CS248221B1 - Production method of degreased mouldings and plastics rid of separator - Google Patents

Abstract

The invention relates to a process for the production of degreased molded plastic parts separator with special regard to moldings made of hard integral polyurethane foams, by a process comprising applying a separator to the functional surface of the mold, its drying, applying product layer unfinished) polyvinyl acetate acetate methanolysis saponification number 150 to 300 per dry layer of blister, its drying, injection a polymer or a mixture of component forming components the polymer into the mold, removing the molding from mold and its rinse from product unfinished) all alcohol PVAc and separator water.

Description

The present invention is concerned with a method of degreasing and removing a separator from plastic moldings, particularly hard integral foam moldings.

One of the basic operations that precedes the surface treatment of products is the removal of the treated product from grease, which is particularly contaminated in mechanical production. In the case of molded articles, there is also the need to remove the molding of the separator, which is ejected by the mold, and which may have different properties than the grease with which the molding is contaminated. To get rid of the separator molding and grease is an essential condition for it to be dyed and painted. For this purpose, a number of complicated procedures have been developed: degreasing in organic solvents, in solutions of alkaline preparations, emulsion degreasing, electrolytic degreasing, ultrasonic degreasing and others.

A special case arises when we want to degrease and get rid of separator shaped moldings made of plastics, such as hard integral polyurethane foams. Such moldings often have broken shapes, a vitreous surface layer in which the separator is pressed. If the separator is a low-molecular-weight polymer, for example based on silicones, it causes a consequent insufficient adhesion of the coatings, so that the surface of the parts must, in addition to degreasing, also be sanded and roughened.

Degreasing and removal of the separator with organic solvents is not desirable for health and safety reasons. When lubricated in organic solvent vapors, higher temperatures can cause considerable deformation of the compact. There is also a risk of deformation when degreasing and removing the separator in alkaline solutions at temperatures of about 100 ° C. Higher temperatures are used because efficiency is lower at lower temperatures.

Grinding and roughening of rigid integral foam moldings of polyurethane foams often disrupt the shell-like vitreous layer and the freon in the deeper layers will begin to expand and eventually disrupt the finishes. Another drawback of mechanical roughening is that the abrasive separator is partially pressed into the surface layer.

The described drawbacks address the process for producing degreased plastic moldings free of separator by a process comprising depositing a separator on a functional surface of a mold, injecting a polymer or blend of molding polymer components and removing the molded part by applying a layer of incomplete alcoholysis product to the dried separator layer. polyvinyl acetate (PVAc) having a saponification number of 150 to 300 and, after removal of the molding from the mold, rinsing with water.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fine PVAc film on the molded part, in which the alcoholic analysis does not take place to the end and which therefore has particular properties. It is soluble in water, such as polyvinyl alcohol, and partially soluble in organic solvents such as polyvinyl acetate. It is only on this film that the separator from the functional mold walls and greasy debris such as petrolatum and oils remain, and all of the undesirable impurities can be easily and quickly removed with the film from the molding.

Advantages of the proposed solution:

1. Quick, easy degreasing and complete removal of the separator from the compact without the use of organic solvents or alkaline degreasing agents.

2. The possibility of successfully replacing cost-intensive coatings that do not require long drying and curing times.

3. Moldings in polyurethane do not need to be roughened for higher subsequent paint adhesion than necessary to date.

4. Health and hygiene advantages are not negligible.

5. Self-cleaning of mold walls from separator deposit.

The solution illustrates, but does not limit, the following example:

Example 1 and id

A metal heated mold sprayed with a silicone release agent (Atmosil) is sprayed once more with an aqueous-alcoholic solution of the unfinished polyvinyl acetate alcohol saponification product having a saponification number of 150 and the mold is closed after drying. A mixture of isocyanate and polyol with a foaming agent is injected into the mold. After the reaction is completed and the molded part is removed and deburred, it is simultaneously degreased and removed from my separator by washing with water at 40 ° C.

Claims (1)

SUBJECT Process for producing degreased molded parts of plastic free of separator by a process comprising applying a separator to the functional surface of a mold, injecting a polymer or a mixture of the polymer-forming components into the mold and removing the molded part BACKGROUND OF THE INVENTION characterized in that a layer of unfinished polyvinyl acetate alcohol saponification product having a saponification number of 150 to 300 is applied to the dried separator layer and rinsed with water after removal of the compact from the mold.