EP0119536B1 - Flat knitted article and method of making it - Google Patents

Description

In the industrial manufacture of knitwear, i.e. H. The production of textile fabrics by single thread technology, in which a row of stitches is formed from a horizontally placed thread through the knitting process, which is simultaneously pulled through the previously formed row of stitches, a distinction is made between two machine systems, the circular knitting machine and the flat knitting machine. Beta von Falkai, Synthesefaser, Verlag Chemie, Weinheim - Deerfield Beach, Florida - Basel (1981) provides information on the respective advantages, disadvantages and areas of application on pages 348 to 349.

Flat knitting machines mainly knit outer garments, preferably from yarn-dyed materials. The accessories required for the finished article, such as ribbons, borders, edges, etc., are manufactured on the same machines or special knitting machines. Depending on the weave, the stitch density and the yarn used, all knitted fabrics have different degrees of stretch due to the stitch construction and at the same time only moderate elasticity.

Depending on the yarn used (fiber yarn or textured filament yarn), this elasticity diminishes with prolonged use. The consequences can be bulging or wearing out. This is particularly noticeable in the area of cuffs, turtlenecks and loose sweater parts. There is a limit to the basis weight of a flat knitted piece, since otherwise dimensionally stable flat structures are no longer obtained. This limit depends on the thread size, the stitch density and the weave.

Since yarns with inherent elasticity are available, so-called elastane yarns, which are predominantly made up of segmented polyurethanes, it makes sense to use such yarns in order to achieve permanent elasticity.

Elastane yarns are offered in various forms of trade, on the one hand in their pure form, i.e. H. as bare spandex yarns and on the other hand wound or wound with another type of yarn, for example a polyamide yarn. Wrapping yarns and wrapping yarns therefore consist of a so-called polyurethane core, which is wrapped or wound with a second yarn.

• 1. Durch die Hin- und Herbewegung des Schlittens auf Flachstrickmaschinen unterliegt jedes verwendete Garn, auch das mitverwendete Elasthangarn, einem dauernden Wechsel von zunehmender und abnehmender Spannung. Um dieses Problem zu mindern, wäre der Einsatz von aufwendigen und teuren Vorrichtungen notwendig.
• 2. Um dauerelastiche Flachstrickfertigwaren, vorzugsweise Ränder und Bänder mit einer erhöhten Rücksprungkraft zu erhalten, hat man auf Umwindungs- oder Umspinnungsgarne zurückgegriffen. Diese kommen üblicherweise in rohweiß oder nur wenigen Grundfarben gefärbt auf den Markt. Werden sie in dieser Form eingesetzt, so kommt es aufgrund von Farbunterschieden zum Grundgarn zu dem nicht gewünschten Effekt des « Durchgrinsens •, wie der Fachmann sagt. Soll dies vermieden werden, müßte der Stricker solche Elastangarne in vielen Farben vorrätig halten, möglichst in genau so vielen Farben, wie die Strickgarne aus Wolle, Polyacrylnitril etc. Dies ist bei der prozentualen kleinen Menge an Elasthangam, die mitverstrickt werden muß, unökonomisch.
• 3. Wollte der Stricker bisher blanke Elasthangarne einsetzen, so traten in hoher Zahl Fadenbrüche auf ; im wesentlichen hervorgerufen durch die als Ösen oder Stifte aus unterschiedlichen Materialien, beispielsweise Glas, Porzellan, Metall, Keramik gestalteten Umlenkorgane für den Elasthanfaden.

The processing of bare spandex yarns, wrapping and spinning yarns are state of the art on circular knitting machines. In the case of flat knitting machines it is technically possible to use wound or spun yarns, but this is also practiced to a limited extent. Attempts on flat knitting machines with bare spandex yarns, in particular in the finer numbers dtex 33, dtex 45, dtex 80, dtex 120, have so far failed, for the following reasons:

• 1. Due to the back and forth movement of the carriage on flat knitting machines, every yarn used, including the elastane yarn used, is subject to a constant change of increasing and decreasing tension. In order to alleviate this problem, the use of complex and expensive devices would be necessary.
• 2. In order to obtain permanently elastic flat knitted finished goods, preferably edges and tapes with an increased return force, one has resorted to winding or spinning threads. These usually come in raw white or only a few basic colors. If they are used in this form, the undesirable effect of "grinning through" occurs, as the expert says, due to color differences with the base yarn. If this is to be avoided, the knitter should have such elastane yarns in stock in many colors, if possible in as many colors as the knitting yarns made of wool, polyacrylonitrile, etc. This is uneconomical given the small percentage of elastane yarn that has to be knitted together.
• 3. If the knitter previously used bare spandex yarns, thread breaks occurred in large numbers; essentially caused by the deflecting elements designed as eyelets or pins made of different materials, for example glass, porcelain, metal, ceramic, for the elastane thread.

It has now been found that you can knit bare spandex yarn together with the base yarn if the bare spandex thread is pulled off a bobbin overhead, braked by a sintered ceramic thread brake and transported to the thread guide of the flat knitting machine via deflection elements designed as rollers.

The invention therefore relates to a process for the production of elastic articles on flat knitting machines, which is characterized in that a bare elastane yarn is knitted together with the base yarn, which is drawn off from the bobbin overhead, provided with a defined pretension by a sintered ceramic thread brake and as rolls designed deflection elements is transported to the thread guide of the flat knitting machine. __

Base yarn and elastane yarn can e.g. B. are transported together to the thread guide, with both yarn threads laying around each other in a random manner (wild folding). Preferably, the elastane yarn is run through the spool of the base yarn, whereby the base yarn wraps around the elastane yarn (fold through the spool). However, separate transport is very particularly preferred both yarns, the base yarn being able to be deflected in the usual way by means of pins or tubes, to a plating thread guide, the elastane yarn being plated, that is to say, covered by the base yarn.

A sintered ceramic thread brake gives the elastane thread a defined pretension, the fluctuations of which are caused by the carriage movement of the flat knitting machine can be tolerated, since there is no additional fluctuation in the thread tension on the deflection elements designed as rollers.

The rollers can be made of different materials; Plastic rollers have proven themselves in the tests. The rollers are attached wherever the direction of the elastane thread is changed, for example when passing through the thread monitor.

The elastane yarn preferably passes through the thread brake before it is passed over any roll for the purpose of changing the direction. In particular, the path of the elastane yarn from the spool to the thread brake is smaller than from the thread brake to the thread guide. The pre-tension given in the thread brake is matched to the respectively desired elasticity and the titer of the elastane yarn used in each case.

The elastane yarns used preferably have a titer of 33 to 160 dtex. The pre-tension given to them in the thread brake is preferably one tenth of the specified titer in cN, for example 8 cN for a titer of 80 dtex. The amount of elastane yarn in the total yarn is preferably 2 to 10% by weight.

According to the method according to the invention, dimensionally stable knitted pieces, also by the meter, can be produced for the first time with very light basis weights and adjustable, permanent elasticities, it being particularly advantageous that the width of the knitted piece is no longer specified by the flat knitting machine but by the method according to the invention in Desired way can be increased within certain limits, which inevitably reduces the basis weight.

Finally, the invention relates to flat knitwear containing bare elastane yarn knitted together with the base yarn.

example

• Flachstrickmaschine : 5 E, 2 systemig
• Material : Polyacrylnitrilgarn/Wolle 55/45 Gew.-%, Nm 17/2 dazu im 2. System zusätzlich zum Grundmaterial, Elasthangarn dtex 150
• Bindung : Rechts-Links-Pique
• Rohware : Breite : 97 cm
  • Gewicht : 287 g/m²
• Gedämpfte Ware : Breite : 86 cm
  • Gewicht : 326 g/m²
  • Dehnung : 150 % in der Breite 180 % in der Länge
• Fixierte Ware 1 : Breite : 111 cm
  • Gewicht : 190 g/m²
  • Dehnung : 130 % in der Breite 110% in der Länge
• Fixierte Ware 2 : Breite : 130 cm
  • Gewicht : 156 g/m²
  • Dehnung : 140 % in der Breite 110 % in der Länge
• Der Anteil an Elasthangarn beträgt 3,9 Gew.-%.

A flat knitted piece is produced in the usual way, taking into account the following details. The bare elastane yarn is pulled off overhead, provided with a pre-tension of 15 cN by a sintered ceramic thread brake and transported to the thread guide by rollers. The flat knitted piece is stretched on a tenter and fixed at 185-195 ° C for 30 seconds.

• Flat knitting machine: 5 E, 2 system
• Material: polyacrylonitrile yarn / wool 55/45% by weight, Nm 17/2 in addition in the 2nd system in addition to the base material, elastane yarn dtex 150
• Binding: right-left pique
• Raw goods: Width: 97 cm
  • Weight: 287 g / m ²
• Steamed goods: Width: 86 cm
  • Weight: 326 g / m ²
  • Elongation: 150% in width, 180% in length
• Fixed goods 1: Width: 111 cm
  • Weight: 190 g / m ²
  • Elongation: 130% in width, 110% in length
• Fixed goods 2: Width: 130 cm
  • Weight: 156 g / m ²
  • Elongation: 140% in width, 110% in length
• The proportion of elastane yarn is 3.9% by weight.

Claims (6)

1. Process for the production of elastic articles on flat knitting machines, characterised in that a bare elastane yarn is knitted together with the main yarn, which elastane yarn is drawn off the spool overhead, provided with a specified pretension by means of a sintered ceramic yarn brake, and transported to the yarn guide of the flat knitting machine via deflecting elements in the form of rollers.

2. Process according to Claim 1, characterised in that the elastane yarn runs through the spool of the main yarn.

3. Process according to Claim 1, characterised in that the elastane yarn is plated by the main yarn.

4. Process according to Claim 1, characterised in that the elastane yarns have a titre of 33 to 160 dtex.

5. Process according to Claim 1, characterised in that the quantity of elastane yarn, based on the total quantity of yarn, is 2 to 10 % by weight.

6. Flat knit goods, containing bare elastane yarn knitted together with the main yarn.