CS258675B1 - Composition on polyamide-6 base - Google Patents

Abstract

The purpose of the solution is to improve the physical and the mechanical properties of the modified polyamide by adding polytetrafluoroethylene powder. Improving sliding properties increase in temperature resistance, toughness and water absorption is reduced by adding silicone oil, which ensure good adhesion of polytetrafluoroethylene particles in polyamide. The solution can be used for sliding production parts with increased demands for strength, tenacity, temperature resistance and dimensional accuracy at damp humidity, especially in engineering industry.

Description

The present invention relates to a polyamide-6 blend which is characterized by improved slip properties, increased heat resistance, toughness and reduced water absorption by the addition of polytetrafluoroethylene powder and silicone oil. Such a mixture can be further modified by filling with glass fiber or mineral fillers, flame retardants and the like.

It is known that increasing the slipperiness, i. j. The reduction of the coefficients of friction for plastics is achieved in polyamide-6 by the addition of graphite, molybdenum disulphide or polytetrafluoroethylene, which is described in Japanese Patent 5,018,663, 5,5082,156, 9,088,755 and Eur. No. 160,914.

In this process, however, along with an increase in slipperiness, some of the mechanical properties of the polymer, in terms of tensile strength, ductility and toughness, deteriorate. An increase in hot shape stability can be achieved by filling with mineral fillers, e.g. talc according to Japanese Patent Nos. 5,203-960 or 5,210,761 and 5,9050,221 by addition of 30 to 40 wt. glass fiber.

The notched toughness of polyamide-6 can be increased e.g. modification of grafted polyethylene according to German Patent No. 2,722,270, the addition of rubbers according to Belg. U.S. Patent No. 4,019,085 or acrylic modifiers of U.S. Patent 4,041,103, Eur. U.S. Patent 8,126 or Japanese Patent 5,404,361. Japanese Patent 5,205,653 discloses reducing water absorption by the addition of chemically modified polypropylene. The disadvantage of all these processes is that each of them modifies only one of the endpoints, while, moreover, they usually change in an undesirable manner.

These drawbacks are overcome by a composition based on polyamide-6, polytetrafluoroethylene powder and, optionally, glass fibers, mineral fillers, flame retardants and any other additives, characterized in that it contains, in addition to the above, silicone oil of methyl or methylphenyl type of viscosity 50 to 250 mPa. s at 20 ° C, for a total content of the basic components of 65 to 98.9 wt. % polyamide-6, 1 to 30 wt. % polytetrafluoroethylene powder and 0.1 to 5 wt. silicone oil.

The advantage is that due to the very high adhesion between polyamide-6 and the polytetrafluoroethylene particles due to the addition of silicone oil, the heat stability is increased and the energy transfer from the polyamide matrix to the polytetrafluoroethylene resilient particles is improved and the energy transfer from the polyamide matrix is improved. toughness of the composite. High adhesion forces also prevent moisture penetration into close proximity to the polytetrafluoroethylene particles and consequently reduce the water absorption of the system.

Example 1

Polyamide blend prepared by mixing in a fluidic mixer and granulating at a melt temperature of 260 ° C and injected onto standard test bodies at a temperature of 260 ° C, respectively. pressing to 1 mm thick plates at the same temperature, consisting of polyamide-6 and polytetrafluoroethylene, has the following characteristics:

PTFE content by weight 0 5 10 15 ' 20 Coefficient. kinetic friction 0.22 0.21 0.18 0.15 0.12 Heat Shape Stability ° C 117 120 119 124 123 Tensile strength MPa 30.2 30.3 29.0 27.5 25.2 Ductility% 59 51 54 42 20 Notched toughness of Charpy kj / m ² 13.3 14.7 16.1 12.2 8.6 Incompatibility after 100 hrs water% 9.3 8.2 7.6 6.9 5.9 Example 2 puts 1 s 0.5 % wt. metylfe- nyl silicone oil having a viscosity of 130 to 190  Polyamide mixture prepared as in mPa. with (Lukoil MF). PTFE content by weight 5 10 15 20 KDET. kinetic friction 0.22 0.18 0.14 0.13 Shape stability at heat ° C 133 135 135 130 Tensile strength MPa 33.4 32.7 31.6 31.1 Ductility% 54 60 64 59 Vrubová húž. Charpy kj / m ² 24.8 46.6 36.3 29.9 Soak after 100 h at water% 8.0 7.3 6.1 5.0

β

Example 3 lays 1 with an addition of 15 wt. PTFE powder and various silicone oil contents

The polyamide blend prepared as in the following has the following characteristics:

Contents of Lukoil MF 0.1 2.0 Coefficient. kinetic friction 0.15 0.12 Shape stability at temperature ° C 130 128 Tensile strength MPa 28.3 27.6 Ductility% 47 93 Vrubová húž. Charpy kj / m ² 22.3 51 Water absorption after 100 h% 6.9 6.0

The object of the invention can be used to produce sliding parts with increased demands on strength, toughness, temperature resistance and dimensional accuracy at varying humidity, especially in the engineering industry.

Claims (1)

A composition based on polyamide-6, powdered polytetrafluoroethylene and, optionally, glass fibers, mineral fillers, flame retardants, and possibly other additives, characterized in that it contains, in addition to the above components, a methyl or methylphenyl type silicone oil having a viscosity of 50 to 250 mPa. with at 20 ° C, with a total content of basic components of 65 to 98.9 wt. % polyamide-6, 1 to 30 wt. % polytetrafluoroethylene powder and 0.1 to 5 wt. silicone oil.