JPH0796667B2 - Heat resistant coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Description of the Prior Art and Problems Conventionally, for rust prevention of metal products, organic resin-based paints such as epoxy resins and acrylic resins, alkali silicate-based paints, alkyl silicate-based paints, silicone resin-based paints Is widely used.

Organic resin paints such as epoxy resin and acrylic resin are
It excels in handling workability, but it cannot be used at high temperatures because the resin deteriorates significantly under conditions above 200 ° C.

Alkaline silicate-based paints are water-soluble paints, so it is necessary to completely degrease the material, and in order to improve the water resistance of the coating film, a hardening agent such as AlPO ₄ , Al ₂ O ₃ or SiO ₂ is used. Must be used and must be painted promptly after the curing agent is mixed.

An alkyl silicate-based paint is a paint binder that is obtained by hydrolyzing an alkyl silicate in the presence of an acid catalyst such as hydrochloric acid.Since it has many silanol groups at the end due to acid hydrolysis, it has an acidic region. Although it is metastable, the stability is usually lowered after 3 to 6 months, and the pot life after mixing with a basic pigment such as zinc dust is only about 5 to 10 hours.

The silicone resin-based paint uses a silicone resin alone or a modified silicone resin mixed with an organic resin such as an epoxy resin and an acrylic resin as a binder, and is generally expensive and requires a high temperature of about 200 ° C. for curing.

The present invention, as a result of various studies in view of the drawbacks of the prior art, is inexpensive by using a composite agent having a specific composition, has storage stability, is room temperature curable, is soluble in an organic solvent,
The present invention provides a coating material having excellent adhesiveness and heat resistance.

Solution The above-mentioned problems can be solved by blending a specific organoaluminum compound and / or organozirconium compound, or those with an organotitanium compound, in a coating material containing an alkyl silicate as a film-forming component. That is, the present invention provides (a) a C _1-8 alkyl silicate or a low condensate thereof, and (b) (i) a C _1-8 alkylaluminum or a chelate compound thereof and / or (ii) a C _1-8 alkylzirconate. Or a chelate compound thereof, or (iii) a mixture of a C _1-8 alkyl titanate or a chelate compound thereof and one or both of the above (i) and (ii), the component (a) and the component (b) The metal content is converted to oxides, and the weight ratio of SiO ₂ / (SiO ₂ + Al ₂ O ₃ + ZrO ₂ + TiO ₂ ) is 50 to 98%.
A heat-resistant coating composition comprising a mixture of the component (a) and the component (b) as a film-forming component.

The coating composition of the present invention can be cured at room temperature, is excellent in storage stability, adhesiveness of coating film, and heat resistance, is soluble in an organic solvent, and is less expensive than a heat-resistant coating composition using a silicone resin.

Detailed Description As the C _1-8 alkyl silicate of component (a) and its low condensate, orthomethyl silicate, methyl silicate 50, orthoethyl silicate, ethyl silicate 40,
Examples thereof include ortho n-propyl silicate, ortho n-butyl silicate, orthoisoamyl silicate and the like.

_Examples of the C _1-8 alkylaluminum component (b) and its chelate include aluminum isopropylate, mono-sec-butoxyaluminum diisopropylate,
Examples thereof include ethyl acetoacetate aluminum diisopropylate, and examples of C _1-8 alkylzirconate and its chelate include tetraisopropoxyzirconium and tetra-n-butoxyzirconium.
Examples of the C _1-8 alkyl titanate and its chelate compound include tetraisopropoxy titanium, tetra n-butoxy titanium, diisopropoxy-bis (acetylacetonate) titanium and the like.

The component (a) and the component (b) are blended in a ratio that satisfies the curing rate and storage stability. That is, the alkyl silicate is low in reactivity by itself, and the respective compounds of the component (b) are high in reactivity which are easily hydrolyzed and condensed.

The mixing ratio of component (a) and component (b) is such that the metal content is converted to oxide and the weight ratio of SiO ₂ / (SiO ₂ + Al ₂ O ₃ + ZrO ₂ + TiO ₂ ) is 50 to 98%. Must be a good ratio. If this weight ratio exceeds 98%, the curability will be poor, and if it is less than 50%, the curing reaction will be too fast and cracking will occur easily, and in terms of storage stability, handling will be difficult.

The mixture of the component (a) and the component (b) thus obtained can be used as a paint that provides a heat resistant film by mixing metal powder, metal oxide and the like.

The mixture of the components (a) and (b) thus obtained is selected from organic resins such as epoxy resin, phenol resin, polyester resin, acrylic resin, melamine resin, urea resin, alkyd resin and silicone resin. At least one resin can be blended. The blending amount of the organic resin includes components (a) and (b)
And in the solid content of the entire film-forming component consisting of an organic resin,
A mixture of components (a) and (b) should be present in an amount of 30% by weight or more. While this improves the film-forming property and adhesiveness of the paint, it can also impart heat resistance to the organic resin, so it is also possible to obtain a transparent film with excellent adhesiveness by appropriately examining the compounding ratio. Next to
Also, by mixing metal powder, metal oxide, etc., a heat resistant film with improved adhesiveness is provided.

Examples of the present invention will be shown below. The mixing ratio of each component is parts by weight.

Example 1 A composition having the following mixing ratio was applied to a steel sheet, and the temperature was 50 ° C. and the humidity was 95%.
The sample was allowed to stand for 24 hours and the dryness to the touch was examined after 24 hours. (The compounding amount in the table is converted to SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ ) Example 2 A composition prepared by dispersing a composition having the following mixing ratio by a central mill was applied onto a steel plate, and this was used as a test piece to examine the adhesion after each heating condition.

Example 3 A composition having the following mixing ratio was applied on a steel plate and heated at 180 ° C. for 20 minutes to check the film forming property.

Example 4 The composition having the following mixing ratios dispersed in a central mill was applied onto a steel plate, and this was used as a test piece to examine the adhesion after each heating condition.

Claims (3)

[Claims] 1. (a) C _1-8 alkyl silicate or a low condensate thereof, and (b) (i) C _1-8 alkylaluminum or its chelate compound and / or (ii) C _1-8 alkylzirconate. Or a chelate compound thereof, or (iii) a mixture of a C _1-8 alkyl titanate or a chelate compound thereof and one or both of the above (i) and (ii), the component (a) and the component (b) The metal content is converted to oxides, and the weight ratio of SiO ₂ / (SiO ₂ + Al ₂ O ₃ + ZrO ₂ + TiO ₂ ) is 50 to 98%.
A heat-resistant coating composition containing a mixture of the component (a) and the component (b) as a film-forming component. 2. A mixture of component (a) and component (b) and at least one selected from epoxy resin, phenol resin, polyester resin, acrylic resin, melamine resin, urea resin, alkyd resin and silicone resin. The heat resistance according to claim 1, which contains an organic resin, and the sum of the proportions of the mixture of the component (a) and the component (b) is 30% by weight or more of the solid content of the entire film-forming components including the organic resin. Coating composition. 3. The heat resistant coating composition according to claim 1 or 2, further containing a metal powder, a metal oxide and an organic solvent.