EP0439733A2 - Improved polyamide- or polyester fibres with improved characteristics - Google Patents

Abstract

The invention relates to polyamide or polyester fibres with improved characteristics, obtained by addition of polyarylene sulphides in amounts of 0.1 to 10% by weight, preferably 0.3 to 5% by weight, and subsequent melt-spinning and customary fibre aftertreatment.

Description

The invention relates to polyamide or polyester fibers with improved properties, obtained by adding polyarylene sulfides in amounts of 0.1 to 10% by weight, preferably 0.3 to 5% by weight and subsequent melt spinning and customary fiber post-treatment.

The use of thermoplastic polyamides (e.g. PA-6 and -66) and polyesters (e.g. polyethylene terephthalate) for the production of fibers is known (see e.g. Encyclopedia of Polymer Science & Engineering, 2nd Edition, Wiley Interscience, John Wiley and Sons, New York).

The fibers generally have the known good properties, such as high tensile strength / tear strength, elongation at break, comfort and good appearance.

They are used, for example, in the textile sector, as carpet yarn, tire cord, fishing lines and in other areas.

For a wide variety of applications, it would now make sense to further improve their inherently good properties, in particular the strength.

Surprisingly, it has now been found that the stretchability and strength of polyamide or polyester fibers can be significantly improved by using certain polymers in small amounts, whereby further properties such as rigidity and heat resistance can be increased.

• 1) mindestens 90 Gew.-% üblicherweise verwendeter aliphatischer Polyamide bzw. Polyalkylenterephthalate und
• 2) 0,1 bis 10 Gew.-% Polymerer mit dem überwiegenden Baustein (I)
  
  wobei

  Ar

  einen gegebenenfalls substituierten Arylenrest bedeutet,

  sowie gegebenenfalls
• 3) bis 30 Gew.-%, bezogen auf 1) + 2), üblicher Hilfs- und Zusatzstoffe.

The invention therefore relates to drawn fibers composed of polymer mixtures

• 1) at least 90% by weight of commonly used aliphatic polyamides or polyalkylene terephthalates and
• 2) 0.1 to 10% by weight of polymer with the predominant building block (I)
  
  in which

  Ar

  represents an optionally substituted arylene radical,

  and if necessary
• 3) to 30% by weight, based on 1) + 2), of conventional auxiliaries and additives.

The polymers 2) are arylene sulfide homo- and copolymers. The poly-p-phenylene sulfide (PPS) (II) is preferred.

In particular, those polyarylene sulfides 2) are used which were directly condensed to high molecular weights in solution in one step without solution, but instead in oxidative molecular weight build-up. Methods for their production are known, see e.g. EP 0 171 021.

Corresponding polyarylene sulfides are commercially available, for example, under the trade names Tedur® and Fortron®.

Polymers 2) with melt viscosities (at 320 ° C and 100 s⁻¹) of approx. 5 to 500 Pa.s. are suitable. In particular, the melt viscosity should be 10 to 200 Pa.s.

Suitable polyamides 1) are the polyamides (PA) usually used for the production of fibers by melt spinning, for example PA-6, 66, 610, 46, 1212, 6T6, 6T / 6, and various copolyamides or mixtures of the polyamides mentioned.

PA.6, Pa.66 and mixtures thereof or copolyamides based on these are preferred. PA6 or copolyamides based on PA.6 are particularly preferred.

The usual melt-spinnable polyesters based on terephthalic acid and aliphatic glycols, for example polyethylene terephthalate, polybutylene terephthalate and poly (1,4-cyclohexylene dimethylene terephthalate), are suitable as polyester 1).

Polyethylene terephthalate is preferred.

The polyesters 1) can optionally, in addition to terephthalic acid and the glycols, also modifying amounts of other monomers, e.g. Isophthalic acid, adipic acid and diethylene glycol.

Polyamides are preferred over polyesters. Particularly preferred component 1) are PA6, 66 and mixtures or copolyamides based thereon.

For the production of the fibers according to the invention, polymer mixtures are used which can be produced in various ways, for example by compounding (for example using a kneader or extruder), by producing the polyamide or polyester in the presence of the polymers 2) or by mixing the granules and subsequent ones Spinning.

The actual fiber production (all types of fibers such as filaments, monofilaments, wires, staple fibers, "bulk continuous filament" and others are to be understood more under the term "fibers") is carried out as usual, preferably by melt spinning; all usual post-treatment methods such as stretching, fixing, crimping, dyeing etc. can be used.

In the context of the invention, drawn fibers are understood to mean those fibers which are produced, for example, by drawing twists, drawing winches in filament yarns, by roll or calender drawing in fiber cable processing or by spinning, e.g. also in the course of a rapid spinning process, stretched and thus oriented. All other stretching methods are also suitable in principle. Such drawn fibers have an increased orientation and crystallinity compared to standard injection molded or extrusion molded articles.

All substances commonly used in fiber production are suitable as additives 3), e.g. Matting agents (TiO₂ and others), UV stabilizers, pigments, dyes, nucleating agents, antioxidants, optical brighteners, dyeing aids, sizing and others.

The polyamides or polyesters 1) may also contain monomers which increase the dyeability of the fibers; such monomers are known.

Alloys of polyamides or polyesters and polyarylene sulfides are known, see, for example, our own unpublished patent applications Le A 26 662 and 26 894.

WO 86/03212 describes polymer alloys made of polyamide 46 and at least 5% by weight of polyarylene sulfides, which are said to have very good mechanical properties. The cited application discloses that polyamide 6 and 66 are not sufficiently compatible with polyphenylene sulfide to achieve good mechanical properties. Comparative Example 3 shows that an alloy of polyamide 6 and 15% PPS shows very poor extrusion behavior due to the insufficient compatibility and that the test specimens have a poor appearance and unusually low values for tensile strength and flexural modulus. The application mentioned contains no reference to the use of the molding compositions for the production of fibers.

In US 4,292,416, polyarylene sulfides are described as nucleating agents, ie additives which increase the degree of crystallization, for polyamides, this being shown only for a special polyamide made from terephthalic acid and a C₁₀-diamine mixture. The addition of the PPS generally lowers the tensile strength and flexural modulus; the elongation at break and the impact strength usually increase significantly. This extremely unusual combination of effects is applied to all polyamides. The application contains no indication that the stretchability or strength of fibers based on aliphatic polyamides (in particular PA6 or copolyamides based on PA6) can be significantly increased by adding PPS. In particular, a decrease in strength should be expected according to US 4,292,416.

When using polymeric multicomponent systems, in particular in the case of partially crystalline polymers, for the production of fibers, separation phenomena usually occur during stretching and thus when building up a higher orientation. This is coupled with poor phase coupling and poorer mechanical properties of the fibers.

The invention is based on the surprising finding that only a narrow range of the latter is suitable for significantly improving the properties (stretchability, strength) of the fibers by means of polyarylene sulfide additives. According to the invention, this is preferably 0.3 to 5.0%, particularly preferably 0.5 to 3.0, in particular 0.6 to 2.5%. According to the invention, the stretchability and the strengths of, for example, PA6 fibers are increased in this narrow quantity range; For example, the strength of PA6 fibers can be increased by 25 to 30%, whereby the rigidity and the heat resistance can also be improved. The elongation of the fibers is practically unchanged. The effects mentioned, which form the basis of the present invention, are unexpected and cannot be derived from the prior art. In particular, the improvements in fiber properties according to the invention in the light of WO 86/03212 are surprising, which teaches that no homogeneous mixtures can be produced from PA6, 66 and PPS due to insufficient compatibility and that corresponding alloys show extraordinarily poor strength and stiffness values.

The fibers according to the invention can be produced by all customary processes, generally by means of the melt. All usual post-treatment methods can be used. For the production of fibers, reference is made, for example, to Encyclopedia of Polymer Science and Engineering, 2nd Edition, Wiley Interscience, John Wiley and Sons, New York, and H. Klare, Technology and Chemistry of Synthetic Fibers from Polyamides, VEB Technik, Berlin 1954 . The melt spinning can take place both above and below the melting temperature of the polymers 2).

Because of their very good properties, the fibers according to the invention are a valuable addition to the prior art. They can be used alone or, if appropriate, in combination with other natural or synthetic fibers. They are suitable for all applications of polyamide and polyester fibers, especially for those that require high strength.

The following examples with typical ingredients in typical amounts illustrate the invention without restricting it.

Examples Examples 1 to 4 (not according to the invention) Production of PA6 / PPS compounds according to Le A 26 662

A polyamide 6 (η _rel ≃ 4.0; 1% in m-cresol, 25 ° C) was at 285 ° C and a throughput of 30 kg h⁻¹ with 1, 2 and 5 wt .-% PPS (39 Pas, 310 ° C, 1000 s⁻¹) or compounded without PPS via a twin-screw extruder (ZSK 53). Viscosities and work input values of the extruder can be found in Table 1.

Examples 5 to 8 (not according to the invention) Production of PA6 / PPS compounds according to Le A 26 894

Caprolactam and water (0.5 l without PPS; 0.6 l with PPS) as well as 100, 200 or 500 g PPS (the sum of the weights of caprolactam and PPS was always 10 kg) (melt viscosity: 31 Pas at 306 ° C and 1000 s⁻¹) were placed in a 25 l autoclave. After three nitrogen equalizations, the mixture was heated to 200 ° C. and held under autogenous pressure for 1 hour. The mixture was then depressurized to normal pressure, 40 l h⁻¹ of nitrogen passed over and simultaneously heated to 270 ° C (in the presence of 1 and 5% PPS 280 ° C). The reaction times were 4 to 7 hours until the desired melt viscosity was reached.

Analytical data of the samples can be found in Table 1.

Examples 9 to 16 (according to the invention)

The polyamides of Examples 1 to 8 were melted and spun in multiple threads in an extrusion spinning apparatus. The spun material thus obtained was drawn.

Spinning conditions and fiber data are summarized in Table 2.

As the examples show, the PPS-modified fibers have improved properties (degree of stretch, strength), these being most pronounced in the range from 1 to 2% addition.

The degree of stretching of the fibers should be> 1: 2, e.g. 1: 2-1: 10, preferably 1: 2.5 to 1: 7.5, in particular 1: 3 to 1: 6, up to the maximum degree of stretching at the stretching temperature used.

Claims (7)

Drawn fibers and filaments from polymer blends containing A) at least 90% by weight of commonly used aliphatic polyamides or polyalkylene terephthalates and B) 0.1 to 10% by weight of polymer with the predominant building block (I)

in which Ar represents an optionally substituted arylene radical, and if necessary C) up to 30% by weight, based on A) + B), of conventional auxiliaries and additives. Fibers according to Claim 1, characterized in that the polymer B) is preferably poly-p-phenylene sulfide (PPS) (II)

is used. Fibers according to Claim 1, containing preferably 0.3 to 5.0, particularly preferably 0.5 to 3.0 and in particular 0.6 to 2.5% by weight, polymer B. Fibers according to Claim 1, containing as polymer A) (preferably) polyamides such as PA6, 66 and mixtures thereof or copolyamides based on these, or (less preferably) polyesters such as polyethylene terephthalate. Fibers according to claim 1, containing as additives C) matting agents, UV stabilizers, pigments, dyes, nucleating agents, antioxidants, optical brighteners, dyeing aids, sizes and others. Drawn fibers (filaments, monofilaments, wires, staple fibers, "bulk continuous filament" and others) according to claims 1 to 5 with increased strength. Use of polymer mixtures A) at least 90% by weight, preferably 95 to 99.7% by weight, particularly preferably 97 to 99.5% by weight and in particular 97.5 to 99.4% by weight of commonly used aliphatic polyamides, in particular PA6, 66 and copolyamides thereof, or polyesters, in particular polyethylene terephthalate, and B) 0.1 to 10% by weight, preferably 0.3 to 5.0% by weight, particularly preferably 0.5 to 3.0% by weight and in particular 0.6 to 2.5% by weight %, of polymers with the predominant building block (I)

in which Ar is an optionally substituted arylene radical, and if necessary C) up to 30% by weight, based on A) + B), of conventional auxiliaries and additives for the production of stretched fibers with an increased maximum degree of stretch and improved strength by melt spinning the mixture and stretching with a degree of stretch> 1: 2.