JPS6312672A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition capable of keeping high adhesivity to a substrate even after quick cooling and heating cycles and having excellent lubricity and mold-release property, by dispersing and dissolving a polymethallocarbosilane, boron nitride powder and an inorganic filler in an organic solvent. CONSTITUTION:The objective composition can be produced by dispersing and dissolving (A) a polymethallocarbosilane [preferably a polymer having a molecular weight of 400-50,000 and composed of the carbosilane bond unit of formula (R1 and R2 are lower alkyl, phenyl or H) and at least one kind of metalloxane bond unit of formula -(M-O)- (M is Ti, Zr, Cr or Mo), wherein said bonding units are randomly bonded with each other in the skeleton of polymer main chain], (B) boron nitride powder (preferably having a particle diameter of <=10mum) and (C) an inorganic filler (e.g. silicon carbide, silicon nitride, silicon oxide, etc., preferably having particle diameter of <=10mum) in (D) an organic solvent.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a coating composition, particularly a coating composition having excellent adhesion and mold releasability, consisting of a polymetallocarbosilane solution containing boron nitride in a specific proportion. relating to things.

(Prior art and its problems) Boron nitride has excellent thermal conductivity and a small coefficient of thermal expansion, so it can withstand exposure to high temperatures or thermal shock, and is resistant to getting wet with molten metals, salts, and glass.

Because it is resistant to corrosion, it is used as a mold release material for glass molding and die casting.

At this time, as a method of using mold release material.

(1) A method of using boron nitride as it is as a powder or compact.

(2) A state in which boron nitride powder is dispersed in a solvent, etc.
Alternatively, there is a method of adding a binder to this, applying it to a base material, and baking it. However, the powder (1) has poor adhesion.

A good coating film cannot be formed, and the molded product is expensive and impractical. Next, in method (2), when the boron nitride dispersion is applied to the substrate and then baked, the coating film will crack or peel if exposed to high temperatures exceeding 500°C.
Even at low temperatures below C, unless the rate of temperature rise and fall is reduced,
Construction is extremely difficult as blisters and cracks occur. Moreover, the above-mentioned drawbacks can be alleviated to some extent by adding a glaze or silicone resin as a binder to this dispersion.

The addition of glaze impairs the original performance of lubricity and mold release, and silicone resin has a heat resistance of only 300°C at most, and if this temperature is exceeded during baking or use, weight loss due to thermal decomposition is significant. As a result, cracks and pinholes occur in the paint film, which significantly reduces the adhesion of the paint film.

(Purpose of the invention) The present invention aims to solve these drawbacks, and has excellent adhesion, lubricity, and mold releasability, and is also resistant to peeling even when used or baked with rapid cooling/heating cycles. The aim is to provide a coating composition that does not generate

(Summary of the Invention) The present invention is a coating composition prepared by dispersing and dissolving polymetallocarbosila/boron nitride powder and an inorganic filler in an organic solvent.

(Detailed Description of the Invention) The amount of boron nitride powder used in the present invention is preferably 5 to 50% by weight based on the total amount of the inorganic filler in the powder. The adhesion to the substrate of the product decreases, resulting in peeling, cracking, etc., and if the amount is too small, the lubrication and mold releasability of the resulting composition decrease.

The particle size of boron nitride has a large effect on the adhesion to the base material, so it is preferably 10 μm or less.

Inorganic fillers include silicon carbide and silicon nitride.

Powders of silicon oxide, titanium oxide, aluminum oxide, etc. can be used, and the particle size thereof is preferably 10 μm or less from the viewpoint of adhesion to the base material.

The amount of polymetallocarbosilane used is preferably 50 to 200 parts by weight based on the total of 100 parts by weight of boron nitride and inorganic filler. If the amount of polymetallocarbosilane used is too large, blistering of the coating film will occur during baking, and if the amount used is too small, the adhesion of the coating film to the substrate will be reduced.

The polymetallocarbosilane used in the present invention is shown below (A
) and at least one of the following (
Consisting of the metalloxane bonding unit of B).

(A): R1 (-8i-C!H2-)- (in the formula, R1 and R2 may be the same or different and independently represent an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a hydrogen atom) (B): (-M-0-) (In the formula, 1M represents at least one element selected from the group consisting of Ti, Zr, Mo, and Or, and in some cases, at least a portion of each element is on the side. 1 carbon number as chain group
-4 alkoxy group or at least one phenyl group. ) A polymer in which the bonding units of (A) and (B) are randomly bonded in the main chain skeleton, and/or at least a portion of the silicon atoms of the bonding units of (A) are the bonding units of (B). A polymer in which the polycarbosilane moiety obtained by the chaining of the bonding units of (4) is crosslinked by the bonding units of (B), which are bonded to each of the above elements through oxygen atoms. be. The total number of binding units of said GA) versus said (B
) is preferably in the range of 1-1 to 10:1. still.

The number average molecular weight of polymetallocarbosilane is 400 to 50
Preferably, it is 000.

The polymetallocarbosilane preferably contains a silicone resin in order to improve the film-forming properties of the composition.

As the silicone resin, any of silicone oil, silicone face, and silicone rubber can be used. The blending amount of the silicone resin is 9900 parts by weight or less, especially 10 parts by weight per 100 parts by weight of polymetallocarbosilane.
It is preferable that it is 200 parts by weight.

The amount of organic solvent used is 1 part by weight per 100 parts by weight of boron nitride and inorganic filler in order to facilitate mixing and dispersion of boron nitride and inorganic filler and to facilitate painting work.
It is preferably 0 parts by weight or more. There is no particular restriction on the upper limit of the amount of organic solvent used, but if it is too large, the concentration of polymetallocarbosilane will decrease relatively, so 1 part by weight per 100 parts by weight of boron nitride and inorganic filler.
The amount is preferably 0.00 parts by weight or less. As the solvent, aromatic hydrocarbon solvents such as toluene and xylene are preferably used.

The coating composition of the present invention can be prepared by mixing boron nitride, inorganic filler, polymetallocarbosilane, and organic solvent in a conventional mixer for several hours.

The coating composition thus obtained is made of iron.

The coating is applied to a base material such as alumina or graphite using an appropriate method such as brush coating or a coating machine such as spraying.

A coating film with excellent performance can be obtained by drying at room temperature or by baking at a high temperature after drying at room temperature.

(Effect of the invention) The coating film obtained from the coating composition according to the invention.

Good adhesion to the base material even under rapid heating and cooling cycles.

It has excellent lubrication and mold release properties, so it can be used for castings, aluminum,
It can be used as a mold release agent for guicasting zinc and glass molding.

(Example) An example of the present invention will be shown below to further explain the present invention. In the following, "chi" and "parts" mean "% by weight" and "parts by weight", respectively.

Reference Example 1 2.51 g of anhydrous xylene and 4002 g of sodium were heated in a nitrogen gas stream to the boiling point of xylene, and 1 t of dimethyldichlorosilane was added dropwise over 1 hour.

After the dropwise addition was completed, the mixture was heated under reflux for 10 hours to form a precipitate.

The precipitate was filtered, washed with methanol and then water,
Polydimethylsilane 4202 as a white powder was obtained.

On the other hand, diphenyldichlorosilane 7591 and boric acid 12
42 in n-butyl ether under nitrogen gas atmosphere, 10
A 5-0 polyborodiphenylsiloxane was obtained by heating at a temperature of 0 to 120°C and further heating the produced white resinous material at 400°C in vacuum for 1 hour.

Next, 0.22 of the above polyborodiphenylsiloxane was added to the above polydimethylsilane 4002 and mixed, and the mixture was heated to 350°C under a nitrogen stream in a 2t quartz tube equipped with a reflux tube.
and polymerize for 3 hours.

An organosilicon polymer was obtained.

This organosilicon polymer 400f and titanium tetraisopropoxide 2002 were mixed with xylene 4t as a reaction solvent,
The reaction was carried out under a nitrogen gas atmosphere at 130'C for 1 hour with stirring. After distilling off the xylene, the reaction was further carried out at 300°C for 10 hours to obtain an organometallic crosslinked polymer containing silicon and titanium. Its number average molecular weight was 1165 when measured by vapor pressure osmosis method.

Gel permeation chromatography and infrared absorption spectroscopy revealed that the 5i-H bonds in the organosilicon polymer have partially disappeared, and the silicon atoms in this part have been replaced by the titanium of titanium tetraisopropoxide. atoms and oxygen atoms, so that some of the organosilicon polymers have -o -T1(003H))3 groups in their side chains, and some of the organosilicon polymers have +Ti-0+ bonds. It was a polytitanocarbosilane crosslinked with This polymer (−
8i-]H2+ bonding units versus the total number of -Ti-0- bonding units was confirmed to be 1.

Example 1 For 100 parts of a mixture of 15% boron nitride (average particle size 3 μm) and 85% silicon oxide (average particle size 2 μm),
100 parts of polytitanocarbosilane and 100 parts of xylene from Reference Example 1 were uniformly mixed in a ball mill. This was applied to an iron plate with a brush to a thickness of 100 μm, and after drying at room temperature,
The sample was placed in an open oven at °C, baked for 30 minutes, and then immediately cooled to room temperature.

Next, this coated steel plate is immersed in a pure aluminum melt at 600°C for 10 minutes, and then pulled up to test the corrosion resistance and wettability of the coating film against the aluminum melt (the aluminum melt adheres to the surface of the coating when it is pulled up). ), but no cracks, peeling, or wetting was observed.

Comparative Example 1 Example 1 except that 100 parts of silicone resin (straight silicone) was used instead of polytitanocarbosilane.
When a test was conducted on a coated steel plate obtained in the same manner as above, the coating film cracked and peeled off in some areas, and wetting of the aluminum was observed in the peeled areas.

Example 2 200 parts of the polytitanocarbosilane of Reference Example 1 and 20 parts of toluene were added to 100 parts of a mixture of 15% boron nitride (average particle size 6 μm) and 85% silicon nitride (average particle size 1 μm).
0 parts were uniformly mixed using a high speed mixer. This graphite rod (
20cm diameter, 200cm long) with a brush coating to a thickness of 0.31t1m, and dried at room temperature.

Baking was carried out in the open at 200°C for 2 hours. Next, this base material was immersed in the glass melt for 10 minutes, and then the base material was pulled up and the condition of the coating film was observed, but no cracks or peeling were observed, and no wetting of the glass was observed.

Claims (2)

[Claims] (1) A coating composition characterized by dispersing and dissolving polymetallocarbosilane, boron nitride powder, and an inorganic filler in an organic solvent. (2) Polymetallocarbosilane consists of the carbosilane bond unit shown below (A) and at least one metalloxane bond unit shown below (B), (A): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1 and R_2 may be the same or different and independently represent a lower alkyl group, a phenyl group, or a hydrogen atom) (B): -(M-O)- (However, M is a group consisting of Ti, Zr, Cr, and Mo. at least one element selected from the group consisting of (A) and (B) each of the above (A) and (B). A polymer in which the bonding units are randomly bonded in the main chain skeleton, and/or at least a portion of the silicon atoms in the bonding unit (A) are connected to each of the elements in the bonding unit (B) via an oxygen atom. is a polymer in which the polycarbosilane moiety obtained by the chaining of the bonding units of (A) is crosslinked by the bonding units of (B), and the total number of bonding units of (A) to the ( B
Coating composition according to claim 1, characterized in that the ratio of the total number of bonding units in ) is in the range of 1:1 to 10:1 and the number average molecular weight is 400 to 50,000. .