Urethane adhesive composition

Abstract

To provide a urethane adhesive composition capable of suppressing deterioration in physical properties of a cured product obtained even if a mixing ratio of a main agent and a curing agent deviates from a designed range.SOLUTION: There is provided a two-pack type urethane adhesive composition comprising a main agent and a curing agent, wherein the main agent includes a polyisocyanate component, the isocyanate group content in the main agent is 5 mass% or more of a total amount of the main agent, the curing agent includes a compound having a plurality of active hydrogen-containing groups in one molecule and the compound having a plurality of active hydrogen-containing groups in the one molecule includes a high molecular weight polyol having 2 to 3 hydroxy groups per molecule and a number average molecular weight of 1800 or more, a low molecular weight polyol A having 2 hydroxy groups per molecule and a number average molecular weight of 200 or less and a low molecular weight polyol B having 3 hydroxy groups per molecule in which at least one or all of the 3 hydroxy groups is a secondary hydroxy group and which has a number average molecular weight of 1200 or less.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Conventionally, a two-component urethane-based composition has been used as an adhesive, and for example, a two-part polyurethane described in Patent Document 1 has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A two-component urethane adhesive composition having a main agent and a curing agent (in a broad sense) is required to have excellent adhesive strength and elastic modulus. In recent years, the required level has been increasing. The high adhesive strength and elastic modulus of the above urethane adhesive composition are achieved by increasing the density of urethane bonds and urea bonds that become hard segments in the cured product. As a method for increasing the density of urethane bonds and the like, for example, the number of isocyanate-reactive groups in the curing agent and the number of isocyanate groups in the main agent in the two-component state are made close to each other, and the number of isocyanate-reactive groups in the curing agent and the number of isocyanate groups in the main agent, or the mixing ratio of the main agent and the curing agent is designed.

[0005] Under such circumstances, when the present inventor prepared a urethane adhesive composition with reference to Patent Document 1 and evaluated it, it was found that the physical properties (for example, breaking strength, elastic modulus) of the cured product obtained when the mixing ratio of the main agent and the curing agent deviated from the designed range were significantly lower than those when the main agent and the curing agent were used at the designed mixing ratio.

[0006] Therefore, an object of the present invention is to provide a urethane adhesive composition capable of suppressing a decrease in the physical properties of a cured product obtained even when the mixing ratio of the main agent and the curing agent deviates from the designed range.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the present inventor has found that in a two-component urethane adhesive composition in which the main agent has a high isocyanate group content, by containing a specific high molecular weight polyol and two low molecular weight polyols in the curing agent, an effect can be obtained that even when the mixing ratio of the main agent and the curing agent deviates from the designed range, a decrease in the physical properties of the cured product obtained can be suppressed, and thus the present invention has been achieved. The present invention is based on the above findings and the like, and specifically solves the above problems by the following configuration.

[0008] [1] A two-component urethane adhesive composition having a main agent and a curing agent, wherein the main agent contains a polyisocyanate component, and the isocyanate group content in the main agent is 5% by mass or more in the total amount of the main agent, the curing agent contains a compound having a plurality of active hydrogen-containing groups in one molecule, the compound having a plurality of active hydrogen-containing groups in one molecule contains a high molecular weight polyol having 2 to 3 hydroxy groups per molecule and a number average molecular weight of 1800 or more, a low molecular weight polyol A having 2 hydroxy groups per molecule and a number average molecular weight of 200 or less, and a low molecular weight polyol B having 3 hydroxy groups per molecule, at least one or all of the 3 hydroxy groups being secondary hydroxy groups and having a number average molecular weight of 1200 or less, the urethane adhesive composition. [2] The low molecular weight polyol B having three hydroxy groups per molecule and a trivalent aliphatic hydrocarbon group having 3 or more carbon atoms, the three hydroxy groups being bonded to the trivalent aliphatic hydrocarbon group, at least one or all of the three hydroxy groups being secondary hydroxy groups, and having a number average molecular weight of 1200 or less, aliphatic hydrocarbon triol B1, and / or having three hydroxy groups per molecule and a trivalent polyoxyalkylene group, the three hydroxy groups each independently forming -R-OH, where each R independently represents a divalent alkylene group, at least one or all of the three hydroxy groups being secondary hydroxy groups, the -R-OH being bonded to the trivalent polyoxyalkylene group, and having a number average molecular weight of 1200 or less, the urethane adhesive composition according to [1], comprising polyoxyalkylene triol B2. [3] The urethane adhesive composition according to [1] or [2], wherein the low molecular weight polyol B contains glycerin. [4] The urethane adhesive composition according to any one of [1] to [3], wherein the low molecular weight polyol A contains an alkanediol. [5] The urethane adhesive composition according to any one of [1] to [4], wherein the low molecular weight polyol A contains 1,4-butanediol. [6] The urethane adhesive composition according to any one of [1] to [5], wherein the polyisocyanate component contains at least one selected from the group consisting of a urethane prepolymer, diphenylmethane diisocyanate, polymeric MDI, and modified MDI. [7] The urethane adhesive composition according to any one of [1] to [6], wherein the high molecular weight polyol contains a polyoxyalkylene polyol having three hydroxy groups per molecule and a number average molecular weight of 4800 or more. [8] The urethane adhesive composition according to any one of [1] to [7], wherein the amount of the hydroxy groups of the low molecular weight polyol B is 3.0 to 90.0 mol% in the total amount of the hydroxy groups of the low molecular weight polyol A and the low molecular weight polyol B. [9] The urethane adhesive composition according to any one of [1] to [8], wherein the molar ratio of the isocyanate-reactive groups in the curing agent to all the isocyanate groups in the main agent (isocyanate-reactive groups / NCO) is 0.8 to 1.1.

[10] The urethane adhesive composition according to any one of [1] to [9], wherein the amount of the hydroxy groups of the low molecular weight polyol B is 30 to 90 mol% in the total amount of the hydroxy groups of the high molecular weight polyol and the low molecular weight polyol B.

[11] The urethane adhesive composition according to any one of [1] to

[10] , wherein the elastic modulus after complete curing is 15 MPa or more.

Advantages of the Invention

[0009] Even if the mixing ratio of the main agent and the curing agent of the urethane adhesive composition of the present invention deviates from the designed range, a decrease in the physical properties of the resulting cured product can be suppressed.

Modes for Carrying Out the Invention

[0010] The present invention will be described in detail below. In this specification, a numerical range represented using "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In this specification, unless otherwise specified, the production method of each component is not particularly limited. For example, conventionally known methods can be mentioned. In this specification, unless otherwise specified, each component can be used alone or in combination of two or more of the substances corresponding to the component. When a component contains two or more substances, the content of the component means the total content of the two or more substances. In this specification, there are cases where the effect of the present invention is said to be more excellent in that a decrease in the physical properties of the cured product obtained even when the mixing ratio of the main agent and the curing agent deviates from the designed range can be more suppressed.

[0011] [Urethane Adhesive Composition] The urethane adhesive composition (the composition of the present invention) of the present invention is A two-component urethane adhesive composition having a main agent and a curing agent, wherein the main agent contains a polyisocyanate component, and the isocyanate group content in the main agent is 5% by mass or more based on the total amount of the main agent, the curing agent contains a compound having a plurality of active hydrogen-containing groups in one molecule, the compound having a plurality of active hydrogen-containing groups in one molecule, a high molecular weight polyol having 2 to 3 hydroxy groups per molecule and a number average molecular weight of 1800 or more, a low molecular weight polyol A having 2 hydroxy groups per molecule and a number average molecular weight of 200 or less, a low molecular weight polyol B having 3 hydroxy groups per molecule, at least one or all of the 3 hydroxy groups being secondary hydroxy groups, and a number average molecular weight of 1200 or less, and is a urethane adhesive composition.

[0012] Hereinafter, the composition of the present invention will be described in detail. The composition of the present invention is a two-component urethane adhesive composition having a main agent and a curing agent. The curing agent contained in the composition of the present invention refers to a curing agent in a broad sense. The curing agent (in a broad sense) contained in the composition of the present invention includes a curing agent (in a narrow sense) that reacts with the polyisocyanate component contained in the main agent.

[0013] <<Main agent>> In the present invention, the main agent contains a polyisocyanate component. <Polyisocyanate component> In the present invention, the polyisocyanate component contained in the main agent is a compound having a plurality of isocyanate groups in one molecule. Examples of the polyisocyanate component include urethane prepolymers and polyisocyanates that can be used in the production of urethane prepolymers.

[0014] (Polyisocyanate: Polyisocyanate component) In this specification, the polyisocyanate as the polyisocyanate component has a plurality of isocyanate groups in one molecule and refers to a low-molecular-weight compound. Note that urethane prepolymers are excluded from the above polyisocyanate. Examples of the above polyisocyanate include toluene diisocyanate (TDI), diphenylmethane diisocyanate (unsubstituted MDI, also referred to as pure MDI or monomeric MDI), 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), triphenylmethane triisocyanate, polymeric MDI (a compound obtained by increasing the molecular weight of diphenylmethane diisocyanate (pure MDI)), modified MDI (e.g., isocyanurate-modified MDI (trimer of MDI), carbodiimide-modified MDI, urethane-modified MDI, etc., obtained by modifying diphenylmethane diisocyanate (pure MDI)), and other aromatic polyisocyanates; hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanate (NBDI), trans-cyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), bis(isocyanatomethyl)cyclohexane (H 6 XDI), dicyclohexylmethane diisocyanate (H 12 MDI), and aliphatic and / or alicyclic polyisocyanates such as carbodiimide-modified products and isocyanurate-modified products of these. Note that the above polymeric MDI is not included in the above modified MDI.

[0015] (urethane prepolymer) The urethane prepolymer as the polyisocyanate component is a urethane-based compound having a plurality of isocyanate groups in one molecule. In the urethane prepolymer, the position where the isocyanate group binds is not particularly limited, but one preferred embodiment is that the isocyanate group binds to the terminal of the urethane prepolymer.

[0016] Examples of the urethane prepolymer include those conventionally known. Specifically, for example, a reaction product obtained by reacting a polyisocyanate and a compound having a plurality of active hydrogen-containing groups in one molecule (hereinafter sometimes referred to as an "active hydrogen compound") so that the isocyanate group is in excess with respect to the active hydrogen-containing group can be used.

[0017] ·Active hydrogen-containing group In the present invention, the active hydrogen-containing group means a group containing active hydrogen. Examples of the active hydrogen-containing group include a hydroxy group, an amino group, and an imino group.

[0018] ·Polyisocyanate (raw material of urethane prepolymer) The polyisocyanate that can be used in the production of the urethane prepolymer is not particularly limited as long as it has a plurality of isocyanate groups in the molecule. For example, the same compounds as those described above in "(Polyisocyanate: Polyisocyanate component)" can be mentioned.

[0019] From the viewpoint that the effects of the present invention are more excellent, the polyisocyanate that can be used to produce the urethane prepolymer is preferably an aromatic polyisocyanate, more preferably contains at least one selected from the group consisting of diphenylmethane diisocyanate (pure MDI), polymeric MDI, and modified MDI, and more preferably contains diphenylmethane diisocyanate (pure MDI) or modified MDI.

[0020] ·Active hydrogen compound (raw material of urethane prepolymer) The compound (active hydrogen compound) having a plurality of active hydrogen-containing groups in one molecule that can be used in the production of the urethane prepolymer is not particularly limited. Examples of the active hydrogen-containing group include a hydroxyl (OH) group, an amino group, and an imino group.

[0021] Examples of the active hydrogen compound as a raw material for the urethane prepolymer preferably include a polyol compound having a plurality of hydroxyl (OH) groups in one molecule, a polyamine compound having a plurality of amino groups and / or imino groups in one molecule, and the like. Among them, a polyol compound is preferable.

[0022] The above polyol compound is not particularly limited as long as it is a compound having a plurality of OH groups. Specific examples of the polyol compound include polyether polyol; polyester polyol; (meth)acrylic polyol; polybutadiene polyol, hydrogenated polybutadiene polyol; low molecular weight polyhydric alcohols; and mixed polyols thereof. Among them, polyether polyol is mentioned as one of the preferable embodiments.

[0023] The polyether polyol is not particularly limited as long as it has a polyether as the main chain and has a plurality of hydroxy groups. The polyether is a group having a plurality of ether bonds, and specific examples thereof include, for example, the structural unit -R a -O-R b - and a group having a plurality of them in total. Here, in the above structural unit, R a and R b each independently represent a hydrocarbon group. The hydrocarbon group is not particularly limited. For example, a linear alkylene group having 1 to 10 carbon atoms can be mentioned. Examples of the polyether polyol include polyoxyethylene diol (polyethylene glycol); polyoxypropylene diol (polypropylene glycol: PPG); polyoxypropylene triol; polyoxyalkylene tetraol; polyol of a copolymer of ethylene oxide / propylene oxide; polytetramethylene ether glycol (PTMEG), polytetraethylene glycol, sorbitol-based polyol, and the like. From the viewpoint of excellent compatibility with polyisocyanate, polypropylene glycol and polyoxypropylene triol are preferred as the polyether polyol that can be used in the production of the urethane prepolymer.

[0024] From the viewpoint that the effect of the present invention is more excellent and the elongation at break of the obtained cured product is high, the weight average molecular weight of the active hydrogen compound (for example, polyether polyol) as a raw material of the urethane prepolymer is preferably 500 to 20,000, and more preferably 4,800 to 12,000. In the present invention, the number average molecular weight of the active hydrogen compound can be obtained as a standard polystyrene conversion value obtained by gel permeation chromatography (GPC) measurement under the following conditions. · Solvent: Tetrahydrofuran · Detector: RI detector

[0025] (Preferred embodiments of the polyisocyanate component) From the viewpoint that the effect of the present invention is more excellent and the adhesion expression performance (the speed at which adhesion is expressed. The same applies hereinafter) and the physical properties of the obtained cured product (for example, elongation at break) are excellent, the polyisocyanate component preferably contains at least one selected from the group consisting of urethane prepolymer, diphenylmethane diisocyanate, polymeric MDI, and modified MDI, and more preferably contains a urethane prepolymer and at least one polyisocyanate selected from the group consisting of diphenylmethane diisocyanate, polymeric MDI, and modified MDI.

[0026] · Method for producing the polyisocyanate component The method for producing the polyisocyanate component is not particularly limited. For example, when the polyisocyanate component contains at least a urethane prepolymer, the polyisocyanate (raw material) is used in an amount such that the number of isocyanate groups is 1.5 to 25.0 moles per mole of the active hydrogen-containing groups of the active hydrogen compound (raw material), and these are mixed and reacted under conditions such as 60 to 100 °C to produce a polyisocyanate component containing at least a urethane prepolymer. A plasticizer may be further used in the above production method. When the polyisocyanate component contains at least a urethane prepolymer, the amounts of the active hydrogen compound and the polyisocyanate used as raw materials in the production method of the polyisocyanate component can be reflected in the amount of the obtained polyisocyanate component (which may further contain unreacted polyisocyanate in addition to the urethane prepolymer). Further, polyisocyanate may be separately added to the above polyisocyanate component after production.

[0027] <Isocyanate group content in the main agent> In the present invention, the isocyanate group content in the main agent is 5% by mass or more in the total amount of the main agent. By having the isocyanate group content as described above, the effects of the present invention are excellent, and the adhesive strength and elastic modulus of the obtained cured product can be increased. The isocyanate group content in the main agent is the mass percentage of the amount of the isocyanate groups of the polyisocyanate component contained in the main agent with respect to the total amount of the main agent. From the viewpoint that the effects of the present invention are more excellent, the adhesive strength and elastic modulus of the obtained cured product can be increased, and the adhesive development performance is excellent, the isocyanate group content in the main agent is preferably 5 to 25% by mass, more preferably 8 to 20% by mass in the total amount of the main agent.

[0028] ·Calculation method of isocyanate group content in the main agent (total amount) The isocyanate group content in the main agent can be calculated as follows: First, measure the isocyanate group content ratio (mass %) in the polyisocyanate component (for example, a urethane prepolymer that may further contain unreacted polyisocyanate) using the potentiometric titration apparatus according to Method A in accordance with JIS K-1603-1:2007. Then, apply the above measurement results and the like to the following formula to calculate the isocyanate group content (mass %) in the main agent. (Formula) Isocyanate group content (mass %) in the total amount of the main agent = V × W / X × 100 [V] Isocyanate group content ratio (mass %) in the polyisocyanate component [W] Amount (parts by mass) of the polyisocyanate component used in the main agent [X] Total amount of the main agent (parts by mass)

[0029] <<Hardener>> In the present invention, the (broadly defined) hardener possessed by the composition of the present invention includes, as a narrowly defined hardener, a compound having a plurality of active hydrogen-containing groups in one molecule. The narrowly defined hardener has a functional group (isocyanate-reactive group) capable of reacting with an isocyanate group. Examples of the isocyanate-reactive group include a hydroxy group, an amino group, and an imino group.

[0030] In the present invention, the compound having a plurality of active hydrogen-containing groups in one molecule (as a narrowly defined hardener) is a high molecular weight polyol having 2 to 3 hydroxy groups per molecule and a number average molecular weight of 1800 or more, a low molecular weight polyol A having 2 hydroxy groups per molecule and a number average molecular weight of 200 or less, a low molecular weight polyol B having 3 hydroxy groups per molecule, at least one or all of the above 3 hydroxy groups being secondary hydroxy groups, and a number average molecular weight of 1200 or less. Since the composition of the present invention contains the above three types of polyols (high molecular weight polyol, low molecular weight polyols A, B), the effects of the present invention are excellent. In the present invention, the high molecular weight polyol does not contain the low molecular weight polyol A or B. Further, the low molecular weight polyol A does not contain the low molecular weight polyol B. The low molecular weight polyol B does not contain the low molecular weight polyol BA.

[0031] <High molecular weight polyol> In the present invention, the high molecular weight polyol included as one of the curing agents in the narrow sense is a compound having 2 to 3 hydroxy groups per molecule and a number average molecular weight of 1800 or more. By containing the above high molecular weight polyol, the composition of the present invention has excellent effects of the present invention. Further, the physical properties of the obtained cured product (for example, elastic modulus, elongation at break) can be improved.

[0032] <Hydroxy group> From the viewpoint that the high molecular weight polyol has more excellent effects of the present invention and the physical properties of the obtained cured product (for example, elastic modulus, elongation at break) are excellent, it preferably has 3 hydroxy groups per molecule.

[0033] <Number average molecular weight of high molecular weight polyol> From the viewpoint that the effects of the present invention are more excellent, the adhesive expression performance, and the physical properties of the obtained cured product (for example, elastic modulus, elongation at break) are excellent, the number average molecular weight of the above high molecular weight polyol is preferably 3000 to 20000, more preferably 4800 to 12000.

[0034] In the present invention, the number average molecular weight of the polyol (for example, high molecular weight polyol, low molecular weight polyols A and B) as the curing agent in the narrow sense can be the standard polystyrene conversion value obtained by gel permeation chromatography (GPC) measurement under the following conditions. · Solvent: Tetrahydrofuran · Detector: RI detector

[0035] From the viewpoint that the high molecular weight polyol provides more excellent effects of the present invention and the physical properties of the resulting cured product (e.g., elastic modulus, elongation at break) are excellent, it preferably contains polyoxyalkylene polyol (polyoxyalkylene triol), more preferably contains polyoxypropylene triol, and even more preferably contains a triol of an oxypropylene·oxyethylene copolymer having an oxyethylene group in addition to the oxypropylene group as a repeating unit that can form the main chain.

[0036] From the viewpoint that the high molecular weight polyol provides more excellent effects of the present invention, excellent adhesion expression performance, and excellent physical properties of the resulting cured product (e.g., elastic modulus, elongation at break), it preferably contains polyoxyalkylene polyol (polyoxyalkylene triol) having 3 hydroxy groups per molecule and a number average molecular weight of 3000 or more. More preferably, it contains polyoxypropylene triol having 3 hydroxy groups per molecule and a number average molecular weight of 4800 to 20000. Further, the above polyoxypropylene triol preferably has an oxyethylene group in addition to the oxypropylene group as a repeating unit that can form the main chain.

[0037] <Low molecular weight polyol A> In the present invention, the low molecular weight polyol A included as one of the curing agents in the narrow sense is a compound having 2 hydroxy groups per molecule and a number average molecular weight of 200 or less. The low molecular weight polyol A is a diol having 2 hydroxy groups per molecule.

[0038] <Number average molecular weight of low molecular weight polyol A> In the present invention, the number average molecular weight of the low molecular weight polyol A is 200 or less. From the viewpoint that the effects of the present invention are more excellent, the adhesion expression performance and the physical properties of the resulting cured product (e.g., elongation at break) are excellent, the number average molecular weight of the low molecular weight polyol A is preferably 48 to 150.

[0039] <Two hydroxy groups> · Linking group (skeleton of low molecular weight polyol A) In the low molecular weight polyol A, the above hydroxy group can be bonded to a divalent linking group. From the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, the divalent linking group is preferably a divalent alkylene group.

[0040] In the low molecular weight polyol A, the two hydroxy groups may be bonded to any carbon atom of the divalent alkylene group, and it is more preferable to bond to both ends of the linear alkylene group. Examples of the hydroxy group of the low molecular weight polyol A include primary and secondary hydroxy groups. In the present specification, the secondary hydroxy group is OH bonded to C in C-C ** H-C ** The primary hydroxy group is OH bonded to C in -C * H 2 The C in * is OH bonded to C.

[0041] From the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, the low molecular weight polyol A preferably contains a compound in which hydroxy groups are bonded to both ends of a linear alkylene group.

[0042] From the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, the low molecular weight polyol A preferably contains an alkanediol. The alkanediol is a compound in which two hydroxy groups are bonded to a divalent alkylene group. Similar to the low molecular weight polyol A, in the case of alkanediol, the two hydroxy groups may be bonded to any carbon atom of the divalent alkylene group, or preferably bonded to both ends of the linear alkylene group (in this case, the hydroxy group is a primary hydroxy group). Also, similar to the low molecular weight polyol A, the alkanediol preferably includes a compound in which hydroxy groups are bonded to both ends of the linear alkylene group.

[0043] Examples of the alkanediol include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, and octanediol.

[0044] The low molecular weight polyol A (for example, alkanediol) preferably contains butanediol, and more preferably contains 1,4 - butanediol, from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent.

[0045] <Low molecular weight polyol B> In the present invention, the low molecular weight polyol B included as one of the curing agents in the narrow sense is a compound having three hydroxy groups per molecule, at least one or all of the three hydroxy groups being secondary hydroxy groups, and having a number average molecular weight of 1200 or less. The low molecular weight polyol B is a triol having three hydroxy groups per molecule.

[0046] <Number average molecular weight of low molecular weight polyol B> In the present invention, the number average molecular weight of the low molecular weight polyol B is 1200 or less. The number average molecular weight of the low molecular weight polyol B is preferably 80 to 1200 from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent. When the low molecular weight polyol B contains the aliphatic hydrocarbon triol B1 described below, the number average molecular weight of the aliphatic hydrocarbon triol B1 is preferably 80 to 300 from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent. When the low molecular weight polyol B contains the polyoxyalkylene triol B2 described below, the number average molecular weight of the polyoxyalkylene triol B2 is preferably 500 to 1200 from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent.

[0047] <Secondary hydroxy group> In the present invention, at least one or all of the three hydroxy groups of the low molecular weight polyol B are secondary hydroxy groups, that is, C-C ** The C in H-C ** is the OH bonded to it. The low molecular weight polyol B can have 1, 2 or 3 secondary hydroxy groups per molecule. When the low molecular weight polyol B contains the aliphatic hydrocarbon triol B1 described below, the aliphatic hydrocarbon triol B1 preferably has 1 secondary hydroxy group from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent. When the low molecular weight polyol B contains the polyoxyalkylene triol B2 described below, the polyoxyalkylene triol B2 preferably has 3 secondary hydroxy groups from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent.

[0048] (Primary hydroxy group) When the low molecular weight polyol B has 1 or 2 secondary hydroxy groups, the remaining hydroxy groups are not particularly limited. However, the remaining hydroxy groups are not secondary hydroxy groups. The remaining hydroxy groups are primary hydroxy groups (-C * H 2 The C in *One of the preferred embodiments is that it is OH) bonded to

[0049] (Linking group: skeleton of low molecular weight polyol B) In the low molecular weight polyol B, the above three hydroxy groups can be bonded to a trivalent linking group. From the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, the above trivalent linking group is a trivalent aliphatic hydrocarbon group (residue obtained by removing three hydrogen atoms from an aliphatic hydrocarbon), or a trivalent polyoxyalkylene group.

[0050] ·Trivalent aliphatic hydrocarbon group The number of carbon atoms of the trivalent aliphatic hydrocarbon group is 3 or more, and from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, 3 to 6 are preferable. The trivalent aliphatic hydrocarbon group as the linking group of the low molecular weight polyol B may be either saturated or unsaturated, and may be linear, branched, cyclic, or any combination thereof. When the linking group is a trivalent aliphatic hydrocarbon group, one of the preferred embodiments is that the linking group is a trivalent linear saturated aliphatic hydrocarbon group.

[0051] ·Trivalent polyoxyalkylene group In the trivalent polyoxyalkylene group as the linking group of the low molecular weight polyol B, the oxyalkylene group that can constitute the polyoxyalkylene group is not particularly limited. For example, oxyalkylene groups having 2 to 6 carbon atoms such as oxyethylene group and oxypropylene group can be mentioned.

[0052] ··-R-OH When the low-molecular-weight polyol B has a trivalent polyoxyalkylene group as a linking group, the three hydroxy groups in the low-molecular-weight polyol B each independently form -R-OH, where each R independently represents a divalent aliphatic hydrocarbon group, and at least one or all of the three hydroxy groups are secondary hydroxy groups, and it is preferable that each -R-OH is bonded to a trivalent polyoxyalkylene group, which is one of the preferable correspondences. In -R-OH, each R independently represents a divalent aliphatic hydrocarbon group. The divalent aliphatic hydrocarbon group may be either saturated or unsaturated, and may be linear, branched, cyclic, or any combination thereof. When R is a divalent aliphatic hydrocarbon group, one of the preferable embodiments is that R is a divalent branched saturated aliphatic hydrocarbon group. Examples of -R-OH when R is a divalent branched saturated aliphatic hydrocarbon group include, for example, -CH 2 -CH(CH 3 )-OH, -CH 2 -CH 2 -CH(CH 3 )-OH, -CH 2 -CH(OH)-CH 2 (CH 3 ) and the like.

[0053] In the low-molecular-weight polyol B, from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, it is preferable that the three hydroxy groups are bonded to a trivalent aliphatic hydrocarbon group.

[0054] From the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, the low-molecular-weight polyol B An aliphatic hydrocarbon triol B1 having three hydroxy groups per molecule and a trivalent aliphatic hydrocarbon group having 3 or more carbon atoms, wherein the three hydroxy groups are bonded to the trivalent aliphatic hydrocarbon group, and at least one or all of the three hydroxy groups are secondary hydroxy groups, and having a number average molecular weight of 1200 or less, and / or It preferably contains a polyoxyalkylene triol B2 having three hydroxy groups per molecule and a trivalent polyoxyalkylene group, wherein the three hydroxy groups each independently form -R-OH (wherein each R independently represents a divalent alkylene group), and at least one or all of the three hydroxy groups are secondary hydroxy groups, and the -R-OH is bonded to the trivalent polyoxyalkylene group, and having a number average molecular weight of 1200 or less. It is more preferable to contain an aliphatic hydrocarbon triol B1.

[0055] From the viewpoint that the aliphatic hydrocarbon triol B1 has more excellent effects of the present invention and excellent adhesion expression performance and physical properties of the obtained cured product (for example, elongation at break), it preferably contains a compound in which at least one hydroxy group is bonded to each of the carbon atoms at both ends of a linear trivalent aliphatic hydrocarbon group, and the remaining hydroxy groups are bonded to the carbon atoms other than the both ends in the aliphatic hydrocarbon group. The hydroxy groups bonded to the carbon atoms at both ends of the aliphatic hydrocarbon group correspond to primary hydroxy groups, and the remaining hydroxy groups at the carbon atoms other than the both ends correspond to secondary hydroxy groups.

[0056] Examples of the low molecular weight polyol B include aliphatic hydrocarbon triols B1 such as glycerin, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1,3,6-hexanetriol, and 1,2,8-octanetriol; Terminal -CH 2 -CH(CH 3 )-OH, and polyoxyalkylene triols B2 such as polyoxypropylene having three of them.

[0057] Aliphatic hydrocarbon triol B1 preferably contains glycerin and / or 1,2,4 - butanetriol, and more preferably contains glycerin, from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent.

[0058] (Amount of hydroxy groups of low - molecular - weight polyol B) · Among the total amount of hydroxy groups of low - molecular - weight polyols A and B The amount of hydroxy groups of low - molecular - weight polyol B, from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, is preferably 3.0 to 90.0 mol% in the total amount of hydroxy groups of low - molecular - weight polyol A and low - molecular - weight polyol B, more preferably 3.0 to 30.0 mol%, even more preferably 5.0 to 20.0 mol%, and still more preferably 8.0 to 15.0 mol%.

[0059] · Among the total amount of hydroxy groups of high - molecular - weight polyol and low - molecular - weight polyol B The amount of hydroxy groups of low - molecular - weight polyol B, from the viewpoint that the effects of the present invention are more excellent and the adhesion expression performance and the physical properties of the obtained cured product (for example, elongation at break) are excellent, is preferably 30 to 90 mol% in the total amount of hydroxy groups of the above - mentioned high - molecular - weight polyol and low - molecular - weight polyol B, more preferably 30 to 80 mol%, even more preferably 35 to 70 mol%, and still more preferably 45 to 60 mol%.

[0060] (Polyamine) The curing agent (in a broad sense) contained in the composition of the present invention preferably further contains polyamine as a curing agent in a narrow sense from the viewpoint that the effects of the present invention are more excellent. Polyamine is a compound having a plurality of amino groups (-NH 2 ) and / or imino groups (-NH -) in total per molecule. The polyamine has an amino group (-NH 2 ) and / or an imino group (-NH-) as an isocyanate-reactive group. Note that the above polyamine does not contain the catalyst described later.

[0061] Examples of the above polyamine include aliphatic polyamines such as diethylenetriamine, diethylaminopropylamine, and triethylenetetramine; aromatic polyamines such as diaminodiphenylmethane, diaminodiphenylsulfone, and benzidine; polyether polyamines (polyamines with a polyether main chain), and the like. Among them, polyether polyamines are preferred as the polyamine, and polyoxypropylene diamine is more preferred. Polyoxypropylene diamine is preferably a compound in which one amino group is bonded to each of both ends of polyoxypropylene.

[0062] · Content of polyamine When the curing agent further contains polyamine as a curing agent in the narrow sense, from the viewpoint of more excellent effects of the present invention, the content of polyamine is preferably 0.5 to 5.0% by mass in the total amount of the curing agent in the narrow sense.

[0063] (Catalyst) The curing agent contained in the composition of the present invention preferably further contains a catalyst. The catalyst is not particularly limited as long as it can promote the reaction of the isocyanate group. For example, metal catalysts such as organotin catalysts and organic bismuth catalysts; amine catalysts such as tertiary amine compounds can be mentioned. From the viewpoint of more excellent effects of the present invention and excellent adhesion expression performance and physical properties of the obtained cured product, the above catalyst preferably contains an organotin catalyst and / or an amine catalyst, and more preferably contains an organotin catalyst and an amine catalyst.

[0064] · Organotin catalyst When the catalyst contains an organotin catalyst, it is preferable because the adhesiveness at the initial stage when the main agent and the curing agent are mixed can be quickly developed. Examples of the organotin catalyst include dialkyltin dicarboxylates such as dibutyltin dilaurate, dibutyltin dioctate, dioctyltin diacetate, dioctyltin distearate, dioctyltin dilaurate; dialkyltin dialkoxides; divalent tin compounds such as tin octylate, tin naphthenate, tin stearate, tin ferulate; dialkyltin dialkyl mercaptides; dialkyltin bis(thioglycolate)s.

[0065] When the organotin catalyst has an alkyl group directly bonded to tin (for example, dialkyltin dicarboxylates, dialkyltin bis(thioglycolate)s, etc.), the number of carbon atoms of the above alkyl group is preferably 6 or more, more preferably 8 to 12.

[0066] In the organotin catalyst, from the viewpoint that the effects of the present invention are more excellent, it is preferable that the ligand coordinated to tin has a sulfur atom as the coordinating atom coordinated to the above tin. Examples of the compound having a sulfur atom as the above coordinating atom in the organotin catalyst include dialkyltin dialkyl mercaptides and dialkyltin bis(thioglycolate)s.

[0067] Examples of the dialkyltin dialkyl mercaptides include compounds represented by the following formula (2). (R 21 ) 2 -Sn-(S-R 22 ) 2 (2) In formula (2), R 21 , R 22 each independently represents an alkyl group. The two R 21 may be the same or different. The same applies to R 22 . The above alkyl group is not particularly limited. Examples of the dialkyltin dialkyl mercaptides include, specifically, dibutyltin dioctyl mercaptide, dioctyltin dioctyl mercaptide, dibutyltin didodecyl mercaptide, and dioctyltin didodecyl mercaptide.

[0068] Examples of the dialkyltin bis(thioglycolate) compounds include, for example, the compounds represented by the following formula (3). (R 31 ) 2 -Sn-(S-CH 2 -CO-O-R 32 ) 2 (3) In formula (3), R 31 , R 32 each independently represents an alkyl group. The two R 31 may be the same or different. The same applies to R 32 . The alkyl group is not particularly limited. Examples of the dialkyltin bis(thioglycolate) compounds include, specifically, dibutyltin bis(octylthioglycolate) and dioctyltin bis(octylthioglycolate).

[0069] From the viewpoint that the effects of the present invention are more excellent, the organotin catalyst is preferably an organotin catalyst in which the ligand coordinated to tin has a sulfur atom as the coordinating atom coordinated to the above tin, more preferably dialkyltin dialkyl mercaptides and / or dialkyltin bis(thioglycolate) compounds, still more preferably dialkyltin bis(thioglycolate) compounds, and even more preferably dioctyltin bis(octylthioglycolate).

[0070] · Amine-based catalyst Examples of the amine-based catalyst include, for example, tertiary amine compounds. The tertiary amine compound is a compound having a tertiary amino group (three carbon atoms are bonded to the nitrogen atom, and the nitrogen atom is not bonded to a hydrogen atom). Examples of the tertiary amine compound include 1,4-diazabicyclo[2.2.2]octane, 2,4,6-tris(dimethylaminomethyl)phenol, 2-methyltriethylenediamine, a compound containing a dimorpholinodiethyl ether structure, and the like.

[0071] From the viewpoint of excellent effects of the present invention, the tertiary amine compound preferably contains a dimorpholinodiethyl ether structure. The dimorpholinodiethyl ether structure is a structure having dimorpholinodiethyl ether as a basic skeleton. In the dimorpholinodiethyl ether structure, the hydrogen atom of the morpholine ring may be substituted with a substituent. The substituent is not particularly limited. For example, an alkyl group can be mentioned. Examples of the alkyl group include a methyl group and an ethyl group.

[0072] Examples of the amine-based catalyst containing a dimorpholinodiethyl ether structure include a compound represented by the following formula (9).

Chemical formula

[0073] From the viewpoint of more excellent effects of the present invention, the content of the catalyst (when the catalyst contains a plurality of types of compounds, the total content of the plurality of types of compounds) is preferably 0.001 to 1.0% by mass based on the total amount of the curing agent of the composition of the present invention.

[0074] When the catalyst contains an organotin catalyst and an amine-based catalyst, from the viewpoint that the effects of the present invention are more excellent, the mass ratio of the organotin catalyst to the amine-based catalyst is preferably such that the content of the amine-based catalyst is 1 to 100 parts by mass with respect to 1 part by mass of the organotin catalyst.

[0075] (Other components) The urethane adhesive composition of the present invention can further contain an additive as long as it does not impair the object of the present invention. Examples of the above additive include a plasticizer, a filler, a silane coupling agent, an adhesive, an anti-aging agent, an antioxidant, a pigment, a thixotropic agent, an ultraviolet absorber, a flame retardant, a surfactant, a dispersant, a dehydrating agent such as zeolite, an antistatic agent, and the like. The amount of the additive can be determined appropriately. Each of the above additives can be added to the main agent and / or the curing agent.

[0076] (Filler) The composition of the present invention can further contain a filler in the main agent and / or the curing agent. The filler does not include zeolite described later. Examples of the filler include carbon black, calcium carbonate, clay, silica, and talc. The above filler may be surface-treated with a surface treatment agent such as a fatty acid, a resin acid, a urethane compound, or a fatty acid ester. From the viewpoint that the effects of the present invention are more excellent, carbon black and / or clay are preferable as the filler. Carbon black and clay are not particularly limited. For example, conventionally known ones can be mentioned.

[0077] ·Content of filler When the main agent further contains a filler, the content of the filler in the main agent is preferably 10 to 60% in the total amount of the main agent, and more preferably 15 to 50% by mass, from the viewpoint that the effects of the present invention are more excellent. When the curing agent contained in the composition of the present invention further contains a filler, the content of the filler in the curing agent is preferably 10 to 60% in the total amount of the curing agent, more preferably 25 to 45% by mass, from the viewpoint that the effects of the present invention are more excellent.

[0078] (Zeolite) The composition of the present invention can further contain zeolite. By further containing zeolite in the composition of the present invention, moisture in the system can be absorbed, and the reaction between the isocyanate group and water in the polyisocyanate component can be suppressed at the initial stage when the main agent and the curing agent are mixed. When the curing agent contained in the composition of the present invention further contains zeolite, it is cited as one of the preferred embodiments. Zeolite is a general term for crystalline aluminosilicates, but zeolite is not particularly limited in the present invention. For example, those known in the art can be cited.

[0079] · Content of zeolite When the curing agent contained in the composition of the present invention further contains zeolite, the content of zeolite is preferably 3% by mass or more in the total amount of the curing agent, more preferably 4 to 10% by mass, from the viewpoint that the effects of the present invention are more excellent.

[0080] (Preparation of main agent) The main agent contained in the composition of the present invention can be prepared, for example, by mixing the above essential components and additives that can be further used as necessary.

[0081] (Preparation of curing agent) The curing agent contained in the composition of the present invention can be prepared, for example, by mixing the above essential components and catalysts and additives that can be further used as necessary.

[0082] (Method of use) When using the composition of the present invention, the main agent and the curing agent can be mixed at a mixing ratio (volume ratio) of isocyanate-reactive group / NCO, which will be described later.

[0083] Volume ratio of main agent to curing agent In the present invention, when using the composition of the present invention, from the viewpoint that the effects of the present invention are more excellent, the adhesive expression performance and the physical properties of the obtained cured product are excellent, it is preferable to use the main agent and the curing agent such that the volume ratio of the main agent to the curing agent is 1.0:1.0 or less. In this specification, the case where the volume ratio of the main agent to the curing agent is 1.0:1.0 is referred to as the normal mixing ratio, and the case where the above volume ratio exceeds 1.0:1.0 is referred to as the abnormal mixing ratio. In the present invention, when the above volume ratio is less than 1.0:1.0, it can be made to conform to the normal mixing ratio.

[0084] (Isocyanate-reactive group / NCO) In this specification, the molar ratio of the isocyanate-reactive groups in the curing agent (or the curing agent in the narrow sense) of the composition of the present invention to all the isocyanate groups in the main agent may be referred to as "isocyanate-reactive group / NCO". In the use of the composition of the present invention, from the viewpoint of the effects of the present invention, the isocyanate-reactive group / NCO can be, for example, 1.1 or less.

[0085] Regarding the composition of the present invention, the isocyanate-reactive group / NCO (for example, the isocyanate-reactive group / NCO when using the composition of the present invention) is preferably 0.8 to 1.1, and more preferably 0.9 to 1.05, from the viewpoint that the effects of the present invention are more excellent, the adhesive expression performance and the physical properties (particularly the elastic modulus) of the obtained cured product are excellent.

[0086] Relationship between the volume ratio of the main agent to the curing agent and the isocyanate-reactive group / NCO In the two-liquid state before use of the composition of the present invention, when the volume ratio of the main agent to the curing agent is the normal mixing ratio, the isocyanate-reactive group / NCO is preferably 1.0 or less, and more preferably 0.8 to 1.0, from the viewpoint that the composition of the present invention is manufactured as designed, the effects of the present invention are more excellent, and the adhesive expression performance and the physical properties of the obtained cured product are excellent.

[0087] In addition, in the use of the composition of the present invention, from the perspective of the effects of the present invention, the upper limit of the isocyanate-reactive group / NCO can be set to 1.1 or less when the volume ratio of the main agent to the curing agent (main agent: curing agent) is 1.0:1.1 or less. In the use of the composition of the present invention, from the perspective that the effects of the present invention are more excellent, the adhesion expression performance and the physical properties of the obtained cured product are excellent, it is preferable that the isocyanate-reactive group / NCO is 0.95 to 1.1 when the above volume ratio is 1.0:0.9 to 1.1.

[0088] Examples of the base material to which the composition of the present invention can be applied include plastics, glass, rubber, metals (including coated plates and electrodeposited steel plates), and the like. Examples of the plastic include polymers of propylene, ethylene, and cycloolefin-based monomers. The above polymers may be homopolymers, copolymers, or hydrogenated products. Specific examples of plastics include olefin resins such as polypropylene and polyethylene, polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polymethyl methacrylate resin (PMMA resin), polycarbonate resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyvinyl chloride resin, acetate resin, ABS resin (acrylonitrile-butadiene-styrene resin), and polyamide resin, which are difficult-to-adhere resins. The base material may be surface-treated. Examples of the surface treatment include flame treatment, corona treatment, itro treatment, and primer treatment. These treatments are not particularly limited. For example, conventionally known ones can be mentioned. The method for applying the composition of the present invention to the base material is not particularly limited. For example, conventionally known ones can be mentioned.

[0089] ·Curing conditions The composition of the present invention can be cured by mixing the main agent and the curing agent. After mixing the main agent and the curing agent as described above, the obtained mixture can be cured. Examples of the curing conditions include a relative humidity of 20 to 80% RH and a temperature of 5 to 45°C.

[0090] The composition of the present invention can be a cured product of a polyurethane type after curing.

[0091] ·Elastic modulus after complete curing From the viewpoint that the effects of the present invention are more excellent, the elastic modulus of the cured product after completely curing the composition of the present invention is preferably 15 MPa or more, and more preferably 20 to 300 MPa. In the present invention, it is assumed that the composition of the present invention can be completely cured by leaving the composition of the present invention under the conditions of 23°C and 50% relative humidity for 7 days. As described above, the elastic modulus of the cured product obtained by completely curing the composition of the present invention is the tensile elastic modulus (unit: MPa) measured by performing a tensile test (tensile speed: 200 mm / min) in accordance with JIS K6850:1999 under the condition of 23°C.

Examples

[0092] The present invention will be specifically described below with reference to examples. However, the present invention is not limited thereto.

[0093] <Main agent> ·Preparation of urethane prepolymer 1 A mixture of polyol 1-1 (100 parts by mass) and polyisocyanate A-1 (168.8 parts by mass) was reacted at 80°C for 5 hours to prepare urethane prepolymer 1 (polyisocyanate component). In the preparation of the above urethane prepolymer 1, the molar ratio (NCO group / OH group) of the isocyanate groups of polyisocyanate A-1 to the total of the hydroxy groups of polyol 1-1 was 1.99. The urethane prepolymer 1 prepared as described above was directly used for the preparation of the following main agent.

[0094] ·Preparation of main agent To the urethane prepolymer 1 prepared as described above, filler 1 (67.2 parts by mass) was added, and these were mixed with a stirrer to produce a main agent. The main agent produced as described above is referred to as main agent formulation number 1.

[0095] · Preparation of urethane prepolymer 2 A mixture of polyol 1-1 (100 parts by mass), plasticizer DINP (67.5 parts by mass), and polyisocyanate A-1 (112.4 parts by mass) was reacted at 80 °C for 5 hours to prepare urethane prepolymer 2 (polyisocyanate component). In the preparation of the above urethane prepolymer 2, the molar ratio (NCO group / OH group) of the isocyanate groups of polyisocyanate A-1 to the total number of hydroxy groups of polyol 1-1 was 1.33. The urethane prepolymer 2 prepared as described above was used as it was in the preparation of the following main agent.

[0096] · Preparation of main agent To the urethane prepolymer 2 prepared as described above, filler 1 (70.0 parts by mass) was added, and these were mixed with a stirrer to produce a main agent. The main agent produced as described above is referred to as main agent formulation number 2.

[0097] Details of each component used in the preparation of the above main agent are as follows. (Polyol 1) · Polyol 1-1: Polyoxypropylene triol having 3 hydroxy groups per molecule and a number average molecular weight of 5000. EXCENOL 5030 manufactured by AGC Inc. (Polyisocyanate A) · Polyisocyanate A-1: Carbodiimide-modified MDI. Coronate MX manufactured by Tosoh Corporation. It has 2 isocyanate groups per molecule. · Plasticizer: DINP (diisononyl phthalate) · Filler 1: ISAF grade carbon black

[0098] (Calculation of isocyanate group content in the total amount of main agent) The isocyanate group content in the total amount of the above main agent was calculated by the above NCO amount calculation method. Regarding the urethane prepolymer 1 or 2 (polyisocyanate component) obtained in the preparation of the above urethane prepolymer, using a potentiometric titrator, the isocyanate group content rate (mass%) in the polyisocyanate component was measured by Method A in accordance with JIS K-1603-1:2007. The isocyanate group content rate in urethane prepolymer 1 was 17.3 mass%. From the above results, the isocyanate group content in the total amount of main agent formulation No. 1 was calculated to be 13.8 mass%. The isocyanate group content rate in urethane prepolymer 2 was 10.8 mass%. From the above results, the isocyanate group content in the total amount of main agent formulation No. 2 was calculated to be 8.6 mass%.

[0099] <Hardener> Using each component shown in the hardener column of the following Table 1 in the composition (parts by mass) shown in the same table, these were mixed with a stirrer to produce a hardener. Regarding hardener 9, in the column of "Ratio (mol%) of the amount of hydroxyl groups of low molecular weight polyol B in the total amount of hydroxyl groups of low molecular weight polyol A and low molecular weight polyol B", "Ratio (mol%) of the amount of hydroxyl groups of low molecular weight polyol B in the total amount of hydroxyl groups of low molecular weight polyol A and relatively low molecular weight polyol B" was described. Also, in the column of "Ratio (mol%) of the amount of hydroxyl groups of low molecular weight polyol B in the total amount of hydroxyl groups of high molecular weight polyol and low molecular weight polyol B" of hardener 9, "Ratio (mol%) of the amount of hydroxyl groups of low molecular weight polyol B in the total amount of hydroxyl groups of high molecular weight polyol and relatively low molecular weight polyol B" was described.

[0100] Details of each component shown in the hardener column of Table 1 are as follows. (High molecular weight polyol) · High molecular weight polyol: A polyoxyalkylene triol having 3 hydroxyl groups per molecule, a number average molecular weight of 6000, and ethylene oxide added to the terminal. PREMINOL 7001K manufactured by AGC Co., Ltd.

[0101] (Low molecular weight polyol A) · 1,4-Butanediol: manufactured by Mitsubishi Chemical Corporation (molecular weight 90) · 1,2-Ethylene glycol: manufactured by Tokyo Chemical Industry Co., Ltd. (molecular weight 62)

[0102] (Low molecular weight polyol B) · Glycerin: manufactured by Kao Corporation (molecular weight 92) · 1,2,4-Butanetriol: manufactured by Tokyo Chemical Industry Co., Ltd. (molecular weight 106) · Polyoxypropylene triol: polyoxypropylene triol having three secondary hydroxy groups per molecule and a number average molecular weight of 1000. EXCENOL 1030 manufactured by AGC Inc. · Comparative low molecular weight polyol B: trimethylolpropane

[0103] · Polyamine: polyoxypropylene-α,ω-diamine. JEFFAMINE D-400 manufactured by Huntsman Corporation

[0104] · Filler 2: clay

[0105] · Zeolite: A-type zeolite. "Zeolam A-4" manufactured by Tosoh Corporation

[0106] · Organotin catalyst: dioctyltin bis(octylthioglycolate) (the following structure). Neo-Stann U-860 manufactured by Nitto Kasei Co., Ltd.

Chemical formula

[0107] · Amine catalyst: DMDEE. Dimorpholinodiethyl ether (manufactured by San-Apro Ltd.). The following structure

Chemical formula

[0108] <Manufacture of two-component urethane adhesive composition> The main agent and the curing agent produced as described above were combined with each formulation number shown in the urethane adhesive composition column of Table 1, and these were used at two volume ratios, the normal mixing ratio and the abnormal mixing ratio, shown in Table 1, and were stirred and mixed under the conditions of 23°C and 50% relative humidity, respectively. For each of the Examples and Comparative Examples at the normal mixing ratio, the molar ratio of the content of isocyanate-reactive groups in the curing agent to the content of isocyanate groups in the main agent (isocyanate-reactive groups / NCO) is shown in the column of "Amount of NCO-reactive groups in the curing agent / Amount of NCO groups in the main agent at the normal mixing ratio". For each of the Examples and Comparative Examples at the abnormal mixing ratio, the molar ratio of the content of isocyanate-reactive groups in the curing agent to the content of isocyanate groups in the main agent is shown in the column of "Amount of NCO-reactive groups in the curing agent / Amount of NCO groups in the main agent at the abnormal mixing ratio".

[0109] <Evaluation> The following evaluations were performed on each of the urethane adhesive compositions mixed as described above. The results are shown in Table 1.

[0110] The curing conditions of the urethane adhesive composition are as follows. (Curing conditions) · Curing condition 1 Under curing condition 1, each urethane adhesive composition was left to cure at 23°C and 50% relative humidity for 24 hours. · Curing condition 2 (complete curing) Under curing condition 2, each of the above urethane adhesive compositions was left to cure at 23°C and 50% relative humidity for 7 days. In the present invention, the curing condition for complete curing is set as curing condition 2.

[0111] (Breaking physical properties) Each of the urethane adhesive compositions mixed as described above was cured under curing condition 2, and dumbbell-shaped No. 3 test pieces (thickness 2 mm) were cut out from the obtained cured products. Using each of the above test pieces, a tensile test was performed in accordance with JIS K6251:2017, and the dumbbell breaking strength, elongation at dumbbell break, and elastic modulus (tensile elastic modulus) were measured under the conditions of a temperature of 23°C and a crosshead speed (tensile speed) of 200 mm / min. Each result is shown in the dumbbell breaking strength in Table 1 *1 (normal mixing ratio), elongation at dumbbell break *5 (normal mixing ratio), elastic modulus *3 (normal mixing ratio), dumbbell breaking strength *2 (abnormal mixing ratio), elastic modulus *4 (abnormal mixing ratio).

[0112] ·Evaluation criteria ··Dumbbell breaking strength Dumbbell breaking strength *1 (normal mixing ratio) is preferably 15 MPa or more, and more preferably a value greater than 15 MPa. Dumbbell breaking strength *2 (abnormal mixing ratio) is the same.

[0113] ··Elongation at break In the present invention, when the main agent and the curing agent are mixed at the normal mixing ratio and the obtained mixture is completely cured under curing condition 2, the elongation at dumbbell break (the elongation at dumbbell break shown in Table 1 *5 ) was used to evaluate the elongation at break. The elongation at dumbbell break shown in Table 1 *5 If it was 60% or more, the elongation at break of the obtained cured product was evaluated as preferable. In the above case, when the elongation at dumbbell break *5 was 75% or more, the elongation at break of the obtained cured product was evaluated as more preferable.

[0114] ··Elastic modulus (tensile elastic modulus) Elastic modulus *3 (normal mixing ratio) is preferably 100 MPa or more, and a value greater than 100 MPa is more preferable. Elastic modulus *4 (abnormal mixing ratio) is the same.

[0115] [Evaluation of suppression of deterioration of physical properties due to deviation from mixing ratio] In the present invention, suppression of deterioration of physical properties due to deviation from the mixing ratio, which is an object of the present invention (suppression of deterioration of physical properties of a cured product obtained even when the mixing ratio of the main agent and the curing agent deviates from the designed range), was evaluated by the breaking strength reduction rate and the elastic modulus reduction rate. (Rate of decrease in breaking strength) The calculation formula for the rate of decrease in breaking strength is as follows. Rate of decrease in breaking strength (%) = (*1 - *2) / *1 × 100 *1: Dumbbell breaking strength in Table 1 *1 (Normal mixing ratio) *2: Dumbbell breaking strength in Table 1 *2 (Abnormal mixing ratio) In addition, when the value of *2 was greater than the value of *1, the rate of decrease in breaking strength was set to "0%".

[0116] (Rate of decrease in elastic modulus) The calculation formula for the rate of decrease in elastic modulus is as follows. Rate of decrease in elastic modulus (%) = (*3 - *4) / *3 × 100 *3: Elastic modulus in Table 1 *3 (Normal mixing ratio) *4: Elastic modulus in Table 1 *4 (Abnormal mixing ratio) In addition, when the value of *4 was greater than the value of *3, the rate of decrease in elastic modulus was set to "0%".

[0117] (Evaluation criteria) In the present invention, when both the rate of decrease in breaking strength and the rate of decrease in elastic modulus were 20% or less, it was evaluated that even if the mixing ratio of the main agent and the curing agent deviated from the design range, the decrease in the physical properties of the obtained cured product could be suppressed. In the above case, it was evaluated that the smaller the rate of decrease in breaking strength and / or the rate of decrease in elastic modulus was than 20%, the more the above decrease in the physical properties of the obtained cured product could be suppressed. On the other hand, when the rate of decrease in breaking strength or the rate of decrease in elastic modulus exceeded 20%, it was evaluated that when the mixing ratio of the main agent and the curing agent deviated from the design range, the decrease in the physical properties of the obtained cured product could not be suppressed.

[0118] ((Evaluation of adhesive performance expression)) (Shear adhesive strength) · Preparation of test specimens Two adherends (width: 25 mm, length: 70 mm, thickness: 1.6 mm) made of electrodeposited coated plates (product name of the electrodeposition paint: GT-10LF, manufactured by Kansai Paint Co., Ltd.) were prepared. Next, on the surface of one adherend, each urethane adhesive composition immediately after preparation (mixing) was applied so as to have a width of 25 mm (adjusted to 25 mm according to the width of the adherend) and a length of 10 mm (10 mm in the longitudinal direction of the adherend). After that, the said adherend was bonded to the other adherend, and pressure bonding was performed so that the thickness of each adhesive composition became 2 mm to prepare test specimens. Each test specimen prepared as described above was cured under curing condition 1 or 2.

[0119] · Shear test For each test specimen cured as described above, a tensile test (tensile speed: 50 mm / min) was performed in accordance with JIS K6850:1999 under the condition of 23°C to measure the shear adhesion strength.

[0120] (Shear adhesion hardness expression rate) Based on the shear adhesion hardness expression rate (%) at the normal mixing ratio, the adhesion expression performance was evaluated. Each urethane adhesive composition was mixed at the normal mixing ratio to obtain each mixture. After each mixture was completely cured under curing condition 2, the percentage of the shear adhesion hardness after curing under curing condition 1 to the shear adhesion hardness after curing under curing condition 2 was calculated, and this was taken as the shear adhesion hardness expression rate. Shear adhesion hardness expression rate (%) = Shear adhesion hardness after curing under curing condition 1 / Shear adhesion hardness after complete curing under curing condition 2 × 100

[0121] (Evaluation criteria) In the present invention, when the shear adhesion hardness expression rate was 60% or more, it was evaluated that the speed of adhesion expression was at a usable level. When the shear adhesion hardness expression rate was 80% or more, it was evaluated that the adhesion expression performance was preferable. When the shear adhesion hardness expression rate was 90% or more, it was evaluated that the adhesion expression performance was more preferable. On the other hand, when the shear adhesion hardness expression rate was less than 60%, it was evaluated that the adhesion expression performance was poor.

[0122] [Table 1]

[0123]

Table 2

[0124] From the results shown in Table 1, in Comparative Example 1 where the curing agent does not contain low molecular weight polyol B, when the mixing ratio of the main agent and the curing agent deviated from the designed range, the deterioration of the physical properties of the resulting cured product could not be suppressed. In Comparative Example 2 where the curing agent does not contain low molecular weight polyol B and instead contains trimethylolpropane (having no secondary hydroxy group), when the mixing ratio of the main agent and the curing agent deviated from the designed range, the deterioration of the physical properties of the resulting cured product could not be suppressed. In Comparative Example 3 where the curing agent does not contain a predetermined high molecular weight polyol, when the mixing ratio of the main agent and the curing agent deviated from the designed range, the deterioration of the physical properties of the resulting cured product could not be suppressed.

[0125] In contrast, with the urethane adhesive composition of the present invention, even when the mixing ratio of the main agent and the curing agent deviated from the designed range, the deterioration of the physical properties of the resulting cured product could be suppressed. Also, in the urethane adhesive composition of the present invention, in Examples 1 to 3 and 5 to 9 where the amount of NCO-reactive groups in the curing agent / amount of NCO groups in the main agent (molar ratio) at the normal mixing ratio was 0.90 or more, the adhesion development was faster and the adhesion development performance was superior than in Example 4.

Claims

1. A two-component urethane adhesive composition comprising a main agent and a curing agent, wherein the main agent contains a polyisocyanate component, and the isocyanate group content in the main agent is 5% by mass or more based on the total amount of the main agent, the curing agent contains a compound having a plurality of active hydrogen-containing groups in one molecule, the compound having a plurality of active hydrogen-containing groups in one molecule contains a high molecular weight polyol having 3 hydroxy groups per molecule and a number average molecular weight of 4800 or more (however, excluding those in which polyhydrazodicarboxamide is dispersed in the hydroxyl group-containing compound), a low molecular weight polyol A having 2 hydroxy groups per molecule and a number average molecular weight of 200 or less, and a low molecular weight polyol B having 3 hydroxy groups per molecule, at least one or all of the 3 hydroxy groups being secondary hydroxy groups and having a number average molecular weight of 1200 or less, wherein the molar ratio (isocyanate-reactive group / NCO) of the isocyanate-reactive groups in the curing agent to all the isocyanate groups in the main agent is 0.8 to 1.

1.

2. The low molecular weight polyol B has 3 hydroxy groups per molecule and a trivalent aliphatic hydrocarbon group having 3 or more carbon atoms, the 3 hydroxy groups are bonded to the trivalent aliphatic hydrocarbon group, and at least one or all of the 3 hydroxy groups are secondary hydroxy groups and have a number average molecular weight of 1200 or less, an aliphatic hydrocarbon-based triol B1, and / or has 3 hydroxy groups per molecule and a trivalent polyoxyalkylene group, each of the 3 hydroxy groups independently forms -R-OH, each R independently represents a divalent alkylene group, at least one or all of the 3 hydroxy groups are secondary hydroxy groups, and the -R-OH is bonded to the trivalent polyoxyalkylene group and has a number average molecular weight of 1200 or less, and contains a polyoxyalkylene triol B2. The urethane adhesive composition according to claim 1.

3. The urethane adhesive composition according to claim 1 or 2, wherein the low molecular weight polyol A contains an alkanediol.

4. The low molecular weight polyol A contains 1,4-butanediol, and the low molecular weight polyol B contains glycerin. The polyisocyanate component contains at least one selected from the group consisting of a urethane prepolymer, diphenylmethane diisocyanate, polymeric MDI, and modified MDI. The urethane adhesive composition according to any one of claims 1 to 3.

5. The amount of the hydroxy groups of the low molecular weight polyol B is 3.0 to 90.0 mol% in the total amount of the hydroxy groups of the low molecular weight polyol A and the low molecular weight polyol B. The urethane adhesive composition according to any one of claims 1 to 4, wherein the amount of the hydroxy groups of the low molecular weight polyol B is 30 to 90 mol% in the total amount of the hydroxy groups of the high molecular weight polyol and the low molecular weight polyol B.

6. The urethane adhesive composition according to any one of claims 1 to 5, wherein the elastic modulus after complete curing is 15 MPa or more.

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