EP0363798B1 - Intermingled sewing-thread consisting of two components, and method for producing the same - Google Patents

Abstract

A two-component loop sewing thread comprising core and effect filaments of high strength and low shrinkage composed of synthetic polymers, with the exception of polyester, is described which has an intrinsic viscosity (measured in solutions in dichloroacetic acid at 25 DEG C) of greater than 0.65 dl/g, having a final strength of over 40 cN/tex, a heat shrinkage at 180 DEG C of less than 8% and a maximum extension under load of less than 18%. This thread has a total denier of 200 to 900 dtex, its core filaments and effect filaments are present in a weight ratio of 95 : 5 to 70 : 30 and the filament titre of the core filaments is 8 to 1.2 dtex and that of the effect filaments 4.5 to 1 dtex.

Description

The present invention relates to a two-component loop sewing thread for modern industrial sewing machines with high strength and low shrinkage and a method for its production.

A similar loop sewing thread is known for example from EP-A 57 583. According to the process described there, several, differently shrinking yarns are fanned by air-jet texturing with different lead and thus a loop yarn is produced. When the shrinkage is triggered in a subsequent fixing process, the loops of the filaments are then tightened into bud-like projections. In an improved embodiment of this known method, which has been described in EP-A 123 479, the yarns are provided with a twist of about 100 to 300 T / m between loop formation and fixation.

A disadvantage of these known methods is that the final strength of the finished loop yarn is lower than would be expected from the strength of the rovings. The final strength of these known sewing threads is only between 25 and 40 cN / tex, whereby final strength here means the quotient of the maximum tensile force and the final titer at the moment of tearing. The filaments of these known yarns can also shrink to different degrees depending on the degree of integration. These differences can be seen in a different coloration along a filament and are particularly pronounced from filament to filament if yarns with different shrinking capacities have been used.

Single-component loop sewing threads are already known, the final strength of which is between 40 and 50 cN / tex. However, these yarns have poor sewing properties due to their low number of loops. Like conventional sewing threads, they are provided with around 600 to 800 T / m and their elongation at break is relatively high at over 18%.

The present invention relates to a two-component loop sewing thread which does not have the disadvantages of the prior art described above.

In the older, not prepublished applications EP-A-295,601 and EP-A-367,938 two-component loop sewing threads are described. Specific publications in which polyesters with an intrinsic viscosity above 0.65 dl / g are used cannot be found in these publications. According to EP-A-295,601, the yarns are produced by blowing together, with a roving being drawn using an unheated pin just before the intermingling. According to the teaching of EP-A-367,938, at least one roving made of yarn material with a specific strength of 60 to about 75 cN / tex is used as the starting material, which is fed directly to the prewirling step without pre-stretching.

The two-component loop sewing thread with high strength and low shrinkage consists of standing and effect filaments made of polyesters with a high degree of condensation and in particular of polyethylene terephthalate and has a final strength, ie a maximum tensile strength, based on the final titer (final titer = filament titer at the moment of the maximum tensile force) , of more than 40 cN / tex, preferably 48 to 60 cN / tex, a thermal shrinkage at 180 ° C. of less than 8%, preferably less than 5%, and a maximum tensile elongation of less than 18%, preferably less than 15%.

Final strength means the quotient of maximum tensile force and final titer at the moment of tearing; the maximum tensile strength stretch is the elongation that the yarn experiences under the effect of the maximum tensile force.

The total titer of the two-component loop sewing thread according to the invention is generally 200 to 900 dtex. Underneath and overlying titers can also be produced if they are of interest in the individual application, but they are not the rule. As already stated, the two-component loop sewing thread according to the invention is composed of stand-up filaments and effect filaments. The upright filaments are in the Oriented to a much greater extent in the direction of the fiber axis than the effect filaments, which are interwoven and intertwined with the upright filaments, but additionally form loops protruding from the fiber structure due to their greater length and thus have a significant influence on the textile and usage properties of the yarn according to the invention. The total titers of upright filaments and effect filaments of the loop sewing thread according to the invention are in a ratio of 95: 5 to 70:30, preferably 90:10 to 80:20.

Stand-up filaments and effect filaments differ in terms of their individual titer. This is 8 to 1.2, preferably 5 to 1.5 dtex for the standing filaments, and 4.5 to 1, preferably 3 to 1.4 dtex for the effect filaments. Within these titer limits, the single titer of the standing filaments is 1.2 to 6 times, in particular 1.5 to 3.5 times, the single titer of the effect filaments.

In principle, the two-component loop sewing threads according to the invention can be produced from synthetic spinnable polymers and polycondensation products, such as polyamides, polyacrylonitrile, polypropylene and polyesters. The use of polyesters as starting material for the production of the yarns according to the invention is particularly expedient. Suitable polyesters are in particular those which essentially consist of aromatic dicarboxylic acids, such as, for. B. terephthalic acid or isophthalic acid, 1,4-, 1,5- or 2,6-naphthalenedicarboxylic acid, hydroxycarboxylic acids such as. B. para- (2-hydroxyethyl) benzoic acid and aliphatic diols with 2 to 6, preferably 2 to 4 carbon atoms such as. B. ethylene glycol, 1,3-propanediol or 1,4-butanediol can be obtained by cocondensation. These polyester raw materials can also by condensing smaller proportions of aliphatic dicarboxylic acids such. B. glutaric acid, adipic acid or sebacic acid or of polyglycols such as. B. diethylene glycol (2,2-dihydroxydiethyl ether), triethylene glycol (1,2-di (2-hydroxy-ethoxy) ethane) or modified by smaller proportions of higher molecular weight polyethylene glycols. A further modification possibility, which in particular influences the dyeing behavior of the two-component loop sewing threads according to the invention, is the modification by building blocks containing sulfo groups such as e.g. B. by the incorporation of sulfoisophthalic acid.

The upper limit of the final strength of the loop sewing threads obtainable according to the invention depends on the selected degree of condensation of the polymer material used, in particular the polyester material. The degree of condensation of the polyester is expressed in its viscosity. A high degree of condensation, i.e. H. a high viscosity leads to particularly high final strengths of the yarns according to the invention. Preference is therefore given to producing loop sewing threads according to the invention with high molecular weight polyesters with an intrinsic viscosity (IV) of over 0.65 dl / g, in particular over 0.75 dl / g, these values being measured in solutions in dichloroacetic acid (DCE) at 25 ° C.

A preferred polyester material for producing the loop yarns according to the invention is polyethylene terephthalate.

The two-component loop sewing thread according to the invention, consisting of upright and effect filaments, is produced by air-jet texturing of two roving strands fed with different lead, these roving strands having different total and individual titer, but both consisting of high-strength, low-shrinkage and low-stretch filaments.

High-strength, low-shrinkage and low-stretch filaments are understood to mean those which have a maximum tensile strength, based on the final titer, of at least 65 cN / tex, generally 65 to 90 cN / tex, preferably 70 to 84 cN / tex, a maximum tensile strength Elongation of at least 8%, usually 8 to 15%, preferably 8.5 to 12%, and a thermal shrinkage at 180 ° C. of at most 9%, usually 5 to 9%, preferably 6 to 8% .

In the air nozzle texturing of yarns, it is known that the filament material is fed to the blow nozzle at a higher speed than is drawn from it. The excess speed of the feed compared to the take-off, expressed as a percentage based on the take-off speed, is referred to as the advance. In the method according to the invention, the two strands of yarn to be mixed, which then deliver the stand or the effect filaments in the finished yarn, are fed to the texturing nozzle with different lead. The roving strand, from which the upright filaments of the yarn according to the invention emerge, is fed to the blowing nozzle with a lead of 3 to 10%, the roving strand, from which the effect filaments of the yarn according to the invention emerge, with a lead of 10 to 60%. Because of this different advance, longer lengths of the effect filaments are swirled with smaller lengths of the upright filaments in the texturing nozzle, which means that the effect filaments in the finished yarn according to the invention form considerably more arches and loops than the upright filaments, which run essentially in the direction of the fiber axis.

The total titers of the roving strands forming the upright filaments and the effect filaments are selected so that they have a ratio of 95: 5 to 70:30, preferably 90: 10 to 80:20, and that their mixture after the interlacing is 200 to 900 dtex.

worin T_St und V_St die Titer und Voreilung des Stehervorgarns und T_E und V_E die Titer und die Voreilung des Effektvorgarns bedeutet.It should be noted that the total titer T _S of the intermingled yarn is not simply composed of the titers of the roving, but that the leading of the two roving must be taken into account here. The total titer T _S results from the following formula

where T _St and V _{St are} the titer and lead of the roving and T _E and V _{E are} the titer and the lead of the effect roving.

The individual titer of the filament of the roving is 8 to 1.2, preferably 5 to 1.5 dtex, the individual titer of the filament of the effect roving is 4.5 to 1, preferably 3 to 1.4 dtex. Within the framework of these values, the individual titer of the rovings is selected so that the individual titer of the upright filaments is 1.2 to 6 times, preferably 1.5 to 3.5 times, the individual titer of the effect filaments.

As rovings for the production of the two-component loop sewing thread according to the invention, the high-strength and low-shrinkage yarns can be used, the z. B. from DE-AS 12 88 734 or EP-A 173 200 are known and their production is described there. The rovings required for the process according to the invention are produced in an integrated process step immediately preceding the air turbulence, in which they are obtained by stretching a partially oriented spun fabric and an immediately subsequent, essentially shrink-free heat treatment. Substantially shrink-free means that the yarns are preferably kept at a constant length during the heat treatment, but that a shrinkage of up to 4%, better not over 2%, can be admitted. The method according to the invention therefore comprises the drawing of two partially oriented yarns with different total and single filament titers on separate drawing devices, an essentially shrink-free heat treatment and an immediately subsequent feed for air jet texturing. The partially oriented yarns are drawn at a temperature of 70 to 100 ° C., preferably via heated godets, at a drawing tension in the range from 10 to 25 cN / tex, preferably from 12 to 17 cN / tex (in each case based on the drawn titer). The essentially shrink-free heat treatment of the yarns immediately after stretching takes place at a yarn tension between 2 and 20 cN / tex, preferably at 4 to 17 cN / tex, and a temperature in the range from 180 to 250 ° C., preferably from 225 to 235 ° C. In principle, this heat treatment can be carried out in any known manner; it is particularly expedient to carry out the heat treatment directly on a heated extraction godet.

When the method according to the invention is carried out, the drawing conditions of the two partially oriented yarns are preferably kept as identical as possible. However, differences in the drawing conditions of up to ± 10% can be tolerated.

If desired, the loop yarn withdrawn from the air texturing nozzle can still be subjected to a fixing process. This fixation can also be carried out in any manner known per se, it is expedient to subject the yarn of constant length to hot air treatment at temperatures of 200 to 320 ° C., preferably 240 to 300 ° C.

The two-component loop sewing thread according to the invention thus obtained surprisingly shows several advantages over known sewing threads:

The loops of the individual filaments remain fully intact and, thanks to the entrained air, result in good sewing properties even at high sewing speeds. This advantage is evident in the high values for the so-called sewing length to break, which are determined by the method known from DE-A-34 31 832. The uniformly stretched filaments lead to uniform coloring and thus to a calm image of the seam. The strength of the yarns produced in this way is significantly higher than that of sewing threads with differently shrinking filaments.

The use of similar rovings also simplifies the manufacturing process. When using shrinking rovings, for example, much more loops must first be produced than the finished sewing thread should have, since the shrinking process leads to a reduction in the number of loops. The two-component loop sewing thread according to the invention does not have to be twisted during its manufacture. It is therefore untwisted and can also be used untwisted as a sewing thread. Mostly, however, is subsequently in the course of further processing, eg. B. for optical reasons, a relatively weak rotation of about 100 to 300 T / m applied.

Example:

A device for producing the two-component loop sewing thread according to the invention can be constructed, for example, from the following elements: a bobbin creel for the bobbins of the main and effect roving, two drafting units working in parallel with heatable inlet and outlet godets, a blowing nozzle with separate infeed units for the exact setting of the advance of the roving strands, a take-off unit for the defined take-off of the blown yarn, if desired a conventional hot air fixing device and a take-up reel.

A bobbin with stand roving with a titer of 380 dtex f40 (single filament titer: 9.5 dtex) and a bobbin with effect roving with a titer of 83 dtex f24 (single filament titer: 3.5 dtex) are placed on the creel. Both rovings consist of polyethylene terephthalate with an intrinsic viscosity of 0.68 dl / g, measured in DCE at 25 ° C.

The two rovings are fed to the drawing units assigned to them and drawn there at a temperature of the inlet godet of 90 ° C. in a ratio of 1: 2. The draw tension was 15 cN / tex for the main roving and 14 cN / tex for the effect roving. The drawn yarns were passed in 10 turns around the outlet godets of the drafting systems, which were heated to 230 ° C. The yarn running speed for the two drafting units was adjusted separately so that the running speed into the blowing nozzle was 315 m / min for the main roving and 420 m / min for the effect roving. The blown yarn was drawn off behind the blow nozzle at 300 m / min. This results in an advance of 5% (tradition 1.05) for the main yarn and 40% (tradition 1.40) for the fancy yarn.

After leaving the blow nozzle, the loop yarn was fixed by passing it through a 160 cm long hot air oven heated to 240 ° C.

The raw yarn thus obtained was wound up. It has a titer of 243 dtex / f64, a final strength of 50.7 cN / tex, a maximum tensile strength elongation of 9.8% and a heat shrinkage at 180 ° C of 3.1%.

After dyeing the raw yarn, the following characteristics result; Titer 255 dex / f64, final strength 48 cN / tex, maximum tensile elongation 13.2% and heat shrinkage at 180 ° C 0.7%.

In the sewing test, its average sewing length is greater than 4,000 stitches when sewing forward and greater than 2,000 stitches when sewing backward.

The yarns according to the invention indicated in the following table can be produced in an analogous manner.

Claims (15)

1. A two-component loop sewing yarn composed of core and effect filaments of high tenacity and low shrinkage and made of a polyester which has an intrinsic viscosity (measured in solutions in dichloroacetic acid at 25°C) of more than 0.65 dl/g, which yarn has an ultimate tenacity of above 40 cN/tex, a thermoshrinkage at 180°C of below 8% and an ultimate tensile strength elongation of below 18%.
2. A two-component loop sewing yarn as claimed in claim 1, having a total linear density of 200 to 900 dtex.
3. A two-component loop sewing yarn as claimed in at least one of claims 1 and 2, wherein the total linear densities of the core filaments and effect filaments are in a ratio of 95 : 5 to 70 : 30.
4. A two-component loop sewing yarn as claimed in at least one of claims 1 to 3, wherein the linear density of the core filament is 8 to 1.2 dtex and the linear density of the effect filament is 4.5 to 1 dtex, the linear density of the core filaments being 1.2 to 6 times the linear density of the effect filaments.
5. A two-component loop sewing yarn as claimed in at least one of claims 1 to 4, wherein the core and effect filaments are composed of polyethylene terephthalate.
6. A two-component loop sewing yarn as claimed in at least one of claims 1 to 5, wherein the polyester has an intrinsic viscosity of greater than 0.75 dl/g.
7. A two-component loop sewing yarn as claimed in at least one of claims 1 to 6, having an ultimate tensile strength elongation of below 15%.
8. A process for manufacturing a two-component loop sewing yarn that is composed of core and effect filaments and has an ultimate tenacity of above 40 cN/tex, a thermoshrinkage at 180°C of below 8% and an ultimate tensile strength elongation of below 18%, wherein the core and effect filaments are intermingled with one another by air jet texturing two feed yarn strands supplied to the texturing jet at different speeds, wherein the feed yarn strands used have different total and filament linear densities but both consist of filaments of synthetic polymers which have an ultimate tensile strength, in terms of the ultimate linear density, of at least 65 cN/tex, a thermoshrinkage at 180°C of at most 9% and an ultimate tensile strength elongation of at least 8%, and wherein the filaments of the feed yarn strands are obtained by subjecting a partially oriented yarn material to a drawing operation immediately upstream of the air jet intermingling and by subjecting the drawn material immediately thereafter to a heat treatment in which a shrinkage of up to 4% can be allowed, but preferably no shrinkage takes place.
9. The process as claimed in claim 8, wherein the core filaments are fed into the texturing jet at an overfeed of 3 to 10% and the effect filaments are fed into the texturing jet at an overfeed of 10 to 60%.
10. The process as claimed in at least one of claims 8 and 9, wherein the total linear densities of core and effect yarn strands are in the ratio of 95 : 5 to 70 : 30 and are chosen in such a way that, if the overfeed is taken into account, the total is 200 to 900 dtex.
11. The process as claimed in at least one of claims 8 to 10, wherein the linear density of the core filaments fed into the texturing jet is 8 to 1.2 dtex and the linear density of the effect filaments fed into the texturing jet is 4.5 to 1 dtex, the linear density of the core filament being 1.2 to 6 times the linear density of the effect filament.
12. The process as claimed in at least one of claims 8 to 11, wherein the drawing conditions for core and effect filaments are the same or differ by up to ± 10%.
13. The process as claimed in at least one of claims 8 to 12, wherein the drawing is carried out at 70 to 100°C under a drawing tension of 10 to 25 cN/tex, based on the drawn linear density.
14. The process as claimed in at least one of claims 8 to 13, wherein the heat treatment carried out immediately after the drawing is carried out at a yarn tension of 2 to 20 cN/tex and at a temperature of 180 to 250°C.
15. The process as claimed in at least one of claims 8 to 14, wherein the yarn emerging from the texturing jet is set in a conventional manner at a temperature of 200 to 320°C.