JP2013072016A - One-component urethane-based adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one-component urethane-based adhesive for vehicle roof portions, which has high strength, flexible physical properties, heat resistance and low-temperature fast-curing properties.SOLUTION: The one-component urethane-based adhesive contains two kinds of urethane prepolymers, an amine-based latent curing agent and a curing catalyst.

Description

  The present invention relates to a one-component urethane-based adhesive, and more particularly, to a one-component urethane-based adhesive having high strength and flexible physical properties and heat resistance, and having a low-temperature fast-curing property.

  In recent years, semi-structured parts such as metal roofs and hatchbacks have been replaced with resin products in order to reduce the weight of automobiles. In order to assemble these resin roof parts to a steel plate vehicle, an adhesive method using an adhesive is usually used. Examples of the adhesive used in such a construction method include a two-component curable adhesive. However, the two-component curable adhesive needs to be mixed and discharged at a predetermined ratio between the main agent and the curing agent, so that complicated equipment is required. is necessary. In addition, since the thermosetting adhesive needs to be cured by heating at a high temperature, there is a problem that it is not suitable for bonding resin products.

  Thus, a one-component thermosetting adhesive has been proposed (Patent Document 1), but it took time until handling strength was developed, and sufficient strength could not be obtained.

JP 05-78447 A

  An object of the present invention is to provide a one-component urethane-based adhesive for automobile roof parts, which has high strength and flexible physical properties and heat resistance, and has low-temperature fast curing properties.

The present inventors have found that the above problem can be solved by a one-component urethane adhesive containing two types of urethane prepolymers, an amine latent curing agent and a curing catalyst.
That is, the following preferred embodiments are included in the present invention.
[1] (A) (1) a polyol containing a diol having a number average molecular weight of 300 to 800, and a urethane prepolymer obtained by reacting (2) an aliphatic polyisocyanate,
(B) (1) a polyol containing a diol and a tri- or higher functional polyol, and (2) a urethane prepolymer obtained by reacting an aromatic polyisocyanate,
A one-component urethane-based adhesive used for a roof part of an automobile, comprising (C) an amine-based latent curing agent and (D) a curing catalyst.
[2] Polyol (A) (1) contains 7 to 10 parts by weight of tetraol and 30 to 50 parts by weight of diol having a number average molecular weight of 300 to 800, based on 100 parts by weight of triol. ] The one-component type urethane-type adhesive agent of description.
[3] The NCO / OH equivalent ratio of the polyol (A) (1) and the aliphatic polyisocyanate (A) (2) is 1.9 to 2.1, 1 according to [1] or [2] Component type urethane adhesive.
[4] The NCO / OH equivalent ratio of the polyol (B) (1) and the aliphatic polyisocyanate (B) (2) is 1.9 to 2.1, and any one of [1] to [3] The one-component urethane adhesive described in 1.
[5] The one-component urethane adhesive according to any one of [1] to [4], wherein the weight ratio of the urethane prepolymer (A) and the urethane prepolymer (B) is 35:65 to 65:35. Agent.
[6] The amine latent curing agent (C) is a fine powder coating amine obtained by coating an amine that is solid at 50 ° C. with an inorganic powder. Component type urethane adhesive.
[7] The one-component urethane adhesive according to any one of [1] to [6], wherein the curing catalyst (D) is a tin-based catalyst.
[8] The one-component urethane adhesive according to any one of [1] to [7], wherein the aromatic polyisocyanate is TDI.

  The one-component urethane-based adhesive of the present invention has high strength and flexible physical properties and heat resistance, and has a low-temperature fast-curing property. Therefore, it can be used for automobile resin roofs such as roofs and hatchbacks. It can be suitably used for bonding to a vehicle.

The present invention
(A) (1) a polyol containing tetraol, triol and a diol having a number average molecular weight of 300 to 800, and (2) a urethane prepolymer obtained by reacting an aliphatic polyisocyanate,
(B) (1) a polyol containing a diol and a tri- or higher functional polyol, and (2) a urethane prepolymer obtained by reacting an aromatic polyisocyanate,
A (C) amine-based latent curing agent and (D) a one-component urethane-based adhesive used for an automobile roof portion, which includes a curing catalyst.

The polyol (A) (1) used for the urethane prepolymer (A) comprises tetraol, triol, and a diol having a number average molecular weight of 300 to 800.
When the polyol (A) (1) contains tetraol, triol and a diol having a number average molecular weight of 300 to 800, a cured product having a desired strength can be obtained.

  Polyols contained in the polyol (A) (1) include polyhydric alcohols such as water, ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose and the like, propylene Polyether polyols obtained by addition polymerization of oxide or propylene oxide and alkylene oxide such as ethylene oxide; ethylene glycol, propylene glycol and oligoglycols thereof; butylene glycol, hexylene glycol, polytetramethylene ether glycols; polycaprolactone polyol Polyester polyols such as polyethylene adipate; polybutadiene polyols; high hydroxyl groups such as castor oil Fatty acid esters; polyether polyols or polymeric polyols grafted vinyl monomer to the polyester polyols and the like. In the present invention, a polyether polyol such as polyoxypropylene diol, polyoxypropylene ethylene diol, polyoxypropylene triol, polyoxypropylene ethylene triol, polyoxypropylene tetraol, polyoxypropylene ethylene tetraol, etc. has a high cured product. It is suitable because it has strong and flexible physical properties.

The tetraol used for the polyol (A) (1) preferably has a number average molecular weight of 300 or more, more preferably 400 or more. Moreover, the tetraol used for polyol (A) (1) has a number average molecular weight of 800 or less, more preferably 700 or less. When the number average molecular weight is less than 300, a desired high-strength cured product cannot be obtained, and when it exceeds 800, a desired high-strength cured product cannot be obtained.
The number average molecular weight was measured by polystyrene conversion using GPC in which three KF806L columns were connected.

  The triol used for the polyol (A) (1) preferably has a number average molecular weight of 3000 or more, more preferably 5000 or more. Moreover, the triol used for polyol (A) (1) has a number average molecular weight of 10000 or less, more preferably 7000 or less. When the number average molecular weight is less than 3000, a desired highly stretched cured product cannot be obtained, and when it exceeds 10,000, a desired high strength cured product cannot be obtained.

  The diol used in the polyol (A) (1) has a number average molecular weight of 300 or more, preferably 400 or more. The diol has a number average molecular weight of 800 or less, preferably 700 or less. When the number average molecular weight is less than 300, a highly stretched cured product cannot be obtained, and when the number average molecular weight exceeds 800, a high strength cured product cannot be obtained.

  The polyol (A) (1) is preferably 7 to 10 parts by weight of tetraol and 30 to 50 parts by weight of a diol having a number average molecular weight of 300 to 800, more preferably 35, based on 100 parts by weight of triol. -45 parts by weight of a diol having a number average molecular weight of 300-800. When the polyol (A) (1) contains triol, tetraol and a diol having a number average molecular weight of 300 to 800 in an amount within the above range, it is advantageous in terms of strength of the cured product.

An aliphatic polyisocyanate (A) (2) is used to produce the urethane prepolymer (A). When an aliphatic polyisocyanate is used, a cured product having desired heat resistance can be obtained.
The aliphatic polyisocyanate (A) (2) used in the urethane prepolymer (A) is not particularly limited, but is isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), lysine diisocyanate, 2,2,4- and 2,4,4-trimethylhexamethylene diisocyanate, these isocyanurates, carbodiimides, burettes, and the like are mentioned. Among them, IPDI is preferable from the viewpoint of heat resistance.
As an example of the commercial item of the said aliphatic polyisocyanate, the Bayer Desmodur I (IPDI) etc. are mentioned, for example.
In the one-component urethane adhesive according to the present invention, the aliphatic polyisocyanate may be used alone or in combination of two or more.

  The urethane prepolymer (A) comprises a polyol (A) (1) and an aliphatic polyisocyanate (A) (2) having an NCO / OH equivalent ratio of preferably 1.9 to 2.1. Preferably, it is obtained by reacting to be 1.95 to 2.05. When the equivalent ratio of NCO / OH is less than 1.9, the storage stability is lowered and the viscosity tends to increase or gel. Moreover, when it exceeds 2.1, there exists a tendency for a high intensity | strength hardened | cured material not to be obtained.

  The above reaction may be carried out by using an appropriate reaction solvent such as ethyl acetate, toluene, xylene and the like, and a reaction catalyst such as an organotin catalyst such as dibutyltin dilaurate, a bismuth catalyst such as bismuth octylate, 1,4- In the presence of a tertiary amine catalyst such as diaza [2.2.2] bicyclooctane or the like, the reaction can usually be performed at room temperature to 60 to 90 ° C. for 1 to 7 hours. The resulting urethane prepolymer can usually have an NCO content of 0.5-5% (% by weight, hereinafter the same) and a viscosity of 5000-100000 cps / 20 ° C.

The one-component urethane adhesive of the present invention comprises a urethane prepolymer (B) in addition to the urethane prepolymer (A).
The polyol (B) (1) used for the urethane prepolymer (B) comprises a diol and a trifunctional or higher functional polyol.
When the polyol (B) (1) contains a diol and a trifunctional or higher functional polyol, a cured product having a desired strength can be obtained.

  Polyols contained in the polyol (B) (1) include polyhydric alcohols such as water, ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose and the like, propylene Polyether polyols obtained by addition polymerization of oxide or propylene oxide and alkylene oxide such as ethylene oxide; ethylene glycol, propylene glycol and oligoglycols thereof; butylene glycol, hexylene glycol, polytetramethylene ether glycols; polycaprolactone polyol Polyester polyols such as polyethylene adipate; polybutadiene polyols; high hydroxyl groups such as castor oil Fatty acid esters; polyether polyols or polymeric polyols grafted vinyl monomer to the polyester polyols and the like. In the present invention, a polyether polyol such as polyoxypropylene diol, polyoxypropylene ethylene diol, polyoxypropylene triol, polyoxypropylene ethylene triol, polyoxypropylene tetraol, polyoxypropylene ethylene tetraol, etc. has a high cured product. It is preferable because it has strong and flexible physical properties.

  The diol used in the polyol (B) (1) preferably has a number average molecular weight of 800 or more, more preferably 1000 or more. The diol used for the polyol (B) (1) preferably has a number average molecular weight of 4000 or less, more preferably 3000 or less. When the number average molecular weight is less than 800, a desired high-strength cured product cannot be obtained, and when it exceeds 4000, a desired high-strength cured product cannot be obtained.

  The trifunctional or higher functional polyol used in the polyol (B) (1) preferably has a number average molecular weight of 3000 or higher, more preferably 4000 or higher. Moreover, the trifunctional or higher functional polyol used in the polyol (B) (1) preferably has a number average molecular weight of 8000 or less, more preferably 7000 or less. If the number average molecular weight is less than 3000, a desired highly stretched cured product cannot be obtained, and if it exceeds 8000, a desired high strength cured product cannot be obtained.

In the present invention, the aromatic polyisocyanate (B) (2) is used to produce the urethane prepolymer (B). When an aromatic polyisocyanate is used, a cured product having a desired storage stability can be obtained.
Although it does not specifically limit as aromatic polyisocyanate (B) (2) used for the said urethane prepolymer (B), Tolylene diisocyanate (TDI), 4,4'- diphenylmethane diisocyanate, xylylene diisocyanate, tolidine diisocyanate, etc. Among them, TDI is preferable from the viewpoint of storage stability and workability (viscosity).
As an example of the commercial item of the said aromatic polyisocyanate, the Mitsui Chemicals Cosmonate T-80 etc. are mentioned, for example.
In the one-component urethane adhesive according to the present invention, the aromatic polyisocyanate may be used alone or in combination of two or more.

  In the urethane prepolymer (B), the polyol (B) (1) and the aromatic polyisocyanate (B) (2) have an NCO / OH equivalent ratio of preferably 1.9 to 2.1. Preferably, it is obtained by reacting to be 1.95 to 2.05. If the equivalent ratio of NCO / OH is less than 1.9 or exceeds 2.1, a high strength cured product tends to be not obtained.

  The above reaction may be carried out by using an appropriate reaction solvent such as ethyl acetate, toluene, xylene and the like, and a reaction catalyst such as an organotin catalyst such as dibutyltin dilaurate, a bismuth catalyst such as bismuth octylate, 1,4- In the presence of a tertiary amine catalyst such as diaza [2.2.2] bicyclooctane or the like, the reaction can usually be performed at room temperature to 60 to 90 ° C. for 1 to 7 hours. The resulting urethane prepolymer can usually have an NCO content of 0.5-5% (% by weight, hereinafter the same) and a viscosity of 5000-100000 cps / 20 ° C.

  The one-component urethane adhesive according to the present invention contains the urethane prepolymers (A) and (B) in a weight ratio of preferably 35:65 to 65:35, more preferably 40:60 to 60:40. It becomes. When the urethane prepolymers (A) and (B) are contained in a weight ratio within the above range, it is advantageous from the viewpoint of physical properties and storage stability of the cured product.

  The one-component urethane adhesive of the present invention comprises an amine-based latent curing agent (C) in addition to the urethane prepolymers (A) and (B).

As the amine-based latent curing agent (C) in the present invention, any solid amine belonging to an aromatic or aliphatic melting point of 50 ° C. or higher can be used.
Examples of the solid amine include 4,4′-diaminodiphenylmethane, 2,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 2,2′-diaminobiphenyl, and 2,4. '-Diaminobiphenyl, 3,3'-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-phenylenediamine, 2,3-tolylenediamine, 2,4-triene Aromatics such as range amine, 2,5-tolylenediamine, 2,6-tolylenediamine, 3,4-tolylenediamine, 1,12-dodecanediamine, 1,10-decanediamine, 1,8-octane Aliphatics such as diamine, 1,14-tetradecanediamine, 1,16-hexadecanediamine, etc. One or a mixture of two or more of these may be used.

  The solid amine is adjusted to a center particle size of 20 μm or less, preferably 3 to 15 μm. When the center particle diameter exceeds 20 μm, the heat-cured polyurethane becomes incomplete reaction curing, and the desired physical properties tend not to be obtained.

  As the amine-based latent curing agent (C) used in the present invention, the above-mentioned solid amine is pulverized into a predetermined central particle size range, and at the same time, a fine powder is added thereto so that the fine powder has a predetermined central particle size range. A fine powder-coated amine produced by a shear friction mixing method in which fine powder is fixed to the surface of a solid amine, or a high-speed impact mixing stirrer or compression with fine powder A fine powder coating amine produced by using a shearing type mixing stirrer is preferably used. The latter method, particularly a fine powder coated amine produced using a high-speed impact mixing stirrer is particularly preferred.

The fine powder can be used arbitrarily from inorganic or organic, for example, titanium oxide, calcium carbonate, clay, silica, zirconia, carbon, alumina, talc, etc. Examples thereof include vinyl chloride, polyacrylic resin, polystyrene, and polyethylene, and one or a mixture of two or more thereof is used. The amount of the fine powder used is selected so that the weight ratio of the solid amine to the fine powder is 1 / 0.001 to 0.5, preferably 1 / 0.002 to 0.4. When the ratio of the fine powder is less than 0.001, the effect of storage stability is not recognized, and when it exceeds 0.5, the storage stability is not further improved.
By mixing and pulverizing the solid amine and fine powder in this way, static electricity is generated and the fine powder adheres to the surface of the solid amine, or the mechanical force of the mixing stirrer generates friction, impact, compression shear, etc. It is predicted that the fine powder will stick due to the local melting and sticking phenomenon of the solid amine due to the heat generated by the solid amine, or it will be physically thrown or buried firmly on the surface of the solid amine, or even chemically activated and stuck. (That is, the active amino group (NH ₂ ) on the surface of the solid amine is covered with the fine powder). It is important that the center particle size of the fixed fine powder is set to 2 μm or less, preferably 1 μm or less. If it exceeds 2 μm, the fine particle does not adhere to the surface of the solid amine.

Such fine powder coating amine acts as a curing agent for the isocyanate components (A) (2) and (B) (2), but is further reacted with a liquid isocyanate compound (usually at a temperature below the melting point) The remaining active amino group may be inactivated. Examples of the liquid isocyanate compound include crude MDI, p-toluenesulfonyl isocyanate, isophorone diisocyanate, TDI, and n-octadecyl isocyanate. The proportion of the liquid isocyanate compound is usually equivalent ratio of NH ₂ to NCO solid amine may be selected to be 1 / 0.01 to 0.5. By the inactivation treatment with the liquid isocyanate compound, the storage stability is further improved as compared with the case of only the coating treatment with the fine powder. In addition, when the NCO is less than 0.01 in the equivalent ratio, a desired improvement effect of storage stability cannot be obtained, and when it exceeds 0.5, further improvement in storage stability tends not to be obtained. is there.

Thus, the fine powder coating amine obtained by the coating treatment with the fine powder and, if necessary, the inactivation treatment with the liquid isocyanate compound is activated at the curing temperature (usually 60 to 100 ° C.) and is present after the heat activation. NH ₂ to participate in the curing reaction of the isocyanate components (A) (2) and (B) (2) with NCO. Thus, the isocyanate component (A) (2) and (B) (2) and the mixing ratio of the amine-based latent curing agent (C) is usually, NH ₂ and the equivalent ratio of NCO after heating activity 1/0. What is necessary is just to select so that it may become 5-2.0.

  The one-component urethane adhesive of the present invention comprises a curing catalyst (D) in addition to the urethane prepolymers (A) and (B) and the amine latent curing agent (C).

  Examples of the curing catalyst include DBU [1,8-diazabicyclo (5.4.0) undecene-7], DBU phenol salts, DBU octylates, DBU formates and the like; monoamines (such as triethylamine), diamines ( N, N, N ′, N′-tetramethylethylenediamine etc.), triamine (tetramethylguanidine etc.), cyclic amine (triethylenediamine etc.), alcohol amine (dimethylaminomethanol etc.), ether amine [bis (2-dimethylamino) Ethyl) ethers and the like; Sn-based (dibutyltin dilaurate, tin octylate, etc.), Pb-based (lead octylate, etc.), Zn-based (zinc octylate, etc.) organic carboxylic acid metal salts; Examples include imidazole series such as methylimidazole and 1,2-dimethylimidazole. These may be used alone or in combination of two or more. Sn-based organic carboxylic acid metal salts such as dibutyltin dilaurate, dibutyltin diacetylacetonate, and tin octylate are preferred from the viewpoint of promoting the reaction.

  In the one-component urethane adhesive of the present invention, the curing catalyst (D) is preferably 0.001 to 0.1 parts by weight, more preferably 100 parts by weight of the one-component urethane adhesive of the present invention. Comprises 0.005 to 0.05 parts by weight.

  The one-component urethane-based adhesive of the present invention may further contain, as necessary, ordinary additives such as solvents (for example, aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons as solvents having a small polarity). , Halogenated hydrocarbons, ethers, esters, ketones, etc., particularly preferred are aliphatic hydrocarbon solvents, plasticizers (eg dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, diisooctyl phthalate) Diisodecyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, trioctyl phosphate, epoxy plasticizer, toluene-sulfonamide, chloroparaffin, adipic acid ester, castor oil, etc.), thixotropic agent, ultraviolet absorber, anti-aging agent, An appropriate amount of a dye / pigment, an adhesive, a dehydrating agent, and the like may be blended.

  The one-component urethane-based adhesive of the present invention is composed of the above-described components, and can be produced by mixing these components using, for example, a high-speed stirring mixer, a pearl mill, or the like.

  The one-component urethane adhesive of the present invention is heated at a relatively low temperature of 60 ° C. to 120 ° C., preferably 80 ° C. to 100 ° C., within 10 minutes to 60 minutes, preferably within 15 minutes to 30 minutes. It can be cured in a short time.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited thereto.

Production of prepolymers (A) and (B) By using a planetary mixer, the blended materials having the weights shown in Table 1 were mixed and stirred at a temperature of 80 ° C. for 4 to 6 hours to react various polyols and isocyanates. Prepolymers A1 to A16 and prepolymers B1 to B8 were obtained.

(Note 1) Tetraol, Excenol 410NE manufactured by AGC, molecular weight 550
(Note 2A) Triol, AGC Preminol 7003, molecular weight 6200
(Note 2B) Triol, Excel 5030 manufactured by AGC, molecular weight 5100
(Note 3A) Diol, AGC's Exenol 1020, molecular weight 1000
(Note 3B) Diol, AGC Excenol 2020, molecular weight 2000
(Note 4) Diol, AGC's Excenol 420, molecular weight 400
(Note 5) Diol, AGC Excenol 720, molecular weight 700
(Note 6) Diol, Gordo diethylene glycol, molecular weight 100
(Note 7) Diol, Excenol 1020 manufactured by AGC, molecular weight 1000
(Note 8) Isophorone diisocyanate, EVONIK VestantIPDI, molecular weight 222
(Note 9) Tolylene diisocyanate, Mitsui Chemicals Cosmonate T-80, molecular weight 174

  An adhesive was obtained by defoaming, mixing and stirring the blended materials having the weights shown in Table 2 using a planetary mixer.

(Note 10) Amine-based latent curing agent, Sunstar Giken RD-5102H,
(Note 11) DINP, diplusonyl phthalate manufactured by JPLUS (Note 12) Surface treated calcium carbonate + heavy calcium carbonate, Whiteon B manufactured by Shiraishi Calcium Co., Ltd., Sealets 200 manufactured by Maruo Calcium Co., Ltd.
(Note 13) Carbon black, Hiblack # 20 manufactured by EVONIK
(Note 14) c-MDI + diisopropyl malonate, Sumidur 44V20 manufactured by Sumika Bayer Urethane Co., Ltd., diisopropyl malonate manufactured by Tokyo Chemical Industry Co., Ltd. (Note 15) dibutyltin, Neostan U-220H manufactured by Nitto Kasei

  The following performance tests were performed on each adhesive prepared as described above. The results are shown in Table 3.

[performance test]
1. Physical properties An adhesive is sandwiched between release papers and pressed to form a sheet (thickness: 2 mm). The adhesive molded into a sheet is cured by heating for 15 minutes in an oven or press heated to 80 ° C. The cured adhesive is cured at room temperature (20 ° C., 65% RH) for 3 days. The cured adhesive sheet is punched out using a No. 2 dumbbell to obtain a dumbbell sheet. The punched dumbbell sheet is evaluated using a universal tensile testing machine.
Tensile strength determination: ○ = 7.5 Mpa or more, Δ = 7.5 to 6.5 MPa, x = 6.5 MPa or less M50 determination: ○ = 3.0 Mpa or more, x = 3.0 MPa or less Elongation determination: ○ = 200% Above, x = 200% or less

2. Heat resistance The dumbbell sheet produced in the physical property evaluation is heated at 100 ° C. for 30 days using an oven. Next, the dumbbell sheet taken out from the oven is cooled to room temperature, and the above 1. The same test as the physical property evaluation is performed, and the strength at break is measured.
Judgment: ○ = 7.5 Mpa or more, Δ = 7.5 to 6.5 MPa, x = 6.5 MPa or less

3. Storage Stability The adhesive prepared as described above is filled into a 70 cc bottle and heated in an oven heated to 50 ° C. for 3 days. Subsequently, the bottle taken out from the oven was cooled to 20 ° C., and the BH viscometer No. Measure the viscosity at 20 rpm using a 7 rotor.
Judgment: ○ = Viscosity increase rate from the initial stage is 50% or less, Δ = Viscosity increase rate from the initial stage is 50% or more, × = Gelation

From the above results, it can be seen that the adhesives produced in Examples 1 to 20 according to the present invention have good physical properties and heat resistance of the cured product, and good storage stability.
On the other hand, the adhesive which has sufficient tensile strength was not obtained from the comparative example 1 which does not use a curing catalyst.
Moreover, the adhesive by the comparative example 2 using the diol whose number average molecular weight is 200, and the adhesive by the comparative example 3 using the diol whose number average molecular weight is 900 were not able to obtain sufficient tensile strength.
The adhesive according to Comparative Example 4 using only the urethane prepolymer (A) does not provide sufficient storage stability, and the adhesive according to Comparative Example 5 using only the urethane prepolymer (B) has sufficient tensile strength. And heat resistance was not obtained.
The adhesive according to Comparative Example 6 using an aromatic polyisocyanate for the urethane prepolymer (A) and an aliphatic polyisocyanate for the urethane prepolymer (B) did not have sufficient heat resistance and storage stability.
From the result of Comparative Example 7, it can be seen that sufficient storage stability cannot be obtained when an aromatic polyisocyanate is not used in the urethane prepolymer (B). Moreover, it turns out that sufficient heat resistance is not acquired from the result of the comparative example 8 when aliphatic polyisocyanate is not used for a urethane prepolymer (A).
Adhesives according to Comparative Example 9 that does not use tetraol in polyol (A) (1) and Comparative Example 10 that does not use a diol having a number average molecular weight of 300 to 800 do not provide sufficient tensile strength and M50 values. It was.
Adhesives according to Comparative Example 11 in which no diol is used for polyol (B) (1) and Comparative Example 12 in which a polyol having a functionality of 3 or more is not used did not have sufficient tensile strength and M50 values.

Claims (8)

(A) (1) a polyol containing tetraol, triol and a diol having a number average molecular weight of 300 to 800, and (2) a urethane prepolymer obtained by reacting an aliphatic polyisocyanate,
(B) (1) a polyol containing a diol and a tri- or higher functional polyol, and (2) a urethane prepolymer obtained by reacting an aromatic polyisocyanate,
A one-component urethane-based adhesive used for a roof part of an automobile, comprising (C) an amine-based latent curing agent and (D) a curing catalyst.   The polyol (A) (1) comprises 7 to 10 parts by weight of a tetraol and 30 to 50 parts by weight of a diol having a number average molecular weight of 300 to 800, based on 100 parts by weight of a triol. One-component urethane adhesive.   The one-component urethane-based adhesive according to claim 1 or 2, wherein the NCO / OH equivalent ratio of the polyol (A) (1) and the aliphatic polyisocyanate (A) (2) is 1.9 to 2.1. Agent.   The one component according to any one of claims 1 to 3, wherein the NCO / OH equivalent ratio of the polyol (B) (1) and the aliphatic polyisocyanate (B) (2) is 1.9 to 2.1. Type urethane adhesive.   The one-component urethane adhesive according to any one of claims 1 to 4, wherein a weight ratio of the urethane prepolymer (A) and the urethane prepolymer (B) is 35:65 to 65:35.   The one-component urethane adhesive according to any one of claims 1 to 5, wherein the amine-based latent curing agent (C) is a fine powder-coated amine obtained by coating an amine that is solid at 50 ° C with an inorganic powder. Agent.   The one-component urethane adhesive according to any one of claims 1 to 6, wherein the curing catalyst (D) is a tin-based catalyst.   The one-component urethane adhesive according to any one of claims 1 to 7, wherein the aromatic polyisocyanate is TDI.