JP3165262B2 - Binder composition for casting, composition for casting, and method for producing casting mold - 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 and a core (hereinafter abbreviated as a mold throughout the present specification) which are excellent in performance such as strength and surface stability, and to be used therefor. Composition.

2. Description of the Related Art Heretofore, as a composition for rapidly and efficiently producing a casting mold which does not generate irritating acid gas at the time of casting, for example, potassium alkali which can be hardened with a liquid ester hardener is used. A resin composition containing a phenol / formaldehyde resin and a silane compound is known (see JP-A-1-40136).

[0002]

However, a mold produced by using such a conventionally known resin composition,
Low strength. 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 has a remarkably high mold strength and mold surface stability, and a method for producing a casting mold excellent in mold disintegration after completion of casting, and a binder composition for casting used in the method and An object of the present invention is to provide a composition for casting.

[0003]

In order to achieve the above object, a binder composition for liquid organic acid ester curable casting molding of the present invention comprises a water-soluble phenol resin, polyvinyl alcohol, a silane compound and Wherein the solvent is contained. The composition for casting and molding of the present invention is characterized by containing a water-soluble phenol resin, polyvinyl alcohol, a silane compound, a liquid organic acid ester-based curing agent, a granular refractory aggregate, and, if necessary, a solvent. The method for producing a casting mold of the present invention comprises a solution of a binder composition containing a water-soluble phenolic resin, polyvinyl alcohol, a silane compound and a solvent, a liquid organic acid ester-based curing agent, and a granular refractory aggregate. It is characterized by mixing, storing the mixture in a mold frame, molding and curing.

[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 phenolic resin used in the present invention is a resin curable with a liquid organic acid ester-based curing agent, such as phenol, cresol, resorcinol, xylenol, bisphenol A, cumylphenol, nonylphenol,
Butylphenol, phenylphenol, ethylphenol, octylphenol, amylphenol, naphthol, bisphenol F, bisphenol C, catechol, hydroquinone, pyrogallol, phloroglucin,
Phenol resins obtained by reacting phenols including lignin, bisphenol A residue, cresol residue, chlorophenol, dichlorophenol, and other substituted phenols with formaldehyde, acetaldehyde, furfural aldehyde, and a mixture of aldehydes, and the like. 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. The weight average molecular weight of this water-soluble phenol resin is preferably in the range of 800 to 2,000. As the water-soluble phenol resin in the present invention, a potassium alkaline phenol-formaldehyde resin is preferable, and usually, a solution having a solid content of 50 to 75% by weight,
In particular, it is used as an aqueous solution.

[0005] The polyvinyl alcohol in the present invention is
The degree of polymerization and the degree of saponification are not limited, and any known one can be used, but the degree of saponification is in the range of 80 to 99% from the viewpoint of solubility in the solvent and gelation. The polymerization degree is preferably 2500 or less from the viewpoint of the viscosity of the solution. Furthermore, the blending amount of polyvinyl alcohol is determined based on the viscosity of the binder composition solution and the strength of the mold.
The range is preferably 0.1 to 10 parts by weight, particularly preferably 0.5 to 5 parts by weight, based on 0 parts by weight (as solid content). The polyvinyl alcohol may be blended with the produced water-soluble phenol resin, or may be blended in advance at the time of producing the water-soluble phenol 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.

The organic acid ester as the curing agent in the present invention is a liquid ester compound excluding methyl formate, ethyl formate and propyl formate, and has a boiling point of 10 at room temperature.
0 ° C or higher. Specifically, an ester compound of a monohydric or polyhydric alcohol and a carboxylic acid, particularly one having 1 carbon atom
An ester compound of a monohydric or polyhydric alcohol having 10 to 10 and a carboxylic acid having 2 to 10 carbon atoms, a lactone compound, and a carbonate compound can be given. More specifically, for example, ethyl acetate, dimethyl adipate,
Dimethyl succinate, ethylene glycol diacetate,
Monoacetin, diacetin, triacetin, ethylene carbonate, γ-butyrolactone, propiolactone, ε-caprolactone, or a mixture thereof. The amount of the liquid organic acid ester-based curing agent used is
5 to 110% by weight, especially 2%, based on the solution of the binder composition
A range of 0 to 60% by weight is preferred.

The casting mold is manufactured by mixing a granular refractory aggregate, a solution of a binder composition, and a liquid organic acid ester-based curing agent by a conventional method, followed by molding. For the core removal and the mold frame, a conventional type conventionally used can also be used. An organic solvent of the granular refractory aggregate of the present invention and the binder composition, a mold formed by mixing a solution such as water and a liquid organic acid ester-based curing agent is molded at room temperature or a slightly higher temperature. And let it cure for a certain period of time. The curing time depends on the size and shape of the mold and the type of the resin, but is usually in the range of 1 hour to 24 hours. The binder composition solution of the present invention is preferably blended in the range of 0.5 to 8% by weight with respect to the granular refractory aggregate. In terms of the strength of the mold,
It is particularly preferable to mix in the range of 1 to 3% by weight.

[0008]

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". Preparation of binder compositions in Examples 1 to 3 and Comparative Examples 1 and 2 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, 10% or 30% polyvinyl alcohol aqueous solution (G
L-05: polymerization degree 500, saponification degree 88%) and one part of γ-glycidoxypropyltrimethoxysilane were added and mixed well to prepare a binder composition. In Table 1,
In Example 1, a 10% aqueous solution of polyvinyl alcohol was added. In other examples, an aqueous solution of 30% polyvinyl alcohol was added. In Comparative Example 1, nothing else was added. In Comparative Example 2, the aqueous solution of polyvinyl alcohol in Example 1 was added. Water was added in an amount corresponding to the amount added. [Method for Measuring Physical Properties] The solid content was measured by heating 2.0 ± 0.1 g of a sample at 100 ° C. for 3 hours in an air circulation furnace.

Production of mold test piece To 1000 parts of Fremantle silica sand, 4 parts of triacetin as a hardening agent was added and kneaded for 1 minute. Further, 20 parts of the solution of the binder composition produced as described above was added thereto, and further added. The mixture was kneaded for 1 minute to prepare a composition for casting and molding. The composition for casting and molding was stored in a wooden form and molded,
It was left for 4 hours to produce a mold test piece having a diameter of 50 mm and a height of 50 mm. Table 1 shows 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 at normal 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 piece was heated at 700 ° C. for 20 seconds, it was shaken on a 10-mesh sieve for 1 minute, and the residual ratio of the mold test piece remaining on the sieve was indicated by (weight)%. . 4. Residual strength After heating the mold specimen at 700 ° C. for 5 minutes,
℃) for 24 hours, and the compressive strength (kgf
/ Cm ² ).

[0011]

[Table 1]

[0012]

As described above, the mold molded according to the present invention has remarkably high compressive strength and, at the same time, the residual strength can be reduced. The disintegration of the mold is much better, and the surface stability and hot surface stability are also good. For this reason, it has become possible to produce a large-sized precision casting with high quality and efficiency, which requires high compressive strength and requires easy mold release after casting.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Morio Shiokawa 7-43, Oguro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Hodogaya Ashland Co., Ltd. Technical Research Institute (56) References JP-A-6-579 (JP, A JP-A-4-284940 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22C 1/00-1/26

Claims (3)

(57) [Claims] 1. A liquid organic acid ester curable binder composition for casting, which comprises a water-soluble phenol resin, polyvinyl alcohol, a silane compound and, if necessary, a solvent. 2. A casting composition comprising a water-soluble phenol resin, polyvinyl alcohol, a silane compound, a liquid organic acid ester-based curing agent, a granular refractory aggregate and, if necessary, a solvent. 3. A solution of a binder composition containing a water-soluble phenolic resin, polyvinyl alcohol, a silane compound and a solvent, a liquid organic acid ester-based curing agent, and a particulate refractory aggregate are mixed. A method for producing a casting mold, wherein the mold is housed in a mold frame, molded and cured.