JPH08283661A - Composition for coating layer - Google Patents

Abstract

PURPOSE: To obtain a composition which can form a coated layer which is thick, transparent and smooth and has excellent electrical insulating properties free from cracking and leveling reduction and high resistance to abrasion, weathering and corrosion. CONSTITUTION: This composition comprises (A) a copolymer prepared by hydrolytic polycondensation reaction between (a) 100 pts.wt. of an alkylalkoxy-silane of the general formula: Rn Si(OR<1> )4-n0 (R, R<1> are each a 1-8C alkyl, n is 1 or 2) and (b) 0.1-20 pts.wt. of a tetraalkoxy-silane given by the general formula: Si(OR<2> )4 (R<2> is a 1-8C alkyl) and (B) microfine silica particles with an average particle size of >=0.01μm.

Description

Detailed Description of the Invention

[0001]

The present invention relates to glass products, metal products,
The present invention relates to a coating composition applied to the surface of a plastic product, a ceramic product or the like for the purpose of imparting properties such as electric insulation, abrasion resistance, weather resistance and corrosion resistance. In the present invention, since a transparent and smooth film having a larger film thickness than before can be formed on the product surface, it can be expected to be used in a wide range of fields.

[0002]

2. Description of the Related Art Compositions in which colloidal silica is mixed with a partial condensate of an organoalkoxysilane are known to be used for the purpose of imparting the above-mentioned properties to the surface of various products (JP-A-59). -68377, JP-A-62-7
9274). Further, JP-A-1-306476 discloses a composition in which silica fine particles are mixed with a partial condensate of 100 parts by weight of alkyltrialkoxysilane and 20 to 130 parts by weight of tetraalkoxysilane. Furthermore, JP-A-2-3468 describes a composition in which titania fine particles are mixed with the above partial condensate.

[0003]

Ceramic substrates, which are widely used together with silicon substrates and glass substrates for integrated circuit modules, have a smooth surface because they are sintered bodies of high hardness inorganic compound crystals. Only a module having a low degree of circuit integration and a low degree of circuit integration can be obtained compared to a silicon substrate or a glass substrate. In order to eliminate this drawback, it is common to employ a mechanical polishing method, but it is very difficult to polish because it is unavoidable that defects of crystal grains and cracks along crystal grain boundaries occur. The SiO ₂ thin film forming method has been proposed as a solution to the drawbacks of the mechanical polishing method, but the leveling property of the composition is insufficient, and the thickness of the SiO ₂ thin film that can be formed by one-time application and firing is extremely high. Since it is thin, it is necessary to increase the number of repetitions of coating and firing in order to obtain a smooth surface.
On the other hand, in order to impart excellent electrical insulation properties to the surface of the glass substrate or the surface of the magnetic material, a high hardness film having a film thickness of several to several 10 μm is required. To obtain highly practical properties for the above purpose, a firing temperature of 400 ° C. or higher is required. However, when an insulating film is formed by a coating firing method using a composition in which silica fine particles or titania fine particles are mixed with the above-mentioned organic alkoxy partial condensate, cracking is avoided by firing at a temperature of 400 ° C. or higher. It was difficult to obtain a highly hard and smooth coating film having a hardness of 1 μm or more.

[0004]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above-mentioned object, the present inventors have found that a copolymer obtained by hydrolyzing and polycondensing an alkylalkoxysilane and a tetraalkoxysilane in a specific weight ratio and silica. The present invention has been completed by finding that a smooth coating film having a high hardness of 1 μm or more can be formed on the surface of a base material without cracks by coating and baking the composition containing fine particles.

The present invention is directed to alkylalkoxysilanes 10
A copolymer obtained by hydrolysis-polycondensation of 0 parts by weight and 20 parts by weight or less of tetraalkoxysilane, and an average particle size of 0.01 μ.
A coating composition containing silica fine particles of m or more.

In the present invention, an alkylalkoxysilane (hereinafter referred to as “AAS”) is represented by the general formula: R _n Si (OR ¹ ) _4-n ───────────── (1) And R and R ¹ in the formula are alkyl groups having 1 to 8 carbon atoms, for example, methyl group, ethyl group, propyl group,
Isopropyl group, normal butyl group, normal hexyl group, 2-ethylhexyl group and the like, and R and R ¹ are
The silane compounds may be the same or different and n is 1 or 2.

In consideration of reactivity, R is an alkyl group having 1 to 4 such as methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltributoxysilane, ethyltrimethoxysilane and ethyltriethoxy. Silane, ethyltriisolopoxysilane, ethyltributoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, isopropyltriisopropoxysilane, isopropyltributoxysilane, dimethyldimethoxysilane,
Dimethyldiethoxysilane, dimethyldiisopropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldiisopropoxysilane, diethyldibutoxysilane, diisopropyldimethoxysilane, diisopropyldiethoxysilane, diisopropyldiisopropoxysilane , Diisopropyldibutoxysilane and the like are preferably used.

On the other hand, tetraalkoxysilane (hereinafter,
It is written as "TAS". ) Is represented by the general formula: Si (OR ² ) ₄ ─────────────── (2), wherein R ^{2 in} the formula is R in the general formula (1). And a silane compound having the same alkyl group as R ¹ .
For example, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane and the like are more preferably used.

The copolymer of AAS and TAS is the above-mentioned AA
The mixture can be synthesized by hydrolyzing and polycondensing a mixture of S and TAS in a mixing ratio of 0.1 to 20 parts by weight, preferably 5 to 20 parts by weight with respect to 100 parts by weight of the former. 40 if the mixing ratio of TAS exceeds 20 parts by weight.
The film obtained by baking at 0 ° C. or higher is likely to have cracks, and a film having a high hardness of several μm or more and a smooth surface cannot be obtained. Usually, this synthetic reaction is carried out by heating in the presence of an acid catalyst such as hydrochloric acid, sulfuric acid, sulfonic acid, phosphoric acid or boric acid.

The silica fine particles may be either silica particles having an average particle diameter of 0.01 μm or more, or silica sol in which silica fine particles are dispersed in a dispersion medium. Preferably, the average particle size is 0.0
It is a silica sol of 1 to 10 μm.

The solvent of the composition is not particularly limited, but for example, alcohols such as ethanol, n-butanol and 2-ethylhexanol, esters such as ethyl acetate and butyl acetate, di-n-butyl ether and diethylene glycol. Examples thereof include ethers such as monobutyl ether.

The composition of the present invention is obtained by uniformly dispersing silica particles of 0.01 μm or more in an organic solvent solution of a copolymer of 100 parts by weight of AAS and 20 parts by weight of TAS or less. The mixing ratio of coalesce and silica can be arbitrarily selected depending on the thickness of the coating film to be formed and the coating method of the composition, but in the case of obtaining a smooth coating film with high hardness of 1 μm or more, AAS A mixing ratio of 10 to 500 parts by weight of silica fine particles is preferable with respect to 100 parts by weight of the copolymer of and TAS converted into SiO ₂ .

The method of coating the surface of the substrate is not particularly limited, and it can be applied by any means such as a dipping and lifting method (dipping method), spraying, a roll coater, and brush coating, but coating with a uniform film thickness is possible. A dipping method that can obtain a film and enables mass production is preferably adopted.

[0014]

EXAMPLES The present invention will be described in detail with reference to examples.
However, the present invention is not limited to the following examples.

Example 1 Tetraethoxysilane 18.7 g, methyltriethoxysilane 144.3 g, 0.05N hydrochloric acid aqueous solution 5.4 g
Was charged in a reaction vessel, and the mixture was stirred and held under reflux for 1 hour to obtain a copolymer solution of tetraethoxysilane and methyltriethoxysilane. To the obtained copolymer solution, a mixture of ipropyl alcohol-dispersed silica sol (average particle size of 0.05
μm) 177. 4 g was added, and the mixture was further stirred and held under reflux for 1 hour to obtain a composition (1) having a concentration of 29% by weight calculated as SiO ₂ . Then, 59.9 g of n-butanol was added, and the concentration converted to SiO ₂ was 25% by weight of SiO ₂
A film forming composition (A) was obtained.

[0016] Examples 2 to 12 The composition obtained in Example 1 in (1), n-butanol various diluents added instead of, SiO ₂ conversion concentration shown in Table 1 is 25% by weight of SiO ₂ Film forming composition (B)
(L) was obtained.

Examples 13 and 14 A method similar to Example 1 except that the amount of the silica sol mixture used in the preparation of the composition (A) was doubled and the amount of n-butanol was changed to 99.0 g. Due to SiO ₂
A film forming composition (M) was obtained. Similarly, the amount of the silica sol mixture was tripled, and the amount of n-butanol was 138.0.
A composition (N) for forming a SiO ₂ film was obtained as g.

Example 15 In the copolymer solution of tetraethoxysilane and methyltriethoxysilane obtained in Example 1, a mixture of ipropyl alcohol-dispersed silica sol having an average particle size larger than that of Example 1 (average particle size 0 (.33 μm) 182.8 g was added, and the mixture was stirred and held under reflux for 1 hour to obtain a composition having a SiO ₂ conversion concentration of 30% by weight. Then, n-butanol 75.8
g was added to obtain a SiO ₂ film-forming composition (O) having a SiO ₂ conversion concentration of 25% by weight.

Example 16 A composition having a SiO ₂ -equivalent concentration of 35% by weight was obtained by distilling off the low boiling point alcohol produced by the reaction from the composition having a SiO ₂ -equivalent concentration of 30% by weight obtained in Example 15. Got
Then, 54.0 g of n-butanol was added to obtain a SiO ₂ film-forming composition (P) having a SiO ₂ conversion concentration of 30% by weight.

Comparative Example 1 The amount of tetraethoxysilane used in the preparation of the composition (A) was 74.8 g, the amount of methyltriethoxysilane was 96.2 g, and the amount of n-butanol was 51.9.
In the same manner as in Example 1 except that the content of SiO ₂ was changed to g
A film forming composition (Q) was obtained.

Comparative Example 2 A partial condensate of tetramethoxysilane (“Atron NSi-500” manufactured by Nippon Soda Co., Ltd.) was used as a SiO ₂ film forming composition (R).

The compositions of the examples and comparative examples are summarized in Table 1.

[0023]

[Table 1]

Test Example A cleaned soda lime glass was coated with SiO 2.₂Film forming composition
After applying the material (A) by the dipping method, 500 ° C
On the glass substrate surface for 30 minutes ₂Shape the membrane
I made it. SiO obtained₂Visually check the surface of the film
Condition observation and thin film step measuring instrument (Kosaka Laboratory, ET
-10 type) to measure the film thickness. Table 2 shows the test results
Show.

[0025]

[Table 2]

[0026]

The coating composition of the present invention not only imparts electrical insulating properties, abrasion resistance, weather resistance, corrosion resistance and other properties to the surface of various substrates, but also provides a thicker film than before. It is characterized in that a transparent and smooth film can be formed. Further, by adjusting the average particle size and / or the compounding amount of the silica fine particles in the composition, a coating film having an arbitrary film thickness can be obtained, and crack generation and leveling property, which are problems when forming a thick film, are caused. Since it does not decrease, it exhibits an excellent effect in coating a substrate having a rough surface condition or a substrate required to have characteristics such as excellent electric insulation.

Claims (1)

[Claims] 1. A coating composition comprising the following (a) and (b): (A) Alkylalkoxysilane 100 represented by the general formula R _n Si (OR ¹ ) _4-n (R and R ¹ are alkyl groups having 1 to 8 carbon atoms, and n is 1 or 2).
Copolymerization by hydrolytic polycondensation of 0.1 to 20 parts by weight of tetraalkoxysilane represented by the general formula Si (OR ² ) ₄ (R ² represents an alkyl group having 1 to 8 carbon atoms). Coalescence (b) Silica fine particles having an average particle size of 0.01 μm or more