DE682347C - Prevention of skin formation during the usual solidification of a rubber milk foam produced in a known manner on molds - Google Patents

Description

Prevention of skin formation during the usual solidification of a known Way produced rubber milk foam on molds In the production of porous or spongy articles made of rubber milk, it is often desirable at least to avoid the formation of a superficial skin in certain places. As such Objects are e.g. B. to be named toys such as dolls, balls, etc., toilet sponges, Filters, cushioning materials and the like, in other words, items in which a undisturbed absorption or circulation of a gas or liquid the whole subject is an essential requirement.

If the subject is not cut out of a large block sore, the sponge structure had to be exposed by initially skin formed in the molding process has been mechanically removed or ablated, z. B. by suffering or by cutting off or by rubbing the surface. In any case, this is an expensive, time-consuming and therefore unsatisfactory measure.

It has now been found that in the production of 5 sponge rubber articles from rubber milk, d. H. by converting said dispersion into a foam and by settling-un, allowing the foam to solidify in a container, so that it is given a certain shape, the formation of an outer skin is substantially restricted and, if necessary, can be eliminated entirely, at least over a portion the total surface of the object (i.e. over the whole surface or over one or more specific parts of the surface, as required) when on a coating of one or more substances is applied to the surface of the mold, which reduce the surface tension of the dispersion and at the same time no coagulating or gelatinizing influence, rather a stabilizing one - Influence the dispersion.

It is understood that this invention is not limited to any particular one The way in which the foam is produced from the dispersion is still limited to a specific one Way of bringing about the transformation of the dispersion into a solid structure, or any other special consequence of the individual measures. Manifold materials of the most varied chemical structure are known to reduce the surface tension of a Watery skin schukdispersion cause, and many of them have at the same time have a stabilizing influence on the dispersion, namely inasmuch as they promote coagulation or delay or prevent setting.

Examples of such substances are the sodium salt of Oleyloxäthylsulfonsäure Ct7 H33 C O O C H2 C H2 S 03 Na (Igepon A), the sodium salt of oleylaminoethyl sulfonic acid C17H33 CO NH. CH2.

C H2 5 O Na (Igepon T), the sodium salt of di-isopropyluaphthalene-ß-sulfonic acid and their homologues (Nekal B X), all of which are substances from the 1. G. Farbenindustrie be put on the market.

Another example of such substances is the sulfuric acid ester of the cetyl alcohol, which Imperial Chemical Industries Ltd. under the name of Lissapol A puts on the market.

The nature of the matter of which the form is made is of a certain nature Meaning.

The desired effect is achieved both on a non-porous, e.g. B. metallic, like on a porous surface, e.g. B. one made of wood, received, although found wound that the effect is more pronounced and lighter on a non-porous surface can be achieved especially on aluminum.

In practicing the invention, the foam can be a dispersion of Rubber rise through a mass of fibers when it is produced by negative pressure and penetrate them, which is housed within a mold. On the surface The form is a solution of the above-mentioned sodium salts or esters, which reduce the surface tension of the dispersion and stabilize it at the same time can, in a thin layer. At least some of them are left to dry. On it will brought the required amount of a suitably composed rubber milk into the mold and e1ny pressure reduction brought about. After the dispersion has foamed and has been hardened, the object can be removed from the mold will. He shows no skin formation on the parts of the surface where the above-mentioned Substance was brought to the mold surface. When the rubber milk foam before or has collapsed during the hardening process, becomes a skin-free rubber-bonded one Obtain fiber mass.

Since the coagulated foam does not adhere to the parts of the mold wall, which are treated in the manner described, it may turn out to be necessary to provide a support for the coagulated foam to prevent possible collapse to prevent. For this purpose, a very loose network (a fishing net or Strands of twine or wire) are attached to the shaped object pull through in certain places and allow its handling during molding. The strands can be pulled out afterwards.

Claims (2)

PATENT CLAIMS: I. Prevention of skin formation in the ulcer Solidifying a rubber milk foam produced in a known manner on molds, characterized in that the surface parts of the molds which are to be kept skin-free be coated with a substance that reduces the surface tension of the foamed rubber dispersion reduces and not a coagulating or gelatinizing, rather an expedient one has a stabilizing effect on the rubber dispersion. 2. The method according to claim I, characterized in that on the A solution is brought into the mold which contains one or more substances from the the following group contains: sodium salt of oil eyloxäthylsulfonsäure, sodium salt of oleylaminoethylsulfonic acid, sodium salt of di-isopropylnaphthalene-ß-sulfonic acid and their homologues and sulfuric acid esters of cetyl alcohol.