JPS60133072A - Primary rust preventing coating material composition having good weldability - Google Patents

Abstract

PURPOSE:The titled composition, containing a vehicle and zinc flakes in a specific proportion, capable of giving improved weldability to a steel plate by applying to the steel plate before the working and welding, particularly gas shielding welding, and useful for large-sized steel structures, e.g. ships and plants. CONSTITUTION:A composition obtained by incorporating (A) 5-10wt%, based on the dry weight, vehicle, e.g. a partial hydrolyzate condensate to an alkyl silicate of the formula Si(OR)4 (R is ethyl, butyl or cellosolve, etc.) with (B) 15-60wt% zinc flakes, preferably containing 3wt% organic pulverizing agent, and having <=100mu maximum length, 1.5-30mu average major axis, <=5mu average thickness and >=3 aspect ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition, and more particularly to a primary anticorrosive coating composition that is applied to a steel plate before processing and provides good weldability during welding, particularly gas shield welding.

Conventionally, when constructing large steel structures such as ships, bridges, tanks, and plants, it has been necessary to prevent rust during construction, to ensure complete anti-rust coating, and to construct economically and efficiently. It is common practice to remove mill scale and rust by plasting or pickling raw materials before processing, and then apply a second anti-corrosion paint.

Conventionally used primary rust-preventing paints include polyvinyl butyral resin-phosphoric acid-based washy primer,
There are organic zinc rich paints based on organic resin such as epoxy resin and high concentration zinc dust, and inorganic zinc rich paints based on inorganic binder and high concentration zinc dust. However, organic resins such as polyvinyl butyral resin and epoxy resin decompose or burn at high temperatures, and zinc-rich paints based on high-concentration zinc dust vaporize due to the low boiling point of zinc dust, which generates gas during welding. It has the disadvantage of being prone to blowholes. In particular, in gas shield welding methods such as carbon dioxide welding, the cooling rate of the bath molten metal is faster than in coated arc welding or submersor arc welding. The drawback was that a large number of holes were generated. In recent years, the use of carbon dioxide gas welding has been increasing in the shipbuilding industry, and there has been a desire to develop a primary rust-preventing paint composition that provides good weldability during gas shield welding such as carbon dioxide gas welding.

On the other hand, when molten metal is solidified, a large number of pores are generated inside the metal, and it is well known that adding a deoxidizing agent reduces the number of pores. For this reason, attempts have been made to improve the weldability of coated arc welding and submerged arc welding by adding deoxidizing pigments to secondary anti-corrosion paints (Special Patent No. 8, 1972-22923); Even when applied to carbon dioxide gas welding, good weldability was not necessarily obtained.The purpose of the present invention is to eliminate the drawbacks of conventional primary rust preventive paint compositions, and to improve weldability, especially during gas shield welding. The object of the present invention is to provide a primary anticorrosive paint composition that provides the following properties.

As a result of intensive research to achieve this objective, the present inventors have found that, in order to reduce the occurrence of blowholes during carbon dioxide gas welding, - The present invention was achieved by discovering that it is essential to use flaky zinc.

The present invention is characterized in that it contains 5 to 20 weight percent of a color vehicle and 15 to 60 weight percent of zinc flakes on a dry basis.

As the color vehicle used in the present invention, it is desirable to use one that exhibits less loss on high-temperature ignition, and the smaller the amount used, the better the weldability will be.

As such a color vehicle, for example, argyl silica)
5l(OR)4 (in the formula, R means an ethyl group, a butyl group, a cellosolve, etc.) and, if desired, an alcohol-soluble organic resin (eg
Je +J vinyl butyral,? libinyl alcohol,
Polyacrylic acid ester, etc.) are blended and used so that the weight ratio of 5io2/organic resin solids is in the range of 10010 to 60/40.

Further, as the organic resin color vehicle, for example, epoxy resin or urethane resin can also be used.

The use of the color vehicle in the composition of the present invention is 5 to 2 times in the dry coating.
If it is in the range of 0% by weight, it is fine, if it exceeds 20% by weight, blowholes will occur frequently during carbon dioxide gas welding, and if it is less than 5% by weight, the bonding strength of the coating will be weak and it will be practically difficult to form a coating. Become.

Zinc used in the present invention is essential as a rust preventive pigment, and is used in an amount of 15 to 60% by weight on a dry weight basis, preferably 20 to 40% by weight.
He is in charge of weight. The zinc used here has a maximum length of 100μ
Below, it is necessary to use zinc flakes with an average major axis of 1.5 to 3 (Jtt), an average thickness of 5 μ or less, and an asperity coverage ratio (major axis/thickness) of 3 or more. This is to prevent corrosion and obtain a sufficient surface area.Such zinc flakes have a larger specific surface area (surface area of 8 tons per unit weight of powder) than spherical zinc powder, and close contact between particles can be maintained. It has excellent properties, making it possible to significantly reduce the amount of zinc used.Also, due to its shape, combustion due to heat input during welding takes place in a shorter time than with spherical zinc powder.
The zinc in the coating composition is completely combusted before the bath bead is cooled, and the vaporized zinc is dissipated outside the system, thereby avoiding blowholes. In addition, organic grinding agents (higher fatty acids such as stearic acid and oleic acid, or their metal salts) are used during the production of zinc flakes, but if the content of organic grinding agents in zinc flakes is high, the rust prevention properties will decrease. This tends to increase the occurrence of blowholes caused by CO2H2 and the like due to heat during welding. Therefore, it is desirable that the content of organic matter in the zinc flakes be 3 times or less. The amount of zinc flakes used is 15 to 60% by weight on a dry weight basis. 60 weight N%
If the
15 layers! -% or less, the rust prevention properties are poor.

In the present invention, in addition to the color vehicle and zinc flakes as essential components, commonly used solvents, extender pigments, coloring pigments, general antirust pigments, various additives, etc. can be added as necessary.

When the coating composition of the present invention is applied to areas from which mill scale and rust have been removed by plasting, pickling, etc., it is possible to prevent rust from forming on steel plates for a long period of time.

′! 1: Unlike conventional primary anti-rust coating compositions, welding work can be performed with high efficiency without causing many blowholes during carbon dioxide gas welding.

Hereinafter, production examples, examples, and comparative examples of the composition of the present invention will be described. In addition, parts and 忤 in the following examples mean parts by weight and weight.

Production Example 1 (Production of a color vehicle) 38 parts of ethersilicate (manufactured by Nippon Colcoat Chemical Co., Ltd., trade name [Ethersilicate 40J) and 57 parts of isopropyl alcohol were placed in a container equipped with a stirrer, mixed thoroughly, and kept at 40°C. While stirring, add Q, IN hydrochloric acid 0
．． A mixture of 5 parts and 4.5 parts of water was added dropwise over 1 hour. After dropping, continue stirring at 40°C for 5 hours, and add 5lO2
An ethyl silicate partial hydrolysis condensation solution of about 15 cm was obtained.

Production Example 2 (Production of color vehicle) Put 85 parts of isopropyl alcohol into a container equipped with a stirrer,
While stirring, 15 parts of polyvinyl butyral (manufactured by Muneki Kagaku Co., Ltd., trade name [S-LEC BL-1J) was added little by little, and the mixture was stirred until homogeneous to obtain an organic resin solution.

Ethylsilicate condensation liquid obtained in Production Example 1, Production Example 2
The organic resin solution obtained in and? Reamite resin curable epoxy resin (Epoxy resin Nigel Kagaku Co., Ltd. Epicoat 1004, polyamide resin: Fuji Kasei Co., Ltd. Tomide 215X-70 was used in a ratio of 80:20) was used as a color vehicle, and as shown in Table 1. 9 Paints were prepared to have the dry weight coating components of Examples 1 to 11 and Comparative Examples 1 to 9, and the rust prevention properties were tested by outdoor exposure, and the weldability was tested by carbon dioxide gas welding and gravity bath welding. . The results are shown in Table 1. Each test method followed the guidelines below. All values for paint components are shown on a dry weight basis.

[Rust prevention test]

A steel plate with a length of 300mm and a width of 10100mm and a thickness of 12111111 was shot blasted, coated with the coating compositions of Examples 1 to 11 and Comparative Examples 1 to 9 to a thickness of 15 to 25μ, and exposed outdoors for 4 months. ASTM-
D610/5SPC-VIs217) Rust occurrence standard plate was compared and evaluated. The evaluation criteria were as follows: ASTM scores of 9' or higher are ◎, 7 to 8 points are ○, 5 to 6 points are Δ, 3 to 4 points are ×, and 2 or less points are XX.

[Welding test]

Vertical 5001111+! , width j5Qm, thickness 161111
The steel plate of No. 1 was shot blasted, and Examples 1 to 1 were applied to it.
1. The coating compositions of Comparative Examples 1 to 9 were applied to a thickness of 15 to 25μ, dried for 7 days, and then tested in Test Example 1.2 below.
A welding test was conducted. Judgment was made by X-ray welding inspection as specified in JIS Z 3104.

(An example of a test.

A horizontal fillet welding test was conducted using a welding rod MG50D (manufactured by Kobe Steel, Ltd.) using a carbon dioxide shielded arc welding method.

(2) Test Example 2 A horizontal fillet welding test was conducted using the gravity welding method using the welding rod Zerode 27 (manufactured by Kobe Steel, Ltd.). As is clear from the results in Table 1, this By using the coating composition of the invention, blowholes are extremely less likely to occur during carbon dioxide gas welding and gravity welding, and rusting of steel sheets can be prevented for a long period of time.

Claims (3)

[Claims] (1) A primary anticorrosive paint composition with good weldability, characterized by containing 5 to 20% by weight of a color vehicle and 15 to 60% by weight of zinc flakes on a dry weight basis. (2) The primary defense according to claim 1, wherein the zinc flakes have a maximum length of 100'tr or less, an average major axis of 1.5 to 30μ, an average thickness of 5μ or less, and an aspect ratio (major axis/thickness) of 3 or more. Rust paint composition. (3) The primary anticorrosive coating composition according to claims 1 and 2, wherein the zinc flakes contain an organic pulverizing agent used in the production of zinc flakes in an amount of 3% by weight or less.