Synthetic material and process for the production thereof

Abstract

A material for the production by extrusion or molding or calendering of light articles has a chemical formulation comprising at least a thermoplastic polymer. A predetermined amount of polymeric microspheres containing isopentane is added to said at least a thermoplastic polymer. A process for producing said material comprises a first step during which the thermoplastic polymer is mixed to further components (such as thermal stabilizers and/or costabilizers and/or additives) and a second step during which the mixture is granulated in order to obtain a granular compound. At the end of the first step, and advantageously immediately before the beginning of said second step, a predetermined amount of polymeric microspheres containing isopentane is added to the mixture. Said material is used for the production by injection molding or extrusion or calendering of light articles in the shoe industry, particularly of shoe soles.

1 . Material for the production by estrusion or molding or calendering of light articles, the chemical formulation of said material comprising at least a thermoplastic polymer, characterized in that a predetermined amount of polymeric microspheres containing isopentane is added to said at least a thermoplastic polymer.  
     
     
         2 . Material according to    claim 1   , characterized in that the thermoplastic polymer is a PVC resin.  
     
     
         3 . Material according to    claim 1    or    2   , characterized in that the microspheres are coated by metha-acrylonitrile-polymethylmethacrylate.  
     
     
         4 . Material according to anyone of the preceding claims, characterized in that it comprises at least a plasticizer which is added to the starting formulation.  
     
     
         5 . Material according to    claim 4   , characterized in that said at least a plasticizer to be added is di-2-ethyl-esil-phthalate.  
     
     
         6 . Material according to anyone of the preceding claims, characterized in that the starting formulation of said material comprises thermal stabilizers and/or costabilizers and/or additives suitable for improving the molding operation of the material and/or its workability.  
     
     
         7 . Material according to    claim 6   , characterized in that said thermal stabilizers which are used in the starting formulation of said material are selected from the group comprising barium and zinc or calcium and zinc or barium and lead.  
     
     
         8 . Material according to    claim 6   , characterized in that said costabilizer which is used in the starting formulation of said material is epoxidate oil of soya.  
     
     
         9 . Material according to    claim 6   , characterized in that the formulation comprises stearic acid which is used as additive suitable for improving the molding of the material and/or its workability.  
     
     
         10 . Material according to anyone of the preceding claims, characterized in that it allows the production of molded or extruded or calendered articles having a density value comprised in the range from 0.2 g/cm 3  to 0.65 g/cm 3 .  
     
     
         11 . Material according to    claim 10   , characterized in that said density value is comprised in tha range from 0.4 g/cm 3  to 0.5 g/cm 3 .  
     
     
         12 . Material according to anyone of the preceding claims, characterized in that most microspheres contained in the granules of said material are integer and not expanded before the successive molding or extrusion stage of the finished article.  
     
     
         13 . Process for the manufacturing of a material based on a thermoplastic polymer suitable for being molded or extruded for the production of several articles, said process comprising a first step in which said thermoplastic polymer is mixed to further components such as thermal stabilizers and/or costabilizers and/or additives suitable for improving the molding and/or the workability of the material and/or plasticizers, a second step during which the mixture is granulated in order to obtain a granular compound, characterized in that at the end of the first step, and advantageously immediately before the beginning of said second step, a predetermined amount of polymeric microspheres containing isopentane is added to the mixture.  
     
     
         14 . Process according to    claim 13   , in which the granular material is obtained by means of a multistage extruder-granulator, characterized in that said predetermined amount of polymeric microspheres containing isopentane is added to the mixture inside of said extruder-granulator and, more specifically, inside of one of the latest stages of the extruder before the obtainement of the granulated material.  
     
     
         15 . Process according to    claim 13    or    14   , in which the granulation is obtained by means of an extruder-granulator, characterized in that said extruder-granulator is operated at the lowest temperature technically suitable for obtaining steady links among the components of the mixture introduced inside of the extruder, and at rate suitable for avoiding the breaking of the microspheres.  
     
     
         16 . Use of a material according to anyone of the preceding claims for the production by injection molding or extrusion or calendering of light articles in the shoe industry, particularly of shoe soles.