KR20050071535A - Stretch polyester and acrylic spun yarn - Google Patents

Abstract

The invention provides a spun yarn comprising polyester bicomponent staple fiber and acrylic staple fiber. The invention further provides a method for making spun yarns and fabrics. The spun yarn of the invention comprises at least 30 weight percent acrylic staple fiber and from 17 to 45 weight percent polyester bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate), based on the total weight of the yarn.

Description

Stretch Polyester and Acrylic Spun Yarn}

The present invention relates to spun yarns comprising polyester staple fibers and acrylic staple fibers, and more particularly to spun yarns wherein the polyester staple fibers are bicomponent fibers which impart high stretch to the yarn.

Bicomponent fibers are known, for example, as described in US Pat. Nos. 3,671,379 and 5,922,433 and International Patent Application Publication WO2000-73552. However, yarns made from such fibers may lack the elongation and resilience required for useful elastic yarns, or may require a higher proportion of fibers than would normally be required for other elastic fibers to achieve the desired level of yarn elasticity.

There is still a need for economical polyester bicomponent staple fibers and acrylic fibers with high extensibility.

Summary of the Invention

The present invention includes at least about 30% by weight acrylic staple fibers and polyester bicomponent staple fibers comprising poly (ethylene terephthalate) and poly (trimethylene terephthalate), wherein the polyester bicomponent fibers comprise the entirety of the yarn. Provided are yarns present from about 17 to about 45 weight percent by weight. In a preferred embodiment, the yarns of the present invention contain at least about 50% by weight acrylic fibers based on the total weight of the yarns. The remainder of the yarn component can be any conventional staple fiber. For example, the yarns of the present invention may contain conventional poly (ethylene terephthalate) staple fibers.

The invention also provides a bicomponent staple fiber; Providing an acrylic staple fiber; Blending and blending the acrylic and bicomponent staple fibers intimately such that the resulting mixture contains at least about 30 wt% acrylic staple fibers and about 17 to about 45 wt% polyester bicomponent fibers based on the total weight of the yarn step; Carding the blended fibers to form a card sliver; Stretching the card sliver; Overlapping and redrawing the card slivers; Converting the stretched sliver to roving; Ring-spun rovings to form the yarns are provided.

The present invention also provides a fabric selected from the group consisting of knitted fabrics and woven fabrics, including spun yarns made by the above method.

The figure shows a schematic cross sectional view of a spinneret pack useful for the production of bicomponent polyester fiber tow.

The inventors have found that yarns comprising acrylic staple fibers and certain proportions of bicomponent staple fibers, including poly (ethylene terephthalate) and poly (trimethylene terephthalate), have unexpectedly high elongation even when bicomponent staple content is limited. Finally found the sex. Spinning yarns can be used, for example, in clothing fabrics such as sweaters, craft yarns, and outdoor fabrics, such as sunshades, tents, tarps, decks and lawn chairs. The fabric may be knitted or woven.

As used herein, “bicomponent fiber” means a fiber in which two polymers are present in a side-by-side or eccentric sheath-core relationship, and refers to a fiber having spontaneous crimped fibers and latent spontaneous crimps not yet expressed. It includes everything.

"Intimate blending" means weighing and thoroughly mixing different fibers in an open space (e.g., weigh-dish hopper feeder) before feeding the mixture to the card or blending the fibers in a dual feed chute on the card. It must be distinguished from stretch-frame blending.

As used herein, “acrylic fiber” means an artificial fiber wherein the fiber-forming material is a long chain synthetic polymer comprising acrylonitrile units, within which acrylic fibers (acrylonitrile units are 85% by weight or more), modacryl Fibers (less than 85 weight percent and at least 35 weight percent acrylonitrile units) and fiber blends thereof.

The spun yarn of the present invention is capable of at least about 30% by weight, preferably at least about 50% by weight, of acrylic staple fibers such as poly (ethylene terephthalate) ("2G-T") and poly (trimethylene terephthalate) ("3G-T"). With a polyester bicomponent staple fiber comprising "), wherein the polyester bicomponent fiber is present at about 45%, preferably at least 25% and less than about 40% by weight based on the total weight of the yarn do. If the polyester bicomponent content is less than about 17% by weight, the extensibility of the yarn may be insufficient as indicated by the total boil-off shrinkage, and the polyester bicomponent content is greater than about 45% by weight. In this case, the elongation properties are almost no longer improved, indicating that the stretchability of the yarn does not follow the mixing law in the composition of the yarn, which was unexpected. The total boiling shrinkage of the yarn may be at least about 32%, which corresponds to stretching about 30% when a 0.045 g / den (0.04 dN / tex) load is applied to the yarn after boiling. Preferably, the total boiling shrinkage is at least about 40%. The yarns of the invention also preferably exhibit higher volumes than conventional acrylic yarns. The yarn may also contain conventional staple fibers, such as conventional poly (ethylene terephthalate) staple fibers.

The bicomponent fiber may have a crimp expression ("CD") value of at least about 35% and is substantially at least about 10%, preferably at least about 20% and at most about 45%, in the absence of substantially interlacing of the fibers. And preferably have a crimp index (“CI”) of about 30% or less. If the CD value is less than about 35%, the yarn may have a total boiling shrinkage that is too small to provide good stretch to the fabrics made therefrom. If the CI value is less than about 10%, mechanical crimping may be necessary for satisfactory carding and spinning. If the CI value is greater than about 45%, the bicomponent staples may have too much crimp for easy carding, even when blended with acrylic staples.

If the CI of the bicomponent staple fibers is low within an acceptable range, higher proportions of polyester bicomponent staple fibers can be used without compromising carding properties. If the CD is high in the range of acceptable values, lower proportions of bicomponent staples can be used in the blended yarns without compromising the total boiling shrinkage. In particular, fiber blend levels, CI, and carding properties are correlated, so if the amount of bicomponent fibers in the blend is low (eg, as low as about 17 weight percent based on the total weight of the yarn), a high CI value (eg, about 45 Satisfactory carding property can be maintained even at values as high as%. Similarly, fiber blend levels, CD, and total boiling shrinkage are correlated, so if CD is high, such as at least about 55%, a satisfactory total boiling shrinkage will be achieved even at about 17% by weight bicomponent fibers based on the total yarn weight. I can keep it.

Blended fibers may be formed into yarns by ring-spinning on cotton systems or worsted spinning frames. The bicomponent staple fibers and the acrylic fibers may have a length of at least about 2.5 cm and up to about 10 cm. If the fiber is shorter than about 2.5 cm or longer than about 5.7 cm, it may be difficult to spin on cotton spinning systems, and if it is shorter than about 5 cm or longer than about 10 cm, it may be difficult to spin in worsted yarn spinning systems.

The bicomponent fibers may have a linear density of at least about 0.7 dtex per fiber, preferably at least about 0.9 dtex and at most about 3.0 dtex per fiber, preferably less than about 2.5 dtex per fiber. If the bicomponent staples have a linear density of greater than about 3.0 dtex per fiber, the feel of the yarn may be rough and difficult to blend with acrylic fibers. If less than about 0.7 dtex per fiber has a linear density, carding can be difficult.

The bicomponent staple fibers may have a weight ratio of poly (ethylene terephthalate) to poly (trimethylene terephthalate) of about 30:70 to 70:30, preferably 40:60 to 60:40. One or both of the polyesters constituting the bicomponent fiber may be a copolyester, and “poly (ethylene terephthalate)” and “poly (trimethylene terephthalate)” include such copolyesters in their meaning. For example, linear, cyclic, and branched aliphatic dicarboxylic acids having 4 to 12 carbon atoms (e.g. butanediic acid, pentanedic acid, hexanediic acid, dodecanediic acid, and 1,4-cyclo-hexanedicarboxylic acid ); Aromatic dicarboxylic acids other than terephthalic acid (eg, isophthalic acid and 2,6-taphthalenedicarboxylic acid) having 8 to 12 carbon atoms; Linear, cyclic and branched aliphatic diols having 3 to 8 carbon atoms (eg 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol and 1,4-cyclohexanediol); Consisting of aliphatic and aliphatic ether glycols having 4 to 10 carbon atoms (eg, hydroquinone bis (2-hydroxyethyl) ether, or poly (ethylene ether) glycols including diethylene ether glycol having a molecular weight of less than about 460) Comonomers selected from the group can be used for the preparation of copoly (ethylene terephthalate). Comonomers may be present in a range that does not impair the benefits of the present invention, eg, at levels of about 0.5 to about 15 mole percent, based on the total polymer component. Isophthalic acid, pentanediic acid, hexanediic acid, 1,3-propanediol and 1,4-butanediol are preferred comonomers.

Copolyester (s) may also be prepared from small amounts of other comonomers so long as they do not adversely affect the benefit of the present invention. Such other comonomers include 5-sodium-sulfoisophthalate, sodium salts of 3- (2-sulfoethyl) hexanediic acid, and their dialkyl esters, which are about 0.2 to 4 based on total polyester It may be incorporated in mol%. For the improvement of acid dyeability, the (co) polyester (s) may also be formulated with polymeric secondary amine additives such as poly (6,6'-imino-bishexamethylene terephthalamide), and the nose of these with hexamethylenediamine. It may also be mixed with polyamides, preferably phosphoric acid and phosphites thereof.

There are no particular restrictions on the external cross section of the bicomponent fiber, and may be circular, oval, triangular, 'snowman' and the like. A 'snowman' cross section has a long axis, a short axis, and can be described as a side-by-side cross section having two or more maximum values when the length of the short axis is plotted relative to the long axis. In one embodiment, the spun yarn of the present invention comprises acrylic staple fibers and bicomponent staple fibers comprising poly (ethylene terephthalate) and poly (trimethylene terephthalate) and having a plurality of longitudinal grooves on the surface thereof. Such bicomponent staple fibers can be considered to have a "scallop-shaped ellipse" cross section that can improve the wicking properties of the polyester bicomponent fiber.

Polyester bicomponent staple fibers in the yarn of the present invention are also conventional additives such as antistatic agents, antioxidants, antibacterial agents, flame retardants, dyes, light stabilizers and matting agents, such as titanium dioxide, so long as the benefits of the present invention are not diminished. It may also include.

The bicomponent staple fibers constituting the spun yarn of the present invention may have a tenacity-at-break of at least about 4 dN / tex and up to about 5.5 dN / tex. If the specific strength is too low, carding and spinning can be difficult, and if too high, fabrics made from the yarns of the present invention may exhibit undesirable pilling. The linear density of the spun yarn may range from about 100 to 700 deniers (111 to 778 dtex).

Knitted fabrics (eg, warp and flat knits, including circular knits and flat knits) and woven fabrics (eg, plain weave and twill) stretchable fabrics can be made from the yarn of the invention.

The method of the present invention includes intimately blending and mixing acrylic staple fibers with polyester bicomponent staple fibers, wherein the bicomponent staple fibers are at least about 17% by weight based on the total weight of the blended fibers. And up to about 45 weight percent, preferably at least about 25 weight percent and up to about 40 weight percent.

It is preferred to use bicomponent staple fibers exhibiting "follow-the-leader" crimps in the method of the present invention because it is believed that the staples improve carding due to their low CI level. Correspondingly, it is preferred that the bicomponent fibers in the tow precursor for staple fibers are 'in-register' and not 'de-registered' with one another.

The blended fibers card the blended fibers to form card slivers, draw card slivers, overlap and redraw card slivers up to three times, convert the drawn slivers to roving, and preferably roving May be further processed by ring-spinning with a linkage of 3 to 5.5 to form the yarn, which yarn may have a boiling contraction of at least about 32%.

The intrinsic viscosity (“IV”) of the polyester is 0.4% concentration at 19 ° C., in accordance with ASTM D-4603-96, instead of the specified 60/40 wt% phenol / 1,1,2,2-tetrachloroethane It was measured on a Viscotek forced flow viscometer model Y-900 using 50/50 wt% trifluoroacetic acid / methylene chloride solution. The measured viscosity was then correlated with the standard viscosity in 60/40 wt% phenol / 1,1,2,2-tetrachloroethane to obtain the reported intrinsic viscosity value.

Tow crimp expression and tow crimp index measurement method of the following two-component fiber was used. To determine the tow crimp index (“CI”), a 1.1 m polyester bicomponent tow sample was weighed and its denier was calculated and the tow size was typically about 38,000 to 60,000 denier (42,000 to 66,700 dtex). Two knots separated by 25 mm were tied to each end of the tow. The first clamp was applied to the inner knot at the first end and a 40 mg / den (0.035 dN / tex) weight was suspended between the knots at the second end to tension the vertical sample. The sample was exercised three times by lifting and slowly lowering the weight. The second clamp is then applied 100 cm below the inner knot of the first end with the weight held between the knots of the second end, and the 0.035 dN / tex weight is removed from the second end and the tension is maintained with the first The sample was turned upside down with the end facing down. A 1.5 mg / den (0.0013 dN / tex) weight is suspended between the knots of the first end, the first clamp is removed at the first end, the sample contracts against the 0.0013 dN / tex weight, and the first from the clamp The length (constricted) to the inner knot of the distal end was measured in cm and expressed as L _r . CI was calculated according to equation (I). To measure tow crimp expression ("CD"), a 1.1 m sample was placed in boiling water for 1 min in non-constricted state and completely dried before adding 40 mg / den (0.035 dN / tex) weight. The same procedure was followed.

CI and CD (%) = 100 × (100cm-L _r ) / 100cm

In order to measure the total boiling shrinkage of the yarn, the yarn was wound from 25 rolls on a standard skew bobbin. The 10 inch (25.4 cm) length (“L ₀ ”) was marked on the sample with a dye maca while the sample was firmly fixed on the bobbin. The skein was removed from the bobbin and placed in boiling water for 1 minute without shrinking, then taken out of water and dried at room temperature. The dry skein was flat and the distance between the dye marks (“L _b0 ”) was measured again. Total boiling shrinkage was calculated from Equation II.

Total BOS (%) = 100 × (L _b0 -L ₀ ) / L ₀

Example 1A

A poly (ethylene terephthalate) of 0.56 IV was prepared in a two step process using an antimony ester transfer catalyst in a second step from terephthalic acid and ethylene glycol in a continuous polymerizer. TiO ₂ (0.3 wt%, based on polymer weight) was added and the polymer was transferred to 285 ° C. and fed into a 790 precoalescence bicomponent fiber spin pack maintained at 280 ° C. using a metering pump. Poly (trimethylene terephthalate) (1.04 IV Soron®, Ei DuPont Di Nemoir & Campani®) was dried, melt extruded at 258 ° C. and weighed independently with a spin pack. .

Figure 1 shows a cross section of the spin pack used. Molten poly (ethylene terephthalate) and poly (trimethylene terephthalate) enter the distribution plate 2 in the holes 1a and 1b and radially throughout the corresponding annular channels 3a and 3b. To be contacted with each other for the first time in the slots 4 of the distribution plate 5. The two polyesters pass through the holes 6 of the metering plate 7 and the counterbore 8 of the spinneret 9 and exit the spinneret through the capillary 10. The inner diameters of the holes 6 and capillary 10 are substantially the same.

The fibers are 142-200 standard cubic to provide a mass ratio of air: polymer in the range of 9: 1 to 13: 1 at a rate of 0.5 to 1.0 g / min per capillary and a weight ratio of 2G-T / 3 / 3G-T polymer of 50/50. Spun into a radial air stream fed at feet / minute (4.0 to 5.6 cubic meters / minute). The quench chamber was substantially identical to that disclosed in US Pat. No. 5,219,506, which is incorporated herein by reference, but used a perforated quench gas distribution cylinder with similarly sized perforations to provide a 'constant' air flow. Using a conical applicator disclosed in U.S. Patent Application Publication No. 2002-0051880-A1, which is incorporated herein by reference, from 0.07% to 0.09% by weight of a spinning finish is applied to the fiber, and the fiber at 1700 meters / minute. I wound it on a package.

Combining the resulting side-by-side circular cross-section fiber about 48 packages to make a tow of about 130,000 denier (144,400 dtex), passing the tow through a feed roll to a first draw roll (2.37 × stretch in a room temperature bath), 2.63 × stretching in two stages, passing it around a second stretching roll (1.11 × stretching) fed at 50 yards / min (46 m / min) at 85 ° C. to 90 ° C. and supplied with hot water spray. It was contacted with six rolls, which were heat treated, oversupplyed by a puller roll by 10%, applied with a conventional textile finish, and then passed through a continuous forced convection drier operating below 35 ° C. The tow had a linear density of 1.3 denier / filament (1.4 dtex / filament), specific intensity of 4.8 g / den (4.3 dN / tex), CI of 34 and CD of 53.

The tow was then collected in a box under substantially no tension and cut into 1.5 inch (3.8 cm) staples for blending with acrylic fibers in Example 1B.

Example 1B

Polyester bicomponent staple fiber from Example 1A and semi-dull 0.9 denier / filament (1.0 dtex / filament) and 1 1/16 inch (2.7 cm) length acrylic staple fiber (T-V111H, Sterling Fibers, Inc. was opened and intimately blended to obtain various weight percents of the two fibers. The fibers were filled in a dual feed chute feeder that fed 70 pounds / hour (32 kg / hour) to a Trutzschler staple card. It was observed that samples with 100% polyester bicomponent fibers could not be carded. Ambient conditions were maintained at 76 ° F. (24 ° C.) and 56% relative humidity. The resulting card sliver was 75 grains / yard (about 5.25 grams / meter). Six strands of card slivers were collected and stretched to 70 grains / yard (4.90 grams / meter) on a Reiter (RSB) draw frame. 6 stretched 70 grain / yard sliver 6 strands are introduced into the same process to produce 70 stretched 2 grain / yard (approximately 48,500 dtex) slivers, which are 0.75 hank (7795 dtex) on a conventional roving frame. ) Roving. The total elongation in the roving process was 6.3X and the linkage was 0.7. The rovings were spun on a Roberts ring-spun frame, producing a 12/1 face number (492 dtex) spun yarn with a linkage of 4.0. The total elongation of the spinning process was 16.0.

The resulting spun yarn had the total boiling contraction ("B.O.C.") shown in Table I, where "Comp." Refers to a comparative sample but not the present invention.

Sample Binary Staple Weight% B.O.S.,% Comp. One 0 13 Comp. 2 15 30 One 30 40 Comp. 3 55 43

The interpolation of the data in Table I shows that when the bicomponent staple fibers occupy about 17% by weight of the yarn, the desired minimum total boiling shrinkage of 32% is obtained, and further improvements are rarely observed above about 45% by weight. It does not.

Claims (10)

At least about 30% by weight acrylic staple fibers based on the total weight of the yarn, and polyester bicomponent staple fibers comprising about 17 to about 45% by weight of poly (ethylene terephthalate) and poly (trimethylene terephthalate) Spinning yarn. The spun yarn of claim 1, comprising at least about 50 wt% acrylic staple fibers and about 25 to about 40 wt% polyester bicomponent fibers, based on the total weight of the yarn. The spun yarn of claim 1, wherein the boil-off shrinkage is at least about 32% and the acrylonitrile units of the acrylic staple fibers are at least 85% by weight. The spun yarn of claim 1, wherein the crimp expression value of the bicomponent fiber is at least about 35% and the crimp index value is from about 10% to about 45%. The spun yarn of claim 1, wherein the crimp index value of the bicomponent fiber is from about 20% to about 30%. a) providing a bicomponent staple fiber; b) providing acrylic staple fibers; c) blending acrylic and bicomponent staple fibers intimately such that the resulting mixture contains from about 17 wt% to about 45 wt% bicomponent staple fibers and at least about 30 wt% acrylic staple fibers based on the total weight of the yarn Compounding by mixing; d) carding the blended fibers to form a card sliver; e) stretching the card slivers; f) overlapping and redrawing the card slivers; g) converting the drawn sliver to roving; And h) ring-spun the roving to form the yarn. 7. The method of claim 6 wherein the mixture contains from about 25% to about 40% by weight bicomponent staple fibers based on the total weight of the yarn. 7. The ring-spinning of claim 6 wherein the ring-spinning provides a linkage of about 3 to 5.5, the polyester bicomponent staple fibers have a total boiling shrinkage of at least about 32%, and the acrylonitrile units of the acrylic staple fibers are 85% by weight. That's how it is. The method of claim 6 wherein the crimp index value of the bicomponent fiber is at least about 10%, the crimp index value of the bicomponent fiber is at most about 45% and the crimp expression value of the bicomponent fiber is at least about 35%. A fabric selected from the group consisting of knitted fabrics and woven fabrics, including a yarn made by the method of claim 6.