JPH0873777A - Rust preventive coating composition - Google Patents

Abstract

PURPOSE: To obtain an rust preventive coating composition improved in workability, weldability and rust prevention and reduced in the formation of zinc fume even when it is sprayed with an airless spray coater for a long time by using a silicic inorganic binder, a zinc powder and a lubricant as the principal components. CONSTITUTION: This composition is obtained by mixing 40-60 pts.wt. inorganic silicic compound being a silicic ester hydrolytic condensate prepared by the hydrolysis and condensation of at least either a tetraalkyl silicate or an alkyl trialkoxysilicate or a silicic alkali, silica sol, polysiloxane or like compound with 30-50 pts.wt. zinc powder of a mean particle diameter of 3-15μm, 30-50 pts. wt. zinc powder of a mean particle diameter of 3-15μm, 0.5-20 pts.wt., per 100 pts.wt. zinc powder, at least one lubricant selected from among graphite, molybdenum disulfide, etc., 10-60 pts.wt., 100 pts.wt. zinc powder, at least one conductive powder selected from among a magnetic iron sand powder, a reduced iron powder, etc., at least one heat-resistant powder used in an amount about a half of the amount of the conductive powder and selected from among a rutile sand powder, a magnesite powder, etc., and optionally additives such as a pigment and a solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rust preventive coating composition, and more particularly, it has good workability when automatically applied to steel materials used for ships, bridges, marine steel structures, etc. Processing into the above structure, welding when assembling, fusing, and the coating film does not peel off even in the process involving high heat such as strain relief, and the weldability and heat and rust preventive composition capable of sufficiently exhibiting anticorrosive properties It is about things.

[0002]

2. Description of the Related Art Generally, steel materials used for building large-scale steel structures such as ships, bridges, tanks and plants are treated with a primary rust preventive paint after blasting to prevent rusting of the steel materials during processing and assembly work. Is being painted.

As such a primary rust preventive paint, a wash primer made of butyral resin-phosphoric acid-chromate, an organic zinc rich paint made of epoxy resin-zinc powder, and an inorganic zinc zinc silicate-zinc powder have hitherto been used. Rich paints, new inorganic zinc paints composed of organic resin-ethyl silicate-zinc dust, etc. are known.

And, in such a primary rust preventive paint,
Functions such as (1) excellent rust resistance, (2) excellent welding workability, and (3) adhesion to any topcoat paint are required. ,
Among the above paints, inorganic zinc rich paint and new inorganic zinc paint, when applied to steel materials, sacrificial anticorrosion action of zinc due to electrochemical action between zinc in the coating film and steel surface, and zinc corrosion The product has a rust preventive effect by blocking oxygen and moisture, and is often used as a primary rust preventive paint for steel materials for large steel structures.

[0005]

However, in recent years, in the construction of the above-mentioned large-scale steel structures, the welding work is automated and speeded up from the viewpoint of streamlining work processes such as welding, fusing, strain relief, and labor saving. However, carbon dioxide arc automatic welding is becoming mainstream, but with the improvement of welding speed, the conventional inorganic zinc rich paint has a large content of zinc dust,
Although it has high rust resistance, when the coating film is heated to high heat, toxic gas such as zinc fume is generated due to melting and vaporization of zinc, and this gas causes welding defects such as blowholes and pits. There's a problem. If the amount of zinc dust is reduced in order to avoid this, the rust resistance is reduced, the coating film is hard,
It becomes brittle and easily cracks, making it difficult to form a coating film. On the other hand, the content of zinc dust is lower than that of the inorganic zinc-rich paint, but with the new inorganic zinc paint that also uses an organic resin, the adverse effects of the organic resin being hard and brittle can be mitigated. It is pointed out that the heat resistance is poor due to the resin, and welding defects due to hydrogen gas generated during welding work.

[0006] Furthermore, since it is preferable to use a paint that is unlikely to cause welding defects, the rust preventive paint excluding the organic resin should be applied when it is automatically applied to the steel surface by an airless spray paint machine. There is a problem that the zinc powder in the paint adheres to the inner wall of the feed piston in the coating machine as the time elapses and the coating efficiency decreases.

[0007] From the above, while maintaining the good antirust property of the conventional inorganic zinc-rich paint, the paintability,
A rust preventive paint having excellent heat resistance and weldability has been demanded, and for example, a rust preventive paint having heat resistance even if the amount of zinc dust is reduced by specifying the composition of a silicon-based binder (Japanese Patent Laid-Open Publication No. Sho 6-96).
No. 0-51756 and JP-A No. 60-235871, the use of zinc alloy powder as a rust preventive pigment maintains the rust preventive property at high temperature heating (Japanese Patent Publication No. 63-
No. 52068), which uses zinc dust surface-treated with conductive particles to maintain rust resistance at high temperature heating (Japanese Patent Publication No. 62-53552), and when ferrosilicon is used together with zinc dust at high temperature heating. Which maintains the rust preventive property of JP-A-5-117553, which improves the high temperature weldability by using zinc powder and a molybdenum-containing pigment (JP-A-5-339521), zinc powder and molybdenum Weldability is improved by using a compound in combination to prevent the oxidation of zinc during heating (Japanese Patent Laid-Open No. 6-100803) and by incorporating at least one of a phosphate pigment and feldspar in the coating composition. Thing (JP-A-6
-200188).

However, although these proposed coating compositions have their respective advantages, they all suffer from the problem that the efficiency of the coating work is lowered due to the above-mentioned reasons during long-time spray coating by an automatic spray coating machine. However, the problem of zinc fume generation and rust prevention at high temperature heating has not been improved yet.

In view of the above, the present invention is excellent in workability even in long-time coating with an airless spray coating machine,
Moreover, it is an object of the present invention to provide a rust preventive coating composition having excellent weldability and rust preventive property by suppressing the generation of zinc fume at the time of high temperature heating welding of a coated steel material.

[0010]

That is, the first invention of the present invention is characterized by a rust preventive coating composition containing a silicon-based inorganic binder, zinc dust and a lubricant as main components, and a second invention. Is a rust preventive coating composition comprising a silicon-based inorganic binder, zinc dust, and a lubricant, and conductive powder as a main component.
A third invention is a silicon-based inorganic binder, zinc powder, a lubricant,
Further, the present invention is characterized by a rust preventive coating composition prepared by mixing conductive powder and heat resistant powder as main components.

[0011]

As described above, the present invention provides a silicon-based inorganic binder,
By using a paint containing zinc powder and a lubricant as the main components, a paint containing electrically conductive powder as the main component, and a paint containing heat-resistant powder, the obtained rust-preventive paint was applied to steel materials. In particular, it improves the coating workability when automatically coating with airless spray, and reduces the amount of zinc dust in the cured coating without lowering the rust preventive property due to zinc dust, and improves the zinc fume content during welding work. The amount generated can be reduced.

As the silicon-based inorganic compound used as the binder solution in the present invention, tetramethoxysilicate, tetraethoxysilicate, tetrapropoxysilicate,
Tetraisopropoxysilicate, tetraalkoxysilicate such as tetrabutoxysilicate or methyltrimethoxysilicate, methyltriethoxysilicate, methyltripropoxysilicate, ethyltrimethoxysilicate, ethyltriethoxysilicate, butyltrimethoxysilicate, amyltriethoxysilicate, etc. The hydrolyzed condensate of a silicic acid ester obtained by hydrolyzing and condensing alkyltrialkoxysilicates alone or in a mixture of two or more kinds by a conventional method, or a compound such as an alkali silicate type, a silica sol type, a polysiloxane type, and the like are used. Is suitably 40 to 60 parts by weight.

As the zinc powder, commercially available products can be used, but those having an average particle size of 3 to 15 μm are preferable. The usage amount is 3
0 to 50 parts by weight is suitable. This is because if the amount is 30 parts by weight or less, good rust prevention cannot be obtained, and if it exceeds 50 parts by weight,
This is because the workability at the time of painting is reduced and a large amount of zinc fume is generated during welding, which causes welding defects.

As the lubricant, at least one selected from graphite, molybdenum disulfide, carbon fluoride, boron nitride, silicon nitride and Teflon powder is used, and the amount thereof is 100 parts by weight of zinc powder. Against 0.5
In parts by weight or less, when spray-painting the obtained rust-preventive coating composition on steel, the effect of improving the deterioration of coating workability due to zinc dust adhering to the inner wall of the coating pipe and nozzle of the coating machine , And if more than 20 parts by weight is used,
Although an effect is recognized in improving the coating workability, it may lead to a decrease in rust preventive property, so 0.5 to 20 parts by weight is preferable, and optimally 1 to 10 parts by weight.

In the present invention, a coating composition obtained by adding conductive powder to the above-mentioned binder, zinc dust and lubricant is added to the zinc composition during welding without lowering the rust preventive property. It is possible to reduce the amount of fume generated, and by further incorporating heat resistant powder,
It is possible to obtain a coating composition having excellent rust prevention properties and welding workability even at higher temperatures.

As the conductive powder, at least one selected from magnetic sand iron powder, reduced iron powder, phosphorous iron, ferro-molybdenum powder, ferro-manganese powder, ferro-nickel powder, graphite, etc. may be used, and the amount thereof is used. , Zinc dust 100
If the amount is 10 parts by weight or less relative to the parts by weight, the amount of zinc fume generated cannot be expected to decrease, and if it is used in an amount of 60 parts by weight or more, the rust-preventive property is deteriorated. 30 to 50 parts by weight.

The heat-resistant powder plays a role of doubling the effect of the above-mentioned conductive powder when used in combination with the conductive powder. Examples of such heat-resistant powder include rutile sand powder, magnesite powder, At least one selected from silica phosphate powder, wollastonite powder, and zircon sand powder may be used, and the amount used is about 1/2 of the amount of the conductive powder.

In obtaining the rust-preventive coating composition of the present invention, in addition to the above-mentioned essential components, a pigment, a solvent, and other additives may be added, if necessary, as in the case of a normal rust-preventive coating composition. Similarly, as the pigment, extender pigments such as silica powder, talc, clay, mica powder, barium sulfate, calcium carbonate, and alumina, pigments, titanium dioxide, carbon black, organic blue, organic yellow, organic green, etc. Pigments,
A rust preventive pigment such as a phosphate type, a borate type or a chromate type is used.

Suitable solvents include alcohol solvents such as isopropyl alcohol and isobutyl alcohol, and aromatic solvents such as toluene and xylene. As other additives, anti-settling agents such as organic bentonite, polyethylene oxide, and Aerosil, anti-sagging agents, and stabilizers may be used according to the purpose.

The rust preventive coating composition of the present invention can be prepared by separately preparing a binder solution as a main component and a component (paste component) below zinc dust, and mixing both components when coating a steel material. Often, airless spraying is most efficient, but airspraying is also possible.

[0021]

EXAMPLES The present invention will be described in detail below with reference to examples. All parts are parts by weight.

(Preparation of Binder Solution) Tetraethoxysilicate (Ethylsilicate 40: manufactured by Nippon Colcoat)
A 1-liter reaction vessel charged with 304 g and 304 g of isopropyl alcohol was heated and kept at 60 ± 3 ° C., and a mixed solution of 0.6 g of 35% hydrochloric acid, 36.2 g of deionized water and 75.2 g of isopropyl alcohol was stirred therein. While adding gradually over 1 hour, continue stirring at the same temperature for 1 hour, and finally add isopropyl alcohol 8
A binder solution consisting of an isopropyl alcohol solution of the ethyl silicate hydrolyzed condensate was prepared by adding 6.4 g and then allowing to cool.

(Preparation of Paste) Each raw material forming the pastes shown in Comparative Examples and Examples 1 to 19 in Table 1 below was placed in a 1-liter container and sufficiently stirred and dispersed to prepare a paste.

The following materials were used as the raw materials constituting the paste. Zinc dust (Zinc dust F-2 manufactured by Honjo Chemical Co., Ltd.
000) Silica powder (Silica powder M manufactured by Maruo Calcium Co., Ltd.
C-O) Graphite (Nishimura Graphite, Graphite PS
-99) Phosphorus iron (Hooker Chemical Co., Ferrofos 2131) Magnetic sand iron powder (Kinsei Matec Co., sand iron) Zircon sand powder (Kinsei Matec Co., zircon sand powder A-PAX) Wollastonite powder (Kinsei Matech Co., Wycor ) Organic Bentonite (NL Chemical Co., Benton SD
-2) Oxidized polyethylene (Kusumoto Kasei Co., 20% xylene solution)

(Preparation of Anticorrosion Paint) Each of the anticorrosion paints used in Comparative Examples and Examples 1 to 19 was prepared by thoroughly mixing the binder solution and the paste in the amounts shown in Table 1 below.

[0026]

[Table 1]

(Preparation of Test Pieces) Using each of the paints thus obtained, 70 × 150 × 3.2 m for rust prevention test
100 x 500 x 12 for measuring the amount of zinc fume generated during welding and fusing on 2 pieces of m sandblasted steel plate
A mm sandblasted steel sheet was coated with an airless spray so that the dry coating film thickness was 15 μm, and dried at room temperature for 7 days to prepare a test piece. Then, the following tests were conducted using these test pieces.

(Rust-proof test) Of the two test pieces for rust-proof test obtained above, one piece was left as it was, and the other piece was heat-treated with a gas burner at 800 ° C. for 1 minute. After performing outdoor exposure for 6 months, the rust-preventive property was evaluated according to 4 grades of A: good, B: somewhat good, C: slightly bad, and D: poor. The results are shown in Table 2.

(Measurement of Zinc Fume Generation during Welding / Fusing) Using the test piece for measuring zinc fume generation during welding and fusing obtained above, 1.0 × 1.0 × 1.0 m Welding work is carried out in a box of a size, the zinc fume generated at that time is adsorbed on the filter paper attached to the suction pump inside the box, this filter paper is melted with hydrochloric acid, and zinc fume is generated by the atomic absorption method. The amount (g / m ³ ) was measured. The results are shown in Table 2. The workability of the airless spray coating machine shown in Table 2 was evaluated as follows: good workability was evaluated by circulating the paints adjusted as described above in the airless spray coater for a long time. It was judged in three stages of good and bad: bad.

[0030]

[Table 2]

Considering the results shown in Table 2, first, the workability of the airless spray coating machine according to the present embodiment showed good results in comparison with the comparative examples. Regarding the rust prevention property, as in Examples 1 to 4 and 6 and 7, good results were shown only by adding the lubricant, but when the amount was more than the specified amount, Thus, it was found that the rust preventive property deteriorates.

When the lubricant, the conductive powder and the heat resistant powder are added, the rust preventive property is good even if the amount of zinc powder varies as in Examples 8 to 12 and 14 to 16. It was also confirmed that the amount of zinc fume generated decreased. However, when the amount of zinc powder was reduced and a large amount of conductive powder was used, the rust preventive property was naturally lowered as in Example 13. Further, it was found that when the amount of the binder was increased or decreased from the specified amount of the present invention, the rust preventive property was affected as seen in Examples 17 and 19.

[0033]

As described above, according to the present invention, a lubricant, a lubricant, and
By adding a certain amount of conductive powder and heat resistant powder, it is possible to coat for a long time without any trouble even with an air spray or airless spray coating machine, so improve the efficiency of coating work. In addition, the rust preventive property is good and the amount of zinc fume generated during welding work can be suppressed regardless of the increase or decrease in the amount of zinc dust.

Claims (9)

[Claims] 1. A rust preventive coating composition comprising a silicon-based inorganic binder, zinc dust and a lubricant as main components. 2. A silicon-based inorganic binder, zinc dust, lubricant,
Further, a rust-preventive coating composition containing a conductive powder as a main component. 3. A silicon-based inorganic binder, zinc dust, lubricant,
Furthermore, a rust-preventive coating composition comprising a conductive powder and a heat resistant powder as main components. 4. The anticorrosive coating composition according to claim 1, 2 or 3, wherein the lubricant is at least one selected from graphite, molybdenum disulfide, carbon fluoride, boron nitride, silicon nitride and Teflon powder. Stuff. 5. The anticorrosive coating composition according to claim 1, 2 or 3, wherein the lubricant is used in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of zinc dust. 6. The anticorrosive coating composition according to claim 2 or 3, wherein the conductive powder is at least one selected from magnetic sand iron powder, reduced iron powder, phosphorous iron powder, ferroalloy powder, and graphite. 7. The anticorrosive coating composition according to claim 2, wherein the conductive powder is used in an amount of 10 to 60 parts by weight based on 100 parts by weight of zinc dust. 8. The anticorrosive coating composition according to claim 3, wherein the heat resistant powder is at least one selected from rutile sand powder, magnesite powder, silica phosphate powder, wollastonite powder and zircon sand powder. 9. The anticorrosive coating composition according to claim 3, wherein the heat resistant powder is used in an amount of 40 to 60 parts by weight based on 100 parts by weight of the conductive powder.