JPS61106209A - Composition of parting agent for forming resin - Google Patents

Abstract

PURPOSE:To obtain film making parting agent capable of permitting to take out a formed product simply without affecting on the surface of the molded product badly by a method wherein a film making composition, in which water- soluble alkaline alginate, water-soluble alkaline polyphosphate, water-glass, alcohol and water are blended in a specified ratio, is employed. CONSTITUTION:Water solution, consisting of 1-10% of water-soluble alkaline alginate, 0.05-1% of water-soluble alkaline polyphosphate, 0.1-10% of water- glass, 5-15% of alcohol and 64-94% of water, is employed. Various effects such as the formation of calcium alginate due to reaction between the alkaline alginate and calcium in plaster, regulation of forming speed of calcium alginate due to the alkaline polyphosphate, the reinforcing of parting film as well as increasing of parting effect due to water-glass, the promotion of rate of volatilization of solvent as well as anti-corrosive effect due to the alcohol or the like, are developed in a very good balance and a rigid parting film is formed while the parting agent will never be reacted or dissolved by casting resin, or monomer or diluting agent in putty resin and resin is cured, furthermore, the agent can stand sufficiently against heat during curing process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold release agent for resin molding, and its purpose is to coat and dry the surface of a mold to form a tough film, which will not be attacked by the resin used and will remain stable during the resin curing. Film-forming properties that can withstand heat generation or heating temperatures, are not affected by heating media, have a sufficient release effect between the mold and the molded product after the resin has hardened, and can be easily removed from the molded product without adversely affecting the surface of the molded product. It is difficult to obtain a mold release agent.

Conventionally, as this type of mold release agent, various water-soluble polymer compounds such as 1, fluorine, CMC, methyl cellulose, sodium alginate, polyvinyl alcohol and other aqueous solutions and organic solvent-soluble polymer compounds such as cellulose acetate, vinyl acetate, silicone varnish, etc. have been used. Paraffin, microcrystalline wax, and other emulsion-type polymer compounds, such as vinyl acetate, styrene, acrylic acid, etc. alone or copolymers, or mixtures thereof, and various waxes are applied to the mold and dried. Either a film was formed using a mold and the resulting film was used as a mold release film, or a wax was heated and melted and impregnated or applied onto a mold to form a coagulated layer on the surface of the mold and used as a mold release layer.

However, some mold materials are porous, and if the viscosity of the mold release agent is low or the solvent evaporates slowly, the mold release agent will be absorbed into the mold and a thin film of mold release agent will form on the surface of the mold. is not formed, or even if a good film is formed.

The film may become soft and deformed due to attack by the molded product raw material or its diluent, heat generation due to heating or polymerization during the molding process, or damage to type 1 film caused by water in the mold material. If the whitening is more severe, problems such as whitening of the surface of the molded product and poor curing may occur, and the molded product may adhere or even stick to the mold, which can lead to damage to the mold as well as damage to the molded product. Therefore, the selection of a mold release agent depending on the molding conditions is one of the conditions for obtaining a better molded product, and selection requires experience and is a very troublesome task.

Therefore, as a result of intensive research, the composition of the present invention was obtained.

Namely, water-soluble alkali alginate salt 1-10%, water-soluble alkali polyphosphate salt 0.05-1%, water glass 0.1-1%.
0%, A/L/Near/L15-15%, Water 64-94
It has been found that an aqueous solution having a viscosity of 50 to 1 oooocps consisting of 50% to 100ocps is most suitable as a mold release agent, particularly for porous molds, especially plaster molds, leading to the present invention. Namely, formation of calcium alginate by reaction with calcium in gypsum by alginate alginate, adjustment of the formation rate of calcium alginate by polyphosphate alkali salt, reinforcement of mold release film and increase of mold release effect by water glass, and alcohol. The various effects such as accelerating the volatilization rate of the solvent and preservative effect are synergized in an extremely well-balanced manner, resulting in a strong mold release film.

It is formed, does not react or dissolve with the monomer or diluent in the casting resin or putty resin, can cure the resin, and does not absorb light from heating or heat generation during the resin curing process. It is something that can last for a long time.

(The water-soluble alginate alkali salts to be used include sodium, potassium, ammonium, and triethanolamine salts, among which sodium salts are the best. Examples of the polyphosphoric acid alkali salts include toguchi phosphoric acid, trimetaphosphoric acid, tetrametaphosphoric acid, etc. It is a single substance or a mixture of sodium, potassium, and ammonium salts, and is not particularly pure and is commercially available, such as commonly known as sodium polyphosphate.Water glass is a concentrated aqueous solution of alkali silicate gallus. Diatom 4n=2~4, specific gravity 30~
One in the range of 70°B e / is used. Methyl, ethyl, isopropyl, etc. can be used as the alcohol, but ethyl alcohol is most suitable in consideration of toxicity and volatility. In addition, it is also possible to add small amounts of known preservatives, dyes, alcohol-soluble oils, and the like.

Although the mold release agents of the present invention are particularly useful in molding resins using plaster molds, they can also be used in other types of molds, such as wooden molds and metal molds. When using a porous mold, you can change the molecular weight or concentration of the alginate alkali salt depending on the degree of porous mold, but there is no strict limit to this, and if the coating film is thin, it may be necessary to apply a thick coating. Or you can reapply.

The types of resins used include styrene-modified polyester resin, allyl-modified polyester resin, epoxy resin,
Phenol resins, urethane resins, acrylic resins, etc., and putty-like resins made by mixing suitable fillers or glass fibers with these resins are used by casting or laminating methods, but especially The type of resin and molding method are not limited.

Usually a mold is made of plaster, whether it is male or female.
Apply the mold release agent of the present invention to the area in contact with the resin or the excess area and dry it to form a thin film for treatment, and then inject, fill, or dip the resin as described in 1. If the molded product is laminated with glass fiber, etc. according to the requirements, and then removed from the plaster mold using an appropriate method after curing, a molded product with a glossy surface, that is, the same surface state as that of the mold release agent, can be obtained. It will be done.

Example 1. Sodium alginate 5%, polyphosphoric acid sodium yo
, s%, water glass 3%, ethyl alcohol 10%, water 8
Make a 1.5% uniform aqueous solution, apply it to the inner surface of a plaster split mold with a brush, dry it, and cast a polyester resin (Evolac GloA manufactured by Nippon Shokubai) containing a curing agent and an accelerator.
After waiting for the resin to harden, a light impact was applied to the plaster split mold to separate the mold. The molded product and the plaster mold were not damaged in any way, and a glossy molded product was obtained. The plaster mold was then reapplied with this mold release agent and could be reused.

Example 2. Sodium alginate 6%, Sodium tripolyphosphate 0.5%, Water glass 3%, Isopropyl alcohol 10%
%, alcohol-soluble Noricon oil (Shin-Etsu Chemical KF-
56) 0.1%, Fnorfucrene 0.05%, water 8
Make a 0.35% aqueous solution colored pale pink-pink, apply it to the surface of a plaster mold for acoustic horn molding, repeat drying twice, create a thick coating film, and apply epoxy resin (Shell Kagaku Epo/820) on top of it. 80 parts, curing agent 15 parts, thixotropic agent (
While applying 5 parts of Carplex (Shionogi & Co., Ltd.), glass mats and fibers were laminated to a thickness of about 10 marks, and after waiting for the resin to harden, the molded horn was extracted from the stone mold while applying a slight impact. The surface that had been in contact with the plaster had a glossy finish and could be immediately applied with a finishing coat.

Example 3. An acrylic resin denture was manufactured according to a conventional method using a mold release agent having the same composition as in Example 1 as a separation agent for manufacturing a dental denture. That is, a wax denture is embedded in a flask with plaster, a plaster mold is made, the wax is washed away, a mold release agent is applied, it is dried, and a putty-like mixture of floor resin made of polymethyl methacrylate and its monomer is filled. A post-heat polymerization operation was performed. After the mold had cooled sufficiently, the plaster was cracked and the denture was removed, but its surface was shiny and did not require much polishing.

Claims (1)

[Claims] Water-soluble alkali alginate salt 1-10% (same as below weight%), water-soluble alkali polyphosphate salt 0.05-1%, water glass 0.1-10%, alcohol 5-15%, water 64-10%
A film-forming mold release agent composition for resin molding consisting of 94%.