JPH0645053B2 - Coating agent composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an alcoholic coating composition for coating on the surface of a mold.

[Conventional technology and problems]

When manufacturing a casting, if the molten metal at a high temperature comes into direct contact with the surface of the mold, it causes seizure or graining, which may roughen the casting surface or cause defective sand removal. In order to create a smooth casting surface and prevent skin sand from burning, a mold coating agent is applied to the surface of the mold.

This mold coating agent is a mixture of a refractory material such as zirconium silicate, graphite, alumina, silica, magnesia and a binder, and other substances mixed in a solvent such as water or alcohol, and water is used as the solvent. Is referred to as an aqueous coating agent, and an agent using alcohol as a solvent is referred to as an alcoholic coating agent.

However, in the conventional case, the alcoholic mold coating agent has a poor brush elongation when applied to the mold surface, and the solvent (alcohol) has a large penetration into the mold, which causes gas defects and
There is a problem that the strength of the mold is deteriorated.

[Means for solving problems]

As a result of earnest research to solve the above problems, the present inventors have
The present invention has been completed by finding a mold coating composition which has good brush elongation at the time of application, excellent workability, and suppresses solvent penetration into a mold.

That is, the present invention is based on 100 parts by weight of refractory, 0.5 to 3 parts by weight of organic binder, 1 to 5 parts by weight of organic bentonite, 30 to 80 parts by weight of alcohol having 4 or less carbon atoms, and compatible with organic bentonite. The present invention relates to a coating agent composition containing 0.5 to 10 parts by weight of a good solvent.

Hereinafter, each constituent component of the coating composition of the present invention will be described in detail.

The refractory of is to enhance the fire resistance of the mold and core surface, for example, powder of zircon silicate, graphite, alumina, silica, mullite, sheamot, chromite, olivine, etc., alone or in combination of two or more. Things are used.

The organic binder of, is applied in order to apply a alcoholic coating agent on the mold, after ignition drying, to maintain a constant coating strength, phenol, rosin is a typical binder resin is there.

The organic binder is added in an amount of 0.5 to 3 parts by weight, more preferably 0.8 to 2 parts by weight, based on 100 parts by weight of the refractory material. If the amount of the organic binder is less than 0.5 part by weight, the adhesive strength with the aggregate will be insufficient and a constant coating strength cannot be maintained. Further, if it exceeds 3 parts by weight, gas defects become a problem due to thermal decomposition at the time of pouring, and unnecessarily high strength is unpreferable.

The organic bentonite is a montmorillonite in which the exchangeable cation is replaced with an organic cation compound or a polar compound and has a property of swelling various organic solvents.

The organic bentonite is mixed in an amount of 1 to 5 parts by weight, preferably 2 to 3 parts by weight, based on 100 parts by weight of the refractory material. If the blending amount of the organic bentonite is less than 1 part by weight, the adhesive strength in hot time is insufficient, and if it exceeds 5 parts by weight, gas defects become a problem due to thermal decomposition during pouring.

Alcohol having 4 or less carbon atoms is a solvent for brushing or spray-coating a refractory material into a slurry, and includes alcohols such as methanol, ethanol, isopropanol, butanol, etc., which may be used alone or in combination of two or more. Used.

The alcohol is blended in an amount of 30 to 80 parts by weight with respect to 100 parts by weight of the refractory material. If the blending amount of the alcohol is less than 30 parts by weight, the mold coating agent becomes too hard and becomes difficult to handle. On the other hand, if it exceeds 80 parts by weight, the coating agent becomes too thin to be handled easily, and it is economically disadvantageous.

The solvent having a good compatibility with the organic bentonite is a solvent necessary for efficiently swelling the organic bentonite and increasing the viscosity of the alcohol coating liquid, and for example, those shown in the following (a) to (e) are preferable.

(a) An aromatic solvent such as toluene or xylene.

(b) Hydrocarbon-based solvent having 5 to 10 carbon atoms such as hexane, pentane and petroleum fraction.

(c) general formula R ₁ -OR ₂ such as diethyl ether and diisopropyl ether (in the formula, R ₁ : C ₁ -C ₆ alkyl group, R ₂ : C ₁
~ C ₆ alkyl group) represented by an ether solvent.

(d) General formula of methyl isobutyl ketone, etc. (In the formula, R ₁ : C ₁ -C ₆ alkyl group, R ₂ : C ₁ -C ₆ alkyl group).

(e) General formula such as ethyl acetate (In the formula, R ₁ : C ₁ -C ₆ alkyl group, R ₂ : C ₁ -C ₆ alkyl group).

These solvents are 0.5 to 10 parts by weight with respect to 100 parts by weight of refractory,
More preferably, 2 to 5 parts by weight are blended. If the blending amount of these solvents is less than 0.5 part by weight, the swelling of the organic bentonite is insufficient, the brush elongation is poor, and the amount of alcohol remaining in the mold is large. On the other hand, if the amount exceeds 10 parts by weight, the amount is too large to swell the organic bentonite, which causes a cost increase.

A refractory for coating, an organic binder, an organic bentonite, and a solvent having a high compatibility with the organic bentonite are mixed with an alcohol having 4 or less carbon atoms to form a slurry to obtain a coating composition.

The mold coating composition obtained as described above is applied to the surface of the mold or core by brush coating, spraying or dipping. After application, the solvent is burned by ignition to dry and cure.

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 and 2 and Comparative Example 1 The components were kneaded in a kneading machine for 1 hour in the proportions shown in Table 1 to obtain uniform coating agents.

The following measurements were performed using the coating agent prepared in this way.

(1) Measurement of residual amount of solvent in mold A test mold of 90 mmφ × 120 mmH was prepared by adding 0.8 parts by weight of furan resin and 0.32 parts by weight of catalyst to 100 parts by weight of No. 5 silica sand (recycled sand). After this mold was dried at 130 ° C. for 3 hours, the mold coating agents shown in Table 1 were uniformly applied with a brush, followed by igniting and drying, and the weight after extinguishing was measured (xg
And).

At this time, 130 ℃ × 3 to determine the amount of solvent remaining inside the mold.
After drying with Hr and cooling, the weight was measured (yg).

The amount wg of alcohol remaining in the mold is determined by w = xy.

(2) Measurement of brush extension length at the time of application On a flat mold cured with furan resin, the coating agent shown in Table 1 was included with the brush, and when the sagging stopped, it was applied linearly. The length from the starting point to the point where the brush eyes appeared was measured.

The experimental results are shown in Table-2.

From the experimental results shown in Table-2, in Example 1 and Example 2, the result was obtained that the residual amount of alcohol in the mold was reduced and the brush elongation was also improved.

〔The invention's effect〕

As is clear from the above description and experimental results, the coating composition of the present invention in which a refractory material, an organic binder, an organic bentonite, an alcohol having a carbon number of 4 or less, and an organic bentonite and a solvent having good compatibility are combined, The residual amount of alcohol in the mold can be reduced, and the brush elongation is also good, so that the coating workability is improved and excellent results are obtained.

Claims (2)

[Claims] 1. 100 parts by weight of a refractory, 0.5 to 3 parts by weight of an organic binder, 1 to 5 parts by weight of organic bentonite, 30 to 80 parts by weight of an alcohol having a carbon number of 4 or less, and compatibility with organic bentonite. A coating composition comprising 0.5 to 10 parts by weight of a good solvent. 2. A solvent having good compatibility with organic bentonite is (a) an aromatic solvent, (b) a hydrocarbon solvent having 5 to 10 carbon atoms, (c) a general formula R ₁ -OR ₂ (wherein , R ₁ : a C _{1 to} C ₆ alkyl group,
R _2: ether solvents represented by the alkyl group) in C ₁ ~C _6, (d) the formula (In the formula, R ₁ : C ₁ -C ₆ alkyl group, R ₂ : C ₁ -C ₆ alkyl group), a ketone solvent represented by: (e) General formula (In the formula, R ₁ : C ₁ -C ₆ alkyl group, R ₂ : C ₁ -C ₆ alkyl group) The ester solvent represented by The coating composition according to item 1.