Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof

Definitions

• the invention relates to a process for the production of a cellulosic yarn by spinning a solution of cellulose in a tertiary amine oxide, possibly also containing water and possibly a stabilizer, to give fibers or filaments, precipitation, washing and drying.
• WO95 / 24524 discloses a method for improving the color properties of fabrics made of so-called lyocell yarns.
• Lyocell yarns are solvent-spun cellulose yarns that are made by spinning a solution of cellulose in an organic solvent.
• the solvent is essentially an aqueous tertiary amine oxide, for example N-methylmorpholine-N-oxide (NMMO).
• NMMO N-methylmorpholine-N-oxide
• This mercerization corresponds in principle to that which is customary for cotton fabrics, and an aqueous NaOH solution with a concentration of 10 to 30% by weight at room temperature or slightly elevated temperature (for example up to 35 ° C.) is preferably used for this purpose.
• the fabrics may then be washed with water.
• the tissue is treated with a dilute aqueous acid and several times washed to remove the acid, and then dried.
• WO95 / 24524 in which aqueous NaOH solutions with a concentration of 14% by weight or 25% by weight were used, the fabrics from Lyocell yarns were treated at room temperature over a period of 45 seconds.
• the invention was therefore based on the object of providing a process for the production of cellulosic yarns by spinning a solution of cellulose in a tertiary amine oxide, possibly also containing water and possibly a stabilizer, to give fibers or filaments, precipitation, washing and drying, with which the disadvantages described above are at least reduced.
• the method according to the invention can effectively reduce the fibrillization of Lyocell yarns.
• the process is time-saving and inexpensive because it can be integrated directly into the yarn manufacturing process itself can, and thus no separate treatment step is required for the textile fabrics made therefrom.
• the treatment with the aqueous alkaline solution is preferably carried out over a period of 1 to 15 seconds, particularly preferably 1 to 10 seconds, in particular 2 to 6 seconds.
• An aqueous NaOH or KOH solution is preferably used.
• the concentration of alkali in the aqueous alkaline solution should be between 0.5 and 20% by weight, preferably between 10 and 14% by weight.
• the aqueous alkaline solution can contain further inorganic or organic auxiliaries, such as in particular emulsifiers, salts, glycerol or the like.
• the addition of such surface-active substances advantageously accelerates the wetting of the yarn and thus also of the filaments or fibers with the aqueous alkaline solution.
• salts such as, for example, table salt, or glycerol reduces damage to the yarn surface by treatment with the aqueous alkaline solution.
• a treatment temperature range of 0 to 60 ° C has proven to be favorable, with 20 to 60 ° C, in particular 40 to 60 ° C being preferred.
• the treatment with the aqueous alkaline solution takes place on yarns which have not previously been dried.
• the treatment is therefore preferably carried out after washing the yarn. It is also possible to carry out the treatment with the aqueous alkaline solution before washing, ie after precipitation, but it makes it more difficult to recover the tertiary amine oxide from the wash water, since the tertiary amine oxide and the alkaline solution get into the wash water during subsequent washing.
• the yarn After treatment with the aqueous alkaline solution, the yarn should be neutralized in an aqueous acidic solution such as an acetic acid solution, washed again and then dried.
• an aqueous acidic solution such as an acetic acid solution
• N-methylmorpholine-N-oxide is preferably used as the tertiary amine oxide as the solvent for the cellulose and the cellulose solution optionally contains propyl gallic acid as a stabilizer.
• the wet scrub test apparatus shown schematically in the figure is used to measure the tendency to fibrillation of the cellulosic yarns.
• the wet abrasion test apparatus essentially consists of the elements identified by the reference numbers 1 to 6, which are described in more detail below.
• the yarn 2 is fixed in a PVC block 1.
• the scrubbing load is generated in that the yarn 2 is guided over a rotating glass rod 5 with a diameter of 6 mm, to which a ceramic rod 4 with a diameter of 2.5 mm is attached.
• the glass rod 5 is arranged at a distance of 80 mm from the PVC block 1.
• the glass rod 5 and with it the ceramic rod 4 rotate at a speed of 25 revolutions per minute.
• the yarn 2, tightened by a weight 6 of 3 g is kept wet by dropping water 3.
• the distance of the weight 6 to the glass rod 5 is 60 mm.
• the wet scrub test was carried out for one or two minutes in the examples below.
• the defined and reproducible filament produced with the apparatus was evaluated on a scale with the marks 1 to 6 by microscopic evaluation of the scrubbed yarn area.
• Primary fibrillation means that fibrils are only observed on the fiber surface.
• Secondary fibrillation means that the fibrils are also observed in the deeper layers of the filaments. The more secondary fibrillation progresses, the longer and thicker the fibrils become.
• a grade scale from 1 to 6 was defined using the terms just described. The means
• Primary and secondary fibrillation such as those on untreated
• a high weight loss is disadvantageous from an economic point of view and moreover makes it very difficult to recover the alkaline solution if it is to be used again in the process after cleaning.
• the dissolved cellulose concentrates in the aqueous alkaline solution over time. As such, the separation of dissolved cellulose from the aqueous alkaline solution is difficult. Removing the dissolved cellulose, for example by centrifuging or filtration, is in any case associated with higher costs and with losses of alkaline solution, so that as little weight loss as possible should be aimed for, so that as little cellulose as possible is dissolved in the aqueous alkaline solution.
• the weight loss also affects the yarn properties and leads to filament or fiber breaks and lint formation, which in turn negatively affects the processability of the yarns and leads to a reduction in quality.
• Example 4 While in Examples 1 to 3, the yarns were immersed in a bath with aqueous NaOH for a certain time and thus subjected to the treatment with the aqueous alkaline solution without tension, in Example 4, dried yarns (Trial Nos. 1 to 4) and before yarns which have not yet dried (Trial Nos. 5 to 13) are continuously drawn through a bath with aqueous NaOH.
• the treatment according to Example 4 was therefore not stress-free, but in such a way that the yarn was under a tensile stress of the order of 2 to 10 cN. However, the tensile stress should not exceed 10 cN if possible, since otherwise the yarn could be stretched, which in turn would reduce the desired effect of reducing fibrillation.
• This treatment method is particularly favorable since it allows the yarn treatment according to the invention to be integrated directly into the production process, ie the yarns are passed continuously in the process through the NaOH bath with subsequent baths for neutralization and washing, and ultimately dried and wound up.
• yarns were produced by the customary process, ie precipitation, washing, drying and winding, and then pulled through the NaOH bath from the spool. Both for the initial damp ten and for the dried yarns, the residence time in the bath was 4 s. The neutralization took place in a bath with 60% acetic acid. The yarns were then washed and dried at 180 ° C. The results of these tests are summarized in Table 4.
• Tables 5 and 6 show textile data of yarns produced according to the invention (Table 5) and of comparison yarns (Table 6). Treatment with the aqueous alkaline solution was carried out continuously, as described in Example 4.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Artificial Filaments (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1997
  • 1997-05-27 DE DE59701182T patent/DE59701182D1/de not_active Expired - Fee Related
  • 1997-05-27 AU AU31682/97A patent/AU3168297A/en not_active Abandoned
  • 1997-05-27 JP JP10500189A patent/JP2000511598A/ja active Pending
  • 1997-05-27 ES ES97927053T patent/ES2145609T3/es not_active Expired - Lifetime
  • 1997-05-27 EP EP97927053A patent/EP0902852B1/fr not_active Expired - Lifetime
  • 1997-05-27 WO PCT/EP1997/002742 patent/WO1997046745A1/fr not_active Ceased
  • 1997-05-27 US US09/180,867 patent/US6042767A/en not_active Expired - Fee Related
  • 1997-05-27 AT AT97927053T patent/ATE190098T1/de not_active IP Right Cessation
  • 1997-05-28 TW TW086107240A patent/TW382030B/zh not_active IP Right Cessation
  • 1997-05-30 ID IDP971825A patent/ID18177A/id unknown

Non-Patent Citations (1)

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