DD203915A1 - DISPOSABLE POLYETHYLENE MOLDING - Google Patents

Abstract

Verschaeumbare Polyaethylen-molding compounds, which are suitable for the insulation of wires and cables. Such lines are used as high frequency cables in the communication transmission. There are verschaeumbare Polyaethylen-molding materials developed, the high aging resistance, a degree of expansion of greater than 60%, a dielectric loss factor of less than 2 times 10 & exp-4! revealed. The molding compositions contain Hochdruckpolyaethylen, polypropylene and / or Niederdruckpolyaethylen, and a blowing and processing aid and an anti-aging agent.

Description

VEB Leuna-Werke Leuna, 12. 2. 1982

"Walter Ulbricht"

LP 81 142

Title of the Invention Foamable Polyethylene Molding Compositions Field of the Invention

The invention relates to Yerschäumbare polyethylene Fonnmassen that are suitable for insulation of wires and wires »The foamable molding materials are characterized by a high expansion capacity, a low dielectric loss factor and a good aging resistance · Such molding materials are used in telecommunications, in particular for the production of high frequency communication cables ·

Characteristic of the known technical solutions

The use of reversible polyolefins for the insulation of wires leads to the improvement of the dielectric properties.

Thus it is known to combine polyethylene with other polyolefins using special blowing agents to improve the dielectric properties. Thus DS-OS 2 615 317 describes that for the production of insulating materials with improved electrical properties.

2379 79

a product of 100 parts of polyethylene is used, W3lch.es consists of 10 to 90! Dellen Hochdruckpolyäthylen and 90 to 10 parts Uiederdruckpolyäthylen and as blowing agent 0.5 to 1.5 parts of a Qxybis-Cbenzolsulfohydrazids) * Furthermore, according to DB-OS No. 2,615,636 discloses that, when using from 0.5 to 1.5 parts of an aromatic sulfohydrazide, ζ · Β · methylenebisbenzenesulfohydrazide) and the plastic compositions described in DE-OS 2 615 317, a low dielectric loss factor and a damping of the conduit are achieved which is equivalent to that produced by gas injection,

HachteJLL the known molding compositions is that the foaming power is not sufficient and thus the applications of such insulating materials are limited »STach DE-OS 2,853,626 is known to use for producing a foamed insulation plastic materials from at least two polyolefins ,, wherein a component is a swelling ratio has greater than 55% and at least 20% of the insulation layer constitutes · the foaming takes place with the addition of azodicarbonamide and / or 4 "4 ^t -0sybis (benzenesulfonyl hydrazide) as a chemical blowing agent and / or an inert gas ~ propellent such as nitrogen, argon and carbon dioxide Gas »To increase the mechanical strength, the foamed insulation additionally obtains a solid polyethylene sheath · Significant disadvantage. Such molding compositions is the formation of large cells and a non-uniform cell structure, so that in addition to the dielectric loss factor and the Füllmassenbeständigkeit in particular the dimensional stability and aging behavior of the foamed insulation layer not sufficient a ± ad

Object of the invention

The goal of the invention is. Foamable polyethylene molding compositions for the insulation of wires and cables with hochespandierter insulation layer, low dielectric loss factor

-.3- Z.J / a / 3 υ

and to develop high aging resistance · Presentation of the essence of the invention

The invention has for its object to produce foamable polyethylene molding compositions, which after the isolation process an expansion of> 60 % and at the same time have a dielectric loss factor of <2 * 10 "^ high aging resistance * This task 'is by foamable polyethylene molding compounds made of polyethylene lower

/ r>, and high density,. Polypropylene, chemical blowing agents and / or inert gas blowing agents, according to the invention, the molding compositions 90 to 50 Gew * - #, preferably 80 to 60 wt .-%, of a Hochdruckpolyäthylens, 5 to 40 Gew * - $, preferably 10 to 30 wt * -% of a polypropylene and / or up to 40 percent "~% of a" iederdruckpolyäthylens, 0.5 to 2 percent by _#! -% of a chemical blowing agent, 0.05 to 1.5 percent "-% of a Verarbeitungsjailfsmittels and 0, 03 to 0.3% by weight of an anti-aging agent, containing »

As a chemical blowing agent, the molding compositions may contain combination with a processing aid *. For a favorable Yerschäumungsverlauf and to form very small and uniform cavities contain the molding

_) mass advantageously as a processing aid PoIytetrafluoräthylen with a particle size of less than 5 ^ Um and / or freshly precipitated finely disperse silica "As aging inhibitors contain the molding materials with Torteil products based on sterically hindered Alkylhydroxyphenylalkylhydrazine for effective protection against thermal and metal catalytic degradation * The contained in the molding compositions High-pressure polyethylene can, after radical polymerization under high pressure with densities in the range from 0.916 to 0.925 g / cm and a melt index of less than 2.5 g / 10 min. be prepared, \ φ / azodicarbonamide

As polypropylene, the molding compositions contain products with a density of 0.90 to 0.92 g / cm and a melt index of small he 2 g / 10 min. (2.16 kp / 463 K).

237979

As low pressure polyethylenes, the molding compositions contain products made in the presence of mixed catalysts having densities of 0.939 to 0.950 g / cm and a melt index of small 3.0 g / 10 min.

The molding compositions of the invention can be ζ · _Β β obtained by melt blending · Suitable gate directions include "continuous kneaders · - The individual components can be used individually and / or as a concentrate at different locations or the Homogenisieraggregat .. the Yerarbeitungsanlage be supplied · The production of the concentrate is carried out in suitable mixing units at temperatures below 423 K in order to prevent foaming of the molding compound. The achievement of a highly foamed insulation with good centricity of the insulating sleeve and high strength values is substantially facilitated by the fact that with a corresponding temperature control and setting of the cooling conditions u * a · the formation of a high degree of fineness through the Fonnmassen- composition is adjustable ·

Ausführungsbeispie1e

example 1

A polyolefin mixture of 65 kg high-pressure polyethylene (density 0.92 g / cm- ³ , melt index 2,, 16: 0.35 g / 10 min), 21.5 kg polypropylene (density 0.905 g / cm, melt index 5.0: 0.75 g / 10 min) and 13.5 kg bodice pressure polyethylene. (Density 0,94β g / cm, melt index 5,0i 2.2 g / 10 min) was with a mixture of 1.05 weight _e - .Azodicarbonamid% and 0.05 Nominal jS-H = S'tearyl-J3 3,5-di-t.ert, butyl-4-hydroxy-phenylpropylhydrazin ~ Polyte.trafluoräthylen%, particle size of less than 1 m JX, ladder-sprayed 0.25 weight as anti-aging agent as well as "to a 0.65 mm thick, foamed and then the insulation layer tested "The adhesion of the insulation layer to demieiter was good" The degree of expansion of the insulation layer was 61 %, with a cell size of less than 15 / Am with a dielectric loss factor of 1.6.10. The elongation values after aging of IQ-Ta

- ₅ - 237979 O

at 363 K showed only a drop of less than 10%. Example 2

Sin Polyolef ingemisch. except 65 kg high-pressure polyethylene (density 0.92 g / cm, melt flow rate 2.16, 0.2 g / 10 min), 35 g polypropylene (density 0.905 g / cm, melt flow rate 5.0: 1.2 g / 10 min) and 0.8% by weight. A mixture of polytetrafluoroethylene and finely dispersed silica was dispersed in the melt with 1.15% by weight of azodicarbonamide and 0.1% by weight of I, H '-bis-.beta.-SjS-di-tert-butyl-hydroxyphenylpropionylhydrazine as an anti-aging agent ·. The melt was sprayed onto a conductor of 1.4 mm thickness * The foamed insulation layer with round cross-section after testing revealed a. Degree of expansion of 65.5%, a cell size of less than 10 / xm, a dielectric loss factor of 1.65 x 10 and had a high mechanical strength.

Example 3

A polyolefin mixture according to Example 1 was homogeneously distributed in the melt using 1.3% by weight azodicarbonamide, 0.65% by weight of a mixture of polytetrafluoroethylene and finely dispersed silica and 0.07% by weight of an aging protection agent according to Example 1.

The melt was sprayed onto a 0.75 mm thick conductor and then the insulation layer was tested. The foamed insulation layer after testing gave a degree of expansion of 62 % and a dielectric loss factor of 1.95. 10 "· The insulation sheath showed no noticeable decrease in the elongation values (<5 %) after aging for 10 days at 363 K. *

Claims (7)

237979 O Invention claim 1 · Yst foamable polyethylene Pormmassen of low and high density polyethylene, polypropylene, chemical blowing agents and / or inert gas blowing agents, characterized in that the molding compositions 90 to 50 wt .-%, preferably 30 to 60 wt .-% -, one High-pressure polyethylene, 5 to 40% by weight, preferably 10 to 30% by weight, of a polypropylene and / or up to 40% by weight of a low-pressure polyethylene, 0.5 to 2% by weight of a former blowing agent, 0.05 to 1.5 parts by weight of a processing aid and 0.03 to 0.3 parts by weight of an aging inhibitor 2 "Yerschäumbare Polyäthylen JOrmmassen according to item 1, characterized in that they contain as Yerarbeitungshilfsmittel polytetrafluoroethylene in a particle size of less than 5 microns and / or finely dispersed silica, 3 · Y-expandable polyethylene molding compositions according to item 1, characterized in that they contain azodicarbonamide as blowing agent 4 * Yerschäumbare Po ^ ethylene Pormmassen according to item 1, characterized in that they contain as aging inhibitors a product based on sterically hindered Alkylhydrosyphenylalkylhydrazine. 5. terschaumbare Po ^ äthylen-Porminassen to item 1, characterized in that this is a high-pressure polyethylene having a density of 0.916 to 0.925 g / cm ui
of less than 2.5 g / 10 min. Density from 0.916 to 0.925 g / cm and with a melt ind 6. Yst foamable polyethylene molding compounds according to point T, characterized in that they comprise a polypropylene having a density of 0.90 to 0.92 g / cm and a melt index of less than 2 g / 10 min (2.16 kg / 463) contain. 237979 O 7. Foamable polythene molding compositions according to Pun & t 1, characterized in that they contain a Fiederdruckpolyäthylen with a density of 0.939 to 0.950 g / cm ³ with a Schmela index of less than 3.0 g / 10 min *