CN111118628B - PBT/PET double-component elastic yarn and preparation method thereof - Google Patents

PBT/PET double-component elastic yarn and preparation method thereof Download PDF

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CN111118628B
CN111118628B CN201911350219.3A CN201911350219A CN111118628B CN 111118628 B CN111118628 B CN 111118628B CN 201911350219 A CN201911350219 A CN 201911350219A CN 111118628 B CN111118628 B CN 111118628B
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pbt
pet
melt
spinneret
distributed
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CN111118628A (en
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范红卫
汤方明
王山水
王丽丽
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Jiangsu Hengli Chemical Fiber Co Ltd
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Jiangsu Hengli Chemical Fiber Co Ltd
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/28—Formation of filaments, threads, or the like while mixing different spinning solutions or melts during the spinning operation; Spinnerette packs therefor
    • D01D5/30—Conjugate filaments; Spinnerette packs therefor
    • D01D5/32—Side-by-side structure; Spinnerette packs therefor
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/22—Formation of filaments, threads, or the like with a crimped or curled structure; with a special structure to simulate wool
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/253—Formation of filaments, threads, or the like with a non-circular cross section; Spinnerette packs therefor
    • 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
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
    • D01F8/14—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyester as constituent
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2401/00—Physical properties
    • D10B2401/06—Load-responsive characteristics
    • D10B2401/061—Load-responsive characteristics elastic

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  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Multicomponent Fibers (AREA)

Abstract

The invention relates to a PBT/PET double-component elastic yarn and a preparation method thereof, wherein the PBT/PET double-component elastic yarn is extruded on the same spinneret plate; splitting the PET melt into two paths: one path is directly extruded (flows through a spinneret orifice m) after being distributed; the other path is distributed with the PBT melt according to a parallel composite spinning mode and then extruded (flows through a spinneret orifice n); m and n are linear spinneret orifices, the number ratio of the linear spinneret orifices is 1: 5-10, and when the PET melt and the PBT melt are distributed in a parallel composite spinning mode and then extruded out, the PET melt and the PBT melt are respectively extruded out from two sides of a long symmetrical axis of the cross section of each linear spinneret orifice; preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the single filaments in the prepared PBT/PET double-component elastic yarn are randomly distributed in the curling direction. The invention solves the problems of poor crimping performance of the PBT/PET parallel composite monofilament and uneven strip shade of the knitted fabric.

Description

PBT/PET double-component elastic yarn and preparation method thereof
Technical Field
The invention belongs to the technical field of polyester fibers, and relates to a PBT/PET double-component elastic yarn and a preparation method thereof.
Background
Crimp is an important indicator of fiber, affecting textile processing and final end product characteristics and application properties.
In the family of the bicomponent composite fiber, the side-by-side bicomponent composite fiber is an important member, and the fiber is bent deviating from the axial direction of the fiber by utilizing the difference of the heat shrinkage performance of the two components, so that the fiber presents permanent three-dimensional spiral crimp, and the crimp similar to wool fiber is obtained. The fiber is curled without deformation processing carried out when common thermoplastic fibers are curled, so that thermal damage of chemical fibers is avoided, the fiber is generally called self-curling fiber and also called three-dimensional curling fiber, and the curling has the characteristics of durability, stability, good elasticity and the like, and can endow fabrics with better elasticity, bulkiness and coverage. Parallel two-component composite fibers with different performances can be obtained by changing the characteristics of the component high polymer, the cross section shape, the component distribution, the component proportion, the spinning drafting and the heat setting process parameters, and the parallel two-component composite fibers have the advantage of designable performances and higher application value, so the parallel two-component composite fibers are favored and valued by the fiber manufacturing industry.
With the industrial production and the expansion of the application range of PBT high polymer and fiber, a new PBT/PET side-by-side bicomponent fiber with more vitality is produced. The PBT fiber has better softness than chinlon, better dyeing property than terylene, and bulkiness similar to acrylon, and has good application in the fields of wool spinning, cotton spinning, filament weaving and the like.
However, in bicomponent side-by-side conjugate fibers, two components with different shrinkage rates generally form a flat interface, and the bending occurs in the direction normal to the interface. The conventional PBT/PET parallel composite fiber has short interface length and long interface normal length in the cross section, so that the bending-resistant section modulus is large when the fiber is bent, the fiber has a large crimp radius, and the crimp performance of the fiber is not ideal.
Furthermore, while FDY filaments of PBT/PET fibers have been applied to woven fabrics, very formidable problems arise in advancing the wider application of fibers in the knitting field: because the structured spiral crimp structure is formed when the side-by-side PBT/PET self-crimping composite fiber is subjected to heat shrinkage, the surface of the woven knitted fabric has random strip-shaped uneven patterns, and the random strip-shaped uneven patterns are particularly obvious on plain woven fabrics. The problem causes that the PBT/PET fiber can not be applied to a plurality of knitted products, and the development and application of the PBT/PET fiber knitted fabric are seriously restricted.
Therefore, it is very important to improve the crimp property of the PBT/PET double-component composite fiber and solve the problem of uneven stripe shade of a knitted fabric prepared from the PBT/PET double-component composite fiber.
Disclosure of Invention
The invention provides a PBT/PET double-component elastic yarn and a preparation method thereof, and aims to solve the problem of poor crimp property of a PBT/PET double-component composite fiber in the prior art. According to the invention, a mode that PET melt and PBT melt are respectively extruded from two sides of a long symmetry axis of the cross section of the linear spinneret orifice is adopted, under the same cross section area, the interface length is increased, the interface normal length is reduced, the bending-resistant section modulus in the curling direction is obviously reduced, the curling radius of the fiber is further reduced, and the curling performance of the bi-component parallel fiber is improved.
The invention provides a PBT/PET double-component elastic yarn and a preparation method thereof, and aims to solve the problem of uneven strip shade of randomness when a PBT/PET double-component composite fiber is applied to a knitted fabric product. The PBT/PET double-component elastic yarn consists of the PET monofilament with the straight-line cross section and the PBT/PET parallel composite monofilament with the straight-line cross section, breaks through the neat left and right spiral shapes formed by pure PBT/PET parallel composite fibers, and further solves the problem of uneven strip shade shape of a knitted fabric made of the PBT/PET parallel composite fibers.
In order to achieve the purpose, the invention adopts the following scheme:
a preparation method of PBT/PET double-component elastic yarns comprises the steps of extruding the PBT/PET double-component elastic yarns on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path is distributed together with the PBT melt according to a parallel composite spinning mode and then extruded;
the spinneret orifices m for direct extrusion flow and the spinneret orifices n for extrusion flow distributed in a parallel composite spinning mode are in-line spinneret orifices, and the number ratio of the spinneret orifices m to the spinneret orifices n is 1: 5-10;
when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode, the PET melt and the PBT melt are respectively extruded from two sides of a long symmetrical axis of the cross section of the linear spinneret orifice;
and preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain the PBT/PET double-component elastic yarn.
Specifically, the PET melt is divided into two paths, one path is directly extruded after being distributed, the other path and the PBT melt are extruded after being distributed in a parallel composite spinning mode to realize replacement, and correspondingly, the number and the position relation of the distribution holes and the guide holes are reasonably set so as to ensure the smooth operation of the division; the invention ensures that the replaced part occupies proper proportion of the whole by controlling the ratio of the number of the spinneret orifices m which directly extrude and flow through to the number of the spinneret orifices n which extrude and flow through after being distributed according to the parallel composite spinning mode, thereby not only effectively solving the problem of uneven stripe shade, but also maintaining the excellent performance of the PBT/PET parallel composite fiber; the invention distributes the spinneret orifices m and the spinneret orifices n according to the concentric circles, and controls the spinneret orifices m to be positioned at the inner ring of the concentric circles as much as possible, thereby ensuring that the PET fiber can be fully doped into the PBT/PET parallel composite fiber; according to the invention, the intrinsic viscosity of the PET melt is selected to be 0.50-0.58 dL/g, the intrinsic viscosity of the PBT melt is 1.00-1.20 dL/g, and the temperature of the spinning manifold III, the temperature of the PET melt spinning manifold I and the temperature of the PBT melt spinning manifold II are reasonably set, so that the apparent viscosities of the PET component and the PBT component extruded from the spinneret orifice are relatively close, and the smooth spinning is ensured; the FDY process is adopted, so that the prepared product has good curling performance, high curling shrinkage rate, high curling stability, high tightening elongation and high curling elastic recovery rate, and good mechanical properties.
The principle of the invention is as follows:
the three-dimensional crimp structure of the PBT/PET double-component elastic yarn is similar to a wool fiber structure and is generated by the characteristics of the fiber and the asymmetric structure, the asymmetric structure is that two components are in the same composite fiber and are different from a conventional single-component fiber, and when the thermal shrinkage rates of the two components are different (namely the characteristics of the fiber), because the crimping direction of the fiber is along the direction with high thermal shrinkage rate, the PBT with higher thermal shrinkage rate in the PBT/PET fiber is positioned on the inner side of the spiral bend of the three-dimensional crimp fiber, and the PET with lower thermal shrinkage rate is positioned on the outer side of the spiral bend of the three-dimensional crimp fiber.
For the PBT/PET double-component composite fiber, the characteristics of the fiber (namely the heat shrinkage rate of the PBT and the PET) are certain, so the asymmetric structure characteristic is a main factor influencing the crimping form of the PBT/PET double-component composite fiber. For the two-component side-by-side composite filament, even if the equal volume ratio is adopted and the filament is extruded from a perfect circle spinneret orifice, the cross section of the fiber is not perfect circle generally due to the difference of the density and the orifice bulking of the two components, a group of orthogonal major axis y and minor axis x can be defined to represent the structure approximately like an ellipse, and the ratio of the major axis to the minor axis represents the degree of deviation of the cross section of the fiber from the perfect circle, namely the degree of profile.
The major axis y and the minor axis x have a bending section modulus W when the fiber is bent along the major axis yyIs composed of
Figure 1
(ii) a Bending section modulus W of the fiber when bent along the minor axis xxIs composed of
Figure 2
The smaller the bending section modulus, the smaller the crimp radius of the fiber; the smaller the crimp radius of the fiber, the larger the crimp number, and the higher the crimp elastic recovery, the better the elastic properties of the fiber.
The straight spinneret orifice is characterized in that: the length of the major axis y of the cross-section is much greater than the length of the minor axis x, i.e. the flexural section modulus WyAnd flexural section modulus WxIn the calculation formula (2), y is larger than x, and the comparison shows that the bending section modulus WyGreater than bending section modulus WxIn order to improve the crimping performance of the fiber, the crimp radius of the fiber needs to be reduced, and in order to reduce the crimp radius of the fiber, the bending section modulus of the fiber needs to be reduced, so that when the in-line PBT/PET two-component composite fiber is controlled to be bent along the short axis x, a smaller bending section modulus W can be obtainedxAnd further obtain better elastic performance. According to the invention, the PET melt and the PBT melt are respectively extruded from two sides of the long symmetrical axis of the cross section of the linear spinneret orifice, so that the bending direction is along the short axis x, and the crimp property of the PBT/PET bicomponent composite fiber is further improved.
In addition, the bending section modulus W of the in-line PBT/PET double-component composite fiber is found by comparing the bending section modulus of the PBT/PET double-component composite fiber with a flat, pear or round cross section under the conditions of same materials, equal proportion and consistent finenessyMaximum, flexural section modulus WxAt minimum, becauseThe bending direction of the linear PBT/PET double-component composite fiber is controlled along the short axis x, and the crimping performance which is better than that of PBT/PET double-component composite fibers with other cross section shapes can be obtained.
In the prior art, the PBT/PET double-component composite fiber can be straightened under the stretching action of external force due to the three-dimensional spiral crimping, and can be well restored to the original crimping state when the external force action is removed. Research shows that in a bundle of PBT/PET double-component composite fibers, the crimping form of the composite fibers simultaneously has relatively regular left and right spiral yarn sections and random crimping yarn sections, and the length and the arrangement of each yarn section are random on the whole. Due to the difference of fiber inclination state and mechanical response behavior, when the PBT/PET composite fiber is used for weaving knitted fabrics, the difference of yarn reflection effect and tension unevenness is caused, protrusions or recesses are randomly formed on the cloth surface, and uneven transverse stripes with randomly changed brightness and darkness, namely uneven striped shape, are found by apparent inspection.
The mixed filament yarn consists of the PET monofilament and the PBT/PET parallel composite monofilament, the PBT/PET parallel composite monofilament obtains three-dimensional crimped fiber after relaxation heat treatment, and the PET monofilament does not curl after relaxation heat treatment; in the same bundle of mixed filament yarn, the number ratio of PET monofilaments (corresponding to the spinneret orifices m) to PBT/PET parallel composite monofilaments (corresponding to the spinneret orifices n) is 1: 5-10, the PET monofilaments have the effect of breaking and forming a neat left and right spiral form, the PBT/PET parallel composite monofilaments have the effect of providing elasticity for the mixed filament yarn through self-curling, the elasticity of the mixed filament yarn cannot be well reflected due to too many PET monofilaments, the effect of breaking and forming the neat left and right spiral form cannot be achieved due to too few PET monofilaments, the PET monofilaments and the PBT/PET parallel composite monofilaments are mixed according to a specific ratio, the elasticity of the mixed filament yarn is ensured, the neat left and right spiral form formed by the PBT/PET parallel composite monofilaments is broken, the curling form of each PBT/PET parallel composite monofilament is different from other fibers, and the uneven shape of a strip is eliminated.
In addition, the PBT/PET double-component elastic yarn is spirally curled in a three-dimensional manner in the longitudinal direction, the three-dimensional curling enables the fabric to have good fluffiness, curling performance, extensibility and soft handfeel, and meanwhile, the irregular spiral curling enables the fabric to have good moisture-conducting performance.
As a preferable technical scheme:
according to the preparation method of the PBT/PET bicomponent elastic yarn, the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50:50, and the equivalent diameter ratio of the spinneret orifice m to the spinneret orifice n is 1: 1.
According to the preparation method of the PBT/PET double-component elastic yarn, the length-width ratio of the cross section of the spinneret hole m or the spinneret hole n is 9-18: 1, and the length-width ratio is the ratio of the length to the width; the aspect ratio is set to a range that allows the fibers to achieve a smaller radius of curvature.
According to the preparation method of the PBT/PET double-component elastic yarn, all the spinneret holes are distributed in concentric circles, the spinneret holes on the same circle are m or n, and the spinneret holes on the outermost circle are n, so that the PET monofilaments are mixed into the middle of the PBT/PET parallel composite monofilaments, and a uniform left and right spiral form is broken; otherwise, more PET monofilaments are distributed at the outermost circle, so that the internal PBT/PET parallel composite monofilaments still have regular left and right spiral shapes.
According to the preparation method of the PBT/PET double-component elastic yarn, the parameters of the FDY process are as follows: the spinning temperature is 270-276 ℃, the cooling temperature is 20-25 ℃, the first-roller speed is 2000-2200 m/min, the first-roller temperature is 70-80 ℃, the second-roller speed is 2800-3000 m/min, the second-roller temperature is 125-130 ℃, and the winding speed is 2730-2910 m/min; the temperature of the relaxation heat treatment is 90-120 ℃, and the time is 20-30 min.
According to the preparation method of the PBT/PET double-component elastic yarn, the spinneret orifice m is composed of the guide orifice E, the transition orifice and the capillary micropore which are connected in sequence, the spinneret orifice n is composed of the guide orifice D, the transition orifice and the capillary micropore which are connected in sequence, the guide orifice E is connected with the distribution orifice A, and the guide orifice D is simultaneously connected with the distribution orifice B and the distribution orifice C; the distribution holes A, B and C are positioned on the distribution plate in the spinning manifold III; the shunting is to convey the PET melt to the distribution hole A and the distribution hole B through the spinning manifold I, and simultaneously convey the PBT melt to the distribution hole C through the spinning manifold II.
According to the preparation method of the PBT/PET double-component elastic yarn, the intrinsic viscosity of a PET melt is 0.50-0.58 dL/g, the temperature of a spinning manifold I is 275-280 ℃, the intrinsic viscosity of the PBT melt is 1.00-1.20 dL/g, the temperature of a spinning manifold II is 260-265 ℃, and the temperature of a spinning manifold III is 270-276 ℃ (the temperature of the spinning manifold III is the spinning temperature). In order to ensure the smooth spinning, it is necessary to ensure the same flow state when the two components are extruded from the same spinneret orifice as much as possible, i.e. the apparent viscosity of the melt is close (generally, the greater the apparent viscosity, the poorer the flow property); the apparent viscosities of PET and PBT can be adjusted through temperature, the invention can be matched with the intrinsic viscosity of PET melt and the intrinsic viscosity of PBT melt through reasonably setting the temperature of a spinning box III, the temperature of a PET melt spinning box I and the temperature of a PBT melt spinning box II, the PET adopts high-temperature melting and low-temperature spinning, and the PBT adopts low-temperature melting and high-temperature spinning, so that the degradation of the PBT can be reduced, although the temperature difference of two components in the box is larger, the two components exchange heat when entering the same composite component, the temperature of the PET component is reduced, and the temperature of the PBT component is raised, so that the apparent viscosities of the two components extruded from a spinneret orifice are close to be consistent, and the smooth proceeding of spinning can be ensured.
The invention also provides the PBT/PET double-component elastic yarn prepared by the preparation method of the PBT/PET double-component elastic yarn, which consists of the PET monofilament with the in-line cross section and the PBT/PET parallel composite monofilament with the in-line cross section, wherein the PBT and the PET in the PBT/PET parallel composite monofilament are distributed on two sides of the long symmetrical axis of the in-line cross section; the single fibers in the PBT/PET double-component elastic yarn are randomly distributed in the curling direction, the random distribution is a mathematical concept, namely the curling form of each fiber is different from that of other fibers, so that the prepared fabric has no uneven strip shade.
As a preferred technical scheme:
according to the PBT/PET double-component elastic yarn, the PBT/PET double-component elastic yarn has the crimping shrinkage rate of 52-56%, the crimping stability of 83-88%, the contraction elongation of 93-97%, the crimping radius (namely the radius of a projection circle of a crimping ring) of 0.0786-0.103 mm, the crimping elastic recovery rate of 92.5-97.6%, and the screw pitch (namely the distance between one point on a three-dimensional spiral crimping curve and the same point on an adjacent crimp) of 0.109-0.784 mm.
According to the PBT/PET double-component elastic yarn, the breaking strength of the PBT/PET double-component elastic yarn is more than or equal to 3.0cN/dtex, the elongation at break is 35.0 +/-3.5%, and the total titer is 75-150 dtex.
Preparing the prepared PBT/PET double-component elastic yarn into a knitted fabric, and testing the uneven condition of the strip shade of the knitted fabric, wherein the testing process comprises the following steps: firstly, acquiring an image of the knitted fabric, converting the image into a gray image, then performing primary processing and secondary processing on the gray image, and calculating a parameter D, and representing the uneven degree of the striped shadow shape by using the parameter D, wherein the gray image comprises a striped shadow region, a high gray value region of a non-striped shadow region and a low gray value region of the non-striped shadow region; the first processing is to change pixel points in a high gray value area of a non-bar-shadow area in a gray image into pure white points; the second processing is to change the pixel points of the low gray value area of the non-shadow area in the gray image into pure white points; the calculation formula of the parameter D is as follows: d ═ Σ B/a, where Σ B represents the number of pixels having a gray scale value of 0 in the grayscale image, and a represents the total number of pixels in the grayscale image.
The strip shade unevenness can be judged if the D value is more than or equal to 3 percent, and the serious strip shade unevenness can be judged if the D value is more than or equal to 10 percent. The test result of the knitted fabric made of the PBT/PET double-component elastic yarn disclosed by the invention is as follows: the D value of the knitted fabric made of the PBT/PET double-component elastic yarn is less than or equal to 1.0 percent; this demonstrates that the PBT/PET bicomponent elastic yarn in this application does not have the problem of "stripe-like unevenness" in the knitted fabric.
Has the advantages that:
(1) according to the preparation method of the PBT/PET double-component elastic yarn, the mixed filament yarn composed of the PET monofilament and the PBT/PET parallel composite monofilament is adopted, and the spiral crimp state of a single fiber in the multifilament is changed after relaxation heat treatment, so that the crimp state of each fiber is different from that of other fibers;
(2) according to the preparation method of the PBT/PET double-component elastic yarn, the mixed filament yarn composed of the PET monofilament and the PBT/PET parallel composite monofilament cannot form spiral curled regular arrangement, so that the problem of uneven strip shade formed by the PBT/PET parallel composite fiber in a knitted fabric is solved;
(3) the PBT/PET double-component elastic yarn prepared by the preparation method of the PBT/PET double-component elastic yarn is excellent in comprehensive performance and wider in application.
Drawings
FIG. 1 is a schematic view of the melt distribution of the present invention;
FIG. 2 is a schematic cross-sectional view of the PBT/PET bicomponent elastic yarn of the invention;
wherein A, B and C are independent dispensing holes, and D and E are independent guide holes.
Detailed Description
The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
The crimp shrinkage and crimp stability of the invention are obtained by testing the tow in GB/T6506-2001 synthetic fiber textured yarn crimp performance test method.
The compression elongation (which reflects the elasticity and crimp degree of the textured yarn, the fiber is subjected to light load and then heavy load, and the ratio of the length difference to the crimp length under the two loads is calculated) and the crimp elastic recovery test method are as follows:
firstly, cutting two fiber samples with the length of about 50cm, putting the two fiber samples into hot water with the temperature of 100 ℃ for treatment for 30min, taking the two fiber samples out, naturally drying the two fiber samples, cutting the sample with the length of about 30cm, fixing one end of the sample, and loading a load of 0.0018cN/dtex on one end of the sampleMarking at 20cm for 30s, namely obtaining the initial length l of the sample1(ii) a Then, the load of 0.09cN/dtex is loaded for 30s, and the position of the mark point is measured, namely the length l when the sample is loaded with heavy load2(ii) a Finally, removing the heavy load, retracting the sample for 2min without load, then adding the load of 0.0018cN/dtex, continuing for 30s, and measuring the position of the mark point on the scale, namely the recovery length l3(ii) a The percent elongation to Compression (CE) and the crimp elastic recovery (SR) are calculated as follows:
CE＝(l2-l1)/l1*100；
SR＝(l2-l3)/(l2-l1)*100。
example 1
A preparation method of PBT/PET double-component elastic yarn comprises the following steps:
(1) the PBT/PET double-component elastic yarns are extruded on the same spinneret plate, and a melt distribution schematic diagram is shown in figure 1, and specifically comprises the following steps:
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path is distributed together with the PBT melt according to a parallel composite spinning mode and then extruded; wherein the intrinsic viscosity of the PET melt is 0.50dL/g, and the intrinsic viscosity of the PBT melt is 1.20 dL/g;
the spinneret orifices m which directly extrude and flow through and the spinneret orifices n which extrude and flow through after being distributed according to the parallel composite spinning mode are straight-line spinneret orifices, and the number ratio is 1: 10; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; the aspect ratio of the cross section of the spinneret hole m or the spinneret hole n is 13: 1; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode, the PET melt and the PBT melt are respectively extruded from two sides of a long symmetrical shaft of the cross section of the linear spinneret orifice;
the spinneret hole m is composed of a guide hole E, a transition hole and a capillary micropore which are connected in sequence, the spinneret hole n is composed of a guide hole D, a transition hole and a capillary micropore which are connected in sequence, the guide hole E is connected with the distribution hole A, and the guide hole D is simultaneously connected with the distribution hole B and the distribution hole C; the distribution holes A, B and C are positioned on the distribution plate in the spinning manifold III; the shunting is to convey the PET melt to the distribution hole A and the distribution hole B through the spinning manifold I, and simultaneously convey the PBT melt to the distribution hole C through the spinning manifold II; the temperature of the spinning manifold I is 280 ℃, the temperature of the spinning manifold II is 265 ℃ and the temperature of the spinning manifold III is 276 ℃; all the spinneret orifices are distributed in concentric circles, the spinneret orifices on the same circle are m or n, and the spinneret orifices on the circle at the outermost circle are n;
(2) preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the FDY process comprises the following parameters: the cooling temperature is 25 ℃, the one-roll speed is 2100m/min, the one-roll temperature is 70 ℃, the two-roll speed is 2960m/min, the two-roll temperature is 125 ℃, and the winding speed is 2910 m/min; the temperature of the relaxation heat treatment is 104 ℃, and the time is 30 min;
as shown in fig. 2, the prepared PBT/PET bicomponent elastic yarn consists of a PET monofilament with a straight-line cross section and a PBT/PET parallel composite monofilament with a straight-line cross section, wherein PBT and PET in the PBT/PET parallel composite monofilament are distributed on two sides of a long symmetrical axis of the straight line; the single filaments in the PBT/PET double-component elastic yarn are randomly distributed in the curling direction;
selecting the prepared PBT/PET double-component elastic wire with randomly distributed curling directions for testing, wherein the testing result shows that the elastic wire has a curling shrinkage rate of 54%, a curling stability of 85%, a contraction elongation of 95%, a curling radius of 0.0920mm, a curling elastic recovery rate of 93.4% and a thread pitch of 0.433 mm; the breaking strength was 3.4cN/dtex, the elongation at break was 35.0% and the total fineness was 130 dtex.
Comparative example 1
The preparation method of PBT/PET bicomponent elastic yarn has the same process as that of the embodiment 1, and the difference is that in the spinning, PET melt is not divided into two paths, but is distributed and extruded together with PBT melt in a parallel composite spinning mode; therefore, the prepared PBT/PET double-component elastic yarn does not contain in-line PET monofilament.
The PBT/PET double-component elastic yarns prepared in the comparative example 1 and the example 1 are respectively used for testing the uneven strip shade of two plain weave knitted fabrics by adopting a plain weave knitted fabric woven by a seamless forming circular knitting machine, and the testing process of each plain weave knitted fabric is as follows: firstly, acquiring a plain knitted fabric image, converting the plain knitted fabric image into a gray image, then performing primary processing and secondary processing on the gray image, and calculating a parameter D, and representing the uneven degree of the strip shadow shape by using the parameter D, wherein the gray image comprises a strip shadow area, a high gray value area of a non-strip shadow area and a low gray value area of the non-strip shadow area; the first processing is to change pixel points in a high gray value area of a non-bar-shadow area in a gray image into pure white points; the second processing is to change the pixel points of the low gray value area of the non-shadow area in the gray image into pure white points; the formula for the parameter D is: d ═ Σ B/a, where Σ B represents the number of pixels having a gray scale value of 0 in the grayscale image, and a represents the total number of pixels in the grayscale image.
The results obtained from the tests were: the D value of the plain woven fabric made of the PBT/PET bicomponent elastic yarn in example 1 was 0.9%; the D value of the plain weave fabric made of the PBT/PET bicomponent elastic yarn in the comparative example 1 was 19.2%; this shows that the uneven condition of the stripes in the plain weave knitted fabric woven by the PBT/PET bicomponent elastic yarn in example 1 is reduced because the PBT/PET parallel composite monofilament is replaced by a part of PET monofilament in example 1, thereby breaking the neat left and right spiral form of the pure PBT/PET bicomponent composite fiber; the curling form of each PBT/PET parallel composite monofilament is different from other fibers, and the condition of uneven strip shade on the cloth surface can not occur after the PBT/PET parallel composite monofilament is made into plain weave knitted fabric; the plain woven fabric made of the PBT/PET double-component elastic yarn in the comparative example 1 has a neat left and right spiral form, and the neat spiral form has uneven stripe shade on the cloth surface.
Comparative example 2
The preparation method of the PBT/PET double-component elastic yarn is basically the same as that in the embodiment 1, and the difference is that when the elastic yarn is distributed and extruded in a parallel composite spinning mode, PET melt and PBT melt are respectively extruded from two sides of a short symmetrical axis of the cross section of a linear spinneret orifice; therefore, the PBT/PET bicomponent elastic yarn has the crimp radius of 0.13mm and the crimp elastic recovery of 90.3 percent.
Comparative example 2 was compared with example 1It can be seen that the smaller the bending radius of the PBT/PET bicomponent elastic yarn obtained in example 1, the better the elastic properties of the fiber, because the direction in which the fiber is curled is along the direction in which the heat shrinkage rate is high, and thus the bending section modulus in example 1 is WxBending section modulus W in comparative example 2yAccording to the characteristics of the linear spinneret orifice: the length of the major axis y of the cross-section is much greater than the length of the minor axis x, W in comparative example 2yMuch greater than W in example 1xSince the radius of crimp of the fiber is larger as the flexural section modulus is larger, the radius of crimp is larger and the crimp elastic recovery is smaller in comparative example 1.
Example 2
A preparation method of PBT/PET double-component elastic yarn comprises the following steps:
(1) extruding PBT/PET double-component elastic yarns on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path of the melt is distributed together with the PBT melt in a parallel composite spinning mode and then extruded; wherein the intrinsic viscosity of the PET melt is 0.56dL/g, and the intrinsic viscosity of the PBT melt is 1.06 dL/g;
the spinneret orifices m which directly extrude and flow through and the spinneret orifices n which extrude and flow through after being distributed according to the parallel composite spinning mode are straight-line spinneret orifices, and the number ratio is 1: 5; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; the aspect ratio of the cross section of the spinneret hole m or spinneret hole n is 9: 1; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode, the PET melt and the PBT melt are respectively extruded from two sides of a long symmetrical axis of the cross section of the linear spinneret orifice;
the spinneret orifice m consists of a guide orifice E, a transition orifice and a capillary micropore which are connected in sequence, the spinneret orifice n consists of a guide orifice D, a transition orifice and a capillary micropore which are connected in sequence, the guide orifice E is connected with the distribution orifice A, and the guide orifice D is simultaneously connected with the distribution orifice B and the distribution orifice C; the distribution holes A, B and C are positioned on the distribution plate in the spinning manifold III; the shunting is to convey the PET melt to the distribution hole A and the distribution hole B through the spinning manifold I, and simultaneously convey the PBT melt to the distribution hole C through the spinning manifold II; the temperature of the spinning manifold I is 275 ℃, the temperature of the spinning manifold II is 261 ℃, and the temperature of the spinning manifold III is 270 ℃; all the spinneret holes are distributed in concentric circles, the spinneret holes in the same circle are m or n, and the spinneret holes in the circle of the outermost circle are n;
(2) preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the FDY process comprises the following parameters: the cooling temperature is 20 ℃, the first roller speed is 2150m/min, the first roller temperature is 80 ℃, the second roller speed is 2860m/min, the second roller temperature is 130 ℃, and the winding speed is 2730 m/min; the temperature of the relaxation heat treatment is 103 ℃, and the time is 28 min;
the prepared PBT/PET double-component elastic yarn consists of PET monofilaments with straight-line-shaped cross sections and PBT/PET parallel composite monofilaments with straight-line-shaped cross sections, wherein PBT and PET in the PBT/PET parallel composite monofilaments are distributed on two sides of a straight-line long symmetrical shaft; the single silk curling directions in the PBT/PET double-component elastic yarn are randomly distributed;
the prepared PBT/PET double-component elastic yarns with randomly distributed curling directions are selected for testing, and the test results are shown in Table 1.
Example 3
A preparation method of PBT/PET double-component elastic yarn comprises the following steps:
(1) extruding PBT/PET double-component elastic yarns on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path is distributed together with the PBT melt according to a parallel composite spinning mode and then extruded; wherein the intrinsic viscosity of the PET melt is 0.58dL/g, and the intrinsic viscosity of the PBT melt is 1.09 dL/g;
the spinneret orifices m directly extruding and flowing through and the spinneret orifices n extruding and flowing through after being distributed in a parallel composite spinning mode are in-line spinneret orifices, and the number ratio is 1: 8; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; the aspect ratio of the cross section of the spinneret hole m or the spinneret hole n is 13: 1; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode, the PET melt and the PBT melt are respectively extruded from two sides of a long symmetrical axis of the cross section of the linear spinneret orifice;
the spinneret hole m is composed of a guide hole E, a transition hole and a capillary micropore which are connected in sequence, the spinneret hole n is composed of a guide hole D, a transition hole and a capillary micropore which are connected in sequence, the guide hole E is connected with the distribution hole A, and the guide hole D is simultaneously connected with the distribution hole B and the distribution hole C; the distribution hole A, the distribution hole B and the distribution hole C are positioned on a distribution plate in the spinning beam III; the flow splitting is to convey the PET melt to the distribution hole A and the distribution hole B through the spinning manifold I, and simultaneously convey the PBT melt to the distribution hole C through the spinning manifold II; the temperature of the spinning manifold I is 276 ℃, the temperature of the spinning manifold II is 265 ℃, and the temperature of the spinning manifold III is 271 ℃; all the spinneret holes are distributed in concentric circles, the spinneret holes in the same circle are m or n, and the spinneret holes in the circle of the outermost circle are n;
(2) preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the FDY process comprises the following parameters: the cooling temperature is 21 ℃, the one-roll speed is 2100m/min, the one-roll temperature is 71 ℃, the two-roll speed is 2800m/min, the two-roll temperature is 126 ℃, and the winding speed is 2770 m/min; the temperature of the relaxation heat treatment is 120 ℃, and the time is 29 min;
the prepared PBT/PET double-component elastic yarn consists of PET monofilaments with straight-line-shaped cross sections and PBT/PET parallel composite monofilaments with straight-line-shaped cross sections, wherein PBT and PET in the PBT/PET parallel composite monofilaments are distributed on two sides of a straight-line long symmetrical shaft; the single silk curling directions in the PBT/PET double-component elastic yarn are randomly distributed;
the prepared PBT/PET double-component elastic yarns with randomly distributed curling directions are selected for testing, and the test results are shown in Table 1.
Example 4
A preparation method of PBT/PET double-component elastic yarn comprises the following steps:
(1) the PBT/PET double-component elastic yarns are extruded on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path is distributed together with the PBT melt according to a parallel composite spinning mode and then extruded; wherein the intrinsic viscosity of the PET melt is 0.53dL/g, and the intrinsic viscosity of the PBT melt is 1.00 dL/g;
the spinneret orifices m which directly extrude and flow through and the spinneret orifices n which extrude and flow through after being distributed according to the parallel composite spinning mode are straight-line spinneret orifices, and the number ratio is 1: 6; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; the aspect ratio of the cross section of the spinneret hole m or spinneret hole n is 13: 1; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode, the PET melt and the PBT melt are respectively extruded from two sides of a long symmetrical axis of the cross section of the linear spinneret orifice;
the spinneret hole m is composed of a guide hole E, a transition hole and a capillary micropore which are connected in sequence, the spinneret hole n is composed of a guide hole D, a transition hole and a capillary micropore which are connected in sequence, the guide hole E is connected with the distribution hole A, and the guide hole D is simultaneously connected with the distribution hole B and the distribution hole C; the distribution holes A, B and C are positioned on the distribution plate in the spinning manifold III; the flow splitting is to convey the PET melt to the distribution hole A and the distribution hole B through the spinning manifold I, and simultaneously convey the PBT melt to the distribution hole C through the spinning manifold II; the temperature of the spinning beam I is 279 ℃, the temperature of the spinning beam II is 260 ℃, and the temperature of the spinning beam III is 273 ℃; all the spinneret holes are distributed in concentric circles, the spinneret holes in the same circle are m or n, and the spinneret holes in the circle of the outermost circle are n;
(2) preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the FDY process comprises the following parameters: the cooling temperature is 23 ℃, the first-roller speed is 2050m/min, the first-roller temperature is 75 ℃, the two-roller speed is 3000m/min, the two-roller temperature is 128 ℃, and the winding speed is 2770 m/min; the temperature of the relaxation heat treatment is 90 ℃, and the time is 24 min;
the prepared PBT/PET double-component elastic yarn consists of PET monofilaments with straight-line-shaped cross sections and PBT/PET parallel composite monofilaments with straight-line-shaped cross sections, wherein PBT and PET in the PBT/PET parallel composite monofilaments are distributed on two sides of a straight-line long symmetrical shaft; the single silk curling directions in the PBT/PET double-component elastic yarn are randomly distributed;
the prepared PBT/PET double-component elastic yarns with randomly distributed curling directions are selected for testing, and the test results are shown in Table 1.
Example 5
A preparation method of PBT/PET double-component elastic yarn comprises the following steps:
(1) the PBT/PET double-component elastic yarns are extruded on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path of the melt is distributed together with the PBT melt in a parallel composite spinning mode and then extruded; wherein the intrinsic viscosity of the PET melt is 0.53dL/g, and the intrinsic viscosity of the PBT melt is 1.18 dL/g;
the spinneret orifices m directly extruding and flowing through and the spinneret orifices n extruding and flowing through after being distributed in a parallel composite spinning mode are in-line spinneret orifices, and the number ratio is 1: 7; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; the aspect ratio of the cross section of the spinneret hole m or spinneret hole n is 15: 1; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode, the PET melt and the PBT melt are respectively extruded from two sides of a long symmetrical shaft of the cross section of the linear spinneret orifice;
the spinneret orifice m consists of a guide orifice E, a transition orifice and a capillary micropore which are connected in sequence, the spinneret orifice n consists of a guide orifice D, a transition orifice and a capillary micropore which are connected in sequence, the guide orifice E is connected with the distribution orifice A, and the guide orifice D is simultaneously connected with the distribution orifice B and the distribution orifice C; the distribution holes A, B and C are positioned on the distribution plate in the spinning manifold III; the flow splitting is to convey the PET melt to the distribution hole A and the distribution hole B through the spinning manifold I, and simultaneously convey the PBT melt to the distribution hole C through the spinning manifold II; the temperature of the spinning manifold I is 280 ℃, the temperature of the spinning manifold II is 262 ℃, and the temperature of the spinning manifold III is 273 ℃; all the spinneret orifices are distributed in concentric circles, the spinneret orifices on the same circle are m or n, and the spinneret orifices on the circle at the outermost circle are n;
(2) preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the FDY process comprises the following parameters: the cooling temperature is 24 ℃, the one-roll speed is 2065m/min, the one-roll temperature is 72 ℃, the two-roll speed is 2980m/min, the two-roll temperature is 126 ℃, and the winding speed is 2770 m/min; the temperature of the relaxation heat treatment is 105 ℃, and the time is 25 min;
the prepared PBT/PET double-component elastic yarn consists of PET monofilaments with straight-line-shaped cross sections and PBT/PET parallel composite monofilaments with straight-line-shaped cross sections, wherein PBT and PET in the PBT/PET parallel composite monofilaments are distributed on two sides of a long symmetrical shaft of the straight line shape; the single filaments in the PBT/PET double-component elastic yarn are randomly distributed in the curling direction;
the prepared PBT/PET double-component elastic yarns with randomly distributed curling directions are selected for testing, and the test results are shown in Table 1.
Example 6
A preparation method of PBT/PET double-component elastic yarn comprises the following steps:
(1) the PBT/PET double-component elastic yarns are extruded on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path of the melt is distributed together with the PBT melt in a parallel composite spinning mode and then extruded; wherein the intrinsic viscosity of the PET melt is 0.54dL/g, and the intrinsic viscosity of the PBT melt is 1.18 dL/g;
the spinneret orifices m directly extruded and flowed through and the spinneret orifices n extruded and flowed through after being distributed in a parallel composite spinning mode are in-line spinneret orifices, and the number ratio is 1: 6; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; the aspect ratio of the cross section of the spinneret hole m or spinneret hole n is 18: 1; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode, the PET melt and the PBT melt are respectively extruded from two sides of a long symmetrical axis of the cross section of the linear spinneret orifice;
the spinneret orifice m consists of a guide orifice E, a transition orifice and a capillary micropore which are connected in sequence, the spinneret orifice n consists of a guide orifice D, a transition orifice and a capillary micropore which are connected in sequence, the guide orifice E is connected with the distribution orifice A, and the guide orifice D is simultaneously connected with the distribution orifice B and the distribution orifice C; the distribution holes A, B and C are positioned on the distribution plate in the spinning manifold III; the shunting is to convey the PET melt to the distribution hole A and the distribution hole B through the spinning manifold I, and simultaneously convey the PBT melt to the distribution hole C through the spinning manifold II; the temperature of the spinning beam I is 278 ℃, the temperature of the spinning beam II is 261 ℃, and the temperature of the spinning beam III is 275 ℃; all the spinneret orifices are distributed in concentric circles, the spinneret orifices on the same circle are m or n, and the spinneret orifices on the circle at the outermost circle are n;
(2) preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the FDY process comprises the following parameters: the cooling temperature is 25 ℃, the one-roll speed is 2000m/min, the one-roll temperature is 70 ℃, the two-roll speed is 2880m/min, the two-roll temperature is 125 ℃, and the winding speed is 2910 m/min; the temperature of the relaxation heat treatment is 104 ℃, and the time is 20 min;
the prepared PBT/PET double-component elastic yarn consists of PET monofilaments with straight-line-shaped cross sections and PBT/PET parallel composite monofilaments with straight-line-shaped cross sections, wherein PBT and PET in the PBT/PET parallel composite monofilaments are distributed on two sides of a long symmetrical shaft of the straight line shape; the single filaments in the PBT/PET double-component elastic yarn are randomly distributed in the curling direction;
the prepared PBT/PET double-component elastic yarns with randomly distributed curling directions are selected for testing, and the test results are shown in Table 1.
Example 7
A preparation method of PBT/PET double-component elastic yarn comprises the following steps:
(1) the PBT/PET double-component elastic yarns are extruded on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path of the melt is distributed together with the PBT melt in a parallel composite spinning mode and then extruded; wherein the intrinsic viscosity of the PET melt is 0.50dL/g, and the intrinsic viscosity of the PBT melt is 1.04 dL/g;
the spinneret orifices m directly extruded and flowed through and the spinneret orifices n extruded and flowed through after being distributed in a parallel composite spinning mode are in-line spinneret orifices, and the number ratio is 1: 6; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; the aspect ratio of the cross section of the spinneret hole m or spinneret hole n is 13: 1; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
when the PET melt with the temperature of 277 ℃ and the PBT melt with the temperature of 262 ℃ enter a spinning component and are respectively extruded from two sides of a long symmetry axis of the cross section of the linear spinneret orifice when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode;
all the spinneret holes are distributed in concentric circles, the spinneret holes in the same circle are m or n, and the spinneret holes in the circle of the outermost circle are n;
(2) preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the FDY process comprises the following parameters: the spinning temperature is 274 ℃, the cooling temperature is 24 ℃, the first-roller speed is 2200m/min, the first-roller temperature is 73 ℃, the second-roller speed is 2880m/min, the second-roller temperature is 128 ℃, and the winding speed is 2780 m/min; the temperature of the relaxation heat treatment is 114 ℃, and the time is 23 min;
the prepared PBT/PET double-component elastic yarn consists of PET monofilaments with straight-line-shaped cross sections and PBT/PET parallel composite monofilaments with straight-line-shaped cross sections, wherein PBT and PET in the PBT/PET parallel composite monofilaments are distributed on two sides of a straight-line long symmetrical shaft; the single silk curling directions in the PBT/PET double-component elastic yarn are randomly distributed;
the prepared PBT/PET double-component elastic yarns with randomly distributed curling directions are selected for testing, and the test results are shown in Table 1.
Example 8
A preparation method of PBT/PET double-component elastic yarn comprises the following steps:
(1) extruding PBT/PET double-component elastic yarns on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path of the melt is distributed together with the PBT melt in a parallel composite spinning mode and then extruded; wherein the intrinsic viscosity of the PET melt is 0.51dL/g, and the intrinsic viscosity of the PBT melt is 1.18 dL/g;
the spinneret orifices m which directly extrude and flow through and the spinneret orifices n which extrude and flow through after being distributed according to the parallel composite spinning mode are straight-line spinneret orifices, and the number ratio is 1: 6; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; the aspect ratio of the cross section of the spinneret hole m or spinneret hole n is 14: 1; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
when the PET melt with the temperature of 279 ℃ and the PBT melt with the temperature of 262 ℃ enter a spinning assembly and are respectively extruded from two sides of a long symmetry axis of the cross section of the linear spinneret orifice when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode;
all the spinneret orifices are distributed in concentric circles, the spinneret orifices on the same circle are m or n, and the spinneret orifices on the circle at the outermost circle are n;
(2) preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns; the FDY process comprises the following parameters: the spinning temperature is 270 ℃, the cooling temperature is 20 ℃, the first roller speed is 2180m/min, the first roller temperature is 75 ℃, the second roller speed is 2900m/min, the second roller temperature is 129 ℃, and the winding speed is 2760 m/min; the temperature of the relaxation heat treatment is 101 ℃, and the time is 29 min;
the prepared PBT/PET double-component elastic yarn consists of PET monofilaments with straight-line-shaped cross sections and PBT/PET parallel composite monofilaments with straight-line-shaped cross sections, wherein PBT and PET in the PBT/PET parallel composite monofilaments are distributed on two sides of a long symmetrical shaft of the straight line shape; the single filaments in the PBT/PET double-component elastic yarn are randomly distributed in the curling direction;
the prepared PBT/PET double-component elastic yarns with randomly distributed curling directions are selected for testing, and the test results are shown in Table 1.
TABLE 1
Figure BDA0002334462660000131
Figure BDA0002334462660000141

Claims (6)

1. A preparation method of PBT/PET double-component elastic yarn is characterized by comprising the following steps: the PBT/PET double-component elastic yarns are extruded on the same spinneret plate;
splitting the PET melt into two paths: one path is directly extruded after being distributed; the other path is distributed together with the PBT melt according to a parallel composite spinning mode and then extruded;
the spinneret orifices m for direct flow extrusion and the spinneret orifices n for flow extrusion after being distributed in a parallel composite spinning mode are linear spinneret orifices, and the number ratio of the spinneret orifices m to the spinneret orifices n is 1: 5-10; the ratio of the equivalent diameter of the spinneret orifice m to the equivalent diameter of the spinneret orifice n is 1: 1; all the spinneret orifices are distributed in concentric circles, the spinneret orifices on the same circle are m or n, and the spinneret orifices on the circle at the outermost circle are n;
the spinneret orifice m is composed of a guide hole E, a transition hole and a capillary micropore which are connected in sequence, the spinneret orifice n is composed of a guide hole D, a transition hole and a capillary micropore which are connected in sequence, the guide hole E is connected with the distribution hole A, and the guide hole D is simultaneously connected with the distribution hole B and the distribution hole C; the distribution hole A, the distribution hole B and the distribution hole C are positioned on a distribution plate in the spinning beam III; the shunting is to convey the PET melt to the distribution hole A and the distribution hole B through the spinning manifold I, and simultaneously convey the PBT melt to the distribution hole C through the spinning manifold II;
when the PET melt and the PBT melt are extruded after being distributed in a parallel composite spinning mode, the PET melt and the PBT melt are respectively extruded from two sides of a long symmetrical axis of the cross section of the linear spinneret orifice; the mass ratio of the PET melt passing through the spinneret orifice n to the PBT melt is 50: 50;
preparing FDY yarns according to an FDY process after extrusion, and then performing relaxation heat treatment to obtain PBT/PET double-component elastic yarns;
the PBT/PET double-component elastic yarn consists of a PET monofilament with a straight-line cross section and a PBT/PET parallel composite monofilament with a straight-line cross section, wherein PBT and PET in the PBT/PET parallel composite monofilament are distributed on two sides of a long symmetrical shaft of the straight line; the single silk curling directions of the PBT/PET double-component elastic silk are randomly distributed.
2. The preparation method of the PBT/PET bicomponent elastic yarn according to claim 1, wherein the aspect ratio of the cross section of a spinneret orifice m or a spinneret orifice n is 9-18: 1.
3. The preparation method of the PBT/PET bicomponent elastic yarn according to claim 1, wherein the parameters of the FDY process are as follows: the cooling temperature is 20-25 ℃, the first-roller speed is 2000-2200 m/min, the first-roller temperature is 70-80 ℃, the second-roller speed is 2800-3000 m/min, the second-roller temperature is 125-130 ℃, and the winding speed is 2730-2910 m/min; the temperature of the relaxation heat treatment is 90-120 ℃, and the time is 20-30 min.
4. The preparation method of the PBT/PET bicomponent elastic yarn according to claim 3, wherein the intrinsic viscosity of the PET melt is 0.50-0.58 dL/g, the temperature of a spinning manifold I is 275-280 ℃, the intrinsic viscosity of the PBT melt is 1.00-1.20 dL/g, the temperature of a spinning manifold II is 260-265 ℃, and the temperature of a spinning manifold III is 270-276 ℃.
5. The preparation method of the PBT/PET bicomponent elastic yarn according to claim 1, wherein the PBT/PET bicomponent elastic yarn has a crimp shrinkage of 52-56%, a crimp stability of 83-88%, a compression elongation of 93-97%, a crimp radius of 0.0786-0.103 mm, a crimp elastic recovery of 92.5-97.6%, and a thread pitch of 0.109-0.784 mm.
6. The preparation method of the PBT/PET double-component elastic yarn according to claim 1, wherein the PBT/PET double-component elastic yarn has a breaking strength of not less than 3.0cN/dtex, an elongation at break of 35.0 +/-3.5% and a total fineness of 75-150 dtex.
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