JP2007327000A - Inorganic coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inorganic coating composition forming a coating film having toughness and rust prevention power. <P>SOLUTION: The inorganic coating composition is obtained by mixing an alkali metal silicate with calcium silicate or zinc phosphate, natural glass as an inorganic filler in scaly fine powder having an average particle diameter of ≤30 μm, which comprises colemanite or ulexite as a main component, has an eluting action on diboron trioxide component and a tripolyphosphate so as to combine a tripolyphosphate ion with free iron ion and zinc ion derived from a coated material, forming a chelate complex and passivating free metal ions causing rust so as to control the occurrence of rust. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inorganic coating composition capable of obtaining a coating film that is tough and excellent in rust prevention.

Conventionally, many kinds of inorganic coating compositions using alkali metal silicate as a binder have been known, but most of them are brittle and the resulting coating is brittle, for example, the object to be coated expands or contracts due to temperature changes. Then, fine cracks were generated in the coating film due to distortion, and the weather resistance and stain resistance of the coating film were impaired.
Therefore, in order to solve this problem, the inventors of the present application add a polyvalent metal-containing curing agent such as calcium silicate and zinc phosphate to the alkali metal silicate, and further, as an inorganic filler, the main component is colemanite, urexite, etc. An inorganic coating composition was invented in which a fine powder of natural glass having a boric acid component eluting action was mixed (see Patent Documents 1 and 2).
In this product, boric acid is eluted by mixing with water, and when this mixed solution is applied and dried, the eluted boric acid solidifies as the binder hardens, and a tough coating film can be obtained. Due to its excellent durability, weather resistance and stain resistance, it has been widely recognized as a film-forming agent for protecting the surface of general building interior and exterior materials and underground passage interior materials.

Japanese Patent No. 3140611 (Claims) Japanese Patent No. 3140612 (Claims)

  And although patent document 1 and 2 invention goods were very popular among consumers, in recent years, the burden to the exterior articles by acid rain has increased more and more, therefore, strengthening of the rust prevention action has been desired. .

  In view of the above problems, the present invention is a natural glass having an action of eluting diboron trioxide, containing calcium silicate or zinc phosphate added to an alkali metal silicate and containing, as an inorganic filler, colemanite or urexite as a main component. Is mixed as a scaly fine powder with an average particle size of 30 μm or less, and tripolyphosphate is combined to form a chelate complex by combining tripolyphosphate ions with free iron ions and zinc ions derived from the coating. Then, the above-mentioned problems are solved by passivating free metal ions that cause rust generation to suppress the generation of rust.

In short, the present invention is the addition of calcium silicate or zinc phosphate to an alkali metal silicate, and as an inorganic filler, a natural glass having an elution action of a diboron trioxide component, which is mainly composed of colemanite or urexite, has an average particle diameter. Since it was mixed as flaky fine powder of 30 μm or less and further tripolyphosphate was blended, a chelate complex was formed by tripolyphosphate ions derived from tripolyphosphate and free iron ions and zinc ions derived from the object to be coated. , The generation of rust can be suppressed.
Therefore, by applying the product of the present invention to various articles used outdoors, the product can be protected from rust caused by acid rain, and durability can be improved.
In addition, since the coating film has super hydrophilicity, even if dirt is attached to the coating film, it can be self-purified only by being exposed to rain water.

  Since fine sericite with an average particle size of 30 μm or less is blended, the surface of the coating film can be made smoother, the adhesion state of the deposits on the surface can be weakened, and the above-mentioned self- The purification action can be improved.

  5 to 70 parts by weight of calcium silicate or zinc phosphate, 5 to 200 parts by weight of flaky fine powder of natural glass, 1 to 25 parts by weight of tripolyphosphate, 100 parts by weight of alkali metal silicate, finely powdered sericite 10 to 30 parts by weight, the practical effects such as being able to combine rust prevention power, toughness, weather resistance, and contamination resistance in a well-balanced manner are significant.

Hereinafter, an embodiment of the present invention will be described.
The inorganic coating composition according to the present invention is basically obtained by adding calcium silicate or zinc phosphate to an alkali metal silicate and eluting with diboron trioxide as a main component, including colemanite or urexite. Natural glass having an action is mixed as a flaky fine powder having an average particle size of 30 μm or less, and tripolyphosphate is further blended.
Moreover, you may mix | blend fine powdery sericite (sericite) with the said composition, and the coating-film surface can be made smoother by addition of fine powdery sericite.

  Alkali metal silicates are ant-kari metal silicates such as lithium silicate, sodium silicate, potassium silicate, etc., and by adding calcium silicate or zinc phosphate, dehydration shrinkage reaction and gelation reaction Occurs and solidifies.

And colemanite _{(2CaO · 3B 2 O 3 ·} 5H 2 O), ulexite _{(Na 2 O · 2CaO · 5B} 2 O 3 · 16H 2 O) is a natural mineral vitreous, just immersed in water, the three containing When the diboron oxide (B ₂ O ₃ ) component is eluted and finely pulverized, the diboron trioxide component is further easily eluted, and the finely pulverized product has a scaly shape.

In the present invention, the tripolyphosphate is used to secure tripolyphosphate ions (P ₃ O ₁₀ ⁵⁻ ) in the composition and donate them to the free metal ions derived from the coating. Is not particularly limited, but sodium tripolyphosphate and aluminum tripolyphosphate are desirable from the viewpoint of availability and stability.

The colemanite, urexite, and sericite preferably have an average particle size of 30 μm or less as much as possible in terms of increasing the elution amount of the diboron trioxide component and improving the smoothness of the resulting coating film, but this range is not necessarily limited. .
The average particle diameter is a median diameter value obtained by a laser scattering particle size distribution measuring apparatus.

As a ratio of each component with respect to 100 parts by weight of the alkali metal silicate, when calcium silicate or zinc phosphate is less than 5 parts by weight, solidification of the coating film is insufficient, and when it exceeds 70 parts by weight, solidification is excessively fast. As a result, fine cracks occur in the coating film, so the ratio of calcium silicate or zinc phosphate is preferably in the range of 5 to 70 parts by weight.
In addition, when the amount of colemanite or urexite is less than 5 parts by weight, the amount of elution of the diboron trioxide component is small, the resulting coating film is brittle, and sufficient hydrophilicity cannot be obtained. Since no further improvement in coating strength and hydrophilicity is observed, the ratio of colemanite or urexite is preferably in the range of 5 to 200 parts by weight.
Further, when the tripolyphosphate is less than 1 part by weight, the effect of improving the rust-preventing power is not recognized, and when it exceeds 25 parts by weight, no further improvement is recognized. A range of 25 parts by weight is good.
And sericite is the range which 1-30 weight part affects the smoothness of a coating film, and is a suitable quantity.
In addition, the range of each said mixture ratio is the value obtained by various tests.

Next, the effect | action of the inorganic coating composition of this invention is demonstrated.
Since the inorganic coating composition of the present invention contains a tripolyphosphate, when it is mixed with an appropriate amount of water and applied to an object to be coated, the dissociated and generated tripolyphosphate ions cause rust generation. It chemically reacts with metal ions such as iron ions and zinc ions derived from the coating to form a chelate complex, and the free metal ions become passive in the coating (particularly near the interface between the coating and coating). Thus, it can no longer be converted to oxide by oxygen in the air, and rust generation is suppressed.

  Incidentally, since colemanite and urexite contain a large amount of diboron trioxide component and have the property of easily eluting diboron trioxide component in water, at the same time as mixing with the above water, from colemanite or urexite. The elution of diboron trioxide component occurs, and after coating and drying, the diboron trioxide component solidifies and vitrifies, producing a strong coating film and more firmly adhering the coating film to the object to be coated. In addition, since the diboron trioxide glass has hydrophilicity, the coating film also has hydrophilicity, and the interfacial tension between the coating film and water in contact therewith is reduced, so that dirt and coating adhered to the coating film can be obtained. Water easily penetrates between the membranes, and deposits are easily peeled off.

  Next, the present invention will be described in more detail with reference to examples.

After 100 parts by weight of sodium silicate, 15 parts by weight of calcium silicate, 115 parts by weight of colemanite, and 15 parts by weight of aluminum tripolyphosphate were mixed with water for 10 minutes with a ball mill, the resulting paint was spray-coated on a steel plate for enamel, The test body 1 which dried by baking with the hot air of 300 degreeC for about 50 minutes, and produced | generated the coating film about 25 micrometers thick was obtained.
Moreover, after spray-coating the coating material of a composition same as the above to the galvanized steel plate, it processed similarly to the case of the test body 1, and the test body 2 was obtained.

After 100 parts by weight of sodium silicate, 20 parts by weight of zinc phosphate, 120 parts by weight of urexite and 10 parts by weight of sodium tripolyphosphate are mixed with water for 10 minutes by a ball mill, the resulting paint is spray-coated on a steel plate for enamel, The sample 3 was dried and baked with hot air at 300 ° C. for about 50 minutes to produce a coating film having a thickness of about 25 μm.
Moreover, after spray-coating the coating material of a composition same as the above to the galvanized steel plate, it processed similarly to the case of the test body 3, and the test body 4 was obtained.

100 parts by weight of sodium silicate, 10 parts by weight of calcium silicate, 10 parts by weight of zinc phosphate, 50 parts by weight of colemanite, 50 parts by weight of urexite, 10 parts by weight of sodium tripolyphosphate, 20 parts by weight of sericite with water and 10 parts by ball mill After mixing for 5 minutes and spray-coating the resulting paint on a steel plate for enamel, it was dried and baked with hot air at 300 ° C. for about 50 minutes to obtain a specimen 5 having a coating film having a thickness of about 25 μm.
Moreover, after spray-coating the coating material of the composition on the galvanized steel sheet, the same treatment as in the case of the test body 5 was performed to obtain the test body 6.

Then, each specimen was subjected to a neutral salt spray test for 500 hours in accordance with JIS Z2371, and all the specimens were good with no rust generation.
In addition, when a combined cycle anti-corrosion resistance test was conducted according to JIS K5621, all the specimens withstood 28 cycles.

Claims (3)

  Calcium silicate or zinc phosphate is added to an alkali metal silicate, and natural glass mainly composed of colemanite or urexite and having an elution effect of diboron trioxide is used as a scale-like material with an average particle size of 30 μm or less. An inorganic coating composition, which is mixed as fine powder and further blended with tripolyphosphate.   The inorganic coating composition according to claim 1, wherein fine powdery sericite (sericite) having an average particle size of 30 µm or less is blended.   5 to 70 parts by weight of calcium silicate or zinc phosphate, 5 to 200 parts by weight of flaky fine powder of natural glass, 1 to 25 parts by weight of tripolyphosphate, 100 parts by weight of alkali metal silicate, finely powdered sericite The inorganic coating composition according to claim 2, wherein the content is 10 to 30 parts by weight.