JPS60235872A - Rust-resisting paint composition - Google Patents

Abstract

PURPOSE:To provide the titled paint compsn. which can impart excellent primary rustproofness, exhibits excellent rustproofness even at those parts which are heated at a high temp. and is suitable for use in coating large steel structures, containing a specified zinc alloy powder. CONSTITUTION:At least one member selected from among Fe (0.1-60wt%), Ca (1-40wt%), Na (0.5-10wt%) and K (0.5-10wt%) is added to metallic zinc, and the mixture is molten to prepare an alloy which has a m.p. higher than that of zinc and exhibits a lower potential than that of iron. The alloy is crushed and classified to obtain a zinc alloy powder having a particle size of 1-2mu. A binder (e.g. a precondensate of a hydrolyzate of a silicate), a solvent (e.g. isopropyl alcohol or toluene), said zinc alloy powder (in such a quantity as to give 20- 95wt% based on that of dry film) and other additives are blended together to produce a rust-resisting paint compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a rust-preventing paint composition with excellent heat resistance. More specifically, it relates to a primary rust-preventing paint composition that is effective as a primary rust-preventing paint for large steel structures and that is capable of maintaining rust prevention on the back surface during heating for welding, strain relief, etc. .

[Prior art] Many anti-rust paints are known that contain various anti-rust pigments, but among them, zinc-rich paint containing zinc powder has excellent anti-rust properties and is used for large steel structures such as ships and bridges. It is widely used as a primary anti-rust coating. Zinc-rich paint is generally obtained by mixing a large amount of zinc powder with an organic or undefeated binder, and is used to prevent sacrificial corrosion of zinc through electrochemical interaction between the zinc in the paint film and the steel surface. It also has a rust-preventing effect due to the corrosion products of zinc that block oxygen and moisture. However, this sink lynch paint also has the following drawbacks. That is, non-phantom Lunotibaisite certainly has higher rust-preventive power than anti-rust paints made of other ingredients, and can provide the desired rust-preventive properties for general parts of steel structures. However, for parts heated to high temperatures, such as the back side of welds and the back side of strain relief, the oxidation of zinc in the coating film becomes significant due to the heat, reducing the sacrificial anticorrosion effect, and the rust prevention property also decreases. The purpose of preventing rust is not achieved.

Large steel structures have many welding points and strain relief points, and as a result, even though they are coated with anti-rust paint, it takes a lot of effort to remove the rust before applying the top coat. This is the current situation. Therefore, there is a desire for a paint that exhibits good lactic properties even in such locations.

[Purpose of the Invention] As a result of intensive research, the present inventors have found a zinc alloy powder containing additive elements such as Fe, Ca, Na, etc., which has a higher melting point than zinc alone and is less base than iron. It was discovered that those having a potential can significantly suppress high-temperature oxidation and maintain rust prevention even in high-temperature heated parts corresponding to the back surface of welding and the back surface of strain relief, and have completed the present invention.

Therefore, the object of the present invention is to exhibit rust prevention properties equivalent to conventionally known primary rust prevention paints in general areas that are not heated;
The present invention also provides a coating composition that can exhibit superior rust prevention properties in high-temperature heating parts compared to conventionally known primary rust prevention coatings.

[Structure and effect 1 of the invention That is, the gist of the present invention resides in a rust-preventing paint composition characterized by containing a zinc alloy powder having a melting point higher than that of zinc and a potential less noble than iron. .

The zinc alloy powder of the present invention may be produced in the same manner as ordinary alloy powder. For example, zinc base metal and additive elements or their compounds (e.g., Fe, CaCl2, NaCl, KC
A molten metal having a predetermined alloy composition is produced from I) by a melting method or an electrolytic method, and this is pulverized by a spraying method or a mechanical pulverization method (e.g., ball mill, stamp mill, etc.), and the particle size is adjusted by sieving. The particle size may be approximately 1 to 20 μm, preferably 2 to 10 μm, which is the same as that of ordinary pigments.

The content of additional elements in the zinc alloy powder thus obtained may be appropriately selected as long as the powder has a melting point higher than that of zinc and a potential more base than iron. Specifically, In weight% (1,1≦Fe≦60
．． 1≦Ca≦40, 0゜5≦Na≦10, 0.5≦≦
10 is fine.

The additive elements are not limited to one type, but may be contained in a combination of two or more types. If the content of the added element is less than the above range, the high-temperature oxidation of the zinc alloy powder will be insufficiently suppressed, and therefore it will be difficult to maintain rust prevention in the high-temperature heating section. If the amount is too large, the zinc alloy powder will be leached out and consumed too much, making it impossible to obtain long-term anti-rust properties.

The binder in the composition of the present invention may be any binder used in anticorrosive paints, such as hydrolytic initial condensation of silicate esters (e.g., ethyl silicate, methyltriethoxysilicate). silicates (eg, sodium silicate, lithium silicate, ammonium silicate), epoxy resins, silicone resins, and the like.

When organic resin binders are exposed to high temperatures for welding or strain relief, they decompose and are no longer able to maintain the coating film. Preferably, a salt-based binder is used.

In the composition of the present invention, the zinc alloy powder may be blended so that the content in the dry casing film is 20 to 95% by weight, preferably 40% by weight or more. If the amount is too small, it will not be possible to obtain the same good rust prevention properties as normal non-crystalline paint, and if it is in excess, the binder will inevitably be insufficient and a normal coating film will not be obtained. do not have. In the present invention, one type or a combination of two or more of the above zinc alloy powders may be used, and zinc powder may also be used in combination. In the latter case, the zinc alloy powder is 5% by weight in the total amount of both.
Similar effects can be expected if the total amount is within the above-mentioned regulatory range for the coating composition.

In the composition of the present invention, in addition to the above-mentioned zinc alloy powder, zinc dust, and binder, various pigments, solvents, additives, etc. may be blended as necessary in the same manner as in ordinary antirust paints. . Pigment components may be ordinary extender pigments, anti-rust pigments, and coloring pigments, specifically talc, mica, barium sulfate, clay, calcium carbonate, zinc white, titanium white, Bengara, zinc phosphate, and aluminum phosphate. , barium metaborate, zinc molybdate, aluminum molybdate, zinc phosphomolybdate, iron phosphide, and the like. As a solvent component, usual isopropyl alcohol, 11-butyl alcohol, isobutyl alcohol, butyl cellosolve, ethyl cellosolve, doluol, quijirol, MEKJII
Examples include BK, etc., and may be blended in an appropriate amount so as to optimize coating workability and coating film drying properties. Additive components include anti-sagging agents, wetting agents, reaction accelerators, adhesion agents, anti-color separation agents, anti-settling agents, and other agents normally used in anti-corrosion paints, or are mixed in appropriate amounts depending on the purpose. good.

The composition of the present invention can be prepared according to conventional methods. For example, a liquid component containing a binder and a system containing other powder components may be stored in separate containers, and the two may be mixed immediately before use. In addition, components that react with the binder (e.g., zinc alloy powder, zinc powder)
Disperse some or all of the other powder components with the liquid component containing the binder, and leave the mixture with the liquid component immediately before use. ) can be mixed together. Dispersion of liquid and powder components, roll mills, sand grind mills, and regular dispersion mills
A ball mill or the like may be used. Furthermore, in the composition thus obtained, the binder concentration may generally be 5 to 15% by weight, and the steel can be constructed by any conventional means such as air spray, airless spray, roll coater, brush, etc. It can be applied to objects and dried naturally or with hot air.

The composition of the present invention having the above-mentioned structure sufficiently exhibits its function as an anti-caking coating, and maintains anti-corrosion properties even in heated areas such as the back surface of silicon welds and the back surface of strain relief. becomes possible.

[Example 1] Next, the present invention will be specifically explained with reference to Reference Examples, Examples, and Comparative Examples. Note that parts refer to parts by weight.

Reference Example X: Manufacture of zinc alloy powder Iron powder, C
Add and melt aCl2, NaCl, KCI, etc., and perform electrolysis if necessary. Then, it is powdered using a stamp mill.
The obtained alloy powder is sieved to adjust the particle size to obtain a zinc alloy powder A-L having a particle size of -325 mesh.

The melting points shown in Table 1 are determined by differential thermal analysis (TG/1") T
Measured using A30 Daini Seikosha V). The electric potential was measured on a pellet after pelletizing zinc alloy powder and immersing it in 3% saline solution for 24 hours.

Reference Example 2 parts Manufacture of binder A) Initial hydrolysis condensate of tetraalkoxysilicate Tetraethoxysilicate) 100 parts (Nippon Full Coat Co., Ltd. "Ethyl Silicate" 2SJ) Isobutyl alcohol 50 Isopropyl alcohol 24.7 Water 16.6 0, IN hydrochloric acid], 7 1sI2. (1 part B) Hydrolyzed initial condensate of a mixture of tetraalkoxysilicate and alkyltrialfoxysilicate (tetraethoxy silicate) Silicate 281) Notyltriethoxysilicate It) 6..4 (Reagent) Isobutyl alcohol l 30 Isopropyl alcohol 1G!L9 Water Soy], 9 0.1N Hydrochloric acid 2.2 66 G, 'i part Water and hydrochloric acid removed Place the remaining ingredients in a reaction container and heat at 40°C.
Water and hydrochloric acid were added dropwise over 1 hour while stirring. After the completion of the dropwise addition, stirring is continued for 1 hour to obtain binders A and B.

The amount of active ingredient in each binder A and Bi is 15% by weight.

Examples 1 to 13 and Comparative Examples 1 to 3 Table 2: Antirust coating compositions having the formulations shown are prepared and the coating film performance is evaluated.

The test conditions were as follows: A sand-frosted steel plate was used as the test piece, and the dry film thickness was 15±2μ111 by air spray. at 61) o °C or 8 (
') tl ' After heating at C for 10 minutes and cooling, test for rust prevention J. The test was conducted according to JISK5400 salt water spray test for 240 hours, and the cross-linking state was determined according to ASTM (D6
10) by t! Determine.

The results of the second test are shown in Table 2. As is clear from the table, the composition of the present invention has excellent rust prevention properties after being heated at high temperatures.

Claims (5)

[Claims] (1) A rust-preventing paint composition characterized by containing a zinc alloy powder having a melting point higher than that of zinc and a potential less noble than iron. (2) Zinc alloy powder has 0.1≦Fe≦ in weight%
60.1≦Ca≦40.0.5≦Na≦10 and 0.
The composition according to item 1 above, which contains one or more additive elements selected from 5≦ and ≦10, and the remainder, apart from impurities, is lead. (3) The composition according to item 1 or 2 above, which contains zinc alloy powder in an amount of 20 to 95% by weight in the dry coating film. (4) The composition according to any one of items 1 to 3 above, which contains zinc powder as well as zinc alloy powder. (5) In the total amount of zinc alloy powder and zinc dust, the former is 5
The composition according to item 4 above, which accounts for at least % by weight.