EP0091549B1

EP0091549B1 - Method for the simultaneous sizing and drafting of a series of continuous thermoplastic yarns with substantially parallel filaments, for use in fabric production

Info

Publication number: EP0091549B1
Application number: EP83101791A
Authority: EP
Inventors: Vito Ballarati; Franco Tajana
Original assignee: Val Lesina SpA
Current assignee: Val Lesina SpA
Priority date: 1982-03-02
Filing date: 1983-02-24
Publication date: 1986-12-10
Also published as: CA1244635A; IT8219907A0; EP0091549A1; MX156396A; IT1150212B; YU49983A; JPS6117944B2; JPS58197365A; ES8403175A1; EG15505A; ES520212A0; BR8301010A; DE3368299D1; GR77911B; ATE24215T1

Abstract

A method for the simultaneous drafting and sizing of a series of continuous thermoplastic yarns with substantially parallel filaments, for use in fabric production.

Description

This invention relates to a method for preparing warp beams or sectional beams from continuous thermoplastic yarns which are substantially completely drawn and suitable for use on looms for fabric production.
Known processes for preparing continuous yarns from thermoplastic polymers for textile use comprise spinning the polymer in its molten state into filaments, cooling them, combining the filaments to form a yarn and then drafting them.
It is necessary to draft the filaments in order to give the yarn the necessary physical and mechanical characteristics for textile use by molecular orientation. Known processes for preparing a drafted yarn use two different methods.
Consideration will only be given to that more pertinent to the present invention. According to this more pertinent known process, the yarn produced during spinning is collected on to spools in a not yet completely drafted state. Drafting takes place in a subsequent stage by means of suitable multi-position drafting or drafting-twisting machines, each position acting on one individual yarn. With said machines it is very difficult to obtain yarns of perfectly constant characteristics, presumably for the fact that each yarn is treated individually and is thus influenced by minimum differences in the temperature and the mechanical setting-up of each machine position..
In many cases, in order to be able to be used on iooms, yarns collected from drafting and drafting-twisting machines must be subjected to a sizing operation in order to prevent breakage of the individual filaments due to mechanical stresses during weaving. This operation consists of impregnating the yarns with special sizes according to the following process: the beams on which the previously warped yarns are wound are positioned on beam support creels. The yarns, parallel and properly ordered, are passed through suitable apparatus provided with an impregnation tank and squeezing rollers, then through hot air driers or infrared ovens, or over hot cylinders, and are finally collected again on beams by a winding machine.
The US-A-3406437 discloses a method for treating a textile material of substantially parallel yarn ends suitable for a loom, wherein the yarn passes a sizing bath containing a cohesion agent, and then a drying section and a tensioning zone.
In this prior art process no stretching of the yarns occurs: consequently already completely drawn yarns are used.
As stated, the method of the present invention enables an incompletely drafted yarn, as would be obtained from the spinning stage of the said known process, to be used as the starting yarn for preparing said sized warp yarns for weaving, thus dispensing with the normal separate stage in which the yarn is operated on by a drawing or drawing-twisting machine. The new method combines the two separate drawing and sizing stages into one single stage, with obvious technical and economical advantages, using as starting material continuous thermoplastic yarns in which the filaments are substantially parallel and are not completely drawn.
The method, shown diagrammatically on the accompanying drawing, can be described as follows:

The cops of incompletely drafted yarn originating from the spinning operation are loaded in a predetermined number on to a feed creel (A) from which the yarns unwind with constant tension, and are disposed parallel to each other by means of a guide in the form of a comb (B); the yarns pass through a feed and support roller system (C) rotating at constant speed; then through a tank (D) filled with liquid containing at least one cohesion agent kept at a temperature such as to allow drafting of the constituent filaments of the yarn; from here the yarns pass through a system of traction rollers (E) rotating at a constant peripheral speed which is greater than that of the feed rollers (C). The roller system (E) also squeezes the excess liquid remaining in the yarn. The required drafting action and molecular orientation of the filaments is obtained simultaneously for all the individual fed yarns between the feed rollers (C) and traction rollers (E) by virtue of the tension generated by the different peripheral speeds and the softening of the polymer due to heat.

The present invention thus enables the separate drafting and sizing operations of the prior art to be combined into a single simultaneous drafting and sizing operation.
After drafting and sizing, the yarns are dried by passage through ovens (F) which can be of various types, and/or over hot cylinders (G) which also exert a thermal stabilising action on the yarn, and are finally collected on beams or the like by means of a winding machine (H).
A modification to the present method consists of feeding the yarn from beams, small beams, large reels or any other support prepared in a previous passage by a winding machine, instead of directly from the cops loaded on to a. creel.
In this case, it is also possible to combine a number of fractional beams before entering the feed rollers (C) of the drafting stage. The new simultaneous drafting-sizing method for several continuous thermoplastic yarns disposed parallel to each other, according to the present invention, enables considerable economies to be obtained over conventional methods because it completely eliminates the need for a previous drafting stage on the individual yarns using drafting or drafting-twisting machines according to the known process mentioned in the introduction, either before collection from the spinning operation or after collection.
This is attained without substantially modifying the conventional warping and sizing systems which remain substantially the same, but with the mere replacement of the conventional impregnation section by the simultaneous drafting-sizing section.
It has also been found from the numerous tests carried out that fabrics prepared from yarns treated by the new method have excellent characteristics in terms of compactness and uniformity.
The invention is illustrated further by the following non-limiting examples.

Example 1

800 Cops of partially orientated lucid polyester yarn (POY) having the following characteristics are loaded on to a warping feed creel:

Count: 82 Dtex
Number of filaments: 48
Filament cross-section: triangular
Breaking load: 260 grams
Ultimate elongation: 147%
Theoretical residual draft: 1.464 (82/56).

The yarns are warped at a speed of 300 metres/minute and with a tension of 10 grams after checking irregularities with a Lindley apparatus, then collecting them in a single fraction of length 40,000 metres on a beam of height 180 mm.
The fraction warped in this manner is placed on an unwinding stand, and the yarns are passed through the blades of a rectilinear comb.
The yarns are anchored and dragged with a tension of 10 grams by a system of three rollers, which rotate in unison at a constant peripheral speed of 130 metres/minute.
The yarns are then immersed in a tank containing a bath of hot size consisting of a 10% aqueous solution of Adex-Twe acrylic size of the firm Cesalpinia, kept at a constant temperature of 90°C.
A system of three drafting and squeezing cylinders which rotate in unison with a constant peripheral speed of 200 metres/minute acts simultaneously on all yarns so that they are drafted to a ratio of 1.538 relative to the feed.
At the exit of the drafting and squeezing cylinders, the aqueous sizing solution remaining on the yarns is about 80% of the weight of the dry yarn.
The yarns are then dried by passing them through hot air ovens and are then fixed thermally by being passed over and in contact with five hot rotating cylinders kept by steam at a temperature varying from 105°C at the first to 90°C at the last cylinder.
The speed of the hot cylinders is kept slightly less than 200 m/minute so as to allow a certain shrinkage in the length of the yarns before fixing.
At their exit from the fixing cylinders the yarns are wound on beams of height 180 mm in eight fractions of 5000 metres each.
The average characteristics of the yarns drafted and sized in this manner are as follows:

Count: 55.6 Dtex
Breaking strength: 254 grams
Ultimate elongation: 30%
Shrinkage in boiling water: about 8%
Size remaining on the yarn: 8/8.5%.

During the next stage, the eight sized fractions are combined on a weaving beam of height 1550 mm with a total of 6400 yarns.
The beam is loaded on to an LV/51 Nissan water loom and wefted with texturised polyester yarn of count 56 Dtex and 24 filaments, at a speed of 360 beats/minute, with a cloth weave and with a density of 33 wefts/cm.
The fabric is then scoured in full width in a continuous scouring and washing machine at a speed of 15 m/minute. The scouring bath consists of water softened by treatment with ion exchange resin, kept at 90°C and containing 10 cc/litre of 36/38 Be caustic soda, 5 cc/litre of a detergent and 0.5 g/litre of a sequestering agent. This is followed by two wash baths with hot and cold water, and neutralisation with acetic acid.
The scoured fabric is then dyed in a jet cord dyeing machine (Mezzera). The dispersed dye used is Dispers Blue Color Index 056, dissolved in a bath of softened water with a dye concentration of 2 of the weight of the fabric and with the addition of 2% of an evener and 0.2% of a dispersing agent. The pH is adjusted to 4.5 by adding formic acid, and stabilised with monosodium phosphate.
Dyeing is carried out with the following temperature cycle: starting from 60°C, the temperature rises to 130°C at a rate of 1°C/minute; 130°C is maintained for 20 minutes; the temperature falls to 80°C at a rate of 1°C/minute; the dyeing- bath is then discharged and the fabric washed with hot and cold water.
The fabric, centrifuged and dried in hot air, is passed through a stenter machine and thermo- fixed at 180°C at a speed of 25 m/minute. A fabric is obtained having a height of 140 cm with a weight of 55 g/m² and a chain shortening, from raw to finished, of 5.5/6%. During passage over the evenness tester for detecting any fabric- defects, a high uniformity and compactness of the chain yarns is noted, with total absence of lucid yarns.

Example 2

The preceding experiment is repeated by feeding a yarn with the following characteristics from a beam:

Count: 80 Dtex
Number of filaments: 36
Filament cross-section: triangular
Breaking strength: 251 grams
Ultimate elongation: 153%
Theoretical residual draft: 1.536 (80/52).

The feed cylinders are rotated with a peripheral speed of 126 m/minute, whereas the drafting- squeezing cylinders rotate at 200 m/minute, with a drafting ratio of 1.587.
The sizing bat is constituted this time by an 11 % aqueous solution of Kodak 9519 polyester size kept at a temperature of 90°C.
The temperature of the fixing cylinders varies between 105°C and 90°C, and their peripheral speed is slightly less than 200 m/minute.
The average final characteristics of the drafted and sized yarn are as follows:

Count: 52.4 Dtex
Breaking strength: 238 grams
Ultimate elongation: 31%
Shrinkage in boiling water: about 8%
Size remaining on the yarn: 9/9.2%.

The sized fractions are then combined and woven in the same manner as in the preceding example.
Scouring, dyeing and fixing are then carried out as in the preceding example, the only difference being that the scouring bath contains 0.5 g/I of sodium carbonate instead of caustic soda.
A finished fabric of height 140 cm is obtained, with a weight of 53 g/m² and a chain shortening, from raw to finished, of 5.5/6%.
During passage of the fabric through the evenness tester, an almost perfect uniformity of the chain yarns is again observed in this case.

Example 3

Count: 103 Dtex
Number of filaments: 24
Filament cross-section: triangular
Breaking strength: 262 grams
Ultimate elongation: 176
Theoretical residual draft: 1.776 (103/58).

The feed cylinders are rotated at a peripheral speed of 110 m/minute, whereas the drafting- squeezing cylinders rotate at 200 m/minute, with a drafting ratio of 1.818.
The sizing bath is the same as in Example 2, and the fixing cylinder temperature varies from 110°C to 90°C.
The final average characteristics of the drafted and sized yarn are as follows:

Count: 58.2 Dtex
Breaking strength: 257 grams
Ultimate elongation: 28.5%
Shrinkage in boiling water: about 8.5%
Size remaining on the yarn: 8.9/9.2%.

The sized fractions are then combined and woven in the same manner as in the preceding example.
Scouring, dyeing and finishing are also carried out in the same manner as in Example 2.
A finished fabric of height 140 cm is obtained, with a weight of 56 g/m² and a chain shortening, from raw to finished, of 6%.
Good uniformity of the chain yarns was again noted in this case during passage of the fabric through the evenness tester.

Example 4

96 Cops of partially orientated lucid polyester yarn (POY) with the following characteristics are loaded on to eight creel carriages with yarn guides and disc tensioning devices:

Count: 127 Dtex
Number of filaments: 24
Filament cross-section: triangular
Breaking strength: 328 grams
Ultimate elongation: 163%
Theoretical residual draft: 1.628 (127/78).

The yarns are passed through a perforated warping table and then through the blades of a rectilinear comb.
The yarns are then anchored and dragged with a tension of 11 grams by the feed rollers of the simultaneous drafting and sizing system of the preceding examples.
The feed cylinders are rotated at a peripheral speed of 117 m/minute, while the drafting- squeezing cylinders rotate at 200 m/minute with a drafting ratio of 1.709.
The sizing bath is constituted by a 10% aqueous solution of Wisacril PNS acrylic size of the firm Bozzetto, kept at a temperature of 90°C.
The temperature of the fixing cylinders varies between 115°C and 95°C, and their peripheral speed is slightly less than 200 m/minute. The final average characteristics of the drafted and sized yarn are as follows:

Count: 77.2 Dtex
Breaking strength: 320 grams
Ultimate elongation: 31.4%
Shrinkage in boiling water: about 8.3%
Size remaining on the yarn: 8.1/8.4%.

This test was limited to determining the final characteristics of the yarn, as the total number of yarns was not significant for a weaving test. However, the characteristics found by analyzing 32 yarns out of 96 indicated a very low dispersion.

Claims

1. A method for preparing warp beams or sectional beams from continuous synthetic yarns which are substantially completely drawn and sized and are suitable for use on looms for fabric production, said yarns being provided by a feed creel (A) and being dispersed parallel by means of a guide (B), and passed through a tank (D) containing a sizing liquid in which at least one filament cohesion agent is present, characterized in that the method uses as starting material continuous thermoplastic yarns in which the filaments are substantially parallel and are not completely drawn, and in that the drawing and sizing are carried out simultaneously or substantially simultaneously while the yarns are immersed in the tank (D).

2. A method as claimed in claim 1, wherein the drawing operation is carried out by two roller systems (C) and (E) rotating at suitably different speeds and disposed at the ends of the tank (D).

3. A method as claimed in one of the preceding claims, wherein the yarns can be drawn simultaneously by several traction systems in order to correspondingly vary the drawing ratio.

4. A method as claimed in one of the preceding claims, wherein the thermoplastic yarns are mainly polyester, polyamide, polyethylene or polypropylene yarns, or their modifications.

5. A method as claimed in one of the preceding claims, wherein the liquid containing the cohesion agents has a temperature such as to enable the filaments constituting the yarn to be drawn.

6. A method as claimed in claim 1, wherein a polyester or acrylic size is used for the sizing.