JPH0686683B2 - Polyurethane multifilament elastic yarn - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to melt-spun smooth multifilament elastic yarns made of polyurethane having a Shore hardness of 80 to 95 °.

Processes for making melt spun polyurethane elastic yarns comprising at least 85% by weight of segmented polyurethane are known. Such yarns were practically unusable because of stickiness after spinning. The relief is achieved by chemically changing the polyurethane.

Methods by which the tackiness of extruded endless yarns can be chemically reduced are known (DE-A 2204470).

This known method either incorporates a polyimide or adds a polymer melt into the polymer chain.
The endless yarn produced using the polymer obtained needs to be wound up at a very low speed and is stretched in the second step. The properties of the yarn obtained are not shown at all.

Additives have the effect of lowering the molecular weight, which in turn lowers the viscosity of the melt, and on the other hand has a negative effect on the elastic properties, elongation at break and strength of the yarns produced. At a nominal winding speed of 160 m / min, productivity is insufficient and uneconomical.

DE-A 1944507 discloses a multistage process in which the tackiness of polyurethane elastic yarns is reduced in the spinning process. In this method, melt extrusion is performed in the first stage,
The resulting yarn is quenched and solidified, drawn in the second stage by at least 30% and in the next stage relaxed by at least 50% before winding. It explains in detail based on theoretical considerations that the tackiness of the yarn increases when the tension relaxation rate is small, that is, when the winding speed is high.

According to this method, the melt spun yarn is stretched and then relaxed again. The process of this method suggests that the finished, fully cooled elastic yarn is present on the take-off roller. This yarn exhibits the properties typical of polyurethane elastomers; because of its high elasticity, the yarn can no longer be stretched in the original sense, but it can be stretched significantly and this elongation is reversible. The elongation treatment according to DE-A 1944507 does not significantly affect the properties of the yarn.

Heretofore, all attempts to produce polyurethane elastic systems under economical conditions by melt spinning, i.e. at high spinning speeds, have the point that extruded filaments stick as soon as the spinning speed increases beyond a defined limit. Was a failure.

Surprisingly in the present invention, contrary to popular theory, the polymer and stretching conditions are chosen such that irreversible stretching occurs, the stress relief / relaxation is completely abandoned and finally the winding It has been found that at higher speeds, the known sticking between the yarns and between the fibrils can be avoided, and yarns with high modulus and better processability can be produced.

Quenching the yarn after melt spinning is a more expensive process step and changes the properties of the yarn.

The economics can be significantly increased by using high winding speeds at high spinning temperatures. This makes it possible to produce extremely fine fibril yarns.

It is an object of the invention to provide a high modulus, high strength multifilament elastic yarn which can be economically produced by melt spinning and in which the fibrils do not stick together.

In the present invention, the elastic yarn made of polyurethane having a Shore hardness of 80 to 95 ° has a modulus of 10 to 40 cN / tex, and a breaking elongation of 80 to 80 relative to the length of the undrawn yarn.
The above-mentioned object is achieved by a polyurethane multifilament elastic yarn characterized by being 300%.

The polyurethanes used to make the elastic yarns of the present invention include extrudable aromatic diisocyanates such as 4,4'-diphenyl-methane diisocyanate (M
Those consisting of DI) and linear polyethers such as polytetramethylene glycol or aliphatic polyesters such as polybutylene adipate or polycaprolactone diol are preferred. Also suitable are block polymers consisting of alicyclic diisocyanates such as hexahydro-MDI and linear segment polyethers. This polymer is particularly well-known as a medical device (Medizinische E
Suitable for use with insatze). A suitable polyurethane has a softening point of 180 to 230 ° C and a hardness (Shore A) of
The temperature is 80 to 95 ° and the density is 1.1 to 1.25 g / cm ³ . This hardness plays an important role on the tackiness of polyurethane yarns.

Polyurethanes of the same series (PUR) such as polyether- or polyetherester- or polyesteramine-urethanes are likewise introduced, melt-spun and processed into elastic yarns, as long as they have sufficient melt stability. can do.

In the present invention, it was possible to produce multi-elastic yarns which could be spun from the melt and wound, had a high initial modulus and in which the individual fibrils were not sticking to each other. In the present invention, the yarn is drawn and wound up in a one-step process in an integrated manner, ie directly after spinning using known equipment and no additional processing steps such as relaxation steps are required.

The resulting smooth elastic yarn is suitable for further processing immediately after winding. This elastic thread is braided (umspinne
n) has the advantage over known elastomers that they can be used directly without.

In a preferred example, the polyurethane granules are first melted at 190-240 ° C and extruded. Winding speed is 600m / min or more, preferably 900
Must be faster than m / min, which results in an elongation of 1.5
That's all. Since the drawing and winding take place immediately after the take-off of the spun yarn, the processes can be regarded as occurring at the same time or in synchronism, that is to say as a spin-draw.

The yarn produced is not yet completely cooled on the first roller pair and the actual drawing is still allowed in the drawing zone. This stretching, and thus the larger molecular orientation in the yarn, manifests itself as a low elongation at break, a high boiling shrinkage (Kochschrumpf) and a particularly significantly increased modulus, the molecular orientation in the removal zone being, as expected, influenced by the removal rate, Since the viscosity of is highly temperature dependent, it is significantly affected by the spinning temperature. If the pre-orientation is too small, the modulus cannot rise to the maximum value.

Winding up is preferably carried out without tension.

This high modulus spun drawn yarn can be processed into a flat shape. It is advantageous to carry out a fixing treatment before the finishing, in order to prevent the dimensions of the flat-shaped object from being significantly deformed during the finishing treatment. The elasticity of the product produced can be controlled by choosing fixed conditions.
Since the yarn obtained by the method of the invention is contracted, it is particularly suitable for fixing the shape.

However, this flat shape is up to 130 ° C in water,
It can be tempered preferably at a temperature below the boiling point of water, for example at a temperature of 94-100 ° C.

It is likewise advantageous to condition the drawn elastic yarn before processing to give it the desired elasticity.

Conditioning is preferably performed with steam, hot water or a heated metal surface. To ensure sufficient dimensional stability, temper
It must be done at temperatures above 90 ° C.

Elastic yarns have a modulus of 10 or more before tempering, preferably> 2
0, especially 20 to 40 cN / tex, and the elongation at break is 80 to 300%, preferably 90 to 200%, based on the length of the unstretched yarn. The stretched elastic yarn exhibits completely reversible elasticity until it is stretched to the breaking point.

The elastic yarn of the method of the present invention has 100 to 800%, especially 300% of the length of the unstretched yarn after conditioning, depending on the treating method and treating temperature.
~ 600%, preferably about 400% elongation at break (first
See Table and Table 2).

The elastic yarn spun and drawn by the method of the present invention is advantageous because it exhibits complete reversible elasticity up to the breaking limit.

A preferred field of application of the elastic yarn having rubber-like elasticity obtained by the method of the present invention is a flat-shaped textile. In this case, it has proved to be advantageous to process the elastic yarn obtained by the process according to the invention together with other non-elastic yarns of synthetic or natural fibers into a flat shape with elasticity. It was.

The invention will now be described by way of example with reference to the drawings.

FIG. 1 is a flow sheet of the spinning and drawing method of the present invention, FIG. 2 is a graph of weight-elongation ratio, and FIG. 3 is a hysteresis curve.

In FIG. 1, reference numeral 1 indicates a spinning block having a spinneret. A bundle 2 of fibrils is a refueling pin or roller 3
Are combined into a yarn 2 ', which advances through the roller 4 and the separating roller 4'. The roller 4 and the separating roller 4'form together a roller pair 4,4 '. Another roller pair
5, 5'constitutes a roller 5 and a separating roller 5 '. Reference numeral 6 indicates a reel having a driving roller 7.

In FIG. 2, curve 1 shows the case of cold-spun drawn yarn.
Curves 2 to 4 show the relationship between the weight and the elongation of the same yarn as the yarn of curve 1 tempered at various temperatures. Curve 2 is 40 ° C in water and curve 3 is 60 ° C in water. Curve 4 is for 98 ° C in water.

FIG. 3 shows a hysteresis curve 1 of the spun drawn yarn and a hysteresis curve 2 of the spun drawn yarn further treated at 98 ° C. in water.

The difference in the curves before and after heat treatment makes it clear that greater elasticity occurs at approximately the same maximum load.

The present invention will be described with reference to the following two embodiments.

Example 1 Thermoplastic polyurethane manufactured from aromatic diisocyanate, polycaprolactone macrodiol and butanediol having a hardness (Shore A) of 84 °, a softening point of 185 ° C. and a density of 1.15 g / cm ³ (trade name, manufactured by Goodrich Co., trade name) Name: Estin (Es
10 kg were dried first at 60 ° C. for 8 hours at about 50 mbar and then at 90 ° C. for 24 hours in a high vacuum until the residual water content was 0.01%. When measured with a Ubbelohde viscometer in a mixed solvent of phenol / tetrachloroethane 1: 1 at 0.4% concentration at 25 ° C, the intrinsic viscosity is 1.8.
It was 0.

Tinu made by Ciba Geigy to improve photostability
bottle (Tinuvin, trade name) type UV absorber during polymerization
Granules, or granules can be powdered.
I was able to do it. TiO to improve elasticity and gloss₂And
And SiO₂It was possible to use fillers such as

To produce yarn, the granules are melted in the extruder in the absence of oxygen, for example at 210 ° C., and then 60 bar in a spinning block 1 provided with a 10 μm filter screen, followed by a spinneret with 8 holes. It was pressed into the multi-filament of decitex 41f8 in the spin drawing process. The individual filaments 2 are then cooled in an air blowing chamber (not shown) with a 40 mm water column,
They were put together and refueled by the refueling pin 3. The spinning speed provided by roller 4 was 600 m / min. The yarn 2'is wound around the roller pair 4,4 '5 times and then the second roller pair 5,
It was wound 5 times on 5'and cold-extended to 2.1 times. Normal temperature rollers 4 and 5 having a smooth surface are electric motors (not shown).
And the opposing rollers 4'and 5'were driven by air. The yarn 2'was not pulled because this reduces friction or tension in the yarn. The yarn 2 ″ was wound on the reel by the drive roller 7 at a winding speed of 1250 m / min without tension.

The yarn was manufactured according to the flow sheet of the spinning and drawing method of the present invention shown in FIG.

Example 2 Polyester-based thermoplastic polyurethane having a hardness (Shore A) of 93 °, a softening point of 185 ° C. and a density of 1.19 g / cm ³ and which is also suitable for medical devices (manufactured by Goodrich, trade name: Estin
58277) 10 kg was spun in the same manner as in Example 1 and simultaneously drawn.

The properties of the yarns obtained in Examples 1 and 2 are summarized in Tables 1 and 2.

The yarn 2 ″ of Example 1 obtained by the method of the present invention exhibited the properties shown in column 1 of Table 1. Its strength was 25 cN / tex, its elongation at break was 145%, and its shrinkage by boiling was not found. It was 61% of the length of the stretched yarn.

Further, this yarn was well wound up. This thread showed no tack. From the micrograph of the cross section, it was found that the individual filaments were well separated from each other and had the desired round cross section.

The yarn exhibited the properties shown in columns 2-5 of the table when heat treated, for example in hot water for 2 minutes. In the case of elongation at break in boiling water, the elongation at break increased to 490% (5th
Column). The elastic properties were comparable to commercially available wet spun multi-polyurethane yarns that were tacky to each other.

Examples 3 and 4 10 kg of the thermoplastic polyurethane of Example 1 are 600 m / min or 1600 m / min at different spinning temperatures according to the spinning and drawing method of the present invention.
Spin-stretched at a take-off speed of minutes.

As can be seen from these examples, the possible spinning speeds are strongly dependent on the viscosity of the polymer and thus on the spinning temperature. At relatively high spinning temperatures, as in Example 4, the take-off speed and thus the economics during yarn production is significantly improved.

The spun drawn raw yarn can be drawn together with the polyamide of Decitex 33f10 into a flat shape. After fixing the braid (Gestrick) or after heat treatment, eg dyeing, the product can be processed in a known manner into a flat shape with rubber-like elasticity.

As a special field of use, medical support stockings,
Mention may be made of elastic bandages, sports clothing, swimming pants, pantyhose (fine counts), elastic filters, elastic materials for the garment industry and elastic materials for the production of elastic articles for medical or surgical use, especially artificial prostheses.

DESCRIPTION OF SYMBOLS 1 ... Spinning block, 2 ... Bundle of fibrils 2 '... Unstretched yarn, 2 "... Stretched yarn 3 ... Oiling pin, 4 ... Roller 4' ... Separation roller, 5 ... Roller 5 '... Separation roller, 6 ... Reel 7 ... Reel 6 drive roller

Claims (1)

[Claims] 1. A multifilament elastic yarn produced by irreversibly drawing a thermoplastic polyurethane having a Shore hardness of 80 to 95 ° after melt spinning and cooling, and immediately thereafter winding it at a speed of at least 600 m / min. And has a modulus of 10 to 40 cN / tex, an elongation at break of 80 to 300% with respect to the length of the unstretched yarn, has completely reversible elasticity until reaching the elongation at break, and Polyurethane multi-filament elastic yarn characterized in that the fibrils of are in contact with each other without sticking to each other.