EP1036866B1 - Sewing thread and method for the production of a sewing thread - Google Patents

Abstract

A sewing yarn has a core-sheath structure, whereby the yarn spun around the multi-filament core contains fewer than an average of 41 individual fibers. Sewing yarn (I) is prepared from two component yarns (II) by twisting them together, whereby each component yarn has a core thread construction, comprising (A) a multifilament yarn core and (B) a second yarn that is spun around the core, whereby at least one of the component yarns contains fewer than 41 individual fibers. An Independent claim is included for a process for the production of (I) whereby the roving of each component yarn is compressed immediately prior to spinning with the multi-filament core, such that at least one component yarn in the finished yarn (I) contains fewer than 41, preferably 20-38 individual fibers.

Description

The present invention relates to a sewing yarn having the features of the preamble of patent claim 1 and to a method for producing such a sewing yarn having the features of the preamble of patent claim 19.

Sewing threads are known in various constructions, whether as sewing threads, as air-twisted yarns or as core yarns, each of the constructions mentioned above having their individual advantages or weaknesses.

Sewing threads, which are designed as core yarns, have at least two rovings, wherein these at least two rovings designed as core yarns are processed by twisting into finished sewing thread. Each of these rovings has the construction of a core yarn, such that each roving at least one core of a first multifilament yarn component which core is then wound with a second fiber yarn component. In other words, such a roving thus has a core-shell structure, wherein the core through the inner multifilament core, which is also referred to as the first yarn component, and the sheath by a fiber yarn, which spins around the soul and the second hereinafter Yarn component or as a second fiber yarn component is formed is formed.

Since the second fiber yarn component or the sheath component in such known core yarns is intended to cover the first multifilament yarn component so as to protect this first multifilament yarn component, which provides a major part of the strength of the finished sewing yarn, from undesirable damage during sewing, the art has held To date, it is necessary for such a fiber yarn wrap to be so dense that the sewing yarn produced from two rovings has at least about 45 individual fibers per roving, but generally between 50 and 88 individual fibers per roving. However, this means that such Coregarne are relatively expensive to produce due to the relatively high use of Fasergarnmenge.

The present invention has for its object to provide a sewing thread of the specified type, which has the construction of a core yarn and cheaper than previously produced.

This object is achieved by a sewing yarn with the characterizing features of claim 1.

The sewing thread according to the invention likewise consists, like the known sewing thread described above, of at least two rovings which are twisted together to form the sewing thread. Each roving hereby has the construction of a core yarn, this core yarn comprising at least one first multifilament yarn component forming the core and a second fiber yarn component surrounding the core. In the sewing thread according to the invention seen in the cross section of the finished sewing yarn, the fiber yarn wrapping of at least one roving a maximum of 41 individual fibers, preferably less than 41 individual fibers, so that accordingly compared to the previously described prior art, the sewing yarn according to the invention a substantially smaller number of fiber yarns in has the coat of rovings forming fiber yarn wrapping. In other words, therefore, the sewing thread according to the invention differs from the conventional sewing thread in that the sewing thread according to the invention has at least one roving in which the fiber yarn wrapping has decidedly fewer individual fibers than is the case in the prior art.

Surprisingly, it has been found that, despite the reduced number of individual fibers in the fiber yarn wrapping of the roving yarn or of the rovings, the sewing yarn according to the invention still has improved sewing properties in comparison to an otherwise identical conventional sewing yarn. This is the more astonishing since the experts have assumed the minimum of individual fibers of at least 45 individual fibers per roving mentioned before in the prior art as the lowest value in order to ensure adequate coverage and adequate protection of the multifilament yarn component forming the core of the roving. The improved sewing performance of the sewing yarn according to the invention, which expresses up to 15% higher sewing speeds or 20% longer seams in multidirectional sewing and a higher number of created with the sewing thread buttonholes according to the invention without thread breakage, is attributed to the fact that provided in the sewing thread according to the invention Fiber yarn wrapping of the roving yarn with a maximum of 41 individual fibers or preferably less (seen over the cross section of the finished sewing yarn) on the one hand still protects the multifilament core of each roving adequately against mechanical and / or thermal damage and on the other hand has increased structuring due to the reduced number of individual fibers in the roving , so that even more air is entrained by such reduced with respect to the individual fiber strand wrapping, thereby od an improved cooling of heated by industrial sewing Fadenleitorgane he is brought to the needle. Also, by reducing the individual fibers in the fiber yarn wrapping, the hairiness is reduced and further minimizes the risk that sticking ends of individual fibers in the needle or on the Fadenleitorganen get caught and thus cause a thread break when sewing. Furthermore, the sewing thread according to the invention has due to the reduction of the individual fibers in the fiber yarn wrapping of at least one roving yarn, compared to a conventional sewing thread, which has at least 45 individual fibers in the Faserergarnumspinnung, yet significantly reduced thickness, so that even finer seams can be created with the sewing thread according to the invention, which previously remained closed to the conventional core yarn. Due to the fact that the sewing thread according to the invention also requires a reduced use of material because of the reduced number of individual fibers in the fiber yarn wrapping, the sewing thread according to the invention can be produced correspondingly less costly in comparison with a conventional core yarn. This advantage is further emphasized in the sewing thread according to the invention characterized in that during the wrapping of the roving a small amount of fiber yarn must be processed, so that accordingly the production speeds of the sewing yarn according to the invention compared to the manufacturing process of conventional sewing thread accordingly, preferably by 5% to about 15%, can be increased.

In order to reproducibly and unambiguously measure the number of individual fibers which are provided in the fiber yarn wrapping of the at least one roving yarn, five cross sections are made over a length of 2 m of the finished sewing yarn, so that the fiber yarn batting with reference to these cross sections their individual fiber number can be counted microscopically. This process is then repeated four times after each unwinding of 50 m, so that then 25 cross-sections are correspondingly evaluated microscopically, from which an average value accordingly is obtained for the single fiber number of the fiber yarn wrapping.

A particularly suitable embodiment of the sewing thread according to the invention provides that in this case the fiber yarn wrapping of all rovings, seen in the cross-section of the sewing yarn, has a maximum of 41, but preferably less than 41, individual fibers. In other words, in this preferred embodiment of the sewing thread according to the invention, the sewing thread is thus formed by twisting such rovings, in which the individual fiber number of the wrapping is limited to a maximum of 41 individual fibers and preferably less. Such a sewing yarn then has in comparison to an otherwise identically constructed conventional sewing thread the advantages listed above in particular dimensions and also has an extremely small thickness, without thereby deteriorating the sewing properties in any way.

Surprisingly, it has been found that a particularly suitable embodiment of the sewing thread according to the invention which can be used excellently for many sewing operations can be made available by virtue of the fact that this embodiment of the sewing thread according to the invention comprises at least one such roving in which the fiber yarn wrapping has a single fiber number in the cross section of the sewing thread 20 single fibers and 38 single fibers. If this embodiment of the sewing yarn according to the invention exclusively from such rovings created in which the fiber yarn wrapping all of the rovings in the cross section of the sewing yarn seen between 20 individual fibers and 38 individual fibers, so has such a configuration of the sewing yarn invention even further improved sewing properties and can also create even with reducing the use of materials and further increase the production rate.

In order to further optimize the hairiness in the sewing thread according to the invention and furthermore to further increase the sewing performance, a particularly advantageous embodiment of the sewing thread according to the invention provides that in this case the individual fibers of the fiber yarn wrapping of each roving an average staple length between 25 mm and 70 mm, preferably between 33 mm and 43 mm.

Particularly suitable for achieving the coverage of the multifilament core of each roving initially mentioned in the sewing thread according to the invention is when the overall denier of the fibers used for the fiber yarn winding of a roving varies from 25 dtex to 200 dtex in the sewing thread according to the invention.

In particular, the sewing yarn according to the invention has such rovings, which have a total denier between 70 dtex and 400 dtex, these rovings designed as Coregarne then next to the multifilament still trained as a sheath fiber yarn spun with a maximum number of individual fibers of 41 individual fibers and especially less than 41 individual fibers has.

A particularly good correlation between the thickness of the sewing thread according to the invention and the desired properties is achieved when the sewing thread according to the invention consists of two to four rovings of the type described above or to be described below, which are then twisted together to form the sewing yarn. Such a sewing yarn then has in particular a total denier as finished sewing yarn between 140 dtex (2 x 70 dtex) in the minimum and in particular a maximum of 1,600 dtex (4 x 400 dtex) and is almost suitable for all sewing operations occurring.

A particularly high-strength embodiment of the sewing thread according to the invention is achieved when the soul forming multifilament yarn first component of each Vorgarnes or soul at least one roving made of polyester, especially of high-strength polyester exists. By this is meant in particular such a polyethylene terephthalate, which is also offered under the usual commercial name high-strength technical polyester fibers, in which case in particular the intrinsic viscosity between 0.5 dl / g and 0.75 dl / g, preferably between 0, 55 dl / g and 0.63 dl / g, varies. Here, this intrinsic viscosity is determined on corresponding polymer solutions in dichloroacetic acid at 25 ° C.

With respect to the single filament titre, the multifilament first yarn component provided as the core in each roving is it should be noted that this varies in particular between 1 dtex and 6 dtex, preferably between 1.5 dtex and 3 dtex.

Preferably, the sewing thread according to the invention comprises such rovings in which the multifilament first yarn component forming the core of each roving has a filament number in particular between 16 and 300, preferably a single filament number between 24 and 96.

A particularly advantageous sewing behavior have such embodiments of the sewing yarn according to the invention, in which the second yarn component, which forms the wrapping of each roving, a fiber yarn of polyester fibers and / or cellulosic fibers, in particular of cotton fibers is. If in this case a polyester fiber is used as the fiber yarn for the wrapping, this offers the additional advantage over the embodiments of the sewing yarn according to the invention, which have a wrapping of cellulosic fibers, that such a sewing yarn then consists exclusively of polyester and thus in a one-step process using of a class of dyes, namely of disperse dyes, is dyeable.

The term polyester in the present text refers to those fibers or filaments which consist exclusively or largely of polyethylene terephthalate.

A particularly good and less hairy cover is ensured in such embodiments of the sewing thread according to the invention, in which, for the wrapping of each roving, such fibers are selected whose individual fiber titer varies between 0.6 dtex and 4 dtex, in particular between 0.8 dtex and 2 dtex.

For the purposes of the present application, fibers, spun yarns or staple fibers are all intended to designate such thread-like structures that have a limited length, in particular a length between 25 mm and 70 mm.

In particular, each roving in the sewing thread of the present invention has a mass ratio of the first yarn component to the second fiber yarn component, which comprises the wrap of the first yarn component serving as the core, from 50:50 to 75:25 and preferably from 58:42 to 68:32.

A particularly suitable and easy to be colored embodiment of the sewing thread according to the invention provides that in this case each roving an identical from the material first yarn component, i. a core material which is wound with a fiber yarn wrapper identical in material. In other words, in this embodiment, for example, each roving and each of the roving-associated fiber yarn bobbins are made of polyester, so that this all-polyester sewing yarn can be dyed with disperse dyes in one operation.

Especially if the specific strength of each Vorgarnes 40 cN / tex and 55 cN / tex varies, has an inventive sewing thread made of this invention an outstanding strength, so that it is suitable for almost all sewing operations.

This statement also applies to those embodiments of the sewing yarn according to the invention in which preferably the absolute strength of the roving varies between 320 cN and 2,400 cN.

Regardless of the previously reported specific and absolute strengths of the rovings, which are reflected in corresponding, almost identical strength values of the finished sewing thread, it is particularly suitable and advantageous if the sewing thread according to the invention is produced from rovings whose loop strength is between 60% and 70%. absolute and / or aforementioned strengths. Here it has been shown that created from such rovings embodiments of the sewing yarn according to the invention then also sets a loop strength between 60% and 70% of the absolute strengths of the sewing threads, so that accordingly such embodiments of the sewing yarn according to the invention are particularly preferred.

In order to measure this loop strength, two, intermeshing loops of the roving yarn are respectively clamped in a tear tester and loaded under measurement of the force until a rip of the roving yarn or of the sewing yarn occurs.

The present invention further relates to a method for producing the previously described embodiments of the sewing thread according to the invention.

In the method according to the invention for producing the sewing yarn according to the invention, at least two rovings are first of all produced, wherein a roving made of fiber yarns is fed to a spinning device together with the multifilament yarn component serving as the core and spun there to produce each roving yarn. Thereafter, the thus prepared at least two rovings, which are Coregarne, twisted together, whereby the sewing thread according to the invention is formed. In contrast to the prior art, in the process according to the invention, the sliver of the fiber yarn is compacted immediately before feeding to the spinning device so that in the finished sewing yarn, the fiber yarn wrapping of at least one roving over the cross section of the sewing yarn seen a maximum of 41 individual fibers, preferably less than 41 individual fibers and in particular between 20 individual fibers and 38 individual fibers. In other words, in the method according to the invention, the sliver of the fiber yarn (second yarn component) is compressed so far that a reduced number of fiber yarns is spun, preferably twisted, together with the multifilament yarn component serving as the core.

The method according to the invention has, in principle, the same advantages as those already for the sewing thread according to the invention are described so that reference is made to avoid repetition thereof. In particular, however, it should be noted that the method according to the invention is particularly economical to save material, that it is faster to carry out in comparison with the conventional method and that the sewing thread according to the invention produced thereafter has excellent and universally applicable sewing properties, as described in detail above.

In order to bring about the previously described in the sewing thread according to the invention fiber saving in the fiber yarn wrapping, it is particularly appropriate that the produced in the process according to the invention Funte of the fiber yarn is compressed so far immediately before feeding to the spinning device that it is 10 times to 25 -fold volume of the spun roving, in particular 15 times to 20 times the volume of the spun roving. Due to the fact that the sliver of the fiber yarn fed to the spinning device together with the core material usually has only a limited thickness, ie in particular a thickness of approximately 1 to 5 layers of the fiber yarn, the volume of the fiber yarn slub can be approximately equated with the width, which occupies the fiber rag, so that the previously reproduced statement regarding the compaction approximately corresponds to the following statement. This means that in the method according to the invention, the width occupied by the sliver to 10 times to 25 times, in particular 15 times to 20 times, the thickness of the spun roving densified becomes.

In order to bring about the aforementioned compression of the fuse in the method according to the invention in a particularly simple and effective manner and without disturbing the production process, it is particularly advantageous if this compression of the fuse is brought about by compressed air and / or in particular by a vacuum.

The rovings thus produced by the novel process, which are respectively produced by spinning, in particular by twisting the multifilament core material with a fiber yarn component while maintaining the above-mentioned single fiber number of a maximum of 41 individual fibers, in particular less than 41 individual fibers, are then in the inventive Processes these rovings together to form the finished sewing yarn twisted together, for which purpose a rotation coefficient α between 115 and 160 is selected.

In particular, in the method according to the invention, the rotation coefficient α 'used for the production of the roving yarn is between 80 and 130, whereby, of course, the direction of rotation selected for the twisting is opposite to the direction of rotation of the roving.

The above-mentioned rotation coefficients α and α 'are defined as follows: $$\mathrm{Rotation\; coefficient\; \alpha \; resp}\mathrm{,}\mathrm{\alpha \text{'}}=\frac{\mathrm{Turns\; per\; meter}}{\sqrt{\mathrm{nm}}}$$

In this formula, Nm means the yarn count (titer), given in number metric.

The sewing thread according to the invention is explained in more detail below with reference to an embodiment in comparison to a standard sewing thread.

To obtain comparison values, a roving was first spun by the conventional method, using as the starting material for this roving a multifilament core having a denier of 139 dtex and twisting a fiber yarn having a total denier of 65 dtex and a pre-twisting coefficient α 'of 110 in the S direction , For this purpose, a mass ratio of filamentary material (multifilament core) of 68.1% and a fiber yarn portion (spun yarn spun) of 31.9% was selected, the resulting roving then having a denier of effectively 204 dtex. This roving had a linear tenacity of 1040 cN and a specific tenacity of 50.98 cN / tex, with the loop strength being 676 cN.

The fibers of the fiber yarn wrap used had a single titer of 1.3 dtex and had a staple length of 38 mm.

Both the core material and the staple fiber wrap were polyester (polyethylene terephthalate).

Two of these rovings, representing core yarns, were subsequently twisted together to form the finished sewing yarn, with a twisting factor α of 125 selected for this twisting in the Z direction. The resulting finished sewing thread, which is also referred to below as standard sewing thread, had a total titer of 440 dtex.

Cross sections were made from this standard sewing thread to determine the fiber count of the fiber yarn wrap of each roving. For this purpose, five cross-sections were made over a length of 2 m. Microscopically, the number of individual fibers in the fiber yarn wrapping of each roving was then counted. After unwinding 50 m of the standard sewing thread, this measurement was then repeated four times, so that a total of 25 cross-sections were evaluated microscopically.

The measurement of the number of spun yarns in the cross-section of the finished standard sewing yarn revealed that the fiber yarn spun of each roving had an average of 50.17 fibers.

Using the same starting materials (both multifilament core material and fibrous yarn material), a roving was spun according to the claimed method, with the fiber roving 18 times the thickness of the thickness immediately before the spinning device in which the multifilament core material and the fiber roving were jointly introduced of the spun roving using a vacuum has been. For this joint spinning of the multifilament core with the fiber yarn roving, a rotation coefficient α 'was selected which corresponds to the above-mentioned rotation coefficient α'.

The resulting roving had an effective titer of 188 dtex and a mass distribution of filament to fiber fraction of 73.9 to 26.1.

The linear strength of the roving thus prepared was 1060 cN, the specific strength was 56.38 cN / tex.

The loop strength of the roving was 690 cN.

The roving had an S-twist.

Two of these rovings were twisted together to form the sewing yarn, which is referred to below as sewing yarn E, wherein the twisting in the Z direction was carried out under the above-mentioned rotation coefficient α.

By cross-section and microscopic evaluation, the number of fibers in each fiber yarn wrap of each roving was determined, the method of determination being described above.

As a result of this determination of the number of fibers in the fiber yarn batting of each roving yarn, it should be noted that in the sewing yarn E, the number of fibers in the fiber batting of each roving was on average 37.69. The finished sewing yarn had a total denier of 407 dtex.

Thickness measurements on the standard sewing thread and on the sewing thread E revealed that the sewing thread E had a 10% small thickness compared to the standard sewing thread.

Under tightened sewing conditions, i. In industrial sewing at a sewing speed of 7,000 stitches / minute of a 5-ply twill fabric, the sewing performance of the standard sewing thread was compared with the sewing performance of the E sewing yarn. It was found that the sewing performance of both yarns was good, but that the sewing yarn E allowed a 15% longer seam compared to the standard sewing yarn until the yarn breakage occurred. This improved sewing performance clearly demonstrates the stitching advantage of the stitching yarn E, which differs from the standard stitching yarn only in the number of fibers in the fiber yarn wrap of each roving yarn in total titer and smaller caliper.

Claims (23)

1. A sewing yarn having at least two roving yarns, which are twisted together with one another to form the sewing yarn, whereby each roving yarn has the structure of a core yarn, which comprises at least one first multifilament yarn component forming a core, and a second fibre yarn component spun over the core, characterised in that, viewed in the cross-section of the sewing yarn, the fibre yarn thread covering at least one roving yarn contains less than 41 individual fibres.
2. The sewing yarn according to claim 1, characterised in that the fibre yarn thread coverings of all of the roving yarns, viewed in the cross-section of the sewing yarn, contain less than 41 individual fibres.
3. The sewing yarn according to claim 1 or 2, characterised in that the fibre yarn thread covering of the roving yarn or the fibre yarn thread coverings of the roving yarns respectively, viewed in the cross-section of the sewing yarn, contains or contain a number of individual fibres of between 20 individual fibres and 38 individual fibres.
4. The sewing yarn according to one of the preceding claims, characterised in that the individual fibres of the fibre yarn thread covering has a mean staple length of between 25 mm and 70 mm, and preferably between 33 mm and 43 mm.
5. The sewing yarn according to one of the preceding claims, characterised in that the total titre of the fibres of the second yarn component varies between 25 dtex and 200 dtex.
6. The sewing yarn according to one of the preceding claims, characterised in that each roving yarn has a total titre of between 70 dtex and 400 dtex.
7. The sewing yarn according to one of the preceding claims, characterised in that two to four roving yarns are twisted together with one another to form the sewing yarn.
8. The sewing yarn according to one of the preceding claims, characterised in that the first multifilament yarn component, forming the core, consists of polyester, and in particular high-strength polyester.
9. The sewing yarn according to one of the preceding claims, characterised in that the multifilaments of the first yarn components has an individual filament titre of between 1 dtex and 6 dtex, preferably between 1,5 dtex and 3 dtex.
10. The sewing yarn according to one of the preceding claims, characterised in that the first multifilament yarn component has an individual filament count of between 16 and 300, and preferably an individual filament count of between 24 and 96.
11. The sewing yarn according to one of the preceding claims, characterised in that the second yarn component is a fibre yarn made of polyester and/or made of cellulosic fibres, preferably of cotton fibres.
12. The sewing yarn according to one of the preceding claims, characterised in that the fibres of the second yarn component has an individual fibre titre of between 0,6 dtex and 4 dtex, and preferably between 0,8 dtex and 2 dtex.
13. The sewing yarn according to one of the preceding claims, characterised in that each roving yarn comprises a mass ratio of the first yarn component to the second yarn component of 50:50 to 75:25.
14. The sewing yarn according to claim 13, characterised in that each roving yarn comprises a mass ratio of the first yarn component to the second fibre yarn component of 58:42 to 68:32.
15. The sewing yarn according to one of the preceding claims, characterised in that the first yarn component and the second fibre yarn component of each roving yarn is made of the same fibre substrate.
16. The sewing yarn according to one of the preceding claims, characterised in that the specific strength of the roving yarn varies between 40 cN/tex and 55 cN/tex.
17. The sewing yarn according to one of the preceding claims, characterised in that the absolute strength of the roving yarn is between 320 cN and 2.400 cN.
18. The sewing yarn according to claim 17, characterised in that the loop strength of the roving yarn amounts to between 60 % and 70 % of the absolute strength.
19. A process for the manufacture of a sewing yarn according to one of the preceding claims, in which at least two roving yarns are initially manufactured, whereby, to produce each of the roving yarns, a slubbing made of fibre yarns is introduced into a spinning device together with the multifilament yarn component serving as the core, and is spun in said spinning device, and the at least two roving yarns are then twisted together with one another, characterised in that the slubbing of the fibre yarn is compacted directly before introduction into the spinning device to such an extent that in the ready to use sewing yarn the fibre yarn thread covering of at least one roving yarn, viewed over the cross-section of the sewing yarn, comprises less than 41 individual fibres, and preferably between 20 individual fibres and 38 individual fibres.
20. The process according to claim 19, characterised in that the slubbing is compacted directly before introduction into the spinning device to such an extent that it corresponds to 10 to 25 times of the volume of the spun roving yarn.
21. The process according to claim 19 or 20, characterised in that the slubbing is compacted directly before being introduced into the spinning device to 15 to 20 times of the volume of the spun roving yarn.
22. The process according to one of claims 19 to 21, characterised in that the compacting of the slubbing is carried out by means of compressed air and/or by means of a vacuum.
23. The process according to one of claims 19 to 22, characterised in that the at least two roving yarns are twisted with a twist factor α of between 115 and 160 in the formation of the ready to use sewing yarn.