JPH05339521A - Inorganic zinc shop primer composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which sufficiently functions as a primary anticorrosive paint and gives a good coating film having excellent weldability and few pits or blow-holes. CONSTITUTION:The title composition comprises a precondensate of a silicic ester, a zinc powder (a), and a molybdate pigment (b), the contents of the components (a) and (b) each being 20-60wt.% on a dry basis.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a primary anticorrosive paint for steel materials. More specifically, the present invention relates to an inorganic zinc shop primer composition which is applied to a steel sheet before processing and imparts excellent welding performance during welding.

[0002]

2. Description of the Related Art Conventionally, in the construction of large steel structures such as ships, bridges, tanks, plants, etc., a primary rust preventive primer has been used for the purpose of temporarily preventing rusting of steel plates during the construction period such as processing and assembly. It is painted. What is required of this primary anticorrosive paint is that it has corrosion resistance (exposure) of 6 months or more, excellent top coatability, and good weldability. From these facts, zinc primer with binder of silicate initial condensate blended with butyral resin and inorganic zinc rich primer containing high concentration of zinc powder (80% by weight or more in dry coating film) have become mainstream. ing.

[0003]

In recent years, manufacturers of large steel structures such as ships, bridges, tanks and plants have
Welding automation has been promoted from the viewpoint of labor shortage and efficiency improvement, and carbon dioxide shield arc welding and the like are applied. However, the zinc primer that uses the silicate ester initial condensate blended with the butyral resin described above as a binder is affected by the gas of the organic components in the binder, and the inorganic zinc rich primer that contains zinc powder in a high concentration is zinc powder. However, since hydrogen gas is taken in during vaporization, there is a drawback that pits and blow holes are likely to occur in the welded part.

[0004]

Means for Solving the Problems The present inventor has conducted diligent research for the purpose of developing an inorganic zinc shop primer in which these pits and blow holes are not generated during welding. By using these together, an inorganic zinc shop primer composition having good weldability was developed without impairing the characteristics of conventional zinc primers.

According to the present invention, a silicate ester initial condensate, zinc powder, and a molybdenum-containing pigment are essential components, and the dry coating film contains 20 to 60% by weight of zinc powder and 20 to 60% by weight of a molybdenum-containing pigment. An inorganic zinc shop primer composition having good weldability characterized by the above.

The silicic acid ester initial condensate used in the present invention is a binder component, and a monomer such as tetraalkoxysilicate, for example, tetramethoxysilicate, tetraethoxysilicate, tetrapropoxysilicate, tetraisopropoxysilicate, tetrabutoxysilicate, etc. Alternatively, it is a reaction product obtained by subjecting a partial condensate to a condensation reaction in the presence of a catalyst such as water and an acid such as hydrochloric acid, sulfuric acid, nitric acid and acetic acid. The zinc powder used in the present invention may be a commercially available product, but preferably has an average particle size of 5 to 1
5 μm is good. Zinc dust is added to the dry coating film in an amount of 20 to 60% by weight, preferably 30 to 50% by weight. Compounding amount is 2
If it is less than 0% by weight, good antirust property cannot be obtained, and if it exceeds 60% by weight, weldability is deteriorated, white rust is often generated, and adhesion to the top coat is also deteriorated. In the present invention, a molybdenum-containing pigment is used as a pigment used in combination with zinc powder to improve weldability. Typical molybdenum-containing pigments include zinc molybdate and aluminum molybdate. Further, since they also have an action as a rust preventive pigment, the amount of zinc powder blended can be reduced. 20 molybdenum-containing pigments in dry coating
-60% by weight, preferably 30-50% by weight.
If the blending amount is less than 20% by weight, good weldability cannot be obtained,
On the other hand, if it exceeds 60% by weight, the rust preventive property is deteriorated. In the inorganic zinc shop primer composition of the present invention, in addition to the above essential components, a binder is an inorganic resin such as colloidal silica, a pigment is used for the flux of the welding rod, for example, ferromanganese or the like and generally in paints. Extending pigments used, for example, clay, mica, talc, etc., coloring pigments as required, usual alcohol as a solvent, for example, methanol, ethanol, isopropyl alcohol, ethers such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, etc., Aromatic hydrocarbons, for example, xylene, toluene, etc., as well as additives and the like can be blended according to the purpose. The composition of the present invention can be prepared by a conventional method for producing a general paint. For example, the liquid component containing the binder and the powder component other than the binder may be stored in separate containers and mixed immediately before use. Then, it may be applied to the steel plate by a usual coating means such as airless spray, air spray, brush or the like and dried.

[0007]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The term "parts" means "parts by weight". Binders manufacturing tetraalkoxy precondensate * 50 parts 0.1N aqueous hydrochloric acid solution 1 parts Water 6 parts Ethanol 43 parts Total 100 parts of silicate * "Ethyl Silicate 40" (40% solids) Product Name manufactured by Tama Chemical Co., Ltd. Put the remaining components excluding hydrochloric acid and water into the reaction vessel and keep at 40 ° C.
Keeping at, and add hydrochloric acid and water dropwise over 1 hour while stirring. After completion of the dropping, the mixture was stirred for 2 hours while maintaining the temperature at 40 ° C. to obtain a binder component. Next, an inorganic zinc shop primer composition was prepared according to a conventional method with a formulation corresponding to the examples shown in Table 1 and a comparative example shown in Table 2. After sufficiently stirring, the viscosity was adjusted with isopropyl alcohol, and the mixture was sprayed with air. Painted.

[0008]

[Table 1]

[0009]

[Table 2]

Test method For rust prevention, a 3.2 × 70 × 150 mm sandblasted steel plate was used, each primer composition was coated to a dry film thickness of 15 μm, and naturally dried at 25 ° C. for 72 hours, followed by a salt spray test. (JIS5400 9.1) Conducted for 240 hours,
The generation state of rust was investigated. The evaluation standard is ASTM D-6
The rust generation standard of 10 was followed. Weldability test is 12 × 150
A steel plate (SM50A) having a size of 1000 mm was shot blasted, each primer composition was applied so as to have a dry film thickness of 15 μm, and naturally dried for 7 days, and then the following test conditions were applied. Test conditions (Coated arc welding) Welding rod LTB-50 (manufactured by Kobe Steel, Ltd.) Rod ratio 1.3 Weld shape Horizontal fillet welding test conditions (carbon dioxide shielded arc welding) Welding rod MX-200 ((stock) ) Kobe Steel Co., Ltd.) Welding speed 60 cm / min Welding shape Horizontal fillet welding Pit and blow hole generation were investigated on the second bead. The blowhole occurrence rate was measured by forming the fracture surface of the second bead and measuring the blowhole defect rate (area rate) by an image analyzer. The coating film performance and welding test results are shown in Tables 3 and 4.

[0011]

[Table 3] Pit: Indicates the number of occurrences. (Pieces) Blowhole: Shows the blowhole occurrence rate. (%)

[0012]

[Table 4] Pit: Indicates the number of occurrences. (Pieces) Blowhole: Shows the blowhole occurrence rate. (%) As is clear from the above, the composition of the present invention has a rust prevention test,
Excellent results were obtained in both weldability tests.

[0013]

EFFECTS OF THE INVENTION The composition of the present invention provides a good inorganic zinc shop primer coating film capable of sufficiently exhibiting the function as a primary anticorrosive paint and having excellent weldability and having very few pits and blow holes. Can be provided.

Claims (1)

[Claims] 1. A dry coating film containing 20 parts of zinc powder containing a silicate ester initial condensate, zinc powder, and a molybdenum-containing pigment.
~ 60 wt%, molybdenum-containing pigment 20-60 wt%
An inorganic zinc shop primer composition containing the same.