JPS6121575B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rust-preventing coating composition.

Rust-preventing paints currently in use, including wash primers, contain lead oxide, lead sulfate, and lead sulfate as rust-preventing pigments.
Paints contain heavy metals such as chromates, and their exhaust and wastewater are considered to be one of the causes of pollution. Self-polishing ship bottom paints, which have recently attracted particular attention, contain heavy metals as anti-corrosion pigments and cause marine pollution.

In addition to the above-mentioned paints, there are also paints that contain less toxic metals such as non-heavy metals such as zinc, aluminum, stainless steel powder, or scaly iron oxide as anti-rust pigments, but in these cases, they contain large amounts of such metals. It has the disadvantage that it is difficult to coat because of the coating, or it cannot be coated in a thin film, resulting in a large amount of paint being used.

An object of the present invention is to provide a coating material that has extremely excellent antirust properties without using not only highly toxic heavy metals but also lowly toxic metals.

Another object of the present invention is to provide a paint that can be applied to a thin film of about 5 to 10 microns and has extremely excellent antirust properties.

The present invention comprises 100 parts by weight of an epoxy resin having an epoxy equivalent of 900 to 3000, 5 to 40 parts by weight of a monovalent or divalent phenol resin, and 2-imidazolyl having hydrogen or an alkyl group having 1 to 4 carbon atoms as a substituent at the 2-position. A cocondensate consisting of 0.5 to 6 parts by weight of a group-containing compound is mixed with 0.3 parts of at least one chelating reagent selected from aminophenol and 8-oxyquinoline that binds with metal ions to form a chelate compound.
It relates to a rust-preventing coating composition characterized in that it contains ~5 parts by weight.

The present invention will be explained below. Epoxy resin itself has good adhesion to metal surfaces, and
It also has good chemical resistance to alkalis and other substances, and has excellent rust prevention properties. In the present invention, among such epoxy resins, those having an epoxy equivalent of 900 to 3000 are particularly preferably used. Specifically Epicote 1004, 1007, 1009
(manufactured by Ciel Kagaku Co., Ltd.), etc. can be exemplified.

In the present invention, the phenolic resin includes monovalent or divalent phenols, such as phenol,
Resins obtained from cresol, xylenol, catechol, resorcinol, etc. and aldehydes such as formaldehyde, acetaldehyde, furfural, etc., and their modified resins are used. In particular, divalent phenols are used in natural lacquer, etc. For example, alkylcatechols with linked chains bond with metals to form chelate compounds and have a strong effect of protecting metal surfaces. It is preferable to use 5 to 40 parts of such phenolic resin based on 100 parts (by weight, the same applies hereinafter) of the epoxy resin.

Next, as a compound containing a 2-imidazolyl group, hydrogen is added as a substituent at the 2-position of imidazole, and the number of carbon atoms is 1.
Compounds having ~12 alkyl, aryl groups can be used. Preferred specific examples include imidazole, 2-methylimidazole, 2-butylimidazole, 2-undecylimidazole, and 2-phenylimidazole.
Such a 2-imidazolyl group-containing compound forms a metal chelate by itself and acts as a curing agent for the epoxy resin, and is usually used in an amount of 0.5 to 6 parts by weight per 100 parts of the epoxy resin.

In the present invention, the inherent excellent properties of epoxy resin are utilized, and a phenol resin and a compound containing a 2-imidazolyl group, which itself forms a metal chelate and protects the metal surface, are used as the epoxy curing agent. and improve the performance of epoxy resins. Curing agents for epoxy resins include amines, polyamide resins, acids, and acid anhydrides. Some amines, such as diethylenetriamine, easily form metal chelates, but they react violently with epoxy resins, and during storage. As the curing progresses, gelation occurs, making it impossible to store the paint with good stability. Furthermore, when a polyamide resin, acid, or acid anhydride is used as an epoxy curing agent, the rust prevention effect is poor, probably due to the acid component in the curing agent.

In the present invention, the above-mentioned epoxy resin, phenol resin, and 2-imidazolyl group-containing compound are co-condensed to obtain a co-condensate with improved properties of the epoxy resin, and then a chelating reagent that forms a chelate compound with a metal is added. By further improving the properties of the co-condensate, it is possible to obtain a rust-preventing paint with high rust-preventing power without using any heavy metals or the like.

Among various reagents, aminophenol, 8-
It is necessary to use a chelating reagent having a hydroxyl group and an amino group in the same molecule, such as oxyquinoline. The amino group here may be any of a primary amino group, a secondary amino group, or a tertiary amino group. By using such a chelating reagent, the stability and antirust effect of the paint can be significantly improved. Other chelating reagents include those containing acid groups, such as salicylic acid and maleic acid, but these have low antirust effects. In addition, chelating reagents having two or more amino groups have the disadvantage of acting as curing agents for epoxy and impairing the stability of paints. Furthermore, when divalent and trivalent phenols are used as chelating reagents, the phenols are not converted into resins, so the coloring phenomenon is severe, and they are easily dissolved in solvents, especially when a top coat is applied. It has the disadvantage of causing a bleed phenomenon and discoloring the top coat.

In the present invention, the above chelating reagent is used as an epoxy resin.
It is preferable to mix 0.3 to 5 parts per 100 parts.
To give an example of manufacturing the coating composition of the present invention, first, the above-mentioned epoxy resin and phenol resin are added to an organic solvent and dissolved by heating and stirring, and then a 2-imidazolyl group-containing compound is added and heated and stirred. and react to obtain a co-condensate. When the chelating reagent used in the present invention is added and dissolved in the solution of this cocondensate, the desired coating composition is obtained. Various organic solvents can be used, but preferred are cellosolve solvents such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ketone solvents such as acetone and methyl ethyl ketone, and aromatic hydrocarbon solvents such as toluene and xylene. Other known paint additives may also be added.

The present invention will be explained below with reference to Examples.

Example 1 500 g of Epicote 1007 (epoxy equivalent 1750-2100, Ciel Chemical), phenol resin (Resistop)
PS-2780, light yellow lumps, Gunei Chemical) 50g, toluol 775g, ethyl cellosolve 775g 3/3
Pour into a neck flask, keep at 70-80℃ over a water bath, and stir gently to dissolve.

When Epicote 1007 and the phenolic resin are completely dissolved, 4 g of imidazole is added, heated to 95-98°C, and reacted at that temperature with stirring for about 3 hours. During that time, most of the imidazole and epoxy resin have reacted, and the compatibility between the phenolic resin and Epicote 1007 is poor, making it somewhat cloudy, but as the reaction progresses, the transparency increases, and after 2 to 3 hours of reaction, it becomes completely cloudy. Becomes transparent. Add and dissolve 5 g of para-aminophenol and cool to obtain 2100 g of a coating composition.

When 100 g of this composition was added with 25 g of toluene and 25 g of ethyl cellosolve and applied to a mild steel plate that had been degreased with a solvent, the dry coating film was 5 to 10 microns thick.
Further dry at room temperature for 4 days or 60℃ x 30 minutes or 120℃
As a result of a salt spray test (5% saline solution, 35°C) for 144 hours on a test piece that had been dried for 20 minutes at ℃, the peeling width of the cellophane tape from the part cut with a knife was within 1 mm. It was equivalent to a two-component wash primer that uses heavy metals as antirust pigments.

Apply the paint composition to a mild steel plate, aluminum plate, copper plate, stainless steel plate, galvanized steel plate, etc. as a metal base, dry at room temperature for 20 minutes, then apply melamine alkyd paint and bake dry for 20 minutes at 120℃. The test pieces were immersed in boiling water for 1 hour and then examined, but there were no abnormalities in appearance such as foaming, and no abnormalities in adhesion were observed.

Example 2 The main component of Chinese lacquer is urushiol, which is 2
It is a typical natural alkylated divalent phenol with a side chain attached to the monovalent phenol. When toluene is added to this Chinese lacquer and left to stand while stirring, it separates into a brown toluol phase at the top and an aqueous phase containing water at the bottom. The upper toluol phase contains toluol, the main component of raw lacquer, and when this solution is distilled under reduced pressure, a viscous liquid of urushiol is obtained. Urushiol
When you add 10g of urotropin to 200g and heat it, it becomes about 90%
The reaction begins with foaming at ℃. After stirring at 120 to 125°C for 30 minutes, foaming completely disappears, and a urushiol resin liquid that is viscous at high temperatures and solid at room temperature is obtained. This resin liquid is made by reacting urushiol and formalin in the presence of an ammonia catalyst, and due to the heating and ammonia, the lacquer flaking characteristic of raw lacquer is reduced, making subsequent operations easier.

Epicote 1009, (epoxy equivalent 2400-3000)
Put 500 g of the above urushiol resin solution, 800 g of toluol, and 800 g of ethyl cellosolve into a 3-necked flask from step 3, maintain the temperature at 70 to 80°C over a hot water bath, and stir to dissolve. When Epicote 1009 and urushiol resin liquid are completely dissolved, add 4 g of 2-methylimidazole.
is added, heated to 95-98°C, and stirred and reacted at that temperature for about 3 hours. 5g of 8-oxyquinoline after reaction
Add and dissolve to obtain 2150g of paint composition. When this coating composition was applied to a mild steel plate and a salt spray test was conducted, the same results as in Example 1 were obtained.

Comparative Example 1 A coating composition was obtained in the same manner as in Example 1 except that aminophenol was not added.

This coating composition was applied to a mild steel plate in the same manner as in Example 1 to a dry film thickness of 5 to 10 microns, and a test piece was subjected to a salt spray test for 144 hours. The peeling width was 6 mm.

Further, in the same manner as in Example 1, the above coating composition was applied,
After drying, apply melamine alkyd paint and heat at 120℃
The test piece was baked and dried for 20 minutes and immersed in boiling water for 1 hour. Using a knife, make cuts vertically and horizontally at 1 mm intervals to make 100 goblets. Peel off with cellophane tape to determine the number of remaining goblets. When I counted it, it was 0/100. On the other hand, the sample of Example 1 in which a chelating agent was added had a score of 100/100 and had no abnormalities at all.

Claims (1)

[Claims] 1 100 parts by weight of epoxy resin with an epoxy equivalent of 900 to 3000, 5 to 40 parts of monovalent or divalent phenolic resin
Hydrogen or carbon number 1 as a substituent in weight part and 2-position
A co-condensate consisting of 0.5 to 6 parts by weight of a 2-imidazolyl group-containing compound having ~4 alkyl groups, at least one selected from aminophenol and 8-oxyquinoline that binds with metal ions to form a chelate compound. 1. A rust-preventing coating composition comprising 0.3 to 5 parts by weight of a chelating reagent.