DE2930521A1 - POLYAETHYLENE MOLDS FOR THE INSULATION OF METAL LADDERS - Google Patents

Description

VEB Leuna-Werke Merseburg, March 12, 1979

»Walter Ulbricht" DC.Do/Sch

LP 7849 a

Title of the invention

Polyethylene molding compounds for insulating metallic conductors Field of application of the invention

The invention relates to polyethylene molding compounds used for insulation metallic conductor, particularly suitable for very small conductor cross-sections and very high withdrawal speeds sin'U The molding compounds are used as an insulating material for the Wire and telecommunication cable insulation are used and serve as electrical transmission lines in telecommunications.

Characteristics of the known technical solutions

The increase in pull-off speeds for cable core insulation leads to an increase in the roughness of the insulation surface with high pressure polyethylene as the insulating material Conductor cross-sections additionally reinforced · It is known that the roughness (melt fracture) on the insulation surface when using the same tool to reduce by adding high-pressure polyethylene other ethylene polymers and / or Mixed polymers made from olefins are added.

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LU.

knows that already by adding low pressure polyethylene compared to high-pressure polyethylene, an improvement in terms of a smooth insulation surface at a higher take-off speed the pure high-pressure polyethylene can be achieved without the requirement for smooth insulation surfaces to meet very high withdrawal speeds. According to DE-OS 1794103, further improvements are to be achieved as a result that the high-pressure polyethylene specially polymerized low-pressure polyethylene with a density about 0.960 g / cm and small amounts of a copolymer Ethylene with at least one alpha-olefin with 3 to 8 carbon atoms and a density above 0.945 cm. The low-pressure polyethylene and copolymers are so described that for their production and to achieve a certain property profile, d. H. a very high one Molecular weight with a certain residual elasticity, special catalysts based on silyl chromate can be used.

Ea is also known from DE-OS 1719252, the mixtures made of high pressure polyethylene and special high molecular weight low pressure polyethylene Add small amounts of polypropylene without adverse effects · This is also the case after DE-OS 1679654 known, with smooth insulation surfaces Take-off speeds to increase further by adding the high-pressure polyethylene proportions of polypropylene and propylene-ethylene copolymers can be added.

The disadvantage of the known polyethylene molding compound is the need to use specially made high polyethylenes Density and copolymers that make the production of such molding compounds economically unfavorable and the fact that these products only up to a maximum of 1500 m / min take-off speed and conductor dimensions of 0.5 mm diameter can be used. It is also known that mixtures of high and low pressure polyethylene and / or polypropylene represent a heterogeneous (Jemisch. The disadvantage of such molding compounds is particularly clearly when used for very high processing speeds

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ORIGINAL tNSPECTED

and smaller conductor dimensions, as there can be segregation phenomena and thus deterioration in properties occurs.

Object of the invention

The aim of the invention is to provide polyethylene molding compounds for insulating metallic conductors, in particular for small conductor cross-sections and very high take-off speeds to produce with smooth insulation surfaces.

Explain the essence of the invention

The invention is based on the object of producing polyethylene molding compounds that are used in the insulation of metallic conductors with smooth insulation surfaces up to at least 25oo m / min withdrawal speed and can be used for ladder pressure gauges from 0.6 mm to 0.3 mm.

This object is achieved by duru-U polyethylene molding compounds for insulating metallic conductors made of low and high density polyethylene, polypropylene and copolymers of ethylene with alpha-olefins with the addition of anti-aging agents, the molding compounds according to the invention being 94 to 50% by weight, preferably 85 to tO wt .-%, of a Hochdruckpolyäthylens 5 to 45 wt .-%, preferably iO to 25 wt .-%, of a Niederdruckpolyäthylens and 0.5 to 10 wt -.% _t preferably from 1 to 5 wt .-%, of a hydroxyl - And / or contain olefin copolymer containing ester groups.

The molding compositions advantageously additionally contain 0.5 to 6% by weight, preferably 1.5 to 3-5% by weight, of a polypropylene.

Products can be used as olefin copolymers those from unsaturated hydrocarbons such as ethylene or its homologues and esters of alpha, beta-unsaturated Acids such as vinyl acetate, ethyl acrylate and / or methyl methacrylate exist.

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The olefin copolymer advantageously contains 2 to 35% by weight, preferably 10 to 15% by weight, of ester groups. It is also advantageous to use completely or partially saponified olefin copolymers and their saponification products. High pressure polyethylene can be the products produced by the customary methods of radical ethylene polymerization under high pressure with a Sohmelzindex of 0.1 to 0.5 g / 10 min and a density of 0.915 to 0.935 g / cm, preferably 0.919 to 0.925 g / cm , can be used. The low-pressure polyethylene used has densities of 0.939 to 0.960 g / cm, preferably 0.945 to 0.955 g / cm, and a melt index of 0.1 to 4.0 g / 10 min (5 kp / 109 ⁰ C), preferably 0, 5 to 2.0 g / 10 min. The polypropylene advantageously has a density of 0.900 to 0.920 g / cnr and a melt index of 0.1 to 4 g / 10 min (5 kp / 190 ⁰ C) i preferably from 0.4 up to 1.0 g / 10 min.

The molding compounds are produced in the melt on conventional, preferably continuously operating homogenizing units. The components can be pre-washed in a high-speed mixer or dosed separately with known dosing systems. The components can be homogenized either on single-screw extruders or on twin-screw extruders, the temperature program during the homogenization being set in such a way that 200 ^° C. is only slightly exceeded. Production using the hot die-cutting process is advantageous. In addition, anti-aging agents, in particular thermal stabilizers and / or copper deactivators, fillers, lubricants and / or pigments can be added to the molding compositions.

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Embodiments

The physical parameters were determined as follows:

Density according to TGL 14075
Melt index according to TGL 20996

The roughness of the insulation surface was determined visually and graded into 5 quality levels: smooth, slightly wavy, wavy, rough, very rough.

example 1

80 kg high pressure polyethylene with a melt index i _{o A} r = 0.3 g / 10 min and a density of 0.921 g / cm, 20 kg low pressure polyethylene with a melt index i, - _Q = 0.5 g / 10 min and a density of 0.949 g / cm and 1 kg of ethylene vinyl acetate copolymer with 13% ester group content and a melt index of ± ₂ «r = 2.2 g / 10 min are mixed in the usual way with the addition of 0.1 kg of antioxidant KS, homogenized in a twin-screw extruder and then granulated.

The molding compound has a melt index of _{10 (} - = 0.23 g / 10 min and a density of 0.931 g / cm the plasticized mixture is transported to the 90 ° deflection head. The melt is fed to an annular gap formed by the quill and die and sprayed onto the conductor. The coated conductor is then fed to a cooling device and wound onto a drum. The process described above is used to produce the polyethylene - Molding mass at 2550 m / min withdrawal speed sprayed onto a conductor with a diameter of 0.40 mm and an insulation thickness of 0.2 mm The contact length is the distance between the quill tip, entry of the

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Head into the melt and the end of the injection molding tool. As a result, the conductor pressure holding forces are low and resulting conductor cracks are excluded.

The surface of the insulation is smooth, although with a conductor small diameter is coated using a very short tool

Example 2

The components of example 1 are made by a multicomponent metering Homogenized in the above mixing ratio in a single-screw extruder with a homogenizing screw. the The resulting molding compound is fed to the processing extruder as in Example 1 and a take-off speed of 2500 m / min sprayed onto a conductor with a diameter of 0.5 mm and an insulation thickness of 0.23 mm. The isolation is also smooth and free from roughness in this case.

Example 3

65 kg high pressure polyethylene with a melt index i _o .r «0.24 g / 10 min and a density of 0.923 g / cm, 35 kg low pressure polyethylene with a melt index i, - _n = 1.1 g / 10 min and a density of 0.945 g / ciir and 2 kg ethylene-vinyl acetate copolymer with 5.5 wt .-% ester group content and a melt index ip ^ V «1.8 g / 10 min are mixed with 0.1 kg antioxidant KS in the usual way, 'on a twin screw extruder homogenized and fed to a processing plant.

The insulation surfaces obtained with these components according to the method described in Example 1 at processing speeds of 2500 m / min and a used conductor diameter of 0.4 mm are smooth and for the further processing process fully suitable.

Example 4

90 kg high-pressure polyethylene with a melt index i _{o Λ (} - = 0.25 g / 10 min and a density of 0.919 g / cm, 10 kg

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q ₀ ⁰ O = ⁸ 5 g / 10 min | - druckpolyäthylen having a melt index i _cn = 0.3 g / 10 min and a density of 0.958 g / cm and 4 kg teilvereeiftea Jithylen-vinyl acetate copolymer having a melt index i ₂ -j5 ( and a residual ester group content of 3 »5% by weight are premixed with 0.1 kg of antioxidant KS and fed to a homogenizing extruder for homogenization mm with processing speeds of 2550 m / min analogous to Example 1.

The insulation is smooth and shows no signs of melt fracture.

Example 5

100 kg high pressure polyethylene with a melt index ^ ₂ 16 ⁼ 0.28 g / 10 min and a density of 0.920 g / cm ³ , 35 kg low pressure polyethylene with a melt index ί _{κ n} «0.45 g / 10 min and a density of 0.950 g / cm, 2.5 kg of acetylene-vinyl acetate copolymer with 14% ester group content and 3 kg of polypropylene with a melt index i, - _n = 0.8 g / 10 min and a density of 0.910 g / cm are added with 0.1 kg of antioxidant KS mixed in the usual way and homogenized in a twin screw extruder and then granulated. The molding compound wii-u is sprayed onto a conductor with a diameter of 0.3 mm and an insulation thickness of 0.15 mm on a processing plant for the production of insulated wires at a withdrawal speed of 2500 m / min. A die is used as the injection molding tool, which limits the length of contact between the conductor and the melt, which is necessary for the conductor retention forces, to £ 9 mm. The coated wire shows a closed and smooth insulation surface.

Example 6

70 kg high pressure polyethylene with a melt index ig 16 ⁼ 0.35 g / 10 min and a density of 0.922 g / cm ³ , 30 kg low pressure _{polyethylene with a melt index i K n} a 0.8 g / 10 min and a density of 0.956 g / cm, 3.5 kg partially saponified ethylene-vinyl lace ta t copolymer with a residual content of vinyl

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acetate of 4 »8 wt .-% and 4 kg of polypropylene with a Melt index i_ _ = 0.9 g / 10 min and a density of Q »910 g / cm with the addition of 0.1 kg of antioxidant KS mixed in the usual way and homogenized on a twin screw extruder. The molding compound is analogous to Example 1 onto a metallic conductor 0.3 mm in diameter with a Insulation thickness of 0.15 mm at .fb pulling speeds sprayed up to 2500 m / min. The insulation surface is smooth and without any roughness.

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Claims (8)

mm * ■ »· * · t »> · A« t · ft Invention claim (iw Polyethylene Pormmassen for the insulation of metallic conductors made of low and high density polyethylene, polypropylene and copolymers of ethylene with alpha-olefins with the addition of anti-aging agents, characterized in that the molding compounds are 94 to 50% by weight, preferably 85 to 70% by weight, of a high pressure polyethylene, 5 to 45% by weight, preferably 10 to 25% by weight, of a Low pressure polyethylene, and 0.5 to 10 wt .- #, preferably 1 to 5% by weight, of a hydroxyl and / or ester group-containing Contain olefin copolymer. 2. Polyethylene molding compounds according to point 1, characterized in that that the molding compounds additionally contain 0.5 to 6% by weight, preferably 1.5 to 3.5% by weight, of a polypropylene 3. Polyethylene molding compounds according to items 1 and 2, characterized that the olefin copolymer of ethylene or ■ its homologues and esters of unsaturated acids, preferably vinyl acetate, ethyl ^ acrylate and / or methyl methacrylate consists. 4. Polyäthylen-FormmaaBeu according to point 1 to 3 »characterized in that that the olefin copolymer contains 2 to 35% by weight, preferably 10 to 15% by weight, of ester groups. 5. Polyethylene molding compounds according to items 1 to 4, characterized in that that the olefin copolymer or mixtures of olefin copolymers completely and / or partially saponified are. 6. Polyethylene molding compositions according to items 1 and 2, characterized in that the high-pressure polyethylene has a melt index of 0.1 to 0.5 g / 10 min and a density of 0.915 to 0.935 g / cm ³ , preferably 0.919 to 0.925 g / cm ³ , has. 030010/0660 7. Polyethylene molding compounds according to points 1 and 2, characterized in that that the low-pressure polyethylene has a density of 0.939 to 0.960 g / cm, preferably from 0.945 to 0.955 g / cm, and a melt index of 0.1 to 4.0 g / 10 min, (5 kp, 190 ° 0), preferably from 0.5 to 2.0 g / 10 min. 8. Polyethylene standard materials according to items 1 and 2, characterized in that the polypropylene has a density of 0.900 to 0.920 g / cm and a melt index of 0.1 to 4.0 g / 10 min (5 kp / 190 ⁰ C), preferably from 0.4 to 1.0 g / 10 min. ■ 030010/0660