DE1115444B - Process for making films - Google Patents

Description

The invention relates to the production of films from crystallizable, linear, high polymer Propylene. Such polymers can, for example, in a manner known per se by low-pressure polymerization of propylene in the presence of catalysts from organometallic compounds and compounds of metals of the IV., V. and VI. Subgroup of the periodic system of the elements are produced.

The production of films in which a solution of the film-forming material in one layer Applied to a surface that is also heated, among other things, the solvent evaporates from the layer and the resulting film is removed from the surface is already known. With these well-known Procedures have already been used with moving surfaces. It is also already known to evaporate the solvent with the help of a hot gas and the finished films for the purpose of molecular orientation to stretch.

The invention relates to a method by which film material is made directly from crystallizable, linear, High polymer polypropylene can be produced with a certain intrinsic viscosity, so that the film produced in this way has even better mechanical and electrical properties than films which can be obtained from degraded polymerization products.

Thereafter, in a process for the production of films using polypropylene solutions, which are applied in a layer to a heated, moving surface from which the Solvent is evaporated, after which the resulting film is removed from the surface and is stretched for the purpose of molecular orientation, according to the invention crystallizable, linear, high-polymer Polypropylene with an intrinsic viscosity of 0.5 to 7, measured in tetrahydronaphthalene, in between 170 and 250 ° C boiling petroleum fractions, optionally a stabilizer for the polymer contain, used the stretching process at temperatures of 80 to 150 ° C with a stretching ratio carried out from 1: 3 to 1:12 and the film then at temperatures from 130 to Stabilized at 150 ° C. 2 to 15 seconds at this temperature is usually sufficient for treatment the end.

Compared to films made from molten polypropylene by calendering and extrusion processes the films obtained according to the invention exhibit various advantages. So if they can be stretched more easily, have a process for making films

Applicant:

Montecatini Societä Generale

per rindustria Mineraria e Chimica,

Milan (Italy)

Representative:

Dr.-Ing. A. v. Kreisler, Dr.-Ing. K. Schönwald,

DipL-Chem. Dr. phil. H. Siebeneicher

and Dr.-Ing. Th. Meyer, patent attorneys,

Cologne 1, Deichmannhaus

Claimed priority:
Italy of March 30, 1956 (No. 4831)

Enzo Di Giulio and Paolo Parrini,

Milan (Italy),
have been named as inventors

better transparency and a much more uniform thickness, and certain surface effects, such as B. embossing can be carried out on them with the greatest accuracy even on very thin films will. Since there are no internal tensions during production, the films do not warp when they are exposed to heat.

According to the invention, a polypropylene of the aforementioned type with an intrinsic viscosity of 0.5 to 7, measured in tetrahydronaphthalene, processed. The inventive method has also has the advantage that due to the relatively low temperature at which work is carried out can, only relatively small amounts of stabilizers have to be used, which according to the Invention may be included in the solution. The stabilizers can develop their effectiveness, when they are homogeneously dispersed in the solution and are not subject to the destructive influence higher temperatures to which they are exposed in processes involving a molten mass of the Polymerization product is used.

The relatively low temperatures used in the process also allow the use of

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stabilizers that otherwise could not be used.

Petroleum fractions are used as solvents, which are between 170 and 250 ° C, in particular between 190 and 210 ° C, boil. As with the manufacture Known from solutions of high polymers, the solution is preferably prepared by first the polypropylene dispersed in cold solvent and then the dispersion with stirring heated until completely homogeneous.

Claims (2)

PATENT CLAIMS: 1. A process for the production of films using polypropylene solutions, from which the solvent is evaporated, after which the resulting film from the surface is stretched away and for the purpose of molecular orientation which are applied in a layer on a moving heated surface, characterized in that crystallizable, linear, high-polymer polypropylene with an intrinsic viscosity of 0.5 to 7, measured in tetrahydronaphthalene, in petroleum fractions boiling between 170 and 250 ° C, which optionally contain a stabilizer for the polypropylene, used the stretching process at temperatures of 80 to 150 ° C with a stretching ratio of 1: 3 to 1:12 and the film is then stabilized at temperatures of 130 to 150 ° C. 2. The method according to claim 1, characterized in that one is between 190 and Petroleum fraction boiling at 210 ° C is used. Considered publications: German Patent Nos. 390 724, 619 128, 607, 700 944, 710 121, 731 433, 760 954; Swiss patents Nos. 207 764, 750;
French Patent Nos 1055770, 075423. British Patent No. 528,107; U.S. Patent Nos. 1,672,403, 2,200,001, 201 747, 2 226 186, 2 300 211, 2 321 732, 344 482. © 109 709/381 10.61