IL97073A - Polyamide/polyester synthetic fibers and processes for the preparation thereof - Google Patents

Description

POLYAMIDE/POLYESTER SYNTHETIC FIBERS AND PROCEDURES FOR THE PREPARATION THEREOF ."SYNTHETIC FIBRE AND RELATED PRODUCTION ΓΠΟΟΕΡυΐΐΰ" The present invention relates to a new synthetic continuous filament or tuft fibre, obtained by spinning a two-component polyamide/poly-ester polymer.

Synthetic fibres are made from polymers by chemical polymerizing, polycondensation and polyaddition procedures; that is by typical chemical procedures which join monomeric groups together, by means of a synthetic process.

In the present case, the polyester or polyamide polymers are melted down and extruded through a one or multi-holed spinneret and then the filaments obtained are solidified. After extrusion, the fibres undergo a drawing or drawing and texturising operation.

The drawing may be at hot or at ambient temperature, depending on the type of the polymer making up the fibre; in the case of polyamides the drawing process is usually carried out at ambient temperature; in the case of polyesters hot drawing is generally used.

The synthetic fibres prepared by the general method described above, have shrinking and dyeing properties and a specific textile behaviour known to all.

The aim of the present invention is to obtain a synthetic continuous filament or tuft fibre. This fibre possesses both polyamides and polyesters characteristics, and in the fibre the above properties can be varied according to the reciprocal percentages of the two components, in such a way that it can be used for special articles, for technical uses: e.g. textiles for sails, textiles for electric motor covers, as well as for fabrics in general, such as those for clothing and soft furnishings.

This aim has been achieved by the creation of a synthetic continuous filament or tuft fibre composed of a two-component polymer with varying percentages of polyamide/polyester . These percentages vary from 1% to 99% of polyamide and from 99% to 1% of polyester.

The fibre, subject of the present invention, is obtained by means of a procedure which foresees mixing the two components, during the spinning phase, in order to obtain the two-component fibre. The spinning described is usually carried out at temperatures which vary from + 250°C to + 320°C, that is, between the normal thermal profiles of polyamide and polyester polymers. The process then foresees subjecting the pick-up obtained after spinning, to a drawing or drawing and texturising process.

Drawing can be either at ambient temperature (using the technology typical of polyamides) or hot (using the technology typical of polyesters) ; the method is chosen according to the percentage of the single components of the polymer yarn.

Ambient temperature drawing is usually carried out at a temperature of between + 10°C and + 30°C; hot drawing is usually carried out at a temperature of between + 80°C and + 170°C.

According to the type of drawing performed, the drawn fibre, subject of the present invention, has varying shrinkage and textile behaviour. For example, 50% shrinkage can be obtained.

The texturisation or drawing and texturisation operation does not cause variations in the properties of the fibre, except in morphological terms.

The texturisation or drawing and texturisation operation can be performed in various ways, among which we Would point out: by means of a false twisting system (with a small spindle or by means of discs or belts), by means of a blade system, by means of the Knit de Knit system, by means of the Stuffer Box system, by means of the Ban-Lon system, or by means of the air system (Taslan).

The invention will now be explained by referring to some examples of manufacture relating to PES/PAM spinning by means of the extrusion and pick-up of the partially oriented yarn (POY) obtained by mixing polyester and polyamide 6 during the polymer fusion phase.

The following polymers are used: a) Polyester (PES): the base polymer was a full lustre polymer with an intrinsic viscosity (ETA)/20°C = 0.640 DL 1. Before entering the extrusion phase, this polymer was dried in a continuous plant until chip residual humidity was 30/40 ppm (depending on the length of time in the plant) .

The drying plant was a MIAG-type countercurrent vertical tower whose crystalliser was separate from the drier. b) Polyamide (nylon 6): the base polyester polymer was mixed with a full lustre chip (PAM) whose relative viscosity, determined in 96% sulphuric acid at 20°C, was * |^(ETA) rel 20°C = 2.70.

This polyamide was previously batch-dried in nitrogen until- the residual humidity of the chips was 400 ppm.

The problem of the spinner is to find a system which allows the temperature and speeds of spinning and picking-up to be adjusted to the various stages.

Our mixing method can be carried out by means of all known and used mixing systems, the most common being: - volumetric dosers for chips or powders; - gravimetric dosers for chips or powders; - weight-volumetric dosers for the injection of molten material.

For example, it is possible to use a spinning plant composed of: a) a PES/PAM dosing system: a volumetric doser capable of releasing the correct proportion of chips of the two polymers directly into the mouth of the extruder; once the weight of the chips to be dosed from each of the mouths of the doser has been established, an electronic control device ensures that the system continues to keep the input given to the desired dosage ratio; b) a horizontal, 90 mm diameter 0 Barmag extruder with five heating zones and a LT system in front of the auger; c) a mixer for homogenising the molten mass, equipped with two heating zones which can be used in the case that greater homogeneity is to be given to the final product; d) a heated molten polymer distribution spider; e) a Barmag SP spinning plant composed of: 1) steam-heated diathermic oil spinning heads; 2) sixteen 2.4 cc titration pumps; 3) 32 spinneret packages, each composed of a spinneret, a pre-spinneret with flow distributors, a metal grid filter, a metal sand container and a baffle for the sand container; f) a cooling chamber with an air flow perpendicular to the path of the thread; g) an enzyme catalyser located at the base of the cooling chamber, consisting of distribution nozzles and 0.06 cc/revolution dosing pumps ; h) if necessary, interlacing machines before the pick-up; i) a Barmag SW4SLD lapping machine with a feeding godet, a drawing frame roller and a grooved roller.

EXAMPLE 1 PES/PAM spinning of a 30 filament (85% polyester and 15% polyamide) 135 dtx POY destined for texturisation with a final count of 78 dtx.

The table below shows some of the parameters adopted during the various working phases: TABLE 1 30 filaments 135 dtx WORKING PARAMETERS % polyamide - 15% DRYING PES drying air temperature 165° C Time spent in drier 6 hours 2 Extruder head pressure 130 kgp/cm Temperature: Zone 1 270° C Zone 2 270° C Zone 3. 270° C EXTRUSION " Zone 4 270° C " · Zone 5 270° C Mixer temperature Zone 1 270° C Zone 2 270° C Spinning boiler temperature 282° C Circular spinneret diameter 100 mm FILTRATION Number of holes 30 AND Extrusion speed 16.8 m/i SPINNERET Capillary diameter 0.30 mm height 0.60 mm 2 PAK pressure 110 kgp/cm Temperature 22° C COOLING Speed at outlet 0.9 m/sec Relative humidity 50% % Emulsion 12% ENZYMATION Dosing pump capacity 0.06 cc/rev " " revolutions/minute 20 rpm INTERLACING Interlacer air pressure 3.0 atm AND Pick-up speed 3190 m/m PICKUP - - The product obtained by using the method of the present invention is an above-average quality yarn.

EXAMPLE 2 Using the same procedure as in Example 1, PES/PAM spinning of a 30 filament (85% polyester and 15% polyamide) 280 dtx POY destined for texturisation with a final count of 165 dtx.

The table below shows some of the parameters adopted during the various working phases: TABLE 2 30 filaments 280 dtx WORKING PARAMETERS % polyamide - 15% DRYING PES drying air temperature 165° C Time spent in drier 3 hours Extruder head pressure 130 kgp/cm2 Temperature: Zone 1 285° C " Zone 2 285° C " Zone 3 285° C EXTRUSION Zone 4 280° C Zone 5 280° C Mixer temperature Zone 1 285° C Zone 2 285° C Spinning boiler temperature 292° C Circular spinneret diameter 100 mm FILTRATION Number of holes 30 AND Extrusion speed 34.8 tn/i SPINNERET Capillary diameter 0.30 mm height 0.60 mm 2 PAK pressure 120 kgp/cm Temperature 22° C COOLING Speed at outlet 1.2 m/sec Relative humidity 50% % Emulsion 12% ENZY ATION Dosing pump capacity 0.06 cc/rev " " revolutions/minute 35 rpm INTERLACING Interlacer air pressure 3.0 atm AND Pick-up speed 3190 m/m PICKUP Also in this case, it appears that the product obtained by means of the method of the present invention has properties which are superior to those of. products produced by previous methods.

It is obvious that it is possible to spin different compositions of the two products by appropriately modifying speeds and temperature.

In each case, the resulting product will have different dyeing, tactile and shrinking characteristics.

More details concerning each of the aspects characterising the said yarn are given below.

DYEING This can be done by means of a simple polyester dye, a simple polyamide dye or by using both. In each case, the results will be different in terms of colour and intensity, and these results can be varied by changing the proportions of the two products in the composition of the yarn.

It should be noted that polyamide melts in formic acid. When a fabric made partially or wholly with this yarn is immersed in formic acid, part of the polyamide content is lost and this results in a fabric which has a different weight and feel from that of the untreated' raw material. Furthermore, various dyeing effects can be obtained by varying the length of time in which the formic acid is left to act.

The use of such yarns, handled with imagination by an expert technician, provides the opportunity for greater creativity in an extremely wide range of fields, particularly that of fabrics for clothing or soft furnishings.

SHRINKAGE As previosly stated, this yarn can be drawn by using either polyamide (cold drawing) or polyester (hot drawing) technologies, with clear-cut differences in terms of behaviour. These differences not only relate to the well-known differences in dyeability produced by the two techniques but also to the possibility of managing (or rather, controlling) the mechanical behaviour (shrinkage) of the yarn for the successive fixing phase.

In practice, it is possible to obtain varying degrees of shrinkage (from almost zero to about 50%) according to the proportion of the two components in the final composition and according to whether the yarn is hot or cold drawn.

In practice, these characteristics of the yarn could find appropriate technical application in yarns of fabrics for clothing or soft furnishings, where the characteristics mentioned above could lead to lower weaving costs (because the yarn is shrunk during the subsequent finishing phase of the completed fabric, reaching the desired compactness downstream of the weaving process) or could give the finished product a different and more original appearance (thanks to the effects of shrinking and dyeing).

"FEEL" AND TOUCH It is well known that two similar fabrics (one made of 100% polyamide and the other of 100% polyester) have a completely different "feel".

Fabrics made from the new yarn fall between these two extremes in accordance with the different proportions of the two components.

Furthermore, it is possible to obtain a yarn (and therefore a fabric) which is softer to the touch and more similar to those, composed of microfibres, with obvious savings in terms of production.

As is known, microfibres are individual fibres with a count of less than 1 denier making up a continuous filament or tufted yarn.

In our case, without needing to produce microfibre threads and while maintaining a higher individual fibre count, a higher-quality, softer "feel" can be obtained.

Claims (6)

- 12 - 97073/2 WHAT IS CLAIMED 18:

1. A synthetic, continuous, homogeneous filament yarn, composed of a polyamide/polyester polymer mixture in percentages varying from 1 to 99% of polyamide and from 99 to 1 percent of polyester, characterized in that said yarn is absolutely homogeneous, having been obtained by mixing and melting the two different polymers used, polyamide and polyester, before spinning, whereby the molecules of said two different polymers are intimately mixed.

2. A yarn according to claim 1, whenever incorporated and used for technical articles, fabrics for clothing, knitted fabrics, soft furnishings and textiles in general, according to the reciprocal percentages of the drawing and/or drawings and texturization technologies adopted.

3. A process for obtaining a yarn according to claim 1, comprising mixing melted polyamides and polyesters in order to obtain a two-component polymer; heating of such a two-component polymer, during the spinning phase, at temperatures usuay of between 250°C and 320°C, and the drawing operation or drawing and texturizing of the pick-up in order to obtain the yarn which is the subject of the present invention.

4. A process according to claim 3, characterized in that the drawing phase is called out at ambient temperatures or at elevated temperatures, according to the percentages of the components of the two-component polymer, and according to the characteristics it is desired to confer to the yarn. - 13 97073/2

5. A process according to claim 3, characterized in that the drawing operation is followed by a twisting operation, or substituted by a drawing and texturization operation of the POY yarn or by texturization of the drawn yarn.

6. A synthetic tuft fiber, made up of the same two-component polymer as descrdibed in claim 1, which will maintain the characteristics of the continuous filament fiber, particularly as far as concerns shrinkage, dyeing and the possibility of dissolving one component in a suitable solvent. For the Applicant WOLFF/ BREGMAN AND GOLLER