JPS61182940A - Manufacturing method of anti-corrosion metal products - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a metal product having a silicone resin-based anticorrosive protective coating formed on its surface.

(Prior Art) Conventionally, chromate treatment has been commonly used as a rust prevention treatment and coating base treatment for metal products, such as plated steel plates. However, its performance is only at the level of so-called temporary rust prevention.

In recent years, many new anti-corrosion protective coatings have been proposed to improve the corrosion resistance of steel plates and the like. parable 55-629
No. 71, No. 57-105344, etc., propose an organic/inorganic composite film comprising colloidal silica and a water-soluble or water-dispersible organic resin.

However, in all of the above films, since the organic resin is hydrophilic, it cannot be said that they have sufficient corrosion resistance.

(Problems to be Solved by the Invention) An object of the present invention is to provide a metal product having a novel anti-corrosion protective film that has excellent water resistance and corrosion resistance as a rust preventive treatment for metal products and as a base treatment for painting. .

(Means for Solving the Problems) The present inventors have developed a particularly highly reactive alkoxysilane-containing coating solution, specifically, +1) a combination of an amino group-containing alkoxysilane and an aliphatic unsaturated bond-containing epoxy compound. After applying a coating solution containing either the reaction product or (2) a mixture of an aliphatic unsaturated bond-containing alkoxysilane and a silicate ester as a coating component to the surface of a metal product, the coating film is cured by heating. The inventors have discovered that the cured film obtained by this method can achieve the above objectives, and that even better physical properties of the coating film can be obtained by combining both (1) and (2) above, and have completed the present invention. Ta.

Here, the present invention provides (a reaction product of an alkoxysilane containing an amino group or a partial hydrolyzate thereof and an epoxy compound containing an aliphatic unsaturated bond, or a partial hydrolyzate of this reaction product as a coating film component) Coating solution containing a mixture of an aliphatic unsaturated bond-containing alkoxysilane or a partial hydrolyzate thereof and a silicate ester or a partial hydrolyzate thereof, or a co-partial hydrolyzate of the mixture as a coating component. liquid,
and (Cl amino group-containing alkoxysilane or a partial hydrolyzate thereof and an aliphatic unsaturated bond-containing epoxy compound, with or without reacting these or a partial hydrolyzate thereof, and an aliphatic unsaturated bond-containing epoxy compound). From the group consisting of a reaction mixture formed by mixing an alkoxysilane or a partial hydrolyzate thereof with a silicate ester or a partial hydrolyzate thereof, or a coating liquid containing a co-partial hydrolyzate of the reaction mixture as a coating component. The metal product further includes a hardened film formed on the surface by applying and baking a selected coating liquid.

According to one aspect of the present invention, the metal product further has a chromate film as a base layer in addition to the above-mentioned hardened film.

(Function) The amino group-containing alkoxysilane used in the present invention may contain both an amine having an active hydrogen in its molecule, that is, a -class or secondary amine structure, and a hydrolyzable silane structure. Any compound may be used, and is not particularly limited to a specific compound.

A typical commercially produced, readily available, and practical example is 3-aminopropyltriethoxysilane. Another example is 3-(n-aminoethyl)aminopropyltrimethoxysilane.

The alkoxysilane may be partially hydrolyzed in advance, as is usually done when using a silane coupling agent, that is, a partially hydrolyzed product made into an oligomer by partial dehydration condensation may be used.

On the other hand, the aliphatic unsaturated bond-containing epoxy compound to be reacted with this alkoxysilane is a compound in which an aliphatic unsaturated bond and an epoxy group exist in the same molecule, such as a vinyl group, vinylidene group, acryloxy group, or methacryloxy group. If so, it is possible to achieve the purpose of the present invention. Representative examples include glycidyl methacrylate and glycidyl acrylate.

According to the present invention, the above-mentioned amino group-containing alkoxysilane and the aliphatic unsaturated bond-containing epoxy compound are reacted in advance to form a coating liquid. Through this reaction, a compound containing functional groups such as an aliphatic unsaturated bond, a hydroxyl group, an amino group (or imino group), and an alkoxy group in the same molecule is produced by the epoxy ring-opening reaction shown in the following formula.

OOH Therefore, when a coating solution containing this reaction product is applied and cured by heating, the high-order cross-linking of various highly reactive functional groups results in film-forming properties, adhesion, high hardness, and water resistance. The cured film of the present invention exhibits excellent characteristics such as hardness and rust prevention.

A partially hydrolyzed product obtained by partially hydrolyzing this reaction product also functions effectively as a coating film component.

When preparing a coating liquid by reacting both of the above components, from the viewpoints of prevention of side reactions, ease of reaction control, ease of handling due to reduced viscosity, and improvement of stability against changes over time,
It is recommended to use organic solvents that can dissolve both the raw materials and the desired reactants. Since the amino group-containing alkoxysilane and the aliphatic unsaturated bond-containing epoxy compound have extremely high reactivity, it is possible to gently advance the reaction by, for example, adding one of the reaction components dropwise under moderate heating. can.

According to the second aspect of the present invention, the same excellent coating performance as that of the cured coating formed from the coating solution containing the reaction product of the above amino group-containing alkoxysilane and the aliphatic unsaturated bond-containing epoxy compound, It can also be obtained from a coating solution containing a mixture of an aliphatic unsaturated bond-containing alkoxysilane and a silicate ester.

The aliphatic unsaturated bond-containing alkoxysilane used in the case of the second 8th case is particularly suitable if it has an aliphatic unsaturated bond and a hydrolyzable silane structure as described above in the same molecule. Although not limited to, commercially available silane cuffing agents are commercially available as readily available and practical agents, and partially hydrolyzed products thereof can also be used. Representative examples thereof include 3-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane.

Examples of the silicic acid ester to be mixed with the aliphatic unsaturated bond-containing alkoxysilane include monoalkyltrialkoxysilane, phenyltrialkoxysilane, and tetraalkoxysilane, or partial hydrolysates of these esters. Any of these can be used, but a typical example is tetraethoxysilane.

Before use, it is desirable to dilute this coating solution consisting of a mixture of an aliphatic unsaturated bond-containing alkoxysilane and a silicate ester with a volatile organic solvent in order to make the coating easy and uniform. It is also possible to mix both components in the presence of , and there is no problem.Also, it is also possible to use a partial hydrolyzate for one or both of these components, or a partial hydrolyzate can be used for either or both of these components, or after mixing both components, A copartial hydrolyzate may be obtained by hydrolysis. Similar to the first coating solution, the coating solution of this second embodiment also has many highly reactive functional groups in its coating film components, so it is capable of high-order crosslinking, and has similar excellent properties. It is possible to demonstrate the performance of a cured film.

Two types of coating liquids were produced as described above, namely, ta) a coating liquid whose coating film component is a reaction product of an amino group-containing alkoxysilane and an aliphatic unsaturated bond-containing epoxy compound, and (b) a coating liquid containing a fatty acid. It is also possible to use a mixture of both groups of unsaturated bond-containing silanes and silicate esters as a coating component. Performance such as alkali resistance of the membrane can be improved.

In addition, in preparing the mixture of the two types of coating liquids (al and (b), it is only necessary to prepare the coating liquids (a) and (bl) separately as described above and then mix them together. For example, an aliphatic unsaturated bond-containing epoxy compound may be added dropwise to a system in which an aliphatic unsaturated bond-containing alkoxysilane, a silicate ester, and an amino group-containing alkoxysilane are present; group unsaturated bond-containing alkoxysilane,
A method may also be adopted in which an amino group-containing alkoxysilane is dropped into a system in which a silicate ester and an aliphatic unsaturated bond-containing epoxy compound are present. That is, in the case of a mixture containing these four components, there is no need to react the amino group-containing alkoxysilane and the unsaturated epoxy compound in advance;
The mixture may be reacted after mixing the four components. Regardless of which method is adopted, the conditions for reacting the amino group-containing alkoxysilane and the aliphatic unsaturated bond-containing epoxy compound and the type of solvent that can be used are as described above.

Each of the components used in the present invention, such as alkoxysilane, has the ability to form a coating film even when used alone, so the ratio of their use can be varied over a wide range.

In any case, in the coating liquid used in the present invention prepared as described above, the hydrolyzable silane portion undergoes hydrolysis and dehydration condensation due to moisture in the air during the coating and heat curing process. As a result, it changes into polysiloxane and becomes a constituent component of the coating film. However, in order to more reliably cause this condensation reaction, it is necessary to partially hydrolyze at least one of each hydrolyzable raw material, that is, an alkoxysilane containing an amino group, an alkoxysilane containing an aliphatic unsaturated bond, or a silicate ester. It is preferable to apply the mixture after co-partial hydrolysis after mixing the components.

A catalyst can also be used for this partial hydrolysis.

As the catalyst that can be used, alkaline ones are preferable in consideration of the effect on rust prevention, but acidic ones can also be used. Partial hydrolysis or partial cohydrolysis can proceed gradually under moderate heating while using a small amount of water and preferably a catalyst.

The coating liquid used in the present invention may further contain additives such as a curing accelerating catalyst and a polymerization inhibitor for suppressing polymerization of aliphatic unsaturated bonds.

Furthermore, in order to improve processability, organic resins such as epoxy resins, acrylic resins, polyester resins, and urethane resins, antirust pigments, inorganic fillers, lubricants, and the like can be added.

The present invention can be applied to various metal products coated with anticorrosion coatings. For example, galvanized steel or zinc-iron,
The hardened coating of the present invention can be applied to zinc alloy-plated steel sheets such as zinc-nickel and zinc-aluminum, aluminum-plated steel sheets, composite plated steel sheets with multilayers of these platings, and metal products such as aluminum, stainless steel, copper, and brass. can be provided.

Application of the coating solution according to the present invention to metal products can be carried out by conventional methods such as dipping, roll coating, and spray painting. The amount of coating film to be applied is 0.1g/to obtain sufficient corrosion resistance.
It is preferable to set it to m or more. The coating film is baked and cured by heating in a conventional manner. Heating temperature is generally 150-350
'C1 heating time is about 30 seconds to 60 minutes.

When a high degree of corrosion resistance is desired, the surface of the metal product is subjected to chromate treatment as a base, and the above coating liquid is applied thereon. For chromate treatment, ordinary reactive or paint-on chromate is applied.

The invention will now be illustrated by examples. In the examples, parts and percentages are by weight unless otherwise specified.

Add isopropyl alcohol (abbreviated as IPA) to the go part.
- 10 parts of aminopropyltriethoxysilane (abbreviated as APS-E) was dissolved, and 10 parts of glycidyl methacrylate (abbreviated as GM 8) was added dropwise to the resulting solution over 3 hours at 80°C to react. A coating liquid A was obtained by aging at a temperature for 1 hour.

1 Okudan 3-methacryloxypropyltrimethoxysilane (MO
15 parts of tetraethoxysilane (abbreviated as PS-M), 15 parts of tetraethoxysilane (ES
-28) and 40 parts of IPA,
A mixed solution consisting of 0.05 part of 29% aqueous ammonia, 5 parts of water, and 35 parts of IPA was added dropwise to this mixture over 5 hours at 60'C, and further aged at the same temperature for 3 hours to obtain coating liquid B. Ta.

Jofu Motan IPA 95 parts, water 1 part, MOPS-M 3 parts, GMA
10 parts, and a partial hydrolyzate of ethyl silicate (
[! 5-40) and add APS-E to this.
Coating liquid C was obtained by stirring 10 parts at 6°.

7 parts of 3-(n-aminoethyl)aminopropyltrimethoxysilane (abbreviated as AAS-M) was dissolved in 680 parts of P, and 13 parts of GMA was added dropwise to this solution at 80°C over 3 hours. The mixture was reacted and further aged for 1 hour at the same temperature to obtain an aminosilane compound. Separately, 3 parts of vinyltrimethoxysilane (abbreviated as VTS-M), ES-403
A mixture of 1 part of water, 1 part of 0.05N HCI solution, and 5 parts of IPA was added dropwise to this mixture over 3 hours at 60°C, and the mixture was further heated at the same temperature for 2 hours. It was reacted and aged. This liquid and the aminosilane-containing liquid obtained above were mixed to obtain a coating liquid.

The compositions of the above coating solutions A to D are summarized in Table 1 below (numbers in parentheses are parts by weight).

Table 1 Next, after degreasing an electrogalvanized steel sheet with a thickness of 0.8 fi, a zinc-nickel alloy electroplated steel sheet (coating weight is 20 g/rrf on each side), and an aluminum plate with the same thickness, The coating solution was applied by dip coating so that the dry coating weight was Ig/rrF, and the coating was cured by baking in an oven at 250° C. for 10 minutes.

When performing chromate treatment, before applying the above coating liquid, apply a chromate treatment liquid (Kansai Paint Co., Ltd., Acomoto C) so that the amount of chromium deposited is approximately 100I100I, and A chromate film was formed by baking for 10 minutes.

Each of the obtained test pieces was subjected to a corrosion resistance test (salt spray test) and an alkali resistance test to examine the performance of the cured film formed according to the present invention. The salt spray test was conducted for 100 hours, and in some cases for 400 hours. The alkali resistance test was evaluated by immersing the test piece in an aqueous solution of Na OI with a pH of 13 at 60° C. for 3 minutes.

For comparison, test pieces on which only a chromate film was formed and a test piece on which a cured film of ethyl silicate (ES-40) was formed were also tested in the same manner.

The results are shown in Table 2 below. As is clear from Table 2,
The test piece according to the present invention had very good corrosion resistance and alkali resistance.

Table 2: Alkali resistance: Good: No damage to the film, Medium: Partial damage to the film, Poor: Some peeling of the film (Effects of the invention) Metal products having a hardened film according to the present invention have good corrosion resistance as is. Therefore, it is useful as a general corrosion-resistant metal product. Furthermore, since this cured film has good adhesion to electrodeposition coatings and other coating films, it is suitable as a coating base, especially as a base for electrodeposition coating. In the case of painting, it is often applied after an alkali degreasing process, but the cured film formed by the present invention has very good alkali resistance, so it also has the advantage that the film is less likely to be damaged during alkali degreasing. be. Furthermore, the adhesion between the cured film and the metal product is particularly poor, making it difficult for the film to be damaged even when processed, providing sufficient performance and offering excellent stain resistance such as fingerprint resistance. There is.

Claims (2)

[Claims] (1) (a) A reaction product of an amino group-containing alkoxysilane or its partial hydrolyzate and an aliphatic unsaturated bond-containing epoxy compound, or a coating liquid containing a partial hydrolyzate of this reaction product as a coating component. , (b) a mixture of an aliphatic unsaturated bond-containing alkoxysilane or a partial hydrolyzate thereof and a silicate ester or a partial hydrolyzate thereof, or a coating liquid containing a copartial hydrolyzate of the mixture as a coating component; and (c) amino group-containing alkoxysilane or a partial hydrolyzate thereof and an aliphatic unsaturated bond-containing epoxy compound, with or without reacting these or a partial hydrolyzate thereof, and an aliphatic unsaturated bond. A group consisting of a reaction mixture formed by mixing a containing alkoxysilane or a partial hydrolyzate thereof with a silicate ester or a partial hydrolyzate thereof, or a coating liquid containing a co-partial hydrolyzate of the reaction mixture as a coating film component. A metal product characterized by having a hardened film on its surface formed by applying and baking a coating liquid selected from the following. (2) The metal product according to claim 1, further comprising a chromate film for base treatment as a lower layer of the hardened film.