JPS5844628B2 - Inorganic paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inorganic coating composition containing a water-soluble polyvalent metal phosphate compound as a binder.

More specifically, (A) water-soluble polyvalent metal phosphate compounds, (B) hydroxides of polyvalent metals soluble in phosphoric acid, (C) complex oxides containing iron oxide as a main component, and The present invention relates to an inorganic coating composition made of refractory powder and particularly suitable for coating metal plates such as iron, aluminized steel plates, and aluminum.

Conventionally, a composition comprising a water-soluble polyvalent metal phosphate compound (A) as a binder and a transition metal oxide to be fired as a hardening agent is mixed with the binder (Japanese Patent Publication No. 48-3196
Publication No. 9).

However, when this composition is applied to metals such as iron, aluminum, and aluminized steel plates, the coating film becomes porous and cracked due to reactions and other factors, resulting in disadvantages such as poor adhesion.

The purpose of the present invention is to overcome the above-mentioned drawbacks of inorganic paints, and based on this point of view, the present inventors conducted extensive research and found that (A) water-soluble polyvalent metal phosphorus An inorganic coating composition consisting of an acid salt compound, a hydroxide of a polyvalent metal soluble in (B) acid, a complex oxide containing iron oxide as a main component (Q), and a refractory powder (D),
The inventors have discovered scales that can form good coatings on iron plates, aluminized steel plates, aluminum plates, etc., and have completed the present invention.

That is, the present invention provides (A) general formula MiOj-XP205.yH20 (wherein M is a metal, i
, j is a positive integer determined by the valence of metal M, or 1 to
4, y indicates 0 or a positive number.

) Water-soluble polyvalent metal phosphate compounds 10 to 20
Weight %, (B) Polyvalent metal hydroxide soluble in phosphoric acid 1~
10% by weight, (Q3 to 30% by weight of a composite oxide containing iron oxide as a main component) and 40 to 86% by weight of (D refractory powder) can be applied well to iron plates, aluminized steel plates, aluminum plates, etc. Another object of the present invention is to provide an inorganic paint composition that has a long pot life.

The water-soluble polyvalent metal phosphate compound (A) of the present invention is used as a binder and has the general formula MiOj-x
P205・yH20 (where M is metal, i, j are metal M
A positive integer determined by the valence of , or 1 to 4, and y represents O or a positive number.

) and can be used alone or as a mixture of two or more.

Examples of such water-soluble polyvalent metal phosphate compounds include water-soluble phosphate compounds of aluminum, calcium, magnesium, zinc, iron, etc., and monobasic aluminum phosphate is preferably used.

Of course, these phosphates may be used in the form of an aqueous solution or in the form of a powder and mixed with water at the time of use.

It is a member of the constituent components of the inorganic coating composition of the present invention (B
)! A part of the hydroxide of polyvalent metals soluble in phosphoric acid reacts with the phosphoric acid component during paint mixing at room temperature, resulting in (A
) At the same time, it suppresses the reaction between the water-soluble polyvalent metal phosphate compound and the metal base material, and at the same time, the remaining hydroxide reacts with the phosphoric acid component during heat curing. Moreover, it provides a coating film with good water resistance.

Such hydroxides include hydroxides of polyvalent metals such as aluminum, iron, manganese, magnesium, and calcium, and aluminum hydroxide is particularly preferably used.

A member of the constituent components of the inorganic coating composition of the present invention (Q
The composite oxide containing iron oxide as a main component is used as a hardening agent like the polyvalent metal hydroxide (B) above, and reacts moderately with the water-soluble polyvalent metal phosphate compound, and is suitable for iron plates, It provides a coating film with excellent adhesion to aluminum-treated steel sheets, aluminum sheets, etc.

The reason why a coating film with excellent adhesion can be realized by adding the complex oxide is not clear, but the reaction between the binder and the metal substrate to be coated is caused by the reaction with the phosphoric acid component, similar to (B) polyvalent metal hydroxide. In addition to the effect of suppressing the unfavorable reactions of (
B) Compared to polyvalent metal hydroxides, the reactivity with the phosphoric acid component at low temperatures is low, so the phosphate binder does not undergo rapid gelation, and the phosphate binder does not easily gel during heat curing. In order to exhibit sufficient reactivity accompanying dehydration condensation,
It is expected that it will provide an inorganic paint with excellent adhesion, surface hardness, etc. and a long pot life.

That is, it is expected that a combination of two types of curing agents with different reactivities will provide an excellent inorganic coating film.

The other component to create such a composite oxide containing iron oxide as a main component is a metal oxide that forms a ferrite compound, solid solution, etc. with iron oxide and can control the reactivity with phosphoric acid. , manganese, cobalt, chromium, tin, molybdenum, titanium, etc., and iron-manganese and iron-tin composite oxides are preferably used.

Iron oxides such as triiron tetroxide and ferric oxide alone can be used as a hardening agent for water-soluble polyvalent metal phosphates, but in this case, it is difficult to control the mixing ratio, the pot life is short, and the adhesion is poor. It has defects such as poor performance and easy formation of foam and cracks in the coating film.

Composite oxides can be prepared by mixing and firing each oxide, or by firing a hydroxide coprecipitated from a water-soluble metal salt, but the coprecipitation method is preferable in terms of uniformity. used.

The mixing ratio of iron oxide and other oxides may be arbitrarily changed depending on the required reactivity, etc., but preferably the iron oxide component converted to Fe2O3 in the composite oxide is 40 to 40%.
It is mixed so that it accounts for 80% by weight.

If it is less than 40% by weight, the effect as a curing agent will be reduced, requiring a large amount to be added, which is not economical, and
If it exceeds 0% by weight, disadvantages such as shortened pot life and reduced adhesion will occur, which is not preferable.

Further, the firing temperature of the composite oxide varies depending on the composition, but is generally about 400 to 1300°C.

4C) If the temperature is below 0°C, the activity will be too strong, resulting in disadvantages such as shortened pot life and reduced adhesion.If the temperature is above 1300°C, it will not be economically advantageous and post-processing such as crushing will be required. This is not preferable because it becomes difficult.

Further, after firing, a portion of each individual oxide may remain, but this can be dealt with by appropriately changing the amount added, considering the activity as a hardening agent.

The zero-resistant powder, which is one of the constituent components of the inorganic coating composition of the present invention, is used as a filler to impart excellent hardness, adhesion, and heat resistance, and also as a binder (A) water-soluble polyvalent It is mixed as a path-forming agent for releasing the gas generated by the reaction between the metal phosphate compound and the metal.

As such refractory powder, refractory powder with low reactivity with phosphoric acid is used, such as quartz, alumina,
Examples include crushed products of mullite, zirconia, zirconium silicate, various glass powders, glass fibers, and ceramic fibers.

Although the particle size of these powders is not particularly limited, those of about 1 to 50 μm are usually preferably used.

If it is less than about 1μ, the coating film becomes too dense, which tends to cause foaming during heat curing and cracks due to drying shrinkage.
If it exceeds 0μ, there is a tendency for problems such as the coating film becoming rough and difficulty in working with a spray gun.

Of course, if surface roughness is required, it is also possible to add a small amount of large particles such as sand.

In producing the inorganic coating composition of the present invention, (A) a water-soluble polyvalent metal phosphate compound, (B) a hydroxide of a polyvalent metal soluble in phosphoric acid, (mainly composed of q iron oxide), The mixing ratio of the composite oxide and refractory powder is generally approximately 10 to 20% by weight, preferably 12 to 17% by weight (as solid content) of (A) water-soluble polyvalent metal phosphate compound; (B) The polyvalent metal hydroxide is about 1 to 10% by weight, preferably 2 to 5% by weight.
, (composite oxide containing q iron oxide as a main component is about 3 to 3
0% by weight, preferably 5-20% by weight and p) refractory powder about 40-86% by weight, preferably 60-75% by weight.

(A) If the mixing ratio of the water-soluble polyvalent metal phosphate compound is less than 10% by weight, the adhesion of the coating film will decrease, cracks will easily occur (in addition, the pot life will be shortened, On the other hand 2
If it exceeds 0% by weight, it is not preferable because it tends to cause foaming and cranking in the coating film, resulting in a decrease in adhesion.

In addition, (B) "If the mixing ratio of the hydroxide of a polyvalent metal soluble in hydrogen acid is less than 1% by weight, the addition becomes virtually meaningless, and foaming is likely to occur when applied to a substrate. On the other hand, if it exceeds 10% by weight, the pot life will be shortened and the adhesion will be reduced.

This is undesirable because it causes problems such as cranking.

In addition, if the mixing ratio of the complex oxide containing (q) iron oxide as the main component is less than 3% by weight, it will be impossible to suppress the reaction between the phosphate and the metal substrate, and the coating film will tend to foam. On the other hand, if it exceeds 30% by weight, it is undesirable because it causes disadvantages such as a short pot life, a decrease in adhesion, and a tendency to crack.

In addition, if the mixing ratio of (I) refractory powder is less than 40% by weight, the absolute amount as a filler to the binder will decrease, making it more likely to cause foaming during curing and, in addition, more likely to cause cracks. If it exceeds % by weight, the binder component is relatively reduced, resulting in disadvantages such as decreased adhesion and easy cracking, which is undesirable.

As other auxiliary agents, clays such as bentonite are added as filler anti-settling agents, high-boiling substances such as glycerin and ethylene glycol are added as drying retardants and leveling agents, and various surfactants are added as adhesion improvers. It is also possible.

The inorganic coating composition of the present invention has the above-mentioned (B)! By mixing and dispersing a polyvalent metal hydroxide soluble in J acid, a composite oxide containing iron oxide as a main component, and a refractory powder into a water-soluble polyvalent metal phosphate aqueous solution, If necessary, it is also possible to mix a powder obtained by drying and condensing a water-soluble polyvalent metal phosphate compound and disperse it by adding water at the time of use.

As a method for mixing the mixed composition, any known mixing method such as a ball mill, attritor, stirrer, stirrer, etc. can be used.

As a method for applying the inorganic coating composition of the present invention to a substrate, known coating methods such as spraying, brushing, roller, dipping, etc. can be employed.

The applied inorganic coating composition is generally heated to 200°C or higher,
It is preferably heated and cured at a temperature range of about 250 to 350° C. for 10 minutes or more, thereby forming a coating film with excellent water resistance, weather resistance, heat resistance, adhesion, smoothness, hardness, etc.

In addition, the inorganic coating composition of the present invention has good adhesion to various substrates, such as ceramic materials such as glass, ceramics, and bricks, and metal materials such as iron, aluminum, stainless steel, and nickel. It can be used extremely effectively as a paint for materials, and it has the characteristic that it can be applied to aluminum-treated steel plates, etc., which were difficult to coat with conventional silicate-based inorganic paints.

As described in detail above, the inorganic coating composition of the present invention has a coating film that can be obtained on a metal base material, compared to conventionally proposed systems consisting of water-soluble phosphate-transition metal oxides. It has excellent adhesion, hardness, and heat resistance, and has a long pot life.

The method of the present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Note that parts and percentages in the examples are based on weight.

In the following examples, the physical properties of the coating film were measured by the following method.

Coating film appearance: Cracks and foaming were observed with the naked eye and with a magnifying glass.

Hardness: Pencil hardness was measured according to JISK-5400.

Boiling water resistance: The state of the coating film was observed after being immersed in boiling water for 3 hours.

Steam resistance: The coating film is exposed to steam at 100℃ for 8 hours☆☆
After that, the surface condition was observed. Adhesion: Cellotape was placed on the coating film, rubbed strongly and then peeled off, and the presence or absence of peeling of the coating film was observed.

Example 1 A water-soluble polyvalent metal phosphate compound aqueous solution, a polyvalent metal hydroxide soluble in phosphoric acid, a composite oxide containing iron oxide as a main component, a refractory powder, and water for viscosity adjustment were prepared. Mixed and ball milled for 1 hour.

Approximately 1,500 cp of the thus obtained coating composition was applied to iron and aluminized steel plates using a spray gun.
The coated article was cured by heating at 00° C. for 30 minutes to obtain a coated article.

The thickness of the coating film was approximately 100μ. Table 1 shows the coating composition, and Table 2 shows the physical properties of the coating film.

From Tables 1 and 2, the coating composition of the present invention (Experiment & 1~
It is clear that 5) forms an excellent coating film and that compositions outside the scope of the present invention (Experiments A6 to 13) do not provide satisfactory coating films compared to the composition of the present invention. be.

The composition of Experiment A3 formed a good coating film even one month after mixing, and exhibited a long pot life.

Claims (1)

[Claims] 1(A) General formula MiOj -XP205·yH20 (wherein M is a metal, i and j are positive integers determined by the valence of the metal M, or 1 to 4, and y is O or a positive 10 to 20 water-soluble polyvalent metal phosphate compounds represented by
Weight% (solid content equivalent), (B) 1 to 10% by weight of polyvalent metal hydroxide soluble in phosphoric acid, (3 to 30% by weight of complex oxide containing q iron oxide as a main component, and (An inorganic coating composition consisting of 40 to 86% by weight of 'f3 refractory powder, and further containing adjuvants as necessary. 2(A) The water-soluble polyvalent metal phosphate is composed of primary phosphoric acid The inorganic coating composition according to claim 1, which is an aluminum aqueous solution. 3(B) The inorganic coating composition according to claim 1 or 2, wherein the polyvalent metal hydroxide is aluminum hydroxide. Composition. 4 (Inorganic paint according to claim 1, 2 or 3, wherein the composite oxide containing C1 iron oxide as a main component is a composite oxide consisting of ferric oxide-manganese oxide) Composition.