JPH0128832B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition for preventing metal rust. More specifically, it relates to a rust-preventive composition that exists stably at room temperature, forms an effective film when applied to a metal surface by moisture present in the atmosphere or by slight heating, and exhibits good rust-preventive properties. In particular, the present invention relates to a rust-preventing composition suitable for copper or copper alloys such as copper, silver, German silver, and metals coated with various chromate coatings such as yellow, black, and green. Traditionally, metal rust prevention treatment involves applying various paints, such as solvent-based, water-based, or powdered thermosetting paints such as epoxy, alkyd, polyester, acrylic, and urethane, and baking them, and polyolefin paints. , a method for welding and coating thermoplastic resins such as polyamide and polyester,
Methods of anointing with various oils (mineral oil, animal oil, vegetable oil), plating with metals and metal salts, etc.
Methods such as surface treatment are used. Among these, thermosetting or thermoplastic resin paints cannot exhibit sufficient rust prevention properties unless the coating is applied thickly (10 to 2000 μm), even in systems with added anticorrosion pigments such as chromate or phosphate paints. Also, since high temperatures are required for baking and welding the paint, damage to the base material,
There are disadvantages such as heat energy loss. In addition, the method of applying oil to metal substrates is only used for temporary rust prevention purposes, and under the conditions in which the substrate is originally used, the oil that is "dirt" is usually degreased. be. In addition, the surface treatment method is far inferior in rust prevention compared to the case of painting with the above-mentioned paint, and it is usually used as a base for painting with paint. Further, even in the case of metal plating, for example, when exposed to high temperatures of 50 to 80° C. or higher, such as chromate coatings, the coatings may denature and lose their anti-corrosion performance, and various other problems have occurred. The present inventors have completed the present invention as a result of intensive studies to overcome the above problems. That is, the present invention relates to a metal rust preventive composition comprising an organosilicon compound having an aminoalkyl group and an alkoxy group (hereinafter referred to as component A) and a compound having an oxirane ring (hereinafter referred to as component B). be. The composition of the present invention can be applied to a wide range of substrates, but its effects are particularly remarkable on copper, copper alloys, and metals such as iron and zinc coated with various chromate coatings. The copper alloys mentioned here include, for example, Shinchiyu (alloy of 67 copper and 33 zinc), German silver (50 copper,
A chromate film is a surface film that is produced by immersing a metal in a treatment solution whose main components are chromic acid or chromates and mineral acids.For example, XCr _{2O3 ,}
Refers to a film consisting of YCrO ₃ and ZH ₂ O. The advantages that arise when the composition of the present invention is applied to metal substrates are as follows. (In the following, the metal base material means the metal itself and the metal that has been subjected to surface treatment such as plating.) 1. The metal base material is immersed in a composition, preferably in a composition solution diluted with a solvent, and then air-dried. Alternatively, a coating film can be formed by only slight heating, and good rust prevention properties can be imparted very easily. 2. The coating film to be formed on the metal substrate exhibits good rust prevention properties even if it has an extremely thin thickness of 1 to 10 μm.
Various troubles in the work and process due to the increase in the thickness of the base material due to the coating film do not occur. 3. The coating film is transparent and does not color the base material. 4. It is advantageous in terms of environmental hygiene because it does not require the addition of toxic anti-rust pigments. Specific examples of the organosilicon compound which is component A of the composition of the present invention include aminoalkyl groups such as aminomethyltriethoxysilane, γ-aminopropyltriethoxysilane, and γ-aminoisobutyltrimethoxysilane. Aminoalkyltrialkoxysilane with 3 alkoxy groups; N-(β-aminoethyl)aminomethyltrimethoxysilane, N-(β-aminoethyl)aminomethyltriethoxysilane, N-(β-aminoethyl)- N-(aminoalkyl)aminoalkyltrialkoxysilane having an N-(aminoalkyl)aminoalkyl group and three alkoxy groups such as γ-aminopropyltrimethoxysilane; aminomethylmethyldiethoxysilane, γ-
Aminoalkylalkyldialkoxysilane having an aminoalkyl group and two alkoxy groups such as aminopropylmethyldiethoxysilane; N-
(aminoalkyl)N-(β-aminoethyl)-γ having an aminoalkyl group and two alkoxy groups
-aminopropylmethyldimethoxysilane, etc., and those having two or more alkoxy groups are preferred for the present invention in order to improve rust prevention properties. In addition, component B, which is another main component, is a compound having an oxirane ring, and is a generally known epoxy resin, that is, bisphenol A and F type epoxy resin. X:

[Formula] or

[Formula] or H Y: alkyl group or H glycidylamine type epoxy resin, for example, X ₂ N-R ¹ -NX ₂ ,

【formula】 X:

[Formula] R ¹ , R ² : alkylene group, aralkylene group,
Cycloalkylene group, etc. Novolac type epoxy resin, e.g. X:

[Formula] R: An alkyl group, an aralkyl group, etc. can be applied. Moreover, compounds having an oxirane ring other than the above-mentioned epoxy resins can also be used. Compounds having an oxirane ring other than epoxy resins include organosilicon compounds having an oxirane ring and an alkoxy group. Examples of such compounds include glycidoxyalkyltrialkoxysilanes such as γ-glycidoxypropyltrimethoxysilane, and glycidoxyalkylalkyldialkoxysilanes such as γ-glycidoxypropylmethyldimethoxysilane. Preferable compounds for use in the present invention are organosilicon compounds having an oxirane ring and an alkoxy group, particularly those having two or more alkoxy groups. The blending ratio of component A and component B in the present invention is preferably 0.05 to 1 of component A to 1 of component A, more preferably 0.2 to 1 of component B based on the molar ratio based on average molecular weight. It is 0.9.
If the amount of component B is less than 0.05 mole per mole of component A, the composition is stable, but effective bonding between the oxirane ring and the amino group is not substantially performed, making it difficult to apply it to metal substrates. Due to the solution viscosity being too low and the film forming ability being low, it is difficult to obtain film properties and thickness that should exhibit good rust prevention properties. In addition, if the B component exceeds 1 mole, the composition is unstable and tends to thicken or gel, and the resulting coating lacks toughness and may be damaged by external forces. Rust prevention becomes inferior due to reasons such as easy rusting. Although good results can be obtained with the composition of the present invention using only the A component and the B component, suitable coating properties and
In order to obtain stability, the composition is preferably diluted with a solvent. A wide range of solvents can be used, including non-polar and polar solvents, such as benzene, toluene, xylene, cyclohexane, acetone, methyl ethyl ketone,
They can be appropriately selected from methanol, ethanol, isopropanol, ethyl ether, cellosolve, methyl cellosolve, etc. and used alone or in combination. When a solvent is used, the total concentration of component A and component B in the composition is preferably 1 to 30% by weight. Furthermore, it is also possible to add other components to the composition of the present invention; for example, an amine-based or phosphate-based rust preventive may be used in combination within a range that does not cause gelling or thickening phenomena; , it is possible to add a trace amount of water etc. for the purpose of increasing the molecular weight through siloxane bonding. When the composition of the present invention is coated on a metal substrate,
The film is formed by bonding between the oxirane ring and the amino group.
It is thought that this is done by siloxane bonding due to dealcoholization of an alkoxy group-containing organosilicon compound, etc., and a good film is formed by slight heating or moisture absorption of the coating film, respectively, so it is necessary to heat the metal substrate to a particularly high temperature. These steps are unnecessary. As described above, the composition of the present invention can improve the drawbacks of chromate coatings and exhibit excellent rust prevention performance. That is, chromate coatings are usually widely used as protective plating for most metals such as zinc, cadmium, aluminum, copper, etc., and exhibit effective corrosion resistance as well as aesthetic appearance, but their biggest drawback is that their corrosion resistance deteriorates when heated. It has been confirmed through many experiments that when heated to a temperature of 80° C. or higher, the corrosion resistance in the salt spray test (JIS-Z-2371) is virtually the same as without the chromate coating. Reasons for this include the occurrence of cracks due to dehydration of the chromate film due to heating, and the change of soluble chromium to insoluble, and so far, no effective rust prevention treatment has been developed for such cases. Ta. There are many demands for applying chromate-treated metals to heated parts or heat-processing them to create new products, and many efforts have been made to overcome the above-mentioned problems in such cases. When applying the composition of the present invention,
Whether it is applied to a chromate film that has no thermal history and heated, or applied to a chromate film that has been destroyed by heating, it can exhibit rust prevention that is equivalent to or better than before heating. This is surprising and is a major feature of the present invention. According to the invention, copper and copper alloys,
It is possible to easily perform rust prevention treatment on various chromate-plated metal base materials, and the rust prevention properties thereof are greatly improved.Furthermore, the metal base materials treated with the composition of the present invention can be heated to improve corrosion resistance. The present invention greatly contributes to industry in that it can be applied to various parts without considering deterioration. Hereinafter, the present invention will be explained in detail by giving Examples and Comparative Examples. Example 1 and Comparative Example 1 γ-aminopropyltriethoxysilane (molecular weight 221) 11.05 g (0.05 mol), bisphenol A
Type epoxy resin Epicoat 828 (manufactured by Yuka Ciel Epoxy Co., Ltd., average molecular weight 335) 3.35 g (0.01 mol) was mixed with toluene and methyl ethyl ketone in a 1:1 (weight ratio)
Diluted with 129.6g of mixed solvent to obtain a component concentration of 10
A composition was made that was % by weight. A 25 mm x 100 mm, 3 mm thick copper plate and Shinchiyu board (both manufactured by Nippon Test Panel Co., Ltd.) were immersed in the above composition, air-dried, and then heated at 50°C for 1 hour.
A rust-preventive coating film with an average thickness of 3 to 5 μm was formed on the metal surface. The above-mentioned coated test piece and a test piece simply subjected to degreasing treatment as Comparative Example 1 were evaluated using a salt spray test (JIS-Z-2371), and the results shown in Table 1 were obtained. It was confirmed that there was a large difference in corrosion resistance between the composition of the present invention and conventional products.

[Table] Examples 2 to 4, Comparative Examples 2 to 3 0.05 mol of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and 0.015 mol of γ-glycidoxypropyltrimethoxysilane were added to toluene and methyl cellosolve. A composition was prepared by diluting the component concentration to 10% by weight with a 1:1 (weight ratio) mixed solvent, and a test piece was prepared with a size of 25 mm x 100 mm and a thickness of 0.5 mm.
An iron plate (SPCC-SD) was plated with alkaline zinc (thickness 15 μm), washed with water, immersed in 3% nitric acid solution for 15 seconds, washed again with water, and then treated with sodium dichromate, chromic anhydride, nitric acid, and sulfuric acid. The above galvanized steel sheet was placed in a chromate treatment solution containing 150 g, 50 g, 50 ml, and 10 ml in each aqueous solution at room temperature.
A chromate-treated galvanized steel sheet obtained by dipping for seconds, leaving in the air for 15 seconds, washing with water, and air drying was used, and a film was formed by dipping it in the above composition according to the treatment procedure shown in Table 2 (Example 2, 3, and 4) and those that were not immersed (Comparative Examples 2 and 3) were subjected to a salt spray test (JIS-Z-2371) and evaluated. The results are shown in Table 2.

[Table] Example 5 N as aminoalkyl polyhydric alkoxysilane
-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane 0.05 mol was used, but the same test as in Example-2 was conducted using a rust preventive liquid composition having the same composition as in Example-2. As a result, almost no rust was observed after 240 hours of salt water spraying. Example 6 and Comparative Example 4 The rust preventive liquid compositions shown in Table 3, namely those using the composition of the present invention (Example 6) and those using copolymerized nylon (Comparative Example 4) were used. As a test piece, a chromate-treated galvanized steel round bar (diameter
10 mm, length 100 mm) was heated at 200°C for 60 minutes and cooled, then immersed in the antirust liquid composition shown in Table 3, air-dried, and then subjected to a salt spray test (JIS-Z-2371).
The results of the evaluation are shown in Table 3.

[Table] Examples 7 to 9 and Comparative Examples 5 to 7 Using the same composition as in Example 2, commercially available zinc chromate bolts coated with yellow chromate, green chromate, and black chromate were coated as shown in Table 4. Table 4 shows the results of the salt spray test conducted on the samples treated with the composition of the present invention (Examples 7 to 9) and the untreated samples (Comparative Examples 5 to 7). Shows excellent effects on various heated chromate coatings.

【table】

Claims (1)

[Claims] 1. A metal rust prevention composition comprising an organosilicon compound having an aminoalkyl group and an alkoxy group and a compound having an oxirane ring.