JPS6257470A - Coating composition for forming corrosion-proof electrical insulation film having excellent heat resistance and durability - Google Patents

Abstract

PURPOSE:To obtain the titled composition capable of forming a corrosion- protecting and electrically insulating film having excellent heat-resistance and durability and useful over a wide field as a corrosion-protecting film, by compounding a specific silicon compound, an alcohol, water, etc., at specific ratios. CONSTITUTION:The objective composition is composed of (A)10-40pts.(wt.) of a silicon compound of formula RSi(OR')3 (R is hydrocarbon group; R' is alkyl), (B) 10-80pts. of an alcohol, (C) 10-80pts. of water, (D) 0.01-3pts. of one or more compounds selected from acetic acid, nitric acid, hydrochloric acid, formic acid, propionic acid and maleic acid and (E) 5-60 pts. or SiO2 (silica), TiO2, Al2O3 (alumina), Cr2O3, ZrO2, Al2O3.SiO2, 3Al2O3.2SiO2, ZrO2.SiO2 (zircon) or Si3N4 or their mixture having an average particle diameter of 0.1-5mu.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention provides an anti-corrosion film with excellent heat resistance and an electrical insulation film on the surface of iron, stainless steel, aluminum and other metals, cement, glass, plastic and other base materials. The present invention relates to a coating composition capable of forming a film.

(Technical background of the invention and its problems) Recently, coating agents that can be applied to various substrates and exhibit excellent properties under various conditions have been developed.
There is a demand for a thin film with a thickness of 1100p or less that is pinhole-free and has excellent heat resistance, durability, weather resistance, moisture resistance, corrosion resistance, hardness, etc. For example, for items such as heat exchangers that are susceptible to acid corrosion, thermal conductivity is required in addition to heat resistance and corrosion resistance, and hybrid XC boards and laminated boards require insulation with good heat dissipation properties. Since a film is required, if the film formed as a result of coating is a thin film, not only will there be no risk of deterioration in thermal conductivity or mechanical strength, but it will also be extremely advantageous in terms of cost.

However, no coating agent with sufficiently satisfactory properties has been developed so far. For example, coating agents such as epoxy resin/rubber, fluorine resin/rubber, silicone resin, or ceramic vapor deposition method (CVD) are used.
method), glass lining method (PVD method) that involves sintering at high temperatures
There are coating methods such as 100. ■
The following thin films are pinhole-free and can be used for corrosion protection and electrical insulation, but each has advantages and disadvantages. That is, epoxy-based materials are inferior in heat resistance, durability, and hardness, fluorine-based materials are inferior in heat resistance, hardness, and workability, and silicone-based materials are inferior in rM heat resistance. Further, the vapor deposition method is extremely expensive, and the glass lining method requires firing at a high temperature, which limits the range of materials that can be used as the base material and increases costs.

(Object of the Invention) The present invention has been made in view of the above, and the first object of the present invention is to easily dry a thin film coated on the surface of a base material in a short time and by heating at room temperature or low temperature. It is possible,
Moreover, 1000
The object of the present invention is to provide a coating composition that forms a pinhole-free film with a film thickness of 1100 IL or less that can pass the Porto discharge test.

The second object of the present invention is to form a film having heat resistance, moisture resistance, electrical insulation, etc. on the surface of metals such as aluminum, copper, iron, glass, plastic, paper, wood, and all other base materials. The object of the present invention is to provide a coating composition that can be used for coating. In particular, the present invention relates to a coating composition that can form an electrically insulating thin film with good thermal conductivity suitable for various electronic components.

The third object of the present invention is to provide a coating composition that has a wide range of uses as a corrosion-resistant film because it has excellent heat resistance, weather resistance, and strong corrosion resistance against water, seawater, organic chemicals, and most types of acids. It's about providing things.

(Summary of the invention) To achieve the above object, the present invention has been made.

(a) 10 to 40 parts by weight of a silicon compound represented by the general formula RS i (OR゛)7 (wherein R is a hydrocarbon group and R is an alkyl group), (b) 10 to 80 parts by weight of alcohol, (C) 10 to 80 parts by weight of water; (d) 0.01 to 3 parts by weight of one of acetic acid, nitric acid, hydrochloric acid, formic acid, propionic acid and maleic acid; f; bacho r
′! Futomi=7 in Epa, “aluminum dioxide (alumina A
tyuO,,), chromium oxide (Cr2O3), zirconium oxide (ZrOj silimite (A1.Ot”S
I Oa ), synthetic mullite (3Al, 0. +
Zircon Zr
O2・SiO), silicon nitride (Si, N,...)
It is made by mixing 5 to 60 parts by weight of one or two or more of the following.

(Structure of the Invention) The coating composition of the present invention, which forms a corrosion-resistant and electrically insulating film with excellent heat resistance and durability, will be described below.

As described above, the coating composition of the present invention has (a) the general formula RSi(OR'), (wherein R is a hydrocarbon group,
10 to 40 parts by weight of a silicon compound represented by (R' is an alkyl group), (b) 10 to 80 parts by weight of alcohol, (C) 10 to 80 parts by weight of water, (d) acetic acid, nitric acid, hydrochloric acid. , formic acid, propionic acid, maleic acid in 0.01 to 3 parts, (e) silicon dioxide (SiO), titanium oxide (TiO), aluminum oxide (alumina) with a particle size of 5 microns or less; A1 YuO]), chromium oxide (Crror),
Zirconium oxide (Zro:, ), sillimite
(A lx 07 ・S iO2), synthetic mullite (
3A1.0.3 ・2Si0, ), zirconia silicate (zircon ZrO; ・5top), silicon nitride (Si
5 to 50% of one or a mixture of two or more of lN・l)
60 parts by weight, each having a mixed composition.

General formula R51 (OR') representing the silicon compound of (a) above
), R is a hydrocarbon group, such as an alkyl group such as methyl, ethyl, or butyl, or an unsaturated hydrocarbon group such as vinylallyl, and R′ is an alkyl group such as methyl, ethyl, or butyl. Among these, the most suitable is methyltrimethoxysilane. This silicon compound functions as a binder, and undergoes hydrolysis in the presence of water to change from a sol to a gel, which hardens at room temperature or by heating. That is, when the amount of the silicon compound added is small, the hardness is low and the adhesion is weak, and when the amount added is large, both the hardness and the adhesion are increased. On the other hand, since this silicon compound hydrolyzes and gels, when the amount added is small, the storage stability of the coachin composition is improved, and when it is added in a large amount, it is decreased. 10
The addition amount of ~40 parts by weight was determined based on a combination experiment with each of the components (b) to (e), of which a range of 20 to 30 parts by weight is optimal.

As the alcohol (b), lower aliphatic alcohols are suitable, and isopropyl alcohol is particularly suitable. This alcohol functions as a dispersion medium for the fine particles constituting the above (e), and the acid in (e) and (e) prevent the silicon compound in (a) from gelling due to hydrolysis.
) is intended to prevent this by a synergistic effect with fine particles.

As the water in (c) above, tap water or distilled water is used,
Tap water is usually sufficient, but distilled water is used when a highly pure coating composition is required. This water (
It is for hydrolyzing the silicon compound of a),
The amount added is determined by the relative relationship with the amount of fine particles added in (e), but it is preferable to adjust the amounts of the two to avoid a large difference as much as possible.

Acetic acid, nitric acid, hydrochloric acid, formic acid, propionic acid of the above (d),
Maleic acid is used to prevent gelation of the composition of the present invention after preparation and to accelerate curing after application, and among these acids, acetic acid is most suitable. If any of these acids exceeds 3 parts by weight, it will promote gelation of the composition after preparation and reduce storage stability. Therefore, the optimum amount to be added is 0.03 to 0.3 parts by weight.

The reason why each particulate element in (e) above is made into fine particles of 5 lm or less is because if the particle size exceeds 51L11, it becomes difficult to form a thin film without pinholes, and the dispersibility decreases. Because it does. Therefore, the optimum particle size is in the range of 0.1 to Ig,m. Particle size is 0.01~
Ultrafine particles of 0.05 ILm increase the viscosity, so their use is limited to machines with 8 to 15 layers, but they can improve transparency. In particular, if ultrafine silicon particles with a particle size of 0.01 to 0.03 ILm are used, highly transparent particles can be obtained, but storage stability deteriorates and gelation occurs in a few days.

Elements (e), such as silicon dioxide, titanium oxide, aluminum oxide, chromium oxide, zirconium oxide, zirnia silicate, sillimite, synthetic mullite, and silicon nitride, have excellent corrosion resistance. These are required to have high purity depending on their use. For example, when used for electrical insulation, it is necessary to prevent the contamination of alkali metals. This is because when a voltage is applied to a composition containing alkali ions, the alkali ions move and become conductive, and the composition cannot return to its insulating state even after the voltage application is stopped. If the voltage continues to be applied further, dielectric breakdown occurs. When the amount of these fine particles is less than 15 parts by weight, it promotes gelation and reduces storage stability, and when it is within the range of 50 to 60 parts by weight, the hardness of the coating film and the adhesion to the substrate are reduced.

Therefore, a range of 20 to 45 parts by weight is optimal.

Furthermore, since each of the fine particles (e) including silicon dioxide has its own unique characteristics, it can be used for purposes other than the above-mentioned corrosion prevention and insulation. For example, zirconia silicate can be used alone or by adding other fine particles to improve its emissivity in the far infrared region to around 0.9 or more, so it can be used as a highly efficient far infrared emitting film. . Silicon carbide can also improve thermal conductivity. Therefore, if a film with good heat insulation properties is to be obtained, it is sufficient to add something other than silicon carbide. Furthermore, yellow titanium oxide and chromium oxide (green)
can be used to form a colored film.

Adding 0.5 to 10 parts of commercially available alumina sol to a coating composition comprising each of the above elements (a) to (e) prevents gelation of the composition and simultaneously improves dispersibility. I can do it. Furthermore, nonionic or cationic surfactants, silane coupling agents, or titanium coupling agents also contribute to improving dispersibility.

(Effect of the invention) The coating composition having the above structure is coated on the surface of the base material with a coating method such as brushing, spraying, or dipping to a thickness of 7 to 50 go+ in one coat, and 20 to 10 in thickness in two coats.
It is possible to form a film of 0-1, which is 80-300
By heating and drying at ℃ for 10 to 120 minutes, a so-called pinhole-less film can be formed. When coating an outdoor structure or when heating and drying is not possible due to the nature of the base material itself, 48 to 14
It can be cured by drying at room temperature for 8 hours (7 days). In this case, as long as 6 hours or more have passed, there will be no problem with the drying effect even if it gets wet with rain or the like.

The film made of the coating composition of the present invention has heat resistance,
It has excellent weather resistance and strong corrosion resistance against water, seawater, organic chemicals, and most acids, so it can be used to protect outdoor structures from natural environments, marine structures from seawater, and even heat exchangers and exhaust gas flues. It can be used as a wide range of anti-corrosion films, including acid dew point corrosion protection, hot water tanks and chemical reaction tanks.

In addition, it is possible to form a heat-resistant, pinhole-free film with a film thickness of 100 gm or less, making it heat-resistant and moisture-proof on the surface of metals such as aluminum, copper, and iron, glass, plastic, paper, wood, and all other substrates. It is possible to form a film with excellent properties such as properties and electrical insulation properties. Since the film formed according to the present invention is a thin film, the poor thermal conductivity that is characteristic of ceramics in general does not pose any problem. Therefore, it is possible to form an electrically insulating thin film with good thermal conductivity, which is most ideal as a coating agent for various electronic components. In particular, if silicon carbide, which is the component (e) of the present invention, is used, the thermal conductivity can be further improved. The features of the present invention are summarized as follows.

(1) Since a pinhole-free state can be achieved with a thin film of 20 inches and 1100 IL, a highly airtight and hard coating can be obtained.

(2) It is heat resistant and weather resistant, and has excellent properties such as water resistance, seawater resistance, organic solvent resistance, and acid resistance, so it has a wide range of uses as an anticorrosion film.

(3) Since it is possible to obtain a highly pure coating agent that does not contain alkali metals or other impurities, it has a wide range of applications as an electrical insulating film.

(4) Metals, glass, ceramics, Shichimen I
- Can be used for almost all materials such as fibers, paper, and plastics (excluding those without functional groups such as Teflon, polyethylene, and polypropylene).

(5) It has excellent handling properties and can improve workability. That is, simple degreasing is sufficient for base treatment, and the coating can be applied at room temperature and cured by heating at 80 to 300°C for 110 to 120 minutes. If heat drying is not possible due to the material of the base material or location conditions, curing can be achieved by drying at room temperature for 2 to 7 days.

(6) Even though it is a hydrolyzable composition containing water, it can maintain stability for a long period of time without gelling, so it can ensure a shelf life of 3 months or more.

(7) When zirconia silicate is used as the component (e), the emissivity in the far infrared region can be increased.

(8) Not only a transparent film but also a colored film can be formed.

Next, the present invention will be explained by examples.

Example (1) Acid dew point (for example, in order to investigate the performance as an anticorrosion film against the phenomenon in which the combustion gas of heavy oil containing sulfur reacts with water produced by condensation and becomes sulfuric acid, which corrodes metals) Three types of composition examples A-B-C were made.

Table 1 (!I'U Minabe) group
Compound ABC (a) Methyltrimeth 20 25 30 Xysilane (b) Isopropyl 19 18 1? Alcohol (c) water (kiyari water) 3o 1G
20(d) Acetic acid
0.08 0.04 0゜05(e) Silicon dioxide
2515 (particle size 1 to L5 m) Titanium oxide (/10.'; -1 m) Chromium pentoxide (/
11~3JLm) 25 Silicon nitride (tt O, S~i p, m)
32(f) Alumina sol (Al content 20%) 3
Nonionic surfactant 1 0.5 1 Silane coupling agent 0.02 Total 100.1 100.54100. Next, a steel plate of 1100X50XlO/m size (545
Prepare 6 sheets of C), cut off all the corners, and
Eliminates sharp edges and creates a rounded taste. Using these, a Tes I piece was created by the method shown in Specification 1.

Specifications l Painting method The entire surface of the test piece was painted using air spray according to the table in 1-.

1st coat approx. 30gm (dry film thickness) and apply 2 coats at room temperature.
It was dried for 4 hours.

Approximately 40 gm was applied for the second time and dried at room temperature for 24 hours.

3rd time: same 40 lm coating and drying for 24 hours.

4th time: Approximately 40JLm was applied, and after drying at room temperature for 1 hour,
The mixture was heated at 130°C for 30 minutes and then at 130°C for 30 minutes.

When each of these steel plates was subjected to electric discharge at 2000 ports using a discharge type pinhole tester (commercially available) and the presence or absence of pinholes was examined, pinholes were observed in B-1 and A-B. The above painting method was repeated for the first and fourth times.

After that, the test was conducted again and it was confirmed that there were no pinholes.

Various tests were conducted using the test piece prepared according to Specification 1, and the test results are shown in Table 2.

Table 2 Test Items Test Conditions Hardness Pencil hardness (JIS method) Adhesion ■ Sellotape peel test ■ Tensile strength (JIS method) Heat resistance It was held at 500° C. for 240 hours in an electric furnace and allowed to cool naturally.

Cooling: 500°C and room temperature (forced cylinder cycle cooling using air blowing) was repeated 20 times.

Salt water resistance: 480 hours of frost in 4% salt water.

Boiled for 120 hours in boiling resistant aqueous tap water.

Acid resistance: Immersed in 10% sulfuric acid solution for 60 days.

■8 o'clock during 608 immersion in 10% sulfuric acid solution The mixture was heated to 70°C for 10 times.

(2) Soaked in 35% sulfuric acid solution for 60 days.

■Immersed in 60% sulfuric acid solution for 60 days.

It was immersed in 0.010% hydrochloric acid solution for 60 days.

(2) Soaked in 30% hydrochloric acid solution for 60 days.

Example (2) In order to investigate the performance as an electrical insulating film, as shown in Table 3,
E, F three types of composition examples were made, 50×50×1
Three m/m size aluminum plates and three copper plates were prepared and a test piece was created using the method of Specification 2.

Table 3 (Parts by weight) Compositions
DEF (a) Methyltrimeth 20 27 25
Xysilane (b) Isopropyl 25 20 25
Alcohol (c) Water (tap water) 32 20 2
5(d) Acetic acid 0.050.040
．． 02(e) Aluminum oxide (particle size 0.3-0.6) Silicic acid (tt1-3) bm) 25 Zirconia silicon dioxide (//t ~1.51Lm) 5 Silicon carbide (/10.3~ 0.6μm) 25(
b) Alumina sol 32 Thiionic surfactant 1 0.3 Nonionic surfactant 0.3 Total 100
．． 05 100.04 100.8 Ground treatment method
Degreasing was performed using a commercially available alkaline degreaser (aqueous solution PHII).

Painting method One side of the test piece was painted using air spray according to the table above.

Approximately 20 μm (dry film thickness) was applied and immediately heated at 120° C. for 20 minutes.

2nd time Apply about 20 luros and immediately heat at 120℃ for 2
Heated for 0 minutes.

Third time: Approximately 201 Lm was applied and immediately heated at 120° C. for 30 minutes.

The test pieces prepared according to Specification 2 were tested for electrical insulation properties, and the results are shown in Table 4.

Table 4 Example (3) Table 5 shows composition example G for producing a transparent, glossy, hard film.

Table 5 Compositions G (parts by weight) (a) Methyltrimeth 25 Xysilane (b) Isopropyl alcohol 28 Alcohol (c) Water (tap water) 40 (d) Hydrochloric acid 0.03 (e) Silicon dioxide 7 (particle size 0. 01-0.03
gm ) (f) Sodium oxide 0.01 total
100. 04 In order to investigate the performance of this composition example G, a transparent acrylic plate of 75 x 75 x 3 m/m, a steel plate (345C) of 50 x 50 x 1 m/m,
Further, three types of test pieces A-2 prepared according to Specification 1 using the composition examples shown in Table 1 were coated by the method according to Specification 3 shown below.

Specification 3 It was applied once each to acrylic plate and steel plate specification A-2 by spraying.

Heating method ℃/min 80/90 200/30 2
50/30 film thickness 3
The performance of the test piece completed according to 4.2 specifications is shown in Table 6.

Table 6 Example (4) Two types of composition examples of HφI shown in Table 7 were prepared in order to investigate corrosion prevention and cosmetic properties of steel outdoor structures due to the natural environment.

Table 7 (parts by weight) Composition HI
(a) Methyltrimeth 25 30 Xysilane (b) Isopropyl 18 25 Alcohol (C) Wood (tap water) 16 22 (d
) Acetic acid 0.2 0.2 (e) Titanium oxide yellow 52.5 (particle size 1-1.5 lm) Zirconia silicate 35 17.5 (particle size 1-3 #Ll) (f) Alumina sol nonionic interface Active agent 0.5 thionic surfactant 1000 total
100.7 100.7 then 1100X50X1
Six 0/+ size steel plates (845C) were prepared and all corners were ground to eliminate sharp edges and create a rounded appearance.

Using these, a test piece was created using the method shown in Specification 4 below.

Specifications 4 Surface treatment: Degreased using a commercially available alkaline degreaser.

Painting method: The entire surface of the test piece was painted with air spray.

1st Approximately 30 lumen (dry film thickness) of Composition Example H in Table 7 was applied and left outdoors for 24 hours.

2nd time Approximately 40 gm of H was applied in the same manner and left outdoors for 24 hours.

3rd time: Approximately 20 lm of Composition Example I in Table 7 was applied.
It was left outside at 0:00. During this time, after about 18 hours had passed, I got wet in the rain for about 4 hours and 3 other times for about 18 hours.

Various tests were conducted using five test pieces prepared according to Specification 4 (one piece was left for comparison of hue), and the test results are shown in Table 8.

Table 8 Test items Test conditions Test results Hardness Pencil hardness (JIS method) 5H adhesion ■ Cellotape peeling test No peeling ■ Tensile strength (JIS method)
Law) 60kg/cm” Water resistance Tap water 6
0 days ゛ No abnormalities Salt water resistance 4% saline 60
Days //〃 45 Salt water spraying 960 hours /l Sake resistance Weathering test (JIS method) Tooo hours 〃Heat resistance 500℃ held for 120 hours /
1. Water resistance to heat resistance as shown in h. No change in color after test. Visually check the hue after testing. The heat resistant and durable anti-corrosion film of the present invention, the coating that makes the electrical insulating film and other functional films. It can be said that the composition has excellent properties and is very effective for industrial use.

Hand Threading Neyama IL Se7 June 1985/Sun

Claims (1)

[Scope of Claims] (a) 10 to 40 parts by weight of a silicon compound represented by the general formula RSi(OR')_3 (where R is a hydrocarbon group and R' is an alkyl group); (b) alcohol 10 ~80 parts by weight, (c) 10 to 80 parts by weight of water, (d) 0.01 to 3 parts by weight of one of acetic acid, nitric acid, hydrochloric acid, formic acid, propionic acid, and maleic acid, (e) particle size Silicon dioxide (silica SiO_2), titanium oxide (TiO_2), aluminum oxide (alumina Al_2O_3), chromium oxide (Cr_
2O_3), zirconium oxide (ZrO_2), sillimite (Al_2O_3・SiO_2), synthetic mullite (
3Al_2O_3・2SiO_2), zirconia silicate (zircon ZrO_2・SiO_2), silicon nitride (S
One or a mixture of two or more of i_3N_4) 5
~60 parts by weight, a corrosion-resistant product with excellent heat resistance and durability.
A coating composition for creating electrically insulating films.