JP3131038B2 - Binder composition for casting, composition for casting, and method for producing casting mold or core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a casting mold or a core (hereinafter abbreviated as a mold) having excellent properties such as strength and surface stability, and a composition used therefor.

2. Description of the Related Art Conventionally, as a method for rapidly and efficiently producing a casting mold that does not generate irritating acid gas at the time of pouring, for example, a potassium-alkaline phenol-formaldehyde resin specific to a granular refractory aggregate and A technique described in JP-A-58-154434, in which a silane compound is mixed and cured with an ester catalyst, is known.

[0002]

However, the mold formed by such a conventionally known method has low strength and has a rough surface, that is, poor surface stability. Further, the disintegration of the mold after the completion of the casting is poor. For this reason, the quality of the casting is deteriorated. The present invention provides a method for producing a casting mold having high mold strength and surface stability of the mold, and also excellent mold disintegration after completion of casting, and a binder composition for casting and a casting composition used therefor. It is an object to provide a molding composition.

[0003]

In order to achieve the above object, a binder composition for casting according to the present invention has the general formula HC
The following component (A), which can be cured by vapor or aerosol of a curing agent containing a formate ester represented by OOR (where R represents an alkyl group having 1 to 3 carbon atoms),
(B), (C) and, if necessary, a solvent. (A) a silane compound. (B) a water-soluble phenol resin. (C) polyvinyl alcohol. The composition for casting and molding of the present invention comprises the following components, which can be cured by a vapor or aerosol of a curing agent containing a formate ester represented by the general formula HCOOR (where R represents an alkyl group having 1 to 3 carbon atoms). (A), (B), (C),
(D) and, if necessary, a solvent. (A) a silane compound. (B) a water-soluble phenol resin. (C) polyvinyl alcohol. (D) Granular refractory aggregate. The method for producing a casting mold of the present invention comprises the following component (A):
A solution of the binder composition containing (B) and (C) and (D) a granular refractory aggregate are mixed, and the mixture is molded by taking a core or in a mold frame and then molding The product is cured by passing through a vapor or aerosol of a curing agent containing a formate ester represented by the general formula HCOOR (where R represents an alkyl group having 1 to 3 carbon atoms). (A) a silane compound. (B) a water-soluble phenol resin. (C) polyvinyl alcohol.

[0004] As the granular refractory aggregate in the present invention,
Silica sand, chromite sand, zircon sand, olivine sand, and other refractory granular sands conventionally used for mold casting, as well as clay sand and recycled sand, can also be used. The water-soluble phenol resin used in the present invention is a resin curable with an organic ester, such as phenol, cresol, resylcinol, xylenol, bisphenol A, cumylphenol, nonylphenol, butylphenol,
Phenylphenol, ethylphenol, octylphenol, amylphenol, naphthol, bisphenol F, bisphenol C, catechol, hydroquinone, pyrogallol, phloroglucin, lignin, bisphenol A residue, cresol residue, chlorophenol,
Phenols, including dichlorophenol and other substituted phenols, formaldehyde, acetaldehyde,
Phenolic resins obtained by reaction with furfural aldehyde and a mixture of aldehydes and the like are included. Suitable alkaline substances used for the condensation of these phenolic resins are sodium hydroxide, potassium hydroxide, lithium hydroxide and mixtures thereof, with potassium hydroxide being most preferred. As the water-soluble phenol resin in the present invention, a potassium alkaline phenol-formaldehyde resin is preferable, and it is usually used as a solution having a solid content of 50 to 75% by weight, particularly as an aqueous solution. The polyvinyl alcohol in the present invention is not limited in its degree of polymerization and saponification degree, and any known ones can be used,
The saponification degree is preferably in the range of 80 to 99% from the viewpoint of solubility in the solvent and the gelling property, and the polymerization degree is preferably 2500 or less from the viewpoint of the viscosity of the solution. Furthermore, the blending amount of the polyvinyl alcohol, from the viewpoint of the viscosity and the mold strength when the binder composition solution is used,
The range is preferably 0.1 to 10 parts by weight, and more preferably 0.5 to 10 parts by weight, based on 100 parts by weight (as solid content) of the water-soluble phenol resin.
A range of from 5 to 5 parts by weight is particularly preferred.

[0005] Polyvinyl alcohol may be blended with the produced water-soluble phenolic resin, or may be blended in advance when producing the water-soluble phenolic resin. The silane compound in the present invention is preferably used in the range of 0.05 to 3% by weight based on the resin solution in order to improve the strength of the forming template. For example, γ-glycidoxypropyl tri Methoxysilane, γ-aminopropyltriethoxysilane and the like can be mentioned.

[0006] The casting mold is manufactured by mixing the granular refractory aggregate and the binder composition by a conventional method and molding. As the core and mold frame having good air permeability, conventional types used in a conventional gas removal method can be used. In a mold in which a composition prepared by blending the particulate refractory aggregate of the present invention and an organic solvent of the binder composition, a solution such as water, a formate ester such as methyl formate is generally used as an inert carrier gas. As vapor or aerosol in the
Cured by passing and absorbing at room temperature or slightly higher temperature. The inert carrier gas is, for example, air,
Nitrogen or carbon dioxide gas. The amount of the formate curing agent used is preferably in the range of 5 to 60% by weight based on the resin solution. The time required for absorption of the curing agent depends on the size and shape of the mold and the type of resin, but in most cases ranges from several seconds to several minutes. To prevent damage to the mold when removing the mold from the frame after absorbing the curing agent,
It is preferable to leave the mold from the frame after leaving it for a sufficient time. This time can be reduced by passing a heated inert carrier gas through the mold. The binder composition solution of the present invention has a content of 0.5 to the granular refractory aggregate.
It is preferred to mix in the range of -8% by weight. From the viewpoint of the strength of the molding mold, it is more preferable to mix in a range of 1 to 3% by weight.

[0007]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. In Examples and Comparative Examples,
Means "parts by weight", and "%" means "% by weight". Examples 1 to 9 and Comparative Examples 1 to 4 Preparation of Binder Composition An aqueous solution containing 27.2 parts of 100% phenol and 10 parts of KOH was mixed and dissolved. 37% of 46.9 parts in this
An aqueous formaldehyde solution was further added (formaldehyde: phenol molar ratio 2.0: 1). The mixture solution was heated under reflux for 3 hours and then cooled to obtain a solid content of 5%.
An aqueous solution of 0% potassium alkaline phenol-formaldehyde resin was prepared. In this potassium alkaline phenol / formaldehyde resin aqueous solution, 100 parts of this resin (as solid content) were mixed with a 15% or 30% aqueous polyvinyl alcohol solution having the compounding amount shown in Tables 1 and 2, and γ-glycidoxypropyltrimethoxy. One part of silane was added and mixed well to prepare a binder composition. In Table 1, a 15% aqueous solution of polyvinyl alcohol is blended, and the blended amount is shown in terms of solid content. In Table 1, polyvinyl alcohol GL-05 has a degree of polymerization of about 500 and a saponification degree of 88%, KH-20 has a degree of polymerization of about 2,000 and 80%, and NL-05 has a degree of polymerization of about 500 and a degree of saponification of 99.
%, NM-14 is a polymerization degree of about 1400, a saponification degree of 99%,
PVA-217 has a degree of polymerization of about 1700 and a degree of saponification of 8
8%. In Table 2, in Example 9, a 30% aqueous solution of polyvinyl alcohol was blended, in other examples, a 15% aqueous solution of polyvinyl alcohol was blended, and in Comparative Examples, the amounts corresponded to the amounts added in Comparative Examples. A quantity of water was added. [Method for measuring physical properties] The viscosity was measured at 25 ° C using a B-type viscometer.
Was measured. The solid content was measured by heating 2.0 ± 0.1 g of the sample at 100 ° C. for 3 hours in an air circulation furnace.

Production of Mold Test Specimen Fremantle silica sand and the binder composition solution produced as described above are blended and mixed in an amount such that the binder composition has a solid content of 2.0% with respect to the silica sand. Thus, a composition for casting was prepared. A mixture of the composition for casting and molding in a mold frame by a sand rammer method is allowed to act on a mixed gas of methyl formate and air at room temperature to obtain a 50 m diameter.
m, a mold test piece having a height of 50 mm was produced. Tables 1 and 2 show the performance of the manufactured mold test pieces.

[Performance Test Method] Compressive strength After the mold test piece was manufactured, the compressive strength (kgf / cm ² ) of the mold test piece was measured after curing for 3 hours or 24 hours after curing at room temperature (20 ° C.) and 50% relative temperature. 2. Surface stability A mold specimen was placed on a 10-mesh sieve at room temperature (20 ° C.) for 2 minutes.
After shaking for a minute, the residual ratio of the mold test piece remaining on the sieve is indicated by (weight)%. 3. Hot surface stability After the mold test pieces were heated at 400 ° C., 600 ° C. or 800 ° C. for 1 minute each, they were shaken on a 10-mesh sieve for 2 minutes, and the residual ratio of the mold test pieces remaining on the respective sieves Is displayed in (weight)%. 4. Hot (compression) strength After heating the mold specimen at 700 ° C. for 5 minutes, immediately measure the compression strength (kgf / cm ² ) of the mold specimen. 5. Residual strength After heating the mold specimen at 700 ° C. for 5 minutes,
℃) for 24 hours, and the compressive strength (kgf
/ Cm ² ).

[0010]

[Table 1]

[Table 2]

[0011]

As described above, the mold molded according to the present invention has significantly higher compressive strength and hot (compressed) than the conventional mold.
It has strength and surface stability, and is even more excellent in the disintegration of the mold after the casting is completed by pouring the molten metal. Therefore, it has become possible to manufacture high-precision castings such as automotive castings with high quality and efficiency. Furthermore, since the surface stability of the mold produced according to the present invention is excellent, the mold used in the conventional mold for producing a casting, which requires a precise surface, becomes unnecessary.

Continued on the front page (72) Inventor Morio Shiokawa 7-43, Oguro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Hodogaya Ashland Co., Ltd. Technical Research Institute (58) Field surveyed (Int. Cl. ⁷ , DB name) B22C 1 / 00-1/26

Claims (3)

(57) [Claims] 1. A compound of the general formula HCOOR (where R is 1 carbon atom)
Represents an alkyl group of 1 to 3. ) Can be cured by the vapor or aerosol of a curing agent containing a formate shown in
A binder composition for casting and molding comprising the following components (A), (B) and (C) and, if necessary, a solvent. (A) a silane compound. (B) a water-soluble phenol resin. (C) polyvinyl alcohol. 2. A compound of the general formula HCOOR (where R is 1 carbon atom)
Represents an alkyl group of 1 to 3. ) Can be cured by the vapor or aerosol of a curing agent containing a formate shown in
A composition for casting and molding comprising the following components (A), (B), (C) and (D) and, if necessary, a solvent. (A) a silane compound. (B) a water-soluble phenol resin. (C) polyvinyl alcohol. (D) Granular refractory aggregate. 3. A solution of a binder composition containing the following components (A), (B) and (C) and (D) a granular refractory aggregate are mixed, and the mixture is cored or molded. And molded into the molded product, and then the molded product has the general formula HCOOR (R
Represents an alkyl group having 1 to 3 carbon atoms. B) passing through a vapor or aerosol of a curing agent containing a formate ester and curing the mixture to cure the casting mold or core. (A) a silane compound. (B) a water-soluble phenol resin. (C) polyvinyl alcohol.