FI95817C - Process for the production of monofilaments from ternary molding compound based on thermoplastic plastics and extruded monofilaments - Google Patents

Abstract

The invention concerns a ternary moulding composition based on thermoplastics for producing drawable, high temperature resistant monofilaments by extrusion, containing partly crystalline polyarylene sulphides or oxides, wholly or partly crystalline polyamides and apolar polyfluorocarbons. <IMAGE>

Description

95817

The present invention relates to a process for producing stretchable monofilaments by extruding thermoplastic plastics-based ternary molding compound and extruding it.

Due to the versatile properties of linear polyarylene oxides and sulphides, in particular their excellent heat resistance, good mechanical properties, separation hydrolysis and chemical resistance, non-combustibility, good electrical properties and low water absorption, their use in the form of monofilaments is also required.

In particular, this invention relates to the preparation of high temperature resistant monofilaments from suitable thermoplastic plastics, such as polyphenylene-20 sulfide, having a crystallite melting point of about 285 ° C [see also Zeitschrift Kunststoffe 77 (1987) 1023-1027]. However, polyarylene sulfide fibers and monofilaments tend to be brittle due to their high degree of crystallinity. Therefore, attempts have already been made to improve the flexibility and formability of polyphenylene bisulfide for the production of monofilaments by adding polyfluorocarbons, especially polytetrafluoroethylene, as described, for example, in EP 0 221 691 and U.S. Patent 4 493 917. However, polyarylene or 30 in the conversion of binary blends of polyfluorocarbons to monofilaments, there is room for improvement even under the right extrusion conditions, as dimensional stability has been found to be unsatisfactory with high tolerances as well as strong and uneven shrinkage, uneven surface and larger diameters.

U.S. Pat. No. 4,528,335 discloses a molding compound made from polyarylene sulfides to which amorphous polyamides have been added, which are considered to include substantially non-crystalline polyamides having a degree of crystallinity of less than 30%, preferably less than 5%. due to the melting range are particularly suitable for the manufacture of injection molded articles.

The object of the present invention was to provide a molding compound from which monofilaments based on linear polyarylene oxides or sulphides can be produced, which have good extrusion properties and have reduced brittleness. In addition, in contrast to molding compositions suitable for injection molding 15 or normal extrusion, the molding materials suitable for extruding monofilaments must also be stretchable.

The invention accomplishes this object with a process and a ternary molding compound using partially crystalline polyarylene sulfides or oxides as component A, crystalline or partially crystalline polyamides as component B and apolar polyfluorolefins as component C, and the mixtures are melted and homogenized at 270 ° C. C and stretched in a ratio of 1: 3 to 1: 8 at room temperature or up to 110 ° C. The selected ternary molding compound, on the other hand, succeeds in maintaining the good properties of the polyarylene sulfides or oxides while improving workability and reducing brittleness or cold sensitivity. According to the invention-. its ternary molding compound succeeds in optimizing the products to be manufactured, in particular extruded monofilaments, which are stretched after manufacture, surprisingly, so as not to impair individual properties. When binary molding compounds are used, the improvement of one property is directly associated with a clear deterioration of the other properties, while the present invention surprisingly succeeds in compensating for the negative properties and maintaining the existing positive properties.

According to the invention, monofilaments with excellent heat resistance and usability are produced from a ternary molding composition based on thermoplastic plastics by extruding and then stretching a mixture containing 65-84% by weight of partially crystalline polyarylene sulfides or oxides as component A, or partially crystalline polyamides as component B and 15-25% by weight of apolar polyfluoroolefins as component C.

According to the invention, polyphenylene sulfide (PPS), polyphenylene oxide (PPO) or polyether ether ketone (PEEK) is used as component A, of which PPS is preferred. In particular, crystalline polyamide 6, polyamide 66 and polyamide 610 are used as component B, but also semi-aromatic partially crystalline polyamides, such as poly-m-xylylene adipamide. Of the polyamides, polyamide 66 is preferred; it provides surface improvement and more favorable elongation and strength behavior of monofilaments.

Of the apolar fluoroolefins, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoropropylene copolymers (FEP) containing 15-25 mol% of hexafluoropropene, fluoroethylene copolymers with about 5% of perfluoroalkyl vinyl ether (PFE), ethylene vinyl ether (PEP) are used in particular. ECTFE) 30 and / or ethylene-tetrafluoroethylene copolymers (ETFE), of which ETFE is preferred. The apolar polyfluorolefins used are characterized by extremely low insulation-loss coefficients. At the same time, they improve the extrusion and stretching properties of the molding compositions and the chemical properties of the monofilaments as well as the flexibility, etc.

4,95817

Balanced monofilaments according to the invention are obtained using PPS, PA 66 and ETFE, the composition preferably having the features of claim 10.

Surprisingly, it has been found that even small amounts of selected polyamides are sufficient to improve the flexibility of the monofilaments prepared according to the invention, which at the same time improve the cold resistance of the molding composition and counteract the brittleness of the polyarylene sulfides or oxides. In particular, PA also smoothes the rough surface of polyarylene sulfides.

In the process according to the invention, molding compositions containing 65-84, in particular 72-82% by weight of component A, 1-10, in particular 1-5% by weight of component B and 15-25, in particular 17-23% by weight, are preferably used for the preparation of monofilaments. by weight of component C. When the mixture contains 80-74% by weight of PPS, 2-4% by weight of PA 66 and 22-18% by weight of ETFE, PPS-based monofilaments with balanced properties are obtained, PPS while maintaining the essential characteristics of 20.

In order to produce monofilaments with good heat resistance by extrusion and subsequent stretching, (partially) crystalline thermoplastics having a crystallite melting point of more than 240 ° C are preferably used.

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The melting and homogenization of the ternary molding compositions is preferably carried out in the temperature range 285-305 ° C, possibly also at a higher temperature.

The monofilaments obtained are characterized by good mechanical strength, flexibility, good heat resistance, advantageous • abrasion friction behavior, dimensional stability, fairly good chemical resistance, excellent hydrolysis resistance, non-combustibility, good electrical properties and low water-resistance properties as well.

35 5 95817

Monofilaments can be modified in many ways and used in particular as paper machine wires and drying tapes, filter fabrics in the chemical industry, electrical engineering and electronics as needle fabrics for hot gas dust removal, in fabric structures, etc. textiles.

The invention is illustrated by Figure 1, which shows a monofilament, and by an example.

The ternary molding compound was mixed with polyphenylene sulfide, ETFE and PA 66 in a ratio of 77: 20: 3, plasticized and melted in a single screw extruder 15 at 295 ° C and extruded into an unstretched monofilament with a diameter of 0.50 mm ± 0.01 mm. . After cooling to a temperature below 95 ° C, the monofilament is stretched to about three times its length to form a stretched monofilament having a diameter of 0.31 mm ± 0.01 mm. Stretched monofilament has the following properties:

Tensile load: 24-29 N Elongation at break: 35-40%

Shrinkage in boiling water after 5 min: 25 2.3-3.7%

Shrinkage at 150 eC after 5 min: 10%.

The monofilament produced is characterized by a small variability in the diameter of the monofilament, a smooth surface and flexibility.

For comparison, a monofilament of polyphenylene sulfide and ETFE according to EP-A-0 221 691 was prepared and stretched under similar conditions in a ratio of 80:20. The reference monofilament has the following measured properties: 95817 6

Tensile load: 33-38 N Elongation at break: 25-60%

Shrinkage in boiling water after 5 min: 0.5-4.7% 5 Shrinkage at 150 ° C after 5 min: 6.3-13.3%.

The reference monofilament had a rougher surface and lower flexibility than the monofilament of the invention. In addition, the diameter 10 of the stretched reference monofilament ranged from 0.02 to 0.06 mm. 1

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Claims (10)

1. A process for producing stretchable monofilaments by extruding a thermoplastic plastic material based ternary molding, characterized in that partially crystalline polyarylene sulfides or oxides are used as component A, crystalline or partially crystalline polyamides are used as component B and apolar polyphenols are used as component C, the blends are melted and homogenized in an extruder at a temperature above 270 ° C and the extruded monofilaments are stretched in the ratio 1: 3 - 1: 8 at room temperature or at a maximum of 110 eC. 2. A process according to claim 1, characterized in that the molding composition contains: 65-84% by weight of partially crystalline polyarylene sulfides or oxides, 1-10% by weight of crystalline or partially crystalline polyamides and 15-25% by weight -% of apolar polyfluorolefins. 20 3. A process according to claim 1 or 2, characterized in that polyphenylene sulfide, polyphenylene oxide or polyether ether ketones are used as component A in the molding compound. 4. A process according to any one of claims 1-3, characterized in that polyamide 6, polyamide 66, polyamide 610 or semi-aromatic partially crystalline polyamides are used as component B in the molding compound. 5. A process according to any one of claims 1-4, characterized in that ethylene-tetrafluoroethylene copolymer, polytetrafluoroethylene, tetrafluoroethylene-perfluoro-propylene copolymer, fluoroethylene copolymer containing about 5% perfluoroalkylvinyl ether and / or ethylene-chloro trifluoroethylene copolymer are used as the copolymer copolymer as copolymer. . Process according to any one of claims 1-5, characterized in that the molding mass contains: 95817 72 - 82% by weight of partially crystalline polyarylene sulfide or oxide, 17-23% by weight of apolar polyfluorolefins and 1-5% by weight of crystalline or partially crystalline polyamides. 7. Monofilament, characterized in that it is made by extrusion and then stretching a ternary molding mass containing: 65-84% by weight of partially crystalline polyarylene sulfides or oxides as component A, 1-10% by weight of crystalline 10 or partially crystalline polyamide as component B and 15-25% by weight of apolar polyfluorolefins as component C. Monofilament according to claim 7, characterized in that it contains as component A in the molding mass 15 polyphenylene sulfide, polyphenylene oxide or polyether ether ketone, as component B in the molding polyamide 6, polyamide 66, polyamide 610 or poly-m-xylylene adipamide and as component C in the mold mass ethylene-tetrafluoroethylene copolymer, polytetrafluoroethylene, tetrafluoroethylene-perfluoropropene copolymer, ethylene-chloro trifluoroethylene copolymer and / or fluoroethylene copolymer containing about 5% perfluoroalkylvinyl ether. The monofilament according to claim 7 or 8, characterized in that the molding mass contains: 72 - 82% by weight of component A,. 1-5% by weight of component B and 17-23% by weight of component C. Monofilament according to any one of claims 7-9, characterized in that the molding mass contains: 74-80% by weight of polyphenylene sulfide, 2-4% by weight of polyamide 66 and 18-22% by weight of ethylene-tetrafluoroethylene copolymer .