JP3128603B2 - Release agent for green molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release agent which is applied to a mold (model) when a green mold is formed.

[0002]

2. Description of the Related Art Green molds are still the mainstream of molds because they can be poured immediately after molding, the mold sand can be easily recycled, and the mold cost is low.

Conventionally, a molding die used for molding a green mold is liable to adhere to molding sand for green molding, and it is difficult to obtain a clean green mold. The reason is that while green sand (mold) is made of aggregate, clay, water and other additives, the mold is usually made of iron (for example, cast iron) whose contact angle with water is substantially 0 °. Because there is.

[0004] For this reason, conventionally, plating (usually electroplating) of nickel, chromium, or the like having a larger contact angle with water than iron has been applied to the surface of the mold.

[0005]

However, in the case of a green mold, a part of the mold is often modified (particularly in a trial production stage) because of the simplicity of the mold. On this occasion,
It had to be plated again, which was troublesome. Furthermore, depending on the composition of the green sand, that is, the type of the binder and the additive, there is a possibility that the effect of preventing the green sand from being sufficiently adhered may not be exhibited.

[0006] In view of the above, the present invention provides a green mold that allows a beautiful green mold to be formed simply by coating and using a metal mold without applying a metal plating having a large contact angle to the metal mold. An object of the present invention is to provide a mold release agent.

Another object of the present invention is to provide a mold release agent for green molding capable of sufficiently exerting an action of preventing the adhesion of green sand.

[0008]

The mold release agent for green molding according to the present invention solves the above problems by the following constitution.

[0009] A mold release agent for green mold making which is used by applying it to a model mold when forming a green mold, wherein polymetallocarbosilane as a mold release component is dissolved in a non-polar organic solvent. It is characterized by.

[0010]

[Detailed Description of Means] Next, each component of the above means will be described in detail.

(1) In the mold release agent for green molding according to the present invention, polymetallocarbosilane is dissolved in a non-polar organic solvent as a mold release component.

(2) The polymetallocarbosilane used herein comprises (A) a carbosilane binding unit described below and at least one kind of a (B) metalloxane binding unit described below, (In the formula, R ¹ and R ² may be the same or different and each independently represent an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a hydrogen atom.) (B): (-MO-) ( In the formula, M represents at least one element selected from the group consisting of Ti, Zr, Mo, and Cr, and in some cases, at least a part of each of the elements is an alkoxyl group having 1 to 4 carbon atoms or a phenyl group as a side chain group. And (B) a polymer in which each of the bonding units is randomly bonded in the main chain skeleton, and / or at least a part of the silicon atoms in the bonding unit of (A) is Each of the metal elements of the bonding unit (B) is bonded via an oxygen atom, whereby the polycarbosilane moiety obtained by the chain of the bonding unit (A) is bonded to the bonding unit of (B) via oxygen. It is a crosslinked polymer.

The total number of the bonding units of the above (A) versus the above (B)
Is preferably in the range of 1: 1 to 10: 1. The number average molecular weight of the polymetallocarbosilane is preferably from 400 to 50,000.

(3) Further, as the non-polar organic solvent,
Toluene, xylene, hexane, cyclohexane, industrial gasoline, petroleum benzene, paint thinner, methanol, ethanol and the like can be used. A polar organic solvent cannot dissolve polymetallocarbosilane.

(4) The above-mentioned polymetallocarbosilane is used after being diluted with the above-mentioned non-polar organic solvent to an appropriate concentration, usually 3 to 30% by weight (preferably 5 to 15% by weight). If it is less than 3%, it is difficult to impart a mold releasing action (water repellency to which green sand does not adhere) to the mold, and if it exceeds 30 wt%, the mold releasing action (water repellency imparting effect) does not further increase and the viscosity is high. There is a possibility that the workability of application to the mold may be adversely affected due to the excessive application.

At this time, usually, a release agent can be obtained simply by dissolving the polymetallocarbosilane in a non-polar organic solvent, but a surfactant, an inorganic filler or the like may be added as appropriate. it can.

(5) The release agent thus prepared is used by applying it to a mold before molding. At the time of this application, the green sand to be reused is usually in a heated state of about 40 ° C. due to the influence of the molten metal. Therefore, it is preferable to heat the mold to about 40 ° C. This is for preventing dew condensation on the mold surface.

The coating method is optional, such as spraying, brushing, dip coating, etc., but spray coating is desirable from the viewpoint of workability. The coating thickness is 10 when dry.
To 100 μm (preferably 40 to 60 μm).

Further, after the application, it is desirable to heat and dry mainly in order to accelerate the evaporation of the solvent, but if there is time, natural drying may be used.

The mold having the release film thus formed can be used repeatedly for green molding. By the way, about the thing which spray-coated 3 times of the toluene solution of 10% by weight of polytitanocarbosilane, green molding was performed 300 times, but adhesion of green sand to the mold was not observed.

[0021]

The release agent for green molding according to the present invention is obtained by dissolving polymetallocarbosilane in a non-polar organic solvent as described above, and is applied to a mold during green molding. By simply doing so, it is possible to impart an effect of preventing green mold sand from adhering to the mold surface as supported by the test examples described below.

Therefore, it is possible to form a beautiful green mold simply by applying a metal plating having a large contact angle to the mold without using a metal plating.

Further, as compared with the case where conventional nickel plating is applied, the contact angle is remarkably high, and extremely high water repellency can be imparted to the mold surface. That is, regardless of the composition of the green sand, that is, the type of the binder and the additive, the effect of preventing the green sand from adhering can be sufficiently exerted.

In JP-A-63-12672, a coating composition (release agent) containing the polymetallocarbosilane used in the present invention as an essential component and applied to a substrate such as iron is used. It has been disclosed.

However, the known release agent is different from the release agent of the present invention and does not affect the inventive step of the present invention.

The mold release agent of the present invention is a mold release agent for green molding, and is intended to have releasability from green molding sand which contains a large amount of water and is at most about 40 ° C. at the time of molding. On the other hand, the above-mentioned known mold release agent has a high
(° C. or higher) for the purpose of releasability from a metal melt such as aluminum or a glass melt, and the two purposes are completely different.

[0027] In the present invention, among the components responsible for the releasing action, the present invention is "polymetallocarbosilane", while the known releasing agent is mainly "boron nitride powder" (see the lower page of the above-mentioned page 2). Left column, first row). Polymetallocarbosilane is only suggested to be mainly responsible for the adhesion to the substrate (fourth column, lower left column, page 2 of the publication),
There is no suggestion in the above publication that polymetallocarbosilane plays a role of releasing.

[0028]

Test Examples Hereinafter, a water repellency test, which is an indirect test, performed to confirm the effects of the present invention will be described.

(1) A test piece prepared by treating a 70 × 70 × 5 mmt iron plate or cast iron (FC) plate with a release agent by the following method was placed horizontally as shown in FIG. A water drop 2 was dropped on the heated test piece 1 maintained at 40 ° C., and the contact angle の immediately after the drop was measured, and a three-point average was obtained.

The release agent treatment is performed by applying a release agent (10 wt% polytitanocarbosilane in toluene solution) three times by brushing, and then naturally drying for 60 minutes → 200 ° C. × 30 minutes → 25
The drying was performed under the conditions of 0 ° C. × 15 minutes (dry film thickness: about 5
0 μm). As the polytitanocarbosilane, "Tyrannocoat VN110" manufactured by Ube Industries, Ltd. was used.

The results were as follows: iron plate: 83.7 ° (normal temperature), 74.7 ° (40 ° C.), FC plate: 84.3 °
(Normal temperature) and 74.7 ° (40 ° C.). At normal temperature, the contact angles of iron and nichrome with water are 0 ° and 6.5 °, respectively (see “Chemical Handbook Basic Edition II”).
Maruzen, p. 541).

It can be seen that those treated with the release agent of the present invention exhibit much better water repellency than the nickel plating treatment.

[Brief description of the drawings]

FIG. 1 is a model sectional view of a water repellency test of the present invention.

[Explanation of symbols]

 1 Test piece 3 Water drop Θ Contact angle

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiro Nakamura 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Tsujihiko Yasuda 230 Okitacho, Nakamura-ku, Nagoya City, Aichi Prefecture Chubu Sukegawa Kogyo Co., Ltd. Inside the company (72) Inventor Akiyoshi Sanano 230 Okita-cho, Nakamura-ku, Nagoya-shi, Aichi Prefecture Inside Chubu Sukegawa Kogyo Co., Ltd. (56) References JP-A-63-12672 (JP, A) JP-A-63-260655 (JP, A) JP-A-64-31546 (JP, A) JP-A-6-218489 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22C 3/00

Claims (3)

(57) [Claims] 1. A mold release agent used by applying to a mold when molding a green mold, wherein polymetallocarbosilane as a mold release component is dissolved in a non-polar organic solvent. Release agent for green molding. 2. The mold release agent according to claim 1, wherein the concentration of the polymetallocarbosilane is 3 to 30% by weight. 3. The mold release agent according to claim 1, wherein the polymetallocarbosilane is the polytitanocarbosilane.