JPS5964671A - Formation of inorganic coating film - Google Patents

Abstract

PURPOSE:To obtain an inorg. coating film excellent in weatherability and resistance to corrosion and solvents, by using a highly condensed product free from silanol groups, derived from a mixture of two alkoxysilanes, as a film- forming component. CONSTITUTION:A mixture of about 5-95wt% tetraalkoxysilane of formula I (wherein R is a 1-8C hydrocarbon group) or its precondensates with about 95- 5wt% trialkoxysilane of formula II (wherein R' is a 1-12C hydrocarbon group) or its precondensates is hydrolyzed in the presence of an acid catalyst in a water-soluble solvent (e.g, ethanol) and adjusted to pH of 7 or above by the addn. of sodium hydroxide, etc. to be subjected to condensation, forming a high condensate free from silanol groups (a degree of condensation of about 20 or higher). A coating is prepd. from said condensate as a film-forming component, applied to a substrate, and cured by moisture to form an inorg. coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming an inorganic coating film, and more specifically to a method of forming a coating film using a coating material containing an inorganic binder containing silicon as a film-forming component.

Conventionally, many paints that use silicate as a binder have been proposed, including corrosion-resistant paints such as alkyl silicate-based zinc clinching paints and alkali silicate-based zinc clinching paints, and organosilicon-based heat-resistant paints such as polydimethylsiloxane. Paints etc. are well known.

Alkyl silicate zinc rich paint is represented by the following general formula RO-8i-0-R...001 ((l), LR represents carbon & 1-8 hydrocarbon group): 0-organic silicon A compound or (and) low condensate is used as a starting material, hydrolyzed in the presence of an acid catalyst such as hydrochloric acid, partially condensed, and used as a binder, to which a large amount of zinc dust is added.

This binder has many silanol groups on the wood end due to acid hydrolysis, and these silanol groups are metastable in the acidic region. This paint is mixed with zinc dust before painting, and this zinc dust consumes the acid catalyst and also reacts with the binder, resulting in crosslinking and curing. Although the degree of progress of the condensation reaction of the above-mentioned hydrolyzate varies depending on the amount of reaction water and reaction conditions, 11!11 fine products are not produced in an acid-catalyzed reaction (in an acidic region). Even when no zinc powder is added, the stability of this product usually decreases after 3 to 6 months, and it tends to thicken and gel. In addition, the pot life of the paint containing Ingu as a film-forming component after adding zinc powder is about 5 to 10 hours, and the curing reaction is based on the reaction between the zinc powder and the silanol groups of the binder. If a non-warping general pigment is used in place of zinc powder, a coating film with a thickness of 1 μm or more cannot be formed, and the coating performance is extremely poor, making it impractical.

However, JP-A-56-116761 discloses a one-component zinc clinch paint using a low condensed alkyl silicate and adding alkyl titanate or alkyl zirconate as an M aeration aid. In this curing reaction, a large amount of alcohol is produced as a by-product due to moisture curing, and as the alcohol evaporates, a large volume shrinkage occurs. Therefore, it is difficult to use this product for anything other than zinc clinch paint that contains a large amount of zinc dust, and it cannot be used as a clear paint or a paint for forming thick films.

Organosilicon resin such as crushed boridimedylsiloxane/
(Moisture-curable inorganic paints such as harsh clear paints and zinc-free enamels have been developed, but since the binder components of these have many alkyl groups, It has no heat resistance, the cohesive force of the paint film is small, and it is difficult to apply another paint on top of the formed paint film, so it is only used for limited purposes. Not used.

It is also known to use highly hard organosilicon resins for surface modification of plastics, but in all cases the crosslinking functional group is silanol.

The present inventor has been conducting research in order to solve the problems of paints using this type of silicon-containing compound, but in this research, the 11-organic silicon compound represented by the above general formula ) After hydrolyzing a mixture of the low condensate and the organosilicon compound represented by the following general formula [B] and/or the low condensate I in the presence of an acid catalyst, the pH thereof is adjusted to 7 or higher. The condensate obtained by condensation is a highly finely divided substance that does not have silanol groups, and when a paint containing this as a film-forming component is applied to an object, it is cured by the moisture in the air and has excellent physical properties. They found that it was possible to obtain a coating film that can be applied to strings, and also to eliminate the above-mentioned contortions of the conventional method, and thus completed the present invention for strings.

(i.e., non-explosion) Jl, an organosilicon compound represented by the following general formula [A] and/or a lower condensate thereof, and R-0-5
i-0-R (Similar R is a 10 hydrocarbon group having 1 to 8 carbon atoms) ・・・〇】The following general formula [
After hydrolyzing the mixture consisting of the organosilicon compound represented by B] and/or its low condensate in the presence of an acid catalyst, p
An inorganic coating film characterized in that a coating containing a film-forming component of a high condensate having no silanol group obtained by condensation with H of 7 or more is applied to an object to be coated, and the coating film is cured by moisture. This relates to the formation method.

Since the above-mentioned high condensate used in the method of the present invention does not have silanol at the molecular end, it has good M storage stability, and does not gel for a long period of time even if zinc dust is added. i k
Since this high-fine compound is formed by a combination of tetraalkoxysilane and trialkoxysilane, it is possible to appropriately adjust the bending density by adjusting the blending ratio, resulting in improved curability and thick coating properties. Excellent balance,
In other words, it is possible to form an excellent inorganic coating film with a high thickness of 50 to 100 μm even with clear coating, without any cracking or peeling during curing. In addition, the main skeleton of the cured coating is 15i.
Since it is a -0-5i- bond, it has excellent properties such as heat resistance, corrosion resistance, chemical resistance, and weather resistance.

R in the organosilicon compound represented by the above general formula used as a raw material in the present invention is the same or different hydrocarbon group having 1 to 8 carbon atoms, and this! The hydrocarbon groups used in the festival include alkyl groups such as methyl, ethyl, propyl, and hexyl, aryl groups such as phenyl, tolyl, and xylyl, and cycloalkyl groups such as cyclohexyl, cyclobutyl, and cyclopentyl. 'Specific compounds include, for example, tetramethoxysilane, tetraethoxysilane, tetrapropioxysilane, tetramethoxysilane, and tetraphenoxysilane.

Moreover, the low condensate means an oligomer having a polymerization/i of 10 or less.

Further, the same applies to the organic silicide represented by the general formula [B] or the above general formula. On the other hand, R has 1 carbon number bonded to silicon through a carbon-silicon cumulative bond.
~12 hydrocarbon groups, and hydrocarbon groups include alkyl groups such as methyl, ethyl, propy/L/, hexyl, and octyl, aryl groups such as phenyl, tolyl, xylyl, and naphthyl, and cyclohexyl, cyclogutyl, and cyclopentyl. Such as a cycloargyl group.

Specific compounds include methyltrimethoxysilane,
Examples include methyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane.

In the method of the present invention, 11] general formula 〇] and (B
) to obtain a sieve network mixture, it is appropriate to mix the two components in the following proportions after sintering the fibers.

Compound of general formula (9): 5 to 95% by weight, preferably 20 to 80% by weight General formula (B) compound@: 5 to 95% by weight, preferably 20 to 80% by weight In the above formulation, compound If the amount of is less than 5% by weight, i.e. CB), the compound is
If it exceeds %, the curing properties of the inorganic coating film formed using this condensate will be poor, and the two-coating properties will be poor. In addition, ■) If the amount of the compound is less than 5% by weight, that is, ■If the amount of the compound exceeds 1% of 95 monoh, it is possible to apply a 1V coating using this condensate.・There is a drawback that hl- is more likely to occur.

''; except for condensing a mixture of the general formula [A] and a +3 silicon compound represented by (Bl) and/or a low condensate thereof, the mixture of the compound and/or a low condensate is dissolved in water. It is added to a solvent such as alcohol thread solvent, cellosolve solvent, cellosolve acetate thread solvent, glyme solvent, etc., and in the presence of a mineral acid such as hydrochloric acid, sulfuric acid, or phosphoric acid, or an organic acid such as formic acid or 1-1 acid. , water is added at a ratio of 0.2 to 2 mol per mol of RO group bonded to Si, and then inorganic bases such as sodium hydroxide and potassium hydroxide, monoethylamine, diethylamine, triethylamine, etc. Add aliphatic amines, ammonia, etc. to raise the pH of the thread to 7 or higher and allow the condensation reaction to proceed.After the reaction is complete, the remaining water can be removed by distillation, azeotropy, etc. to easily increase the target product concentration. A condensate can be obtained.

The thus obtained high condensate is a tertiary circular knitted compound with a degree of condensation of at least 20 or more and a molecule of about 3,000 or more, and has sufficient performance as an inorganic binder for paints. 50-100 even with 1 clear coating
μ Hodgaku's greetings I1. A dI film can be formed. After application 1
Cures with moisture in the air at a strength of 0 minutes to 10 hours.1.
? When the cloth is brought into active contact with water, it hardens rapidly within a few minutes. At this time, the curing properties can be improved by a factor of 9 by using a strong base catalyst or a metal alkoxide such as titanium or aluminum.

In the present invention, it is possible to make a one-component rust-preventing paint by adding lead powder to a metal floor, and J+! It is also possible to make an enamel to which only 1δ' extender pigment or coloring pigment is added. In addition, if you add Tabata's pigments, you can apply thick coatings of 100μ or more without smearing or peeling.
It is Noh.

The inorganic coating 1j14 formed by the Kinori method has superior coating performance, especially corrosion resistance, compared to conventional silicate-based coatings. (11, l Solvent resistance, heat resistance, 1st grade, and excellent properties.

The present invention will be specifically explained below by way of examples.

Example 1 In a reaction vessel, 62 g of tetraethoxysilane, 125 g of methyltriethoxysilane and 187 g of ethyl alcohol were added.
was added, and the contents were heated with stirring until the temperature reached 80°C, then 30g of 062N-hydrochloric acid was added and the mixture was heated at 80°C for 10
Allowed time to react. Next, 30 g of triethylamine was added to this reaction product to raise the pH to 7 or higher and the temperature was raised to 80°C.
A feeding reaction was carried out for 2 hours, and then 100 g of benzene was added and the solvent was removed until the nonvolatile content became 40% (volume %, hereinafter the same).

The reaction product (varnish) thus obtained was transparent, had a viscosity of 5.8 centipoise, and exhibited excellent storage stability without thickening or gelling even after being stored at 30°C for 2 months. .

Next, the above varnish was applied to a polished mild steel plate to a film thickness of 5 μm, and the plate was set in a room at θ14 degrees, 20 degrees Celsius, and humidity 75% for 7 days until the temperature C8 was <1. No abnormalities such as peeling were observed in the coating film formed, and it passed the anti-slip spray test (JIS
Z2371) No spot rust was observed even after 7 days.

Example 2 In a reaction vessel, 132 g of tetragutoxysilane, 138 g of phenyltriptoxysilane, and 27 g of butyl alcohol were added.
Add 0g and stir the contents until 1r + then 100
℃, then add 66 g of 5% formic acid aqueous solution.
The reaction was carried out at 00°C for 1 hour. Next, 30 g of N-methylmorpholine was added to this reaction product to raise the pH to 7 or higher, and the binding reaction was carried out at 90'C for 2 hours. After that, 100 g of toluene was added to reduce the nonvolatile content to 40% (, % ,
(The same applies below) The solvent was removed using a sieve.

The reaction product (pheno) thus obtained was transparent, had a viscosity of 28.0 centivoids, and did not thicken or gel even after being stored at 30° C. for 2 months, exhibiting excellent storage stability.

Next, titanium oxide was dispersed in the above phenol at a rate of 100 PHR, and a paint was applied to the mild steel plate to form a film. V: 100μ and set in a room with a temperature of 20°C and an F1 degree of 75% for 7 days. The coating film thus formed showed no abnormalities such as cracks, and passed the test run for anti-slip spray (JIS Z
2371) 15 No spot rust was observed at all, and it was 7゛.

Example 3 427 g of ES-40 (tetraethoxysilane low condensate manufactured by Nippon Colcoat Co., Ltd.), 58 g of ethyltriethoxysilane, and 300 g of ethyl alcohol were added to a reaction vessel, and the contents were heated to 80°C while stirring. Thereafter, 142 g of 0.2N hydrochloric acid was added and reacted at 80°C for 30 minutes. Next, 5 g of potassium hydroxide was added to this reaction product.
was added to raise the pFI to 7 or higher, and the reaction was carried out once every 2 hours at 80°C. Then, 200 g of benzene was added for 1 hour and the solvent was removed until the non-volatile content became 30% (i.e. %). I did this.

The reaction product thus obtained (pheno) is transparent],
2 at 30℃
Even after storage for several months, there was no thickening or gelation, and it showed excellent storage stability.

Next, 116 doors and 10
0μ in a room with a temperature of 20℃ and a humidity of 75%.
I set it between u. The coating film thus formed showed no abnormalities such as flaking, and no red rust was observed even after being immersed in 40'C seawater for 3 months. Zinc powder for your pussy?
The coated coating did not gel even after being stored at 50'C for 7 days.

Comparative example 1 208 g of tetraethyl silicate was placed in a reaction vessel.

208 g of ethyl alcohol and 72 g of 0.2 N hydrochloric acid were added, and the contents were then reacted at 40° C. for 2 hours with stirring. Next, 50 g of triethylamine was added to raise the pH to 7 or more to perform a condensation reaction, and then 50 g of benzene was added and the solvent was removed until the nonvolatile content became 22%.The reaction product thus obtained was No change occurred even after storage at 30°C for 2 months, indicating excellent storage stability.

When this reaction product was applied to a polished mild steel plate to a thickness of 50 μm and placed in a room with a humidity of 20° C. and a humidity of 75% for 7 days, small cracks appeared. On the other hand, the product coated with this reaction product to a thickness of 1θμ did not show any cracking and no rusting even after 2 days of the anti-slip spray test.

Comparative Example 2 In Example 2, titanium oxide was added to the reaction product before adding all 1 FQ of N-methylmorpholine! 1l-100PHR
A 100μ film was applied and polished on a mild steel plate dispersed at a ratio of
When painted on ν, large peeling occurred after 10 minutes. Moreover, this reaction product 1-j was extracted at 50°C on the 15th day.

Comparative Example 3 In Example 3, 300 PHR of zinc powder was added to the reaction product before potassium hydroxide K was added, and it was applied to a sandblasted steel plate to a thickness of 100 μm and set in a room at 20° C. and 75% humidity for 7 days. However, no abnormalities were observed in the paint film, and no red rust was observed after being immersed in seawater at 40°C for 3 months.

However, the zinc dust-added pheno gelatinized at 20°C in 6 hours, and the zinc-dust-unadded pheno gelled at 50°C with a thickening of the 5-tube.

(that's all)

Claims (1)

[Claims] ■ An organosilicon compound represented by the following general formula (9) and/or a low condensate thereof, and R-0-5t-0-R (similar R is carbon & 1 to 8 0
Hydrocarbon group)...■] A compound obtained by hydrolyzing a mixture consisting of an organosilicon compound represented by the following general formula CB) and (or) a low condensate thereof in the presence of an acid catalyst,
An inorganic coating film characterized in that a paint containing a film-forming component of a high condensate without silanol groups obtained by condensation at a pH of 7 or more is applied to an object to be coated, and the coating film is cured by moisture. How to form.