CZ281697A3 - Material for coating wires - Google Patents

Abstract

A wire coating composition comprises 100 php (parts per hundred parts of polypropylene) polypropylene polymer or copolymer, 1 to 20 php of polyethylene wax and 100 to 200 php of magnesium hydroxide which is provided with a hydrophobic coating. The wire coating composition does not contain any halogen and is essentially free of phosphorous and phosphorous salts.

Description

The present invention relates to a wire coating composition. The term wire as used herein includes both wires and cables.

BACKGROUND OF THE INVENTION

It is common to provide wires and cables with a polymeric insulating coating. Such coatings are often made of halogenated polymers such as polyvinyl chloride (PVC).

The main problem associated with PVC and other halogenated polymers is that a large amount of toxic, acidic and highly corrosive halogen smoke is released during combustion. Therefore, halogen-free polymer blends have been developed for coating cables or wires. Examples of such compositions are described, for example, in EP 082407A, EP 488381A and US 5032321. These and other prior art halide-free coating compositions based on mixtures of thermoplastic radius and

The mineral filler suffers from inadequate abrasion resistance, inadequate electroinsulating properties and inadequate temperature stability. These coating compositions have a maximum temperature range of only 70-80 ° C. In addition, the extrusion rate for mixtures of the type described in EP 082407A, EP 488381A and US 5032321 can be only one fifth of the PVC extrusion rate. Similar compositions containing an intumescent flame retardant system, such as ammonium polyphosphate, also exhibit inadequate electrical resistance due to the fact that the flame retardant enters moisture and thus increases the electrical conductivity of the material. It is known that conventional phosphorus-based flame retardants are added in relatively large amounts, usually up to 40 php in the case of ammonium polyphosphate.

A drawback of the red phosphorus-based system is that the cable sheathing has a strong red coloration, which is a disadvantage for electric cable sheathing in general.

It is an object of the present invention to provide a recyclable and / or reprocessable halide-free coating composition having improved abrasion resistance, improved electrical insulation and thermal resistance properties without deteriorating other physical properties such as tensile strength or flexibility.

SUMMARY OF THE INVENTION

According to the present invention, a wire coating composition is provided comprising a propylene polymer or copolymer, polyethylene wax and a hydrophobically coated magnesium hydroxide, wherein the wire coating composition is free of any halide and substantially free of phosphorus, phosphorus compounds and phosphorus salts.

The term essentially is used herein to mean that the composition does not contain phosphorus or its compounds or salts thereof or has a phosphorus content of less than 320 ppm.

The wire coating composition of the present invention exhibits the desired coating characteristics, but is easily recyclable compared to some PVC compounds. The coating composition of the present invention further provides the desired electrical insulation while being flexible,

non-flammable, temperature stable up to more than 125 ° C, abrasion resistant, easily extrudable and recyclable.

The components of this mass are ideally present in the following ratio:

polypropylene 100 php (parts per hundred parts of polypropylene);

magnesium hydroxide of 100 to 200 and ideally (coated) substantially 140 php; and polyethylene 1 to 20 and ideally substantially 10 php.

Coating compositions are particularly useful for wires in motor vehicle engines, as these wires are exposed to high temperatures and contact with water and liquids such as gasoline, diesel, oil, salt. and antifreeze. It is essential that the wire coating materials below the engine hood have a temperature rating greater than 100 ° C, at which temperature the coating should remain stable and retain the electrical insulation properties. The coating compositions of the present invention have a temperature load greater than 125 °.

Polyethylene wax is added to improve abrasion resistance. Hard high molecular wax components would _? should provide excellent abrasion resistance, but may also increase the tendency to crack in the coating under stress. When the material is a relatively low molecular weight, polyethylene wax improves the abrasion resistance of the coating without adversely affecting the other properties of the coating.

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Magnesium hydroxide acts as a filler and flame retardant. In order to overcome the moisture trapping problems associated with intumescent flame retardant systems, magnesium hydroxide particles are coated with a hydrophobic material such as an alkylsilane, for example trimethoxysilane or triethoxysilane. The coating improves the adhesion between the filler particles and the polymer matrix, improves the abrasion resistance of the coating and, most importantly, due to its hydrophobic nature, improves the moisture resistance of the coating, thereby maintaining the electrical insulation properties. Magnesium hydroxide is also stable at high temperatures, and its small surface area is due to its low viscosity. This material is therefore easy to process.

A preferred amount of 140 php magnesium hydroxide content provides an ideal balance between flame retardancy and flexibility. The high filler content provides an excellent flame retardant effect. However, at the same time, the coating becomes much less flexible, so that the coated wire fails in a standard conductivity test in which the wire is tightly wound (usually around a 1 mm diameter core) and stored in hot water (usually 80 ° C) while under high tension. . If the coating is not flexible enough, it will burst at the tops of the threads.

A further advantage of the composition of the present invention is that it can be extruded onto a wire or cable using existing extrusion equipment at speeds similar to the speeds at which PVC coatings are extruded.

By using the coating compositions of the present invention, cost savings can be achieved by utilizing the high thermal loadability of such coatings. Usually, the copper wire becomes considerably hot as a result of electrical current. The high thermal loadability of the coating means that thin coatings of the coating can be used on thin wires, saving expensive copper.

A preferred embodiment of the present invention comprises adding to the mass of the combined mixture of an antioxidant derived from phenol and an antioxidant based on phosphite. These antioxidants are present in an amount of only from 0.1 to 0.5 php. Such phosphite contents are low enough (OTO ppm) to have negligible moisture retention capacity.

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Such compositions maintain good processability without adversely affecting the other physical properties of the coating. This aids the further reprocessing of the coating and thus improves the recyclability of these compositions.

Optionally, the polymeric compositions of the present invention may further include additives such as stabilizers, plasticizers, lubricants, and other flame retardants.

In order that the present invention may be more readily understood, exemplary specific embodiments are described in detail below.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Mass: 100 php of propylene polymer ^{* 1}

140 php Magnifin H5KV ^{2 *} coated with AMEO-T 'php polyethylene wax ⁴ polymer includes 20 php Appryl 3060 MMS (trade name of Atochem for propylene copolymer) and 80 php Moplen

D50-G (Himont trade name for propylene homopolymer). Appryl 3060 MMS has a melt flow index

444

4

0,5 g per minute at 230 ° C and 21,6 kg. Moplen D50-G has a melt flow index of 0.3 g per minute at 230 ° C and a weight of 21.6 kg.

Magnesium hydroxide - trade name of Martinswerk.

⁵ octyltriethoxysilane coupling agent - trade name of Huls.

the trade name of the wax is A-C 9 / 9A (trade name of Allied Wax). This wax has a dropping temperature of 115 ° C and

2_q a density of 0.93 g / cm ³ .

The mass was extruded onto a standard metal wire used for automotive electrical cable applications at a speed of approximately 700 m per minute using conventional extrusion equipment for PVC coated cables to form a coated cable with a cross-sectional area of 2.5 mm. Such cables could normally be used as conductors to an alternator or battery in a motor vehicle.

The test results of this coating are as follows:

Test Requirement Standard Result Insulation Conductive cross-sectional area 1.5 - 2.5 mm ² under load 10 - 80 N DIN 72551 Point 3.3.2 39 N Abrasion behavior measured in the number of head cycles while maintaining min. thickness 2,5 mm ^: 1500 cycles DIN 72551 Point 3.3.3 > 3000

• · ········ · · ·

Heat resistance below load (measured as depth of penetration coating after heating to 125 ° C for 4 hours) 0.15 mm DIN 72551 Point 3.4.2 > 0.25 mm Max. heat shrinkage 4% DIN 72551 Point 3.4.2 2.5% Voltage strength po for 30 minutes 5 kV DIN 72551 Point 3.5.3 passed Min. resistivity at temperature 70 ° C 10 ¹⁰ ohms per cm DIN 72551 Point 3.6.1 3,2.10 ¹⁴ Thermal shock (150 ° C after 48 hours) Voltage strength 1 kV DIN 72551 Point 3.6.2 passed Cold strength (-33 ° C) Voltage strength 1 kV DIN 72551 Point 3.6.3 passed Storage in motor Multi-Region (UAE) 10 W-50) for 24 hours at 90 ° C Voltage strength 1 kV DIN 72551 Point 3.6.2 passed Storage in brake liquid (Teyes ATE DOT 3) for 24 hours at 90 ° C Voltage strength 1 kV DIN 72551 Point 3.6.2 passed Storage in motor Four Star gasoline (see DIN 51601) for 24 hours at temperature rooms Voltage strength 1 kV DIN 72551 Point 3.6.2 passed

499

Storage in motor Voltage strength 1 kV DIN 72551 passed diesel (visa DIN 51601) Point 3.6.2 for 24 hours at room temperature

Example 2

Mass: 100 php of propylene polymer ¹

140 php Magnifin H5KV coated with AMEO-T php polyethylene wax polymer includes 40 php Appryl 3060 MMS and php Moplen D50-9.

The mass of Example 2 also passed the appropriate tests which were carried out in conjunction with the mass of Example 1.

It should be understood that the embodiments described above have been presented for the purpose of illustration only. Many modifications and changes are possible within the scope of the present invention.

Claims (5)

A wire coating composition comprising a propylene polymer or copolymer, polyethylene wax and a hydrophobic coated magnesium hydroxide, wherein the wire coating composition is free of any halide and substantially free of phosphorus compounds, phosphorus salts and phosphorus salts. Wire coating composition according to claim 1, characterized in that the coated magnesium hydroxide is present in an amount ranging from 100 to 200 php. 3. The wire coating composition of claim 2 wherein the coated magnesium hydroxide is present in an amount of substantially 140 php. Wire coating composition according to any one of the preceding claims, characterized in that the polyethylene wax is present in an amount ranging from 1 to 20 php. 5. Mass for coating wires according to claim 4, in y z n and no u se se se team that polyethylene wax Yippee present in an amount of substantially 10 Php- 6. Mass for coating of wires according to any of The preceding claims, characterized in that the hydrophobic coating material comprises an alkyl silane. Wire coating composition according to any one of the preceding claims, characterized in that the composition comprises from 0.1 to 0.5 php of an antioxidant.