EP0530860B1 - Interminded 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 nozzle 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 approximately 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.

One-component loop sewing threads are already known, the final strength of which is between 40 and 50 cN / tex. But these yarns show bad 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.

Two-component loop sewing threads are described in the older, not prepublished applications EP-A 295 601 and EP-A 367 938. Specific publications of these sewing threads with maximum tensile strength strains below 18% cannot be found in these publications. According to EP-A 295 601, the yarns are produced by blowing, with at least the upright roving being stretched using an unheated pin with a diameter of less than 10 mm immediately 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 intermingling step without pre-stretching.

The two-component loop sewing thread according to the invention with high strength, low shrinkage and low maximum tensile elongation consists of upright and effect filaments made of synthetic polymers such as e.g. Polyamides, polyacrylonitrile, polypropylene, but preferably polyesters and especially polyethylene terephthalate and has a final strength, i. H. a maximum tensile strength, based on the final titer (final titer = filament titer at the moment of the maximum tensile force), of over 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%.

The final strength is understood to be the quotient of maximum tensile force and final titer at the moment of tearing; the maximum tensile strength is Elongation experienced by the yarn when subjected to 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, provided 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 oriented on average 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 the textile and usage properties of the yarn according to the invention are essential participate. 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 the above-mentioned 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, for. 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 diethylene glycol (2,2-dihydroxydiethyl ether), triethylene glycol (1,2-di (2-hydroxy-ethoxy) ethane) or also from smaller proportions of higher molecular weight polyethylene glycols can be modified. 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 thread 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. H. a high viscosity leads to particularly high final strengths of the yarns produced according to the invention. High-molecular-weight polyesters with an intrinsic viscosity (IV) of more than 0.65 dl / g, in particular more than 0.75 dl / g, are therefore preferred for the production of the loop sewing threads according to the invention, these values being measured in solutions in dichloroacetic acid (DCE) at 25 ° C. Loop sewing threads with the property profile defined above and based on polyesters with IV values above 0.65 dl / g are the subject of EP-B 363 798 and excluded from the subject of the present application.

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

The inventive production of the two-component loop sewing thread, consisting of stand and effect filaments, is carried out by air nozzle texturing two roving strands fed with different lead, these roving strands have different total and individual titers, but both consist of high-strength, low-shrinkage and low-stretch filaments.

High-strength, low-shrinkage and low-elongation 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 blowing 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 effect filaments in the finished yarn, are fed to the texturing nozzle with different lead. The roving strand, from which the stand-up 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 $${\text{T}}_{\text{S}}{\text{= T}}_{\text{St}}{\text{· (1 + V}}_{\text{St}}{\text{/ 100) + T}}_{\text{E}}{\text{· (1 + V}}_{\text{E}}\text{/ 100)}$$

where T _St and V _{St are} the titer and advance of the roving and T _E and V _{E are} the titer and the advance 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, which, for. B. from DE-AS 12 88 734 or EP-A 173 200 are known and their production is described there. The production of the rovings required for the process according to the invention 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 is the subject of EP-B 363 798 and of the subject of present registration excluded.

In a preferred embodiment of the method according to the invention, 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 take-off godet.

Substantially shrink-free means that the yarns are preferably kept at a constant length during the heat treatment, but that shrinkage of up to 4%, better not more than 2%, can be permitted.

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, provide good sewing properties even at high sewing speeds. This advantage is evident in the high values for the so-called sewing length up to breakage, which is that according to DE-A-34 31 832 known methods can be determined. The uniformly stretched filaments lead to even 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, many more loops must first be produced than the finished sewing thread should then 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.

Claims (10)

1. A high strength, low shrinkage two-component loop sewing yarn composed of core and effect filaments made of synthetic polymers from which polyester having an intrinsic viscosity (measured in solutions in dichloroacetic acid at 25°C) of greater than 0.65 dl/g shall be excepted and having an ultimate tenacity, expressed as the ratio of the ultimate tensile strength to the ultimate linear density at the moment of action of the ultimate tensile strength, 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, characterized in that its ultimate tensile strength elongation is less than 15%.
3. A two-component loop sewing yarn as claimed in at least one of claims 1 and 2, characterized in that its linear density is 200 to 900 dtex.
4. A two-component loop sewing yarn as claimed in at least one of claims 1 to 3, characterized in that the total linear densities of the core and effect filaments are in a ratio of 95 : 5 to 70 : 30.
5. A two-component loop sewing yarn as claimed in at least one of claims 1 to 4, characterized in that the core filament linear density is 8 to 1.2 dtex and the effect filament linear density is 4.5 to 1 dtex and in that the core filament linear density is 1.2 to 6 times the effect filament linear density.
6. A two-component loop sewing yarn as claimed in at least one of claims 1 to 5, characterized in that core and effect filaments are composed of a polyester.
7. A two-component loop sewing yarn as claimed in claim 6, characterized in that the polyester is polyethylene terephthalate.
8. A process for manufacturing a two-component loop sewing yarn as claimed in claim 1, composed of core and effect filaments, which has an ultimate tenacity, expressed as the ratio of the ultimate tensile strength to the ultimate linear density at the moment of action of the ultimate tensile strength, of above 40 cN/tex, a thermoshrinkage at 180°C of below 8% and an ultimate tensile strength elongation of below 18%, which comprises interlacing the core and effect filaments by air jet texturing two feed yarn strands fed two the texturing jet at different rates of speed, which feed yarn strands have different strand and filament linear densities but both consist of filaments of synthetic polymers having an ultimate tenacity of at least 65 cN/tex, a thermoshrinkage at 180°C of 5 to 9% and an ultimate tensile strength elongation of at least 8%, excluding a process where the filaments of the feed yarn strands are obtained by a stretch-drawing of a partially oriented material immediately prior to the air interlacing and an immediately subsequent heat treatment where a shrinkage of up to 4% may be allowed and further excluding a process where the strech-drawing of the core feed yarn strand is effected using an unheated pin having a diameter of less than 10 mm.
9. The process as claimed in claim 8, characterized in that both feed yarn strands consist of filaments of synthetic polymers having an ultimate tenacity of 70 to 84 cN/tex, a thermoshrinkage at 180°C of 6 to 8% and an ultimate tensile strength elongation of 8.5 to 12%.
10. The process as claimed in at least one of claims 8 and 9, characterized in that 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%.