JPS6012248A - Mold release agent composition for casting mold - Google Patents

Abstract

PURPOSE:To provide a mold release agent compsn. for a casting mold which has no tack after drying of the coated film and maintains the mold parting characteristic for long by adding a specifically composed silicone resin and inorg. powder to an org. solvent. CONSTITUTION:A mold release agent for a casting mold is prepd. by mixing 50-94pts.wt. gasoline, toluene, petroleum benzine, etc. as an org. solvent for dissolving the silicon resin with 5-30pts.wt. inorg. powder such as graphite powder, Al powder, alumina powder, silica powder, etc. and 1-20pts.wt. a silicone resin consisting of silicone oil and silicone resin varnish at 9:1-1:9 ratio. The silicone resin varnish to be used in this case is preferably methyl silicone varnish of a copolymer consisting of the structural units of SiO2, CH3SiO3/2, (CH3)2SiO, (CH3)3SiO1/2 and phenyl methyl silicone varnish which is a copolymer consisting of the structural units of CH3SiO3/2, (CH3)2SiO, C6H5SiO3/2, (C6H5)(CH3)SiO (C6H5)2SiO.

Description

[Detailed description of the invention] The present invention relates to the use of molding sand and arm frames such as wooden molds during mold manufacturing.

Furthermore, the present invention provides a mold release agent for molds that is free from stickiness after the coating film dries and has excellent mold release durability.

Conventionally, compositions based on water-repellent substances such as oils and fats, paraffin wax, and silicone have been used as mold release agents for molds. In particular, silicone mold release agents are widely used because of their excellent mold release effects. However, silicone-based WaS agents generally contain silicone oil, and although they have excellent mold release properties, they tend to stick to fingers when transporting the mold after application, resulting in peeling, and the number of applications between application and re-use is small. There were some problems with durability.

To solve this problem, Japanese Patent Application Laid-Open No. 52-17525.175
Publication No. 24 provides a mold release agent with excellent mold release persistence using curable silicone, but the silicone content in the composition is high (it is expensive and the silicone content on the frame surface is large It is uneconomical unless an organic metal salt or acid is added to cause crosslinking.

As a result of various studies in order to improve the drawbacks of such silicone-based mold release agents, the present inventor used a mixture of silicone oil and silicone resin varnish instead of silicone resin.
Furthermore, by simultaneously adding an appropriate amount of inorganic powder to this, we have discovered a mold release agent for molds that has an excellent mold release effect and is resistant to peeling (long-lasting mold release), resulting in the present invention.

That is, the present invention uses 5 to 30 parts by weight of inorganic powder and 5 parts by weight of organic solvent.
0 to 94 parts by weight and 1 to 20 parts by weight of a silicone resin in which the weight ratio of silicone oil and silicone resin varnish is 9:1 to 1:9, and is non-sticky (mold release for casting with long mold release durability). It is intended to provide an agent for

The silicone resin varnish in the present invention is 5in2.01 (3SiO%) having a structure like Narita.

(OH) 810. (OH3)38103. Methyl silicone face or 0H5Si, which is a copolymer consisting of structural units of
O5A* (OH3)2SiO1O, 5H5siO%,
C06H5) (OH3)810・(06H5)2S
Phenylmethyl silicone varnish, which is a copolymer consisting of iO structural units, is preferred.

As the silicone oil in the present invention, for example, modified silicone oils such as dinotyl silicone oil, methylphenyl silicone oil, diethyl silicone oil, methylhydrodiene polysiloxane and α-methylstyrene modified silicone oil can be mentioned.

In the present invention, the weight ratio of silicone oil and silicone resin varnish as silicone resin is 9:1 to 1:
It is 9. If the silicone oil is more than this ratio, the stickiness improvement effect will be small, and if it is less, the mold release effect will be insufficient. Further, the amount of silicone resin blended in the composition of the present invention is practically 1 to 20 parts by weight, preferably 2 parts by weight.
~10! This is the ffi section. If the amount is less than this, the mold release durability will be poor, and if it is more than this, silicone will adhere to the mold after the mold is removed from the flask and contaminate the surface of the mold.

The inorganic powder in the present invention has the function of further enhancing the mold release effect of the silicone resin. In other words, silicone-based mold binders that do not contain inorganic powder cannot satisfy the properties of stickiness, durability, and release properties of the coating film at the same time;
This becomes possible by including inorganic powder. Furthermore, it is also possible to prevent uneven coating by using colored inorganic powder. As the inorganic powder, it is preferable to use a chemically inert powder that does not have a particularly negative effect on the casting even if it adheres to the mold to some extent when the mold is released from the flask.For example,
Examples include graphite, aluminum powder, stone pollen, silica powder, alumina powder, talcum powder, and inorganic pigments such as zircon flour and red iron. The amount of inorganic powder in the composition of the present invention is 5 to 5.
The amount is 30 parts by weight, which is 2 to 10 times the weight of the silicone resin in the composition. When the amount is less than this, the mold release effect is small, and when it is more than this, the coating film becomes extremely brittle.

The organic solvent used in the present invention can be arbitrarily selected depending on the environmental conditions and usage conditions (drying rate, etc.) as long as it dissolves the silicone resin. For example, gasoline, petroleum benzine, mineral spirits, toluene,
Examples include xylene, trichloroethylene, carbon tetrachloride, methylene chloride, and acetone.

In addition to the above-mentioned essential components, the composition of the present invention may optionally contain a titanium tropic agent such as Aerosil, an antifoaming agent, a thermoplastic polymer such as paraffin wax or polystyrene, and the like.

The present invention will be further explained in detail with reference to Examples below.

Examples 1 to 4 The pull-out load and stickiness of the mold release agent composition for molds of the present invention using methyl silicone varnish as the silicone resin varnish were measured. The results are shown in Table-1. In addition, using silicone resin [Reference example 1 to 1] where only silicone oil or silicone varnish is used and when no inorganic powder is used.
3.

a] Dimethyl silicone oil, 300008b] Apply a mold release agent to the two molds and embed them in the mold,
After curing, use a tensile tester to measure the pullout load and convert it to per unit area.

C) Stickiness Apply a mold release agent onto a glass plate and evaluate stickiness by touching it with your finger. (Good) 5-→1 (Bad)゛.

Examples 5 to 8 The pull-out load and stickiness of the mold release agent composition of the present invention using phenylmethyl silicone varnish as the silicone resin varnish were measured. The results are shown in Table-2. At the same time, cases in which only silicone oil or silicone varnish was used as the silicone resin and cases in which no inorganic powder was used were shown as Reference Examples 4 to 6.

Examples 9 to 11 The persistence of the am effect in the M-type agent composition for molds of the present invention using methyl silicone varnish as the silicone resin varnish was examined. That is, after applying a mold release agent to the wooden mold, embedding and removing the wooden mold were repeated a predetermined number of times. The pullout load was measured using this wooden pattern. The results are shown in Table-3. Note that reference example 7 is one in which no silicone varnish is blended.

Table-5

Claims (1)

[Scope of Claims] t 5 to 60 parts by weight of inorganic powder, 50 to 94 parts by weight of organic wetting agent, and 1 to 20 parts by weight of silicone resin in which the weight ratio of silicone oil to silicone resin varnish is 9=1 to 1:9.
A mold release agent composition for molds, comprising parts by weight. 2 Silicone resin varnish is 8i0□, 0H313io
stomach. (OHx)28i0. The mold release agent composition for molds according to claim 1, which is a methyl silicone varnish or a certain phenylmethyl silicone varnish which is a copolymer consisting of structural units of (OH,)3Si03A.