JPS61101565A - Inorganic paint - Google Patents

Abstract

PURPOSE:To obtain the titled paint which has excellent corrosionproofness, heat resistance and film-forming properties, little causes formation of white rust and reduces the number of priming steps, consisting of an Al alloy powder mainly composed of three components of Al, Si and Zn or a mixture thereof with Zn powder and a vehicle. CONSTITUTION:A particulate and/or flaky Al alloy powder (A) having an average particle size of 25mu or below, mainly composed of three components of 40-80wt% Al, 15-30wt% Si and 2.3-40wt% Zn or a mixture (A') of component A and 20-150wt% (based on the quantity of component A) Zn powder, and at least one vehicle (B) selected from among an alkyl silicate, an alkali silicate and colloidal silica are mixed together to obtain an inorg. paint which can be used as a shop coat primer which gives a coating film contg. 20-95wt% component A or A'.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention is a shop primer (steel pre-treatment paint) that has excellent heat resistance and anti-corrosion properties in steel processing processes for ships, offshore structures, plants, bridges, land tanks, etc. ) related to inorganic paints used as

(Prior Art) Conventionally, various types of paints have been used as shop primers, and currently, inorganic zinc paints are used for ships, offshore structures, plants, etc. due to their excellent corrosion resistance and heat processability. It has become mainstream as a shop primer.

(Problems to be Solved by the Present Invention) However, inorganic zinc paints often use zinc dust as a coating film forming material, but since the melting point of zinc is 419°C, it is heat resistant to over 400°C. Poor temperature, 400℃
Since the above causes paint film defects such as peeling of the paint film, discoloration due to oxidation of zinc, and a decrease in corrosion resistance, it is desired to develop a shop primer that can withstand even higher temperatures.゛Also, if the inorganic zinc paint film is left as it is, zinc compounds (white rust) will be generated due to the oxidation of zinc, and this white rust will be the cause of inhibiting the adhesion of the top coat when applying the top coat. It also becomes.

Therefore, an object of the present invention is to provide an inorganic paint with significantly improved heat resistance and corrosion resistance.

(Means for Solving the Problems) The present inventor focused on metal powders that have a higher melting point than zinc, and as a result of examining metal powders that are reactive with the coloring agent (silicate), the inventor found that Al-Si - When using aluminum alloy powder mainly consisting of the three components Zn, film-forming properties are also good,
It was discovered that a paint with good heat resistance and corrosion resistance can be obtained.

This is because the inclusion of 3i in AIl increases the melting point and improves heat resistance, and at the same time, Zn in the alloy reacts with the silicic acid valve (Si 02 ) in the color spreader to form a coating film.

This is clear from the fact that when AX-S+gold alloy is used, the heat resistance is good, but the film forming property is poor because there is no reaction with the coloring agent.

Regarding aluminum alloys, the use of Aρ-7n alloy powder in paints has already been introduced, but it does not improve heat resistance.

The feature of the present invention is that AJ! It consists of a mixture of aluminum alloy powder consisting mainly of the three components -Si-Zn, alone or in a mixture with zinc powder, and a coloring agent.

In this way, aluminum alloy powder is Al-3i-Zn
The ratio of these three components is AJ is 40 to 80% (
weight, hereinafter the same type) preferably 50 to 72%, 3i is 15
~30% preferably 15-21%, 7n is 2.3-40
% preferably within the range of 10-31%.

If the composition of this alloy is outside this range, it will be unfavorable to achieve the object of the present invention. In other words, if the Aj content is less than 40%, the heat resistance and corrosion resistance after heat resistance will be extremely poor.
Moreover, if this exceeds 80%, film-forming properties and anticorrosion properties decrease. Also, if 3i is less than 15%, the heat resistance will be poor.
If this exceeds 30%, it becomes difficult to produce a stable alloy. Furthermore, if the Zn content is less than 2.3%, film-forming properties, corrosion resistance and weather resistance will be extremely reduced;
If it exceeds this value, heat resistance and corrosion resistance after heat resistance will be poor.

Furthermore, the aluminum alloy is used alone or in combination with zinc powder in an amount of 20 to 95% in the coating film, thereby providing an anticorrosive coating film with excellent heat resistance.

Next, Table 1 shows the composition of the aluminum alloy powder used in the paint of the present invention. When using aluminum alloy alone, it is desirable to have a zinc content (6) of 10% or more from the viewpoint of corrosion resistance, but when used together with zinc powder, there is no practical problem if the zinc content in the alloy is 2.3% or more. .

The shape of the aluminum alloy powder may be granular, flake, or a mixture of both.

When aluminum alloy powder and zinc powder are used together, the mixing ratio of zinc powder to the alloy powder can range from 20 to 150%, but preferably from 20 to 100%. If the ratio of zinc powder to the alloy powder is 150% or more, the heat resistance will not improve, and if it is less than 20%, the long-term corrosion resistance will decrease.

Further, the particle size of the alloy powder is suitably 25μ or less, and if it exceeds 40μ, there will be problems in coating workability and film-forming effect when forming a thin film.

As the coloring material, alkyl silicates, alkali silicates, colloidal silicate, etc., which are generally used as inorganic paint materials, can be selected.

Further, in order to improve painting workability, a small amount of organic resin such as polyvinyl butyral resin may be added.

(Effects of the present invention) When the paint of the present invention is used as a shop primer,
There is little burn-out deterioration of the paint film after heat treatment such as welding, fusing, or distortion removal work in the processing process of steel plates, and the occurrence of white rust is significantly reduced even in general white rust, so the burn-out deterioration of the paint film is reduced when applying the top coat. Also, there is no need to remove white rust, and the number of steps required for surface treatment can be significantly reduced.

In addition, since there is less heat loss due to gasification during welding, there are fewer defects in welded parts such as bits and blowholes.

(Example) Using the alloy powder shown in Table 1, paints of each formulation example (Table 2) were prepared. A dry film thickness of 20 μm was applied to one side of a steel plate (70 x 150 x 2.3 mm) side-blasted with each of the prepared paints.
(2) Corrosion resistance (paint film after 500 hours of oxidation in 5% salt water spray at 35°C) (3) Heat resistance (6)
After being left in the oven at 00°C and 700°C for 1 hour, the condition of the coating film was investigated. (4) Weather resistance (vacuumed outdoors at 45 degrees south and inspected the paint film after 3 months) The above test results are shown in Table 3. As is clear from this table, the paint of the present invention has better corrosion resistance, less occurrence of white rust, and improved heat resistance than the inorganic zinc paint of the comparative example.

When a certain hue is required, a part of the aluminum alloy powder or zinc dust is replaced with a commonly used xfla material or organic pigment.

Table 1 Aluminum alloy examples 11')-1 bite 11νer@(Warm hanging %) Table 2-2 Table 2-3 Table 2-4 Table 3-1 Coating film performance test results

Claims (6)

[Claims] (1) An inorganic paint made of an aluminum alloy powder consisting mainly of the three components Al-Si-Zn alone or in a mixture with zinc powder and a color vehicle. (2) In claim 1, the structure of the aluminum alloy powder is 40 to 80% Al (by weight, the same applies hereinafter).
, Si is in the range of 15 to 30%, and Zn is in the range of 2.3 to 40%. (3) The inorganic paint according to claim 1, wherein the aluminum alloy powder has an average particle size of 25 μm or less. (4) The inorganic paint according to claim 1, characterized in that the paint film contains 20 to 95% of aluminum alloy powder. (5) The inorganic paint according to claim 1, characterized in that the mixing ratio of zinc powder to aluminum alloy powder is in the range of 20 to 150%. (6) The inorganic paint according to claim 1, wherein the coloring agent is at least one selected from alkyl silicate, alkali silicate, and colloidal silica.