Structural polyurethane adhesive

Abstract

This structural polyurethane adhesive comprises a polyisocyanate component and a polyol component. The polyisocyanate component comprises an isocyanate-terminated urethane prepolymer that is a reaction product of a first starting-material polyisocyanate containing an aromatic polyisocyanate and a first starting-material polyol containing a macro polyol. The polyol component comprises a hydroxyl-terminated urethane prepolymer that is a reaction product of a second starting-material polyisocyanate containing an aromatic / aliphatic polyisocyanate and / or an alicyclic polyisocyanate and a second starting-material polyol containing a macro polyol, and a low molecular weight polyol.

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, polyurethane adhesives have been widely used in various industrial fields. Known examples of polyurethane adhesives include two-component curing polyurethane adhesives that contain a polyisocyanate component and a polyol component.

[0003] For example, the following formulation has been proposed as a two-component curing polyurethane adhesive. That is, the two-component coating agent comprises a urethane prepolymer composition and a polyisocyanate crosslinking agent, and the urethane prepolymer composition contains a reaction product of hexamethylene diisocyanate, copolycarbonate diol, and ethylene glycol. In addition, such a two-component coating agent is used in the manufacture of synthetic imitation leather (see, for example, Patent Document 1 (Example 1 and Application Example 1)). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-105250 A Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, the physical properties required for a polyurethane adhesive vary depending on the field of use. For example, when a polyurethane adhesive is used to bond each component of a structure composed of multiple components, the polyurethane adhesive is required to have particularly excellent adhesive strength. In this regard, the above-mentioned polyurethane adhesive has a problem in that its adhesive properties are insufficient.

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

[0007] The present invention [1] contains a polyisocyanate component and a polyol component, the polyisocyanate component contains a first raw material polyisocyanate containing an aromatic polyisocyanate, and an isocyanate group-terminated urethane prepolymer which is a reaction product of a first raw material polyol containing a macropolyol, and the polyol component contains an aromatic aliphatic polyisocyanate. and / or alicyclic polyisocyanates and a structural polyurethane adhesive comprising a hydroxyl-terminated urethane prepolymer which is a reaction product of a second raw material polyisocyanate comprising a macropolyol and a second raw material polyol comprising a macropolyol, and a low molecular weight polyol.

[0008] The present invention [2] comprises the structural polyurethane adhesive described in [1] above, in which the proportion of the hydroxyl group-terminated urethane prepolymer is 2 mass% or more and 30 mass% or less relative to the total amount of the polyol component.

[0009] The present invention [3] includes the structural polyurethane adhesive described in [1] or [2] above, in which the polyisocyanate component further contains a carbodiimide-modified aromatic polyisocyanate monomer.

[0010] The present invention [4] comprises the structural polyurethane adhesive according to any one of the above [1] to [3], wherein the polyol component further contains a polyether polyol having an average number of 3 or more hydroxyl groups.

[0011] The present invention [5] comprises the structural polyurethane adhesive according to any one of the above [1] to [4], in which the aromatic polyisocyanate comprises diphenylmethane diisocyanate.

[0012] The present invention [6] comprises the structural polyurethane adhesive according to any one of the above [1] to [5], in which the araliphatic polyisocyanate comprises xylylene diisocyanate.

[0013] The present invention [7] comprises the structural polyurethane adhesive according to any one of the above [1] to [6], wherein the hydroxyl equivalent of the hydroxyl-terminated urethane prepolymer is 550 or less.

[0014] The present invention [8] comprises the structural polyurethane adhesive according to any one of the above [1] to [7], which is a two-component curing adhesive comprising a base agent containing the polyisocyanate component and a curing agent containing the polyol component.

[0015] The present invention [9] comprises the structural polyurethane adhesive according to any one of the above [1] to [8], which is a solvent-free adhesive. Effect of the Invention

[0016] In the structural polyurethane adhesive of the present invention, the polyisocyanate component includes an isocyanate-terminated urethane prepolymer which is a reaction product of a first raw material polyisocyanate including an aromatic polyisocyanate and a first raw material polyol including a macropolyol, and the polyol component includes an aromatic aliphatic polyisocyanate. and / or alicyclic polyisocyanates The structural polyurethane of the present invention contains a hydroxyl-terminated urethane prepolymer, which is a reaction product of a second raw material polyisocyanate containing the above-mentioned compound and a second raw material polyol containing a macropolyol, and a low molecular weight polyol. Therefore, the structural polyurethane of the present invention has excellent adhesive properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 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."

[0018] More specifically, the structural polyurethane adhesive contains a polyisocyanate component and a polyol component as essential components. The polyisocyanate component is a component that contains a free isocyanate group. The polyol component is a component that contains a free hydroxyl group.

[0019] 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.

[0020] The polyisocyanate component contains a urethane prepolymer having two or more isocyanate groups at the molecular terminals (hereinafter referred to as an isocyanate group-terminated urethane prepolymer).

[0021] The isocyanate-terminated urethane prepolymer is a reaction product of a first raw material polyisocyanate and a first raw material polyol. The first raw material polyisocyanate and the first raw material polyol react with each other so that the isocyanate groups are in excess relative to the hydroxyl groups.

[0022] The first raw material polyisocyanate contains an aromatic polyisocyanate, and preferably consists of an aromatic polyisocyanate. Examples of the aromatic polyisocyanate include an aromatic polyisocyanate monomer and an aromatic polyisocyanate derivative.

[0023] 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. These can be used alone or in combination of two or more.

[0024] The aromatic polyisocyanate derivative may be a modified product obtained by modifying the aromatic polyisocyanate monomer by a known method. More specifically, the aromatic polyisocyanate derivative may be, for example, a multimer, 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 polymethylene polyphenylene polyisocyanate. These may be used alone or in combination of two or more kinds.

[0025] These aromatic polyisocyanates can be used alone or in combination of two or more kinds. As the aromatic polyisocyanate, from the viewpoint of adhesive properties, preferably, an aromatic polyisocyanate monomer is used, more preferably, an aromatic diisocyanate is used, and further preferably, diphenylmethane diisocyanate is used.

[0026] In other words, the first raw material polyisocyanate preferably contains diphenylmethane diisocyanate, and more preferably consists of diphenylmethane diisocyanate.

[0027] The first raw material polyol contains a macropolyol as an essential component. The macropolyol is a relatively high molecular weight organic compound having two or more hydroxyl groups.

[0028] The number average molecular weight of the macropolyol (hereinafter, the first macropolyol) in the first raw material polyol is 200 or more. The number average molecular weight of the first macropolyol is usually 15000 or less. The number average molecular weight is a polystyrene-equivalent molecular weight measured by gel permeation chromatography (hereinafter the same).

[0029] As the first macropolyol, among the second macropolyols described later, one having a molecular weight of 200 to 15000 is used. As the first macropolyol, preferably, polyether polyol (described later), polyester polyol (described later), and polycarbonate polyol (described later) are used, and more preferably, polyether polyol (described later) is used.

[0030] The number average molecular weight of the first macropolyol is, for example, 200 or more, preferably 300 or more, more preferably 400 or more. The number average molecular weight of the first macropolyol is, for example, 15,000 or less, preferably 13,000 or less, more preferably 12,000 or less, further preferably 10,000 or less, further preferably 8,000 or less, particularly preferably 5,000 or less.

[0031] The hydroxyl equivalent of the first macropolyol is, for example, 150 or more, preferably 200 or more. The hydroxyl equivalent of the first macropolyol is, for example, 10000 or less, preferably 8000 or less. The hydroxyl equivalent can be calculated from the hydroxyl value.

[0032] The average number of hydroxyl groups of the first macropolyol is, for example, 1.8 or more, preferably 2 or more. The average number of hydroxyl groups of the first macropolyol is, for example, 6 or less, preferably 4 or less, more preferably 3 or less.

[0033] The hydroxyl value and hydroxyl equivalent can be measured, for example, in accordance with Method A or Method B of JIS K 1557-1 (2007). The average number of hydroxyl groups can be calculated from the hydroxyl value, hydroxyl equivalent, and molecular weight. The hydroxyl value, hydroxyl equivalent, and average number of hydroxyl groups can also be calculated from the charge ratio of the raw material components (same below).

[0034] As the first raw material polyol, it is particularly preferable to use a first macropolyol having an average number of 2 hydroxyl groups and a first macropolyol having an average number of 3 hydroxyl groups in combination.

[0035] When a first macropolyol having an average number of hydroxyl groups of 2 and a first macropolyol having an average number of hydroxyl groups of 3 are used in combination, the first macropolyol having an average number of hydroxyl groups of 3 is, for example, more than 50 parts by mass, preferably 60 parts by mass or more, relative to the total amount of 100 parts by mass. The first macropolyol having an average number of hydroxyl groups of 3 is, for example, 90 parts by mass or less, preferably 80 parts by mass or less. The first macropolyol having an average number of hydroxyl groups of 2 is, for example, 10 parts by mass or more, preferably 20 parts by mass or more. The first macropolyol having an average number of hydroxyl groups of 2 is, for example, less than 50 parts by mass, preferably 40 parts by mass or less.

[0036] The first raw material polyol may contain a low molecular weight polyol as an optional component. The low molecular weight polyol is a relatively low molecular weight organic compound having two or more hydroxyl groups.

[0037] The molecular weight of the low-molecular-weight polyol in the first raw material polyol (hereinafter, referred to as the first low-molecular-weight polyol) is less than 200, and preferably 180 or less.

[0038] 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. These can be used alone or in combination of two or more types.

[0039] 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 is, for example, 30 parts by mass or less, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and particularly preferably 0 parts by mass, relative to 100 parts by mass of the total amount of the first raw material polyol. That is, from the viewpoint of adhesive properties, the first raw material polyol preferably does not contain the first low molecular weight polyol and is composed of the first macro polyol.

[0040] The isocyanate-terminated urethane 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.

[0041] In the urethane reaction, the equivalent ratio (NCO / OH) of the isocyanate group in the first raw material polyisocyanate to the hydroxyl group in the first raw material polyol is, for example, more than 1, preferably 1.1 or more, more preferably 1.3 or more, even more preferably 1.5 or more, and particularly preferably 1.9 or more. In addition, the equivalent ratio (NCO / OH) is, for example, 50 below, preferably 15 or less, more preferably 10 or less, even more preferably 3 or less, and particularly preferably 2.5 or less.

[0042] 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 or higher, for example, 120°C or lower, preferably 100°C or lower. The reaction time is, for example, 0.5 hours or higher, preferably 1 hour or higher, for example, 24 hours or lower, preferably 15 hours or lower. 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 (reaction without solvent) is adopted.

[0043] In the urethane reaction, a known urethane catalyst is added as necessary. If necessary, unreacted polyisocyanate is removed by a known method. This produces a first isocyanate component containing an isocyanate group-terminated urethane prepolymer.

[0044] As the isocyanate group-terminated urethane prepolymer, preferably, an isocyanate group-terminated urethane prepolymer which is a reaction product of an aromatic polyisocyanate and a polyether polyol is used, and more preferably, an isocyanate group-terminated urethane prepolymer which is a reaction product of diphenylmethane diisocyanate and a polyether polyol is used.

[0045] In addition, the polyisocyanate component may contain free (unreacted) first raw material polyisocyanate, organic solvent, and urethane catalyst, if 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.

[0046] The content of free (unreacted) first raw material polyisocyanate is, for example, 8.0 mass % or less, or preferably 5.0 mass % or less, relative to the total amount of the polyisocyanate component, from the viewpoint of adhesive properties.

[0047] The average number of isocyanate groups in the isocyanate group-terminated urethane prepolymer is, for example, 1.2 or more, preferably 1.5 or more, and more preferably 2 or more. The average number of isocyanate groups in the first isocyanate component (solid content) is, for example, 4 or less, preferably 3 or less.

[0048] The isocyanate group equivalent of the isocyanate group-terminated urethane prepolymer (solid content) is, for example, 84 or more, preferably 150 or more, and more preferably 168 or more. The isocyanate group equivalent of the isocyanate group-terminated urethane prepolymer (solid content) is, for example, 3500 or less, preferably 2800 or less, and more preferably 2335 or less. The isocyanate group equivalent is synonymous with the amine equivalent, and can be determined by Method A or B of JIS K 1603-1 (2007).

[0049] The isocyanate group content (isocyanate group content, NCO%) of the isocyanate group-terminated urethane prepolymer (solid content) is, for example, 1.2 mass% or more, preferably 1.5 mass% or more, more preferably 1.8 mass% or more, even more preferably 2.0 mass% or more, and particularly preferably 2.1 mass% or more. The isocyanate group content of the isocyanate group-terminated urethane prepolymer (solid content) is, for example, 50 mass% or less, preferably 28 mass% or less, more preferably 25 mass% or less, even more preferably 10 mass% or less, and particularly preferably 6 mass% or less.

[0050] The viscosity of the solid content of the isocyanate-terminated urethane prepolymer at 25° C. is, for example, 1000 mPa·s or more, preferably 5000 mPa·s or more. The viscosity of the solid content of the isocyanate-terminated urethane prepolymer at 25° C. is, for example, 200,000 mPa·s or less, preferably 100,000 mPa·s or less. The viscosity is measured using a B-type viscometer (the same applies below).

[0051] The polyisocyanate component may contain other polyisocyanates as optional components. The other polyisocyanates are isocyanate compounds other than the above-mentioned isocyanate group-terminated urethane prepolymers.

[0052] Other polyisocyanates include, for example, polyisocyanate monomers and polyisocyanate derivatives.

[0053] Examples of the polyisocyanate monomer include aromatic polyisocyanate monomers, araliphatic polyisocyanate monomers, alicyclic polyisocyanate monomers, and chain aliphatic polyisocyanate monomers.

[0054] Examples of the aromatic polyisocyanate monomer include the aromatic polyisocyanate monomers described above. Examples of the aromatic aliphatic polyisocyanate monomer include the aromatic aliphatic polyisocyanate monomers described below. Examples of the alicyclic polyisocyanate monomer include the alicyclic polyisocyanate monomers described below. Examples of the linear aliphatic polyisocyanate monomer include ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI) and hexamethylene diisocyanate (HDI).

[0055] The polyisocyanate derivatives include modified products of the above polyisocyanate monomers. Examples of the modified products include polymers, isocyanurate modified products, allophanate modified products, polyol modified products, biuret modified products, urea modified products, oxadiazinetrione modified products, and carbodiimide modified products. These can be used alone or in combination of two or more types.

[0056] As the polyisocyanate derivative, preferably, a derivative of an aromatic polyisocyanate monomer (hereinafter, aromatic polyisocyanate derivative) is used, and more preferably, a carbodiimide-modified product of an aromatic polyisocyanate monomer is used.

[0057] In other words, the polyisocyanate component preferably contains an aromatic polyisocyanate derivative, and more preferably contains a carbodiimide-modified product of an aromatic polyisocyanate monomer.

[0058] The carbodiimide-modified aromatic polyisocyanate monomer is a reaction product of a carbodiimidization reaction of an aromatic polyisocyanate monomer.

[0059] As the aromatic polyisocyanate, preferably, an aromatic diisocyanate is used, and more preferably, diphenylmethane diisocyanate is used.

[0060] The carbodiimidization reaction may be a decarboxylation condensation reaction, for example, in which an aromatic polyisocyanate monomer is heated in the presence of a carbodiimidization catalyst.

[0061] The carbodiimidization catalyst is not particularly limited, but may be, for example, a trialkyl phosphate ester compound, a phosphorene oxide compound, a phosphorene sulfide compound, a phosphine oxide compound, or a phosphine compound. The mixing ratio of the carbodiimidization catalyst is appropriately set. In addition, the reaction conditions in the carbodiimidization reaction are appropriately set according to the type of aromatic polyisocyanate monomer and the type of catalyst. If necessary, the aromatic polyisocyanate monomer may be subjected to a carbodiimidization reaction in the presence of the above-mentioned organic solvent.

[0062] The carbodiimidization reaction causes decarboxylation and condensation of the aromatic polyisocyanate monomer to generate a carbodiimide group, resulting in a carbodiimide-modified product of the aromatic polyisocyanate monomer.

[0063] In addition, the carbodiimide modified product of the aromatic polyisocyanate monomer may contain free (unreacted) aromatic polyisocyanate monomer, organic solvent and carbodiimide catalyst as necessary. In addition, the free (unreacted) aromatic polyisocyanate monomer, organic solvent and carbodiimide catalyst may be removed by a known removal means. Examples of the removal means include extraction and distillation.

[0064] In addition, the carbodiimide-modified aromatic polyisocyanate monomer may be a commercially available product, such as Coronate MX (a carbodiimide-modified diphenylmethane diisocyanate, NCO content 29.0% by mass, manufactured by Tosoh Corporation).

[0065] In addition, the optional other polyisocyanate may also be other isocyanate-terminated urethane prepolymers. The other isocyanate-terminated urethane prepolymers are isocyanate-terminated urethane prepolymers other than the isocyanate-terminated urethane prepolymer that is the reaction product of the first raw material polyisocyanate and the first raw material polyol.

[0066] More specifically, other isocyanate group-terminated urethane prepolymers include isocyanate group-terminated urethane prepolymers obtained by using aromatic aliphatic polyisocyanates (hereinafter, isocyanate group-terminated aromatic aliphatic urethane prepolymers), isocyanate group-terminated urethane prepolymers obtained by using alicyclic polyisocyanates (hereinafter, isocyanate group-terminated alicyclic urethane prepolymers), and isocyanate group-terminated urethane prepolymers obtained by using linear aliphatic polyisocyanates (hereinafter, isocyanate group-terminated linear aliphatic urethane prepolymers). These can be used alone or in combination of two or more kinds.

[0067] As the other isocyanate group-terminated urethane prepolymer, preferably, an isocyanate group-terminated aromatic aliphatic urethane prepolymer is used.

[0068] In other words, the polyisocyanate component preferably contains another isocyanate group-terminated urethane prepolymer, and more preferably contains another isocyanate group-terminated araliphatic urethane prepolymer.

[0069] The isocyanate group-terminated aromatic aliphatic urethane prepolymer can be obtained, for example, by reacting an aromatic aliphatic polyisocyanate monomer and / or derivative with the above-mentioned first macropolyol. The aromatic aliphatic polyisocyanate monomer and / or derivative reacts with the first macropolyol so that the isocyanate groups are in excess relative to the hydroxyl groups. In addition, known methods are used for these reactions.

[0070] The other polyisocyanates can be used alone or in combination of two or more kinds. As the other polyisocyanates, preferably, polyisocyanate derivatives and other isocyanate group-terminated urethane prepolymers are used, more preferably, polyisocyanate derivatives are used, further preferably, aromatic polyisocyanate derivatives are used, and particularly preferably, carbodiimide modified products of aromatic polyisocyanate monomers are used.

[0071] In the polyisocyanate component, the ratio of the isocyanate group-terminated urethane prepolymer to other polyisocyanates is appropriately set according to the purpose and use. For example, the ratio of the isocyanate group-terminated urethane prepolymer to the total amount of the isocyanate group-terminated urethane prepolymer and other polyisocyanates is, for example, 30% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more. In addition, the ratio of the isocyanate group-terminated urethane prepolymer is, for example, 100% by mass or less, preferably 90% by mass or less, more preferably 80% by mass or less.

[0072] The proportion of the other polyisocyanates relative to the total amount of the isocyanate group-terminated urethane prepolymer and the other polyisocyanates is, for example, 0% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more.The proportion of the other polyisocyanates is, for example, 70% by mass or less, preferably 60% by mass or less, more preferably 50% by mass or less.

[0073] The viscosity of the solid content of the polyisocyanate component at 25° C. is, for example, 1000 mPa·s or more, preferably 5000 mPa·s or more, and for example, 200,000 mPa·s or less, preferably 100,000 mPa·s or less.

[0074] The polyol component contains, as an essential component, a urethane prepolymer having two or more hydroxyl groups at the molecular terminals (hereinafter referred to as a hydroxyl group-terminated urethane prepolymer).

[0075] The hydroxyl-terminated urethane prepolymer is a reaction product of a second raw material polyisocyanate and a second raw material polyol. The second raw material polyisocyanate and the second raw material polyol react with each other so that the number of isocyanate groups is insufficient relative to the number of hydroxyl groups.

[0076] The second raw material polyisocyanate contains an araliphatic polyisocyanate and / or an alicyclic polyisocyanate, and preferably consists of an araliphatic polyisocyanate and / or an alicyclic polyisocyanate.

[0077] Examples of the araliphatic polyisocyanate include araliphatic polyisocyanate monomers and araliphatic polyisocyanate derivatives.

[0078] Examples of the araliphatic polyisocyanate monomer include araliphatic diisocyanates. Examples of the araliphatic diisocyanates include 1,3-xylylene diisocyanate (1,3-XDI), 1,4-xylylene diisocyanate (1,4-XDI), tetramethyl xylylene diisocyanate, and ω,ω'-diisocyanato-1,4-diethylbenzene. These can be used alone or in combination of two or more kinds.

[0079] The aromatic aliphatic polyisocyanate derivative may be modified in the same manner as the aromatic polyisocyanate derivative. More specifically, the aromatic aliphatic polyisocyanate derivative may be modified in the same manner as the aromatic polyisocyanate derivative. For example, the aromatic aliphatic polyisocyanate derivative may be modified in the same manner as the aromatic polyisocyanate derivative. The ...

[0080] Examples of the alicyclic polyisocyanate include alicyclic polyisocyanate monomers and alicyclic polyisocyanate derivatives.

[0081] Examples of the alicyclic polyisocyanate monomer include alicyclic diisocyanates. Examples of the alicyclic diisocyanates include isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), methylene bis(cyclohexyl isocyanate) (H 12 MDI) and bis(isocyanatomethyl)cyclohexane (H6XDI). These can be used alone or in combination of two or more.

[0082] The alicyclic polyisocyanate derivative may be modified in the same manner as the aromatic polyisocyanate derivative. More specifically, the alicyclic polyisocyanate derivative may be modified in the same manner as the aromatic polyisocyanate derivative. For example, the alicyclic polyisocyanate derivative may be modified in the same manner as the aromatic polyisocyanate derivative. For example, the alicyclic polyisocyanate derivative may be modified in the same manner as the aromatic polyisocyanate derivative. The ...

[0083] These araliphatic polyisocyanates and / or alicyclic polyisocyanates can be used alone or in combination of two or more kinds. From the viewpoint of adhesive properties, the araliphatic polyisocyanates and / or alicyclic polyisocyanates are preferably araliphatic polyisocyanate monomers, more preferably araliphatic diisocyanates, even more preferably xylylene diisocyanate, and particularly preferably 1,3-xylylene diisocyanate. In other words, the araliphatic polyisocyanates are preferably composed of xylylene diisocyanate, more preferably 1,3-xylylene diisocyanate.

[0084] The second raw material polyol contains a macropolyol as an essential component.

[0085] The number average molecular weight of the macropolyol in the second raw material polyol (hereinafter, second macropolyol) is not less than 100. In addition, the number average molecular weight of the second macropolyol is usually not more than 15,000.

[0086] More specifically, the second macro polyol may be, for example, polyether polyol, polyester polyol, polycarbonate polyol, polyurethane polyol, epoxy polyol, vegetable oil polyol, polyolefin polyol, acrylic polyol, or vinyl monomer modified polyol. The second macro polyol may be used alone or in combination of two or more kinds. The second macro polyol may preferably be, for example, polyether polyol, polyester polyol, or polycarbonate polyol.

[0087] Examples of polyether polyols include polyoxyalkylene (C2-3) polyols and polytetramethylene ether polyols, and preferably polyoxyalkylene (C2-3) polyols.

[0088] Polyoxy(C2-3) alkylene polyol is an addition polymer of a known initiator and an alkylene oxide having 2 to 3 carbon atoms. Examples of the initiator include known low molecular weight polyols and known polyamine compounds.

[0089] The alkylene oxide may be an alkylene oxide having 2 to 3 carbon atoms. More specifically, the alkylene oxide may be, for example, ethylene oxide (IUPAC name: oxirane), propylene oxide (1,2-propylene oxide (IUPAC name: methyloxirane)), and triethylene oxide (1,3-propylene oxide). These alkylene oxides may be used alone or in combination of two or more kinds. The alkylene oxide may preferably be ethylene oxide or propylene oxide.

[0090] More specifically, the polyoxyalkylene (C2-3) polyol may be, for example, polyoxyethylene polyol, polyoxypropylene polyol, polyoxytriethylene polyol, or polyoxyethylene-polyoxypropylene polyol (random or block copolymer). The polyoxyalkylene (C2-3) polyol may be used alone or in combination of two or more kinds.

[0091] As the polyoxyalkylene (C2-3) polyol, preferably, polyoxypropylene polyol is used, and more preferably, polyoxypropylene glycol is used.

[0092] As the second macropolyol, more preferably, polyether polyol is used, and further preferably, polyoxy(C2-3) alkylene polyol is used.

[0093] The number average molecular weight of the second macropolyol is, for example, 100 or more, preferably 150 or more, more preferably 180 or more, even more preferably 300 or more, even more preferably 350 or more, and even more preferably 400 or more. The number average molecular weight of the second macropolyol is, for example, 15000 or less, preferably 1000 or less. 0 or less , more preferably 8000 or less, even more preferably 5000 or less, even more preferably 2000 or less, even more preferably 1000 or less, and particularly preferably 700 or less.

[0094] The hydroxyl equivalent of the second macropolyol is, for example, 90 or more, preferably 120 or more, more preferably 150 or more, and even more preferably 200 or more. The hydroxyl equivalent of the second macropolyol is, for example, 1000 or less, preferably 800 or less, more preferably 600 or less, and even more preferably 550 or less.

[0095] The average number of hydroxyl groups of the second macropolyol is, for example, 1.8 or more, preferably 2 or more. The average number of hydroxyl groups of the second macropolyol is, for example, 6 or less, preferably 4 or less, more preferably 3 or less.

[0096] The second raw material polyol may contain a low molecular weight polyol as an optional component. The molecular weight of the low molecular weight polyol in the second raw material polyol (hereinafter, second low molecular weight polyol) is less than 100, preferably 90 or less.

[0097] As the second low molecular weight polyol, among the above-mentioned first low molecular weight polyols, one having a molecular weight of less than 100 is used. The second low molecular weight polyol can be used alone or in combination of two or more kinds. The content ratio of the second low molecular weight polyol is appropriately selected within a range that does not impair the excellent effects of the present invention.

[0098] More specifically, the content of the second low-molecular-weight polyol is, for example, 30 parts by mass or less, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and particularly preferably 0 part by mass, relative to 100 parts by mass of the total amount of the second raw material polyol. That is, from the viewpoint of adhesive strength, the second raw material polyol preferably consists of the second macropolyol.

[0099] The hydroxyl-terminated urethane prepolymer is obtained by reacting the second raw material polyisocyanate with the second raw material polyol by a known method. More specifically, the second raw material polyisocyanate and the second raw material polyol are mixed in a predetermined ratio and subjected to a urethane reaction.

[0100] In the urethanization reaction, the equivalent ratio (OH / NCO) of the hydroxyl groups in the second raw material polyol to the isocyanate groups in the second raw material polyisocyanate is appropriately set depending on the average number of functional groups of the second raw material polyol, etc.

[0101] For example, when the average functionality of the second raw material polyol is 2, the equivalent ratio (OH / NCO) of the hydroxyl groups in the second raw material polyol to the isocyanate groups in the second raw material polyisocyanate exceeds 1, and is preferably 1.1 or more, more preferably 1.3 or more, even more preferably 1.5 or more, and particularly preferably 1.9 or more. In addition, the equivalent ratio (OH / NCO) is, for example, 50 below , preferably 15 or less, more preferably 10 or less, even more preferably 3 or less, and particularly preferably 2.5 or less.

[0102] When the average functionality of the second raw material polyol is 3, the equivalent ratio (OH / NCO) of the hydroxyl groups in the second raw material polyol to the isocyanate groups in the second raw material polyisocyanate exceeds 1, and is preferably 1.1 or more, more preferably 1.3 or more, even more preferably 3 or more, and particularly preferably 3.5 or more. below, It is preferably 15 or less, more preferably 10 or less, even more preferably 5 or less, and particularly preferably 4.5 or less.

[0103] 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 or higher, for example, 120°C or lower, preferably 100°C or lower. The reaction time is, for example, 0.5 hours or higher, preferably 1 hour or higher, for example, 48 hours or lower, preferably 24 hours or lower. 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 (reaction without solvent) is adopted.

[0104] In the urethane reaction, a known urethane catalyst is added as necessary. If necessary, unreacted polyisocyanate is removed by a known method. This produces a hydroxyl-terminated urethane prepolymer.

[0105] As the hydroxyl-terminated urethane prepolymer, preferably, a hydroxyl-terminated urethane prepolymer which is a reaction product of an araliphatic polyisocyanate and a polyether polyol is used, and more preferably, a hydroxyl-terminated urethane prepolymer which is a reaction product of a xylylene diisocyanate and a polyether polyol is used.

[0106] The number average molecular weight of the hydroxyl group-terminated urethane prepolymer is, for example, 300 or more, preferably 350 or more, and more preferably 400 or more. The number average molecular weight of the hydroxyl group-terminated urethane prepolymer is, for example, 10,000 or less, preferably 8,000 or less, and more preferably 5,000 or less.

[0107] From the viewpoint of adhesive strength, the hydroxyl equivalent of the hydroxyl-terminated urethane prepolymer is, for example, 150 or more, preferably 190 or more, more preferably 300 or more, and even more preferably 350 or more. The hydroxyl equivalent of the hydroxyl-terminated urethane prepolymer is, for example, 3100 or less, preferably 2100 or less, more preferably 1500, even more preferably 1100 or less, and particularly preferably 1000 or less.

[0108] The average number of hydroxyl groups in the hydroxyl-terminated urethane prepolymer is, for example, 1.8 or more, preferably 2 or more. The average number of hydroxyl groups in the hydroxyl-terminated urethane prepolymer is, for example, 6 or less, preferably 4 or less, more preferably 3 or less.

[0109] In addition, the hydroxyl-terminated urethane prepolymer may contain free (unreacted) second raw material polyol, organic solvent, and urethane catalyst, if necessary. In addition, the free (unreacted) second raw material polyol, organic solvent, and urethane catalyst may be removed from the hydroxyl-terminated urethane prepolymer by a known removal means. Examples of the removal means include extraction and distillation.

[0110] If the polyol component contains the above-mentioned hydroxyl-terminated urethane prepolymer, excellent adhesive properties can be obtained. Furthermore, if the polyol component contains the above-mentioned hydroxyl-terminated urethane prepolymer, excellent pot life and fast curing properties can be obtained, and workability can be improved.

[0111] From the viewpoint of adhesive strength, the content of the hydroxyl-terminated urethane prepolymer is, for example, 1% by mass or more, preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more, based on the total amount of the polyol component. Also, the content of the hydroxyl-terminated urethane prepolymer is, for example, 100% by mass or less, preferably 80% by mass or less, more preferably 50% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less, based on the total amount of the polyol component.

[0112] The polyol component contains a low molecular weight polyol (hereinafter, referred to as a third low molecular weight polyol) as an essential component. The molecular weight of the third low molecular weight polyol is less than 200, preferably 180 or less. Examples of the third low molecular weight polyol include the above-mentioned first low molecular weight polyol. The third low molecular weight polyol can be used alone or in combination of two or more kinds.

[0113] The content of the third low-molecular-weight polyol is, for example, 10 parts by mass or more, preferably 50 parts by mass or more, relative to 100 parts by mass of the hydroxyl-terminated urethane prepolymer. The content of the third low-molecular-weight polyol is, for example, 1000 parts by mass or less, preferably 300 parts by mass or less, relative to 100 parts by mass of the hydroxyl-terminated urethane prepolymer.

[0114] The polyol component may also contain other macropolyols as optional components. The other macropolyols are macropolyols other than the above-mentioned hydroxyl-terminated urethane prepolymers.

[0115] Other macro polyols include, for example, polyether polyols, polyester polyols, polycarbonate polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols and vinyl monomer modified polyols.These macro polyols can be used alone or in combination of two or more kinds.Preferably, the macro polyol is polyether polyol.

[0116] The polyether polyol may be the polyether polyol described above as the second raw material polyol. More specifically, the polyether polyol may be, for example, polyoxyalkylene (C2-3) polyol and polytetramethylene ether polyol, and preferably polyoxyalkylene (C2-3) polyol.

[0117] More specifically, the polyoxyalkylene (C2-3) polyol may be, for example, polyoxyethylene polyol, polyoxypropylene polyol, polyoxytriethylene polyol, or polyoxyethylene-polyoxypropylene polyol (random or block copolymer). The polyoxyalkylene (C2-3) polyol may be used alone or in combination of two or more kinds.

[0118] From the viewpoint of adhesive strength, the number average molecular weight of the other macropolyol is, for example, 500 or more, preferably 1000 or more, more preferably 1500 or more. From the viewpoint of adhesive strength, the number average molecular weight of the macropolyol is, for example, 10000 or less, more preferably 7500 or less, more preferably 5000 or less.

[0119] The hydroxyl equivalent of the other macropolyol is, for example, 150 or more, preferably 200 or more. The hydroxyl equivalent of the other macropolyol is, for example, 10,000 or less, preferably 8,000 or less.

[0120] From the viewpoint of crosslink density and adhesive strength, the average number of hydroxyl groups of the other macropolyol is 1.9 or more, preferably 2 or more, more preferably 2.3 or more, even more preferably 2.5 or more, and particularly preferably 3 or more. From the viewpoint of adhesive strength, the average number of hydroxyl groups of the other macropolyol is, for example, 4 or less, preferably 3.5 or less.

[0121] That is, the polyol component preferably contains another macropolyol having an average number of 3 or more hydroxyl groups, and more preferably contains a polyether polyol having an average number of 3 or more hydroxyl groups.

[0122] In addition, when the polyol component contains other macropolyols, the content ratio of the other macropolyols is, for example, 100 parts by mass or more, preferably 500 parts by mass or more, relative to 100 parts by mass of the hydroxyl-terminated urethane prepolymer. In addition, the content ratio of the other macropolyols is, for example, 5000 parts by mass or less, preferably 2000 parts by mass or less, relative to 100 parts by mass of the hydroxyl-terminated urethane prepolymer.

[0123] 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.

[0124] The additives are, for example, , PoThe additive may be added to a mixture of the reisocyanate component and the polyol component (for example, a one-liquid curing adhesive, etc.). The additive may be, for example, contained in the base agent described below, or in the curing agent described below, or may be contained in both of them.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] As described above, the structural polyurethane adhesive is preferably a two-component curing adhesive having a base agent containing a polyisocyanate component and a curing agent containing a polyol component. A two-component curing adhesive is a resin composition kit (two-component kit) in which a base agent and a curing agent, which are prepared separately, are blended (mixed) at the time of use to form a cured product. 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.

[0129] In the structural polyurethane adhesive, the polyisocyanate component includes an isocyanate-terminated urethane prepolymer that is a reaction product of a first raw material polyisocyanate including an aromatic polyisocyanate and a first raw material polyol including a macropolyol (first macropolyol), and the polyol component includes an aromatic aliphatic polyisocyanate. and / or alicyclic polyisocyanatesThe structural polyurethane contains a hydroxyl-terminated urethane prepolymer, which is a reaction product of a second raw material polyisocyanate containing the above, a second raw material polyol containing a macropolyol (second macropolyol), and a low molecular weight polyol (third low molecular weight polyol). Therefore, the structural polyurethane has excellent adhesive properties.

[0130] Therefore, the structural polyurethane adhesive is suitable for use in structures (such as automobiles and buildings) that are made up of a plurality of components, for example, to bond the components together. Examples of structures include buildings, automobiles, transportation equipment, and ships.

[0131] 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.

[0132] From the viewpoint of workability, the viscosity of the mixture containing the polyisocyanate component and the polyol component at 25° C. is, for example, 100 mPa·s or more, preferably 300 mPa·s or more. Also, the viscosity of the mixture at 25° C. is, for example, 500,000 mPa·s or less, preferably 100,000 mPa·s or less, more preferably 50,000 mPa·s or less.

[0133] The curing conditions and curing conditions are appropriately set. More specifically, the curing temperature is, for example, 10° C. or higher, preferably 20° C. or higher. The curing temperature is, for example, 80° C. or lower, preferably 60° C. or lower. The curing time is, for example, 0.5 hours or higher, preferably 1 hour or higher. The curing time is, for example, 10 hours or lower, preferably 5 hours or lower. The curing temperature is, for example, 10° C. or higher, preferably 20° C. or higher. The curing temperature is, for example, 80° C. or lower, preferably 70° C. or lower. The curing time is, for example, 1 hour or higher, preferably 2 hours or higher. The curing time is, for example, 2 weeks or lower, preferably 1 week or lower.

[0134] This allows the structural polyurethane adhesive to harden and bond the various components well. EXAMPLES

[0135] 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".

[0136] Polyisocyanate component (Preparation Example 1) Isocyanate-Terminated Urethane Prepolymer 289 parts by mass of Actocol DL4000 (trade name, polyether polyol with number average molecular weight of 4000 and average number of hydroxyl groups of 2, manufactured by Mitsui Chemicals) and 578 parts by mass of Actocol T-5000 (trade name, polyether polyol with number average molecular weight of 5000 and average number of hydroxyl groups of 3, manufactured by Mitsui Chemicals) as the first raw material polyol were mixed with 133 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI) as the first raw material polyisocyanate. The equivalent ratio (NCO / OH) at this time was 2.16. As a result, an isocyanate group-terminated urethane prepolymer (MDI prepolymer) was obtained. The solid content concentration of the MDI prepolymer was 100%, and the isocyanate group content was 2.33% by mass.

[0137] (Preparation Example 2) Aromatic polyisocyanate derivative As an aromatic polyisocyanate derivative, Coronate MX (a carbodiimide-modified diphenylmethane diisocyanate with an NCO content of 29.0% by mass, manufactured by Tosoh Corporation) was prepared. Hereinafter, the solid content in Coronate MX is referred to as MDI carbodiimide.

[0138] (Preparation Example 3) Other isocyanate-terminated urethane prepolymers 264.0 parts by mass of Actocol D-400 (trade name, polyether polyol with number average molecular weight of 400 and average number of hydroxyl groups of 2, manufactured by Mitsui Chemicals) and 736.0 parts by mass of 1,3-xylylene diisocyanate (XDI) were mixed. The equivalent ratio (NCO / OH) at this time was 6.0. The mixture obtained was then stirred in a nitrogen stream at 60°C for 1 hour, and further stirred at 70°C for 4 hours to cause a urethane reaction. Furthermore, the reaction product was subjected to thin-film distillation (wall temperature 145-155°C, vacuum degree 100 Pa or less, flow rate 3-5 g / min, cooling water temperature 10°C). death The unreacted 1,3-xylylene diisocyanate (monomer) was distilled off. This resulted in an isocyanate group-terminated urethane prepolymer (XDI prepolymer). The solids concentration of the XDI prepolymer was 100%, and the isocyanate group content was 10.5% by mass.

[0139] Polyol component (Preparation Example 4) Hydroxyl-terminated urethane prepolymer (D-400 / XDI) 813.01 parts by mass of Actocol D-400 (trade name, polyether polyol with number average molecular weight of 400 and average number of hydroxyl groups of 2, manufactured by Mitsui Chemicals) as the second raw material polyol and 186.99 parts by mass of 1,3-xylylene diisocyanate (XDI) as the second raw material polyisocyanate were mixed. The equivalent ratio (OH / NCO) at this time was 2.02. Next, the obtained mixture was stirred in a nitrogen gas flow at 60°C for 1 hour, and further stirred at 70°C for 6 hours to cause a urethane reaction. As a result, a hydroxyl group-terminated urethane prepolymer was obtained. The hydroxyl value of the hydroxyl-terminated urethane prepolymer was 493, the solids concentration was 100%, and the viscosity at 25°C was 4500 mPa·s.

[0140] (Preparation Example 5) Hydroxyl-terminated urethane prepolymer (T-700 / XDI) 1,3-xylylene diisocyanate (XDI) was used as the second raw material polyisocyanate, and Actocol T-700 (trade name, polyether polyol with number average molecular weight of 700 and average number of hydroxyl groups of 3, manufactured by Mitsui Chemicals) was used as the second raw material polyol, and the equivalent ratio ( OH / NCO The mixture was reacted at 80°C for 1 hour, and then subjected to a urethane reaction at 90°C for 4 hours.

[0141] A hydroxyl-terminated urethane prepolymer was obtained in the same manner as in Preparation Example 4. The hydroxyl-terminated urethane prepolymer had a hydroxyl value of 380, a solids concentration of 100%, and a viscosity at 25°C of 7400 mPa·s.

[0142] (Preparation Example 6) Hydroxyl-terminated urethane prepolymer (D-1000 / MDI) 1,3-xylylene diisocyanate (XDI) was used as the second raw material polyisocyanate, and Actocol D-1000 (product name, polyether polyol with number average molecular weight of 1000 and average number of hydroxyl groups of 2, manufactured by Mitsui Chemicals) was used as the second raw material polyol. OH / NCO The mixture was reacted at 80°C for 3 hours, and then subjected to a urethane reaction at 90°C for 5 hours.

[0143] A hydroxyl-terminated urethane prepolymer was obtained in the same manner as in Preparation Example 4. The hydroxyl-terminated urethane prepolymer had a hydroxyl value of 1093, a solids concentration of 100%, and a viscosity at 25°C of 1900 mPa·s.

[0144] (Preparation Example 7) Hydroxyl-terminated urethane prepolymer (D-400 / MDI) As the second raw material polyisocyanate, 4,4'-diphenylmethane diisocyanate (MDI) was used, and as the second raw material polyol, Actocol D-400 (product name, polyether polyol with number average molecular weight of 400 and average number of hydroxyl groups of 2, manufactured by Mitsui Chemicals) was used, with an equivalent ratio (OH / NCO) of 2.02. These were subjected to a urethane reaction at 60°C for 7 hours.

[0145] A hydroxyl-terminated urethane prepolymer was obtained in the same manner as in Preparation Example 4. The hydroxyl-terminated urethane prepolymer had a hydroxyl value of 524, a solids concentration of 100%, and a viscosity at 25°C of 73,600 mPa·s.

[0146] (Preparation Example 8) Hydroxyl-terminated urethane prepolymer (D-400 / HDI) Hexamethylene diisocyanate (HDI) was used as the second raw material polyisocyanate, and Actocol D-400 (product name, polyether polyol with number average molecular weight of 400 and average number of hydroxyl groups of 2, manufactured by Mitsui Chemicals) was used as the second raw material polyol, with an equivalent ratio (OH / NCO) of 2.02. These were subjected to a urethane reaction at 110°C for 18 hours.

[0147] A hydroxyl-terminated urethane prepolymer was obtained in the same manner as in Preparation Example 4. The hydroxyl-terminated urethane prepolymer had a hydroxyl value of 484, a solids concentration of 100%, and a viscosity at 25°C of 2700 mPa·s.

[0148] (Preparation Example 9) Macropolyol As the macropolyol, Actocol D-1000 (product name, polyether polyol having a number average molecular weight of 1000 and an average number of hydroxyl groups of 2, manufactured by Mitsui Chemicals) was prepared.

[0149] (Preparation Example 10) Macropolyol As the macropolyol, Actocol EP-330N (polyoxyalkylene polyol (propylene oxide-ethylene oxide block copolymer) having an average functionality of 3, number average molecular weight of 5000, manufactured by Mitsui Chemicals, Inc.) was prepared.

[0150] (Preparation Example 11) Low Molecular Weight Polyol As the low molecular weight polyol, 1,4-butanediol (1,4-BD) was prepared.

[0151] Examples 1 to 12 and Comparative Examples 1 to 5 In addition, the polyisocyanate component and the polyol component were prepared by mixing each component according to the formulation (solid content) shown in Tables 1 to 3. The catalyst (DABCO 33-LV) was added to the polyol component at 860 ppm. This resulted in a structural polyurethane adhesive including the polyisocyanate component and the polyol component.

[0152] Examples 2 to 3 are examples of formulations in which the type of hydroxyl-terminated urethane prepolymer is changed from Example 1. Examples 4 to 7 and Examples 11 to 12 are examples of formulations in which the amount of hydroxyl-terminated urethane prepolymer is changed from Example 1. Example 8 is an example of a formulation in which macropolyol is not blended from Examples 1 to 3. Example 9 is an example of a formulation in which MDI carbodiimide is not blended from Example 1. Example 10 is an example of a formulation in which MDI carbodiimide is not blended from Example 1, and another isocyanate-terminated urethane prepolymer is blended.

[0153] Comparative Example 1 is a comparative example of a formulation in which a hydroxyl-terminated urethane prepolymer is not blended, as compared to Example 1. Comparative Examples 2 and 3 are comparative examples of formulations in which the type of hydroxyl-terminated urethane prepolymer is changed, as compared to Example 1. Comparative Example 4 is a comparative example of a formulation in which the hydroxyl-terminated urethane prepolymer is changed to a macropolyol, as compared to Example 1.

[0154] Comparative Example 5 is a comparative example of a formulation in which the hydroxyl group-terminated urethane prepolymer is not blended in contrast to Example 9.

[0155] (evaluation) 1. Adhesion test (PP / SPCC) A polypropylene plate (J707G, Prime Polymer (PP)) was cut to a width of 25 mm to prepare a test piece. This was corona-treated just before preparing the adhesion test specimen, and the wettability (JISK 6768 (1999)) was adjusted to 40 dyn / cm or more, and this was used as adherend 1.

[0156] On the other hand, a cold-rolled steel plate (SPCC) was cut to a width of 25 mm and cathodic electrocoated (ED) to prepare an ED-SPCC plate (JIS G 3141 (SPCC, SD), test piece manufactured). Next, the surface of the SPCC was degreased and washed with isopropyl alcohol, and then dried. This was used as the adherend 2.

[0157] The polyisocyanate component and the polyol component were mixed at an equivalent ratio (NCO / OH) of 1.05. Next, glass beads (ASGB-60, AS ONE, 0.250 to 0.355 mm) were added to the resulting mixture to adjust the layer thickness. The amount of glass beads added was adjusted to 1% by mass relative to the total amount of the polyisocyanate component, the polyol component, and the glass beads.

[0158] The mixture was then applied to the adherend 1, and the adherend 1 and the adherend 2 were attached together so that the adhesive area was 25 mm × 12.5 mm and the adhesive layer thickness was 0.3 mm, cured at 25°C for 1 hour, and aged at room temperature (18 to 28°C, 45 to 55% RH) for 1 week. This resulted in an adhesion test specimen (hereinafter, test plate).

[0159] The shear adhesive strength (hereinafter, adhesive strength) [MPa] between the adherend 1 and the adherend 2 was measured using a tensile tester (U-4410, manufactured by Orientec Co., Ltd.) at a tensile speed of 50 mm / min.

[0160] [Table 1]

[0161] [Table 2]

[0162] [Table 3]

[0163] 2.Adhesion test (CFRP / SPCC) A CFRP (matte) 2.0 x 25 x 100 mm made by Standard Test Piece was prepared. RP The surface was degreased and cleaned with isopropyl alcohol, and then dried. This was used as adherend 1. Other than that, the adhesive strength was measured for Examples 1 to 3 and Comparative Example 4 in the same manner as in the above adhesion test (PP / SPCC).

[0164] [Table 4]

[0165] 3. Workability For Examples 1 to 3 and Comparative Example 4, the polyisocyanate component and the polyol component were mixed at an equivalent ratio (NCO / OH) of 1.05. The mixture was applied to an acrylic plate to a thickness of 1 mm. The solidification time and pot life were measured using a drying time recorder (Paint Drying Time Meter II, manufactured by Daiyu Kizai Co., Ltd.).

[0166] The solidification time indicates the time when the needle of the drying time recorder reaches the top of the coating film. The pot life is the time when the coating film is backfilled after the needle has passed. The ratio of solidification to pot life (solidification time / pot life) was then calculated. The smaller these ratios (solidification time / pot life) are, the longer the pot life is and the shorter the solidification time is, which indicates superior workability.

[0167] [Table 5]

[0168] The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as being limited. Modifications of the present invention that are obvious to those skilled in the art are included in the scope of the following claims. [Industrial Applicability]

[0169] The structural polyurethane adhesive of the present invention is suitable for use in structures made up of a plurality of members for bonding these members together.

Claims

1. Contains a polyisocyanate component and a polyol component, The polyisocyanate component is The present invention comprises an isocyanate-terminated urethane prepolymer which is a reaction product of a first raw material polyisocyanate containing an aromatic polyisocyanate and a first raw material polyol containing a macropolyol, The polyol component is a hydroxyl-terminated urethane prepolymer which is a reaction product of a second raw material polyisocyanate containing an araliphatic polyisocyanate and / or an alicyclic polyisocyanate and a second raw material polyol containing a macropolyol; Low molecular weight polyol A structural polyurethane adhesive comprising:

2. 2. The structural polyurethane adhesive according to claim 1, wherein a ratio of the hydroxyl group-terminated urethane prepolymer to a total amount of the polyol component is 2% by mass or more and 30% by mass or less.

3. The polyisocyanate component is The structural polyurethane adhesive according to claim 1 , further comprising a carbodiimide-modified aromatic polyisocyanate monomer.

4. The polyol component is The structural polyurethane adhesive according to claim 1 , further comprising a polyether polyol having an average number of 3 or more hydroxyl groups.

5. 10. The structural polyurethane adhesive of claim 1 , wherein said first raw polyisocyanate comprises diphenylmethane diisocyanate.

6. 10. The structural polyurethane adhesive of claim 1 , wherein said second raw material polyisocyanate comprises xylylene diisocyanate.

7. 2. The structural polyurethane adhesive according to claim 1, wherein the hydroxyl equivalent of the hydroxyl-terminated urethane prepolymer is 550 or less.

8. The structural polyurethane adhesive according to claim 1 , which is a two-component curing adhesive comprising a base agent containing the polyisocyanate component and a curing agent containing the polyol component.

9. 10. The structural polyurethane adhesive of claim 1 which is a solventless adhesive.

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