JPH0196265A - Coating agent - Google Patents

Abstract

PURPOSE:To obtain a coating agent capable of forming a coating film having excellent adhesivity, water resistance, chemical resistance, heat resistance, corrosion resistance and electrical insulating properties, comprising a silicone oligomer of ladder polymer type containing an ethoxy group and a hydroxyl group and having a specific mol.wt. and an organic solvent as main components. CONSTITUTION:The aimed coating agent comprising a silicone oligomer of ladder type which contains 1-10wt.% ethoxy group and 1-10wt.% hydroxyl group, has 300-800mol.wt. and is shown by the formula [R is alkyl, (substituted) phenyl or OH; end is ethoxy or OH with the proviso that all ends are not OH] and an organic solvent (e.g. alcohol, ketone, cellosolve or aromatic hydrocarbon) as main components.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can form a cured coating film with excellent adhesion, crack resistance, water resistance, chemical resistance, heat resistance, corrosion resistance, electrical insulation, etc. It relates to coating agents and is widely used in various fields including the mechanical industry, electrical equipment industry, and electronic industry.

[Prior Art] Ladder-type silicone oligomers usually have the following general formula (
It is a ladder-like compound represented by 1), and the molecular weight is usually 1.
．． It is from 000 to ooo.

[In the formula, R is an alkyl group, phenyl group or hydroxyl group]

This ladder-type silicone oligomer can be dissolved in many organic solvents and coated on metals, ceramics, semiconductors, plastics, etc. After coating, it is thermally cured, resulting in higher hardness and lower hardness than conventional silicone resins.
Because it can form a cured coating film with excellent heat resistance, corrosion resistance, electrical insulation, etc., it is used in fields such as the mechanical industry, electrical equipment industry, and electronic industry.

However, the cured coating film formed from the ladder-type silicone oligomer is prone to cracking, and there are restrictions on the coating thickness and curing conditions. Furthermore, adhesion, water resistance, and chemical resistance were also unsatisfactory.

In order to prevent the occurrence of cracks, attempts have been made to use a ladder-type silicone oligomer with the addition of a plasticizer or flexible plastic. However, in this method, since the plasticizer and flexible plastic added are organic compounds, it is difficult to maintain heat resistance at around 400° C. as in the case of a cured coating film made of ladder-type silicone oligomer alone.

[Problems to be Solved by the Invention] The purpose of the present invention is to maintain the above-mentioned characteristics of the cured coating film formed from the conventional ladder-type silicone oligomer, and to eliminate the drawbacks of the cured coating film formed from the ladder-type silicone oligomer. Prevents the occurrence of certain cracks, prevents water, solvent, air, etc. from entering the base material due to cracks in the cured coating, and improves the adhesion, crack resistance, water resistance, chemical resistance, and heat resistance of the cured coating. The present invention provides a coating agent that improves corrosion resistance, electrical insulation, and the like.

[Means for Solving the Problems] As a result of a detailed study on the relationship between the molecular structure of ladder-type silicone oligomers and the performance of cured coatings, the present inventors found that the molecules have specific amounts of ethoxy groups and hydroxyl groups. However, the present inventors have discovered that a cured coating film formed from a ladder-type silicone oligomer having a specific molecular weight can extremely effectively achieve the above object, and have completed the present invention.

That is, the present invention relates to a coating agent characterized in that the main components are a ladder-type silicone oligomer with a molecular weight of 300 to 800 containing 1 to 10% of ethoxy groups and 1 to 10% of hydroxyl groups, and an organic solvent. .

The ladder type silicone oligomer used in the present invention has a structure represented by the following general formula (n).

[In the formula, R is an alkyl group, a phenyl group, a substituted nyl group, or a hydroxyl group, and the terminal is an ethoxy group or a hydroxyl group. However, not all of the terminals are hydroxyl groups.

] The above general formula representing a ladder-type silicone oligomer (
In II), the alkyl group is a methyl group, a propyl group,
A lower alkyl group having 1 to 8 carbon atoms such as a butyl group and an octyl group is preferable, and a methylphenyl group is preferable as the substituted phenyl group.

The ethoxy group content in the ladder-type silicone oligomer represented by the maximum (n) above is 1 to 10% by weight,
Moreover, the hydroxyl group content is 1 to 10% by weight, including the side chain hydroxyl groups and the terminal hydroxyl groups.

If the content of ethoxy groups and hydroxyl groups in the ladder-type silicone oligomer is less than 1% by weight each, it will not crosslink even if the temperature is raised after coating the substrate, and the adhesion and
Poor water resistance, chemical resistance, corrosion resistance and heat resistance. on the other hand,
When the content of ethoxy groups and hydroxyl groups in the ladder-type silicone oligomer is each more than 10% by weight, it has disadvantages of poor adhesion, water resistance, and chemical resistance.

Further, the ladder-type silicone oligomer represented by -maximum (n) above has a molecular weight of 300 to 800. If the molecular weight of the ladder-type silicone oligomer is less than 300, if the substrate is coated and then heated and cured,
Part of the ladder-type silicone oligomer evaporates, and not only is it impossible to obtain a sufficiently cured coating film, but also the adhesion, crack resistance, water resistance, and chemical resistance are poor. On the other hand, when the molecular weight of the ladder-type silicone oligomer exceeds 800, cracks are likely to occur in the cured coating film as in the case of using a conventional ladder-type silicone oligomer, and the characteristics of the present invention are lost.

Furthermore, the above-maximum (II) used in the present invention
When using a ladder-type silicone oligomer represented by
The amount of impurities mixed in (e.g.) is 0. It is desirable that the amount is 1 ppm or less.

If a ladder-type silicone oligomer containing more than 0.1 ppIIl of metal impurities is used as a coating agent for semiconductors, the metal impurities will diffuse into the semiconductor, preventing the semiconductor from achieving its original performance and causing computer malfunctions and other problems. This is not desirable because it causes time delays.

The coating agent of the present invention is prepared by mixing the ladder-type silicone oligomer represented by -maximum (n) and an organic solvent. There are no particular restrictions on the organic solvent as long as it dissolves the ladder-type silicone oligomer; typical examples include alcohols such as methanol, ethanol, propatool, butanol, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, Esters such as amyl acetate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cellosolves such as cellosolve, cellosolve acetate, butyl cellosolve,
Examples include aromatic hydrocarbons such as benzene, toluene, and xylene. Two or more of these organic solvents may be used in combination.

The mixing ratio of the ladder-type silicone cone oligomer and the organic solvent expressed by the above-mentioned maximum (n) cannot be determined unconditionally as it varies depending on the coating method employed, but it is usually based on 100 parts by weight of the ladder-type silicone oligomer. , the organic solvent is preferably 30 to 500 parts by weight.

The coating agent of the present invention may contain pigments, fillers, dyes, ultraviolet absorbers, coupling agents, antifoaming agents, curing accelerators, and other additives, if necessary.

As described above, the coating agent of the present invention having the J8 structure is useful as a coating agent for substrates such as metals, ceramics, plastics, and semiconductors.

In order to form a cured coating film on a substrate using the coating agent of the present invention, for example, the coating agent can be applied to the substrate by dip coating, roller coating, flow coating, spray coating, etc.
After coating by means such as a spin code, the solvent is evaporated at room temperature to 120°C. Then 150
It is heated to a temperature above ℃ to make it three-dimensional and harden it. When the coating agent contains a curing accelerator such as a metal soap or an amine, curing can be carried out at room temperature or below 120°C. Moreover, if the cured coating film obtained using the coating agent of the present invention is heated to 500°C or higher, the above-mentioned -maximum (
It is also possible to create a silicon oxide film by decomposing and volatilizing the side chain R of the ladder-type silicone oligomer represented by II).

[Examples] Hereinafter, the present invention will be explained in more detail by referring to Examples and Comparative Examples.

In addition, each physical property value in Examples and Comparative Examples was measured according to the following method.

(1) Presence or absence of cracks The coated surface was visually observed using a microscope with a magnification of 100 times to determine the presence or absence of cracks.

(2) Adhesion: 100 base-shaped cuts were made at 1 mm intervals in the cured coating film, cellophane tape was applied and quickly peeled off, and the number of base lines that did not peel off was indicated.

(3) In accordance with JIS K5400, soak the water-resistant coated plate in warm water at 50°C for 2 hours.
The sample was immersed for 4 hours, then pulled out and the surface condition was observed with the naked eye.

(4) The chemical-resistant coated plate was immersed in acetone at 30°C for 24 hours, and immediately after being pulled out, the surface was rubbed with a cloth to observe elution and swelling.

Example 1 In the above-mentioned maximum (n), R is a methyl group and a phenyl group (
1 kg of a ladder-type silicone oligomer with a molar ratio of 2:1), a terminal ethoxy group content of 6% by weight, a total hydroxyl group content of terminal hydroxyl groups and side chain hydroxyl groups of 3% by weight, and a molecular weight of 480. A coating agent was prepared by dissolving it in 4 kg of toluene. 5c of this coating agent
The coating was applied by dip coating onto an aluminum flat plate measuring 5 cm x 5 cm, so that the thickness of the dry coating film was 5 μm. 30 minutes at room temperature after application
After drying for a minute, it was kept at 100°C for 30 minutes to volatilize toluene, and then heated at 200°C for 30 minutes to perform curing.

The test results for the coated surface after cooling are shown in Table 2.

Comparative Examples 1 to 6 In the above general formula (n), R consists of a methyl group and a phenyl group (molar ratio 2:1), and the molecular weight, terminal ethoxy group content, terminal hydroxyl group and side chain are as shown in Table 1. A coating agent was prepared in the same manner as in Example 1, except that a ladder-type silicone oligomer having a total hydroxyl group content of The performance of the coating film is as shown in Table 2, and was not as good as the ladder-type silicone oligomer having the composition and molecular weight of Example 1.

Red Table 1 Table 2 Example 2 In the general formula (n), R consists of a phenyl group,
And the ethoxy group content is 7% by weight, the total hydroxyl group content of terminal hydroxyl groups and side chain hydroxyl groups is 4% by weight, and the molecular weight is 4.
After dissolving 1 kg of ladder-type silicone oligomer No. 90 in 2 hg of a mixed solvent of butanol and toluene (weighted 1:2), 500 g of mica powder and 400 g of titanium white were blended to prepare a white coating agent. This coating agent was spray-painted on a steel plate specified in JIS K5400, dried at room temperature for 30 minutes, and then dried at 250°C for 30 minutes.
Cure for 0 minutes and cool to room temperature. The thickness of the cured coating is 2
It was 0 μm. The results of testing this cured coating were as follows.

Presence of cracks None Adhesion 100/100 Water resistance
No abnormalities Chemical resistance No abnormalities Furthermore, this test piece was kept at 450° C. for 40 hours, cooled, and observed. The results were the same as the above, and no abnormalities such as cracking were observed.

Example 3 The coating agent prepared in Example 1 was spray-painted on the alumina-sprayed surface of a steel plate on which alumina was sprayed, and sealing was performed. After drying at room temperature for 30 minutes, it was cured by heating at 250° C. for 20 minutes. The amount of coating agent applied was 13 g (in terms of solid content) per 1 bag. No cracks were observed on the surface of the coated product, and no water penetration into the interior was observed even after immersion in hot water at 50°C for 24 hours. On the other hand, when the alumina-sprayed steel plate without the ladder-type silicone oligomer was immersed in water, water intrusion into the interior was observed.

Example 4 In the above-mentioned maximum (II), R consists of a methyl group,
and the ethoxy group content is 5 mm%, the total hydroxyl group content of terminal hydroxyl groups and side chain hydroxyl groups is 4% by weight, and the molecular weight is 4
40 ladder-type silicone oligomers (metal-containing ff1
Na: 0.05ppIIl, K: 0.003
ppm, Fe: 0.007ppm) 1kg
was dissolved in 5 kg of cellosolve acetate to prepare a coating agent.

This coating agent was coated onto a 6-inch silicon wafer using a spin coater. The rotation speed is a per minute,
The film thickness was 0.8 μm with ooo rotation.

After coating, it was cured by heating at 200° C. for 1 hour. No cracks were observed on the surface, and the withstand voltage of the coated surface was 40 kV/dragon. This coating was heated to 700℃ for 3
No cracks were observed even after heating for 0 minutes and cooling.

On the other hand, when similarly coated using a ladder-type silicone oligomer with the same composition as above and a molecular weight of 1800, cracks were observed in the cured film after curing at 200°C for 1 hour, and cracks were observed under a microscope when cured at 200°C for 30 minutes. Upon heating, cracks were generated that were visible to the naked eye.

Example 5 In the above-mentioned maximum (II), R consists of a methyl group,
and has an ethoxy group content of 5% by weight, a total hydroxyl group content of terminal hydroxyl groups and side chain hydroxyl groups of 4% by weight, and a molecular weight of 4.
After dissolving 1 kg of ladder-type silicone oligomer No. 40 in 3 kg of a mixed solvent of ethanol and butanol (weight ratio 1:2), 0.3 g of ultraviolet absorber and formate of tetramethylammonium hydroxide No. 40 as a curing catalyst were added.
A coating agent was prepared by blending g. This coating agent was coated on a 50 cm x 50 cm, 1 mm thick polycarbonate sheet by a dipping method, dried at room temperature for 30 minutes, and then heated at 100° C. for 1 hour to cure. As a result of performing a performance test on the coated surface, no cracks were observed under a microscope, and the adhesion was 10G/100, and no abnormalities were observed in water resistance and chemical resistance tests. Note that the surface hardness was 4H in terms of pencil hardness.

[Effects of the Invention] As explained in detail above, the coating agent of the present invention does not cause cracks in the cured coating film compared to coating agents using conventional ladder-type silicone oligomers, and has excellent adhesion, water resistance, Excellent chemical resistance, corrosion resistance, heat resistance, and as an insulating coating agent.

Therefore, it is useful as a coating agent for metals such as iron, aluminum, copper, etc., a gloss finishing and sealing treatment for ceramic products, a hard coating for plastics, and an insulating coating agent for semiconductor products, particularly IC-related products.

Claims (1)

[Claims] A coating agent characterized in that the main components are a ladder-type silicone oligomer having a molecular weight of 300 to 800 and containing 1 to 10% by weight of ethoxy groups and 1 to 10% by weight of hydroxyl groups, and an organic solvent.