JPS63135462A - Production of heat-resistant inorganic paint - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant inorg. paint which gives a coating film having excellent gloss, strength, water resistance, etc., by partially hydrolyzing a composite alkoxide composed of a Si alkoxide and an alkoxide of Ti, Al and/or Zr to form a sol. CONSTITUTION:A composite alkoxide composed of an Si alkoxide (A) and at least one member (B) selected from the group consisting of a Ti alkoxide, an Al alkoxide and a Zr alkoxide, is prepd. 7-25pts.wt. component B is used per 100pts.wt. component A. The composite alkoxide is partially hydrolyzed to form a sol, thus obtaining the desired heat-resistant inorg. paint. The partial hydrolysis of the composite alkoxide is carried out by reacting less than 1, pref. 0.08-0.6mol of water with 1mol of the OR group of the alkoxide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing an inorganic heat-resistant paint that can be used as a paint for various things such as ceramics, metals, and glass.

[Conventional technology]

Hitherto, high-temperature coating materials have been used as a protection measure for metal materials that come into contact with corrosive gases, liquids, and molten metals at high temperatures, but there are few that have excellent heat resistance, and only a few, such as silicon fruit tree 11m la binder, are available. The heat resistance is slightly better. However, its heat resistance is 100-200
℃ or higher, and if the temperature exceeds 200℃, the deterioration is severe and long-term usability is poor.

In addition, in order to improve heat resistance, there are methods such as applying a glaze like enamel and firing it to form an enamel coating, or spraying an inorganic oxide, but both methods require a complicated coating operation. In addition, metals such as steel and silver are generally bonded to inorganic materials such as ceramics, ceramic fibers, and glass using solder glass, and attempts have also been made to lower the temperature of soldering. However, it requires heat treatment at 400 to 500° C. or higher, and it is difficult to join large products, existing materials, or complex shapes.

In addition, considering that it will be used in an acidic gas atmosphere, it is made from acidic or neutral refractory raw materials such as silica, waxite, chamotte, mullite, and alumina, and a binder whose main component is sodium silicate. Acid-resistant fire-resistant compositions have been used. In addition, hardening agents used with sodium silicate to improve its acid resistance and water resistance include sodium silicate, aluminum phosphate, zinc oxide, organic acids,
Organic esters and the like have been used or proposed.

However, the above-mentioned fire-resistant coating materials have the disadvantage that their acid resistance is still insufficient.

In addition, the present applicant uses a binding medium consisting of a combination of a water-soluble alkali borosilicate or an equivalent mixture thereof, silicon polyphosphate, and an alkali silicofluoride in a specific proportion as an acid-resistant and water-resistant fire-resistant composition used for such purposes. As a result, a composition having excellent acid resistance and water resistance after curing was proposed (Japanese Unexamined Patent Publication No. 107960/1983).

[Problem that the invention seeks to solve]

However, although the above-mentioned binding medium maintains fluidity suitable for the construction for a relatively long time when mixed with water, there is an uneconomical problem in that the mixture with water remaining after construction hardens at room temperature and cannot be reused. was there.

In view of these circumstances, our objective is to provide a method for producing an inorganic heat-resistant paint that exhibits durability against strong acid aqueous solutions, does not change over time as a paint, and has excellent film-forming properties as a heat-resistant paint. do.

[Means for solving problems]

The present inventors conducted various tests and research on the manufacturing method of inorganic heat-resistant paints, and found that by using a composite alkoxide partially hydrolyzed sol, the coating after application and curing has excellent acid resistance and water resistance, and has adhesive properties that can withstand heating and cooling. In addition, it was discovered that this inorganic heat-resistant paint has good film-forming properties, and the present invention was achieved.

That is, the present invention uses Si alkoxide and Ti alkoxide.
This is a method for producing an inorganic heat-resistant paint, which is characterized in that a composite alkoxide consisting of at least one selected from Zr alkoxide, Zr alkoxide, and Zr alkoxide is partially hydrolyzed into a sol. Here, the partially hydrolyzed sol of a complex alkoxide is a sol that has been hydrolyzed with water at a molar ratio of less than 1 to the OR group of a metal alkoxide, and the unhydrolyzed OR group remains, and its residual rate is is 30 to 95 molar, preferably 40 to 92 molar.

Composite alkoxide partially hydrolyzed sol has an OR group residual rate of 10
When the molar ratio exceeds 0 to 95, the coating film becomes resin-like and cracks occur when dried. Alternatively, fine particles of metal hydroxides and oxides are generated in the coating film due to evaporation, resulting in a thin film and poor yield. If the residual OR group ratio of the composite alkoxide partially hydrolyzed sol is less than 0 to 30 molar ratios, the film-forming properties during coating will be poor, the workability will be poor, and the coating will crack during curing.

Partially hydrolyzed sol is a polymer that does not completely hydrolyze and polymerize molecules within a solution to form a network structure, but instead contains polymers that are partially polymerized with OR groups remaining. sol solution.

In the composite alkoxide partially hydrolyzed sol, Si alkoxide, Ti, A1. By combining Zr with one or more metal alkoxides, it suppresses cracking during hardening of the film, improves the strength of the film, and improves boiling resistance (water resistance) and chemical resistance (acid resistance, alkali resistance). A heat-resistant coating is obtained.

The composite ratio of Si alkoxide and other metal alkoxide to obtain such excellent effects is St alkoxide 1
00 parts by weight, Ti, A7. The ratio of Zr metal alkoxide is preferably 7 to 25 parts by weight, and if it is less than 7 parts by weight, cracks are likely to occur during hardening of the coating. On the other hand, if the amount exceeds 25 parts by weight, cracks are likely to occur when the coating is cured, and there is no particular advantage, and it is also economically disadvantageous. A more preferred composite ratio is 7 to 17 parts by weight.

Methods for obtaining composite alkoxy and cytopartially hydrolyzed sols include hydrolysis at room temperature, hydrolysis under reflux, and hydrolysis with the addition of a catalyst. For example, ethyl alcohol, which is a compatible solvent with water, is added to the Si alkoxide solution.
Add alcohol such as impropatul or methyl alcohol. Furthermore, acidic water containing hydrochloric acid, acetic acid, etc. was added to the solution in an amount (mol number) less than the total number of moles of alkoxy groups in Si alkoxide, and further Al1Ti, Zr
When a specific amount of one or more metal alkoxides is added and stirred, a transparent composite alkoxide partially hydrolyzed sol is obtained.

The inorganic heat-resistant paint of the present invention has a low viscosity of about 1 to 10 cp and has good workability, but if necessary, thickeners such as RPC (hydroxyglobil cellulose), RPC (hydroxyglobil cellulose), dynamic paraffin, ethylene glycol resin, and magenta can be used. The viscosity can also be adjusted by adding alcohol as a thinner and diluent.

As with organic paints, it can be applied by brush or spray. Although the coating is colorless and transparent, it can also be colored by adding an inorganic or organic coloring agent.

The adhesion process of the inorganic heat-resistant paint of the present invention involves physical adhesion due to the roughness of the material surface and OH groups on the material surface, such as Fe on the iron surface.
......OH, Si on the glass surface...OH
A strong adhesive strength can be obtained through chemical adhesion caused by the reaction between the adhesive and the OH group or OR group in the composite alkoxide partially hydrolyzed sol. In particular, the coating has adhesive properties that do not peel off even when heated to high temperatures of 800° C. or higher and to room temperature.

〔Example〕

The present invention will be specifically explained below using Examples according to the present invention and Comparative Examples.

As shown in Table 1, methyl alcohol and water were added to Si alkoxide and metal (M) alkoxide, and the mixture was stirred at room temperature to obtain a transparent composite alkoxide partially hydrolyzed sol.

Table 1 shows the characteristics of silicone resin and water glass as comparative examples.

1st Umbrella 1 Coated on a glass plate or iron plate, 100-b scratch strength, etc. 2 After coating on a stainless steel plate, whether or not water penetrates after holding at a specified temperature for 10 minutes $3 Coated on a stainless steel plate and heated Temperature book 4 that does not cause peeling when cooled with water Methyltrimethoxysilane semi-determined standard ◎...Almost no or only a small amount of elution into the acid or alkaline solution is good.○...Elution amount of about 5 to 10 cycles is good. ×... Elution amount exceeds 20 parts and is defective [Effects of the invention] When the inorganic heat-resistant paint of the present invention is applied to the surface of plywood, plastic, metal, ceramics, etc. as a top coat, the coating film exhibits the following effects. .

1) Excellent gloss and improved appearance.

2) Prevents scratches due to the high strength of the coating.

3) Good film forming properties, water repellency up to about 600°C, and improved water resistance and chemical resistance.

4) @Outer enclosure (metal oxidation resistance) is improved.

Further, even if the inorganic heat-resistant paint of the present invention is left unused, it can be reused by storing it in a sealed container, and will not go to waste.

Claims (2)

[Claims] (1) A method for producing an inorganic heat-resistant paint, which comprises partially hydrolyzing a composite alkoxide consisting of a Si alkoxide and at least one selected from Ti alkoxide, Al alkoxide, and Zr alkoxide into a sol. (2) The production method according to claim (1), wherein the partial hydrolysis is performed by reacting with water at a molar ratio of less than 1, preferably 0.08 to 0.6, relative to the OR group of the composite alkoxide.