MXPA97008240A - Process for recoating elastomer material - Google Patents

Abstract

The present invention relates to: Process for coating and protecting elastomers, in particular EP (D) M elastomerite polymers, by applying to the preceding elastomers a coating or coating consisting of at least one layer of optionally reinforced protective material A with one or more layers of reinforcement material B, characterized in that: the expanded material selected from (i) linear or branched polyethylenes, (ii) ethylene vinyl acetate copolymer having an acetate content of vinyl from 2 to 18%, ionomeric resins, branched propylenes and the relative mixtures, the material B essentially consists of a non-expanded material newly selected from among (i), (ii) and the relativ mixtures

Description

PROCESS FOR RECOATING ELASTOMERI MATERIAL Description of the invention The present invention relates to a process for coating elastomers, in particular ethylene propylene copolymers (EPM) and ethylene propylene diene terpolymers (EPDM) with a material that can be removed or removed with ease. It is well known that almost all elastomers (for example copolymers of EP (D) M, block copolymers, polybutadiene, rubbers or rubbers of styrene butadiene, rubbers or acrylic rubbers, rubbers or nitrile rubbers), are sticky substances. This creates considerable problems when the preceding elastomers have to be coated or coated with suitable protective materials to preserve them from degradation, for example for storage and transportation. In fact, due to its tackiness, the elastomers adhere to the coating or coating material with consequent problems for the consumer, which faces great difficulties in separating the coating material from the elastomer. A material has been found which overcomes this drawback, by virtue of being able to efficiently coat or coat elastomers but at the same time can be separated from them without difficulty. Accordingly, the present invention relates to a process for coating elastomers, in particular EP (D) M elastomeric polymers, by applying to the preceding elastomers a coating or coating consisting of at least one layer of protective material (material A) optionally reinforced with one or more layers of reinforcing material (material B), characterized in that: material A essentially consists of an expanded material selected from (i) linear or branched polyethylenes , (ii) ethylene vinyl acetate copolymer with a content of vinyl acetate of 2 to 18%, ionomer resins, branched propylenes and the relative mixtures. material B essentially consists of a non-expanded material newly selected from (i), (ii), and the relative mixtures. In a form of the embodiment, when it is not necessary for the coating or coating material to exhibit mechanical characteristics (when the bales do not have to stick together (adhere to one another) and are used with the wrapping), the layer (or layers) ) protective (s) of the elastomeric material simply consists of at least expanded material (A), preferably a single layer of expanded material. In another embodiment, when on the contrary (yes) it is required to separate the rubber or rubber bales from the protective material film, the coating material or coating has to pss the appropriate mechanical properties to facilitate the peeling operation (remove or remove the coating); in this case it will consist of at least one layer of expanded material (A) and at least one layer of unexpanded material (B), preferably a layer of unexpanded material (B) covered with two layers of expanded material (A). As mentioned above, polyethylenes belonging to the groups of LLDPE (linear low density polyethylenes), ULDPE (ultra low density polyethylenes) and VLDPE (high density polyethylene) can be used as material (A) or material (B). low density) . As is known, these are copolymers of ethylene and propylene, ethylene and butene, ethylene and hexane, ethylene and octene. EVA (vinyl acetate ethylene) copolymers having an ethylene content between 2 and 18% by weight, preferably 4 to 14%, and ionomer resins can also be used. The difference between the two materials (A) and (B) consists in the fact that the material (A) is an expanded material, while the material (B) is a non-expanded material. The expanded materials that can be used in the process according to the present invention are well known to those skilled in the art. The expanded materials mentioned above, such as (A) and (ABA) can be prepared by extrusion techniques such as foaming and casting, as well as monolayer and / or multilayer extrusion. The following examples provide a better understanding of the present invention. EXAMPLES The peeling tests (removing or removing the coating) were carried out manually in the industrial plant, since it was not possible to reproduce them in the laboratory and / or to establish analytical techniques capable of providing results that would allow to distinguish a more adequate finished product. one less adequate. The separation tests of the films of the elastomeric mass or bulk are considered positive when the film can be separated without breaking or undergoing excessive and permanent deformation. The mechanical characteristics that refer to the stress-elongation tests in the L and T directions of the finished products of types A and ABA, prepared using polyethylene, are indicated in table 1. The differences are evident, and confirm the need of having a finished product of the ABA type when it is necessary to easily separate the pebicle from the bale. The tests carried out in a (immersion mixer) Bambury confirm that it is possible to mix perfectly with rubber or rubber both films, both type A and type ABA, when consumers do not intend to separate the film from the bale.

TABLE 1 ANALYSIS TYPE OF FILM NORMA film A film ABA Thickness 100 100 100 100 ISO (micras) 4593-93 Extrusion direction MD TD MD TD laceration ASTM Elmendorf 7.5 40 30 45 D1922-93 (in N / mm) Elastic or stretch limit 10 10 ASTM (EN N / mmq) D882 - 91 Final tensile stress 10 23 21 (in N / mmq) Elomgation% 300 100 350 600 at break

Claims (1)

1. CLAIMS A process for coating and protecting elastomers, in particular EP (D) M elastomeric polymers, by applying to the preceding elastomers a coating or coating consisting of at least one layer of protective material optionally reinforced with one or more layers of reinforcement material, characterized in that: material A essentially consists of an expanded material selected from (i) linear or branched polyethylenes, (ii) ethylene vinyl acetate copolymer with a vinyl acetate content from 2 to 18%, ionomeric resins, branched propylenes and the relative mixtures. - the material B essentially consists of a non-expanded material newly selected from among (i), (ii), and the relative mixtures. The process according to claim 1, characterized in that the materials A and B consist essentially of expanded and unexpanded polyethylene, respectively. The process according to claim 2, characterized in that the polyethylenes are selected from the groups of LLDPE (linear low density polyethylenes), ULDPE (ultra low density polyethylenes) and VLDPE (very low density polyethylene). ). The process according to claim 1, characterized in that the coating consists essentially of a layer of expanded material. The process according to claim 1, characterized in that the coating consists essentially of a layer of unexpanded material covered with two layers of expanded material.