of the polyoxypropylene polyol relative to 100 parts by mass of the polytetramethylene ether polyol containing a plant-derived component is, for example, 0.1 parts by mass to 500 parts by mass, preferably 1.0 parts by mass to 300 parts by mass, more preferably 3.0 parts by mass to 200 parts by mass, even more preferably 4.0 parts by mass to 100 parts by mass, particularly preferably 5.0 parts by mass to 50 parts by mass, and most preferably 5.0 parts by mass to 10 parts by mass.

[0058] When a polytetramethylene ether polyol containing a plant-derived component and a polyoxypropylene polyol are used in combination, the mixing ratio of the polyoxypropylene polyol to 100 parts by mass of the polytetramethylene ether polyol containing a plant-derived component is, for example, 0.1 part by mass or more, preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, even more preferably 4.0 parts by mass or more, particularly preferably 5.0 parts by mass or more, and for example, 500 parts by mass or less, preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 100 parts by mass or less, particularly preferably 50 parts by mass or less, and most preferably 10 parts by mass or less.

[0059] Examples of the vegetable oil polyol include polyols containing vegetable oil and fatty acids derived from plants, and preferably vegetable oil.

[0060] Examples of the vegetable oil include castor oil, soybean oil, palm oil, sesame oil, rapeseed oil, coconut oil, and hydrogenated products thereof, and preferably castor oil. The vegetable oils can be used alone or in combination of two or more kinds.

[0061] Examples of polyols containing plant-derived fatty acids include polyester polyols obtained by condensation reaction of plant-derived fatty acids using a low molecular weight polyol (described later) as an initiator, ester-modified polyols obtained by reaction of plant-derived fatty acids with polyoxypropylene polyols, and polyester polyols obtained by condensation reaction of plant-derived fatty acids with vegetable oils.

[0062] The fatty acid derived from a plant is a fatty acid obtained from a plant raw material (including the above-mentioned vegetable oil), and can be obtained, for example, by hydrolyzing the above-mentioned vegetable oil. The vegetable oil may be a hydrogenated product thereof (i.e., a hardened vegetable oil). In other words, the fatty acid derived from a plant may be a hydrogenated product thereof (i.e., a hardened fatty acid).

[0063] The method for hydrolyzing the vegetable oil is not particularly limited, and any known method can be used.

[0064] In addition, the fatty acid derived from a plant preferably contains a fatty acid containing a hydroxyl group (hereinafter referred to as a hydroxyl-containing fatty acid). When the fatty acid derived from a plant does not contain a hydroxyl-containing fatty acid, after hydrolysis of the vegetable oil, a hydroxyl group can be added to the obtained unsaturated fatty acid by a method such as air oxidation, epoxidation, or hydroformylation to obtain a hydroxyl-containing fatty acid.

[0065] Examples of hydroxyl-containing fatty acids include hydroxyl-containing monocarboxylic acids such as ricinoleic acid, 12-hydroxystearic acid, and lactic acid, and hydroxyl-containing dicarboxylic acids such as malic acid, preferably hydroxyl-containing monocarboxylic acids, more preferably ricinoleic acid. Hydroxyl-containing fatty acids can be used alone or in combination of two or more kinds. The hydroxyl-containing fatty acids contained in the plant-derived fatty acids are appropriately selected according to the type of vegetable oil used.

[0066] In the following description, castor oil and polyols containing fatty acids derived from castor oil (including hydrogenated castor oil) are referred to as castor oil polyols. That is, castor oil polyols are polyols containing castor oil and fatty acids derived from castor oil. Note that the fatty acids derived from castor oil are fatty acids obtained from castor oil, and can be obtained, for example, by hydrolyzing castor oil.

[0067] Examples of polyols containing fatty acids derived from castor oil include ester-modified castor oil polyols obtained by reacting castor oil fatty acids with polyoxypropylene polyols, castor oil polyester polyols obtained by condensation reaction of hydroxycarboxylic acids such as castor oil fatty acids or hydrogenated castor oil fatty acids using a low molecular weight polyol (described later) as an initiator, and castor oil polyester polyols obtained by condensation reaction of hydroxycarboxylic acids such as castor oil fatty acids or hydrogenated castor oil fatty acids with castor oil.

[0068] Fatty acids derived from castor oil contain, as the main component, ricinoleic acid, a hydroxyl-containing fatty acid.

[0069] In addition, the fatty acids derived from castor oil contain, as fatty acids other than ricinoleic acid, unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid, and saturated fatty acids such as palmitic acid and stearic acid.

[0070] The content of each fatty acid in the fatty acids derived from castor oil is, for example, 87% by mass to 90% by mass of ricinoleic acid, 2.5% by mass to 4% by mass of oleic acid, 4% by mass to 5% by mass of linoleic acid, 0.5% by mass to 1.5% by mass of linolenic acid, 0.5% by mass to 1.5% by mass of palmitic acid, and 0.5% by mass to 1.5% by mass of stearic acid, relative to the total amount of the fatty acids derived from castor oil.

[0071] Furthermore, when hydrogenated castor oil is used as the vegetable oil, the hydrogenated castor oil fatty acid obtained by hydrolysis thereof contains 12-hydroxystearic acid, which is a hydroxyl group-containing fatty acid, as the main component.

[0072] The vegetable oil polyol has a number average molecular weight (or molecular weight) of, for example, 200 to 10,000, preferably 300 to 5,000, more preferably 500 to 3,000, and still more preferably 750 to 2,500.

[0073] The hydroxyl value (OH value) of the vegetable oil polyol is, for example, 50 mgKOH / g to 500 mgKOH / g, preferably 80 mgKOH / g to 400 mgKOH / g, more preferably 100 mgKOH / g to 300 mgKOH / g, still more preferably 130 mgKOH / g to 250 mgKOH / g, and particularly preferably 150 mgKOH / g to 200 mgKOH / g.

[0074] The hydroxyl value (OH value) of the vegetable oil polyol is, for example, 50 mgKOH / g or more, preferably 80 mgKOH / g or more, more preferably 100 mgKOH / g or more, even more preferably 130 mgKOH / g or more, particularly preferably 150 mgKOH / g or more, and for example, 500 mgKOH / g or less, preferably 400 mgKOH / g or less, more preferably 300 mgKOH / g or less, even more preferably 250 mgKOH / g or less, particularly preferably 200 mgKOH / g or less.

[0075] The average number of hydroxyl groups of the vegetable oil polyol is, for example, 1.6 to 3.5, preferably 1.7 to 3.0, more preferably 1.8 to 2.5, and still more preferably 1.8 to 2.2.

[0076] The average number of hydroxyl groups of the vegetable oil polyol is, for example, 1.6 or more, preferably 1.7 or more, more preferably 1.8 or more, and for example, 3.5 or less, preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.2 or less.

[0077] From the viewpoint of increasing demand for reducing petroleum-derived carbon dioxide (CO2) emissions for the purpose of carbon neutrality, the first raw material polyol preferably contains a plant-derived polyol. More preferably, the first raw material polyol contains a polytetramethylene ether polyol containing a plant-derived component and / or a vegetable oil polyol. Specifically, examples of the first raw material polyol include a single use of a polytetramethylene ether polyol containing a plant-derived component, a single use of a castor oil polyol, and a combination of a polytetramethylene ether polyol containing a plant-derived component and a polyoxypropylene polyol, and preferably a combination of a polytetramethylene ether polyol containing a plant-derived component and a polyoxypropylene polyol.

[0078] The content ratio of polytetramethylene ether polyol containing a plant-derived component and vegetable oil polyol relative to the total amount of the first raw material polyol is, for example, 20% by mass to 100% by mass, preferably 30% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, even more preferably 70% by mass to 100% by mass, and particularly preferably 90% by mass to 95% by mass.

[0079] The content ratio of polytetramethylene ether polyol and vegetable oil polyol containing plant-derived components relative to the total amount of the first raw material polyol is, for example, 20 mass% or more, preferably 30 mass% or more, more preferably 50 mass% or more, even more preferably 70 mass% or more, particularly preferably 90 mass% or more, and for example, 100 mass% or less, preferably 95 mass% or less.

[0080] If the content ratio of the polytetramethylene ether polyol containing plant-derived components and the vegetable oil polyol to the total amount of the first raw material polyol is equal to or higher than the above lower limit, the biomass degree (described later) can be sufficiently ensured. Also, if the content ratio of the polytetramethylene ether polyol containing plant-derived components and the vegetable oil polyol is equal to or lower than the above upper limit, the adhesive strength is excellent.

[0081] The first raw material polyol may contain a low molecular weight polyol as an optional component. The low molecular weight polyol in the first raw material polyol (hereinafter referred to as the first low molecular weight polyol) is a relatively low molecular weight organic compound having two or more hydroxyl groups. The molecular weight of the first low molecular weight polyol is less than 200, preferably 180 or less.

[0082] Examples of the first low molecular weight polyol include dihydric alcohols, trihydric alcohols, and tetrahydric or higher alcohols. Examples of the 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 the trihydric alcohols include glycerin and trimethylolpropane. Examples of the tetrahydric or higher alcohols include pentaerythritol and diglycerin. The first low molecular weight polyols can be used alone or in combination of two or more kinds.

[0083] The content ratio 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 ratio of the first low molecular weight polyol relative to 100 parts by mass of the total amount of the first raw material 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. 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 the first high molecular weight polyol.

[0084] 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.

[0085] 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, 1.0 to 10.0, preferably 1.5 to 10.0, more preferably 2.0 to 5.0, even more preferably 2.5 to 4.0, particularly preferably 2.8 to 3.5, and most preferably 3.0 to 3.3.

[0086] 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, 1.0 or more, preferably 1.5 or more, more preferably 2.0 or more, even more preferably 2.5 or more, particularly preferably 2.8 or more, and most preferably 3.0 or more, and for example, 10.0 or less, preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.3 or less.

[0087] In the urethanization reaction, a known polymerization method is adopted. Examples of the polymerization method include bulk polymerization and solution polymerization. In the bulk polymerization, for example, the above components are mixed and reacted under a nitrogen atmosphere. In the 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 to 120°C, preferably 50°C to 100°C. The reaction time is, for example, 0.5 hours to 24 hours, preferably 1 hour to 15 hours. In the solution polymerization, the mixing ratio of the organic solvent is appropriately set depending on the purpose and application. In the urethanization reaction, preferably, bulk polymerization (solventless reaction) is adopted.

[0088] In the urethane reaction, a known urethane catalyst is added as necessary. In addition, unreacted polyisocyanate is removed by a known method as necessary. This produces a first isocyanate component containing a first isocyanate group-terminated prepolymer.

[0089] Examples of the first isocyanate-terminated prepolymer include a first isocyanate-terminated prepolymer that is a reaction product of an aromatic polyisocyanate with a polytetramethylene ether polyol and a polyoxypropylene polyol that contain a plant-derived component, and examples of the first isocyanate-terminated prepolymer that is a reaction product of an aromatic polyisocyanate with a polytetramethylene ether polyol that contains a plant-derived component, and examples of the first isocyanate-terminated prepolymer that is a reaction product of an aromatic polyisocyanate with a castor oil polyol. Examples of the first isocyanate-terminated prepolymer include a first isocyanate-terminated prepolymer that is a reaction product of an aromatic polyisocyanate with a polytetramethylene ether polyol and a polyoxypropylene polyol that contain a plant-derived component. More preferably, the first isocyanate group-terminated prepolymer is a reaction product of diphenylmethane dipolyisocyanate with polytetramethylene ether polyol and polyoxypropylene polyol containing a plant-derived component.

[0090] In addition, the first isocyanate component may contain free (unreacted) first raw material polyisocyanate, organic solvent, and urethane catalyst as necessary. In addition, the free (unreacted) first raw material polyisocyanate, organic solvent, and urethane catalyst may be removed by a known removal means. Examples of the removal means include extraction and distillation.

[0091] The content ratio of free (unreacted) first raw material polyisocyanate relative to the total amount of the first isocyanate component is, from the viewpoint of adhesive properties, for example, 35 mass % or less, preferably 30 mass % or less, relative to the total amount of the polyisocyanate component.

[0092] The content ratio of the first isocyanate group-terminated prepolymer relative to the total amount of the first isocyanate component is, for example, 65 mass % or more, or preferably 70 mass % or more.

[0093] When the content ratio of the first isocyanate group-terminated prepolymer to the total amount of the first isocyanate component is equal to or higher than the above lower limit, the adhesive properties are excellent. Note that, when the content ratio of the free (unreacted) first raw material polyisocyanate to the total amount of the first isocyanate component is equal to or lower than the above upper limit, the content of the first isocyanate group-terminated prepolymer can be secured, and therefore the adhesive properties are excellent.

[0094] The average number of isocyanate groups in the first isocyanate component (solid content) is, for example, 2.0 to 4.0, preferably 2.0 to 3.0, and more preferably 2.1 to 2.8.

[0095] The average number of isocyanate groups in the first isocyanate component (solid content) is, for example, 2.0 or more, preferably 2.1 or more, and for example, 4.0 or less, preferably 3.0 or less, more preferably 2.8 or less.

[0096] The first isocyanate component (solid content) has an isocyanate group equivalent of, for example, 100 to 2000, preferably 200 to 1000, more preferably 250 to 500, further preferably 300 to 450, and particularly preferably 300 to 400.

[0097] The isocyanate group equivalent of the first isocyanate component (solid content) is, for example, 100 or more, preferably 200 or more, more preferably 250 or more, even more preferably 300 or more, and for example, 2000 or less, preferably 1000 or less, more preferably 500 or less, even more preferably 450 or less, and particularly preferably 400 or less.

[0098] The isocyanate group equivalent can be determined by JIS K 1603-1 (2007) Method A or B. The isocyanate group equivalent is synonymous with the amine equivalent.

[0099] The content of isocyanate groups in the first isocyanate component (solid content) (isocyanate group content (NCO%)) is, for example, 3.0 mass% to 20.0 mass%, preferably 5.0 mass% to 18.0 mass%, more preferably 7.0 mass% to 16.0 mass%, even more preferably 8.5 mass% to 15.0 mass%, particularly preferably 9.0 mass% to 14.0 mass%, and most preferably 11.0 mass% to 13.5 mass%.

[0100] The isocyanate group content (isocyanate group content (NCO%)) of the first isocyanate component (solid content) is, for example, 3.0 mass% or more, preferably 5.0 mass% or more, more preferably 7.0 mass% or more, even more preferably 8.5 mass% or more, particularly preferably 9.0 mass% or more, and most preferably 11.0 mass% or more.

[0101] The isocyanate group content (isocyanate group content (NCO%)) of the first isocyanate component (solid content) is, for example, 20.0 mass% or less, preferably 18.0 mass% or less, more preferably 16.0 mass% or less, even more preferably 15.0 mass% or less, particularly preferably 14.0 mass% or less, and most preferably 13.5 mass% or less.

[0102] When the content of isocyanate groups (isocyanate group content (NCO%)) in the first isocyanate component (solid content) is within the above range, excellent adhesive strength is achieved.

[0103] The content ratio of the first isocyanate component relative to the total amount of the polyisocyanate component is, for example, 50% by mass to 99% by mass, preferably 60% by mass to 97% by mass, more preferably 70% by mass to 95% by mass, even more preferably 75% by mass to 93% by mass, particularly preferably 80% by mass to 92% by mass, and most preferably 85% by mass to 91% by mass.

[0104] The content ratio of the first isocyanate component relative to the total amount of the polyisocyanate component is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, particularly preferably 80% by mass or more, and most preferably 85% by mass or more, and for example, 99% by mass or less, preferably 97% by mass or less, more preferably 95% by mass or less, even more preferably 93% by mass or less, particularly preferably 92% by mass or less, and most preferably 91% by mass or less.

[0105] In other words, the first isocyanate component is contained in an amount equal to or greater than the lower limit described above, and is therefore the main component of the polyisocyanate component.

[0106] When the content ratio of the first isocyanate component relative to the total amount of the polyisocyanate component is within the above range, the adhesive strength is excellent.

[0107] The first isocyanate component can contain known additives (such as stabilizers) (described below) as necessary.

[0108] [Second isocyanate component] The second isocyanate component comprises, and preferably consists of, a derivative of an aliphatic polyisocyanate.

[0109] Examples of the aliphatic polyisocyanate in the derivative of the aliphatic polyisocyanate (aliphatic polyisocyanate derivative) include linear aliphatic polyisocyanates and alicyclic polyisocyanates.

[0110] Examples of the chain aliphatic polyisocyanate include chain aliphatic polyisocyanate monomers. Examples of the chain aliphatic polyisocyanate monomers 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. The chain aliphatic polyisocyanates can be used alone or in combination of two or more kinds. Examples of the chain aliphatic polyisocyanate include chain aliphatic diisocyanates, and preferably pentamethylene diisocyanate and hexamethylene diisocyanate, and more preferably pentamethylene diisocyanate.

[0111] Examples of the alicyclic polyisocyanate include alicyclic polyisocyanate monomers. Examples of the alicyclic polyisocyanate monomers include alicyclic diisocyanates. Examples of the alicyclic diisocyanates include isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), methylene bis(cyclohexyl isocyanate) (H 12 Alicyclic polyisocyanates can be used alone or in combination of two or more.

[0112] 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) and hexamethylene diisocyanate (HDI), and most preferably pentamethylene diisocyanate (PDI).

[0113] In the derivative of aliphatic polyisocyanate (aliphatic polyisocyanate derivative), the derivative may be a modified product obtained by modifying the above-mentioned monomer by a known method. More specifically, the derivative may be, for example, a uretdione modified product, an isocyanurate modified product, an allophanate modified product, a polyol modified product, a biuret modified product, a urea modified product, an oxadiazinetrione modified product, an adduct modified product, or a carbodiimide modified product. The aliphatic polyisocyanate derivative may be used alone or in combination of two or more kinds.

[0114] In the aliphatic polyisocyanate derivative, the derivative is preferably an isocyanurate modified product and an adduct modified product from the viewpoint of adhesive properties. That is, the derivative of the aliphatic polyisocyanate is preferably an isocyanurate modified product of the aliphatic polyisocyanate and an adduct modified product of the aliphatic polyisocyanate. That is, the second isocyanate component includes a derivative of an aliphatic polyisocyanate, preferably an isocyanurate modified product of the aliphatic polyisocyanate and / or an adduct modified product of the aliphatic polyisocyanate, and more preferably an isocyanurate modified product of the aliphatic polyisocyanate and / or an adduct modified product of the aliphatic polyisocyanate.

[0115] From the viewpoint of adhesive properties, preferred examples of the derivatives of aliphatic polyisocyanates include an isocyanurate-modified product of hexamethylene diisocyanate (HDI), an adduct-modified product of hexamethylene diisocyanate (HDI), an isocyanurate-modified product of pentamethylene diisocyanate (PDI), and an adduct-modified product of pentamethylene diisocyanate (PDI), more preferred examples include an isocyanurate-modified product of hexamethylene diisocyanate (HDI) and an isocyanurate-modified product of pentamethylene diisocyanate (PDI), and even more preferred examples include an isocyanurate-modified product of pentamethylene diisocyanate (PDI). In other words, the derivative of the aliphatic polyisocyanate preferably includes at least one selected from the group consisting of an isocyanurate-modified product of hexamethylene diisocyanate (HDI), an adduct-modified product of hexamethylene diisocyanate (HDI), an isocyanurate-modified product of pentamethylene diisocyanate (PDI), and an adduct-modified product of pentamethylene diisocyanate (PDI).

[0116] The isocyanurate modified aliphatic polyisocyanate may include an allophanate modified aliphatic polyisocyanate.

[0117] When the isocyanurate-modified aliphatic polyisocyanate contains an allophanate-modified aliphatic polyisocyanate, the isocyanurate-modified aliphatic polyisocyanate is preferably in excess of the allophanate-modified aliphatic polyisocyanate. Specifically, the content of the allophanate-modified aliphatic polyisocyanate relative to the total amount of the isocyanurate-modified aliphatic polyisocyanate and the allophanate-modified aliphatic polyisocyanate is, for example, less than 50% by mass, preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less.

[0118] As the derivatives of aliphatic polyisocyanates, from the viewpoint of the increasing demand for reducing petroleum-derived carbon dioxide (CO2) emissions with the aim of achieving carbon neutrality, preferably, derivatives of aliphatic polyisocyanates containing plant-derived components are used, more preferably, isocyanurate-modified aliphatic polyisocyanates containing plant-derived components and adduct-modified aliphatic polyisocyanates derived from plants are used, still more preferably, isocyanurate-modified aliphatic polyisocyanates containing plant-derived components are used, and particularly preferably, isocyanurate-modified pentamethylene diisocyanate (PDI) containing a plant-derived component is used.

[0119] The content of the aliphatic polyisocyanate derivative relative to the total amount of the second isocyanate component is, for example, 90.0 mass% or more, preferably 95.0 mass% or more, more preferably 99.0 mass% or more, and even more preferably 100.0 mass%. In other words, the second isocyanate component preferably consists only of the aliphatic polyisocyanate derivative.

[0120] The second isocyanate component (solid content) has an average number of isocyanate groups in the range of, for example, 1.5 to 5.0, preferably 1.7 to 4.0, and more preferably 1.8 to 3.7.

[0121] The average number of isocyanate groups in the second isocyanate component (solid content) is, for example, 1.5 or more, preferably 1.7 or more, more preferably 1.8 or more, and for example, 5.0 or less, preferably 4.0 or less, more preferably 3.7 or less.

[0122] The second isocyanate component (solid content) has an isocyanate group equivalent of, for example, 140-500, preferably 150-400, and more preferably 160-300.

[0123] The second isocyanate component (solid content) has an isocyanate group equivalent of, for example, 140 or more, preferably 150 or more, more preferably 160 or more, and for example, 500 or less, preferably 400 or less, more preferably 300 or less.

[0124] The content of isocyanate groups in the second isocyanate component (solid content) (isocyanate group content (NCO%)) is, for example, 5.0 mass% to 30.0 mass%, preferably 10.0 mass% to 28.0 mass%, more preferably 15.0 mass% to 26.0 mass%, still more preferably 17.0 mass% to 24.0 mass%, and particularly preferably 20.0 mass% to 23.5 mass%.

[0125] The content of isocyanate groups in the second isocyanate component (solid content) (isocyanate group content (NCO%)) is, for example, 5.0 mass% or more, preferably 10.0 mass% or more, more preferably 15.0 mass% or more, even more preferably 17.0 mass% or more, particularly preferably 20.0 mass% or more, and for example, 30.0 mass% or less, preferably 28.0 mass% or less, more preferably 26.0 mass% or less, even more preferably 24.0 mass% or less, and particularly preferably 23.5 mass% or less.

[0126] The content ratio of the second isocyanate component relative to the total amount of the polyisocyanate component is, for example, 3 mass% to 30 mass%, preferably 5 mass% to 20 mass%, more preferably 7 mass% to 15 mass%, and still more preferably 9 mass% to 12 mass%.

[0127] The content ratio of the second isocyanate component relative to the total amount of the polyisocyanate component is, for example, 3 mass% or more, preferably 5 mass% or more, more preferably 7 mass% or more, even more preferably 9 mass% or more, and for example, 30 mass% or less, preferably 20 mass% or less, more preferably 15 mass% or less, even more preferably 12 mass% or less.

[0128] When the content ratio of the second isocyanate component relative to the total amount of the polyisocyanate component is within the above range, excellent adhesive strength can be obtained.

[0129] The polyisocyanate component is prepared by mixing the first isocyanate component and the second isocyanate component. The polyisocyanate component may further contain a third isocyanate component, if necessary.

[0130] The amount of the second isocyanate component mixed relative to 100 parts by mass of the first isocyanate component is, for example, 1 part by mass to 50 parts by mass, preferably 3 parts by mass to 40 parts by mass, more preferably 5 parts by mass to 30 parts by mass, even more preferably 8 parts by mass to 20 parts by mass, particularly preferably 10 parts by mass to 15 parts by mass, and most preferably 11 parts by mass to 13 parts by mass.

[0131] The amount of the second isocyanate component relative to 100 parts by mass of the first isocyanate component is, for example, 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, particularly preferably 10 parts by mass or more, and most preferably 11 parts by mass or more, and for example, 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, and most preferably 13 parts by mass or less.

[0132] [Tertiary isocyanate component] The third isocyanate component includes, for example, a carbodiimide-modified aromatic polyisocyanate, and is preferably a carbodiimide-modified aromatic polyisocyanate.

[0133] The carbodiimide-modified aromatic polyisocyanate is a reaction product of a carbodiimidization reaction of an aromatic polyisocyanate.

[0134] Examples of aromatic polyisocyanates include aromatic polyisocyanates similar to those described in the first raw material polyisocyanate, and more specifically, aromatic polyisocyanate monomers and their derivatives. From the viewpoint of adhesive properties, aromatic polyisocyanates are preferably aromatic polyisocyanate monomers, more preferably aromatic diisocyanates, and even more preferably diphenylmethane diisocyanate.

[0135] The carbodiimidization reaction may be a decarboxylation condensation reaction, for example, in which an aromatic polyisocyanate is heated in the presence of a carbodiimidization catalyst.

[0136] In addition, a commercially available product of a carbodiimide-modified aromatic polyisocyanate may be used as the third isocyanate component. Examples of commercially available products include Cosmonate LL (trade name, carbodiimide-modified diphenylmethane diisocyanate, isocyanate group (NCO group) content: 29.1%, manufactured by Mitsui Chemicals) and Coronate MX (trade name, carbodiimide-modified diphenylmethane diisocyanate, isocyanate group (NCO group) content: 29.0% by mass, manufactured by Tosoh).

[0137] In the third isocyanate component, the isocyanate group (NCO group) content of the carbodiimide-modified aromatic polyisocyanate is, for example, 10 to 50 mass%, preferably 20 to 40 mass%, and more preferably 25 to 30 mass%.

[0138] The isocyanate group (NCO group) content of the carbodiimide-modified aromatic polyisocyanate in the third isocyanate component is, for example, 10 mass% or more, preferably 20 mass% or more, more preferably 25 mass% or more, and for example, 50 mass% or less, preferably 40 mass% or less, more preferably 30 mass% or less.

[0139] In the third isocyanate component, the viscosity of the solid content of the carbodiimide-modified aromatic polyisocyanate at 25° C. is, for example, 10 mPa·s to 200 mPa·s, or preferably 20 mPa·s to 100 mPa·s.

[0140] 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.

[0141] When a third isocyanate component is contained, the content ratio of the third isocyanate component relative to the total amount of the polyisocyanate component is, for example, 5% by mass to 40% by mass, preferably 10% by mass to 35% by mass, more preferably 15% by mass to 30% by mass, and even more preferably 17% by mass to 20% by mass.

[0142] When a third isocyanate component is contained, the content ratio of the third isocyanate component to the total amount of the polyisocyanate component is, for example, 5 mass% or more, preferably 10 mass% or more, more preferably 15 mass% or more, even more preferably 17 mass% or more, and for example, 40 mass% or less, preferably 35 mass% or less, more preferably 30 mass% or less, even more preferably 20 mass% or less.

[0143] When a third isocyanate component is contained, the amount of the third isocyanate component per 100 parts by mass of the first isocyanate component is, for example, 1 part by mass to 70 parts by mass, preferably 10 parts by mass to 60 parts by mass, more preferably 15 parts by mass to 55 parts by mass, even more preferably 20 parts by mass to 50 parts by mass, and particularly preferably 23 parts by mass to 47 parts by mass.

[0144] When a third isocyanate component is contained, the amount of the third isocyanate component relative to 100 parts by mass of the first isocyanate component is, for example, 1 part by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, particularly preferably 23 parts by mass or more, and for example, 70 parts by mass or less, preferably 60 parts by mass or less, more preferably 55 parts by mass or less, even more preferably 50 parts by mass or less, and particularly preferably 47 parts by mass or less.

[0145] The polyisocyanate component includes a first isocyanate component and a second isocyanate component. The polyisocyanate component may further include a third isocyanate component. The polyisocyanate component preferably consists of the first isocyanate component and the second isocyanate component.

[0146] The isocyanate group content (isocyanate group content (NCO%)) of the isocyanate component (solid content) is, for example, 5.0 mass% to 30.0 mass%, preferably 8.0 mass% to 25.0 mass%, more preferably 10.0 mass% to 20.0 mass%, still more preferably 11.0 mass% to 18.0 mass%, and particularly preferably 13.0 mass% to 16.0 mass%.

[0147] The isocyanate group content (isocyanate group content (NCO%)) of the isocyanate component (solid content) is, for example, 5.0 mass% or more, preferably 8.0 mass% or more, more preferably 10.0 mass% or more, even more preferably 11.0 mass% or more, particularly preferably 13.0 mass% or more, and most preferably 14.0 mass% or more.

[0148] The isocyanate group content (isocyanate group content (NCO%)) of the isocyanate component (solid content) is, for example, 30.0 mass% or less, preferably 25.0 mass% or less, more preferably 20.0 mass% or less, even more preferably 18.0 mass% or less, particularly preferably 16.0 mass% or less, and most preferably 15.0 mass% or less.

[0149] When the content of isocyanate groups in the isocyanate component (solid content) (isocyanate group content (NCO%)) is within the above range, excellent adhesive strength is achieved.

[0150] <Polyol component> The polyol component contains a low molecular weight polyol and a high molecular weight polyol. The polyol component is preferably composed of a low molecular weight polyol and a high molecular weight polyol. The high molecular weight polyol is a relatively high molecular weight organic compound having two or more hydroxyl groups. The number average molecular weight (or molecular weight) of the high molecular weight polyol is, for example, 200 to 10,000, preferably 300 to 5,000, more preferably 350 to 3,000, and further preferably 400 to 1,000. The low molecular weight polyol is a relatively low molecular weight organic compound having two or more hydroxyl groups. The molecular weight of the low molecular weight polyol is, for example, less than 200, preferably 180 or less.

[0151] [High molecular weight polyol] High molecular weight polyols are polyols containing plant-derived components, in view of the increasing demand for reducing petroleum-derived carbon dioxide (CO2) emissions with the aim of achieving carbon neutrality. Note that a polyol containing plant-derived components is a polyol that uses plant-derived raw materials.

[0152] Specifically, the high molecular weight polyol is a vegetable oil polyol.As the vegetable oil polyol, for example, the vegetable oil polyol described in the first high molecular weight polyol can be mentioned.Specifically, as the high molecular weight polyol, preferably, the polyol includes vegetable oil and fatty acid derived from vegetable oil.

[0153] As the high molecular weight polyol, preferably, castor oil polyol is used, and more preferably, polyol containing fatty acid derived from castor oil is used.

[0154] Examples of polyols containing fatty acids derived from castor oil include ester-modified castor oil polyols obtained by reacting castor oil fatty acids with polyoxypropylene polyols, castor oil polyester polyols obtained by condensation reaction of hydroxycarboxylic acids such as castor oil fatty acids or hydrogenated castor oil fatty acids using a low molecular weight polyol (described later) as an initiator, and castor oil polyester polyols obtained by condensation reaction of hydroxycarboxylic acids such as castor oil fatty acids or hydrogenated castor oil fatty acids with castor oil.

[0155] The high molecular weight polyols can be used alone or in combination of two or more kinds.

[0156] The number average molecular weight (or molecular weight) of the high molecular weight polyol is, for example, 200 to 10,000, preferably 300 to 5,000, more preferably 350 to 3,000, and further preferably 400 to 1,000.

[0157] The number average molecular weight (or molecular weight) of the high molecular weight polyol is, for example, 200 or more, preferably 300 or more, more preferably 350 or more, even more preferably 400 or more, and for example, 10,000 or less, preferably 5,000 or less, more preferably 3,000 or less, even more preferably 1,000 or less.

[0158] The hydroxyl value (OH value) of the high molecular weight polyol is, for example, 200 mgKOH / g to 800 mgKOH / g, preferably 210 mgKOH / g to 500 mgKOH / g, more preferably 230 mgKOH / g to 400 mgKOH / g, still more preferably 250 mgKOH / g to 300 mgKOH / g, and particularly preferably 260 mgKOH / g to 280 mgKOH / g.

[0159] The hydroxyl value (OH value) of the high molecular weight polyol is 200 mgKOH / g or more, preferably 210 mgKOH / g or more, more preferably 230 mgKOH / g or more, even more preferably 250 mgKOH / g or more, and particularly preferably 260 mgKOH / g or more.

[0160] The hydroxyl value (OH value) of the high molecular weight polyol is, for example, 800 mgKOH / g or less, preferably 500 mgKOH / g or less, more preferably 400 mgKOH / g or less, even more preferably 300 mgKOH / g or less, and particularly preferably 280 mgKOH / g or less.

[0161] If the hydroxyl value of the high molecular weight polyol is equal to or greater than the lower limit, the polyol component after mixing the high molecular weight polyol and the low molecular weight polyol has excellent appearance and excellent adhesive properties. If the hydroxyl value of the high molecular weight polyol is within the above range, the polyol component after mixing the high molecular weight polyol and the low molecular weight polyol has even more excellent appearance and excellent adhesive properties.

[0162] The average number of hydroxyl groups in the high molecular weight polyol is, for example, 1.8 to 4.0, preferably 1.9 to 3.5, and more preferably 2.0 to 3.0, from the viewpoint of adhesive strength.

[0163] The average number of hydroxyl groups of the high molecular weight polyol is, from the viewpoint of adhesive strength, for example, 1.8 or more, preferably 1.9 or more, more preferably 2.0 or more, and for example, 4.0 or less, preferably 3.5 or less, more preferably 3.0 or less.

[0164] The content ratio of the high molecular weight polyol relative to the total amount of the polyol component is, from the viewpoint of adhesive strength, 89% by mass to 99% by mass, preferably 89% by mass to 98% by mass, more preferably 89% by mass to 96% by mass, even more preferably 90% by mass to 96% by mass, and particularly preferably 94% by mass to 96% by mass.

[0165] From the viewpoint of adhesive strength, the content ratio of the high molecular weight polyol relative to the total amount of the polyol component is 89 mass% or more, preferably 90 mass% or more, more preferably 91 mass% or more, even more preferably 92 mass% or more, particularly preferably 93 mass% or more, and most preferably 94 mass% or more.

[0166] The content ratio of the high molecular weight polyol relative to the total amount of the polyol component is 99 mass % or less, preferably 98 mass % or less, more preferably 97 mass % or less, and further preferably 96 mass % or less, from the viewpoint of adhesive strength.

[0167] When the content ratio of the high molecular weight polyol to the total amount of the polyol component is within the above range, the adhesive properties are excellent.

[0168] [Low molecular weight polyol] The low molecular weight polyol may be, for example, the same low molecular weight polyol as the first low molecular weight polyol described above.

[0169] The low molecular weight polyol contained in the polyol component preferably includes dihydric alcohols and trihydric alcohols. The dihydric alcohols include, for example, alkanediols 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), preferably 1,3-propanediol and 1,4-butanediol, more preferably 1,4-butanediol. The trihydric alcohols include, for example, glycerin and trimethylolpropane, preferably glycerin.

[0170] The low molecular weight polyols can be used alone or in combination of two or more kinds. For example, a dihydric alcohol can be used alone, and a dihydric alcohol and a trihydric alcohol can be used in combination. Preferred examples include 1,3-propanediol, 1,4-butanediol, and a combination of 1,4-butanediol and glycerin. More preferred examples include 1,4-butanediol.

[0171] As the low molecular weight polyol, from the viewpoint of increasing demand for reducing petroleum-derived carbon dioxide (CO2) emissions for the purpose of carbon neutrality, preferably, low molecular weight polyols containing plant-derived components are used, more preferably, 1,3-propanediol containing plant-derived components, 1,4-butanediol containing plant-derived components, and glycerin containing plant-derived components are used. The low molecular weight polyols containing plant-derived components are low molecular weight polyols using plant-derived raw materials.

[0172] The molecular weight of the low-molecular-weight polyol is, for example, 40 to 200, preferably 60 to 150, and more preferably 80 to 100, from the viewpoint of adhesive strength.

[0173] The hydroxyl value (OH value) of the low molecular weight polyol is, for example, 300 mgKOH / g to 5000 mgKOH / g, preferably 500 mgKOH / g to 3000 mgKOH / g, more preferably 700 mgKOH / g to 2500 mgKOH / g, still more preferably 900 mgKOH / g to 2000 mgKOH / g, and particularly preferably 1000 mgKOH / g to 2000 mgKOH / g.

[0174] The hydroxyl value (OH value) of the low molecular weight polyol is, for example, 300 mgKOH / g or more, preferably 500 mgKOH / g or more, more preferably 700 mgKOH / g or more, even more preferably 900 mgKOH / g or more, particularly preferably 1000 mgKOH / g or more, and for example, 5000 mgKOH / g or less, preferably 3000 mgKOH / g or less, more preferably 2500 mgKOH / g or less, even more preferably 2000 mgKOH / g or less.

[0175] The average number of hydroxyl groups of the low molecular weight polyol is, for example, 1.8 to 3.0, preferably 1.9 to 2.5, and more preferably 2.0 to 2.2, from the viewpoint of adhesive strength.

[0176] The average number of hydroxyl groups of the low molecular weight polyol is, from the viewpoint of adhesive strength, for example, 1.8 or more, preferably 1.9 or more, more preferably 2.0 or more, and for example, 3.0 or less, preferably 2.5 or less, more preferably 2.2 or less.

[0177] The content ratio of the low molecular weight polyol relative to the total amount of the polyol component is, from the viewpoint of adhesive strength, for example, 0 mass% to 11 mass%, preferably 1 mass% to 11 mass%, more preferably 2 mass% to 11 mass%, even more preferably 4 mass% to 10 mass%, and particularly preferably 4 mass% to 6 mass%.

[0178] The content ratio of the low molecular weight polyol relative to the total amount of the polyol component is, from the viewpoint of adhesive strength, for example, 0 mass% or more, preferably 1 mass% or more, more preferably 2 mass% or more, even more preferably 4 mass% or more, and for example, 11 mass% or less, preferably 10 mass% or less, more preferably 6 mass% or less.

[0179] The polyol component is prepared by mixing a low molecular weight polyol and a high molecular weight polyol.

[0180] The appearance of the polyol component after mixing the low molecular weight polyol and the high molecular weight polyol is preferably transparent.

[0181] The amount of low molecular weight polyol per 100 parts by mass of high molecular weight polyol is, for example, 1.0 parts by mass to 30.0 parts by mass, preferably 2.0 parts by mass to 20.0 parts by mass, more preferably 2.5 parts by mass to 15.0 parts by mass, even more preferably 3.0 parts by mass to 12.0 parts by mass, particularly preferably 4.0 parts by mass to 10.0 parts by mass, and most preferably 5.0 parts by mass to 8.0 parts by mass.

[0182] The amount of low molecular weight polyol per 100 parts by mass of high molecular weight polyol is, for example, 1.0 part by mass or more, preferably 2.0 parts by mass or more, more preferably 2.5 parts by mass or more, even more preferably 3.0 parts by mass or more, particularly preferably 4.0 parts by mass or more, and most preferably 5.0 parts by mass or more, and for example, 30.0 parts by mass or less, preferably 20.0 parts by mass or less, more preferably 15.0 parts by mass or less, even more preferably 12.0 parts by mass or less, particularly preferably 10.0 parts by mass or less, and most preferably 8.0 parts by mass or less.

[0183] The number average molecular weight of the polyol component is, for example, 200 to 4,000, or preferably 240 to 3,500, from the viewpoint of adhesive strength.

[0184] The average hydroxyl value (OH value) of the polyol component is, for example, 200 mgKOH / g to 1000 mgKOH / g, preferably 230 mgKOH / g to 700 mgKOH / g, more preferably 250 mgKOH / g to 500 mgKOH / g, still more preferably 270 mgKOH / g to 400 mgKOH / g, and particularly preferably 290 mgKOH / g to 350 mgKOH / g.

[0185] The average hydroxyl value (OH value) of the polyol component is, for example, 200 mgKOH / g or more, preferably 230 mgKOH / g or more, more preferably 250 mgKOH / g or more, even more preferably 270 mgKOH / g or more, particularly preferably 290 mgKOH / g or more, and for example, 1000 mgKOH / g or less, preferably 700 mgKOH / g or less, more preferably 500 mgKOH / g or less, even more preferably 400 mgKOH / g or less, particularly preferably 350 mgKOH / g or less.

[0186] The average number of hydroxyl groups in the polyol component is, for example, 2.0 to 3.0, preferably 2.0 to 2.9, and more preferably 2.0 to 2.8, from the viewpoint of adhesive strength.

[0187] The average number of hydroxyl groups in the polyol component is, from the viewpoint of adhesive strength, for example, 2.0 or more and, for example, 3.0 or less, preferably 2.9 or less, and more preferably 2.8 or less.

[0188] The amount of the polyol component per 100 parts by mass of the polyisocyanate component is, for example, 20 parts by mass to 150 parts by mass, preferably 30 parts by mass to 100 parts by mass, more preferably 35 parts by mass to 80 parts by mass, even more preferably 40 parts by mass to 70 parts by mass, particularly preferably 45 parts by mass to 65 parts by mass, and most preferably 50 parts by mass to 60 parts by mass.

[0189] The amount of the polyol component per 100 parts by mass of the polyisocyanate component is, for example, 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, particularly preferably 45 parts by mass or more, and most preferably 50 parts by mass or more, and for example, 150 parts by mass or less, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, particularly preferably 65 parts by mass or less, and most preferably 60 parts by mass or less.

[0190] The polyisocyanate component and the polyol component are mixed at a predetermined equivalent ratio. Specifically, the equivalent ratio (NCO / OH) of the isocyanate group in the polyisocyanate component to the hydroxyl group in the polyol component is, for example, 0.80 to 1.50, preferably 0.90 to 1.30, more preferably 1.00 to 1.20, and further preferably 1.05 to 1.15.

[0191] In addition, the equivalent ratio (NCO / OH) of the isocyanate groups in the polyisocyanate component to the hydroxyl groups of the polyol component is, for example, 0.80 or more, preferably 0.90 or more, more preferably 1.00 or more, even more preferably 1.05 or more, and for example, 1.50 or less, preferably 1.30 or less, more preferably 1.20 or less, even more preferably 1.15 or less.

[0192] In addition, the structural polyurethane adhesive may contain additives as necessary. Examples of additives include plasticizers, fillers, compatibilizers, urethane catalysts, antiaging agents, antioxidants, UV absorbers, heat stabilizers, polymeric light stabilizers, organic solvents, pigments, dyes, defoamers, dispersants, leveling agents, thixotropic agents, antiblocking agents, release agents, lubricants, interlayer adjusters, and viscosity adjusters. The content ratio of additives is not particularly limited and may be appropriately set according to the purpose and application.

[0193] The additive may be added to a mixture of the polyisocyanate component and the polyol component (such as a one-liquid curing adhesive). The additive may be contained in the base material described below, the curing agent described below, or both of them.

[0194] 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.

[0195] In the solventless 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.

[0196] 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.

[0197] Moreover, 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) for forming a cured product by blending (mixing) the base agent and curing agent, which are separately prepared, at the time of use. That is, a resin mixture (polyurethane mixture) is obtained by mixing the base agent and the curing agent, and a cured product (cured polyurethane product) is obtained by the curing reaction of the resin mixture. In the two-component curing adhesive, the base agent and the curing agent are mixed so that the equivalent ratio of the polyisocyanate component to the polyol component is the above-mentioned value.

[0198] 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 group-terminated prepolymer, and the second isocyanate component includes a derivative of an aliphatic polyisocyanate. The polyol component includes a low molecular weight polyol and a high molecular weight polyol. The high molecular weight polyol is a vegetable oil polyol, and has a hydroxyl value of 200 mgKOH / g or more, and the content ratio of the high molecular weight polyol to the total amount of the polyol component is within a predetermined range. Therefore, the structural polyurethane adhesive has excellent adhesive properties while using raw materials derived from plants.

[0199] Therefore, the structural polyurethane adhesive is suitable for use in structures made up of a plurality of members, for example, buildings, automobiles, transportation equipment, and ships.

[0200] 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.

[0201] From the viewpoint of workability, the viscosity at 25° C. of the mixture containing the polyisocyanate component and the polyol component is, for example, 100 mPa·s to 500,000 mPa·s, preferably 300 mPa·s to 100,000 mPa·s, and more preferably 300 mPa·s to 50,000 mPa·s.

[0202] The curing conditions and curing conditions are appropriately set. More specifically, the curing temperature is, for example, 10°C to 100°C, preferably 20°C to 80°C, and more preferably 20°C to 60°C. The curing time is, for example, 5 minutes to 5 hours, preferably 10 minutes to 2.5 hours, and more preferably 10 minutes to 1 hour. The curing temperature is, for example, 10°C to 80°C, preferably 15°C to 60°C, and more preferably 15°C to 40°C. The curing time is, for example, 1 hour to 2 weeks, and preferably 2 hours to 1 week.

[0203] This allows the structural polyurethane adhesive to harden and bond the various components well.

[0204] The structural polyurethane adhesive thus obtained contains the plant-derived raw material as described above. Specifically, the content of the plant-derived component in the structural polyurethane adhesive is, for example, 20% by mass to 80% by mass, preferably 30% by mass to 75% by mass, more preferably 40% by mass to 70% by mass, even more preferably 45% by mass to 66% by mass, particularly preferably 50% by mass to 62% by mass, and most preferably 55% by mass to 61% by mass.

[0205] In addition, the content of plant-derived components in the structural polyurethane adhesive is, for example, 20% by mass or more, preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, particularly preferably 50% by mass or more, and most preferably 55% by mass or more, and for example, 80% by mass or less, preferably 75% by mass or less, more preferably 70% by mass or less, even more preferably 66% by mass or less, particularly preferably 62% by mass or less, and most preferably 61% by mass or less.

[0206] The content of plant-derived components in the structural polyurethane adhesive can be determined by the biomass ratio measurement described in the Examples below. EXAMPLES

[0207] 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 based on mass unless otherwise specified. In addition, the specific numerical values ​​of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit value (numerical value defined as "less than or equal to" or "less than") or lower limit value (numerical value defined as "more than or equal to" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention".

[0208] <Preparation of isocyanate component (NCO component)> (Preparation Example 1) First Isocyanate Component (1-A) As the first raw material polyol, 137.7 parts by mass of Actocol D-1000 (trade name, polyoxypropylene glycol, number average molecular weight: 1000, average hydroxyl value: 112 mgKOH / g, manufactured by Mitsui Chemicals), 149.9 parts by mass of Takelac P-24 (trade name, EO-capped polyoxypropylene glycol, number average molecular weight: about 2000, average hydroxyl value: 56 mgKOH / g, manufactured by Mitsui Chemicals), and 149.9 parts by mass of Actocol T-1000 (trade name, polyoxypropylene triol, number average molecular weight: 1 107.5 parts by mass of BioPTMG1000 (trade name, polytetramethylene ether glycol containing plant-derived components, number average molecular weight: 1000, average hydroxyl value: 168 mg KOH / g, manufactured by Mitsui Chemicals Co., Ltd.), and 207.0 parts by mass of BioPTMG1000 (trade name, polytetramethylene ether glycol containing plant-derived components, number average molecular weight: 1000, hydroxyl value: 114 mg KOH / g, manufactured by Mitsubishi Chemical Co., Ltd.), 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 (stabilizer) were mixed. The equivalent ratio (NCO / OH) at this time was 2.8. Next, the obtained mixture was stirred in a nitrogen gas flow at 60°C for 1 hour, and further stirred at 80°C for 8 hours to cause a urethane reaction. As a result, a first isocyanate component (1-A) containing a first isocyanate group-terminated urethane prepolymer (MDI prepolymer) was obtained. The solids concentration of the MDI prepolymer was 100%, the amine equivalent was 489, and the isocyanate group (NCO group) content was 8.6 mass%.

[0209] (Preparation Example 2) First Isocyanate Component (1-B) As the first raw material polyol, 571.1 parts by mass of BioPTMG1000 (trade name, polytetramethylene ether glycol containing plant-derived components, number average molecular weight: 1000, hydroxyl value: 114 mgKOH / g, manufactured by Mitsubishi Chemical Corporation), 428.7 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI) as the first raw material polyisocyanate, and 0.1 parts by mass of o-toluenesulfonamide (stabilizer) were mixed. The equivalent ratio (NCO / OH) at this time was 3.0. Next, the obtained mixture was stirred in a nitrogen gas flow at 60°C for 1 hour, and further stirred at 80°C for 8 hours to cause a urethane reaction. As a result, a first isocyanate component (1-B) containing a first isocyanate group-terminated urethane prepolymer (MDI prepolymer) was obtained. The solid concentration of the MDI prepolymer was 100%, the amine equivalent was 433, and the isocyanate group (NCO group) content was 9.7%.

[0210] (Preparation Example 3) First Isocyanate Component (1-C) As the first raw material polyol, BioPTMG650 (trade name, polytetramethylene ether glycol containing plant-derived components, number average molecular weight: 650, hydroxyl value: 174 mg KOH / g, manufactured by Mitsubishi Chemical Corporation) 415.7 parts by mass, Actocol T-1000 (trade name, polyoxypropylene triol, number average molecular weight: 1000, average hydroxyl value: 168 mg KOH / g, manufactured by Mitsui Chemicals, Inc.) 23.8 parts by mass, 4,4'-diphenylmethane diisocyanate (MDI) 560.3 parts by mass as the first raw material polyisocyanate, and o-toluenesulfonamide (stabilizer) 0.1 parts by mass were mixed. The equivalent ratio (NCO / OH) at this time was 3.3. Next, the obtained mixture was stirred at 60 ° C. for 1 hour in a nitrogen stream, and further stirred at 80 ° C. for 8 hours to cause a urethane reaction. This resulted in the production of a first isocyanate component (1-C) containing a first isocyanate group-terminated urethane prepolymer (MDI prepolymer). The solids concentration of the MDI prepolymer was 100%, the amine equivalent was 318, and the isocyanate group (NCO group) content was 13.2% by mass.

[0211] (Preparation Example 4) First Isocyanate Component (1-D) As the first raw material polyol, 451.5 parts by mass of deodorized refined castor oil (DR) (trade name, castor oil polyol, average hydroxyl value: 165 mgKOH / g, manufactured by Toyokuni Oil Co., Ltd.), 548.3 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI) as the first raw material polyisocyanate, and 0.1 parts by mass of o-toluenesulfonamide (stabilizer) were mixed. The equivalent ratio (NCO / OH) at this time was 3.3. Next, the obtained mixture was stirred in a nitrogen gas flow at 60°C for 1 hour, and further stirred at 80°C for 8 hours to cause a urethane reaction. As a result, a first isocyanate component (1-D) containing a first isocyanate group-terminated urethane prepolymer (MDI prepolymer) was obtained. The solid content concentration of the MDI prepolymer was 100%, the amine equivalent was 328, and the isocyanate group (NCO group) content was 12.8% by mass.

[0212] (Preparation Example 5) Second Isocyanate Component (Takenate D-170N) As the second isocyanate component, Takenate D-170N (product name, aliphatic polyisocyanate derivative (isocyanurate modified product of hexamethylene diisocyanate), solid content: 100 mass %, isocyanate group content: 20.7 mass %, manufactured by Mitsui Chemicals, Inc.) was prepared.

[0213] (Preparation Example 6) Second isocyanate component (STABIO D-376N) As the second isocyanate component, STABIO D-376N (product name, aliphatic polyisocyanate derivative containing plant-derived components (isocyanurate modified pentamethylene diisocyanate), solid content: 100 mass%, isocyanate group content: 22.0 mass%, manufactured by Mitsui Chemicals) was prepared.

[0214] (Preparation Example 7) Second Isocyanate Component (PDI / TMP) Into a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of STABIOPDI (trade name, pentamethylene diisocyanate, manufactured by Mitsui Chemicals, Inc.) and 50.0 parts by mass of trimethylolpropane (TMP) as a low molecular weight polyol were charged. At this time, the equivalent ratio (NCO / OH) was 5.8. After heating up to 75°C under a nitrogen atmosphere and confirming that the trimethylolpropane had dissolved, the reaction was carried out at 83°C until the isocyanate group concentration reached the calculated value (theoretical amount of unreacted isocyanate groups: 41.0% by mass).

[0215] Next, this reaction solution was passed through a thin film distillation apparatus (temperature 130°C, vacuum degree 93.3 Pa) and distilled until the amount of residual PDI monomer was 1.0 mass% or less, thereby obtaining a second isocyanate component (PDI / TMP) containing an aliphatic polyisocyanate derivative (TMP adduct modified product of pentamethylene diisocyanate). The isocyanate group (NCO group) content of the obtained aliphatic polyisocyanate derivative was 18.7 mass%.

[0216] (Preparation Example 8) Second Isocyanate Component (HDI / TMP) Into a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of hexamethylene diisocyanate (HDI) (manufactured by Tosoh Corporation) and 45.8 parts by mass of trimethylolpropane as a low molecular weight polyol were charged. At this time, the equivalent ratio (NCO / OH) was 5.8. The temperature was raised to 75°C under a nitrogen atmosphere, and after confirming that the trimethylolpropane had dissolved, the reaction was carried out at 83°C until the isocyanate group concentration reached the calculated value (theoretical amount of unreacted isocyanate groups: 37.9% by mass).

[0217] Next, this reaction solution was passed through a thin film distillation apparatus (temperature 130°C, vacuum degree 93.3 Pa) and distilled until the amount of remaining HDI monomer was 1.0 mass% or less, thereby obtaining a second isocyanate component (HDI / TMP) containing an aliphatic polyisocyanate derivative (TMP adduct modified product of hexamethylene diisocyanate). The isocyanate group content of the obtained polyisocyanate modified product was 17.3 mass%.

[0218] (Preparation Example 9) Third Isocyanate Component (Cosmonate LL) As the third isocyanate component, Cosmonate LL (product name, carbodiimide modified diphenylmethane diisocyanate, isocyanate group (NCO group) content: 29.1 mass %, manufactured by Mitsui Chemicals, Inc.) was prepared.

[0219] <Preparation of polyol component> (Preparation Example 10) High molecular weight polyol (Actocol EP-330N) As a high molecular weight polyol, Actocol EP-330N (product name, polyoxyalkylene triol (propylene oxide-ethylene oxide block copolymer), terminal oxyethylene group content: 15 mass%, number average molecular weight: 5000, hydroxyl value: 33.0 mgKOH / g, manufactured by Mitsui Chemicals) was prepared.

[0220] (Preparation Example 11) High molecular weight polyol (URIC H30) As the high molecular weight polyol, URIC H30 (trade name, castor oil polyol, average functionality: 2.7, hydroxyl value: 160.0 mgKOH / g, manufactured by Ito Oil Mills) was prepared.

[0221] (Preparation Example 12) High molecular weight polyol (URIC F85) As the high molecular weight polyol, URIC F85 (trade name, castor oil polyol, average functionality: 3.0, hydroxyl value 174.0 mgKOH / g, manufactured by Ito Oil Mills) was prepared.

[0222] (Preparation Example 13) High molecular weight polyol (URIC H854) As the high molecular weight polyol, URIC H854 (trade name, castor oil polyol, average functionality: 3.0, hydroxyl value 210.0 mgKOH / g, manufactured by Ito Oil Mills) was prepared.

[0223] (Preparation Example 14) High molecular weight polyol (HS 2G-270B) As the high molecular weight polyol, HS 2G-270B (product name, castor oil polyol, average functionality: 2.0, hydroxyl value 270.0 mgKOH / g, manufactured by Toyokuni Oil Mills) was prepared.

[0224] (Preparation Example 15) Low molecular weight polyol (biomass BDO) As a low molecular weight polyol, biomass BDO (product name, 1,4-butanediol containing plant-derived components, hydroxyl value 1244.0 mgKOH / g, MP manufactured by Gokyo Food & Chemical Co., Ltd.) was prepared.

[0225] (Preparation Example 16) Low molecular weight polyol (biomass PDO) As a low molecular weight polyol, biomass PDO (product name, 1,3-propanediol containing plant-derived components, hydroxyl value 1472.6 mg KOH / g, MP manufactured by Gokyo Food & Chemical Co., Ltd.) was prepared.

[0226] (Preparation Example 17) Low molecular weight polyol (glycerin) As a low molecular weight polyol, glycerin (containing plant-derived components, hydroxyl value 1829.4 mg KOH / g) was prepared.

[0227] <Preparation of structural polyurethane adhesive> Example 1 The first isocyanate component and the second isocyanate component were mixed according to the recipe shown in Table 1. In this way, a polyisocyanate component (main component) was obtained.

[0228] In addition, a high molecular weight polyol and a low molecular weight polyol were mixed according to the formula shown in Table 1, and an amine catalyst (DABCO 33LV) was added to the mixture so that the amount of the resulting mixture in the cured structural polyurethane adhesive was about 600 ppm, and a tin catalyst (DBTDL) was added to the mixture so that the amount of the resulting mixture in the cured structural polyurethane adhesive was about 100 ppm. This resulted in the production of a polyol component (curing agent).

[0229] This resulted in the structural polyurethane adhesive of Example 1 comprising the polyisocyanate component (base agent) and the polyol component (curing agent).

[0230] Examples 2 to 21 A structural polyurethane adhesive was obtained in the same manner as in Example 1, except that the polyisocyanate component (base agent) and the polyol component (curing agent) were obtained according to the formulations shown in Tables 1 to 4.

[0231] In Examples 2 and 3, the second isocyanate component (PDI / TMP) obtained in Preparatory Example 7 or the second isocyanate component (HDI / TMP) obtained in Preparatory Example 8 was mixed with the first isocyanate component (1-A) obtained in Preparatory Example 1 while still in a heated state after thin-film distillation. In Examples 17 to 21, the first isocyanate component, the second isocyanate component, and the third isocyanate component were mixed to obtain a polyisocyanate component (main component).

[0232] In addition, in Examples 6 to 15, a high molecular weight polyol and a low molecular weight polyol were mixed, and an amine catalyst (DABCO 33LV) was added to the mixture so that the amount in the cured structural polyurethane adhesive was approximately 1000 ppm, and a tin catalyst (DBTDL) was added to the mixture so that the amount in the cured structural polyurethane adhesive was approximately 200 ppm.

[0233] Comparative Examples 1 to 6 A structural polyurethane adhesive was obtained in the same manner as in Example 1, except that the polyisocyanate component (base agent) and the polyol component (curing agent) were obtained according to the formulations shown in Tables 1 and 2.

[0234] In Comparative Example 1, high molecular weight polyol and low molecular weight polyol were mixed, and only amine catalyst (DABCO 33LV) was added to the mixture so that the amount of the catalyst in the cured structural polyurethane adhesive was about 700 ppm. In Comparative Examples 2 to 4 and 6, high molecular weight polyol and low molecular weight polyol were mixed, and amine catalyst (DABCO 33LV) was added to the mixture so that the amount of the catalyst in the cured structural polyurethane adhesive was about 1000 ppm, and tin catalyst (DBTDL) was added to the mixture so that the amount of the catalyst in the cured structural polyurethane adhesive was about 200 ppm. In addition, in Comparative Examples 2 and 6, low molecular weight polyol was not used.

[0235] <Evaluation> [Appearance after mixing polyol components] In each of the Examples and Comparative Examples, the appearance of the polyol component (curing agent) obtained according to the formulation shown in Tables 1 to 4 was visually observed. The results are shown in Tables 1 to 4.

[0236] [Biomass measurement] In each Example and Comparative Example, the polyisocyanate component and the polyol component were mixed in the equivalent ratio (NCO / OH) shown in Tables 1 to 4, and then cured for one week to obtain a cured product. As described in ASTM (American Standard Test Method) D6866 (Standard Test Method for Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis), each of the obtained cured products was burned to produce CO2, and the accurately quantified CO2 gas was put into an AMS (Accelerated Mass Spectrometry) device to measure the content of carbon with mass number 14, the content of carbon with mass number 12 and the content of carbon with mass number 13, and the biomass degree was calculated by comparing with the abundance rate of carbon with mass number 14 present in the atmosphere or petrochemical products. The biomass degree indicates the content rate of plant-derived components in the structural polyurethane adhesive of each Example and Comparative Example, and is expressed as mass%.

[0237] [Gelation time] In each of the Examples and Comparative Examples 1, 2, and 6, the polyisocyanate component and the polyol component were mixed in the equivalent ratio (NCO / OH) shown in Tables 1 to 4, and then left to stand under conditions of 23°C and 50% RH. Each mixed liquid was lifted with a spatula at any given time, and the time when the mixed liquid stopped flowing was defined as the gelation time. From the viewpoint of production efficiency, the shorter the gelation time, the better, so it was evaluated according to the following criteria. The results are shown in Tables 1 to 4. {standard} ○: Less than 30 minutes △: 30 minutes or more, 60 minutes or less ×: Over 60 minutes

[0238] [Adhesion test (initial)] A polypropylene plate (J707G, Prime Polymer (PP)) was cut to a width of 25 mm to prepare a test piece. Next, the surface of the PP was degreased and cleaned with isopropyl alcohol, and then dried. This was corona-treated just before preparing the adhesion test specimen, and the wettability (JIS K 6768 (1999)) was adjusted to 40 dyn / cm or more, and this was used as the adherend 1.

[0239] On the other hand, a cold-rolled steel plate (SPCC) was cut to a width of 25 mm and cathodic electrocoating (ED) was performed to prepare an ED-SPCC plate (JIS G 3141 (SPCC, SD), test piece manufactured). Next, the surface of the ED-SPCC was degreased and washed with isopropyl alcohol, and then dried. This was used as the adherend 2.

[0240] In each of the Examples and Comparative Examples 1, 2, and 6, the polyisocyanate component and the polyol component were mixed in an equivalent ratio (NCO / OH) shown in Tables 1 to 4.

[0241] Thereafter, the above mixture was applied to the adherend 1, and the adherend 1 and the adherend 2 were brought into close contact with each other so that the adhesion area was 25 mm × 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. In addition, glass beads (ASGB-60, AS ONE, 0.250-0.355 mm) were placed in an appropriate amount (about several dozen beads) for layer thickness adjustment on the adhesive surface (surface after the above mixture was applied to the adherend 1). In this way, an adhesion test specimen was obtained.

[0242] Then, the shear adhesive strength (hereinafter, adhesive strength) [MPa] between adherend 1 and adherend 2 was measured at a tensile speed of 50 mm / min using a tensile tester (U-4410, manufactured by Orientec Co., Ltd.). The results are shown in Tables 1 to 4.

[0243] The peeling mode (peeling state) when the above-mentioned shear adhesive strength was measured was evaluated according to the following criteria. The results are shown in Tables 1 to 4. {standard} ○: Material or cohesive failure △: Thin layer material failure ×: Interfacial peeling

[0244] Material failure: Failure occurring within adherend 1 or adherend 2 Cohesive failure: Failure occurring within the adhesive Thin film material failure: Failure at the surface of adherend 1 or adherend 2 Interfacial peeling: Failure in which the adhesive peels off at the interface between the adhesive and either the adherend 1 or the adherend 2.

[0245] [Adhesion test (humid heat resistance)] The adhesion test specimen obtained in the above adhesion test (initial stage) was left in a thermo-hygrostat adjusted to 85°C and 85% RH for one week, and then the shear bond strength was measured in the same manner as above. In addition, the peel mode (peeling state) when the shear bond strength was measured was also evaluated according to the same criteria as above. The results are shown in Tables 1 to 4.

[0246] [Table 1]

[0247] [Table 2]

[0248] [Table 3]

[0249] [Table 4]

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 second isocyanate component comprises a derivative of an aliphatic polyisocyanate; The polyol component includes a high molecular weight polyol and a low molecular weight polyol, the high molecular weight polyol is a vegetable oil polyol; The hydroxyl value of the high molecular weight polyol is 200 mgKOH / g or more, A structural polyurethane adhesive, wherein the content of the high molecular weight polyol relative to the total amount of the polyol component is 89 mass % or more and 99 mass % or less.

2. 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 is an aromatic polyisocyanate, 2. The structural polyurethane adhesive of claim 1, wherein the first raw material polyol comprises polytetramethylene ether glycol and / or vegetable oil polyol that includes plant-derived components.

3. The structural polyurethane adhesive according to claim 1 , wherein the first isocyanate component has an isocyanate group content of 9.0 mass % or more.

4. The structural polyurethane adhesive of claim 1 , wherein the derivative of the aliphatic polyisocyanate comprises an isocyanurate modified product of an aliphatic polyisocyanate and / or an adduct modified product of an aliphatic polyisocyanate.

5. the polyisocyanate component further comprises a third isocyanate component; The structural polyurethane adhesive of claim 1 , wherein the third isocyanate component is a carbodiimide modified aromatic polyisocyanate.

6. The structural polyurethane adhesive according to claim 1 , wherein a content ratio of the high molecular weight polyol relative to a total amount of the polyol component is 96 mass % or less.

7. The structural polyurethane adhesive according to claim 1 , wherein the polyisocyanate component has an isocyanate group content of 10.0 mass % or more.

8. 10. The structural polyurethane adhesive of claim 1, wherein said high molecular weight polyol is a castor oil polyol.

9. The structural polyurethane adhesive according to claim 1 , wherein the high molecular weight polyol has a hydroxyl value of 250 mg KOH / g or greater.

10. 2. The structural polyurethane adhesive according to claim 1, wherein the structural polyurethane adhesive has a plant-derived component content of 20% by mass or more and 80% by mass or less.

11. The structural polyurethane adhesive according to any one of claims 1 to 10, which is a two-component curing adhesive comprising a base agent containing the polyisocyanate component and a curing agent containing the polyol component.

12. The structural polyurethane adhesive according to any one of claims 1 to 10, which is a solvent-free adhesive.

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