JP6139373B2 - Primer composition for aluminum alloy and adhesive member - Google Patents

Description

  The present invention relates to a primer composition, and more particularly to a primer applied between an adhesive and an aluminum alloy when bonding an aluminum alloy and a carbon fiber reinforced plastic (CFRP).

  Composite materials formed from aluminum alloys and CFRP are light and strong, and are widely used as structural materials. However, due to the difference in electrical properties between aluminum and carbon fibers, they are used as conductive liquids such as water and salt water. When soaked, aluminum was electrocorroded and the bonded surface could be destroyed. The present invention relates to a primer composition that suppresses this electric corrosion and can maintain good adhesion and strength as a structural material over a long period of time even under severe use environment.

  Aluminum alloys are widely used in architecture, automobiles, etc., either alone or after being anodized and then subjected to electrodeposition coating. However, the strength is somewhat insufficient by itself, and when higher strength is required as a structural material, it is used as a composite material bonded with CFRP.

  Adhesion between an aluminum alloy and CFRP is an extremely important operation and process for exerting strength as a composite material. The bonding process is carried out at room temperature or with heating. As the adhesive, urea resin adhesive, melamine resin adhesive, phenol resin adhesive, α-olefin resin adhesive, epoxy resin adhesive, hot melt adhesive, polyurethane Adhesives, chloroprene rubber adhesives, nitrile rubber adhesives, SBR adhesives, ethylene copolymer resin adhesives (see 13398 chemical products, Chemical Industry Daily (1998)). In particular, epoxy resin adhesives are frequently used because they cure quickly, have high adhesive strength, do not contain solvents, and have little shrinkage after curing (for example, Patent Document 1). In addition, epoxy resin adhesives are well known to cure polyamine compounds as curing agents, and are said to have good workability, curability and adhesiveness.

  However, even if this excellent epoxy resin adhesive is applied to the adhesion between an aluminum alloy and CFRP, the initial adhesive strength is high and good. However, when the bonded composite material is immersed in water, In the case of dipping in the aluminum alloy, due to the difference in electrical properties between the aluminum alloy and CFRP, a phenomenon occurs in which the aluminum alloy is electrically corroded and the bonded surface is destroyed (for example, Patent Document 2). That is, this means that such a composite material is difficult to be used in a natural environment where various changes occur.

JP 2009-255429 A JP 2011-073191 A

  An object of the present invention is to provide a primer composition for an aluminum alloy that can solve the above-described problems of the prior art and that can exhibit sufficient strength even in a harsh environment, and more specifically, an adhesive member. It is an object to provide an aluminum alloy primer composition and an adhesive member useful for producing a composite material of an aluminum alloy and CFRP bonded to each other.

  That is, the aluminum alloy primer composition of the present invention comprises a hydrolyzed condensate (A) composed of methyltrimethoxysilane, phenyltrimethoxysilane, and a glycidoxyalkyltrialkoxysilane compound, and water (B). The contact angle with respect to the aluminum alloy surface is 50 degrees or less.

  In the primer composition for an aluminum alloy of the present invention, the glycidoxyalkyltrialkoxysilane compound further comprises 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, glycidoxyethyltrimethoxy. It is selected from silane and glycidoxyethyltriethoxysilane.

  The primer composition for an aluminum alloy according to the present invention further includes 0.5 to 20 parts by weight of the water (B) and a hydrophilic organic solvent (C) with respect to 100 parts by weight of the hydrolysis condensate (A). 1) to 200 parts by weight.

  The adhesive member of the present invention is an adhesive member in which the aluminum alloy and the carbon fiber reinforced plastic are combined through the primer composition described above, and the aluminum alloy and the carbon fiber reinforced plastic before and after the salt water treatment The adhesive strength ratio is 90% or more.

  The adhesive member of the present invention is further characterized in that the adhesive strength after the salt water treatment is 15 MPa or more.

  By treating the aluminum alloy with the primer of the present invention, good performance is exhibited in adhesive strength and environmental tests.

As the glycidoxyalkyltrialkoxysilane compound constituting the hydrolysis condensate (A) comprising methyltrimethoxysilane, phenyltrimethoxysilane and glycidoxyalkyltrialkoxysilane compound, 3-glycidoxypropyltrimethoxysilane is used. 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltriisopropoxysilane, glycidoxyethyltrimethoxysilane, glycidoxyethyltriethoxysilane, and the like. 3-Glycidoxypropyltrimethoxysilane is preferred from the standpoint of reactivity and material availability. The hydrolysis condensate (A) forms a layer between the adhesive and the aluminum alloy, and contributes to greatly improving the warm water resistance and salt water resistance of the composite material composed of the aluminum alloy and CFRP.
When the ratio of the glycidoxyalkyltrialkoxysilane compound constituting the hydrolysis-condensation product is 25 to 50 mol%, it is preferable because warm water resistance and salt water resistance are further improved.

  The water (B) may be normal drinking water or industrial water, but is preferably ion-exchanged water having an electric conductivity at 25 ° C. of 500 μs / cm or less because it tends to improve resistance to warm water, salt water, and adhesive strength. . That is, it is desirable to avoid ionic impurities contained in water, particularly anions, because they promote corrosion of the aluminum alloy. The lower limit of the conductivity is not particularly limited, but is usually about 0.05 μs / cm.

  Water (B) is blended in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the hydrolyzed condensate (A) composed of methyltrimethoxysilane, phenyltrimethoxysilane, and glycidoxyalkyltrialkoxysilane compound. When the amount is less than 0.5 part by weight, the wettability with respect to the aluminum alloy is insufficient, and it may not be possible to apply uniformly. When it is used in excess of 20 parts by weight, water remains indefinitely between the aluminum alloy and the adhesive, and the warm water resistance and salt water resistance tend to deteriorate rather. Water (B) is preferably used in an amount of 1 to 10 parts by weight. At this time, 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, propylene glycol monomethyl ether, propylene Glycol ethers such as glycol n-propyl ether and dipropylene glycol monopropyl ether, acetone, tetrahydrofuran, methyl ethyl ketone and the like that can be mixed with water at an arbitrary ratio. The compound lowers the surface tension of the primer composition, improves the wettability to the aluminum alloy, and promotes the uniform formation of the primer layer on the aluminum alloy surface. From this point of view, addition of a surfactant (for example, 13398 chemical products, pages 1193 to 1220, Chemical Industry Daily (1998)) is also recommended, and in particular, a nonionic interface in terms of primer storage stability. An activator is preferred.

  The hydrophilic organic solvent (C) is used in an amount of 1 to 200 parts by weight per 100 parts by weight of the hydrolyzed condensate (A) composed of methyltrimethoxysilane, phenyltrimethoxysilane and glycidoxyalkyltrialkoxysilane compound. If the amount is less than 1 part by weight, the surface tension of the primer cannot be sufficiently lowered, the wettability to the aluminum alloy is deteriorated, and the adhesive force tends to be lowered. When it is used in excess of 200 parts by weight, the amount of solvent discharged becomes large when the primer is applied, which is not preferable in terms of the working environment. In addition, the solvent tends to remain even after the primer is dried and cured, and the adhesive strength may decrease.

Furthermore, in the present invention, an aluminum-based catalyst or a tin-based catalyst can be used to accelerate the curing of the primer. Examples of the aluminum catalyst include aluminum trisacetylacetonate, aluminum bisethylacetoacetate / monoacetylacetonate, ethylacetoacetate aluminum diisopropylate, and aluminum isopropylatebis (oleyl acetoacetate). Examples of the tin-tin catalyst include dibutyltin diacetate, bis (acetoxydibutyltin) oxide, bis (lauroxydibutyltin) oxide, dibutyltin bisacetylacetonate, dibutyltin bismaleic acid monobutyl ester, dioctyl bismaleic acid monobutyl ester Etc.
The amount of the catalyst used is preferably 0.1 ppm to 10% with respect to the mass of the hydrolysis-condensation product (A). A more preferred upper limit is 5%.

The primer composition of the present invention needs to have a contact angle of 50 degrees or less with respect to the aluminum alloy surface. When the contact angle exceeds 50 degrees, when the primer is applied to the aluminum alloy, repellency may occur and a uniform film may not be formed. The contact angle with respect to the aluminum alloy is more preferably 40 ° or less, and further preferably 30 ° or less. At this time, adhesive strength, salt water resistance, and warm water resistance are further improved. The lower limit value of the contact angle is 0 degree.
The contact angle of the primer with respect to the aluminum alloy is measured by a contact angle meter (contact angle meter “FACECA-D type” manufactured by Kyowa Interface Chemical Co., Ltd.) according to a conventional method.

  In order to protect a substrate (for example, an aluminum alloy) (to prevent adhesion failure due to immersion in salt water), the primer composition is preferably used in a pre-process for applying an adhesive. That is, it is desirable to apply the primer composition to the substrate surface (aluminum alloy surface), then apply the adhesive, and then join CFRP (carbon fiber reinforced plastic) or the like. At this time, the adhesive is more preferably an epoxy resin-based adhesive, and the adhesive strength, that is, the reliability of the composite material is further improved. A base material (aluminum alloy), a primer composition applied to the surface of the base material, an adhesive applied on the primer composition, and the base material and the adhesive are sandwiched and combined with the base material. An adhesive member is constituted by CFRP (carbon fiber reinforced plastic). Therefore, the primer composition of the present invention is a primer composition for an epoxy adhesive containing the hydrolysis condensate (A) comprising the above-mentioned methyltrimethoxysilane, phenyltrimethoxysilane, and glycidoxyalkyltrialkoxysilane compound. Will also provide.

  It is necessary to maintain 80% or more of the adhesive strength of the adhesive member after immersion in salt water before immersion in salt water. If it becomes less than this, the strength and reliability of the composite material are lost. Furthermore, the adhesive strength after the adhesive member is immersed in salt water is preferably 15 MPa or more. If the pressure drops to 15 MPa or less, the strength of the composite material is not maintained, and reliability and safety are lost. The upper limit may be 50 MPa, but is usually about 30 MPa.

  The primer composition can be any mixture of hydrolyzed condensate (A), water (B), and hydrophilic organic solvent (C) composed of methyltrimethoxysilane, phenyltrimethoxysilane, and glycidoxyalkyltrialkoxysilane compound. It can also be manufactured by such means. That is, the hydrolysis condensate (A), water (B), and hydrophilic organic solvent (C) may be charged into a container equipped with a stirrer and stirred and mixed until uniform.

  In addition to these, primer compositions include pigments such as titanium dioxide, carbon black, calcium carbonate, iron oxide, and silicon dioxide, and organic compounds such as toluene, xylene, ethyl acetate, butyl acetate, cyclohexanone, and petroleum spirit. Paint additives such as solvents, dyes, leveling agents, pigment dispersants, UV absorbers, light stabilizers, synthetic polymer compounds such as alkyd resins, polyester resins, epoxy resins, acrylic resins, polyurethane resins (used for coatings) (Refer to: Chemical product of 13398, pages 1223 to 1249, Chemical Industry Daily (1998)), etc., together with various raw materials and compounds that are usually blended in inks and inks. You can also. It is also possible to use a primer mixed with the adhesive in the sense of improving the adhesive strength of the adhesive. 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.

  Furthermore, as easily guessed, the primer composition of the present invention is used as a base for an adhesive when bonding an aluminum alloy and CFRP (carbon fiber reinforced plastic) with an adhesive, thereby providing functions and effects. Not only does it exhibit, but it is also suitable for electrically conductive articles and electrically conductive articles, more suitable for bonding and joining two or more types of electrically conductive articles with different electrical conductivities. In addition, it exhibits high adhesive strength and prevents bond breakage due to electrical corrosion.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Unless otherwise specified, parts and% in the examples are based on mass.

Production Example 1 Production of Hydrolysis Condensate of Methyltrimethoxysilane 408 parts of methyltrimethoxysilane were dissolved in 450 parts of isopropyl alcohol. After adding 162 parts of water having the same number of moles as the number of moles of the methoxysilyl group and 1 part of hydrochloric acid as an acid catalyst, the mixture was stirred at 40 ° C. for 1 hour and further stirred at 75 ° C. for 1 hour. To obtain a hydrolyzed condensate of methyltrimethoxysilane. In the analysis by IR, the absorption of C—H based on the methoxysilyl group was not confirmed.

Production Example 2 Production of Hydrolyzed Condensate of Phenyltrimethoxysilane 595 parts of phenyltrimethoxysilane was dissolved in a mixed solution of 200 parts of isopropyl alcohol and 400 parts of toluene. After adding 162 parts of water having the same number of moles as the number of moles of the methoxysilyl group and 1 part of hydrochloric acid as an acid catalyst, the mixture was stirred at 40 ° C. for 1 hour and further stirred at 75 ° C. for 1 hour. And concentrated to obtain a hydrolyzed condensate of phenyltrimethoxysilane. In the analysis by IR, the absorption of C—H based on the methoxysilyl group was not confirmed.

Production Example 3 Production of Hydrolysis Condensate of Glycidoxyalkyltrialkoxysilane 460 parts of glycidoxypropyltrimethoxysilane were dissolved in 390 parts of isopropyl alcohol. After adding 105 parts of water having the same number of moles as the number of moles of methoxysilyl group and 1 part of hydrochloric acid as an acid catalyst, the mixture was stirred at 40 ° C. for 1 hour, and further stirred at 75 ° C. for 1 hour. And concentrated to obtain a hydrolyzed condensate of glycidoxypropyltrimethoxysilane. In the analysis by IR, the absorption of C—H based on the methoxysilyl group was not confirmed.

Example 1
Dissolve 47.7 parts of methyltrimethoxysilane, 69.4 parts of phenyltrimethoxysilane and 79.8 parts of glycidoxypropyltrimethoxysilane in 154 parts of a 2/1 (mass ratio) mixture of isopropyl alcohol and methyl isobutyl ketone. did. To this, 56.7 parts of water having the same number of moles as the number of methoxysilyl groups in the system and 1 part of hydrochloric acid as an acid catalyst were added, stirred at 40 ° C. for 2 hours, and further at 80 ° C. for 3 hours. After stirring, it was concentrated to obtain a polysilanol composition. In the analysis by IR, the absorption of C—H based on the methoxysilyl group was not confirmed. It was confirmed by H-NMR analysis that epoxy groups derived from glycidoxypropyltrimethoxysilane remained.

  100 parts of the resulting polysilanol composition was added to 50 parts of a 1/4 (mass ratio) mixture of tetrahydrofuran and ethoxyethanol and dissolved, and then 10 parts of water was added to prepare a primer. The contact angle of this primer with respect to aluminum was 40 degrees.

Example 2
In Example 1, the polysilanol composition was changed except that the amount of methyltrimethoxysilane was changed to 143.1 parts, the amount of water was changed to 94.5 parts, and the amount of hydrochloric acid was changed to 2 parts. I got a thing. In the analysis by IR, the absorption of C—H based on the methoxysilyl group was not confirmed. It was confirmed by H-NMR analysis that epoxy groups derived from glycidoxypropyltrimethoxysilane remained.

  100 parts of the resulting polysilanol composition was dissolved in 50 parts of a 1/4 (mass ratio) mixture of tetrahydrofuran and ethoxyethanol, and then 10 parts of water and 5 parts of aluminum trisacetylacetonate as an aluminum-based curing catalyst were added. A primer was prepared by addition. The contact angle of this primer with respect to aluminum was 40 degrees.

Example 3
19 parts hydrolyzed condensate of methyltrimethoxysilane obtained in Production Example 1, 37 parts of hydrolyzed condensate of phenyltrimethoxysilane obtained in Production Example 2, and glycidoxypropyltrimethyl obtained in Production Example 3 47 parts of hydrolyzed condensate of methoxysilane was added to 50 parts of a 1/4 (mass ratio) mixture of tetrahydrofuran and ethoxyethanol and dissolved, then 10 parts of water and 5 parts of aluminum trisacetylacetonate as an aluminum-based curing catalyst Was added to produce a primer. The contact angle of this primer with respect to aluminum was 40 degrees.

Comparative Example 1
100 parts of the hydrolyzed condensate of methyltrimethoxysilane obtained in Production Example 1 was added to 50 parts of a 1/4 (mass ratio) mixture of tetrahydrofuran and ethoxyethanol, dissolved, and then 10 parts of water and an aluminum-based curing catalyst. As a comparative primer, 5 parts of aluminum trisacetylacetonate was added. The contact angle of this primer with respect to aluminum was 40 degrees.

Comparative Example 2
100 parts of the hydrolyzed condensate of phenyltrimethoxysilane obtained in Production Example 2 was added to 50 parts of a 1/4 (mass ratio) mixture of tetrahydrofuran and ethoxyethanol, dissolved, and then 10 parts of water and an aluminum-based curing catalyst. As a comparative primer, 5 parts of aluminum trisacetylacetonate was added. The contact angle of this primer with respect to aluminum was 40 degrees.

Comparative Example 3
34 parts of the hydrolyzed condensate of methyltrimethoxysilane obtained in Production Example 1 and 66 parts of the hydrolyzed condensate of phenyltrimethoxysilane obtained in Production Example 2 were mixed with 1/4 (mass ratio) of tetrahydrofuran and ethoxyethanol. ) After dissolving by adding 50 parts of the mixture, 10 parts of water was further added to produce a comparative primer. The contact angle of this primer with respect to aluminum was 40 degrees.

Comparative Example 4
29 parts of the hydrolyzed condensate of methyltrimethoxysilane obtained in Production Example 1 and 71 parts of the hydrolyzed condensate of glycidoxypropyltrimethoxysilane obtained in Production Example 3 were mixed with 1/4 of tetrahydrofuran and ethoxyethanol. (Mass ratio) After dissolving in addition to 50 parts of the mixture, 10 parts of water and 5 parts of aluminum trisacetylacetonate as an aluminum-based curing catalyst were added to produce a comparative primer. The contact angle of this primer with respect to aluminum was 40 degrees.
A test was performed using the above primers. The test items, test methods, and results evaluation methods are shown below. The test results are shown in Table 1.

  In the test, the primer obtained in Examples 1 to 3 and the comparative primer obtained in Comparative Examples 1 to 4 were coated on one side of a 5 mm thick aluminum plate material (6063 series (JIS)) that was degreased with toluene. After coating to a thickness of 5 μm or less, heat drying at 150 ° C. for 2 hours, and heat drying, an epoxy resin adhesive (“Chemit Epoxy TSA2200” (product of Toray Industries, Inc.)) having a thickness of 30 An epoxy resin matrix CFRP (carbon fiber volume content 60%, thickness 1.5 mm) with carbon fiber having a tensile strength of 3.5 GPa and an elastic modulus of 230 GPa as a reinforcing fiber is bonded thereto. Then, the adhesive was cured at room temperature for 48 hours, 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 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. The adhesive strength retention after the test is 90% or more and the adhesive strength is 15 MPa or more.

  Salt water resistance: The specimen was immersed in 5% salt water (25 ° C.) for 240 hours, and the adhesive strength before and after the test was measured. The adhesive strength retention after the test is 90% or more and the adhesive strength is 15 MPa or more.

  Water resistant paint resistance: The test piece was immersed in an aqueous paint (for example, about 70% of water, about 20% of an organic solvent, the rest being a pigment or the like) (45 ° C.) for 240 hours, and the adhesive strength before and after the test was measured. The adhesive strength retention after the test is 90% or more and the adhesive strength is 15 MPa or more.

The aluminum alloy and CFRP bonding material using the primer of the example of the present invention also had good water resistance, salt water resistance, and water resistance paint resistance.
On the other hand, the bonding material using the comparative primer has problems. That is, in Comparative Examples 1, 2, and 3 that do not use glycidoxyalkyltrialkoxysilane, not only the initial bonding strength of the obtained bonding material was reduced, but also water resistance, salt water resistance, and water resistance paint resistance. Also decreased significantly. Further, in Comparative Example 4 comprising a mixture of hydrolyzed condensates of methyltrimethoxysilane and glycidoxypropyltrimethoxysilane as a component, compared to Examples 1, 2, and 3, the water resistance paint resistance was lowered. Was seen.

  By treating the aluminum alloy with the primer of the present invention, not only initial adhesive strength but also environmental performance (water resistance, salt water resistance, water resistance paint resistance) can be exhibited. That is, by using the primer of the present invention, it is excellent in practicality that can be suitably used not only in the fields of conventional architecture and automobiles, but also in the fields of display materials and coating and printing apparatus materials related to water-based paints. An aluminum / CFRP composite material is obtained.

Claims (5)

  A hydrolytic condensate (A) composed of methyltrimethoxysilane, phenyltrimethoxysilane and glycidoxyalkyltrialkoxysilane compound and water (B) are blended, and the contact angle with respect to the aluminum alloy surface is 50 degrees or less. A primer composition for an aluminum alloy.   The glycidoxyalkyltrialkoxysilane compound is selected from 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, glycidoxyethyltrimethoxysilane, glycidoxyethyltriethoxysilane. The primer composition for aluminum alloys according to 1.   The said hydrolyzed condensate (A) is blended with 0.5 to 20 parts by weight of the water (B) and 1 to 200 parts by weight of the hydrophilic organic solvent (C) with respect to 100 parts by weight of the hydrolyzed condensate (A). The primer composition for aluminum alloys according to 2.   It is the adhesive member by which the said aluminum alloy and the carbon fiber reinforced plastic were compounded through the primer composition of any one of Claim 1 to 3, Comprising: The said aluminum alloy before and after salt water treatment, and a carbon fiber reinforcement An adhesive member having a ratio of adhesive strength to plastic of 90% or more.   The adhesive member according to claim 4, wherein the adhesive strength after the salt water treatment is 15 MPa or more.