DE2153945B2 - POLYESTER WIRE FOR THE PRODUCTION OF ZIPS - Google Patents

Description

Orientation angle = 8 (4 J - 1)

applies, whereby the equation is to be regarded as fulfilled, when the measured angle from the value given by the equation is not more than 2 ° deviates upwards or downwards, the mean crystallite width in the direction transverse to the wire 80 bis 200A and the mean fluctuation of the crystallite size in the direction of the wire, given numerically achieved through the half-width of the small-angle X-ray reflex, a maximum of 0.40 °.

The invention relates to the use of certain polyester monofilaments for the production of dimensionally stable zippers.

As is known, polyesters can be spun into threads or wires by means of spinning units through fine nozzles. Here z. For example, the wires are spun in a hot water bath and then pulled out to several times their original length in order to improve the mechanical and textile-technical properties. To achieve the best possible properties, stretching takes place in a certain ratio (approximately 1: 3 to 1: 6) and in a more or less narrowly delimited temperature range (between 80 and 220 ^° C.). Threads are mostly drawn on heated plates or hot godets, while it is preferred to draw the wires in hot water because of the better heat transfer. The monofilaments produced in this way have average strengths of 20 to 40 Rkm at 15 to 30% elongation, depending on the stretching ratio. In order to reduce the high boiling shrinkage (measured after 10 minutes in boiling water) of about 10% of these wires, they are then fixed either in hot water, on a heated godet or in hot air. This can be done both under tension and without tension.

The monofilaments obtained can be used in various fields, such as manufacturing of ropes and ropes, of filters and sieves or of zippers.

In the zipper sector, however, it has been shown that monofilaments with the above-mentioned average Properties can only be used to a limited extent, because in the end it is a question of strength and elongation does not really matter, but that other criteria are decisive.

There was therefore the task of making monofilaments from polyethyleneterephthalate to make available, which is particularly good for the production of dimensionally stable Zippers are suitable.

According to the invention, this object is achieved by using polyethylene terephthalate monofilaments, which have an intrinsic viscosity / from 0.80 to 1 07, at which the orientation angle the crystallites within the monofilament are between 17 and 26 °, with the intrinsic viscosity / and the orientation angle of the crystallites the ίο numerical relationship

Orientation angle = 8 (4 J - 1)

applies, whereby the equation is to be regarded as fulfilled if the measured angle does not deviate more than 2 ° upwards or downwards from the value specified by the equation, the mean crystallite width in the direction across the wire is 80 to 200 A and the mean fluctuation of the Crystallite size ao in the direction of the wire, indicated numerically by the half-width of the small-angle X-ray reflection, reached a maximum of 0.40 °.

It has thus been found that for problem-free processing of polyethylene terephthalate wires too he zippers have the following characteristics:

1. The molecular weight for which the basic viscosity or intrinsic viscosity / is a measure (determination of the intrinsic viscosity cf. WN Dawydoff: "Determination of the molecular weight of polyamides", VEB Verlag Technik Berlin, 1959, p. 44). Monofilaments with an intrinsic viscosity J = 0.80 to 1.07, preferably 0.82 to 0.92, can best be processed in zippers.

2. The orientation of the crystals in the direction of the wire axis, determined from wide-angle X-ray examinations and given in degrees, must be between 17 and 26 °.
There is a numerical relationship between the intrinsic viscosity and the orientation angle. Only those polyester monofilaments can be easily processed into zippers for which the following applies:

⁴ S orientation angle = 8 (4 / - 1),

where the equation is considered to be satisfied if the measured angle differs from that given by the The value specified in the equation does not deviate by more than 2 ° upwards or downwards.

3. The mean crystallite width in the direction across the wire is 80 to 200 A.

4. The mean variation in crystallite size in the direction of the wire, numerically indicated by the half-value width of the small-angle X-ray reflex may not exceed 0.40 °.

The crystallite orientation is determined from wide-angle X-ray measurements. For this purpose, the azimuthal intensity distribution of the (OlO) reflection is measured (2 θ = 17.5 °) on a commercial Zählrohrgoniometer. After separating the scattering background of the bell curve by a straight line, the width of the distribution curve is determined at half the maximum intensity and converted into degrees (see L. A1 e χ a η der, "X-Ray Diffraction Methods in Polymer Science", J. Wiley & Sons , Inc., New York, 1969, pp. 198 to 279).

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The mean width of the crystallites in the direction across the wire is also derived from a wide-angle gonioineter curve calculated (cf. H. Klug, L. Alexander, "X-Ray Diffraction Procedures", publisher J. Wiley & Sons, Inc., New York, 1954, pp. 491 to 538). The crystallite width is determined according to the equation

Crystallite width =

0.01745 (D * - py * - cos 8.75 °

where W is the wavelength (A) of the X-ray radiation used, D (degrees) is the width at half the reflection height and / (degrees) is the reflection width at half the height of a reflection of a metallic silicon standard (reflection broadening by the instrument). The most favorable reflex for polyester is the (OlO) reflex, the radial half-width of which is determined using the conventional method.

A measure of the variation in the center of gravity of the crystalline areas in the direction of the wire is given by the half-width of the X-ray small-angle meridian reflex. To determine this A Kratky chamber was used for half-value ranges (cf. H. N e f f, »Fundamentals and Application der X-ray fine structure analysis ", Verlag R. Oldenbourg, Munich, 1959, pp. 321 to 325). to For this purpose, the subsurface below the scattering maximum was separated by a straight line that took the Intensities at 2 0 = 0.35 ° and 20 = 1.25 ° connects. The remaining peak became again the reflex width measured at half maximum intensity.

Polyethylene terephthalate monofilaments can be Process into dimensionally stable zippers if they have the features according to the invention. The advantages resulting therefrom are explained in more detail below.

The production of zippers from synthetic monofilaments has been known for a long time. Included the wires are pressed or spread wide at a certain distance by a stamping device. The wire can now z. B. in a piece of tissue be woven in. Two pieces of fabric with terminal broadly embossed monofilaments can now are hooked into one another by means of a slider, so that a zipper is present. Of the Wire with the heads impressed at a certain distance can also be formed into a helix. Two of these spirals are now hooked into one another in such a way that they are removed from the embossed heads be held together.

If you now process polyester monofilaments which do not have the features according to the invention required above have to zip fasteners, the following difficulties arise: When embossing the cam experiences the wire exerts a very large transverse load and bursts open.

Zippers with burst embossing points are of course unusable. This is avoided by using a polyethylene terephthalate with an In-Irinsic viscosity J of 0.80 to 1.07, preferably 0.82 to 0.92. This means that the transverse strength increases with increasing molecular weight, because the long chain molecules, with increasing intrinsic viscosity, are more difficult to align when stretching in the longitudinal direction of the wire. Some of them are still at right angles to the 945 2

Monofilament longitudinal axis and make an increasing contribution to transverse strength with increasing molecular weight.

This is also indicated by the orientation of the crystals, measured in degrees of angle, in the wire. A large Angle at high intrinsic viscosity means that fewer crystallites lie in the longitudinal direction, while with a low molecular weight, a relatively small angle results, which points to a stronger preferred orientation of crystallites in the longitudinal direction.

It has also been shown that zip fasteners made from polyester wires have an intrinsic viscosity from 0.80 to 1.07, preferably 0.82 to 0.92, are particularly flexible, pliable and dimensionally stable, if in the case of the monofilaments the average width of the crystallites in the direction across the wire is 80 to 200 Å and the mean fluctuation of the crystallite size in the wire direction, expressed numerically by the half-width of the x-ray small whorl reflex, not exceeding 0.40 °.

Zip fasteners made from such polyester wires show their flexibility and suppleness in that they immediately spring back into their original position when they are subjected to bending. The dimensional instability can be checked by a test in boiling water. The zipper is placed in boiling water for 10 minutes and the shrinkage, expressed as a percentage, is then measured. Usable zippers may be less than; Shrink 1%; because the zippers with a heat shrinkage greater than 1 ⁰ Zo decrease in size. B. after dyeing, after a hot wash or after ironing, the flattened cams, so that the zipper is hardly caught and bursts at the slightest stress. In addition, the garment into which the zipper is sewn wrinkles after this thermal treatment because the zipper has become shorter.

example 1

A polyethylene terephthalate with a melting point of 256 ° C and an intrinsic viscosity of 0.85 is spun into a wire using a melt extruder. Subsequently, in a hot 95 ° C water bath stretched 4.6 times its original length. A fixation then follows in hot air, whereby the monofilaments can shrink. They show the following properties (diameter 0.50 cm):

Intrinsic viscosity 0.85

Crystalline orientation angle 20.00 °

Average crystallite width 86 A

Crystallite size 0.36 °

A monofilament with these characteristics can easily be processed into a zipper, the is completely dimensionally stable. Boiling shrinkage after 10 min in boiling water < 1%>. If, on the other hand, a polyethylene terephthalate is used with a Intrinsic viscosity of 0.65, a crystallization angle of 13.4 ° is measured, a value that purely arithmetically through the formula found

Orientation angle = 8 (4 / - 1),
Orientation angle for intrinsic viscosity
= 0.65 ■ = 12.8 °

is confirmed. This angle is smaller than claimed according to the invention. Although the mean crystallite width 89 A and the crystallite size is 0.39 °, can be made of polyethylene terephthalate Mcnofilen Do not produce zippers with these properties because the wires are constantly being processed burst open. 30 cracks were counted at 100 embossing points. Summarized here again the properties of these bad monofilaments:

Intrinsic viscosity 0.65

Crystalline orientation angle 13.40 °

Average crystallite width 89A

Crystallite size 0.39 °

If you want a polyethylene terephthalate with an intrinsic viscosity greater than 1.07, e.g. B. 1.10, spin, this can no longer be processed into D-seams because of its high viscosity.

Example 2

A polyethylene terephthalate with a melting point of 256 ° C and an intrinsic viscosity of 0.90 is spun on a melt extruder. Then in a hot water bath of 95 ° C stretched to 4.8 times the original length. This is followed by a fixation in hot air, whereby the wire can shrink.

The following properties were measured:

Intrinsic viscosity 0.90

Crystalline orientation angle 20.60 °

Average crystallite width 98A

X-crystallite size 0.35 °

A wire with these properties can be processed into a zipper without any problems. He shows no cracks, is very soft and pliable and shows after a residence time of 10 minutes in boiling water a shrinkage of <C 1%.

If, on the other hand, polyethylene terephthalate wires are used, which have an intrinsic viscosity of 0.90 own, but the claimed ones due to poor spinning or improper post-treatment Do not have properties, the result is zippers that are not dimensionally stable.

There were z. B. measured the following properties:

Intrinsic viscosity 0.90

Crystalline orientation angle 29.20 °

Average crystallite width 47 A

Crystallite size 0.50 °

You can see that the formula we found Orientation angle = 8 (4 · J - 1)

is not fulfilled, because then a crystallite orientation angle of 20.8 ^{c should} result. In addition, the mean crystallite width of 47 Å is too small and the mean fluctuation in the crystallite size, indicated numerically by the half-width of the small-angle X-ray reflection, is too large at 0.50 °.
A zip fastener made from these monofilaments shows a boiling water shrinkage of 5% after 10 minutes. The zipper proves to be unusable because the cams only partially get caught when they are closed and then burst open at the slightest tensile stress.

Claims (1)

21 53 845 Claim: Use of monofilaments made of polyethylene terephthalate for the production of zip fasteners, characterized in that the polyethylene terephthalaimonofii has an intrinsic viscosity J of 0.80 to 1.07, the orientation angle of the crystallites within the monofilament is between 17 and 26 °, between the intrinsic viscosity / and the orientation angle of the crystallites the numerical relationship