Classifications

• • D—TEXTILES; PAPER
  • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
  • D02J—FINISHING OR DRESSING OF FILAMENTS, YARNS, THREADS, CORDS, ROPES OR THE LIKE
  • D02J1/00—Modifying the structure or properties resulting from a particular structure; Modifying, retaining, or restoring the physical form or cross-sectional shape, e.g. by use of dies or squeeze rollers
  • D02J1/22—Stretching or tensioning, shrinking or relaxing, e.g. by use of overfeed and underfeed apparatus, or preventing stretch
  • D02J1/227—Control of the stretching tension; Localisation of the stretching neck; Draw-pins
• • 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
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
  • D01F6/06—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins from polypropylene
• • 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
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
  • D01F6/62—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyesters
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
  • Y10S264/73—Processes of stretching

Definitions

• Such tows are subjected to a uniform drawing process to bring about molecular orientation and crystallisation of the filaments.
• Such uniform tows are then converted into spun yarns, either by cutting the filaments into appropriate staple lengths followed by spinning, or by using a stretch-breaking technique on suitable tow to top converters followed by spinning.
• the staple fibres so produced have uniform shrinkage characteristics. It is known to submit filaments alternately to stretching and relaxing in a cyclic manner in a drawing zone, to yield filaments of improved but uniform properties.
• spun yarns containing the synthetic staple fibres which have variable shrinkage characteristics, that is to say in which the individual fibres have different shrinkage properties or in which the shrinkage properties of the individual filaments vary along their length, before conversion into yarns, can give unusual and desirable effects when the yarns, or fabrics containing such yarns aresubjectcd to a heat shrinking treatment.
• the variable shrinkage in the fibres imparts, e.g., greater bulk and desirable colouring effects on the dyed yarns or fabrics, provided that the shrinkage characteristics are controlled between defined limits.
• filamentary tows of synthetic linear polymers comprising polyesters and polypropylene, as defined, which have variable shrinkage characteristics along their length and which are suitable for conversion into staple fibres and spun yarns, comprising subjecting a substantially uniform tow of undrawn filaments to molecular orientation in a drawing process using drawing conditions one parameter of which selected from draw ratio and temperature, is continuously varied between defined limits at substantially uniform time intervals, so that at a given to'w speed the attained optical birefringence of the filaments becomes 15-200 and their shrinkage in boiling water for 10 minutes l0%-60%, the intervals corresponding to a tow length which is greater than five times the shortest fibre length into which the tow is to be converted but less than 100 m., using draw ratios between 2:1 and 5:1, in a liquid medium maintained at a low temperature of 10 C.l00 (3., followed by converting the tow into staple fibres, tops and yarns, care being taken that the temperature of the filaments, fibres
• One method of carrying out the proces of our invention comprises periodically varying the draw ratio under substantially uniform cyclical intervals. This may be done by varying the speed of the tow between feed means and draw rolls. This may be brought about by varying the relative speed, preferably of the feed means, whilst maintaining the speed of the draw rolls and also the temperature of the liquid medium used in the drawing process, substantially constant.
• the filamentary tow can be forwarded, or wound up at a constant speed, which is desirable as it facilitates the further processing or winding at a constant speed.
• the relative speed of the feed means can be varied by varying the speed of the feed rolls, e.g., by continuously variable gear drives or by other means, known per se, and which are preferably automatically regulated at regular intervals. Alternatively the speed may be maintained constant but the path length between the feed and draw means can be varied by suitable means.
• the speed of the tow and draw ratio is maintained constant but the temperature of the liquid edium is continuously varied preferably at a temperature from about 20 C. below the second order transition temperature of the unoriented filaments up to a temperature which is below that at which flow drawing conditions occur, in the case of polyester filaments.
• intervals at which the drawing conditions are changed are less than five times the desired shortest fibre length, then the overall variability in shrinkage between fibres when blended and spun into yarns will become diminished to such an extent that desired effects are reduced to an unacceptable level.
• Tow draw speeds from 30 to 200 m. per minute are suitable using multifilament tows above 100,000 denier. Slow speeds are required for heavier tows but for lighter tows higher speeds up to 100 m./per min. may be achieved, under suitable heat transfer conditions.
• the tows may be passed through a pre-draw frame bath containing a lubricant before being subjected to the drawing process under variable drawing conditions. It will be appreciated that the filaments after melt spinning should not be heated to a temperature which would affect the shrinkage characteristics, appreciably.
• the drawn tows are then crimped and cut into staple fibres or converted to spun yarns by a stretch-breaking process.
• the tow when left wet from the drawing process will have'its liquid content desirably reduced to below 10% based on the weight of the filaments.
• This tow may be left to dry in air, by passage over heated plates or by applying an air stream provided that care is taken that the temperature of the filaments is not allowed to rise above 50 C. Similarly during subsequent processing the temperatures should not be allowed to rise above 50 C. until the actual shrinkage treatment is carried out, usually this is done after the yarns have been Woven or knitted into fabrics.
• a suitable liquid such as water, or an aqueous solution, emulsion or dispersion of a suitable surface activeagent
• a wide range of draw ratios may be employed without resulting in excessive undrawn yarn.
• the tQW'rnay be split and combined with a longitudinal displacement, or with anothertow of'ditferent shrinkage characteristics so'thaton cut-,
• Exampled to 4 relate to the process using variable draw ratios
• Examples 5 to 7 to the process using variable temperatures
• Example l A'polyethylene terephthalate spun yarn tow of 8000 denier and ofbirefringence 267x10" was drawn between a pair of rollers whose ratio of peripheral speeds was caused to vary continuously between 3.58:1 and 4.5951 at a frequency of 1 cycle per minute, the peripheral speed of the drawing roll .being maintainedat 100 ft. per minute.
• the drawing zone i.e., the yarn between the rolls, was maintained at60 C. by immersion in hot Alternatively if the variable shrinkage is to be obtained by continuously varying the temperature, this may be done by varying the. temperature of thefilaments between .50
• filaments made from'stereo-regular polypropylene tows iwith filaments having an undrawn birefringence of 3x10- which is raised to between 27x10" are suitable when varying the drawn ratio.
• Example 2 V Yarn wasfprocessed as Example lbut drawn at 70 C.
• Example 3 V Yarn was processsed' as in Example 2 but the peripheral speed of the draw rolls was maintained at 50 f.p.m.
• the variability of shrinkage in the ample 1 had a shrinkage which varied sinusoidally along 1ts length with a frequency of 7.7) ⁇ 10' cm.” with a maximum value of 40% and a minimum value of 25%.
• Example 4 A polypropylene towof 1475 denier and of birefrmgence 30x10 units was drawn between a pair of rollers whose ratio. of peripheral speeds was caused to vary continuously between 2.25:1 and 5.50:1 at a frequency of 1' cycle" per minute, the-peripheral speed of the drawing roll being maintained at 100 ft./min.-The
• drawing zone i.e., the yarn between the rolls was maintained at 20 C. by immersion in water.
• filaments and fibres are obtained should not be confused with the desirable controlled dye shade difference obtained in. our process. Also outside the specified limits, frequent filament breakage and stoppages occuryeventhough 'shrinkages within the specified limits of 10-60% may be achieved. A minimum spread 'of shrinkage characteristics of at least 25% is desirable.
• The; drawn yarn so obtained had a boiling water shrinkage which varied sinusoidally along its length at a frequency of .4 .0 10- cmrf with a maximum value of 45% and a minimum value of 13%.
• Example Yarn wasp rocessed as in Example 1 but the draw ratio 7 maintained constant at 3.5 :1 and the bath temperature caused tozvary continuously between 60 C. and 70 C. at a frequency'of ()1 cycle per minute.
• the drawn yarn so obtained had a boiling water shrinkage which varied sinusoidally along its length at a frequency of 4.0 10 cm.- with a maximum value of 58% and a minimum value of 34%.
• a process for the production of filamentary tows of synthetic linear polymer selected from the group consisting of polyesters based on terephthalic acid and stereoregular polypropylene, which have variable shrinkage characteristics along their length and which are suitable for conversion into staple fibres and spun yarns comprising subjecting a substantially uniform tow of undrawn filaments with a birefringence of 12 10- to molecular orientation in a drawing process using drawing conditions one parameter of which selected from draw ratio and temperature, is continuously varied between defined limits at substantially uniform time intervals, so that at a given tow speed the attained optical birefringence of the filaments becomes 15-200 10- and their shrinkage in boiling water for 10 minutes 10%- 60%, the intervals corresponding to a tow length which is greater than five times the shortest fibre length into which the tow is to be converted but less than 100 m., using draw ratios between 2:1 and 5: 1, in a liquid medium maintained at a temperature of C.100 C., followed by converting the tow into staple fibres, tops and yarn
• a process according to claim 1 comprising periodically varying the draw ratio under substantially uniform cyclical intervals.
• a process according to claim 1 comprising periodically varying the draw ratio by varying the speed of the tow between feed means and draw rolls.
• a process according to claim 1 comprising varying the relative speed of the feed means whilst maintaining the speed of the draw rolls and also the temperature of the liquid medium used in the drawing process constant, and forwarding the tow at a constant speed.
• a process according to claim 1 comprising periodically varying the draw ratio by continuously variable gear drives, which are automatically regulated at regular intervals.
• a process according to claim 2 comprising periodically varying the draw ratio under substantially uniform cyclical intervals by maintaniing the speed constant while varying the path length between the feed and draw means by suitable means.
• a process according to claim 1 which includes crimping the tow after it has been drawn in said liquid medium, to remove excess liquid picked up during the drawing operation and reduce the liquid content thereof to below 10%, based on the weight of the filaments and then drying said tow by means selected from the group consisting of drying in air, passage over heated plates and air streams, care being taken that the temperature of the filaments is not allowed to rise above 50 C.
• liquid medium is selected from the group consisting of: water, an aqueous solution of a suitable surface active agent and an aqueous dispersion of a suitable surface active agent.
• a process according to claim 1 which the tow is split and combined with another tow of different shrinkage characteristics so that on cutting staple fibers having continuously variable distribution of shrinkage characteristics are obtained.
• tows are made from polyethylene terephthalate filaments having the variable shrinkage characteristics and a birefringence varying continually along the length in the range of 30-200x10 using temperatures during drawing below the second order transition temperature.
• a process according to claim 1 which includes splitting said tow into longitudinal portions, displacing said portions longitudinal with respect to each other and combining the thus longitudinally displaced portions so as to provide a draw variation across said tow.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10094918

Family Applications (1)

Country Status (4)

Cited By (3)

Citations (9)

• 0
  • BE BE631989D patent/BE631989A/xx unknown
  • NL NL292412D patent/NL292412A/xx unknown
• 1962
  • 1962-05-07 GB GB17421/62A patent/GB1037322A/en not_active Expired
• 1963
  • 1963-04-29 US US276204A patent/US3176374A/en not_active Expired - Lifetime

Patent Citations (9)

Also Published As

Similar Documents