JPS61171778A - Corrosion-proofing coating composition - Google Patents

Abstract

PURPOSE:To provide the titled composition containing a solid resin component and a specific metal sulfide at a specific ratio, capable of forming a passive film of sulfide easily and industrially on a metal surface, and imparting effective anticorrosive property especially to the surface of a zinc-based metal. CONSTITUTION:The objective composition can be produced by compounding (A) 100pts.(wt.) of a solid resin component with (B) 1-500pts. of one or more sulfides of manganese, iron, vanadium, molybdenum, nickel or cobalt. The metal sulfide is preferably the one having a solubility of 1.0X10<-24>-1.0X10<-3>mol/l in water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anticorrosion coating composition, and more particularly, to an anticorrosion coating composition that prevents corrosion (for example, paint peeling, etc.) of painted metal.

Prior art and its problems As a corrosion prevention method for metals, for example, methods to block corrosive factors (painting, lining, etc.), adding soluble rust preventive substances to the paint film, and preventing water from penetrating into the paint film. Examples include a method of converting the metal surface under the coating film into a passive state mainly composed of oxides using soluble ions accompanying the coating, and a method of imparting an ion exchange function to the coating film to suppress the intrusion of anionic species.

Among these anticorrosion methods, the method of forming a passivation film mainly composed of oxides is the mainstream of today's anticorrosion technology. This technique is carried out by adding anticorrosive pigments with the function of passivating agents, such as oxides (e.g. chromic acid), oxidizing salts (e.g. chromates or molybdates), etc. into the coating. .

However, since oxides are inherently susceptible to attack by specifically adsorbed anions (e.g., halogen ions such as C!-ions) and are hydrophilic, consideration must be given to their interaction with water (solubility, stability, etc.). Therefore, it is difficult to say that it is the best rust prevention method. Therefore, passivation methods mainly using oxides are insufficient to impart the above-mentioned anticorrosion properties, and the development of even higher anticorrosion methods is desired.

The inventors of the present invention applied a hydrogen sulfide-containing gas or aqueous solution to a metal surface based on the assumption that a higher passivation effect could be expected if the passive film was formed with sulfide instead of oxide. In connection with this, we proposed a metal corrosion prevention treatment method that generates sulfide on the metal surface (Japanese Patent Application No. 59-253883).
No. 59-254448). Although these inventions have great anticorrosion effects, they are not necessarily industrially easy techniques because they deal with hydrogen sulfide.

OBJECTS OF THE INVENTION The present invention provides a means for industrially easily forming a sulfide passive film on a metal surface.

Means for Solving the Invention Namely, the present invention provides 1 to 500 parts by weight of at least one metal sulfide selected from the group consisting of manganese, iron, vanadium, molybdenum, nickel, and cobalt per 100 parts by weight of resin solid content. Provided is an anticorrosion coating composition containing:

The sulfide used in the present invention is manganese sulfide (MnSSM
nS2), metallic iron sulfide (F e S SF e S
s, Fe52), vanadium sulfide (vs4.VIS2)
, V2Sff), molybdenum sulfide (MoS, , M6S
3), nickel sulfide (NiS), cobalt sulfide (C
oS). Preferably, manganese sulfide (Mn
S), iron sulfide (F eS ), vanadium sulfide (V S
, ), molybdenum sulfide (MoS , ), and nickel sulfide (NiS).

The metal sulfide is 1.0XIO-“~1.0×10-
3 mol/i2, preferably 4 x 10-'' ~
It has a solubility product in water in the range of 3 x IQ-13.

The solubility product is 1. If it exceeds Ox l O-3 mol/IJ, it is not preferable because blistering due to water absorption of the film becomes significant. In addition, blistering can occur at least when the annular surface of the metal surface under the coating is exposed to strong alkalinity such as 6°2o or 70°C.
．． It's 90 years old. 11: There are problems such as difficulty in generating sulfides.

For example, strontium sulfide, barium sulfide, sodium sulfide, etc. fall into this category. On the other hand, the solubility product is 1, O
If it is less than XIO-" mol/Q, sulfide cannot be formed on the surface of the gold layer under the coating. Examples of this include zinc sulfide, lead sulfide, copper sulfide, etc. , corrosion resistance cannot be expected.

The particle size of the sulfide is the same as that used in pigments for paints, linings, adhesives, and the like. If the particle size is too large, the anticorrosion properties of the coating may be deteriorated. Metal sulfides may be prepared by any conventional method. for example,
It may also be produced by treating the oxide with hydrogen sulfide or the like.

In the present invention, the metal sulfide is preferably blended in an amount of 1 to 500 parts by weight, preferably 5 to 100 parts by weight, per 100 parts by weight of the resin solid content. If the amount exceeds 500 parts by weight, the performance of the coating film will deteriorate. Further, if the amount is less than 1 part by weight, the desired effect cannot be obtained.

The resin used in the present invention may be one generally used in paints or lining adhesives, and is generally a polymerized oil, a natural or synthetic resin alone or in combination. Examples include boiling oil and boiling oil. Examples of natural or synthetic resins include epoxy resins, epoxyurethane resins, cool epoxy resins, melamine resins, melamine alkyd resins, chlorine rubber, phenolic resins, epoxy/phenolic resins, polyester resins, polyurethane resins, silicone resins, and fluorine resins. etc. The coating composition of the present invention may be made into a dispersion using water or other solvents. Examples of other solvents include ketones, esters, and
Examples include glycols, alcohols, hydrocarbon solvents, and the like.

Conventional pigments or other additives may be added to the coating compositions of the invention. Examples of other additives include plasticizers, surfactants, desiccants, curing agents, thickeners, anti-sagging agents, and the like. The metal to be coated with the coating composition of the present invention is a usual coating metal, such as carbon steel or alloy steel including stainless steel, high-strength steel, non-ferrous metal such as copper, zinc, tin, aluminum, etc. their alloys,
Further examples include plated steel, thermal sprayed steel, metal whose surface has been subjected to caustic treatment or a film has been formed, and metal whose surface has been coated with paint containing zinc powder. Particularly desirable is a steel plate coated (sprayed, electroplated, or hot-dip plated) with zinc metal or these zinc-based metals.

Any conventional coating method may be used, such as flow coating, dipping coating, spray coating, brush coating, etc.
Examples include powder coating, electrodeposition coating, roll coating, etc.

Effect of the Invention When a metal is coated with the coating composition of the present invention, a sulfide film is formed on the metal surface under the coating due to the action of the metal sulfide in the coating composition, thereby stabilizing the metal surface. Unlike conventional oxide passive films, the metal surface on which this sulfide film is formed is hydrophobic and resistant to attack by specifically adsorbed anions such as C11,- ions, and has greater stability than oxides. The metal surface under the coating film is covered with a tough film that is hardly soluble. Furthermore, since sulfide is strongly hydrophobic, it also suppresses water penetration at the membrane/metal interface.

Effects of the Invention The coating composition of the present invention effectively prevents peeling, blistering, rust width, etc. of the coating film under a normal corrosive environment (an environment where Has is not present). In particular, it provides corrosion protection more effectively to zinc-based metal surfaces.

Example The present invention will be explained in more detail with reference to Examples.

Parts and percentages in the examples are by weight unless otherwise indicated.

Example I and Comparative Example I Using melamine alkyd resin as the resin vehicle,
A paint containing 30 parts by weight of the sulfide shown in Table 1 per 100 parts of resin was prepared, applied to a dry film thickness of 30 μl, and dried. Baking conditions (drying conditions) are 140℃
, for 30 minutes.

As for the metal to be coated, JIS G 3141 S
PjCC-SD (Dull Adjustment Board), a commercially available hot-dip galvanized steel sheet, and an electrogalvanized steel sheet were used. The corrosion test was a salt spray test, and after 500 hours, the peeling width (u
+) was investigated. The results are shown in Table-1.

For comparison, paints were prepared in which titanium oxide and strontium chromate were added instead of the sulfide of the present invention, and paints using a sulfide outside the scope of the present invention were prepared and tested in the same manner as in the above examples. The results are shown in Table-1.

Table - ■ Example ■ and Comparative Example ■ In this example, the effects of the present invention were measured by changing the composition of the sulfide of the present invention and the coating resin. The results are shown in Table-2.

The coating material was manufactured in the same manner as in Example I. In order to express the performance of the coating composition of the present invention, various paints were prepared containing strontium chromate, which was conventionally considered to have a good amount, in the same amount as the sulfide in Table 2, and the corrosion resistance of the coated plate was was the standard. That is, it was investigated whether the coating composition of the present invention had a higher corrosion resistance than a composition containing strontium chromate. The above standard value for corrosion resistance here is the ratio (i chromium/i sulfide) of the corrosion current value in the paint containing the sulfide of the present invention, when the corrosion current of the metal on the coating film is 100. It was displayed as a function. Corrosion current was measured according to the method described in Patent No. 960239. The corrosion conditions were the same as in Table 1, and the salt water spray test was 500 hours, and only in this example, the samples were placed in a 5% NaC (! solution) and the corrosion current was measured for 500 hours.

Table 2 Example ■ and Comparative Example ■ The sulfide-containing coating film of the present invention is effective in preventing corrosion on the inside and outside surfaces of ships, bridges, tanks, steel pipes, etc. However, in this example, rust had already formed. The effect on rusted steel plates was measured. The paint was prepared by replacing the rust-preventive pigment of a commonly available rust surface paint with manganese sulfide, which is one of the sulfides of the present invention. This paint was left unpainted under atmospheric pressure for one year to prevent rust from forming on steel plates (JIS G 314L).
5PCC) using the usual method to create a painted board.

The rust occurrence status after 500 hours of salt spray test was determined by ASTM, D.
610-68. For comparison, a similar test was conducted using a commercially available rust paint. The results are shown in Table-3.

Table 3 A similar test to the above was conducted on a galvanized steel plate with rust, and similar effects were found.

Example (2) and Comparative Example (2) In this example, the effect of the present invention on corrosion protection of reinforcing bars and steel materials in concrete was measured.

The paint uses an epoxy resin system, and contains 10 parts of molybdenum sulfide.
Each paint containing 10 parts of strontium chromate was prepared and spray-painted onto ordinary reinforcing bars to a film thickness of about IOμ.

Then, the painted reinforcing bars were covered with concrete so that the concrete fog thickness was 711M, and after one month, they were fixed in the tidal zone of the sea, and after one year of fixation, the concrete membrane was destroyed and the corrosion status of the painted reinforcing bars was visually observed. I observed it. Table 4 shows the results.
Shown below.

Table-4 (○: No rusting or peeling of paint film observed.

△: There is some rust and some peeling of the paint film.

Claims (1)

[Claims] 1. At least 1 to 5 parts of a metal sulfide selected from the group consisting of manganese, iron, vanadium, molybdenum, nickel and cobalt per 100 parts by weight of resin solid content.
An anticorrosion coating composition containing 00 parts by weight. 2. The composition according to item 1, wherein the resin is a natural or synthetic resin, or a polymerized oil alone or in combination. 3. Metal sulfide is 1.0x10^-^2^4~1.0x
3. A composition according to claim 1 or 2, having a solubility product in water in the range 10-3 mol/l.