JPS6153370A - Corrosion-proofing composition for chromium plating - Google Patents

Abstract

PURPOSE:To provide the titled composition composed of a thermosetting resin or prepolymer having a specific functional group and a reactive monomer compatible with the above resin or prepolymer, and effective to prevent the corrosion of a metallic material caused by the pinholes and cracks of chromium layer. CONSTITUTION:The objective composition is prepared by dissolving a thermosetting resin or prepolymer having >=2 allyl ester groups, (meth)acrylate groups, vinyl groups or epoxy groups in one molecule (e.g. polymer of diallyl phthalate, diallyl carbonate, etc.) in a reactive monomer (e.g. diallyl phthalate monomer) compatible with the above resin or prepolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Field of Application" The present invention relates to a corrosion-protective composition for chrome plating comprising a thermosetting resin or prepolymer having a specific functional group and one reactive monomer.

``Prior art'' A method of chromium plating on the surface of metal materials has been well known for the purpose of lowering the coefficient of friction on the surface of metal materials, improving surface hardness, and improving mechanical properties such as wear resistance. It is. Also.

Chrome-plated metal has excellent corrosion resistance and good appearance, and is suitable for use as a decorative material.

Chromium plating is usually carried out in a Sargent bath containing chromic anhydride as a main component, or in a silicate bath at a liquid temperature of 30 to 73°C, at a temperature of 30-/1. A method of electroplating at OA current density is often used. However, chrome plating has unavoidable defects due to hydrogen gas generated by electrolysis or residual stress in the coated chromium film.

For example, industrial chrome plating improves the mechanical properties of a metallic material, but typically produces a large number of pinholes (approximately A 0
00 id) and cracks (intersecting approximately J 00 MVcm) exist, through which outside air or moisture reaches the base of the metal material and causes rust, deteriorating the corrosion resistance.

Moreover, once rust occurs, it flows out onto the plating surface, and even if it is just a single spot of rust, it looks like most of it is rusted, which significantly impairs the appearance. To prevent rust, copper plating or nickel plating is applied before chrome plating.

A so-called decorative chrome plating method is then used to apply a thin layer of chrome plating. In this plating method, since the chromium layer is thin, the surface hardness is low and it is easily scratched, and when scratches occur, rust occurs from the scratched portion or the plating tends to peel off. It is possible to plate a thick layer of chromium on the copper plating layer or nickel plating layer to improve scratch resistance.
This method increases cost and is not suitable as a decorative plating material. In addition, since this method requires multi-layer plating of metals with different properties such as copper-lamin, nickel-chromium, copper-metal-chromium, etc., the plating may peel off after plating is completed or during use. happens.

In addition, in recent years, the demand for industrial chrome plating with mechanical properties and high corrosion resistance has increased dramatically, and a method of applying nickel plating with a thickness of IQ μm or more on the surface of a metal material and then applying chromium plating with a thickness of IQ μm or more has become available. However, the internal stress of the nickel plating layer and chromium plating layer is high in nickel 3. stbk
g/cr&, chrome to, o o o Wad)
Moreover, because the stress is too different, phenomena such as peeling and 7291 cracking are likely to occur in the plating layer during plating, resulting in a large number of non-defective products, and furthermore, the plating process becomes longer, resulting in higher costs. ``Problem to be solved by the invention'' Invention 41 solves the problem of preventing the chrome plating layer from forming in a special way even if pinholes and cracks occur, which are inevitable defects caused by hydrogen gas or residual stress during chrome plating. By performing surface treatment with a resin component, the resin component can penetrate into pinholes and cracks, filling the pinholes and cracks, blocking outside air and moisture from the base metal material, and ultimately preventing the occurrence of rust. With copper plating, nickel plating, etc., there is no need to prepare a copper or nickel undercoat, and it is possible to prevent the occurrence of peeling, blistering, cracking, etc. of the plating layer, solving all the conventional defects, and further shortening the plating process. The present invention was completed by discovering that it can be simplified.

That is, one object of the present invention is to provide a corrosion-resistant composition for chrome plating that can prevent corrosion of metal materials caused by pinholes and cracks in the chromium layer caused by chrome plating.

``Means for Solving the Problems'' One of the gist of the present invention is that thermosetting resins having at least three allyl ester groups, (methanoacrylate ester groups, vinyl groups or epoxy groups in one molecule) The present invention relates to a corrosion-resistant composition for chrome plating, which contains as main components a thermosetting resin or prepolymer and a reactive monomer that is compatible with the thermosetting resin or prepolymer.

Detailed Description of the Invention The thermosetting resin or prepolymer which is a component of the corrosion-resistant composition for chrome plating of the present invention has an allyl ester group, an acrylic ester group, a methacrylic ester group, a vinyl group or an epoxy group. It is necessary to have at least one free functional group in one molecule of the thermosetting resin or prepolymer (hereinafter simply referred to as resin), and it has good compatibility with the reactive monomers described below and can be easily dissolved. Any material may be used as long as it can be easily reacted and crosslinked with the monomer by heating, addition of a curing catalyst, irradiation with ultraviolet rays, etc., and cured. For example, allyl resin obtained by the reaction of diallyl phthalate, diallyl isophthalate, diallyl maleate, diallyl carbonate, etc., epoxy resin obtained by the reaction of shrimp halohydrin and bisphenol, Pton resin (hydrocarbon thermosetting resin) obtained by the reaction of butadiene and styrene, etc. Examples include so-called vinyl ester resins obtained by the reaction of polyester resins, epoxy resins, and unsaturated acids such as acrylic acid and methacrylic acid.

The resin is not limited to the resins specifically exemplified above, as long as it has at least one of the above-mentioned functional groups in its seven molecules.

The reactive monomer that is compatible with the thermosetting resin or prepolymer is not particularly limited as long as it is liquid at the handling temperature and dissolves the resin. Allyl compounds such as diallylacetone, diallyl carbinol, diallyl phthalate, diallyl isophthalate, diallyl maleate, triallyl cyanurate, triallyl phosphate, diallylbenzene phosphonate, allyl glycidyl ether, methyl acrylate, ethyl acrylate, butyl acrylate, 2 -Ethylhexyl acrylate.

Acrylic acid ester compounds such as ethylene glycol diacrylate, methyl methacrylate, x h) L/l
Tafrylate, butyl methacrylate.

Typical examples include methacrylic acid ester compounds such as hexyl methacrylate and cyclohexyl methacrylate, and styrene compounds such as styrene, methylstyrene, orthochlorostyrene, and styrene oxide.

At least one of these reactive monomers may be used in the present invention. Although the amount of these reactive monomers added to the resin is not particularly limited, it is blended in an appropriate ratio to the extent that one reactive monomer completely dissolves the resin and the resin and the reactive monomer are solidified in the desired time and by the desired curing method. Also, in consideration of application to the chrome plating layer surface and penetration into pinholes and cracks, when the resin is dissolved in the reactive monomer, it is less than s, ooo centipoise at 25°C, preferably JO to JOOO Preferably, it is in liquid form with a viscosity in the centiboise range.

In addition to the above-mentioned resin and reactive monomer, the corrosion-resistant composition of the present invention also contains a polymerization inhibitor such as hydroquinone and a weathering stabilizer for the purpose of preventing polymerization during storage and transportation of the composition.
Various additives such as ultraviolet absorbers and colorants may be included.

In order to treat the surface of chromium-plated metal with the corrosion-resistant composition of the present invention, first, the corrosion-resistant composition is added to the chromium layer surface of the chromium-plated metal, and if necessary, a curing catalyst and a curing accelerator are added. After that, apply by brushing, spraying, dipping, pressure infiltration, vacuum pressure, etc. to penetrate the anticorrosion composition into the pinholes or cracks that occur in the chrome plating layer, leave it at room temperature, irradiate it with ultraviolet rays, and heat it. The anticorrosive composition is solidified by a method such as the following.

Curing catalysts are usually peroxides for unsaturated substances and amines for epoxies; for example, tert-butyl peroxybenzoate, benzoyl peroxide, diethylenetriamine, triethylenetetramine, polyamide are used as heat curing catalysts. Further, examples of cold curing catalysts for unsaturated substances include methyl ethyl ketone peroxide, acetylacetone peroxide, dicumyl peroxide, etc., and these catalysts are used together with curing accelerators such as cobalt heptathenate. is preferable. The amount of curing catalyst used is 0.2 to 0.2 J to the anticorrosion composition.
, ON amount range is appropriate. Further, it is preferable to use the same equivalent amount of epoxy and amine.

The chrome-plated metal surface treatment will be explained in more detail. For example, chrome-plated metal materials with a thickness of 3 μm or more can be heated in a heating furnace! Preheat at a temperature of 2□±1O°C for 73 to 30 minutes to remove hydrogen gas generated during electroplating or moisture in cracks. Then the temperature of the metal material is 60
After air-cooling to ±IQ°C, a corrosion-resistant composition prepared in advance by adding a curing catalyst is applied to the chrome plating layer, penetrated into the pinholes and cracks in the chrome layer, and the metal material is heated in a heating furnace with iro ± Cure the anti-corrosion composition by heating at a temperature of IQ°C for 120 minutes or more - If the rimmeggi layer has more pinholes or cracks than normal metal materials,
The first layer of anti-corrosion composition begging for it? 120± after application and penetration
Heating at lθ°C for 30 minutes, applying the anti-corrosion composition again before the material temperature drops /j;
Reheat for 20 minutes. In addition, hardened stainless steel and high carbon steel (8 qoc or more) that require removal of hydrogen embrittlement have a hardness of ROII.
Materials with a temperature of O or above are heated at iqo±l1° C. and above Igo minutes to remove hydrogen embrittlement, and then the anticorrosion composition is applied and cured according to the above-mentioned procedure.

After hardening, the metal material has a thin resin film of anti-corrosion composition formed on the surface of the chromium layer. Polish to remove peeling.

``Effects of the Invention'' According to the present invention, a corrosion-resistant composition consisting of a thermosetting resin or prepolymer having a specific functional group and a reactive hexamer can be applied to pinholes and cracks in the chromium layer that are inevitable in chrome plating. It penetrates and solidifies in the pinholes and cracks, completely filling the pinholes and cracks in the chrome layer, completely shielding the base metal material from outside air and moisture, and preventing rust from occurring for a long time. . In addition, the conventional structure of preparing a base using copper plating and nickel plating to prevent rust is no longer necessary, and the plating process for metal materials is greatly shortened and simplified. No more processing.

It also helps prevent pollution. Furthermore, since there is no base layer with different residual stresses such as nickel and copper, peeling of the plating layer can be avoided.
Phenomena such as blistering and cracking are completely eliminated, and the value of industrial use is great.

"Examples" The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 A corrosion protection composition was prepared by dissolving 30 parts by weight of diallyl phthalate resin in 70 parts by weight of diallyl phthalate monomer. The viscosity at 25°C was 7 IOCp.

When used, tert-butyl peroxydipenzoate was added.

Separately, apply 2 s of chromic anhydride to the surface of multiple low carbon steel (Stsc) metal materials with an outer diameter of 1, S 200 mm and a length of 200 mm.
o g/l, sulfuric acid, j,! Il/l - trivalent chromium Trivalent chromium 3/i plating condition ssr: chromium layer thickness 2 at current density oA/square decimal
It was chromium-plated to a thickness of 0 μm to obtain a chrome-plated metal material.

Chrome plated metal material Y/Co 117'c. After preheating for 20 minutes, the anticorrosion composition was cooled in air to 0°C, and then the anticorrosion composition described above was applied with a brush to penetrate into the pinholes and cracks present in the chrome plating layer, and then heated in a heating furnace at 0°C for an hour. The anticorrosion composition was allowed to solidify. In order to remove the anticorrosive composition adhered to the surface of the chromium layer, back polishing was performed to expose the chromium layer, which was then used as a sample for corrosion resistance testing.

The corrosion resistance test method was a 2110-hour continuous salt spray test based on J.S. Hgr02-19g-.

For comparison, samples to which no anticorrosive composition was applied were also tested. The results are shown in Table 1.

As is clear from Table 1, the chrome plating surface treated with the anti-corrosion composition for chrome plating has significantly fewer corrosion holes than the untreated one, showing an extremely excellent rust prevention effect. I understand that.

Example 7 7% allyl glycidyl ether was added to the epi-bis type resin of low polymerization degree cn 2) at /'400 to prepare a sample for corrosion resistance test, and a corrosion test was conducted. The results are also listed in Table 1.

Example 3 Dieboxide was synthesized from a comol of shrimp chlorohydrin and 1 mole of bisphenol A by a dehydrochloric acid reaction, and two moles of acrylic acid were further added to obtain a vinyl ester.

The same weight of styrene monomer was added to the vinyl ester and diluted to prepare a corrosion-resistant composition. Tertiary butyl peroxybenzoate was added when used.

A sample for a corrosion resistance test was prepared in the same manner as in Example 1, and then a corrosion test was conducted. The results are shown in Table 1.

Claims (6)

[Claims] (1) A thermosetting resin or prepolymer having at least two allyl ester groups, (meth)acrylic acid ester groups, vinyl groups, or epoxy groups in one molecule, and a thermosetting resin or prepolymer that is compatible with these thermosetting resins or prepolymers. A corrosion-resistant composition for chrome plating, which mainly contains a certain reactive monomer. (2) The anticorrosion composition for chrome plating according to claim 1, wherein the thermosetting resin or prepolymer is a polymer of diallyl phthalate or diallyl carbonate. (3) The corrosion-resistant composition for chrome plating according to claim 1, wherein the thermosetting resin or prepolymer is an epichlorohydrin-bisphenol A copolymer. (4) Claim 1, wherein the thermosetting resin or prepolymer is a vinyl ester resin obtained by reacting (meth)acrylic acid with an epoxy resin or prepolymer obtained by the reaction of epichlorohydrin and bisphenol A. Anticorrosion composition for chrome plating. (5) The corrosion-resistant composition for chrome plating according to claim 1, wherein the thermosetting resin or prepolymer is a butadiene-styrene copolymer. (6) The anticorrosive composition for chrome plating according to claim 1, wherein the reactive monomer is at least one selected from allyl compounds, acrylic ester compounds, methacrylic ester compounds, and styrene compounds.