JPH04305330A - Release agent for forming green molding - Google Patents

Abstract

PURPOSE:To provide the mold release agent for forming a green molding which can increase the stability of the green molding surface and eliminates the need for an operation to apply a surface stabilizer on the green molding after molding. CONSTITUTION:The mold release agent used to improve the release property and surface stability at the time of molding the green molding is a W/O type emulsion formed by dispersing a water phase into an oil phase of a hydrocarbon system using a surfactant as a dispersant and by dissolving a watersoluble greensand binder into this water phase.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold release agent for improving the releasability and surface stability of green molds when molding them.

[0002] In the following explanation, "part" and "part" indicating the compounding unit are used.
%" is in units of weight unless otherwise specified.

0003

[Prior art] The most primitive type of mold, the raw mold,
Compared to other thermosetting, self-curing, and gas-curing molds, molding productivity is better, the mold material is cheaper, and it can be used repeatedly, so it is still the mainstream mold. .

[0004] As a mold release agent for green mold making, a W/O emulsion in which an aqueous phase is dispersed in a hydrocarbon oil phase using a surfactant as a dispersant was developed by the same person as the present applicant. system has been proposed (Special Publication No. 63-296
(See Publication No. 25).

However, in the case of the above-mentioned type of mold release agent, the stability of the surface of the green mold (cavity surface) that has been released from the mold is not always sufficient. If the surface of the green mold is not sufficiently stable, the hot water pressure during pouring will cause the green sand to collapse on the cavity surface, resulting in poor shape of the casting.

[0006] This unstable phenomenon of the surface of the green mold is caused by (1) drying of the surface of the green mold over time, or (2) a decrease in the caking property of green sand, which is a releasing agent, due to excessive application of a mold release agent. Conceivable.

For this reason, the surface of the green mold after molding (
This was dealt with by applying a surface stabilizer containing a green sand binder dissolved in it, mainly on the cavity surface.

[0008]

[Problems to be Solved by the Invention] However, this requires a surface stabilizer coating operation, which is undesirable because the productivity of the green mold decreases as a whole.

In view of the above, the present invention provides a mold release agent for green mold making that can increase the stability of the green mold surface and eliminates the need for applying a surface stabilizer to the green mold after molding. The purpose is to provide.

0010

[Means for Solving the Problems] The mold release agent for green molding of the present invention solves the above problems by the following constitution.

[0011] A mold release agent for improving the mold releasability and surface stability of the green mold when molding the green mold, the mold release agent comprising:
In a green mold molding release agent which is a W/O type emulsion in which an aqueous phase is dispersed in a hydrocarbon oil phase using a surfactant as a dispersant, a green sand binder soluble in the aqueous phase is used. It is characterized by dissolving.

0012

[Detailed explanation of means]

A. The mold release agent for green molding of the present invention is made by dispersing an aqueous phase in a hydrocarbon oil phase using a surfactant as a dispersant.
/O type emulsion is a prerequisite.

(1) The above-mentioned surfactant may be nonionic, anionic, cationic, or amphoteric, but the following nonionic and anionic surfactants are particularly preferred.

■Nonionic surfactant: alkyl polyoxyethylene ether, alkyl carbonyloxy polyoxyethylene, p-alkyl phenyl polyoxyethylene ether, N N-di(polyoxyethylene) alkanamide, fatty acid polyhydric alcohol ester , fatty acid polyhydric alcohol polyoxyethylene, fatty acid sucrose ester, and ethylene oxide adduct of castor oil.

■Anionic surfactant: higher fatty acid alkali salt (soap), sodium alkyl sulfate, di-sulfuric acid
Sodium alkyl, sodium alkylbenzenesulfonate, sodium α-olefin sulfonate, sodium N-acylamino acid, sodium alkylnaphthalate, sodium N-(2-sulfo)ethyl-N-methylalkanamide, 2-sulfosuccinic acid dialkylamide.

The composition ratio of the surfactant is the total amount of water and oil: 1
00 parts, 1 to 30 parts (preferably 2 to 20 parts)
shall be. If it is less than 1 part, it will be difficult to prepare a W/O emulsion, and if it exceeds 30 parts, the effect will not increase commensurate with the amount.

(2) As the above-mentioned hydrocarbon-based oil, a petroleum-based oil having a flash point of 55° C. or higher is usually preferable from the viewpoint of flame retardation of the mold release agent. Specific examples include lubricating oils such as gear oil, machine oil, bearing oil, and turbine oil, as well as kerosene and light oil. These can be used alone or in combination.

(3) The above composition ratio of oil and water is oil/water=
92/8~15/85 (preferably 88/12~25/
75). If the water content is less than 8%, the release agent will have a flash point, and if the water content exceeds 65%, it will be difficult to prepare a stable W/O emulsion.

B. A characteristic feature of the present invention is that the water phase contains a water-soluble green sand binder.

[0020] As the water-soluble green sand binder, water-soluble synthetic polymer materials such as carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA), animal materials such as gelatin and glue, agar, starch, etc. Vegetable materials such as sodium alginate, mineral materials such as bentonite, etc. can be used alone or in combination.

[0021] The blending amount of the water-soluble green sand binder, which also acts as an emulsion stabilizer, is 0 to 100 parts of water.
．． 01 to 50 parts (preferably 0.1 to 40 parts). If it is less than 0.01 part, it is difficult to obtain the effect of the present invention (surface stability of green mold), and if it exceeds 50 parts, it is difficult to adjust the W/O emulsion.

As a release aid, higher fatty acids such as stearic acid, palmitic acid, and oleic acid having 8 to 20 carbon atoms;
It is also desirable to add ester/amide derivatives thereof from the viewpoint of increasing mold releasability. The blending amount of these mold release aids is 0 to 20% (preferably 0.5 to 10%).
).

C. The mold release agent of the present invention contains each of the above ingredients,
Mix and add at the same time and stir at high speed with a mixer to prepare.

D. The mold release agent prepared by the above method is used by applying it to a model etc. when molding a green mold. Applicable models are not limited to metal models (cast iron, copper alloys, aluminum alloys, steel, etc.), and may be arbitrary, such as plastic molds (epoxy resin, etc.), plaster molds, wooden molds, etc. Also,
The application method is usually spray application, but brush application,
Dip coating is optional.

Furthermore, the amount of the mold release agent applied is usually 1
00 to 500cc/m2. After coating, it may be allowed to dry naturally, but from the viewpoint of productivity, it is desirable to force dry it by heating, blowing air, or the like.

Next, using the model, molding is continuously performed by various molding methods such as squeeze, jolt, blowing, and sand slinger.

[0027]

[Actions and Effects of the Invention] The mold release agent for green molds of the present invention has the above-mentioned structure and exhibits the following actions and effects.

Since the mold release film formed on the model is a W/O type emulsion, the oil phase comes into contact with the model side and provides a good mold release effect. In addition, after releasing the mold, that is, after molding,
Through the water adhering to the green mold side (which is usually more polar than the model), the green sand binder contained in the water moves between the sand grains on the green mold surface, acts as a binder, and increases the stability of Further, unnecessary portions of the unpressed sand (other than the mold) can be easily removed due to its water-retaining properties (particularly in Example 2).

[0029] Therefore, unlike the conventional method, there is no need to apply a surface stabilizer to the surface of the green mold after it has been released, thereby increasing the productivity of the green mold.

[0030]

[Examples] Examples carried out to confirm the present invention will be explained below along with comparative examples.

[0031] A mixture having the formulation shown in Table 1 was stirred in a beaker using a tabletop mixer for Examples 1 and 2 and Comparative Example 1 (conditions: 8000 rpm x 10 min.); , Each mold release agent was prepared by manual stirring using a stirring bar.

Then, 1 cc of each mold release agent was poured onto the inner surface of the cast iron metal model 1 having the cross section shown in FIG. 1 so as to be uniformly coated (slightly overcoated). Immediately after that, moisture content 3.5
% green sand material 3 was put into the inner surface of the metal model 1, and the squeeze head 5 was used to perform squeeze modeling. The molding conditions were: green sand input amount: 80g, squeeze pressure: 10kgf/
cm2, molding height: approximately 13 mm. Tests were then conducted on the following items.

(1) Stainability (mold releasability): after molding,
The metal model was inverted and dropped vertically from a height of 10 cm, and the green mold was released from the metal model 1. At that time, the degree of adhesion of the green sand to the metal model 1 was visually determined.

(2) Surface hardness (surface stability): The green mold was placed on a concrete floor with the release side facing up. Then, after leaving it in an atmosphere of ■10℃ for 3 minutes, ■30
After being left in a hot air atmosphere at 0° C. for 1 minute, the surface hardness of each sample was measured using a hardness meter (manufactured by Shinto Kogyo Co., Ltd.). In addition, a 28g steel ball was placed 10cm in the center of the green mold that had been heat-treated as described in ① above.
The change in appearance was visually judged by dropping the product from a height of .

(3) Surface sand grain stability: After leaving the mold in an atmosphere at 10°C for 1 minute, a filter paper soaked in water is pressed against the release side surface of the green mold, and the sand grains adhering to the filter paper at that time are The presence or absence of this was visually determined.

The results of each test are shown in Table 2.

(1) First, in terms of mold releasability, each of the examples of the present invention is not inferior to each comparative example, and it can be seen that they have sufficient mold releasability.

(2) In terms of surface hardness, the examples of the present invention have higher surface hardness than Comparative Example 1 before heat treatment, and have a higher surface hardness than Comparative Example 1 as well as Comparative Example 2 after heat treatment. High surface hardness. In addition, in the steel ball drop test, the green molds of each example only showed depressions on the surface, and the green molds did not break as in the comparative example. Furthermore, regarding the adhesion of sand grains to the filter paper, almost no sand grains adhered to the filter paper in the examples. From these results, it can be seen that the mold release agent of the present invention increases the surface stability of the green mold.

[0039]

[Table 1]

*1) Fog Solvent manufactured by Nippon Oil Co., Ltd. *2) Cosmo Nutra 3 manufactured by Cosmo Oil Company
50*3) Pearl Glue Tengu manufactured by Sun Orient Kagaku Co., Ltd. *4) Gohsenol GH-17 manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.

[0041]

[Table 2]

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a squeeze molding method used when performing a mold releasability test and the like.

[Explanation of symbols]

1...metal model, 3... Raw sand, 5...Squeeze head,

Claims (2)

[Claims] Claim 1: A mold release agent for improving the mold releasability and surface stability of the green mold when molding the green mold, the mold release agent comprising a surfactant as a dispersant and a hydrocarbon A green mold mold release agent which is a W/O type emulsion in which an aqueous phase is dispersed in an oil phase of a system, characterized in that a water-soluble green sand binder is dissolved in the aqueous phase. Mold release agent for molding. 2. The mold release agent for green mold making according to claim 1, wherein the green sand binder is added to the aqueous phase in an amount of 0.01 to 40 wt%.
A mold release agent for green molding, which is characterized by its ability to dissolve.