JPS63207869A - Coating composition forming corrosionproof electrically insulating film having excellent heat resistance and durability - Google Patents

Abstract

PURPOSE:To provide the titled composition containing an alkoxysilane, an acid such as acetic acid, an alcohol, water and an oxide such as SiO2 having specific particle size and useful for forming a corrosionproof film and electrically insulating film having high heat-resistance on the surface of iron, cement, glass, plastics, etc. 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 acetic acid, nitric acid, hydrochloric acid, formic acid, propionic acid or maleic acid and (E) 5-60pts. of SiO2, TiO2, Al2O3, Cr2O3, ZrO2, Al2O3.SiO2, 3Al2O3.2 SiO2, ZrO2.SiO2 and/or Si3N4 having particle diameter of <=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.
A thin film of less than 100g/m is pinhole-free,
There is a demand for materials that are excellent in terms of heat resistance, durability, weather resistance, moisture resistance, corrosion resistance, hardness, etc. That is, 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 IC boards and laminated boards require insulating films with good heat dissipation properties. Therefore, 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, to date, no coating agent with sufficiently satisfactory properties has been developed.
method), glass lining method (PVD method) that involves sintering at high temperatures
There are coating methods such as 100 J
With a thin film of Lm or less, it becomes pinhole-free and provides corrosion protection.
They can be used for 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 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 thickness of 100 gm 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 that has a wide range of uses as an anti-corrosion film because it has excellent heat resistance, weather resistance, and strong anti-corrosion properties against water, seawater, soothing chemicals, and most types of acids. An object of the present invention is to provide a composition.

(Summary of the Invention) In order to achieve the above object, the present invention provides: (a) a silicon compound 10 represented by the general formula R31(OR')> (wherein R is a hydrocarbon group and R' is an alkyl group); ~40 parts by weight, (b) 10 to 80 parts by weight of alcohol, (C) 10 to 80 parts by weight of water, (d) 0.01 to 3 parts of one of acetic acid, nitric acid, hydrochloric acid, formic acid, propionic acid and maleic acid. Weight part.

(e) Silicon dioxide (silica 5iO2), titanium oxide (TiO2) with a particle size of 5 microns or less and 0.1 micron or more
), aluminum oxide (alumina Alz, O:+)
, chromium oxide (Cr, 0.3), zirconium oxide (Z-rO2), silinamite (A120)/Si
oyu), synthetic mullite (3A120J・2SiO2),
It is made by mixing 5 to 60 parts by weight of a mixture of one or more of zirconia silicate (zircon ZrO2*5iO2) and silicon nitride (SitNq).

(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 comprises (a) a silicon compound represented by the general formula R3i (OR' (where R is a hydrocarbon group and R' is an alkyl group)).
~40 parts by weight, (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; (e) particle size of 5 microns or less; Silicon dioxide (SiO2), titanium oxide (T i O
2), aluminum oxide (alumina A12O, J),
Mated chromium (Crt O)), zirconium oxide (Z
rO2), sillimanite (AILOl *5ioL),
Synthetic mullite (3AIZ 0.1 ・2SiO2),
Zirconia silicate (Zircon ZrOs 5iO2),
It has a structure in which 5 to 60 parts by weight of one or a mixture of two or more of silicon nitride (Si7N+) are mixed.

General formula RSi(OR') representing the silicon compound of (a) above
)? R is a hydrocarbon group, such as an alkyl group such as methyl, ethyl, butyl, or an unsaturated hydrocarbon group such as vinylallyl, and R′ is an alkyl group such as methyl, ethyl, 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 when heated. 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, this silicon compound hydrolyzes and turns into a gel.

When the amount added is small, the storage stability of the coating composition is improved, and when it is added in a large amount, it is decreased. The added amount of 10 to 40 parts by weight was determined based on a combination experiment with each component (b) to (e), of which 20 to 3 parts by weight
A range of 0 parts by weight is optimal.

As the alcohol (b), lower aliphatic alcohols are suitable, and inpropyl alcohol is particularly suitable. This alcohol functions as a dispersion medium for the fine particles constituting the above (6).
) is intended to prevent this by a synergistic effect with fine particles.

Tap water or distilled water is used as the water in (C) above, and tap water is usually sufficient, but distilled water is used when a highly purified coating composition is required. This water is (a
) is used to hydrolyze the silicon compound, and the amount added is determined by the relative relationship with the amount of fine particles added in (e), but the amount of addition should be such that there is as little difference as possible between the two amounts. It is preferable to adjust.

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 51L1 or less is because if the particle size exceeds 51Lm, it becomes difficult to form a thin film without pinholes, and the dispersibility decreases. It is. Therefore, the optimum particle size is in the range of 0.1 to 1 l.

Elements (e), such as silicon dioxide, titanium oxide, aluminum oxide, chromium oxide, zirconium oxide, zirnia silicate, sillimanite, synthetic mullite, and silicon nitride, have excellent corrosion resistance.

These materials require high purity depending on the application.
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 you continue to apply more voltage.

Causes dielectric breakdown. If these fine particles are used in amounts below 15 parts by weight, they will promote gelation and reduce storage stability;
If the amount is within the range of 60 parts by weight, the hardness of the coating film and the adhesion to the substrate will be 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. . Furthermore, a colored coating can be formed by using yellow titanium oxide or chromium oxide (green).

When 1 to 20 parts by weight of a commercially available alumina sol is added to a coating composition comprising each of the elements (1) to (e) above, gelation of the composition can be prevented and dispersibility can be improved at the same time. . Further, ultrafine particles of alumina, silica, titania, etc., nonionic surfactants, silane coupling agents, and titanium coupling agents also contribute to improving dispersibility.

When preparing the composition of the present invention, for example, alcoholic water and acid may be added to methyltrimethoxysilane, and component (e) may be added thereto to prepare the composition at once, or (b) to ( e) Mix the ingredients, add methyltrimethoxysilane before use, and age for 3 to 20 hours. This mixture can be made into a uniform and stable dispersion using a high-speed stirrer, ball mill, or other dispersion machine. be able to.

(Effect of the invention) The coating composition having the above structure is coated on the surface of the substrate by a coating method such as brushing, spraying, or dipping to a thickness of 7 to 50 gm in one coat and 20 to 110 g in two coats.
A 0p film can be formed at 80-300°C.
By heating and drying for 10 to 120 minutes, a so-called pinhole-free 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 148
It can be cured by drying for a period of time (7 days) at room temperature. 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. Since the film formed by the present invention is a thin film, the poor thermal conductivity, which is a characteristic of ceramics in general, is not a problem at all. It is possible to form an electrically insulating thin film with good thermal conductivity, which is most ideal as a coating agent for parts. 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 to 100 gm, a highly airtight and hard coating can be obtained.

(2) #It is heat 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, its range of applications as an electrical insulating film extends to other areas.

(4) Metals, glass, ceramics, cement, fibers, paper, plastics (Teflon, polyethylene,
(excluding those without functional groups such as polypropylene), etc.
It can be used with almost all materials.

(5) It has excellent handling properties and can improve workability. In other words, simple degreasing is sufficient for base treatment, and it can be applied at room temperature and cured by heating at 80 to 300°C for 10 to 120 minutes. If this is not possible, it may be cured 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 (Weight) Group
Composition ABC (a) Methyltrimeth 20 25 30 Xysilane (b) Isopropyl 19 18 17
Alcohol (c) Water (tap water) 30 te
20(d) Acetic acid 0.080.
040.05(e) Silicon dioxide 25
15 (particle size 1-1.51L recommended) Titanium oxide (/10.5-1Lm) Chromium pentoxide (
〃 1~aILm) 25 Silicon nitride Ct/ 0.5~lILm) 3
2(f) Alumina sol (A 120, 7 min 20%) 3 Norionic surfactant 1 0.5 1 Silane coupling agent 0.02 Total 100. +100.5'110
Q, oG Next, six steel plates (545C) with a size of 100 x 50 x 10 s/m were prepared, and all of their corners were shaved to eliminate sharp edges and create a rounded appearance. Using these, a test piece was created by the method shown in Specification 1.

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

First coat: Approximately 301 Lm (dry film thickness) was applied and dried at room temperature for 24 hours.

Approximately 401 Lm of the second coating was applied and dried at room temperature for 24 hours.

Third time, the same <401L11 was applied and dried for 24 hours.

4th time: Approximately 401Lm was applied, and after drying at room temperature for 1 hour, 10
The mixture was heated at 0°C for 30 minutes and then at 130°C for 30 minutes.

A discharge type pinhole tester (commercially available) was used to conduct a discharge at 2,000 volts to each of these steel plates to check for pinholes, and pinholes were found in B-1 and A-H. Therefore, I repeated the first and fourth coating methods described above.

After that, we conducted another test and found that the pinhole had disappeared.

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 electronic furnace and allowed to cool naturally.

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

Salt water resistance: Frosted with 4% saline for 480 hours.

Boiled for 120 hours in boiling resistant aqueous tap water.

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

08:00 during 60 days 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.

It was immersed in a 60% sulfuric acid solution for 60 days.

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

(It was immersed in a 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 and 50X50XI
Three aluminum plates and three copper plates of IQ/m size were prepared and a test piece was created using the method of Specification 2.

Table 3 (Parts by weight) Composition
DEFCa) Methyltrimeth 20 27 25 Xysilane (b) Isopropyl 25 20 25
Alcohol (C) water (tap water) 32 20 2
5 (cl) Acetic acid 0.050.04
Q, 02 (e) Aluminum oxide (particle size 0.3-0.6 lm) Silicic acid (tri-3 pm) 25 Zirconia silicon dioxide (l/1-1.51 L layer) 5 Silicon carbide (
/10.3~0.6 ra) 25(f) Alumina sol 32 Thiionic surfactant 10.3 Nonionic surfactant 0.3 Total 100.0
5 100.04 100.8 Specifications 2 Surface treatment method Commercially available alkaline degreaser (water solution pH
II) was used to degrease.

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

First coat: Approximately 20 JL11 (film thickness when dry) was coated and immediately heated at 120° C. for 20 minutes.

2nd time also about 20 p-m Immediately after applying 12
Heated at 0°C for 20 minutes.

Third application: Approximately 20 liters 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.

No. 4 Intensive Example (3) In order to investigate corrosion prevention and cosmetic properties of steel outdoor structures due to the natural environment, two composition examples of H and I shown in Table 7 were prepared.

Table 5 (parts by weight) Composition
HI (a) Methyltrimeth 25 30 Xysilane (b) Isopropyl 18 25 Alcohol (c) Water (tap water) 16 22 (d
) Acetic acid 0.2o.2(e) Titanium oxide yellow 52.5 (particle size 1-1.
5 m) Zirconia silicate 35 17.5 (particle size 1-3 m) (f) Alumina sol nonionic surfactant 0.5 thionic surfactant 10.5 total
100.7 100.7 then 100X50X10
We prepared 6 steel plates (945G) of size 1/2 inch and shaved all the corners to eliminate sharp edges and create a rounded appearance.

Using these, a test piece was created according to the method shown in Specification 3 below.

Specifications 3 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 301 Lm (dry film thickness) of Composition Example H in Table 5 was applied and left outdoors for 24 hours.

Second time: Approximately 40 g of H was applied in the same manner, and the sample was left outdoors for 24 hours.

Third time: Approximately 20 #Lll of the composition shown in Table 5 was applied and left outdoors for 120 hours. 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 6.

Table 6 Test items Test conditions Test result grade
Pencil hardness (JIS method) 5H adhesion ■ Sellotape peeling test No peeling ■ Tensile strength (JIS method) EIO kg/am2 - Water resistance Tap water 60
Days No abnormalities #Saline 4% saline solution 60 days l/〃 4% saline spray 960 hours 〃
Weather resistance Weather resistance test (JIS method) 1000 hours 〃Heat resistance 500℃ held for 120 hours 〃Color fastness The above water resistance to heat resistance No change Tested by visual inspection of the hue after the test The heat resistance of the present invention is as shown above. It can be said that coating compositions for producing durable anti-corrosion films, electrical insulating films and other functional films have excellent properties and are very effective for industrial use.

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.