EP0591827B1 - Core yarn comprising a core of high-strength polyester material and method of manufacturing the same - Google Patents

Description

The present invention relates to new core yarns having a selected one Contain soul material, adapted processes for their production, as well as the Use of selected polyester materials for the production of Core yarns.

Core threads are known per se and are used in particular as sewing threads used. Such yarns usually consist of one or more Core threads, each made of a soul thread made of synthetic material consists of spinning with fibers of vegetable, semi-synthetic or fully synthetic Origin or mixtures thereof with simultaneous rotation so is encased that the soul thread is practically completely covered. Core yarns of this type are, for example, from DE-AS-1,150,040, DE-Gbm-75-37,019, which DE-A-2,436,997 and EP-A-241,857 are known.

In these previously known core threads, the soul threads consist of high-strength synthetic material, while the wrapping is usually not essential Contribution to the strength of the yarn. The wrapping serves primarily the protection of the soul material against overheating at high mechanical Stress, for example when used in industrial sewing machines.

Different core materials for core yarns have already been proposed been. So are from DE-A-2,436,997 and EP-A-241,857 high strength Polyester filaments known for this use.

Furthermore, EP-A-173,200 provides multifilament supply threads for the production of Sewing threads are known, which are made from fast-spun, highly drawn and high molecular weight polyester material. The production of core yarns from this material is not explicitly mentioned. The known from this publication Supplying threads can be processed into sewing threads that are difficult under Conditions have a high sewing length, as well as a high seam strength have.

As part of the constant improvement in the productivity of industrial sewing machines, among other things, in a higher number of stitches per unit of time and / or expresses in improved machine run times, there is a need for sewing threads that can be used under difficult sewing conditions and whose thread break rate is as low as possible. Furthermore, the close strength of the formed seam made high demands.

With the present invention, a sewing thread with the desired property profile provided.

a) der Seelenfaden aus Filamenten aus fadenbildendem Polyester besteht, der ein mittleres Molekulargewicht entsprechend einer relativen Lösungsviskosität (ermittelt an Lösungen von 1 g Polyester in 100 ml Dichloressigsäure bei 25 °C) von mindestens 1,9 aufweist, daß

b) der Seelenfaden eine spezifische Festigkeit von mindestens 60 cN/tex besitzt, und daß

c) die Nahtlänge bis zum Bruch des Coregarns auch im gefärbten Zustand bei einer Nähprüfung unter erschwerten Bedingungen mehr als 800 cm beträgt, wobei die Nähprüfung an vier Lagen Baumwolle des Flächen-gewichtes von 350 g/m² bei 5000 Stichen/min, vier Stichen/cm, einer Nähspannung von 220 cN und bei Vorwärtsnähen durchgeführt wird.

The present invention relates to a core yarn containing at least one core thread made of polyester material, which is coated with fibers of vegetable, semi-synthetic or fully synthetic origin or mixtures thereof so that the core thread is practically completely covered. The yarn according to the invention is characterized in that

a) the soul thread consists of filaments of thread-forming polyester, which has an average molecular weight corresponding to a relative solution viscosity (determined on solutions of 1 g of polyester in 100 ml of dichloroacetic acid at 25 ° C) of at least 1.9 that

b) the soul thread has a specific strength of at least 60 cN / tex, and that

c) the seam length until the core yarn breaks even in the dyed state in a sewing test under difficult conditions is more than 800 cm, the sewing test on four layers of cotton with a basis weight of 350 g / m ² at 5000 stitches / min, four stitches / cm, a sewing tension of 220 cN and with forward sewing.

Under the term "covered with fibers ... so that the soul thread is practical is completely covered "is one within the scope of this invention Sheathing the soul thread through the wrapping fibers to understand that the Soul thread under sewing conditions practically no change in terms is subject to its mechanical properties, and in particular that Strengths and the loop strengths of the soul material before and after Sewing are essentially unchanged, e.g. only by a maximum of 10% reduce.

Under the term "specific strength" is the quotient of the maximum tensile force and Understand titer at the moment of tearing.

It has been shown that the use of fast-spun and highly stretched Polyester multifilament yarn in the manufacture of core yarns too Products that, in addition to the desired high yarn tenacity, also for the application have advantageous properties.

This gives excellent loop strength and shrink properties of the core yarn, as well as the seam strength of the seams made with it.

The tenacity (measured according to DIN 53 834) of the invention Core yarns are usually more than 40 cN / tex, preferably 42 to 46 cN / tex. Below that is the maximum traction, based on the titer of the total Understand core yarns.

The loop strength (measured according to DIN 53 843) of the invention Core yarns are usually more than 29 cN / tex, preferably 30 to 34 cN / tex.

The reference elongation at 300 cN load (measured according to DIN 53 834) core yarns according to the invention are usually less than 3.5%, preferably 2.8 to 3.2%.

The maximum tensile force elongation (measured according to DIN 53 834) of the invention Core yarns are usually less than 20%, preferably 16 to 19%. The The maximum tensile strength is the elongation that the yarn is exposed to Experienced maximum traction.

The thermal shrink at 180 ° C (measured according to DIN 53 866, part 3) core yarns according to the invention are usually less than 2%, preferably 1.4 to 1.8%.

It has been found that the favorable combination of properties, especially tensile and transverse strengths of the invention Soul material, leads to particularly good sewing properties.

These can be characterized using a specially developed test method, as described in DE-A-3,431,832. A sewing test with the help of an industrial sewing machine under standardized conditions serves as a measurement. The suitability of a sewing thread can be concluded from the length of the seam produced. An industrial sewing machine from Pfaff with a Nm 90 needle is used; Sewing is done by setting a lockstitch with four stitches per centimeter and a sewing speed of 5000 stitches per minute. The thread is loaded at 220 cN. A fourfold layer of cotton twill is sewn with a basis weight of 350 g / m ² each, which has 33 warp and 20.5 weft threads per centimeter. A standard fabric for work suits was used. The measured value "sewing length" indicates the length of the seam in centimeters until the thread breaks and is an average of ten sewing attempts per test spool.

The core yarns according to the invention show under these test conditions Forward sewing "sewing lengths" of more than 800 cm, preferably 875 to 1050 cm.

Seam strength is another parameter for assessing the properties of Sewing threads. It is determined by the use of an industrial sewing machine, e.g. from Pfaff, with the machine setting specified above. Top and Bobbin threads are the same in this test and each consist of the core yarn according to the invention. The thread load is optimal for a good seam appearance a double layer of cotton twill is sewn. As Cotton twill is made of the same material that is used for the sewing length determination was used. The seam strength is the maximum tensile force a 5 cm wide strip. The tensile force is in a pulling device with a Working speed of 10 cm per minute determined.

Seam strengths can usually be achieved with the core yarns according to the invention achieve more than 35 daN, preferably from 36 to 41 daN.

Core yarns are preferred which have a final titer of 100 to 1500 dtex, in particular from 130 to 750 dtex.

The core thread of the core yarns according to the invention preferably has a titer from 45 to 300 dtex. If there are several soul threads in the core yarn, see above this titer multiplies according to the number of soul threads.

The core yarn according to the invention preferably consists of two together twisted soul threads, each with fibers of vegetable, semi or fully synthetic origin are coated so that the soul thread is practical is completely covered.

The weight ratio of core filaments to wrapping fibers of the invention Coregarnes is usually 30:70 to 50:50, preferably about 40: 60.

Soul and wrapping fibers generally differ in their Single titer. This is usually 2 to 10 dtex for the soul filaments. For the wrapping fiber is usually 1 to in the case of polyester fibers 2 dtex.

The core material of the core yarn according to the invention consists of polyester specifications given above. The soul material is in the form of Multifilament yarns used.

The core thread of the core yarns according to the invention can be made in principle any fibers exist. The term "fiber" is in its broadest To understand meaning, i.e. as multifilament or as staple fiber. Also from In terms of material, the thread is not subject to any restrictions. Leave it in the broadest sense fibers of vegetable, semi-synthetic or fully synthetic origin use, if these are suitable, the soul thread during sewing to protect.

Examples of fibers of plant origin are cotton fibers.

Examples of fibers of semi-synthetic origin are cellulose fibers, e.g. by the xanthate process is available.

Examples of fibers of synthetic origin are fibers from synthetic spinnable polymers and polycondensation products, e.g. made of polyamides, Polyacrylonitrile and in particular from polyesters.

As polyester for the core material and, if necessary, the wrapping yarn come in particular those that are essentially aromatic Dicarboxylic acids, e.g. 1,4-, 1,5- or 2,6-naphthalenedicarboxylic acid, Isophthalic acid or in particular terephthalic acid and aliphatic diols with 2 to 6, especially 2 to 4 carbon atoms, e.g. Ethylene glycol, 1,3-propanediol or 1,4-butanediol can be obtained by cocondensation. Further Hydroxycarboxylic acids are suitable as starting materials for polyesters.

The above-mentioned polyester raw materials can also be condensed small amounts of aliphatic dicarboxylic acids, e.g. Glutaric acid, adipic acid or sebacic acid or of polyglycols, e.g. Diethylene glycol, (2,2'-dihydroxydiethyl ether), Triethylene glycol, (1,2-di- (2-hydroxy-ethoxy) ethane) or also can be modified from lower proportions of higher molecular weight polyethylene glycols.

Another possibility of modification, in particular on the coloring Behavior of the core yarns of the invention influences, is the modification by building blocks containing sulfo groups, e.g. by installing Sulfoisophthalic acid.

The upper limit of the final strength of the core yarns according to the invention depends on other from the chosen degree of condensation in the soul material used Upholstery material. The degree of condensation of the polymer comes in its Viscosity expressed. A high degree of condensation, i.e. high viscosity, leads to particularly high final strengths.

The polyesters used according to the invention as core materials have a relative solution viscosity (determined on solutions of 1 g polyester in 100 ml Dichloroacetic acid at 25 ° C) of at least 1.9.

Polyester is preferably used which has a relative solution viscosity of 1.9 to 2.4, in particular from 1.95 to 2.1.

A preferred polyester material for the production of the soul and optionally of the twisted yarn of the core yarns according to the invention is polyethylene terephthalate or copolyester containing repeating ethylene terephthalate units.

The core threads of the core yarns according to the invention have a maximum tensile force from at least 60 cN / tex, preferably from 65 to 90 cN / tex.

The combination of polyester core and cotton wrap yarn is particularly preferred.

A core material is used to produce the core yarn according to the invention quickly spun polyester multifilament used, which then high was stretched to achieve optimal strength. The use of such high tenacity and fast spun yarns for the production of core yarns So far not described and, like the production of these yarns, is a Subject of the present invention.

i) Herstellung des Seelenfadens aus Multifilamentgarnen auf der Basis von Polyestern, die ein mittleres Molekulargewicht entsprechend einer relativen Lösungsviskosität (ermittelt an Lösungen von 1 g Polyester in 100 ml Dichloressigsäure bei 25°C) von mindestens 1,9 aufweisen, durch Schmelzspinnen von Polyester bei einer Abzugsgeschwindigkeit von mindestens 1500 m/min, vorzugsweise 1900 bis 3200 m/min, und anschließendes Verstrecken unter Bedingungen, so daß das Garn eine Zugkraft bei einer Dehnung von etwa 15% aufweist, die der maximal erzielbaren Höchstzugkraft für das betreffende Garn entspricht oder die bis zu 30% unter diesem Wert liegt, und

ii) Ummantelung dieses Multifilamentgarnes mit Fasern pflanzlicher, halb- oder vollsynthetischer Herkunft oder Mischungen hieraus in an sich bekannter Weise, so daß das Multifilamentgarn praktisch vollkommen abgedeckt ist.

The invention therefore also relates to a method for producing core yarns comprising the measures:

i) Production of the soul thread from multifilament yarns based on polyesters which have an average molecular weight corresponding to a relative solution viscosity (determined on solutions of 1 g of polyester in 100 ml of dichloroacetic acid at 25 ° C.) of at least 1.9 by melt spinning polyester a take-off speed of at least 1500 m / min, preferably 1900 to 3200 m / min, and subsequent stretching under conditions such that the yarn has a tensile force at an elongation of about 15%, which corresponds to the maximum achievable maximum tensile force for the yarn in question or the is up to 30% below this value, and

ii) sheathing this multifilament yarn with fibers of vegetable, semi-synthetic or fully synthetic origin or mixtures thereof in a manner known per se, so that the multifilament yarn is practically completely covered.

The fast-spun polyester multifilament intended as core material has a high orientation, which is noticeable in a high birefringence. Typical values for birefringence are in the range from 15 x 10 ^-3 to 40 x 10 ^-3 .

After the quick spinning, the multifilament is stretched high for an optimal To achieve firmness. It is known to those skilled in the fiber manufacturing field known that a maximum depending on the selected drawing temperature the achievable strength exists. For the production of the invention Core material are the fast spun multifilaments of such drawing conditions, how to subject stretching temperature and degree of stretching so that the optimal strengths for the fast-spun multifilament yarn in question can be achieved with an elongation of about 15%. Among them are also Understand strengths that are up to 30% below this optimal value.

The spinning of the soul material with the thread can in itself known way. Methods of making such casings are e.g. known from DE-A-2,436,997.

The following examples illustrate the invention without limiting it:

example 1

A multifilament yarn made of polyethylene terephthalate is produced by melt spinning and drawn off at 2000 m / min. The polyethylene terephthalate used has a relative viscosity of 1,940. The quickly spun multifilament yarn has a birefringence of 18 X 10 ^-3 , is then drawn in a ratio of 1: 2.97 at 75 ° C and then fixed. The fixing temperature is 230 ° C. A core yarn is made from this multifilament yarn by spinning with cotton. Two of these core yarns are twisted together and then dyed. The properties of the individual production stages are listed in Table 1.

Example 2 (comparative example)

Analogously to Example 1, a core yarn is produced from polyester multifilament yarn and cotton, twisted twice and dyed. In contrast to Example 1, no fast-spun polyester multifilament yarn is used as the core material, but a commercially available high-strength polyester multifilament yarn. The properties of the individual production stages are also listed in Table 1. example 1 Example 2 Filament: Titer dtex 138.4 138.0 Maximum traction cN 926 965 Tenacity cN / tex 66.9 70.0 Maximum tensile strength elongation % 12.8 17.0 Reference elongation b. 45 cN / tex % 6.6 8.2 Loop strength cN / tex 42.8 40.2 Thermal shrink 200 ° C % 7.9 7.0 Coregam / cotton Thread number NM 48.7 48.0 Titer dtex 205.2 208.0 Maximum traction cN 891 894 Tenacity cN / tex 43.4 43.0 Maximum tensile strength elongation % 14.6 17.1 Raw twine: Rotation S T / m 780 780 x2 t T / m 640 690 Titer dtex 411.5 424.0 Maximum traction cN 1904 1952 Tenacity cN / tex 46.3 46.0 Maximum tensile strength elongation % 14.2 18.4 Thermal shrink 180 ° C % 5.8 4.3 Thread dyed: Titer dtex 421.8 425.0 Maximum traction cN 1840 1858 Subtlety cN / tex 43.7 43.7 Maximum tensile strength elongation % 18.8 21.2 Reference elongation b. 300 cN % 3.1 2.4 Thermal shrink 180 ° C % 1.8 1.8 Loop strength cN / tex 31.4 28.5 Seam strength (n10) Dan 38.9 34.5 (35.6-41.2) (32.3 - 37.6) Sewing test of the dyed thread: Sewing length cm 933 768

Claims (9)

1. A core yarn comprising at least one filamentary core made of a polyester material and sheathed with fibers of vegetable, regenerated or synthetic origin or mixtures thereof in such a way that the core is virtually completely covered, characterized in that

   a) the polyester material of the core filaments has an average molecular weight corresponding to a relative solution viscosity (determined on solutions of 1 g of polyester in 100 ml of dichloroacetic acid at 25°C) of at least 1.9,
   in that

   b) the core has a specific strength of at least 60 cN/tex,
   and in that

   c) the seam length to rupture of the core yarn, even in the dyed state, is more than 800 cm in a sewing test under aggravated conditions, said sewing test being carried out on four plies of cotton twill of basis weight 350 g/m² with 5000 stitches/min, four stitches/cm, a sewing tension of 220 cN and with sewing in the forward direction.
2. The core yarn of claim 1, characterized in that the polyester material of the core is polyethylene terephthalate or a copolyester that contains recurring ethylene terephthalate units.
3. The core yarn of claim 1, characterized in that the filament-forming polyester has an average molecular weight corresponding to a relative solution viscosity (determined on solutions of 1 g of polyester in 100 ml of dichloroacetic acid at 25°C) of from 1.9 to 2.4.
4. The core yarn of claim 1, characterized in that the core has a specific strength of from 65 to 90 cN/tex.
5. The core yarn of claim 1, characterized in that the overwrapping yarn is cotton.
6. A process for producing core yarns as claimed in claim 1, comprising the measures of:

   i) producing the core from multifilament yarns based on polyesters having an average molecular weight corresponding to a relative solution viscosity (determined on solutions of 1 g of polyester in 100 ml of dichloroacetic acid at 25°C) of at least 1.9 by melt spinning polyester with a takeoff speed of at least 1500 m/min, preferably from 1900 to 3200 m/min, and subsequently drawing under conditions such that the yarn has a load value at an extension of about 15% which corresponds to the maximum breaking strength obtainable for the yarn in question or is up to 30% below that value, and

   ii) sheathing this multifilament yarn with fibers of vegetable, regenerated or synthetic origin or mixtures thereof in a conventional manner in such a way that the multifilament yarn is virtually completely covered.
7. The process of claim 6, characterized in that the core material used is a polyester multifilament yarn which has a birefringence of from 15 × 10^-3 to 40 × 10^-3 before drawing.
8. The process of claim 6, characterized in that the core material used is a multifilament yarn which was spun at high speed from polyethylene terephthalate or from a copolyester that contains recurring ethylene terephthalate units and which was drawn at temperatures of from 75 to 100°C, the draw ratio used being such that the yarn has a load value at extension of about 15% which corresponds to the maximum breaking strength obtainable for the yarn in question or is up to 20% below that value.
9. The process of claim 6, wherein the core material used is a multifilament yarn spun at high speed from polyethylene terephthalate or from a copolyester that contains recurring ethylene terephthalate units and has a specific strength of from 65 to 90 cN/tex.