Method for producing isocyanate composition, method for producing structural polyurethane adhesive, and structural polyurethane adhesive

Abstract

To provide an isocyanate composition production method that produces an isocyanate composition for producing a structural polyurethane adhesive with superior adhesive strength, a structural polyurethane adhesive production method that produces a structural polyurethane adhesive using the isocyanate composition, and a structural polyurethane adhesive.SOLUTION: An isocyanate composition production method includes: a first step of reacting an additive raw material polyisocyanate and an additive raw material polyol in a predetermined ratio to form a reaction solution containing an alcohol adduct of polyisocyanate; a second step of separating the unreacted additive raw material polyisocyanate from the reaction solution to prepare an alcohol adduct of polyisocyanate; and a third step of mixing the alcohol adduct of polyisocyanate with an isocyanate-terminated prepolymer at 80°C or more and 170°C or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing an isocyanate composition, a method for producing a structural polyurethane adhesive, and a structural polyurethane adhesive. [Background technology]

[0002] 2. Description of the Related Art Structural adhesives used in structures (such as automobiles and buildings) that are made up of a plurality of members and the like for bonding the members together have been conventionally known.

[0003] As a structural adhesive, for example, a two-liquid urethane adhesive composition containing a polyisocyanate component and a polyol component is known.

[0004] As such a structural adhesive, for example, a structural polyurethane adhesive has been proposed that contains a polyisocyanate component containing an isocyanate-terminated urethane prepolymer obtained using diphenylmethane diisocyanate and a polyol derivative (alcohol adduct) of xylylene diisocyanate, and a polyol component (see, for example, Example 9 of Patent Document 1). In addition, the polyisocyanate component of such a structural adhesive is produced by first removing the solvent from the polyol derivative (alcohol adduct) of xylylene diisocyanate using an evaporator, and then mixing it with the isocyanate-terminated urethane prepolymer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2021 / 085435 Brochure Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, structural adhesives are required to have even greater adhesive strength.

[0007] The present invention provides a method for producing an isocyanate composition for producing an isocyanate composition for producing a structural polyurethane adhesive having excellent adhesive strength, a method for producing a structural polyurethane adhesive using the isocyanate composition, and a structural polyurethane adhesive. [Means for solving the problem]

[0008] The present invention [1] is a method for producing an isocyanate composition comprising an isocyanate group-terminated prepolymer and an alcohol adduct of a polyisocyanate, the isocyanate group-terminated prepolymer being a reaction product of a prepolymer raw material polyisocyanate containing an aromatic polyisocyanate and a prepolymer raw material polyol, the polyisocyanate alcohol adduct being a reaction product of an adduct raw material polyisocyanate and an adduct raw material polyol containing a trifunctional or higher alcohol, the method for producing the isocyanate composition comprising the steps of: The method for producing an isocyanate composition includes a first step of reacting a polyol with the polyisocyanate such that the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group in the adduct raw material polyol to the hydroxyl group in the adduct raw material polyol is 4.0 or more and 7.0 or less to obtain a reaction liquid containing an alcohol adduct of the polyisocyanate; a second step of separating unreacted adduct raw material polyisocyanate from the reaction liquid to obtain the alcohol adduct of the polyisocyanate; and a third step of mixing the alcohol adduct of the polyisocyanate and the isocyanate group-terminated prepolymer at 80° C. or more and 170° C. or less.

[0009] The present invention [2] is a method for producing an isocyanate composition comprising an isocyanate group-terminated prepolymer, an alcohol adduct of a polyisocyanate, and an additive, wherein the isocyanate group-terminated prepolymer is a reaction product of a prepolymer raw material polyisocyanate containing an aromatic polyisocyanate and a prepolymer raw material polyol, and the alcohol adduct of the polyisocyanate is a reaction product of an adduct raw material polyisocyanate and an adduct raw material polyol containing a trifunctional or higher alcohol, and the method for producing the isocyanate composition comprises the steps of: reacting the adduct raw material polyisocyanate and the adduct raw material polyol with the adduct raw material polyisocyanate and the adduct raw material polyol, a fourth step of reacting the adduct starting polyisocyanate with an alcohol adduct of the polyisocyanate so that the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate groups in the adduct starting polyisocyanate to the hydroxyl groups in the adduct starting polyol is 4.0 or more and 7.0 or less to obtain a reaction liquid containing the alcohol adduct of the polyisocyanate; a fifth step of separating unreacted adduct starting polyisocyanate from the reaction liquid to obtain the alcohol adduct of the polyisocyanate; a sixth step of mixing the alcohol adduct of the polyisocyanate and additives at 80° C. or more and 170° C. or less to obtain a mixed liquid; and a seventh step of mixing the mixed liquid and the isocyanate group-terminated prepolymer.

[0010] The present invention [3] includes the method for producing an isocyanate composition according to the above [1], wherein in the second step, separation is performed by distillation at a distillation temperature of 80°C or higher and 170°C or lower, and in the third step, the alcohol adduct of the polyisocyanate heated by the distillation is mixed with the isocyanate group-terminated prepolymer.

[0011] The present invention [4] includes the method for producing an isocyanate composition described in the above [2], wherein in the fifth step, separation is performed by distillation at a distillation temperature of 80°C or more and 170°C or less, and in the sixth step, the alcohol adduct of the polyisocyanate heated by the distillation is mixed with an additive to obtain a mixed liquid.

[0012] The present invention [5] includes the method for producing an isocyanate composition according to the above [2], in which the additive is a plasticizer.

[0013] The present invention [6] includes the method for producing an isocyanate composition according to any one of the above [1] to [5], in which the adduct raw material polyisocyanate is an aliphatic polyisocyanate.

[0014] The present invention [7] includes the method for producing an isocyanate composition according to any one of the above [1] to [6], wherein the tri- or higher functional alcohol is trimethylolpropane.

[0015] The present invention [8] includes the method for producing an isocyanate composition according to any one of the above [1] to [7], wherein the isocyanate composition further contains another polyisocyanate, and the other polyisocyanate contains liquid diphenylmethane diisocyanate.

[0016] The present invention [9] includes the method for producing an isocyanate composition according to any one of the above [1] to [8], wherein the prepolymer raw material polyol contains an ethylene oxide adduct of polyoxypropylene glycol.

[0017] The present invention

[10] includes a method for producing a structural polyurethane adhesive, which comprises mixing an isocyanate composition produced by the method for producing an isocyanate composition described in any one of the above [1] to [9] with a polyol composition.

[0018] The present invention

[11] is a structural polyurethane adhesive comprising an isocyanate composition and a polyol composition and substantially no organic solvent, wherein the isocyanate composition comprises an isocyanate-terminated prepolymer and an alcohol adduct of a polyisocyanate, the isocyanate-terminated prepolymer being a reaction product of a prepolymer raw material polyisocyanate containing an aromatic polyisocyanate and a prepolymer raw material polyol, and the alcohol adduct of the polyisocyanate being a reaction product of an adduct raw material polyisocyanate and an adduct raw material polyol containing a tri- or higher functional alcohol.

[0019] The present invention

[12] is a structural polyurethane adhesive comprising an isocyanate composition and a polyol composition and substantially no organic solvent, wherein the isocyanate composition comprises an isocyanate-terminated prepolymer, an alcohol adduct of a polyisocyanate, and an additive, the isocyanate-terminated prepolymer is a reaction product of a prepolymer raw material polyisocyanate containing an aromatic polyisocyanate and a prepolymer raw material polyol, and the alcohol adduct of the polyisocyanate is a reaction product of an adduct raw material polyisocyanate and an adduct raw material polyol containing a tri- or higher functional alcohol. Effect of the Invention

[0020] The method for producing an isocyanate composition of the present invention includes a third step of mixing an alcohol adduct of polyisocyanate and an isocyanate-terminated prepolymer at 80° C. or higher and 170° C. or a sixth step of mixing an alcohol adduct of polyisocyanate and an additive at 80° C. or higher and 170° C. or lower to obtain a mixed liquid. Therefore, an isocyanate composition for producing a structural polyurethane adhesive having excellent adhesive strength can be produced.

[0021] The method for producing a structural polyurethane adhesive of the present invention uses an isocyanate composition produced by the method for producing an isocyanate composition of the present invention, and therefore a structural polyurethane adhesive having excellent adhesive strength can be produced.

[0022] The structural polyurethane adhesive of the present invention contains substantially no organic solvents, and therefore has excellent adhesive strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 1. First Invention The first invention is a method for producing an isocyanate composition containing an isocyanate group-terminated prepolymer and an alcohol adduct of polyisocyanate, and includes a first step of reacting an adduct raw material polyisocyanate and an adduct raw material polyol so that the equivalent ratio (isocyanate groups / hydroxyl groups) of the isocyanate groups in the adduct raw material polyisocyanate to the hydroxyl groups in the adduct raw material polyol is 4.0 or more and 7.0 or less to obtain a reaction liquid containing the alcohol adduct of polyisocyanate, a second step of separating unreacted adduct raw material polyisocyanate from the reaction liquid to obtain the alcohol adduct of polyisocyanate, and a third step of mixing the alcohol adduct of polyisocyanate and the isocyanate group-terminated prepolymer at 80°C or more and 170°C or less.

[0024] <1st process> In the first step, an adduct raw material polyisocyanate and an adduct raw material polyol are reacted in a predetermined ratio to obtain a reaction liquid containing an alcohol adduct of a polyisocyanate.

[0025] (Polyisocyanate as adduct raw material) Examples of the adduct raw material polyisocyanate include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and araliphatic polyisocyanates.

[0026] Examples of the aliphatic polyisocyanate include aliphatic diisocyanate. Examples of the aliphatic diisocyanate include 1,6-hexamethylene diisocyanate (1,6-HDI), 1,5-pentamethylene diisocyanate (1,5-PDI), tetramethylene diisocyanate, trimethylene diisocyanate, 1,2-, 2,3- or 1,3-butylene diisocyanate, and 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate. Examples of the aliphatic polyisocyanate include 1,6-HDI and 1,5-PDI.

[0027] Examples of alicyclic polyisocyanates include alicyclic diisocyanates. Examples of alicyclic diisocyanates include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 4,4'-, 2,4'- or 2,2'-methylenebis(cyclohexyl isocyanate) or mixtures thereof (H 12 MDI), 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or mixtures thereof (H6XDI), bis(isocyanatomethyl)norbornane (NBDI), 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, and methyl-2,6-cyclohexane diisocyanate.

[0028] Examples of aromatic polyisocyanates include aromatic diisocyanates. Examples of aromatic diisocyanates include 4,4'-, 2,4'- or 2,2'-diphenylmethane diisocyanate or mixtures thereof (MDI), 2,4- or 2,6-tolylene diisocyanate or mixtures thereof (TDI), o-tolidine diisocyanate, 1,5-naphthalene diisocyanate (NDI), m- or p-phenylene diisocyanate or mixtures thereof, 4,4'-diphenyl diisocyanate, and 4,4'-diphenyl ether diisocyanate.

[0029] The aromatic aliphatic polyisocyanate may, for example, be an aromatic aliphatic diisocyanate. The aromatic aliphatic diisocyanate may, for example, be xylylene diisocyanate (1,2-, 1,3-, or 1,4-xylylene diisocyanate or a mixture thereof) (XDI), 1,3-, or 1,4-tetramethyl xylylene diisocyanate or a mixture thereof (TMXDI), and ω,ω′-diisocyanate-1,4-diethylbenzene. The aromatic aliphatic polyisocyanate may, for example, be XDI.

[0030] The polyisocyanate as the raw material for the adduct includes the above-mentioned polyisocyanate derivatives.

[0031] Examples of the polyisocyanate derivatives include the above-mentioned polyisocyanate polymers, allophanate derivatives, polyol derivatives, biuret derivatives, urea derivatives, oxadiazinetrione derivatives, carbodiimide derivatives, uretdione derivatives, and uretonimine derivatives.

[0032] Examples of polyisocyanate derivatives include polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI, polynuclear-containing diphenylmethane diisocyanate) and carbodiimide-modified polymethylene polyphenyl polyisocyanate.

[0033] The adduct raw material polyisocyanate preferably includes an aliphatic polyisocyanate and an araliphatic polyisocyanate. That is, the adduct raw material polyisocyanate preferably includes an aliphatic polyisocyanate and / or an araliphatic polyisocyanate.

[0034] Moreover, from the viewpoint of improving adhesive strength, the adduct raw material polyisocyanate is more preferably an aliphatic polyisocyanate. That is, the adduct raw material polyisocyanate more preferably contains an aliphatic polyisocyanate. The adduct raw material polyisocyanate is further preferably composed of an aliphatic polyisocyanate.

[0035] The polyisocyanates used as raw materials for the adduct can be used alone or in combination of two or more kinds.

[0036] (Adduct raw material polyol) The adduct raw material polyol contains an alcohol having three or more functional groups.

[0037] Examples of the trifunctional or higher alcohol include trihydric alcohol and tetrahydric alcohol. Examples of the trihydric alcohol include glycerin, trimethylolpropane, and triisopropanolamine. Examples of the tetrahydric alcohol include tetramethylolmethane (pentaerythritol) and diglycerin.

[0038] As the trifunctional or higher alcohol, preferably, trihydric alcohol is used. As the trifunctional or higher alcohol, from the viewpoint of improving adhesive strength, more preferably, trimethylolpropane is used. That is, the trifunctional or higher alcohol more preferably includes trimethylolpropane. The trifunctional or higher alcohol further preferably consists of trimethylolpropane.

[0039] The trifunctional or higher alcohols can be used alone or in combination of two or more kinds.

[0040] The adduct raw material polyol may also contain a dihydric alcohol, such as a linear dihydric alcohol or a branched dihydric alcohol.

[0041] Examples of the linear dihydric alcohol include linear dihydric alcohols having from 2 to 6 carbon atoms. Examples of the linear dihydric alcohols having from 2 to 6 carbon atoms include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0042] Examples of the branched dihydric alcohol include branched dihydric alcohols having from 3 to 6 carbon atoms. Examples of the branched dihydric alcohols having from 3 to 6 carbon atoms include 1,2-propanediol, 1,3-butanediol, 1,2-butanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol.

[0043] As the dihydric alcohol, preferably, a branched dihydric alcohol is used, and more preferably, 1,3-butanediol is used.

[0044] The dihydric alcohols can be used alone or in combination of two or more kinds.

[0045] When the adduct raw material polyol contains a dihydric alcohol, the blending ratio of the dihydric alcohol relative to the adduct raw material polyol is, for example, 1 mass% or more, preferably 5 mass% or more, more preferably 10 mass% or more, and for example, 20 mass% or less, preferably 15 mass% or less.

[0046] Moreover, from the viewpoint of improving adhesive strength, the adduct raw material polyol preferably does not contain a dihydric alcohol and is made of a tri- or higher functional alcohol.

[0047] (Reaction of Adduct Raw Material Polyisocyanate and Adduct Raw Material Polyol) In the first step, an adduct raw material polyisocyanate and an adduct raw material polyol are reacted to obtain a reaction liquid containing an alcohol adduct of polyisocyanate (an adduct of polyisocyanate).

[0048] Specifically, the adduct raw material polyisocyanate and the adduct raw material polyol are reacted at a ratio such that the isocyanate groups in the adduct raw material polyisocyanate are in excess relative to the hydroxyl groups in the adduct raw material polyol, more specifically, such that the equivalent ratio of the isocyanate groups in the adduct raw material polyisocyanate to the hydroxyl groups in the adduct raw material polyol (isocyanate groups / hydroxyl groups) is 4.0 or more, preferably 5.0 or more, more preferably 5.5 or more, and 7.0 or less, preferably 6.5 or less, more preferably 6.2 or less.

[0049] When the equivalent ratio is equal to or more than the lower limit, the handling properties and the compatibility with the isocyanate group-terminated prepolymer can be improved.

[0050] On the other hand, if the equivalent ratio is less than the lower limit, the handling properties and the compatibility with the isocyanate group-terminated prepolymer decrease.

[0051] If the equivalent ratio is equal to or less than the upper limit, the unreacted polyisocyanate as the starting material for the adduct can be efficiently separated in the second step (or the fifth step) described below, resulting in improved productivity.

[0052] On the other hand, if the equivalent ratio exceeds the upper limit, the unreacted adduct raw material polyisocyanate becomes excessive in the second step (or the fifth step) described below, and the unreacted adduct raw material polyisocyanate cannot be efficiently separated, resulting in a decrease in productivity.

[0053] As for reaction conditions, the reaction temperature is, for example, 50° C. or more, preferably 70° C. or more, and for example, 100° C. or less, preferably 90° C. or less. The reaction time is, for example, 10 minutes or more, and for example, 600 minutes or less.

[0054] The reaction is carried out until the isocyanate group concentration of the unreacted adduct raw material polyisocyanate becomes, for example, 10% by mass or more, preferably 15% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, and for example, 50% by mass or less.

[0055] This produces a reaction liquid containing an alcohol adduct of polyisocyanate, which is a reaction product of the prepolymer raw material polyisocyanate and the prepolymer raw material polyol. More specifically, a reaction liquid containing an alcohol adduct of polyisocyanate and unreacted adduct raw material polyisocyanate is produced.

[0056] <Second process> In the second step, the unreacted polyisocyanate as the adduct raw material is separated from the reaction liquid obtained in the first step to obtain an alcohol adduct of the polyisocyanate.

[0057] The separation method is not particularly limited, and examples thereof include extraction and distillation. As the separation method, distillation is preferably used.

[0058] A specific example of the distillation is thin film distillation (Smith distillation).

[0059] As for the distillation conditions, the distillation temperature is, for example, 100° C. or more, preferably 120° C. or more, and for example, 170° C. or less, preferably 160° C. or less. The degree of vacuum is, for example, 0.1 kPa or less.

[0060] In this way, the unreacted polyisocyanate as the raw material for the adduct is separated from the reaction liquid to obtain an alcohol adduct of the polyisocyanate. More specifically, the reaction liquid contains the alcohol adduct of the polyisocyanate and does not substantially contain the unreacted polyisocyanate as the raw material for the adduct.

[0061] The reaction liquid being substantially free of unreacted adduct raw material polyisocyanate means that the content of unreacted adduct raw material polyisocyanate relative to the reaction liquid is, for example, 5 mass% or less, preferably 3 mass% or less, more preferably 1 mass% or less, and particularly preferably 0.5 mass% or less.

[0062] <3rd process> In the third step, the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer are mixed at a predetermined temperature.

[0063] To mix the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer, first, the isocyanate-terminated prepolymer is prepared.

[0064] (Isocyanate-terminated prepolymer) The isocyanate-terminated prepolymer is a urethane prepolymer having at least two isocyanate groups at the molecular terminals, and is a reaction product obtained by reacting a prepolymer raw material polyisocyanate with a prepolymer raw material polyol so that there is an excess of isocyanate groups relative to the hydroxyl groups.

[0065] The prepolymer feedstock polyisocyanate includes an aromatic polyisocyanate.

[0066] Examples of the aromatic polyisocyanate include the aromatic polyisocyanates listed in the above-mentioned adduct raw material polyisocyanate. From the viewpoint of improving the adhesive strength, the aromatic polyisocyanate is preferably diphenylmethane diisocyanate. That is, the aromatic polyisocyanate preferably contains diphenylmethane diisocyanate. Moreover, the aromatic polyisocyanate is more preferably composed of diphenylmethane diisocyanate.

[0067] The aromatic polyisocyanates can be used alone or in combination of two or more kinds.

[0068] The prepolymer feedstock polyisocyanate can include polyisocyanates other than aromatic polyisocyanates.

[0069] Examples of polyisocyanates other than aromatic polyisocyanates include the aliphatic polyisocyanates listed above as the raw material polyisocyanates for the adduct, the alicyclic polyisocyanates listed above as the raw material polyisocyanates for the adduct, and the aromatic aliphatic polyisocyanates listed above as the raw material polyisocyanates for the adduct.

[0070] The prepolymer raw material polyisocyanate preferably does not contain any polyisocyanate other than the aromatic polyisocyanate and is composed of the aromatic polyisocyanate.

[0071] The prepolymer raw polyols include macropolyols.

[0072] The macropolyol is a compound having two or more hydroxyl groups and a number average molecular weight of 300 or more, preferably 400 or more, for example, 10,000 or less.

[0073] Examples of the macropolyol include polyether polyol, polyester polyol, polycarbonate polyol, polyurethane polyol, epoxy polyol, vegetable oil polyol, polyolefin polyol, acrylic polyol, and polymer polyol. The macropolyol is preferably polyether polyol.

[0074] Examples of polyether polyols include polyoxy(C2-3) alkylene polyols and polytetramethylene ether polyols.

[0075] Polyoxy(C2-3) alkylene polyol is, for example, an addition polymer of alkylene oxide having 2 to 3 carbon atoms using a low molecular weight polyol described below or a known polyamine compound as an initiator.

[0076] Examples of alkylene oxides include propylene oxide and ethylene oxide. These alkylene oxides can be used alone or in combination of two or more. Polyoxyalkylene polyols include, for example, random and / or block copolymers of propylene oxide and ethylene oxide.

[0077] More specifically, the polyoxy(C2-3)alkylene polyol includes polyalkylene oxides having an average number of functional groups of two and polyalkylene oxides having an average number of functional groups of three.

[0078] Examples of polyalkylene oxides having an average functionality of 2 include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytriethylene glycol, and polyoxyethylene-polyoxypropylene glycol (random or block copolymer). A preferred example of the polyalkylene oxide having an average functionality of 2 is polyoxypropylene glycol.

[0079] Examples of polyoxypropylene glycol include polyoxypropylene glycol consisting of structural units derived from propylene oxide, and ethylene oxide adducts of polyoxypropylene glycol in which ethylene oxide is added to the terminals.

[0080] The prepolymer raw material polyol preferably contains polyoxypropylene glycol consisting of structural units derived from propylene oxide, and an ethylene oxide adduct of polyoxypropylene glycol having ethylene oxide added to its terminal.

[0081] In particular, when the prepolymer raw material polyol contains an ethylene oxide adduct of polyoxypropylene glycol, the adhesive strength can be improved.

[0082] The mixing ratio of the polyalkylene oxide having an average functionality of 2 is, for example, 20 parts by mass or more, preferably 40 parts by mass or more, and for example, 60 parts by mass or less, preferably 50 parts by mass or less, per 100 parts by mass of the macropolyol.

[0083] Examples of polyalkylene oxides having an average functionality of 3 include polyoxyethylene triol, polyoxypropylene triol, polyoxytriethylene triol, and polyoxyethylene-polyoxypropylene triol (random or block copolymer). A preferred example of the polyalkylene oxide having an average functionality of 3 is polyoxypropylene triol.

[0084] The mixing ratio of the polyalkylene oxide having an average functionality of 3 is, for example, 10 parts by mass or more, preferably 15 parts by mass or more, and for example, 40 parts by mass or less, preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, relative to 100 parts by mass of the macropolyol.

[0085] Examples of polytetramethylene ether polyols include ring-opening polymers (crystalline polytetramethylene ether glycols) obtained by cationic polymerization of tetrahydrofuran, and amorphous (non-crystalline) polytetramethylene ether glycols obtained by copolymerizing alkyl-substituted tetrahydrofuran and the above-mentioned dihydric alcohols with polymerization units of tetrahydrofuran, etc. The term "amorphous (non-crystalline)" refers to a liquid state at room temperature (25°C).

[0086] The mixing ratio of the polytetramethylene ether polyol relative to 100 parts by mass of the macropolyol is, for example, 20 parts by mass or more, preferably 30 parts by mass or more, and for example, 50 parts by mass or less, preferably 40 parts by mass or less.

[0087] The polyether polyol can be used alone or in combination of two or more kinds. Preferably, as the polyether polyol, polyoxypropylene glycol, an ethylene oxide adduct of polyoxypropylene glycol, or polyoxypropylene triol, which are composed of structural units derived from propylene oxide, are used in combination with polytetramethylene ether polyol, or polyoxypropylene glycol, an ethylene oxide adduct of polyoxypropylene glycol, or polyoxypropylene triol, which are composed of structural units derived from propylene oxide, are used in combination. More preferably, polyoxypropylene glycol, an ethylene oxide adduct of polyoxypropylene glycol, or polyoxypropylene triol, which are composed of structural units derived from propylene oxide, are used in combination with polytetramethylene ether polyol.

[0088] The blending ratio of the macropolyol relative to the prepolymer raw material polyol is, for example, 80 mass % or more, preferably 90 mass % or more, more preferably 95 mass % or more, and for example, 100 mass % or less.

[0089] The prepolymer feed polyol optionally contains a low molecular weight polyol.

[0090] The low molecular weight polyol is a compound having two or more hydroxyl groups and a number average molecular weight of less than 300, preferably less than 400.

[0091] Examples of the low molecular weight polyol include the dihydric alcohols exemplified as the raw material polyol for the adduct, and the trihydric alcohols exemplified as the raw material polyol for the adduct.

[0092] The low molecular weight polyols can be used alone or in combination of two or more kinds.

[0093] The mixing ratio of the low molecular weight polyol relative to the prepolymer raw material polyol is, for example, 20 mass % or less, preferably 10 mass % or less, more preferably 5 mass % or less, and for example, 0 mass % or more.

[0094] The prepolymer feed polyol preferably does not include low molecular weight polyols and consists of macro polyols.

[0095] The isocyanate group-terminated prepolymer can be obtained by subjecting a prepolymer raw material polyisocyanate and a prepolymer raw material polyol to a urethane reaction such that the equivalent ratio (NCO / OH) of the isocyanate groups of the prepolymer raw material polyisocyanate to the hydroxyl groups of the prepolymer raw material polyol is greater than 1, preferably 1.3 or more, preferably 1.8 or more, more preferably 2.5 or more, and for example, 50 or less, preferably 3 or less.

[0096] The urethane reaction can be carried out in accordance with a known method.

[0097] In the above reaction, the reaction temperature is, for example, 50° C. or more, and, for example, 120° C. or less, preferably 100° C. or less. The reaction time is, for example, 0.5 hours or more, preferably 1 hour or more, and, for example, 24 hours or less, preferably 15 hours or less.

[0098] The reaction is carried out in the absence of a solvent, which can prevent organic solvent from remaining in the isocyanate composition produced by the method for producing an isocyanate composition. As a result, the decrease in adhesive strength caused by the remaining organic solvent can be prevented.

[0099] In the above reaction, a known urethane catalyst can be added in an appropriate ratio.

[0100] If necessary, unreacted prepolymer raw material polyisocyanate can be removed from the resulting isocyanate-terminated prepolymer by, for example, a known removal means (for example, distillation, extraction).

[0101] The isocyanate group concentration of the isocyanate group-terminated prepolymer is, for example, 3.0 mass% or more, preferably 5.0 mass% or more, more preferably 8.0 mass% or more, even more preferably 10.0 mass% or more, and for example, 20.0 mass% or less, preferably 15 mass% or less.

[0102] The isocyanate group-terminated prepolymer has an amine equivalent of, for example, 200 or more, preferably 300 or more, more preferably 400 or more, and for example, 600 or less, preferably 500 or less.

[0103] As such an isocyanate-terminated prepolymer, preferably, an isocyanate-terminated prepolymer which is a reaction product of an aromatic polyisocyanate and a polyether polyol is used, and more preferably, an isocyanate-terminated prepolymer which is a reaction product of diphenylmethane diisocyanate and a polyether polyol is used.

[0104] (Mixture of polyisocyanate alcohol adduct and isocyanate-terminated prepolymer) In the third step, the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer are mixed at a predetermined temperature (specifically, 80°C or higher and 170°C or lower, preferably 160°C or lower, preferably 120°C or lower, and particularly preferably 100°C or lower).

[0105] By mixing the alcohol adduct of polyisocyanate and the isocyanate group-terminated prepolymer at a predetermined temperature, for example, the viscosity can be reduced without diluting the alcohol adduct of polyisocyanate with an organic solvent, and thus handling properties can be improved. Furthermore, since no organic solvent is used, the organic solvent can be prevented from remaining in the isocyanate composition produced by this method for producing an isocyanate composition. As a result, a decrease in adhesive strength caused by the remaining organic solvent can be prevented.

[0106] Furthermore, the method for mixing the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer at a predetermined temperature is not particularly limited.

[0107] For example, in the second step, when the unreacted adduct raw material polyisocyanate is separated by distillation at a distillation temperature of 80° C. to 170° C., the alcohol adduct of the polyisocyanate heated by distillation is mixed with the isocyanate group-terminated prepolymer. In this method, the third step is carried out at 80° C. to 170° C. by utilizing the distillation temperature in the distillation (preferably without heating in the third step).

[0108] That is, the polyisocyanate alcohol adduct, which has been brought to a predetermined temperature by distillation, is mixed as is with the isocyanate-terminated prepolymer. The temperature may drop slightly during the process from distillation to mixing, but it is sufficient as long as the temperature during mixing (third step) is the above-mentioned predetermined temperature. This method has excellent productivity.

[0109] Alternatively, the alcohol adduct of polyisocyanate obtained in the second step may be distilled and then allowed to cool, and then in the third step, the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer may be mixed while being heated to the above-mentioned predetermined temperature.

[0110] From the viewpoint of productivity, it is preferable to mix the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer that have been heated by distillation.

[0111] In addition, the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer can be mixed all at once or in portions. Preferably, the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer are mixed in portions. When the alcohol adduct of polyisocyanate and the isocyanate-terminated prepolymer are mixed in portions, for example, first, a part of the isocyanate-terminated prepolymer (for example, for example, 20% or more, preferably 40% or more, and for example, 80% or less, preferably 60% or less, based on the entire isocyanate-terminated prepolymer) is mixed with the alcohol adduct of polyisocyanate, and then the remainder of the isocyanate-terminated prepolymer is blended. In addition, in mixing the remainder of the isocyanate-terminated prepolymer and the alcohol adduct of polyisocyanate, the temperature during mixing is not limited to the above-mentioned predetermined temperature. That is, the mixing of the polyisocyanate-alcohol adduct and the isocyanate-terminated prepolymer is sufficient if at least a portion of the isocyanate-terminated prepolymer is mixed with the polyisocyanate-alcohol adduct at the above-mentioned predetermined temperature.

[0112] In the third step, other polyisocyanates can be blended together with the alcohol adduct of the polyisocyanate and the isocyanate-terminated prepolymer. In such a case, the isocyanate composition contains other polyisocyanates.

[0113] Examples of the other polyisocyanates include the polyisocyanates listed in the adduct raw material polyisocyanate. Examples of the other polyisocyanates include preferably liquid diphenylmethane diisocyanate and carbodiimide-modified polymethylene polyphenyl polyisocyanate. Examples of the other polyisocyanates include more preferably liquid diphenylmethane diisocyanate from the viewpoint of improving adhesive strength. That is, the other polyisocyanates more preferably include liquid diphenylmethane diisocyanate.

[0114] Liquid diphenylmethane diisocyanate is obtained by modifying a portion of diphenylmethane diisocyanate with carbodiimide, and is diphenylmethane diisocyanate that is liquid at room temperature (25° C.).

[0115] In the third step, the mixing ratio of the alcohol adduct of polyisocyanate is, per 100 parts by mass of the total amount of the isocyanate group-terminated prepolymer, the alcohol adduct of polyisocyanate, and other polyisocyanates that are mixed as necessary, for example, 1 part by mass or more, preferably 5 parts by mass or more, and for example, 25 parts by mass or less, preferably 15 parts by mass or more.

[0116] In the third step, the mixing ratio of the isocyanate group-terminated prepolymer is, relative to 100 parts by mass of the total amount of the isocyanate group-terminated prepolymer, the alcohol adduct of the polyisocyanate, and other polyisocyanates that are mixed as necessary, is, for example, 60 parts by mass or more, preferably 70 parts by mass or more, and for example, 95 parts by mass or less, preferably 80 parts by mass or less.

[0117] In the third step, the mixing ratio of the other polyisocyanate per 100 parts by mass of the total amount of the isocyanate group-terminated prepolymer, the alcohol adduct of the polyisocyanate, and the other polyisocyanate mixed as necessary is, for example, 0 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and for example, 30 parts by mass or less, preferably 20 parts by mass or less.

[0118] In this manner, an isocyanate composition is produced which contains the isocyanate-terminated prepolymer, the alcohol adduct of the polyisocyanate, and other polyisocyanates which are blended as required.

[0119] The viscosity (50° C.) of the isocyanate composition is, from the viewpoint of handleability, for example, 100 mPa·s or more, preferably 300 mPa·s or more, and for example, 10,000 mPa·s or less, preferably 1,000 mPa·s or less.

[0120] The isocyanate group concentration of the isocyanate composition is, for example, 5 mass% or more, preferably 10 mass% or more, and for example, 30 mass% or less, preferably 25 mass% or less, more preferably 20 mass% or less, and still more preferably 15 mass% or less.

[0121] In addition, since the isocyanate composition is produced without diluting the alcohol adduct of the polyisocyanate with an organic solvent, the isocyanate composition does not substantially contain an organic solvent (e.g., ethyl acetate). The isocyanate composition does not substantially contain an organic solvent means that the concentration of the organic solvent is, for example, less than 100 ppm.

[0122] If the isocyanate composition is substantially free of organic solvents, the adhesive strength is improved.

[0123] The concentration of the organic solvent can be measured by gas chromatography.

[0124] In addition, the first step, the second step, and the third step are carried out in the absence of a solvent. This makes it possible to prevent organic solvent from remaining in the isocyanate composition produced by the method for producing an isocyanate composition herein. As a result, it is possible to prevent a decrease in adhesive strength caused by the remaining organic solvent.

[0125] 2. Second Invention The second invention includes a fourth step of reacting an adduct raw material polyisocyanate and an adduct raw material polyol so that the equivalent ratio (isocyanate groups / hydroxyl groups) of the isocyanate groups in the adduct raw material polyisocyanate to the hydroxyl groups in the adduct raw material polyol is 4.0 or more and 7.0 or less to obtain a reaction liquid containing an alcohol adduct of polyisocyanate; a fifth step of separating unreacted adduct raw material polyisocyanate from the reaction liquid to obtain an alcohol adduct of polyisocyanate; a sixth step of mixing the alcohol adduct of polyisocyanate and additives at 80°C or more and 170°C or less to obtain a mixed liquid; and a seventh step of mixing the mixed liquid and the isocyanate group-terminated prepolymer.

[0126] <4th process> In the fourth step, the adduct raw material polyisocyanate and the adduct raw material polyol are reacted in a predetermined ratio to obtain a reaction liquid containing an alcohol adduct of the polyisocyanate.

[0127] The fourth step is the same as the first step. That is, the adduct raw material polyisocyanate, the adduct raw material polyol, and the reaction conditions in the fourth step are the same as the adduct raw material polyisocyanate, the adduct raw material polyol, and the reaction conditions in the first step.

[0128] This produces a reaction liquid containing an alcohol adduct of polyisocyanate, more specifically, a reaction liquid containing an alcohol adduct of polyisocyanate and unreacted raw material polyisocyanate for the adduct.

[0129] <5th process> In the fifth step, the unreacted polyisocyanate as a raw material for the adduct is separated from the reaction liquid obtained in the fourth step to obtain an alcohol adduct of the polyisocyanate.

[0130] The fifth step is the same as the second step. That is, the separation method in the fifth step is the same as the separation method in the second step.

[0131] <6th process> In the sixth step, the polyisocyanate alcohol adduct and additives are mixed at a predetermined temperature.

[0132] From the viewpoint of handling properties, a preferable example of the additive is a plasticizer.

[0133] The plasticizer preferably has a solubility parameter (SP value) calculated by the Fedors equation of 7.5 (cal / cm 3 ) 1 / 2 More than 13.0(cal / cm 3 ) 1 / 2 The compound is as follows:

[0134] The Fedors formula is a formula for calculating the SP value from cohesive energy density, molar volume (molar molecular volume), etc., and is described in "A Method for Estimating Both the Solubility Parameters and Molar Volumes of Liquids" by RF Fedors (POLYMER ENGINEERING AND SCIENCE, published in February 1974, Vol. 14, No. 2, pp. 147-152). In other words, the SP value calculated by the Fedors formula is a calculated value determined by the molecular structure of the compound.

[0135] Specifically, the plasticizer may be, for example, a carboxylate plasticizer, such as a phthalate ester, an adipic acid ester, a benzoic acid ester, or a hydrogenated phthalate ester.

[0136] As an example of a phthalate ester, there is dimethyl phthalate (SP value: 11.54 (cal / cm 3 ) 1 / 2 ), diethyl phthalate (SP value: 11.07 (cal / cm 3 ) 1 / 2 ), dibutyl phthalate (SP value: 10.47 (cal / cm 3 ) 1 / 2 ), diheptyl phthalate (SP value: 9.96 (cal / cm 3 )1 / 2 ), di-n-octyl phthalate (SP value: 9.85 (cal / cm 3 ) 1 / 2 ), diisooctyl phthalate (SP value: 9.73 (cal / cm 3 ) 1 / 2 ), diethylhexyl phthalate (SP value: 9.73 (cal / cm 3 ) 1 / 2 ), dinonyl phthalate (SP value: 9.30 (cal / cm 3 ) 1 / 2 ), diisononyl phthalate (SP value: 9.64 (cal / cm 3 ) 1 / 2 ), diisodecyl phthalate (SP value: 9.57 (cal / cm 3 ) 1 / 2 ), ditridecyl phthalate (SP value: 9.48 (cal / cm 3 ) 1 / 2 ), and dibutyl pentyl phthalate (SP value: 9.64 (cal / cm 3 ) 1 / 2 ) are mentioned.

[0137] Examples of adipate esters include diisononyl adipate (SP value: 9.13 (cal / cm 3 ) 1 / 2 ), dioctyl adipate (SP value: 9.18 (cal / cm 3 ) 1 / 2 ), and diisodecyl adipate (SP value: 9.09 (cal / cm 3 ) 1 / 2 ) are mentioned.

[0138] Benzoic acid esters include, for example, glycol benzoate (SP value: 10.86 (cal / cm 3 ) 1 / 2 ), diethylene glycol dibenzoate (SP value: 11.30 (cal / cm 3 ) 1 / 2 ), and cyclohexane-1,4-diyldimethylene dibenzoate (SP value: 10.99 (cal / cm 3 ) 1 / 2 ) are mentioned.

[0139] As the hydrogenated phthalate ester, for example, hydrogenated diisononyl phthalate (SP value: 9.22 (cal / cm 3 ) 1 / 2 ) are mentioned.

[0140] As the plasticizer, preferably, a phthalate ester is used, and more preferably, diisodecyl phthalate is used.

[0141] The plasticizers can be used alone or in combination of two or more kinds.

[0142] In the sixth step, the polyisocyanate alcohol adduct and the additives are mixed at a predetermined temperature (specifically, 80°C or higher and 170°C or lower, preferably 160°C or lower, more preferably 120°C or lower, and even more preferably 100°C or lower).

[0143] By mixing the polyisocyanate alcohol adduct and the additive at a predetermined temperature, for example, the viscosity of the polyisocyanate alcohol adduct can be reduced without diluting it with an organic solvent, and thus the handling properties can be improved. Furthermore, since no organic solvent is used, the organic solvent can be prevented from remaining in the isocyanate composition produced by this method for producing an isocyanate composition. As a result, the decrease in adhesive strength caused by the remaining organic solvent can be prevented.

[0144] Furthermore, the method for mixing the alcohol adduct of polyisocyanate and the additives at a predetermined temperature is not particularly limited.

[0145] For example, in the fifth step, when the unreacted raw material polyisocyanate for the adduct is separated by distillation at a distillation temperature of 80° C. to 170° C., the alcohol adduct of the polyisocyanate heated by distillation is mixed with the additive. In this method, the sixth step is carried out at 80° C. to 170° C. by utilizing the distillation temperature in the distillation (preferably, without heating in the sixth step).

[0146] That is, the polyisocyanate alcohol adduct, which has been distilled to a predetermined temperature, is mixed with the additive as is. The temperature may drop slightly during the process from distillation to mixing, but it is sufficient as long as the temperature during mixing (the fifth step) is the above-mentioned predetermined temperature. This method has excellent productivity.

[0147] Alternatively, the polyisocyanate alcohol adduct obtained in the fifth step may be distilled, allowed to cool, and then in the sixth step, the polyisocyanate alcohol adduct and additives may be mixed while being heated to the above-mentioned predetermined temperature.

[0148] From the viewpoint of productivity, it is preferable to mix the alcohol adduct of polyisocyanate heated by distillation with the additives.

[0149] The polyisocyanate alcohol adduct and the plasticizer can be mixed all at once or in portions. Preferably, the polyisocyanate alcohol adduct and the plasticizer are mixed in portions. When the polyisocyanate alcohol adduct and the plasticizer are mixed in portions, for example, first, a part of the plasticizer (for example, 20% or more, preferably 40% or more, and for example, 80% or less, preferably 60% or less, based on the total amount of the plasticizer) is mixed with the polyisocyanate alcohol adduct, and then the remainder of the plasticizer is added. In addition, when the remainder of the plasticizer is mixed with the polyisocyanate alcohol adduct, the temperature during mixing is not limited to the above-mentioned predetermined temperature. That is, the polyisocyanate alcohol adduct and the plasticizer are mixed such that at least a part of the plasticizer is mixed with the polyisocyanate alcohol adduct at the above-mentioned predetermined temperature.

[0150] The mixing ratio of the plasticizer relative to 100 parts by mass of the alcohol adduct of polyisocyanate is, for example, 2 parts by mass or more, preferably 5 parts by mass or more, and for example, 20 parts by mass or less, preferably 15 parts by mass or less.

[0151] This gives a mixed liquid containing the polyisocyanate alcohol adduct and the additives.

[0152] <7th process> In the seventh step, the mixed liquid and the isocyanate-terminated prepolymer are mixed.

[0153] At this time, other polyisocyanates (polyisocyanates similar to the other polyisocyanates listed in the third step) can also be blended.

[0154] In the seventh step, the mixing ratio of the alcohol adduct of polyisocyanate is, for example, 1 part by mass or more, preferably 5 parts by mass or more, and for example, 20 parts by mass or less, preferably 15 parts by mass or more, per 100 parts by mass of the total amount of the isocyanate group-terminated prepolymer, the alcohol adduct of polyisocyanate, and other polyisocyanates that are mixed as necessary.

[0155] In the seventh step, the mixing ratio of the isocyanate-terminated prepolymer is, relative to 100 parts by mass of the total amount of the isocyanate-terminated prepolymer, the alcohol adduct of the polyisocyanate, and other polyisocyanates mixed as necessary, is, for example, 60 parts by mass or more, preferably 70 parts by mass or more, and for example, 95 parts by mass or less, preferably 80 parts by mass or less.

[0156] In the seventh step, the mixing ratio of the other polyisocyanate per 100 parts by mass of the total amount of the isocyanate group-terminated prepolymer, the alcohol adduct of the polyisocyanate, and the other polyisocyanate mixed as necessary is, for example, 0 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and for example, 30 parts by mass or less, preferably 20 parts by mass or less.

[0157] In this manner, an isocyanate composition is produced that contains the isocyanate-terminated prepolymer, the alcohol adduct of the polyisocyanate, additives, and other polyisocyanates that are blended as required.

[0158] The isocyanate composition produced by the second invention, like the isocyanate composition produced by the first invention, is substantially free of organic solvents.

[0159] In addition, the fourth, fifth, sixth and seventh steps are carried out in the absence of a solvent. This makes it possible to prevent organic solvents from remaining in the isocyanate composition produced by the method for producing an isocyanate composition. As a result, it is possible to prevent a decrease in adhesive strength caused by the remaining organic solvent.

[0160] 3. Structural polyurethane adhesive Structural polyurethane adhesives are structural adhesives defined in JIS K 6800 (1985). Specifically, structural polyurethane adhesives are "reliable adhesives that can withstand large loads for long periods of time."

[0161] The structural polyurethane adhesive may be a two-component curing adhesive that includes an isocyanate composition and a polyol composition and that is mixed at the time of use when the isocyanate composition and the polyol composition are separately prepared, or may be a one-component curing adhesive in which the isocyanate composition and the polyol composition are mixed in advance. The structural polyurethane adhesive is preferably a two-component curing adhesive.

[0162] When the structural polyurethane adhesive is a two-component curing adhesive, the isocyanate composition and polyol composition, which are prepared separately, constitute an adhesive kit that is blended (mixed) at the time of use to form a cured product.

[0163] (Polyol Composition) The polyol composition includes a macropolyol.

[0164] Examples of the macropolyol include the macropolyols listed above as the prepolymer raw material polyols.

[0165] As the macropolyols, preferably, polyether polyols, polyester polyols, and polyurethane polyols are included.

[0166] As the polyether polyol, preferably, polyoxyethylene-polyoxypropylene triol (random or block copolymer) is used.

[0167] The polyester polyol is preferably a plant-derived polyester polyol, specifically, a vegetable oil-based polyester polyol obtained by condensation reaction of a hydroxycarboxylic acid such as a hydroxyl group-containing vegetable oil fatty acid (e.g., castor oil fatty acid containing ricinoleic acid, hydrogenated castor oil fatty acid containing 12-hydroxystearic acid, etc.) using the above-mentioned low molecular weight polyol as an initiator under known conditions.

[0168] The polyurethane polyol is a reaction product obtained by reacting a polyisocyanate with the above-mentioned macropolyol in such a ratio that the hydroxyl groups in the macropolyol are in excess relative to the isocyanate groups in the polyisocyanate.

[0169] The polyisocyanate may be any of the polyisocyanates listed above as the adduct raw material polyisocyanate. The polyisocyanate may preferably be an aromatic aliphatic polyisocyanate. The polyisocyanate may more preferably be xylylene diisocyanate (1,3-xylylene diisocyanate).

[0170] As the macropolyol, preferably, a polyether polyol is used.

[0171] That is, a preferable example of the polyurethane polyol is a reaction product of xylylene diisocyanate (1,3-xylylene diisocyanate) and polyether polyol.

[0172] As the macropolyol, preferably, polyester polyol is used.

[0173] The content of the macropolyol in the polyol composition is, for example, 60% by mass or more, preferably 65% ​​by mass or more, and, for example, 95% by mass or less, preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0174] The polyol composition optionally includes a low molecular weight polyol.

[0175] The low molecular weight polyol may be any of the polyols listed as the prepolymer raw material polyols. A preferred low molecular weight polyol is 1,4-butanediol.

[0176] The content ratio of the low molecular weight polyol relative to the polyol composition is, for example, 5 mass% or more, preferably 10 mass% or more, more preferably 20 mass% or more, even more preferably 25 mass% or more, and for example, 40 mass% or less, preferably 35 mass% or less.

[0177] The hydroxyl value of the polyol composition is, for example, 80 mgKOH / g or more, preferably 150 mgKOH / g or more, more preferably 250 mgKOH / g or more, even more preferably 350 mgKOH / g or more, particularly preferably 400 mgKOH / g or more, and for example, 700 mgKOH / g or less, preferably 420 mgKOH / g or less.

[0178] The hydroxyl value can be determined, for example, by JIS K 0070-1992 (acetylation method).

[0179] (Mixing of isocyanate composition and polyol composition) In the case of a two-component curing adhesive, an isocyanate composition and a polyol composition prepared separately are mixed at the time of use to produce a structural polyurethane adhesive. That is, in the case of a two-component curing adhesive, a method for producing a structural polyurethane adhesive includes mixing an isocyanate composition produced by the method for producing an isocyanate composition according to the first invention or the method for producing an isocyanate composition according to the second invention with a polyol composition.

[0180] Specifically, the isocyanate composition and the polyol composition are mixed so that the equivalent ratio of the isocyanate groups in the isocyanate composition to the hydroxyl groups in the polyol composition (isocyanate groups / hydroxyl groups) is, for example, 0.5 or more, preferably 0.6 or more, and for example, 1.8 or less, preferably 1.5 or less.

[0181] In addition, in the above mixing, other additives can be added, such as catalysts (e.g., dibutyltin dilaurate, amine catalysts), antiaging agents, antioxidants, ultraviolet absorbers, heat stabilizers, polymeric light stabilizers, pigments, dyes, defoamers, dispersants, leveling agents, thixotropic agents, antiblocking agents, release agents, lubricants, interlayer adjusters (e.g., glass beads), fillers, and viscosity adjusters.

[0182] This produces a structural polyurethane adhesive containing the isocyanate composition, the polyol composition, and additives which are added as required.

[0183] When such a structural polyurethane adhesive is cured based on the conditions described below (curing temperature, curing time, aging temperature and aging time), the isocyanate composition and the polyol composition react to form a cured product (polyurethane cured product).

[0184] From the viewpoint of handleability, the viscosity (50° C.) of the structural polyurethane adhesive is, for example, 100 mPa·s or more, preferably 300 mPa·s or more, and for example, 10,000 mPa·s or less, preferably 1,000 mPa·s or less.

[0185] In addition, since the structural polyurethane adhesive uses an isocyanate composition produced in the above-mentioned method for producing an isocyanate composition without diluting the alcohol adduct of a polyisocyanate with an organic solvent, the structural polyurethane adhesive is substantially free of organic solvents. The structural polyurethane adhesive being substantially free of organic solvents means that the concentration of the organic solvent is, for example, less than 100 ppm.

[0186] The concentration of the organic solvent can be measured by gas chromatography.

[0187] Adhesive strength is improved if the structural polyurethane adhesive is substantially free of organic solvents.

[0188] Structural polyurethane adhesives have excellent adhesive strength and are therefore suitable for use in structures made up of a plurality of components for bonding the components together, such as components for buildings, automobiles, transport equipment, and ships.

[0189] To bond the various components together, the various components are bonded together using a structural polyurethane adhesive, and then the adhesive is heated, if necessary, and aged, if necessary, to harden the structural polyurethane adhesive.

[0190] Curing conditions for the structural polyurethane adhesive include a curing temperature of, for example, 10° C. or more, preferably 16° C. or more, for example, 80° C. or less, preferably 60° C. or less, more preferably 30° C. or less, and a curing time of, for example, 5 minutes or more, preferably 10 minutes or more, for example, 600 minutes or less, preferably 120 minutes or less, more preferably 60 minutes or less.

[0191] As for the aging conditions, the aging temperature is, for example, 20° C. or more, preferably 25° C. or more, and for example, 80° C. or less, preferably 60° C. or less, more preferably 40° C. or less. The aging time is, for example, 1 day or more, preferably 3 days or more, more preferably 7 days or more, and for example, 14 days or less, preferably 10 days or less.

[0192] 4. Effects The method for producing an isocyanate composition includes a third step of mixing an alcohol adduct of polyisocyanate and an isocyanate-terminated prepolymer at 80° C. or higher and 170° C. or a sixth step of mixing an alcohol adduct of polyisocyanate and an additive at 80° C. or higher and 170° C. or lower to obtain a mixed liquid. Therefore, an isocyanate composition for producing a structural polyurethane adhesive with excellent adhesive strength can be produced.

[0193] More specifically, in the above-mentioned Prior Art Document 1, in the method for producing an isocyanate composition, an alcohol adduct of a polyisocyanate is diluted with an organic solvent from the viewpoint of improving handleability.

[0194] On the other hand, the organic solvent is removed by a known method, but even if the solvent is removed, it is not possible to remove all of the organic solvent from the isocyanate composition, and the organic solvent may remain in the isocyanate composition. In this case, there is a problem that the adhesive strength is reduced due to the remaining organic solvent.

[0195] In contrast, the method for producing the isocyanate composition includes a third step of mixing an alcohol adduct of polyisocyanate and an isocyanate-terminated prepolymer at 80°C or higher and 170°C or lower, or a sixth step of mixing an alcohol adduct of polyisocyanate and additives at 80°C or higher and 170°C or lower to obtain a mixed liquid.

[0196] Therefore, the handleability can be improved without diluting the alcohol adduct of the polyisocyanate with an organic solvent. In addition, since the alcohol adduct of the polyisocyanate is not diluted with an organic solvent, the organic solvent can be prevented from remaining in the isocyanate composition. As a result, the decrease in adhesive strength caused by the remaining organic solvent can be prevented, and the adhesive strength can be improved.

[0197] The method for producing a structural polyurethane adhesive uses an isocyanate composition produced by the above-mentioned method for producing an isocyanate composition, and therefore a structural polyurethane adhesive having excellent adhesive strength can be produced.

[0198] In addition, such structural polyurethane adhesives contain substantially no organic solvents, and therefore have excellent adhesive strength.

[0199] 5. Variations In the first invention described above, the other polyisocyanate is blended in the third step, but the other polyisocyanate can also be blended after the third step.

[0200] In the second invention described above, the other polyisocyanate is blended in the seventh step, but the other polyisocyanate can also be blended after the sixth step or the seventh step.

[0201] In the above description, other additives are added when the isocyanate composition and the polyol composition are mixed, but other additives may also be added in advance to the isocyanate composition and / or the polyol composition. EXAMPLES

[0202] 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".

[0203] <Ingredients> Details of the abbreviations used in each Production Example, each Example and each Comparative Example are described below. Actocol D-400: Polyoxypropylene glycol, number average molecular weight 400, manufactured by Mitsui Chemicals Mitsui Chemicals Actocol EP-330N: Polyoxyethylene-polyoxypropylene glycol (block copolymer), hydroxyl value 33 mgKOH / g, manufactured by Mitsui Chemicals Actocol EP-550N: Polyoxyethylene-polyoxypropylene glycol (block copolymer), hydroxyl value 54 mgKOH / g, manufactured by Mitsui Chemicals Hydroxyl-terminated urethane prepolymer: A polyurethane polyol (hydroxyl group / isocyanate group=3.0) obtained by reacting 1,3-xylylene diisocyanate (XDI) with Actocol T-700 (product name, polyether polyol with number average molecular weight of 700 and average number of hydroxyl groups of 3, manufactured by Mitsui Chemicals) at 80°C for 1 hour and then at 90°C for 4 hours. ECONICOL EBT-509: Castor oil-derived polyester polyol, hydroxyl value 63mgKOH / g, manufactured by Mitsui Chemicals Coronate MX: Liquid diphenylmethane diisocyanate, manufactured by Tosoh Corporation Cosmonate LL: Carbodiimide-modified polymethylene polyphenyl polyisocyanate, manufactured by Mitsui Chemicals Dabco 33LV, amine catalyst, manufactured by Evonik DBTDL: dibutyltin dilaurate, manufactured by Tokyo Chemical Industry Co., Ltd. DIDP: Diisodecyl phthalate, manufactured by JPlus

[0204] <Production of isocyanate-terminated prepolymer> Production Example 1-A (MDI prepolymer) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, the following polymer raw material polyisocyanate, the following prepolymer raw material polyol, and 0.1 parts by mass of o-toluenesulfonamide (OTSA: stabilizer) were blended. The equivalent ratio (NCO / OH) of the isocyanate group of the prepolymer raw material polyisocyanate to the hydroxyl group of the prepolymer raw material polyol was set to 2.8. Next, the mixture was stirred in a nitrogen stream at 60°C for 1 hour, and further stirred at 80°C for 4 to 12 hours to cause a urethane reaction. In this way, an isocyanate group-terminated prepolymer (MDI prepolymer) was produced. The solid content concentration of the isocyanate group-terminated prepolymer was 100% by mass, the amine equivalent was 489, and the isocyanate group content was 8.6% by mass. Prepolymer raw material polyisocyanate: 4,4'-diphenylmethane diisocyanate (MDI) 397.8 parts by mass Prepolymer raw material polyol: Actocol D-1000 (polyoxypropylene glycol, number average molecular weight 1000, manufactured by Mitsui Chemicals) 137.7 parts by mass, Takelac P-24 (ethylene oxide adduct of polyoxypropylene glycol, number average molecular weight about 2000, manufactured by Mitsui Chemicals) 149.9 parts by mass, Actocol T-1000D (polyoxypropylene triol, number average molecular weight 1000, manufactured by Mitsui Chemicals) 107.5 parts by mass, and PTG-1000 (polytetramethylene ether glycol, number average molecular weight 1000, manufactured by Hodogaya Chemical Co., Ltd.) 207.0 parts by mass

[0205] Production Example 1-B (MDI prepolymer) An isocyanate-terminated prepolymer (MDI prepolymer) was produced in the same manner as in Production Example 1-A. However, the polymer raw material polyisocyanate and prepolymer raw material polyol were changed as follows. The solid content of the isocyanate-terminated prepolymer was 100% by mass, the amine equivalent was 489, and the isocyanate group content was 8.6% by mass. Prepolymer raw material polyisocyanate: 4,4'-diphenylmethane diisocyanate (MDI) 417.8 parts by mass Prepolymer raw material polyol: Actocol D-1000 (polyoxypropylene glycol, number average molecular weight 1000, manufactured by Mitsui Chemicals, Inc.) 366.4 parts by mass, Takelac P-24 (ethylene oxide adduct of polyoxypropylene glycol, number average molecular weight about 2000, manufactured by Mitsui Chemicals, Inc.) 154.4 parts by mass, Actocol T-1000D (polyoxypropylene triol, number average molecular weight 1000, manufactured by Mitsui Chemicals, Inc.) 110.7 parts by mass

[0206] <Production of polyisocyanate derivatives> In the following description, the preparation of a polyisocyanate derivative to be used in place of an alcohol adduct of polyisocyanate will be described in detail in a comparative example.

[0207] Production Example 2-A (Polyisocyanate (HDI / Actocol D-400)) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 281.3 parts by mass of Actocol D-400 (polyoxypropylene glycol, number average molecular weight 400, manufactured by Mitsui Chemicals), 718.5 parts by mass of hexamethylene diisocyanate (HDI, manufactured by Tosoh Corporation), and 0.2 parts by mass of OTSA were blended. The equivalent ratio (NCO / OH) of the isocyanate group of hexamethylene diisocyanate to the hydroxyl group of Actocol D-400 was set to 6. Next, the mixture was stirred in a nitrogen stream at 110°C for 6 to 24 hours to cause a urethane reaction. This produced a reaction liquid containing polyisocyanate (HDI / Actocol D-400). The isocyanate group content of the polyisocyanate (HDI / Actocol D-400) was 30.0% by mass.

[0208] Production Example 2-B (PDI Isocyanurate) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of 1,5-pentamethylene diisocyanate (PDI, trade name STABIO PDI, manufactured by Mitsui Chemicals, Inc.), 0.25 parts by mass of 2,6-di(tert-butyl)-4-methylphenol (hindered phenol-based antioxidant), and 0.25 parts by mass of tetraphenyl dipropylene glycol diphosphite (organic phosphorous ester, cocatalyst) were mixed under a nitrogen atmosphere to obtain a mixed liquid. Then, 6.5 parts by mass of isobutanol was added to this mixed liquid, and nitrogen was introduced for 1 hour.

[0209] After that, the mixture was heated to 80°C and reacted for 3 hours, then cooled to 60°C. Next, 0.2 parts by mass of trimethyl-N-2-hydroxypropylammonium 2-ethylhexanoate was added as an isocyanurate catalyst and reacted for 1.5 hours. After that, 0.01 parts by mass of o-toluenesulfonamide was added per 100 parts by mass of PDI. This produced a reaction liquid containing polyisocyanate (PDI isocyanurate). The isocyanate group content of the polyisocyanate (PDI isocyanurate) was 23.2% by mass.

[0210] Production Example 2-C (HDI Isocyanurate) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of 1,6-hexamethylene diisocyanate (HDI, manufactured by Tosoh Corporation), 0.25 parts by mass of 2,6-di(tert-butyl)-4-methylphenol (another hindered phenol-based antioxidant), and 0.25 parts by mass of tetraphenyl dipropylene glycol diphosphite (organic phosphorous ester, cocatalyst) were mixed under a nitrogen atmosphere to obtain a mixed solution. Then, 10.7 parts by mass of 1,3-butanediol was added to this mixed solution, and nitrogen was introduced for 1 hour.

[0211] After that, the mixture was heated to 80°C and reacted for 3 hours, then cooled to 60°C. Next, 0.2 parts by mass of trimethyl-N-2-hydroxypropylammonium 2-ethylhexanoate was added as an isocyanurate catalyst and reacted for 1.5 hours. After that, 0.01 parts by mass of o-toluenesulfonamide was added per 100 parts by mass of HDI. This produced a reaction liquid containing polyisocyanate (HDI isocyanurate). The isocyanate group content of the polyisocyanate (HDI isocyanurate) was 20.9% by mass.

[0212] Manufacturing example 2-D (PDI / TMP R=2) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of 1,5-PDI (trade name: STABIOPDI, manufactured by Mitsui Chemicals, Inc.) was mixed under a nitrogen atmosphere, and then 145 parts by mass of trimethylolpropane (TMP) was mixed. The equivalent ratio (NCO / OH) of the isocyanate group of 1,5-pentamethylene diisocyanate to the hydroxyl group of trimethylolpropane (TMP) was set to 2.0. Then, the mixture was reacted at 80°C for 24 hours. This produced a reaction liquid containing polyisocyanate (PDI / TMP R=2). The polyisocyanate (PDI / TMP R=2) had an isocyanate group content of 21.1% by mass.

[0213] <Production of alcohol adduct of polyisocyanate> Manufacturing example 2-E (PDI / TMP R=5.8) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of 1,5-PDI as an adduct raw material polyisocyanate and 50.0 parts by mass of trimethylolpropane (TMP) as an adduct raw material polyol were mixed. The equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group in the adduct raw material polyisocyanate to the hydroxyl group in the adduct raw material polyol was set to 5.8. Thereafter, the temperature was raised to 75°C under a nitrogen atmosphere, and after confirming that the trimethylolpropane had dissolved, the reaction was continued at 83°C until the isocyanate group concentration reached 41.1% by mass. As a result, a reaction liquid containing an alcohol adduct of polyisocyanate was obtained.

[0214] Manufacturing example 2-F (PDI / (TMP+1,3BG)) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of 1,5-PDI as an adduct raw material polyisocyanate, and a mixture of 43.5 parts by mass of trimethylolpropane and 4.9 parts by mass of 1,3-butanediol (1,3-BG) as an adduct raw material polyol (average functionality: 2.9) were blended. The equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group in the adduct raw material polyisocyanate to the hydroxyl group in the adduct raw material polyol was set to 6.0. Thereafter, the temperature was raised to 75°C under a nitrogen atmosphere, and after confirming that the trimethylolpropane had dissolved, the reaction was continued at 83°C until the isocyanate group concentration reached 41.5% by mass. As a result, a reaction liquid containing an alcohol adduct of polyisocyanate was obtained.

[0215] Manufacturing example 2-G (HDI / TMP) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of HDI as the adduct raw material polyisocyanate and 45.8 parts by mass of trimethylolpropane as the adduct raw material polyol were mixed. The equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group in the adduct raw material polyisocyanate to the hydroxyl group in the adduct raw material polyol was set to 5.8. Thereafter, the temperature was raised to 75°C under a nitrogen atmosphere, and after confirming that the trimethylolpropane had dissolved, the reaction was continued at 83°C until the isocyanate group concentration reached 37.9% by mass. As a result, a reaction liquid containing an alcohol adduct of polyisocyanate was obtained.

[0216] Manufacturing example 2-H (XDI / TMP) In a four-neck flask equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 500 parts by mass of xylylene diisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate 500, XDI) as an adduct raw material polyisocyanate and 35.5 parts by mass of trimethylolpropane were mixed. The equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group in the adduct raw material polyisocyanate to the hydroxyl group in the adduct raw material polyol was set to 6.7. Thereafter, the temperature was raised to 75°C under a nitrogen atmosphere, and after confirming that the trimethylolpropane had dissolved, the reaction was continued at 83°C until the isocyanate group concentration reached 35.5% by mass. As a result, a reaction liquid containing an alcohol adduct of polyisocyanate was obtained.

[0217] <Production of isocyanate composition> Examples 1 to 19 and Comparative Examples 1 to 7 (Method for Producing Isocyanate Composition According to the First Invention) [1st step] According to the above Production Examples 2-E to 2-H, the adduct raw material polyisocyanate and the adduct raw material polyol were reacted in a predetermined ratio to produce a reaction liquid containing an alcohol adduct of polyisocyanate. In Comparative Examples 2 to 6, polyisocyanate derivatives were produced according to the above Production Examples 2-A to 2-D.

[0218] [Second and third steps] In the second step, the unreacted raw polyisocyanate adduct was separated from the reaction liquid to obtain an alcohol adduct of polyisocyanate. In the third step, the alcohol adduct of polyisocyanate, the isocyanate-terminated prepolymer and other polyisocyanates were mixed at 90°C.

[0219] Specifically, only a part (half of the blending recipe) of the isocyanate-terminated prepolymer shown in Tables 1 to 3 was blended on the polyisocyanate receiver side of the thin-film distillation apparatus. Next, the reaction liquid containing the alcohol adduct of polyisocyanate was passed through the thin-film distillation apparatus and distilled until the amount of residual isocyanate monomer was 1.0 mass% or less. Then, the alcohol adduct of polyisocyanate heated by distillation was mixed with the isocyanate-terminated prepolymer. Then, the remainder of the isocyanate-terminated prepolymer and other polyisocyanates were blended. In this way, an isocyanate composition was produced. In addition, in the above thin-film distillation, the degree of vacuum was 0.05 kPa and the distillation temperature was 130°C in Examples 1 to 18, Comparative Examples 2 to 5, and Comparative Example 7, and the degree of vacuum was 0.05 kPa and the distillation temperature was 155°C in Example 19.

[0220] The second step was not carried out in Comparative Example 6. Furthermore, in Comparative Example 6, the compatibility between the alcohol adduct of polyisocyanate and the isocyanate group-terminated prepolymer was low.

[0221] In addition, in Comparative Example 7, the third step was not carried out. Specifically, in Comparative Example 7, ethyl acetate was blended into the polyisocyanate receiver side of the thin-film distillation apparatus. Next, the reaction liquid containing the alcohol adduct of polyisocyanate was passed through the thin-film distillation apparatus and distilled until the amount of remaining isocyanate monomer was 1.0 mass% or less (vacuum degree: 0.05 kPa, distillation temperature: 130°C). Then, the alcohol adduct of polyisocyanate heated by distillation was mixed with ethyl acetate to prepare a solution of the alcohol adduct of polyisocyanate (solid content concentration 75 mass%). Thereafter, the solution of the alcohol adduct of polyisocyanate was mixed with the isocyanate group-terminated prepolymer and other polyisocyanates, and then the ethyl acetate was distilled off under reduced pressure conditions.

[0222] Example 20, Example 21 and Comparative Example 8 (Method for Producing Isocyanate Composition According to the Second Invention)

[0223] [4th step] According to the above Production Example 2-E and Production Example 2-G, the adduct raw material polyisocyanate and the adduct raw material polyol were reacted in a predetermined ratio to produce a reaction liquid containing an alcohol adduct of polyisocyanate.

[0224] [Steps 5 and 6] In the fifth step, the unreacted polyisocyanate as the raw material for the adduct was separated from the reaction liquid to obtain an alcohol adduct of the polyisocyanate. In the sixth step, the alcohol adduct of the polyisocyanate and the plasticizer were mixed at 90°C.

[0225] Specifically, only a portion (half of the formulation) of the plasticizer shown in Table 4 was blended into the polyisocyanate receiver side of the thin-film distillation apparatus. Next, the reaction liquid containing the alcohol adduct of polyisocyanate was passed through the thin-film distillation apparatus and distilled until the amount of residual isocyanate monomer was 1.0 mass% or less (degree of vacuum: 0.05 kPa, distillation temperature: 130°C). Then, the alcohol adduct of polyisocyanate heated by the distillation in the fifth step and the plasticizer were mixed. Thereafter, the remainder of the plasticizer was blended, thereby obtaining a mixed liquid containing the alcohol adduct of polyisocyanate and the plasticizer.

[0226] [Step 7] The above mixture, an isocyanate-terminated prepolymer and other polyisocyanates were mixed to produce an isocyanate composition.

[0227] In Comparative Example 8, the sixth step was not carried out. Specifically, in Comparative Example 8, ethyl acetate was blended into the polyisocyanate receiver side of the thin-film distillation apparatus. Next, the reaction liquid containing the alcohol adduct of polyisocyanate was passed through the thin-film distillation apparatus and distilled until the amount of residual isocyanate monomer was 1.0 mass% or less (vacuum degree 0.05: kPa, distillation temperature: 130°C). Then, the alcohol adduct of polyisocyanate heated by distillation was mixed with ethyl acetate to prepare a solution of the alcohol adduct of polyisocyanate (solid content concentration 75 mass%). Thereafter, the solution of the alcohol adduct of polyisocyanate was mixed with a plasticizer, and then the ethyl acetate was distilled off under reduced pressure conditions.

[0228] <Structural polyurethane adhesive> Based on the formulations shown in Tables 1 to 4, the isocyanate composition of each Example or Comparative Example, the polyol composition, and other additives were mixed to produce a structural polyurethane adhesive.

[0229] <Evaluation> [Handling] In each of the Examples and Comparative Examples, the handleability of the polyisocyanate-alcohol adduct and the polyisocyanate that was blended at the same time as the polyisocyanate-alcohol adduct was evaluated.

[0230] Specifically, the viscosity of the polyisocyanate alcohol adduct and the polyisocyanate that was mixed at the same time as the polyisocyanate alcohol adduct were measured. Specifically, the viscosity of the sample was measured at 50°C under temperature control using a Brookfield type rotational viscometer, Type B, described in JIS K 7117-1 (1999). The handleability was evaluated based on the following criteria. The results are shown in Tables 1 to 4. {standard} ◯: Viscosity was 10,000 mPa·s or less. ×: Viscosity exceeded 10,000 mPa·s.

[0231] [Organic solvent concentration] The organic solvent concentration (specifically, the ethyl acetate concentration in the isocyanate composition and the ethyl acetate concentration in the structural polyurethane adhesive) of each of the examples and comparative examples was measured by gas chromatography. The results are shown in Tables 1 to 4.

[0232] [Adhesive strength] A polypropylene plate (J707G, manufactured by Prime Polymer (PP)) was cut to a width of 25 mm. The surface of the PP was then degreased and cleaned with isopropyl alcohol, and then dried. This was then corona treated to adjust the wettability (JIS K 6768 (1999)) to 40 dyn / cm or more. This resulted in a first adherend.

[0233] Separately, a cold-rolled steel plate (SPCC) was cut to a width of 25 mm and cathodic electrocoating (ED) was applied to prepare an ED-SPCC plate (JIS G 3141 (SPCC, SD), Test Piece). Next, the surface of the ED-SPCC was degreased and washed with isopropyl alcohol, and then dried. This resulted in a second adherend.

[0234] Next, the structural polyurethane adhesive of each Example and Comparative Example was applied to the first adherend, and the first adherend and the second adherend were attached to each other so that the adhesive area was 25 mm x 12.5 mm and the adhesive layer thickness was 0.3 mm. The adhesive was cured for 20 minutes at room temperature (19 to 27°C, 40 to 60% RH (relative humidity)) and then aged at room temperature for one week. In addition, glass beads (ASGB-60, AS ONE, 0.250 to 0.355 mm) for layer thickness adjustment were placed in an appropriate amount (about several tens of beads) on the adhesive surface (the surface of the adhesive after the adhesive was applied to the first adherend) for layer thickness adjustment. In this way, an adhesion test specimen was obtained.

[0235] The shear adhesive strength (hereinafter, adhesive strength) [MPa] between the first adherend and the second adherend 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. The adhesive strength was evaluated based on the following criteria. The results are shown in Tables 1 to 4. {standard} ◯: The adhesive strength was 5.5 MPa or more. Δ: The adhesive strength was 5.0 MPa or more and less than 5.5 MPa. ×: The adhesive strength was less than 5.0 MPa.

[0236] <Consideration> Examples 1 to 19 relate to a method for producing an isocyanate composition according to the first invention.

[0237] Examples 1 to 19, in which the third step of mixing the polyisocyanate alcohol adduct and the isocyanate group-terminated prepolymer is carried out at 80°C or higher and 170°C or lower, are excellent in handleability. In addition, since the polyisocyanate alcohol adduct is not diluted with an organic solvent, it is possible to suppress the organic solvent from remaining in the isocyanate composition and the structural polyurethane adhesive. As a result, it is found that the decrease in adhesive strength caused by the remaining organic solvent is suppressed, and the adhesive strength can be improved.

[0238] On the other hand, in Comparative Example 7, the third step was not carried out, and the alcohol adduct of polyisocyanate was diluted with ethyl acetate, and then mixed with the isocyanate-terminated prepolymer, and then the ethyl acetate was distilled off.

[0239] Since the polyisocyanate alcohol adduct is diluted with ethyl acetate, it is easy to handle, but the ethyl acetate could not be completely removed by distillation. As a result, it is understood that the adhesive strength is reduced due to the remaining organic solvent.

[0240] Examples 20 and 21 relate to a method for producing an isocyanate composition according to the second invention.

[0241] Examples 20 and 21, in which the sixth step of mixing the polyisocyanate alcohol adduct and the additive (plasticizer) to obtain a mixed liquid at 80°C or higher and 170°C or lower, are performed, are excellent in handling. In addition, since the polyisocyanate alcohol adduct is not diluted with an organic solvent, it is possible to suppress the organic solvent from remaining in the isocyanate composition and the structural polyurethane adhesive. As a result, it is found that the decrease in adhesive strength caused by the remaining organic solvent is suppressed, and the adhesive strength can be improved.

[0242] On the other hand, in Comparative Example 8, the sixth step was not carried out, and the alcohol adduct of polyisocyanate was diluted with ethyl acetate, mixed with an additive (plasticizer), and then the ethyl acetate was distilled off.

[0243] Since the polyisocyanate alcohol adduct is diluted with ethyl acetate, it is easy to handle, but the ethyl acetate could not be completely removed by distillation. As a result, it is understood that the adhesive strength is reduced due to the remaining organic solvent.

[0244] [Table 1]

[0245] [Table 2]

[0246]

Table 3

[0247]

Table 4

Claims

1. A method for producing an isocyanate composition comprising producing an isocyanate composition containing an isocyanate group-terminated prepolymer and an alcohol adduct of a polyisocyanate, the method comprising the steps of: the isocyanate-terminated prepolymer is a reaction product of a prepolymer raw material polyisocyanate containing an aromatic polyisocyanate and a prepolymer raw material polyol, The alcohol adduct of the polyisocyanate is a reaction product of an adduct raw material polyisocyanate and an adduct raw material polyol containing a trifunctional or higher alcohol, The method for producing the isocyanate composition includes the steps of: a first step of reacting the adduct raw material polyisocyanate and the adduct raw material polyol so that an equivalent ratio (isocyanate group / hydroxyl group) of an isocyanate group in the adduct raw material polyisocyanate to a hydroxyl group in the adduct raw material polyol is 4.0 or more and 7.0 or less to obtain a reaction liquid containing an alcohol adduct of the polyisocyanate; a second step of separating an unreacted adduct raw material polyisocyanate from the reaction liquid to obtain an alcohol adduct of the polyisocyanate; and a third step of mixing the alcohol adduct of the polyisocyanate and the isocyanate group-terminated prepolymer at 80°C or higher and 170°C or lower.

2. A method for producing an isocyanate composition, which produces an isocyanate composition containing an isocyanate group-terminated prepolymer, an alcohol adduct of a polyisocyanate, and an additive, comprising the steps of: the isocyanate-terminated prepolymer is a reaction product of a prepolymer raw material polyisocyanate containing an aromatic polyisocyanate and a prepolymer raw material polyol, The alcohol adduct of the polyisocyanate is a reaction product of an adduct raw material polyisocyanate and an adduct raw material polyol containing a trifunctional or higher alcohol, The method for producing the isocyanate composition includes the steps of: a fourth step of reacting the adduct raw material polyisocyanate and the adduct raw material polyol so that an equivalent ratio (isocyanate group / hydroxyl group) of an isocyanate group in the adduct raw material polyisocyanate to a hydroxyl group in the adduct raw material polyol is 4.0 or more and 7.0 or less to obtain a reaction liquid containing an alcohol adduct of the polyisocyanate; A fifth step of separating an unreacted adduct raw material polyisocyanate from the reaction liquid to obtain an alcohol adduct of the polyisocyanate; A sixth step of mixing the alcohol adduct of the polyisocyanate and the additives at a temperature of 80° C. or higher and 170° C. or lower to obtain a mixed liquid; and a seventh step of mixing the mixed liquid and the isocyanate group-terminated prepolymer.

3. In the second step, separation is performed by distillation at a distillation temperature of 80° C. or more and 170° C. or less, 2. The method for producing an isocyanate composition according to claim 1, wherein in the third step, the alcohol adduct of the polyisocyanate heated by the distillation is mixed with the isocyanate group-terminated prepolymer.

4. In the fifth step, the mixture is separated by distillation at a distillation temperature of 80° C. or more and 170° C. or less, The method for producing an isocyanate composition according to claim 2, wherein in the sixth step, the alcohol adduct of the polyisocyanate heated by the distillation is mixed with an additive to obtain a mixed liquid.

5. The method for producing an isocyanate composition according to claim 2, wherein the additive is a plasticizer.

6. The method for producing an isocyanate composition according to claim 1 or 2, wherein the adduct raw material polyisocyanate is an aliphatic polyisocyanate.

7. The method for producing an isocyanate composition according to claim 1 or 2, wherein the tri- or higher functional alcohol is trimethylolpropane.

8. The isocyanate composition further comprises another polyisocyanate, The method for producing an isocyanate composition according to claim 1 or 2, wherein the other polyisocyanate includes liquid diphenylmethane diisocyanate.

9. 3. The method for producing an isocyanate composition according to claim 1, wherein the prepolymer raw material polyol contains an ethylene oxide adduct of polyoxypropylene glycol.

10. An isocyanate composition produced by the method for producing an isocyanate composition according to claim 1 or 2; A method for producing a structural polyurethane adhesive comprising mixing the polyurethane composition with a polyol composition.

11. An isocyanate composition and a polyol composition, Substantially free of organic solvents; The isocyanate composition includes an isocyanate group-terminated prepolymer and an alcohol adduct of a polyisocyanate, the isocyanate-terminated prepolymer is a reaction product of a prepolymer raw material polyisocyanate containing an aromatic polyisocyanate and a prepolymer raw material polyol, The structural polyurethane adhesive, wherein the alcohol adduct of polyisocyanate is a reaction product of an adduct raw material polyisocyanate and an adduct raw material polyol containing an alcohol having three or more functional groups.

12. An isocyanate composition and a polyol composition, Substantially free of organic solvents; The isocyanate composition includes an isocyanate group-terminated prepolymer, an alcohol adduct of a polyisocyanate, and an additive; the isocyanate-terminated prepolymer is a reaction product of a prepolymer raw material polyisocyanate containing an aromatic polyisocyanate and a prepolymer raw material polyol, The structural polyurethane adhesive, wherein the alcohol adduct of polyisocyanate is a reaction product of an adduct raw material polyisocyanate and an adduct raw material polyol containing an alcohol having three or more functional groups.

Images