JPH0659456B2 - Adhesion method between urethane elastomer and metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a bonding method for obtaining a bonded product of a urethane elastomer having excellent water resistance and heat resistance and a metal.

Urethane elastomers are used for various industrial materials such as belts and solid tires because of their excellent mechanical properties, abrasion resistance, chemical resistance and the like.

[Conventional technology]

On the other hand, depending on the application of the urethane elastomer, it is often necessary to bond it to a metal. For example, when a thermosetting urethane elastomer represented by adiprene is bonded to a metal, Chemlok 218 or Conap 1146C (both are trade names ) Such as a phenol resin-based primer or other epoxy resin-based primer is used.

However, when these primers are used, it is necessary to heat the urethane elastomer at a temperature of 100 to 120 ° C. for several hours to one day for curing the elastomer and for obtaining sufficient adhesive strength.

Since such a method requires heating at a high temperature for a long time, it is uneconomical in terms of energy and is not preferable in terms of work.
Further, in this case, even if the initial adhesive strength is sufficient, the adhesive strength is largely reduced and satisfactory water resistance can be obtained in applications where it is immersed in warm water for a long period of time, or particularly when it is used in an environment of hot water immersion in which a temperature gradient is applied. I can't.

If a urethane elastomer that can be cured at room temperature or a relatively low heating temperature is used, it is economical in terms of heat energy at the time of curing, but when bonding to a metal, a primer that can be bonded at a low temperature is required.

However, when the above-mentioned phenol resin-based or epoxy resin-based primer is used, good adhesive strength cannot be obtained at a heating temperature lower than 100 ° C, and water resistance and heat resistance are not satisfied, so that it cannot be applied.

The present inventors diligently studied a primer for firmly adhering a urethane elastomer, which cures at a relatively low temperature, to a metal without impairing water resistance and heat resistance.
An adhesion method using a double-coated primer has been developed as shown in JP-A-4475 and JP-A-58-201638.

In the method, first, an epoxy-based primer was applied to the metal surface, then a urethane-based primer was applied, and a urethane elastomer stock solution was poured on the metal primer and adhered at room temperature.

However, the above method has an advantage that it can be bonded at room temperature, but has a drawback that the initial adhesive force is slow to develop. To improve this, heating is applied within a relatively short time after casting the urethane elastomer to accelerate the adhesion. However, it was difficult to obtain sufficient adhesive force by causing foaming and rising at the interface between the urethane primer and the urethane elastomer.

[Object of the Invention]

Therefore, the present inventor further studies in order to obtain a bonded product which is fast in the initial adhesive force and strongly bonded in the case of bonding a urethane elastomer that cures at room temperature or heating to a metal, and which is excellent in water resistance and heat resistance. As a result of overlapping
Two specific types of primers are used, and when they are bonded to a urethane elastomer, they show a strong adhesive force between the urethane elastomer and the metal by heating for a relatively short time, and also heat resistance and water resistance, especially a temperature gradient. The present invention has been accomplished by finding that an adhesive having excellent water resistance below can be obtained.

That is, the present invention applies a primer composition containing a polyepoxy compound and a polyamine compound to a metal surface, and contains 5 to 50% by weight of an isocyanate group on the isocyanate compound or a urethane prepolymer having an isocyanate group at the end. And a primer composition containing a polyepoxy compound, and a urethane elastomer stock solution is poured onto the primer composition to cure and bond the same, and to a method for adhering a urethane elastomer and a metal.

[Structure of the Invention] The present invention will be described in detail below.

In the present invention, two kinds of adhesive compositions are used,
A composition containing a polyepoxy compound and a polyamine compound is called a primary primer, and a composition containing an isocyanate compound and a polyepoxy compound is called a secondary primer.

The primary primer used in the present invention is a two-pack type, and as the polyepoxy compound used as the main component thereof, a terminal epoxy group-containing compound having an average molecular weight of 200 to 10000 obtained by adding epichlorohydrin to bisphenol A, Phenol, cresol,
Phenol compound such as resorcin and formaldehyde,
A polyvalent epoxy compound obtained by reacting a polyphenol resin obtained by condensation with an aldehyde such as glyoxal or acrolein with epichlorohydrin is preferable.

A commercial item can also be used for a polyepoxy compound.
For example, Epicoat 828 manufactured by Yuka Shell Epoxy Co.,
1001, 1004, 1009 or 152, 154
(Epicoat is a trademark), or EPN-1138, 1139 ECN-1 of Araldite manufactured by Ciba Geigy.
235, 1273, 1280 (Araldite is a trademark) and the like. These are used alone or as a mixture.
When more heat resistance is required, a polyfunctional polyphenol epoxy compound is preferable.

As the polyamine compound used for the purpose of polymerizing the epoxy compound as the curing agent component of the primary primer, various known curing agents are used.

For example, a compound containing a terminal amino group synthesized from a dimer acid and a polyamine such as ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, xylylenediamine, for example, versamide 11
5,125,140 (trademark, manufactured by Henkel Japan Ltd.); amines such as diethylenetriamine, tetraethylenepentanemine, hexamethylenediamine, propylenediamine, trimethylhexamethylenediamine, isophoronediamine, mensendiamine, xylylenediamine and these amines. Reaction products with epoxy compounds such as 1,4-butanediol diglycidyl ether, glycerin triglycidyl ether, bisphenol A / diglycidyl ether and diaminocyclodihexylmethane, secondary amines such as dimethylamine and diethylamine, formaldehyde and phenol Compounds obtained by the Mannich reaction with phenols such as cresol and cresol, or the reaction between aldehydes such as aniline and toluidine with aromatic amines and formaldehyde Connexion there is a polyamines obtained.
When more water resistance and heat resistance are required, it is preferable to use an aromatic compound such as xylylenediamine or an epoxy compound or amide compound thereof.

A bisphenol A type epoxy compound obtained by adding epichlorohydrin to bisphenol A as a main agent or a phenol novolak type epoxy compound obtained by reacting a polyphenol compound with epichlorohydrin,
It is preferable to combine xylylenediamine or a modified product thereof having a terminal amino group as a curing agent to form a primary primer.

Furthermore, the following secondary materials can be added to the primary primer. As auxiliary materials, extender pigments (talc, clay, calcium carbonate, calcium sulfate, alumina, silica, calcium silicate, etc.), coloring pigments (titanium oxide, carbon black, iron oxide, lead oxide, ultramarine blue, phthalocyanine blue, etc.), rust prevention Pigments (lead silicate, calcium leadate, lead chromate, etc.) and flow regulators (fine silica, asbestos, hydrogenated castor oil, etc.) can be optionally selected and blended. The main agent, curing agent and auxiliary materials are usually mixed with a solvent to prepare a primary primer.

The solvent is a compound that dissolves both the polyamine compound and the polyepoxy compound, and for example, toluene, xylene, ethylbenzene, methyl ethyl ketone, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, butyl cellosolve, and acetic acid ester of cellosolve compound can be used.

The mixing ratio of the polyepoxy compound and the polyamine compound is in the range of 0.5 / 1 to 1 / 0.5 in terms of equivalent ratio.

The solvent is appropriately adjusted according to workability in such an amount as to make the viscosity easy to apply. Generally, the amount of solvent used is such that the total resin concentration is in the range of 2 to 90% by weight. When a pigment is added, it is preferably 1 to 500% by weight based on the total amount of resin.

Isocyanate compound that is a component of the secondary primer, or the isocyanate group concentration of the urethane prepolymer (weight% of isocyanate group in the isocyanate compound as solid content excluding solvent, hereinafter referred to as NCO%) is 5
50%, preferably 10-35% is used.
At least 2 isocyanate compounds in the same molecule
Aliphatic, alicyclic and aromatic isocyanate monomers having NCO groups, mixtures thereof, and modified products thereof are used. Specific examples include tolylene diisocyanate (2,-and / or 2,6-isomer), xylylene diisocyanate, naphthylene diisocyanate, diphenylmethane diisocyanate (MDI), low polycondensate of aniline and formaldehyde, and phosgene. The polynuclear polyisocyanate (so-called crude MDI) and the carbodiimide-modified diphenylmethane diisocyanate obtained by the above reaction can be mentioned.

In addition, NCs having terminal NCO groups obtained by reacting these isocyanate compounds with polyhydroxy compounds
It is also possible to use a urethane prepolymer having an O group concentration of 5 to 50% by weight (note that the urethane prepolymer is a reaction product of an isocyanate compound and a polyhydroxy compound and contains an unreacted isocyanate compound. NCO% is the weight% of NCO groups contained in the mixture (vs. mixture weight). As the polyhydroxy compound, a polyether polyol or a polyester polyol which is usually used for producing polyurethane is used. For example, polyalkylene having an average molecular weight of 300 to 10,000 obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide or butylene oxide to a polyhydric alcohol such as ethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitol or sucrose. Ether polyol, polyether polyol such as polytetramethylene ether glycol having an average molecular weight of 600 to 10,000 obtained by ring-opening polymerization of tetrahydrofuran, ethylene glycol, propylene glycol, 1,4-butanediol, hexylene glycol, diethylene glycol, Condensation of difunctional alcohols such as dipropylene glycol with difunctional carboxylic acids such as adipic acid, succinic acid, azelaic acid, and phthalic acid. The average polyester polyol having a molecular weight 300～6,000 obtained Te cowpea to the reaction, and a compound having a terminal hydroxy group of average molecular weight 300 to 100,000 obtained by ring-opening polymerization may be mentioned caprolactone.

Normally, an isocyanate compound having an NCO% of 5 to 50% by weight or a urethane prepolymer can be practically used.
Even better adhesives can be obtained by using an isocyanate compound or urethane prepolymer having an O% of 10 to 35% by weight. Further, aromatic polyisocyanates such as MDI, crude MDI, carbodiimide-modified MDI, and urethane prepolymers obtained from these isocyanates are preferable in order to obtain fast adhesiveness.

Furthermore, in the present invention, a polyepoxy compound is essential as a component of the secondary primer, and specific examples thereof include the same as those used in the primary primer, and a compound having an average molecular weight of 200 to 10,000 is selected. .

These polyepoxy compounds are 1 to 300 per 100 parts by weight of the isocyanate compound or urethane prepolymer.
Parts by weight It is preferably used in a proportion of 5 to 100 parts by weight.

As the secondary primer, MDI, crude MDI, carbodiimide-modified MDI alone or a mixture thereof or a urethane prepolymer thereof is used, and as the polyepoxy compound, a bisphenol A type epoxy compound or a phenol novolak type epoxy compound is used. preferable.

Further, in the present invention, the secondary primer is preferably used as a two-pack type like the primary primer, and is composed of an isocyanate compound, a component containing a urethane prepolymer having an isocyanate group at the terminal, and a component containing a polyepoxy compound. It consists of two liquids.

Like the primary primer, the secondary primer is also used with solvent.

Isocyanate compound as the solvent of the secondary primer,
A solvent that dissolves the urethane prepolymer and the polyepoxy compound, respectively, and is inert to the isocyanate group and the epoxy group is used. Examples thereof include toluene, xylene, methyl ethyl ketone, methylene chloride, cellosolve acetate, methyl isobutyl ketone, trichlene, ethyl acetate and butyl acetate. The amount used is 0.4 to 30 times, preferably 0.5 to 30 times the total amount of resin solids.
10 times the weight.

Further, a solvent having a strong swelling action, for example, a compound having a strong polarity such as dimethylformamide, dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone can be used together.

By using the primary primer and the secondary primer of the above composition, it is possible to firmly bond the urethane elastomer and the metal by heating for a relatively short time, and
An adhesive having excellent water resistance (particularly water resistance to which a temperature gradient is applied) and heat resistance can be obtained.

Further, in order to obtain an adhesive having high adhesiveness and water resistance, the primary primer preferably contains a silane coupling agent.

Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane and the like, or γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane. Silane or γ-
A reaction product with mercaptopropyltrimethoxysilane and the like are preferable.

When a silane coupling agent is added, it is preferably 0.01 to 20% by weight based on the total amount of polyepoxy compound and polyamine compound (hereinafter simply referred to as total resin amount).

The urethane elastomer used in the present invention is usually an isocyanate group-containing prepolymer liquid (first liquid) obtained by reacting a polyoxyalkylene polyol or polyester polyol with a polyisocyanate compound, a polyoxyalkylene polyol, or a polyester polyol and a chain. Mixed liquid containing extender, catalyst, etc. (second liquid)
(These liquids are referred to as urethane elastomer stock solutions) and the mixture is cast.

The polyoxyalkylene polyol in the first liquid and the second liquid was obtained by adding ethylene oxide, propylene oxide, butylene oxide, etc. to ethylene glycol, propylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, etc. A compound or a compound obtained by ring-opening polymerization of tetrahydrofuran is preferable, and the average molecular weight is 700 to 10,000.
Those of are preferably used.

Polyester polyols include difunctional alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, hexylene glycol, diethylene glycol and dipropylene glycol, and dicarboxylic acids such as adipic acid, succinic acid, azelaic acid and phthalic acid. Average molecular weight 700 obtained by ring-opening polymerization of a compound having a terminal hydroxy group having an average molecular weight of 700 to 6,000 obtained by condensation reaction with a bifunctional carboxylic acid and caprolactone
A compound having a terminal hydroxy group of ˜6,000 is preferably used. These glycols and acids may be used alone or in combination. The polyoxyalkylene polyol or polyester polyol may be used alone or in combination of two or more kinds.

As the polyisocyanate compound used as the raw material of the prepolymer of the first liquid, diisocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate and naphthalene diisocyanate, and compounds obtained by partially converting carbodiimidization of diphenylmethane diisocyanate are preferable.

The isocyanate group concentration of the prepolymer is 2 to 25%, and the more preferable concentration is 2 to 1 from the reaction rate and the property of the casting.
5%.

As the chain extender, short chain diols such as ethylene glycol, 1,4-butanediol, dipropylene glycol, hexylene glycol, and aromatic diamines such as methylenebis (0-chloroaniline) and methylenedianiline can be used.

The catalyst is a tertiary amine catalyst or tin octoate, which is generally used to accelerate the urethanization reaction such as diazabicyclooctane.
Dibutyltin dioctoate, dibutyltin dilaurate,
It is an organometallic compound such as lead octoate that is generally used to accelerate the urethane reaction.

The method of the present invention is particularly preferably used for bonding a urethane elastomer, which cures at room temperature or by heating, to a metal. Examples of the metal to which the urethane elastomer is adhered include iron, stainless steel, aluminum and magnesium.

The method for adhering the metal and the elastomer is as follows.

First, each component of the primary primer is mixed with a solvent, and the resulting mixed liquid has a thickness after drying of 5 to 200 μm, preferably 1 μm.
It is applied to a metal in an amount of 0 to 100 μm, and is left for 2 hours or longer at 20 ° C. and left for 30 minutes or longer when heated to about 60 ° C. Further, if the coated article is heated at a high temperature, the water resistance of the adhesive will be improved. If the surface of the coated material becomes tack-free, the solution in which each component of the secondary primer is mixed with the solvent is applied in an amount such that the thickness after drying is 200 μ or less, preferably 10 to 100 μ, and the solvent is scattered. At room temperature, it is usually left for 3 hours or less, but warm air drying is preferable in order to sufficiently remove the solvent. Then, a urethane elastomer stock solution prepared by mixing the first solution and the second solution is poured and cured. Then 60 to 120 ° C., preferably 70 to 100
When post-heated at about 1 hour for about 1 week and left at room temperature for about 1 week, the physical properties of the elastomer are stabilized and sufficient adhesive strength is obtained.

〔Example〕

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Production Example 1 <Production of primary primer> 300 g of Epicoat 1001 (produced by Yuka Shell Co., bisphenol A type epoxy resin, epoxy equivalent 450-500, trade name) in a three-neck separable flask, xylene 1
50 g was charged and stirred under reflux at 60 ° C. to uniformly dissolve the mixture.

After cooling, Epicoat 152 (produced by Yuka Shell Co., Ltd., phenol novolac type epoxy resin, epoxy equivalent 172 to 17)
9) 140 g and KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd., silane coupling agent) 10 g were added and stirred to obtain a uniform solution.

Next, rutile type titanium oxide 340 was added to this solution as a pigment.
g, talc 50 g, Aerosil # 20 as flow regulator
0 (manufactured by Nippon Aerosil Co., Ltd., finely divided silica, trade name) 10 g
Was added and premixed, followed by kneading with a three-roll mill to produce the main component of the primary primer.

270 g of meta-xylylenediamine (manufactured by Mitsubishi Gas Chemical Company)
And Epicoat 828 (made by Yuka Shell Co., bisphenol A type epoxy resin, epoxy equivalent 184-194) 60
90 g with stirring under dry nitrogen in a flask.
After reacting at 5 ° C for 5 hours and allowing to cool, the reaction product contains xylene 29
0 g, 90 g of ethyl cellosolve and 170 g of methyl ethyl ketone were added to obtain a uniform solution.

This solution was used as the curing agent for the primary primer.

Production Example 2 <Production of primary primer> 220 g of Epicoat 828 (manufactured by Yuka Shell Co., bisphenol A type epoxy resin, epoxy equivalent 184-194) in a three-neck separable flask, Epicoat 152
(Yenka Shell Co., Ltd., phenol novolak type epoxy resin, epoxy equivalent 172 to 179), xylene 150
and 10 g of KBM-403 (Shin-Etsu Chemical Co., Ltd., a silane coupling agent) were charged and stirred to obtain a uniform solution.

In this solution, 340 g of rutile type titanium oxide as a pigment,
After adding 50 g of talc and 10 g of Aerosil # 200 (manufactured by Nippon Aerosil Co., Ltd., fine silica powder) and pre-mixing them, 3
The mixture was kneaded with this roll to produce the base material of the primary primer.

As the curing agent, the one obtained in Production Example 1 was used in common.

Production Examples-3 to 9 <Production of Secondary Primer> Polyisocyanate compound and polyhydroxy compound were reacted in a solvent or without solvent in a three-neck separable flask at 70 ° C. for 4 hours under dry nitrogen encapsulation to obtain a urethane prepolymer. A polymer was produced. A component containing a polyisocyanate compound or a urethane prepolymer was used as liquid A. Table 1 shows the type and amount (g) of the raw material used in the liquid A and the isocyanate group content (expressed as NCO%) in terms of solid content.

Further, a component prepared by uniformly dissolving the polyepoxy compound in a solvent was used as the liquid B. The types and amounts (g) of the raw materials used for the liquid B are also shown in Table-1.

Production Example-10 <Production of Urethane Elastomer Stock Solution> Polytetramethylene ether glycol having an average molecular weight of 1000 (hereinafter referred to as PTMG1000) 10 kg and 80
-TDI (2.4 units 80%, 2,6 units 20% tolylene diisocyanate) (5 kg) was mixed and reacted at 70 ° C for 4 hours to obtain an isocyanate group concentration (hereinafter, referred to as NCO concentration) of 10.3%. A urethane prepolymer liquid having a terminal isocyanate group was obtained. The obtained reaction liquid was cooled to 30 ° C. and stirred under reduced pressure of 20 mmHg to remove dissolved air. This stock solution is called T solution.

On the other hand, 7.5 kg of PTMG1000 and methylenebis (o
(Chloroaniline) (2.5 kg) and diazabicyclooctane (30 g) were mixed and heated to 100 ° C. to obtain a uniform liquid. This stock solution was cooled to 30 ° C. and stirred under a reduced pressure of 20 mmHg to remove dissolved air. This liquid is called R liquid.

Production Example-11 <Production of Undiluted Urethane Elastomer> 10 kg of PTMG1000 and diphenylmethane diisocyanate (trade name: Isonate 125, manufactured by Uppzyon Co., Ltd.)
M) 10 kg are mixed and reacted in the same manner as in Production Example 1,
A urethane prepolymer liquid having an isocyanate group with an NCO concentration of 12.5% was obtained. This stock solution was treated in the same manner as in Production Example 1. This undiluted solution is called M solution.

On the other hand, 870 g of PTMG1000, 130 g of 1,4-butanediol and 0.1 g of dibutyltin dilaurate were mixed and heated to 50 ° C. to obtain a uniform mixed liquid. This stock solution was treated in the same manner as in Production Example 1. The obtained stock solution is called Solution G.

Example 1 After coating a 70 × 150 × 3.2 mm steel plate degreased with trichlene by sandblasting, the primary primer obtained by uniformly mixing 150 g of the main agent and 50 g of the curing agent obtained in Production Example 1 was used as a bar coater No. 60. To a uniform thickness and dried in an oven at 80 ° C. for about 30 minutes. At this time, the dry film thickness of the primary primer was about 40 μm.

Then, the secondary primer A solution 100 obtained in Production Example-3
bar coater No. 6
0 is applied evenly on it and left at room temperature for 10 minutes, then 8
The solvent was removed in an oven at 0 ° C. for about 10 minutes. The dry film thickness of the secondary primer at this time was about 30 μm.

Urethane elastomer stock solution obtained in Production Example-10, T solution 3
After defoaming 00 g and 200 g of R solution at 30 ° C. under a reduced pressure of 20 mmHg for about 20 minutes, mix them for about 1 minute without agitating air with a stirrer, and apply the resulting mixed solution to the secondary primer previously applied. It was poured into the above to a thickness of about 6 mm, cured, and after 1 hour, heated at 80 ° C. for 1 hour.

Thereafter, the adhesive was cured at 23 ° C. and 60% RH (relative humidity) for 1 week.

<Measurement method of initial adhesive strength> When measuring the initial adhesive strength of the adhesive, make a slit parallel to the steel plate surface with a width of 20 mm in the longitudinal center of the test piece, peel off one end and make a grip, and make an angle of 90 °. At 50
The peel strength was measured at a speed of mm / min.

The peel strength of the test piece was 20 kg / cm or more, which showed cohesive failure of the elastomer.

<Measurement Method of Water-Resistant Adhesive Strength> The water resistance of the adhesive was evaluated by the following two tests.

Temperature gradient test The urethane elastomer side of the test piece was brought into contact with warm water of 50 ° C, the back surface of the adhered steel plate was kept at 25 ° C with tap water, and left for 30 days in a state where water transfer between front and back was blocked, The 90 ° peel strength was measured by the method.

Hot water immersion test After sealing the end of the test piece with a sealing material, 50
After being immersed in warm water of ℃ for 30 days at a uniform temperature, 90 ° peel strength was measured by the above method.

Table 2 shows the adhesion test results. In each case, the initial adhesion was 20 kg / cm or more and the cohesive failure of the elastomer occurred to show good adhesion, and the water-resistant adhesion was also determined by the temperature gradient test and the hot water immersion test. After 30 days each, a good adhesive strength of 10 kg / cm to 20 kg / cm or more was retained. When the adhesive strength against water was 20 kg / cm or more, the elastomer was completely destroyed as in the initial adhesion.

Examples-2 to 10 The urethane elastomer was adhered to the steel sheet in the same manner as in Example 1 using the primary primer, secondary primer and urethane elastomer shown in Table-2. The peel strength of the adhesive was measured in the same manner as in Example 1. The results are shown in Table-2.

The blending amount of each blending component is as follows.

<Primer> Main agent Examples 2 to 10 150 g Curing agent Examples 2 to 7 and 1050 g Examples 8 and 975 g <Secondary primer> <Urethane Elastomer> First Liquid Example 2 to 10 300 g Second Liquid Example 2 to 8 200 g 〃 9, 10 180 g Comparative Examples 1 to 3 A steel plate treated in the same manner as in the example was put on a commercially available Chemlock 218.
Dilute 100 g (made by Lord Corporation, phenol type primer) with 100 g of methyl ethyl ketone,
After coating using a bar coater # 100, drying at 70 ° C. for 30 minutes, allowing to cool, and then coating and drying in the same manner as above, the above-mentioned two-component urethane elastomer consisting of liquid T and liquid R is added. 1 hour after injection and curing in the same manner as at 100 ° C
After heating for 1 to 3 hours, an adhesive was obtained. The dry film thickness of the primer at this time was about 40 μm.

Table 3 shows the results of the adhesion test.

Although the initial adhesive strength is relatively good, in the water-resistant adhesiveness, after 30 days of hot water immersion test, 100 ° C for 2 hours or 3
It was good when it was heated for a period of time, but in the temperature gradient test, the adhesive strength had already been lost after 14 days, and it was poor.

Comparative Example 4 Chemlock 218 was applied to a steel plate treated in the same manner as above, and the steel plate was preheated to 110 ° C. TDI-1
1000 g of PTMG1000 was dropped to 250 g of 00 (containing about 100% of 2,4-tolylene diisocyanate) 8
Undiluted solution 400 obtained by reacting a urethane prepolymer having an isocyanate group at the terminal with an NCO concentration of 2.8% at 0 ° C. for 3 hours and keeping it at 80 ° C. and defoaming it under a reduced pressure of 10 mmHg.
To g, 30 g of Kyuamine M (manufactured by Ihara Chemical Co., general name MOCA) melted at 120 ° C. was added, and a mixed solution was mixed for about 1 minute with a stirrer so as not to entrap air bubbles. It was injected to a thickness of 6 mm and cured at 110 ° C. for 4 hours.

As a result of examining the adhesive strength of the obtained adhesive, as shown in Table 3, the initial adhesive strength was satisfied, but the water resistant adhesive strength in the temperature gradient test was extremely poor.

[Effects of the Invention] As described above, according to the present invention, a urethane elastomer and a metal that exhibit good adhesive strength in a short heating time, are excellent in heat resistance, and are particularly excellent in water resistance under an environment in which a temperature gradient exists. It is possible to obtain an adhesive with.

Claims (1)

[Claims] 1. A primary primer composition containing a polyepoxy compound and a polyamine compound is applied to a metal surface,
Containing 5 to 50% by weight of an isocyanate group,
A urethane elastomer and a metal, characterized in that an isocyanate compound or a urethane prepolymer having an isocyanate group at the terminal and a secondary primer composition containing a polyepoxy compound are applied, and then a urethane elastomer stock solution is injected and cured. How to bond with.