JP2000239644A - Primer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a primer composition capable of providing good bonding strength, salt water resistance and water resistance by formulating an organoalkoxysilane compound having a glycidyl group and a hydrolyzable alkoxysilane group with water and a hydrophilic organic solvent in a specified ratio so as to form a composition having a specified or smaller angle of contact with the surface of aluminum. SOLUTION: This composition is obtained by mixing 100 pts.wt. organoalkoxysilane compound (A) having a glycidyl group and a hydrolyzable alkoxysilane group with 0.5-20 pts.wt. water (B), and 1-200 pts.wt. hydrophilic organic solvent (C) so as to form a composition having an angle of contact of at most 50 deg. with the surface of aluminum. Component A is desirably 3- glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3- glycidoxypropylmethyldimethoxysilane, or 3-glycidoxypropylmethyldiethoxysilane. Component B is desirably ion-exchanged water having an electric conductivity of 500 μs/cm or below at 25 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primer composition, and particularly to a method for bonding an aluminum alloy and a plastic reinforced with carbon fibers (CFRP).
The present invention relates to a primer applied between an adhesive and an aluminum alloy.

A composite material formed of an aluminum alloy and CFRP is widely used as a structural material because of its light weight and high strength. However, due to the difference in electrical properties between aluminum and carbon fiber, conductive materials such as water and salt water are used. When immersed in an ionic liquid, aluminum was corroded and the adhesive surface was sometimes destroyed. The present invention suppresses this electric corrosion,
The present invention relates to a primer composition which can maintain good adhesiveness and strength as a structural material for a long period of time even under severe use environment.

[0003]

2. Description of the Prior Art Aluminum alloys are used alone or after being subjected to alumite processing and then subjected to electrodeposition coating and the like, and are widely used in construction, automobiles and the like. However, when used alone, the strength is slightly insufficient, and when higher strength is required as a structural material, it is used as a composite material to which CFRP is bonded.

[0004] The adhesion between the aluminum alloy and CFRP is as follows:
This is an extremely important operation and process for exhibiting the strength as a composite material. The bonding process is carried out at room temperature or by heating, and urea resin adhesive, melamine resin adhesive, phenol resin adhesive, α-olefin resin adhesive, epoxy resin adhesive, hot melt adhesive, polyurethane Adhesives, chloroprene rubber-based adhesives, nitrile rubber-based adhesives, SBR-based adhesives, ethylene copolymer resin adhesives (these are 13398 chemical products, see Chemical Daily Co., Ltd. (1998)) and the like. In particular, epoxy resin-based adhesives are frequently used because they cure quickly, have high adhesive strength, do not contain a solvent, and have little shrinkage after curing. It is also well known to cure an epoxy resin-based adhesive using a polyamine compound as a curing agent, and is known to have good workability, curability, and adhesiveness.

[0005] However, if this excellent epoxy resin-based adhesive is applied to the bonding between an aluminum alloy and CFRP, the initial bonding strength is high and good, but the bonded composite material is dipped in water, Alternatively, when immersed in salt water, a phenomenon occurs in which the aluminum alloy is electrically corroded and the bonding surface is destroyed due to the difference in electrical properties between the aluminum alloy and CFRP. That is, this means that such a composite material is hard to withstand use in various changing natural environments.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide an adhesive member capable of exhibiting sufficient strength even in a severe environment. It is an object of the present invention to provide an adhesive member useful for producing a composite material of a strongly bonded aluminum alloy and CFRP.

[0007]

That is, the present invention relates to an organoalkoxysilane compound (A) having a glycidyl group and a hydrolyzable alkoxysilane group in one molecule.
Water (B) 0.5 to 20 parts by weight, and
A primer composition comprising 1 to 200 parts by weight of a hydrophilic organic solvent (C) and having a contact angle of not more than 50 degrees with the aluminum surface.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The organoalkoxysilane compound (A) having a glycidyl group and a hydrolyzable alkoxysilane group in one molecule includes 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. Silane, 3-glycidoxypropyltriisopropoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyldimethoxysilane, etc. These compounds may be used alone or as a mixture of two or more. The compound forms a layer between the adhesive and the aluminum alloy and contributes to greatly improving warm water resistance and salt water resistance of the composite material composed of the aluminum alloy and CFRP.

When the compound is 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane This is preferable since the warm water resistance and the salt water resistance are further improved.

The water (B) may be ordinary drinking water or industrial water, but when it is ion-exchanged water having an electric conductivity at 25 ° C. of 500 μs / cm or less, there is a tendency that warm water resistance, salt water resistance and adhesive strength are improved. Is preferred. That is, it is desirable to avoid ionic impurities, particularly anions, contained in water because they promote the corrosion of aluminum and contribute to a decrease in adhesive strength. Although there is no particular lower limit for the conductivity, it is usually about 0.05 μs / cm.

The water (B) is added in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the organoalkoxysilane compound (A). If the amount is less than 0.5 parts by weight, wettability to aluminum is insufficient, and uniform application cannot be performed. When used in an amount exceeding 20 parts by weight, water remains between the aluminum alloy and the adhesive forever, and the warm water resistance and salt water resistance tend to be rather deteriorated. Water (B) is preferably used in an amount of 1 to 10 parts by weight. At this time, the adhesiveness and salt water resistance are further improved.

Examples of the hydrophilic organic solvent (C) include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and n-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether and propylene glycol monomethyl. Glycol ethers such as ether, propylene glycol n-propyl ether, dipropylene glycol monopropyl ether and the like, which can be mixed with water at any ratio. The compound lowers the surface tension of the primer composition, improves the wettability to the aluminum substrate, and promotes the uniform formation of the primer layer on the aluminum surface. From this point of view, further, a surfactant (a chemical product of 13398,
Pages 193 to 1220, Chemical Daily (19
98)) is also recommended, and nonionic surfactants are particularly preferable in terms of storage stability of the primer.

The hydrophilic organic solvent (C) is used in an amount of 1 to 200 parts by weight based on 100 parts by weight of the organoalkoxysilane compound (A).
Use parts by weight. If the amount is less than 1 part by weight, the surface tension of the primer cannot be sufficiently reduced, so that the wettability to the aluminum base material is deteriorated and the adhesive strength tends to decrease. 200
When used in excess of parts by weight, the amount of solvent discharged at the time of primer application increases, which is not preferable in terms of working environment. Also,
The solvent may easily remain even after the primer is dried and cured, and the adhesive strength may decrease.

Further, in the present invention, an acid catalyst such as hydrochloric acid, sulfuric acid,
Acetic acid and the like can be preferably used. The acid catalyst promotes hydrolysis of the organoalkoxysilane compound and generates a silanol group, so that curability and adhesion to an aluminum alloy are improved.

The primer composition of the present invention needs to have a contact angle with the aluminum surface of 50 degrees or less. If the contact angle exceeds 50 degrees, when the primer is applied to an aluminum substrate, repelling may occur and a uniform film may not be formed. The contact angle with the aluminum substrate is more preferably 40 degrees or less, and at this time, the adhesive strength, salt water resistance and warm water resistance are further improved. The lower limit of the contact angle is 0 degree.

The contact angle of the primer to aluminum was determined by a contact angle meter ("FACE", a contact angle meter manufactured by Kyowa Interface Chemical Co., Ltd.).
CA-D type)) according to a conventional method.

In order to protect the substrate (for example, an aluminum alloy) (to prevent the adhesive from being broken by immersion in salt water or the like), the primer is preferably used in a step before applying the adhesive. That is, it is desirable to apply the adhesive after applying the primer to the base material, and to further join CFRP or the like. At this time, it is more preferable that the adhesive is an epoxy resin-based adhesive, and the adhesive strength, that is, the reliability of the composite material is further improved. Therefore, the present invention also provides a primer composition for an epoxy adhesive containing the above-mentioned organoalkoxysilane compound (A).

It is necessary that the adhesive strength of the adhesive member after salt water immersion be maintained at 80% or more of that before salt water immersion. If it is less than this, the strength and reliability of the composite material are lost. Further, the adhesive strength of the adhesive member after immersion in salt water is desirably 15 MPa or more. If it is reduced to 15 MPa or less, the strength of the composite material is not maintained,
Reliability and safety are lost. The upper limit may be 50 MPa, but is usually about 30 MPa.

The primer composition can be produced by any means as long as the organoalkoxysilane compound (A), water (B) and hydrophilic organic solvent (C) can be uniformly mixed. That is, the organoalkoxysilane compound (A), water (B), and hydrophilic organic solvent (C) may be charged into a container equipped with a stirring device, and stirred and mixed until the mixture becomes uniform.

In the primer composition, if necessary, pigments such as titanium dioxide, carbon black, calcium carbonate, iron oxide, silicon dioxide, toluene, xylene, ethyl acetate, butyl acetate, cyclohexanone, etc.
Organic solvents such as petroleum spirits, dyes, leveling agents, pigment dispersants, paint additives such as ultraviolet absorbers, light stabilizers, etc., and synthetic polymer compounds such as alkyd resins, polyester resins, epoxy resins, acrylic resins, and polyurethane resins ( Those used for paints are more preferred) (see; 1)
Paints and adhesives such as 3398 chemical products, pages 1223 to 1249, Chemical Daily Co. (1998))
Various raw materials and compounds usually blended in the ink may be used in combination. Further, the primer can be mixed and used with the adhesive in order to improve the adhesive strength. At this time, good conformability occurs between the primer and the adhesive, and the adhesive strength and the protective function of the base material are improved.

Further, as can be easily guessed, the primer composition of the present invention is used at the time of bonding aluminum alloy / CFRP, and not only exhibits functions and effects,
Electrically conductive articles and electrical conductive articles, more suitable for bonding and joining two or more types of electrically conductive articles with different electrical conductivity. Demonstrates and prevents bond destruction due to electrical corrosion.

[0022]

【Example】

[0023]

EXAMPLE 1 3-glycidoxypropyltrimethoxysilane 10 was placed in a 200 ml glass beaker equipped with a stirrer.
0 g, ion-exchanged water (conductivity: 1 μs / cm), 10 g, and isopropyl alcohol, 20 g, were stirred and charged.
Was prepared. The contact angle of this primer with aluminum was 40 degrees.

[0024]

Example 2 An additional 0.1 mo was added to the primer of Example 1.
The primer of Example 2 was prepared by adding 0.2 g of 1 / l-HCl. The contact angle of this primer with aluminum was 20 degrees.

[0025]

Example 3 3-glycidoxypropyltrimethoxysilane 10 in a 200 ml glass beaker equipped with a stirrer
0 g, ion-exchanged water (conductivity: 0.8 μs / cm) 0.5
g, isopropyl alcohol 20 g, 0.1 mol / l
0.2 g of HCl was charged and stirred to produce a primer of Example 3. The contact angle of this primer with aluminum was 40 degrees.

[0026]

Example 4 3-glycidoxypropyltrimethoxysilane 10 in a 200 ml glass beaker equipped with a stirrer
0 g, ion-exchanged water (conductivity 1 μs / cm) 20 g, isopropyl alcohol 20 g, 0.1 mol / l-HC
10.2 g was charged and stirred to produce a primer of Example 4. The contact angle of this primer with aluminum was 15 degrees.

[0027]

Example 5 A primer of Example 5 was produced in the same manner as in Example 2, except that propylene glycol monomethyl ether was used instead of isopropyl alcohol. The contact angle of this primer with aluminum was 10 degrees.

[0028]

Example 6 In a 200 ml glass beaker equipped with a stirrer, 3-glycidoxypropyltriethoxysilane 10 was added.
0 g, ion-exchanged water (conductivity: 0.9 μs / cm) 10
g, isopropyl alcohol 20 g, 0.1 mol / l
0.2 g of HCl was charged and stirred to produce a primer of Example 6. The contact angle of this primer with aluminum was 30 degrees.

[0029]

Comparative Example 1 3-glycidoxypropyltrimethoxysilane 10 in a 200 ml glass beaker equipped with a stirrer
0 g and 20 g of isopropyl alcohol were charged and stirred to produce a primer of Comparative Example 1. The contact angle of this primer with aluminum was 60 degrees.

[0030]

Comparative Example 2 3-glycidoxypropyltrimethoxysilane 10 was placed in a 200 ml glass beaker equipped with a stirrer.
0 g, ion-exchanged water (conductivity 1.0 μs / cm) 20 g
Was mixed and stirred to produce a primer of Comparative Example 2. The contact angle of this primer with aluminum is 80 degrees or more (repelling occurs, making measurement difficult).

A test was performed using the above primers. The test items, test methods, and evaluation methods for the results are shown below.
Table 1 shows the test results.

The test was conducted using a 5 mm thick aluminum plate (6063 series (JI
S)), the primers of Examples and Comparative Examples were applied to one side so that the film thickness was 5 μm or less, and dried by heating at 80 ° C. for 60 minutes, and then an epoxy resin adhesive (“Chemit Epoxy TSA2200” (Toray ( Co., Ltd. product)) thickness is 30
５０50 μm, and a tensile strength of 3.5
An epoxy resin matrix CFRP (carbon fiber volume content: 60%, thickness: 1.5 mm) using carbon fibers having GPa and an elasticity of 230 GPa as reinforcing fibers is joined, and is subjected to 48 at room temperature.
The adhesive was cured for a time, and the obtained test piece was used. Adhesive strength: Measured and evaluated according to JIS K-6850. An adhesive strength of 15 MPa or more is considered to be acceptable. Salt water resistance: The test piece was immersed in 5% salt water (25 ° C.) for 240 hours, and the adhesive strength before and after the test was measured. If the retention of the adhesive strength after the test is 80% or more and the adhesive strength is 15 MPa or more, it is judged as acceptable. Water resistance: The test piece was immersed in ion-exchanged water (40 ° C.) having an electric conductivity of 1.0 μs / cm for 240 hours, and the adhesive strength before and after the test was measured. If the retention of the adhesive strength after the test is 80% or more and the adhesive strength is 15 MPa or more, it is judged as acceptable.

[0033]

[Table 1]

[0034]

By treating an aluminum alloy with the primer of the present invention, good performance can be exhibited not only in the initial adhesive strength but also in environmental tests (salt water resistance, water resistance). That is, by using the primer of the present invention, an aluminum / CFRP composite material excellent in practicality can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F006 AA34 AA53 AB39 AB54 AB64 BA01 4J040 EC001 EK051 HD35 KA23 LA06 MA01 MA02 MA10 MB02 PA11 PA12

Claims (6)

[Claims] 1. An organic alkoxysilane compound having a glycidyl group and a hydrolyzable alkoxysilane group in one molecule (A) per 100 parts by weight of water (B) 0.5 to 20 parts by weight and a hydrophilic organic compound A solvent (C) in an amount of 1 to 200 parts by weight;
A primer composition having a temperature of 0 degrees or less. 2. The method of claim 1, wherein the organoalkoxysilane compound (A) is 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylmethyl. The primer composition according to claim 1, which is selected from diethoxysilane. 3. The water (B) having an electric conductivity of 500 at 25 ° C.
The primer composition according to claim 1, wherein the primer composition is ion-exchanged water of μs / cm or less. 4. A primer composition for an epoxy adhesive comprising an organoalkoxysilane compound (A) having a glycidyl group and a hydrolyzable alkoxysilane group in one molecule. 5. An adhesive member for forming a composite of an aluminum alloy and a carbon fiber reinforced plastic, wherein the ratio of the adhesive strength before and after the salt water treatment of the composite is 80% or more. 6. The adhesive member according to claim 5, wherein the adhesive strength after the salt water treatment is 15 MPa or more.