JP2020023602A - Two-pack curable type adhesive - Google Patents

Abstract

To provide a two-pack curable type adhesive which has high adhesive strength, glass transition temperature, and elongation percentage, and achieves both of workability and little hanging during use.SOLUTION: The two-pack curable adhesive comprises a first component and a second component, in which the first component contains an aromatic diamine (A1) having molecular weight of 100 to 300, the second component contains an isocyanate group-terminated urethane prepolymer (B1) having an isocyanate group content of 2 to 18 mass%, the isocyanate group-terminated urethane prepolymer (B1) is obtained by reacting at least one or both of aliphatic diisocyanate (B1a) and alicyclic diisocyanate (B1b), and a polyol (B1c) having an oxyalkylene group.SELECTED DRAWING: None

Description

  The present invention relates to a two-part curable adhesive.

  Two-part curable adhesives utilizing a curing reaction between a component containing a polyisocyanate and a component containing an active hydrogen compound have been used in various fields.

The adhesive is required to firmly adhere members to each other. For example, Japanese Patent Application Publication No. 2011-509316 (Patent Document 1) discloses a two-component curable polyurethane-based adhesive composition having a high adhesive strength. It has been disclosed.

Adhesives may be required to maintain adhesive strength over a wide temperature range. However, the adhesive disclosed in Patent Document 1 has a problem that it is difficult to use the adhesive in a high temperature range because the glass transition temperature is not high.

Further, in the case of a conventional polyurethane-based adhesive composition, when an attempt is made to achieve a high glass transition temperature, the elongation until breakage (hereinafter, also simply referred to as “elongation”) tends to decrease, and a high glass transition It was difficult to achieve both temperature and high elongation. In addition, it was necessary to achieve both workability during use and difficulty in sagging.

2011-509316 gazette

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a two-liquid composition having high adhesive strength, glass transition temperature, and elongation, and having both workability during use and low dripping. It is to provide a curable adhesive.

In order to solve the above problems, a two-part curable adhesive according to an aspect of the present invention has a first component and a second component, and the first component is an aromatic diamine having a molecular weight of 100 to 300 ( A1), wherein the second component contains an isocyanate group-terminated urethane prepolymer (B1) having an isocyanate group content of 2 to 18% by mass, and the isocyanate group-terminated urethane prepolymer (B1) is at least aliphatic. It is obtained by reacting one or both of diisocyanate (B1a) and alicyclic diisocyanate (B1b) with polyol (B1c) having an oxyalkylene group.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive strength, glass transition temperature, and elongation can be provided, and the two-component hardening type adhesive which made workability | operativity at the time of use and dripping difficult can be provided.

  First, the contents of the embodiment of the present invention will be listed and described.

(1) The two-component curable adhesive according to the embodiment of the present invention has a first component and a second component, and the first component contains an aromatic diamine (A1) having a molecular weight of 100 to 300. The second component contains an isocyanate group-terminated urethane prepolymer (B1) having an isocyanate group content of 2 to 18% by mass, and the isocyanate group-terminated urethane prepolymer (B1) contains at least an aliphatic diisocyanate (B1a). And one or both of an alicyclic diisocyanate (B1b) and a polyol having an oxyalkylene group (B1c).

  With such a configuration, it is possible to obtain a two-part curable adhesive having high adhesive strength, glass transition temperature, and elongation after curing, and having both workability during use and resistance to sagging. More specifically, the two-component curable adhesive is one in which the adhesive strength after curing, the glass transition temperature, and the elongation are comprehensively improved. Further, in actual use, the two-component curable adhesive is highly workable to maintain a viscosity that can be applied for a certain period of time after mixing, and is hardly dripped even when applied to a vertical surface or the like. Has properties.

(2) Preferably, the second component further contains an aromatic diisocyanate (B2), and the sum of the aliphatic diisocyanate (B1a) and the alicyclic diisocyanate (B1b), and the aromatic diisocyanate (B2) Has a mass ratio ((B2) / ((B1a) + (B1b))) of 0.1 to 0.5.

  With such a configuration, it is possible to obtain a two-part curable adhesive having higher adhesive strength, glass transition temperature, and elongation after curing, and having both workability during use and resistance to sagging.

  (3) Preferably, the amount of the isocyanate group contained in the second component is 70 to 150 mol% with respect to the active hydrogen group contained in the first component.

  With such a configuration, it is possible to obtain a two-part curable adhesive having higher adhesive strength, glass transition temperature, and elongation after curing, and having both workability during use and resistance to sagging.

  (4) The amount of the amino group contained in the first component is 60 to 100 mol% with respect to the active hydrogen group contained in the first component.

  With such a configuration, it is possible to obtain a two-part curable adhesive having higher adhesive strength, glass transition temperature, and elongation after curing, and having both workability during use and resistance to sagging.

  Hereinafter, embodiments of the present invention will be specifically described.

[Two-component curable adhesive]
The two-component curable adhesive according to the present embodiment includes at least a first component and a second component. Since the two-component curable adhesive is cured by mixing the first component and the second component, it can exhibit the function as an adhesive.

[First component]
The first component in the two-part curable adhesive according to the present embodiment contains an aromatic diamine (A1) having a molecular weight of 100 to 300. The aromatic diamine (A1) is not particularly limited, but is preferably a diamine having a structure in which at least two amino groups are bonded to a toluene structure. Specifically, diethyltoluenediamine, dimethylthiotoluenediamine, diaminotoluene, trimethylphenylenediamine and the like are preferable. These may be used alone or in combination of two or more.

As the aromatic diamine (A1), the viewpoint of improving the adhesive strength (adhesive strength), glass transition temperature, and elongation of a two-part curable adhesive, and achieving both workability during use and resistance to sagging. Thus, diethyltoluenediamine and dimethylthiotoluenediamine are preferred.

  The first component may include, for example, a polyol. Examples of the polyol include, but are not particularly limited to, polyhydric alcohol, polyether polyol, polyester polyol, polycarbonate polyol, polyolefin polyol, polyacryl polyol, polyacetal polyol, polybutadiene polyol, polysiloxane polyol, and fluorine polyol. As for the said polyol, 100-5000 are preferable and 200-3000 are more preferable.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, butanediol, propylene glycol, hexanediol, 3-methyl-1,5-pentanediol, bisphenol A, bisphenol B, bisphenol S, hydrogenated bisphenol A, Bromobisphenol A, 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, hydroquinone dihydroxyethyl ether, trimethylolpropane, glycerin, pentaerythritol and the like can be mentioned.

  Examples of the polyether polyol include an oxyalkylene derivative of the polyhydric alcohol, polytetramethylene glycol, and polythioether polyol. Specifically, polyethylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene bisphenol A, polyoxypropylene bisphenol A, polyoxyethylene polyoxypropylene bisphenol A, polyoxyethylene glyceryl ether, polyoxypropylene glyceryl Ether, polyoxyethylene polyoxypropylene glyceryl ether, polyoxyethylene trimethylolpropane, polyoxypropylene trimethylolpropane, polyoxyethylene polyoxypropylene trimethylolpropane, and the like.

  Examples of the polyester polyol include an esterified product of a hydroxyl group-containing compound such as a polyhydric alcohol and a polyether polyol, and a carboxylic acid derivative such as a polycarboxylic acid, a polycarboxylic anhydride and a polycarboxylic ester. Can be Specifically, at least one diol selected from ethylene glycol, butanediol, hexanediol, methylpentanol, neopentyl glycol and 1,4-cyclohexanedimethanol, adipic acid, sebacic acid, And esterified products with at least one dicarboxylic acid selected from isophthalic acid and terephthalic acid. As the polyester polyol, castor oil polyol, polycaprolactone polyol and the like can also be used.

  Examples of the polycarbonate polyol include those comprising a carbonate derivative such as dimethyl carbonate and the above-mentioned polyhydric alcohol. Specifically, a polycarbonate polyol comprising dimethyl carbonate and at least one selected from ethylene glycol, butanediol, hexanediol, 3-methyl-1,5-pentanediol and 1,4-cyclohexanediol Is mentioned.

  Examples of the polyolefin polyol include polybutadiene polyol, polyisoprene polyol, and hydrogenated products thereof.

Further, the first component may include, for example, a filler. Examples of the filler include, but are not particularly limited to, calcium carbonate, talc, silica, and mica. By adding a filler, the viscosity during operation can be further adjusted.

The first component may include a water-absorbing material from the viewpoint of increasing the tensile strength (tensile strength) of the cured adhesive. Examples of the water-absorbing material include porous powder, water-absorbing alumina, and calcium oxide. These may be used alone or in combination of two or more. As the water absorbing material, porous powder is preferable, and zeolite is more preferable.

The water-absorbing material is not particularly limited, but is preferably used in an amount of 0.5 to 5 parts by mass, more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the first component.

The amount of amino groups contained in the first component relative to the active hydrogen groups contained in the first component, that is, the amount of amino groups in the active hydrogen groups contained in the first component is not particularly limited. It is preferably at least 70 mol%, more preferably at least 70 mol%, even more preferably at least 80 mol%, even more preferably at least 90 mol%.

[Second component]
The second component in the two-part curable adhesive according to the present embodiment contains an isocyanate group-terminated urethane prepolymer (B1) having an isocyanate group content of 2 to 18% by mass. The isocyanate group content of the isocyanate group-terminated urethane prepolymer (B1) further improves the adhesive strength, glass transition temperature, and elongation of the two-part curable adhesive, and improves workability and sagging during use. From the viewpoint of compatibility, the content is preferably 3 to 16% by mass, more preferably 4 to 14% by mass, and still more preferably 5 to 12% by mass.

  The isocyanate group-terminated urethane prepolymer (B1) is obtained by reacting at least one or both of an aliphatic diisocyanate (B1a) and an alicyclic diisocyanate (B1b) with a polyol (B1c) having an oxyalkylene group. It is a thing.

Specifically, the isocyanate group-terminated urethane prepolymer (B1) is obtained, for example, by mixing one or both of an aliphatic diisocyanate (B1a) and an alicyclic diisocyanate (B1b) with a polyol (B1c) having an oxyalkylene group. It is obtained by reacting at a ratio such that the number of isocyanate groups is excessive relative to the number of active hydrogen groups. The active hydrogen group is a functional group that reacts with an isocyanate group, and includes a hydroxyl group and an amino group.

When both the aliphatic diisocyanate (B1a) and the alicyclic diisocyanate (B1b) are used for producing the isocyanate group-terminated urethane prepolymer (B1), the aliphatic diisocyanate (B1a) and the alicyclic diisocyanate (B1b) are used. The mass ratio ((B1b) / ((B1a) + (B1b))) of the total amount to the alicyclic diisocyanate (B1b) is preferably 0.5 or more, more preferably 0.7 or more, and 0.8 or more. The above is more preferable, 0.9 or more is more preferable, and 0.95 or more is further preferable.

  Although it does not specifically limit as an aliphatic diisocyanate (B1a), Butane diisocyanate, pentane diisocyanate, hexamethylene diisocyanate (henceforth "HDI"), trimethylhexamethylene diisocyanate, lysine diisocyanate, etc. can be mentioned. Any of these may be used alone or in combination of two or more.

As the aliphatic diisocyanate (B1a), HDI is preferred from the viewpoints of improving the adhesive strength, glass transition temperature, and elongation of the two-part curable adhesive, and achieving both workability during use and resistance to sagging. .

  Although it does not specifically limit as an alicyclic diisocyanate (B1b), isophorone diisocyanate (henceforth "IPDI"), hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate (henceforth "hydrogenated MDI"). And 1,4-cyclohexane diisocyanate. Any of these may be used alone or in combination of two or more.

As the alicyclic diisocyanate (B1b), IPDI, IPDI, Hydrogenated MDI is preferred.

Examples of the polyol (B1c) having an oxyalkylene group include, but are not particularly limited to, water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, ethylenediamine, and methylgluline. Those obtained by polymerizing and adding an alkylene oxide (hereinafter, also referred to as “AO”) to an initiator such as kodite, aromatic diamine, sorbitol, sucrose, phosphoric acid and the like can be used. Moreover, you may use these in combination of 2 or more types. As AO, ethylene oxide, propylene oxide and butylene oxide are preferred.

  The molecular weight of the polyol having an oxyalkylene group (B1c) is preferably from 400 to 8000, more preferably from 500 to 7000, more preferably from 500 to 6000, and more preferably from 1000, from the viewpoint of increasing tensile strength, glass transition temperature, and adhesive strength. 6000 is more preferable, 1200 to 6000 is more preferable, and 1400 to 6000 is still more preferable.

In the present disclosure, “molecular weight” represents a number average molecular weight of a compound having a molecular weight distribution such as polypropylene glycol.

  The second component may contain an aromatic diisocyanate (B2). This makes it possible to suppress the dripping of the two-component curable adhesive until the curing of the two-component curable adhesive is completed, for example. The property showing such ease of sagging is also called sag. Suitable sag depends on the application of the two-part curable adhesive.

Although it does not specifically limit as an aromatic diisocyanate (B2), For example, dialkyl diphenylmethane diisocyanate, tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (henceforth, "Monomeric MDI"), polymethylene polyphenyl polyisocyanate (hereinafter also referred to as "polymeric MDI"), 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, 1,3-phenylene diisocyanate And 1,4-phenylene diisocyanate.

As the aromatic diisocyanate (B2), a modified polyisocyanate can be used. As the modified polyisocyanate, a biuret modified product, an adduct modified product, a carbodiimide modified product, a bifunctional modified product, or the like can be used. These may be used alone or in combination of two or more.

As the aromatic diisocyanate (B2), monomeric MDI is used from the viewpoint of improving the adhesive strength, glass transition temperature, and elongation of the two-part curable adhesive, and achieving both workability during use and resistance to dripping. , Polymeric MDI and carbodiimide-modified monomeric MDI are preferred.

The mass ratio ((B2) / ((B1a) + (B1b))) of the total of the aliphatic diisocyanate (B1a) and the alicyclic diisocyanate (B1b) to the aromatic diisocyanate (B2) is, for example, two-pack curing. From the viewpoints of improving the adhesive strength, glass transition temperature, and elongation of the mold adhesive, and achieving both workability during use and resistance to sagging, it is preferably 0.1 to 0.5. It is more preferably 1 to 0.45, more preferably 0.1 to 0.4, and even more preferably 0.1 to 0.35.

The amount of the isocyanate group contained in the second component with respect to the active hydrogen group contained in the first component is, for example, to improve the adhesive strength, glass transition temperature, and elongation of a two-part curable adhesive, and From the viewpoint of achieving both workability at the time and difficulty in sagging, it is preferably 70 to 150 mol%, more preferably 80 to 130 mol%, further preferably 90 to 120 mol%.

  The two-part curable adhesive may contain, for example, additives generally used in polyurethane resin compositions and the like, such as a plasticizer, a pigment, an antifoaming agent, and a curing catalyst.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples. In the following Examples and Comparative Examples, “parts” or “%” is based on mass unless otherwise specified.

  Table 1 shows the types and amounts of raw materials to be blended to adjust each of the first component and the second component, various ratios of the first component and the second component, and the results of evaluations described later. .

  In Table 1, the "proportion etc." is the isocyanate group-terminated urethane prepolymer (B1) in terms of the isocyanate group content (% by mass), the total of the aliphatic diisocyanate (B1a) and the alicyclic diisocyanate (B1b), and the aromatic diisocyanate. Mass ratio to (B2) ((B2) / ((B1a) + (B1b))), the amount of the isocyanate groups contained in the second component relative to the active hydrogen groups contained in the first component (mol%), and Shows the amount (mol%) of the amino group contained in the first component with respect to the active hydrogen group contained in the first component.

Hereinafter, details of each raw material described in Table 1 are shown.
(Raw material of the first component)
[Aromatic diamine having a molecular weight of 100 to 300 (A1)]
・ (A1-1)
Diethyltoluenediamine (molecular weight 178)
Albemarle Japan Etacure 100
・ (A1-2)
Dimethylthiotoluenediamine (molecular weight 214)
Albemarle Japan Ecacure 300
・ Comparative material (AC-1)
Polytetramethylene oxide-di-P-aminobenzoate (molecular weight 488)
Erasmer 250P manufactured by Kumiai Chemical Industries
・ Comparative material (AC-2)
Polytetramethylene oxide-di-P-aminobenzoate (molecular weight 1238)
Erasmer 1000P manufactured by Kumiai Chemical Industries

[Polyol]
・ (C-1)
Polyether polyol (molecular weight 1500, trifunctional)
Exenol 903 manufactured by Asahi Glass Co., Ltd.

[Filler]
・ (C-2)
Calcium carbonate
Calcium carbonate NS100 manufactured by Nitto Powder Chemical Co., Ltd.
・ (C-3)
talc
Soapstone A manufactured by Imeris Specialties Japan

[Water absorption material]
・ (C-4)
Zeolite
Molecular sieve 3AB manufactured by Union Showa

(Raw material of the second component)
[Aliphatic diisocyanate (B1a)]
・ (B1a-1)
HDI
Asahi Kasei Duranate 50MS

[Alicyclic diisocyanate (B1b)]
・ (B1b-1)
IPDI
VESTANAT IPDI manufactured by Degussa Japan
・ (B1b-2)
Hydrogenated MDI
VESTANAT H12MDI manufactured by Degussa Japan

[Polyol having oxyalkylene group (B1c)]
・ (B1c-1)
Polyether polyol (molecular weight 3000, trifunctional)
Exenol 230 manufactured by Asahi Glass Co., Ltd.
・ (B1c-2)
Polyether polyol (molecular weight 5000, trifunctional)
Exenol 827 manufactured by Asahi Glass Co., Ltd.
・ (B1c-3)
Polyether polyol (molecular weight 1500, trifunctional)
Exenol 903 manufactured by Asahi Glass Co., Ltd.
・ (B1c-4)
Polyether polyol (molecular weight 1000, bifunctional)
Exenol 1020 manufactured by Asahi Glass Co., Ltd.

[Aromatic diisocyanate (B2)]
・ (B2-1)
Carbodiimide-modified MDI
BASF INOAC Polyurethane Luplanate MM-103
・ (B2-2)
Polymeric MDI
Nippon Polyurethane Industry Millionate MR-100

[catalyst]
・ (D-1)
Dioctyltin dilaurate
Neostan u-810, manufactured by Nitto Kasei Corporation

(Adjustment of the first component and the second component)
According to the compounding amounts (parts by mass) shown in Table 1, the first and second components of Examples 1 to 14 and Comparative Examples 1 to 4 were prepared. For the second component, specifically, in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, in the presence of a catalyst, aliphatic diisocyanate (B1a) and alicyclic diisocyanate An isocyanate group-terminated urethane prepolymer (B1) was obtained by reacting at least one of (B1b) with a polyol (B1c) having an oxyalkylene group at 90 ° C. for 3 hours. And the 2nd component which mix | blended the obtained isocyanate group terminal urethane prepolymer (B1) was adjusted.

(Evaluation)
Hereinafter, the evaluation method will be described. Table 1 also shows the evaluation results.

(1) Mixed viscosity (Pa · s)
After mixing the first component and the second component adjusted to 25 ° C. for 1 minute, the mixture was allowed to stand still at 25 ° C., and the viscosity was measured 5 minutes after the start of mixing. The viscosity was measured using an RVT type viscometer (manufactured by Brookfield) according to JIS K7117-1: 1999. In addition, it is preferable that the mixed viscosity is suppressed to 4000 (Pa · s) or less from the viewpoint of preventing deterioration of workability.

(2) The first component and the second component adjusted to a sag of 25 ° C. were mixed for 1 minute, and then allowed to stand in an environment of 25 ° C., and 5 minutes after the mixing, 100 mm in length and 100 mm in width on a glass plate were observed. The mixture was applied to the region so that the film thickness was 4 mm. The glass plate was placed upright and allowed to stand for 30 minutes in a 25 ° C. environment, and the dripping property of the mixture was determined.
A: not dripping B: dripping, but the dripping length is less than 1 cm C: dripping not less than 1 cm

(3) Tack free time (min)
The first component and the second component adjusted to 25 ° C. were mixed for 1 minute, and the time from the start of mixing until the surface of the mixture was no longer sticky, that is, the tack free time was measured. Whether or not the tack was lost was determined by finger touch.

(4) Tensile strength (N / mm ² ) and elongation at break (%)
The first component and the second component adjusted to 25 ° C. were mixed for 1 minute, and 2 minutes after the mixing, the mixture was applied to a glass surface to a thickness of 2 mm. This was allowed to stand for 7 days in an environment of 23 ° C. to be cured, and then peeled from the glass surface to obtain a resin sheet. From the obtained sheet, a test piece of 5 mm × 4 cm was cut out, and the tensile strength (N / mm ² ) was measured with a digital universal testing machine (Instron 5581) manufactured by Instron Japan according to JIS A6021-2011: 2011. The elongation at break (%) was measured. At that time, the test speed was 20 mm / min.

(5) Glass transition temperature (° C)
The first component and the second component adjusted to 25 ° C. were mixed for 1 minute, and 2 minutes after the mixing, the mixture was applied to a glass surface so as to have a thickness of 2 mm. This was allowed to stand for 7 days in an environment of 23 ° C. to be cured, and then peeled from the glass surface to obtain a resin sheet. A test piece of 5 mm × 2 cm was cut out from the obtained resin sheet, and the glass transition temperature was measured with Rheogel E-4000 manufactured by UBM in accordance with JIS K7244-4: 1999.

(6) Adhesive strength (MPa)
The first component and the second component adjusted to 25 ° C. are mixed for 1 minute, and after 2 minutes, the mixture is mixed with an electrodeposition coated steel sheet (ED steel sheet) having a length of 25 mm × width 100 mm × thickness 1.6 mm. JIS K 6850: 1999. Specifically, the adhesive test piece applies an adhesive to the surface of two ED steel plates, and bonds the ED steel plates together so that the overlap area is 25 mm in length and 12.5 mm in width. For 7 days to cure. At this time, the thickness of the adhesive was adjusted to 1 mm. Then, using a digital universal tester (Instron 5581) manufactured by Instron Japan, the lap shear strength (MPa) of the adhesive test piece was measured as the adhesive strength of the adhesive. At that time, the test speed was 5 mm / min.

Referring to Table 1, as compared with Comparative Examples 1 to 4, Examples 1 to 14 have an overall improved adhesion strength, glass transition temperature, and elongation after curing, and also show actual use. While suppressing the mixing viscosity (that is, the viscosity of the liquid mixture) to the extent that the workability is not deteriorated, the sagging property has been highly evaluated. Also, comparing Example 4 with Examples 1 and 5, when obtaining an isocyanate group-terminated urethane prepolymer (B1), the use of alicyclic diisocyanate (B1b), It can be seen that the tensile strength, glass transition temperature, and adhesive strength are excellent. Further, comparing Example 9 with Examples 6 to 8, when the molecular weight of the polyol (B1c) having an oxyalkylene group is in the range of 1200 to 6000, the tensile strength, the glass transition temperature, and the adhesive strength It is clear that the tack free time is short and the tack free time is short. In Comparative Example 4, the viscosity was rapidly increased after mixing, and the mixed viscosity could not be measured.

Claims (4)

A two-part curable adhesive having a first component and a second component,
The first component contains an aromatic diamine (A1) having a molecular weight of 100 to 300,
The second component contains an isocyanate group-terminated urethane prepolymer (B1) having an isocyanate group content of 2 to 18% by mass,
The isocyanate group-terminated urethane prepolymer (B1) is obtained by reacting at least one or both of an aliphatic diisocyanate (B1a) and an alicyclic diisocyanate (B1b) with a polyol (B1c) having an oxyalkylene group. A two-part curable adhesive. The second component further contains an aromatic diisocyanate (B2),
The mass ratio of the sum of the aliphatic diisocyanate (B1a) and the alicyclic diisocyanate (B1b) to the aromatic diisocyanate (B2) ((B2) / ((B1a) + (B1b))) is 0.1 to 0.1. The two-part curable adhesive according to claim 1, which has a value of 0.5.   3. The two-part curable adhesive according to claim 1, wherein an amount of the isocyanate group contained in the second component is 70 to 150 mol% based on an active hydrogen group contained in the first component. 4. The two-part curing method according to any one of claims 1 to 3, wherein the amount of the amino group contained in the first component is 60 to 100 mol% with respect to the active hydrogen group contained in the first component. Mold adhesive.