JPH0676562B2 - Rust prevention paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an improvement in a rust preventive coating, and by particularly enhancing the penetrability of the coating into an iron substrate or a rust layer, an excellent rust preventive effect can be obtained. It is related to the paint that is made possible.

(Prior Art) It is a well-known fact that, when coating an iron substrate or the like, the quality of rust removal greatly affects the rust-preventive life of the coating film after coating. For this reason, it is necessary to completely remove rust from the coated surface, but it is difficult to completely remove rust because it causes a significant increase in coating cost. Even if complete rust removal is performed, an oxide film will be formed on the iron surface activated by the rust removal from the rust removal to the painting, and complete rust removal is physically Is also impossible.

Therefore, in the paint industry, paints that can be painted on even if some rust remains on the iron ground have been developed, and released under the names such as rust preventive paint, undercoat paint, and rust paint. ing. That is, by applying (a) red rust to black rust, (b) rust to fatty acid iron,
(D) Stabilize the rust layer by changing rust to iron phosphate, etc., or (e) changing rust to iron chelate,
This is used as a constituent material of a coating film, and is commercially available as an oil-based / resin-based rust preventive paint, a chelate-based rust preventive paint, and a phosphoric acid-based rust preventive paint.

However, each of the above-mentioned various conventional rust-preventing paints has a relatively weak penetrating power into the iron ground or the rust layer, and cannot convert rust into a stable substance. As a result, when the rust layer remaining on the coated surface is thick, the remaining rust that is not stabilized acts as an oxidizer to accelerate the oxidation of iron, or the adhesion of the coating film to the iron substrate is This hinders deterioration of the rust preventive property of the coating film.

In other words, this conventional rust preventive paint mainly prevents rusting by blocking the intrusion of water and air from the outside, and when the rust layer remains on the iron ground surface, However, there is a drawback that it cannot exert a sufficient rust preventive effect. As a result, in order to obtain sufficient rust prevention effect, (a) strict rust removal and so-called first-class keren rust removal are required, or (b) brush coating to promote the penetration of paint. In some cases, spray coating is not allowed, which is a major obstacle in reducing coating costs and improving work efficiency.

(Problems to be Solved by the Invention) The present invention has the above-mentioned problems in the conventional rust preventive coating, that is, the penetration of the coating into the rust layer remaining on the coated surface or the iron substrate is weak, It is not possible to completely stabilize the rust that occurs, which shortens the rust-preventive life of the coating film, and requires more complete rust removal to reduce the coating cost. By increasing the penetrating power of the paint to the rust layer and the iron ground, the residual rust layer is completely stabilized and the adhesion of the coating film on the iron ground is strengthened, extending the rust prevention life and rust prevention. It is intended to provide a rust preventive paint which can simplify the work.

(Means for Solving the Problems) When the present inventor had previously visited Europe for a paint visit, in France, by mixing meta-cresol with the paint, it was attempted to enhance the penetration power of the paint into the rust layer. I got to know the paint.

After 20 years of returning to Japan, repeated coating experiments and adding 15-20% of meta-cresol to rust preventive paint
It has been found that even on a ferrous ground material in the seed-type keren state, it is possible to form a coating film having the same rust-preventive effect as that of the coating material formed on the iron substrate in the first-class keren state.

However, since the meta-cresol is a poisonous deleterious substance, there remains a problem in terms of safety and the like, and it has not been possible to put the paint containing the meta-cresol into practical use in Japan. Therefore, the inventor of the present invention seeks for a substance having properties that are alternatives to the meta-cresol and that is safe,
Numerous paint tests were conducted on various paints.

The present invention has been created through the above-mentioned diameters, and is 6-10% by weight of red lead, 6-10% by weight of valve stem, 30-50% by weight of calcium carbonate, 30-50% by weight of alkyd resin and toluol. % And a flow stop agent 2 to 6% by weight (A),
The basic composition of the invention is to mix 10 to 30% by weight of the coating material (A) with N-methyl-2-pyrrolidone (B).

(Operation) By applying the paint to the surface of the iron substrate, the pigment in the paint acts as a catalyst to convert red rust into black rust, or the so-called chelate reaction stabilizes the rust layer.

By the N-methyl-2-pyrrolidone in the paint, the penetrating power of the paint into the rust layer and the penetrating / fixing power to the iron surface are greatly increased, and even if the rust layer is thick, all of the rust can be quickly removed. It is stabilized and the adhesion of the coating film is significantly improved.

The stabilized rust layer remains in the coating film as a constituent of the coating film, and when the coating film is cured, the rust layer is firmly fixed to the iron ground surface integrally with the coating film.

(Example) Hereinafter, one example of the rust preventive coating material according to the present invention will be described.

The rust preventive coating material according to the present invention is formed by mixing the coating material A and the solvent B. The paint A is 8% by weight
Of red lead, 8% by weight of rouge, 40% by weight of calcium carbonate as a pigment, to which 40% by weight of a mixture of medium oil alkyd resin and toluol and 4% by weight of anti-flow agent were added. In this embodiment, the mixing ratio of the medium oil alkyd resin and the toluol is selected to be 1: 1 (weight ratio).

Further, as the solvent B, N-methyl-2-pyrrolidone, which is a nitrogen-containing five-membered ring compound having a constitution as shown in the drawing, is used, and 15% by weight of the solvent B with respect to the paint A is used. The rust preventive coating material of the present invention is formed by mixing

The N-methyl-2-pyrrolidone (NMP manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) is a low-boiling solvent having a high boiling point, has a large polarity and is completely mixed with most organic solvents, and has a dissolving power for organic and inorganic substances. It is a material with a large surface tension and a relatively small surface tension (41 dynes Cm at 25 ° C).

In this example, when the coating material A was formed, the ratio of each component was 8% by weight of red lead, 8% of rouge, 40% of calcium carbonate,
Mixture of alkyd resin and triol 40%, flow stop 40
%, Of course, the respective component ratios are not limited to the above-mentioned values, and the desirable mixing ratio is 6-10% of red lead, 6-10% of rouge, and calcium carbonate of 30- 50
%, A mixture of alkyd resin and triol 30 to 50%, and a flow stop agent 2 to 6%.

Further, in this embodiment, 15% by weight of the paint A is used.
The solvent B is mixed, but the mixing ratio of the solvent B is preferably 10 to 30% by weight of the paint A.

Further, in this embodiment, the mixing ratio of the alkyd resin and the toluol is selected to be 1: 1 (weight ratio), but it is desirable to select the mixing ratio of both (resin / solvent) to 2 to 0.7.

In addition, although a medium oil alkyd resin is used as the alkyd resin in this example, it goes without saying that a long oil alkyd resin or a super long oil alkyd resin may be used.

Next, various performances of the coating film formed by the rust preventive coating material according to the present invention will be described.

(A) Anticorrosion performance of coating film: A rust preventive coating composition according to the embodiment of the present invention (a coating composition containing 15% by weight of solvent B (NMP)).
A weather resistance comparison test was performed on the coating film by using, instead of the solvent B, a rust-preventive paint (a mixture of the paint A and 15% by weight of the paint thinner) using a normal paint thinner. .

That is, the surface of four rust iron plates (30 Cm x 30 Cm) is derusted,
Two sheets were rust-proofed to the first-class keren state and the other two were rust-proofed to the third-class keren state.

Next, one set of the first type keren and the third type of keren removed rust plate is used as a set, and the rust preventive paint of the present invention and the rust preventive paint for the comparative test are sprayed onto the iron substrate of each set of iron plates. Used to form a 100 micron thick coating.

Two sets of iron plates (four sheets in total) on which the coating film was formed were exposed for 4 years, and then the rusting condition was observed. As a result, in the case of the rust-preventive coating material of the present invention, neither rusting, rising of the outer surface, nor peeling of the coating film occurred at all on both iron plates in the first-class keren and the third-class keren state. On the other hand, in the case of the anticorrosive paint for comparative tests, a plurality of spot-shaped rusts were observed on the iron plate in the third-class keren state, and the coating film was partially lifted.

As is clear from the comparative test, the coating film of the rust preventive application material according to the present invention exhibits a sufficient rust-preventing effect even when the rust layer is slightly left on the iron ground, and the rust removal level B) Toughness test of coating film Rust iron plate in 3rd class keren state (thickness 3mm, width 5mm, length 15mm)
Two sheets were prepared, and a coating film having a thickness of about 100 μm was formed on each iron plate by brushing, using the rust preventive paint of the present invention and the rust preventive paint for comparative test. 2 of the paint
After being naturally dried at 0 ° C to 30 ° C for one week, it was curved in a U-shape along a mold rod having a diameter of 6 Cm.

As a result, the coating film using the rust preventive paint for comparative tests is
Although small cracks were generated on the entire surface of the curved surface, no cracks were generated on the coating film of the rust-preventive coating material of the present invention, and high toughness of the coating film was confirmed.

(Effect of the Invention) In the rust preventive coating material according to the present invention,
Since 10 to 30% by weight of N-methyl-2-pyrrolidone is mixed as the solvent B, the properties of the solvent B such as large polarity, high dissolving power and low surface tension are organically different from those of the paint A component. Therefore, the penetrating power of the paint into the rust layer and the iron ground is significantly improved, and the adhesion of the paint to the iron ground is significantly solid.

As a result, even if some rust layer remains on the iron surface, all of those rust layers are stabilized by the coating components, and the stabilized rust layer forms a part of the composition of the coating film. As a result, it will be firmly fixed to the iron surface, and it will exhibit extremely strong rustproofing effect for a long time. That is, the conventional rust preventive coating cannot fully stabilize the inner part of the rust layer due to its weak penetrating power, and even if the rust layer is stabilized by a chelate reaction, etc. Since the adhesive strength to the iron ground surface is relatively low, local peeling of the coating film easily occurs near the stabilized rust layer, and there was a problem of rusting from the peeled portion. In the case of paint, the above-mentioned rusting is almost completely prevented.

Moreover, the coating film of the rust preventive coating composition of the present invention has excellent toughness, and can exhibit a high rust preventive effect over a long period of time.

As described above, in the rust preventive coating material according to the present invention,
Even if some rust layer remains on the iron substrate, it is possible to form a coating film with strong rust prevention effect and weather resistance on the iron substrate, so it is possible to simplify the difficult rust removal work in so-called painting. As a result, the coating cost can be drastically reduced and the coating work efficiency can be improved, and it has excellent practical utility.

[Brief description of drawings]

The drawing shows the chemical structure of solvent B (N-methyl-2-pyrrolidone) used in the present invention.

Claims (1)

[Claims] Claims: 1-10% by weight of red lead, 6-10% by weight of rouge, 30-50% by weight of calcium carbonate Alkyd resin and toluol 30
A rust preventive coating composition comprising a coating composition (A) containing 50 to 50% by weight and a flow stopper of 2 to 6% by weight and 10 to 30% by weight of the coating composition (A) with N-methyl-2-pyrrolidone (B).