WO2021135080A1

WO2021135080A1 - Composite crimped fiber for knitting and preparation method therefor

Info

Publication number: WO2021135080A1
Application number: PCT/CN2020/095604
Authority: WO
Inventors: 范红卫; 王山水; 王丽丽; 汤方明
Original assignee: 江苏恒力化纤股份有限公司
Priority date: 2019-12-29
Filing date: 2020-06-11
Publication date: 2021-07-08
Also published as: CN110983467B; KR20220021478A; JP7234467B2; CN110983467A; JP2022552439A; KR102516295B1

Abstract

A composite crimped fiber for knitting and a preparation method therefor. In a process of preparing a circular side-by-side composite fiber from PET and PBT according to FDY processing, spinneret holes on a spinneret plate are changed from a circular shape to a trilobal shape, cyclical blowing is used for cooling, the distribution of trilobal spinneret holes on the spinneret plate is controlled to satisfy a certain condition, and relaxation thermal treatment is performed on fibers to obtain a composite crimped fiber for knitting. The contact surfaces of the PET and the PBT when flowing through guide holes of the trilobal spinneret holes are parallel to one another. The prepared composite crimped fiber for knitting takes a three-dimensional crimped form and consists of a plurality of PET/PBT side-by-side composite monofilaments having trilobal cross-sections.

Description

Composite crimped fiber for knitting and preparation method thereof

Technical field

The invention belongs to the technical field of polyester fibers, and relates to a composite crimped fiber for knitting and a preparation method thereof.

Background technique

For chemical fibers, the properties of fibers made from different polymer raw materials are completely different, each with its own advantages and disadvantages. Because of this, more and more products are made by combining different fiber properties to give full play to their respective advantages. Advantages. Among them, the side-by-side two-component composite fiber uses the difference in thermal shrinkage properties of the two components to cause the fiber to bend away from the fiber axis, presenting a permanent three-dimensional spiral crimp, and obtain a crimp similar to wool fiber. This kind of crimp has the characteristics of long-lasting stability and good elasticity, which can give the fabric better elasticity, bulkiness and coverage, and is widely used in clothing. However, polyester two-component composite fiber requires high preparation technology, mainly because the flow state of the polymer melt in the spinneret hole should be controlled properly; and the characteristic of the prepared composite yarn is crimp elasticity, which absorbs moisture and wicks sweat. The performance has not been significantly improved, but because the polyester two-component composite fiber is widely used in knitted fabrics, it is necessary to further improve its moisture absorption and perspiration performance.

Therefore, it is of great significance to study a three-dimensional self-crimping polyester composite fiber with good moisture absorption and perspiration performance.

Summary of the invention

The invention provides a composite crimped fiber for knitting and a preparation method thereof; the purpose is to solve the problem of insufficient moisture absorption and moisture conduction performance of the polyester composite fiber in the prior art.

In order to achieve the above objective, the scheme adopted by the present invention is as follows:

A method for preparing composite crimped fibers for knitting. In the process of preparing circular side-by-side composite fibers from PET and PBT according to the FDY process, the spinneret holes on the spinneret are changed from circular to trilobal, and ring blowing is used. Cool, and control the arrangement of the trilobal spinneret holes on the spinneret to meet certain conditions to obtain FDY filaments, and perform relaxation heat treatment on the FDY filaments to obtain composite crimped fibers for knitting (the present invention prepares trilobal parallel composite fibers using The spinning component is based on the spinning component used in the preparation of circular sheath-core composite fibers with the prior art, and the difference is only in the shape of the spinneret hole);

The ratio of the length of the three leaves of the same trilobe spinneret is 1.0:1.1～1.4:2.0～2.5, the corresponding ratio of the width of the three leaves is 1.5:1.5:1, and the ratio of the length to the width of the shortest leaf is 2.5 ~3.5:1, the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

A certain condition is: taking the centerline of the longest leaf of any trilobal spinneret as the reference line, all other trilobal spinnerets are divided into two types, the centerline of the longest leaf of one type is parallel to the reference line; The center line of the longest leaf of the other type is orthogonal to the reference line; the number of the two types of trilobal spinneret holes is equal;

The contact surfaces of PET and PBT when flowing in the guide holes of each trilobal spinneret are parallel to each other (because the apparent viscosities of PET and PBT are close in the guide holes of the trilobal spinneret, the contact surfaces of the two Approximately flat).

As a preferred technical solution:

In the method for preparing composite crimped fibers for knitting as described above, the mass ratio of PET to PBT is 30:70 to 70:30.

The method for preparing composite crimped fiber for knitting as described above, the intrinsic viscosity of PET is 0.50～0.58dL/g, the temperature of the spinning box corresponding to PET is 275～280℃, and the intrinsic viscosity of PBT is 1.10～1.21 dL/g, the temperature of the spinning box corresponding to PBT is 260～265℃.

For the preparation method of composite crimped fiber for knitting as described above, the parameters of FDY process are: spinning temperature 274～277℃, cooling temperature 20～25℃, network pressure 0.20～0.30MPa, one roll speed 2000～2200m/ min, the temperature of one roll is 75～85℃, the speed of two rolls is 3300～3600m/min, the temperature of two rolls is 135～145℃, and the winding speed is 3230～3510m/min.

In the method for preparing composite crimped fibers for knitting as described above, the temperature of the relaxation heat treatment is 90-120°C and the time is 20-30 minutes.

The present invention also provides a composite crimped fiber for knitting prepared by the method for preparing a composite crimped fiber for knitting as described in any one of the above, which has a three-dimensional crimped form and is composed of a plurality of PET/PBT with a trilobal cross section. Composed of juxtaposed composite monofilaments, make an imaginary line that intersects the trilobal shape. The trilobal shape is divided into two parallel parts by the imaginary line, one part corresponds to PET and the other part corresponds to PBT.

As a preferred technical solution:

For the composite crimped fiber for knitting as described above, the crimp shrinkage rate of the composite crimped fiber for knitting is 50 to 54%, the crimp stability is 82 to 85%, and the shrinkage elongation is 94 to 98 according to GB/T6506-2001. %, the crimp elastic recovery rate is 94-97%.

For the composite crimped fiber for knitting as described above, the breaking strength of the composite crimped fiber for knitting is ≥2.8 cN/dtex, the elongation at break is 43.0±3.0%, and the total fineness is 70-200 dtex.

The principle of the present invention is as follows:

The composite crimped fiber for knitting in the present invention is prepared according to the FDY process. PET and PBT are extruded from the trilobal spinneret on the same spinneret. In the parallel composite spinning of the present invention, PET and PBT The contact surfaces when flowing in the guide holes of each trilobal spinneret are parallel to each other (the apparent viscosities of PET and PBT are close, and the contact surfaces of the two are approximately flat), and a boundary is formed between the two different melts Since the center line of the longest leaf of one type of the three-lobed spinneret is parallel to the reference line; the center line of the longest leaf of the other type is orthogonal to the reference line, from different nozzles on the same spinneret. The monofilaments extruded in the filament holes are different. This difference is specifically: during the spinning process, the spinning pressure and the melt mass ratio are constant, and the melt mass ratio in each spinneret hole is the same. However, because the direction of the longest leaf in the trilobal shape is different from the angle between the boundary line of the different melts in the guide hole, it will cause the contact surface area of the different melts in different monofilaments to be different (that is, make one and An imaginary line intersecting a trilobal shape. The trilobal shape is divided into two parallel parts by the imaginary line. One part corresponds to PET and the other part corresponds to PBT. In the cross section, the size of the contact surface of the two parts is different), which leads to when the yarn is in After heat treatment, due to the difference in thermal shrinkage of PET and PBT, the composite crimped fiber for knitting has a three-dimensional crimp shape;

Since a single fiber presents a special-shaped cross-section (trilobal) structure, this kind of grooved fiber will give the fabric good moisture absorption and moisture conductivity (the wicking effect of the capillary produced by the groove), especially when it has grooves. When the fiber is self-crimping, the same groove is turned from the inside to the outside, and the part that first absorbs moisture will be turned over to the other side by the outlet of the groove. Compared with the special-shaped cross-section fiber in the prior art (single The grooves of the root fibers usually face the same side), therefore, the moisture absorption and moisture transmission efficiency of the composite crimped fiber for knitting of the present invention will be higher.

Beneficial effect

(1) The method for preparing composite crimped fiber for knitting of the present invention adopts trilobal spinneret and the arrangement relationship between the melt contact surface of PET and PBT in the guide hole, and the composite crimped fiber is prepared The size of the contact surface between the two components in different monofilaments is different;

(2) The composite crimped fiber for knitting of the present invention has a three-dimensional crimped shape due to the different contact surfaces of different melts on the cross-section of different monofilaments;

(3) The composite crimped fiber for knitting of the present invention is a special-shaped cross-section fiber and is three-dimensionally self-crimped at the same time, so that the grooves are turned over and show better moisture absorption and perspiration performance.

Description of the drawings

Figure 1 is a schematic diagram of the shape of the trilobal spinneret of the present invention;

Fig. 2 is a schematic diagram of the distribution of the spinneret holes on the spinneret of the present invention.

Detailed ways

The present invention will be further explained below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Figure 1 is a schematic diagram of the shape of the trilobal spinneret and the distribution of the spinneret on the spinneret of the present invention. As shown in Figures 1 and 2, the spinneret on the spinneret is trilobal, the same The ratio of the length of the three leaves of the trilobe spinneret is 1.0:1.1～1.4:2.0～2.5, the corresponding ratio of the width of the three leaves is 1.5:1.5:1, and the ratio of the length to the width of the shortest leaf is 2.5～3.5 :1. The angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different trilobal spinneret holes are the same; and the arrangement of the trilobal spinneret holes on the spinneret is controlled as : Taking the centerline of the longest leaf of any trilobal spinneret as the reference line, all other trilobal spinnerets are divided into two types, the centerline of the longest leaf of one type is parallel to the reference line; the other type The center line of the longest leaf is orthogonal to the reference line; the number of the two types of trilobal spinneret holes is equal.

Fig. 1 and Fig. 2 are for illustration only, and not as a limitation to the present invention.

Example 1

A method for preparing composite crimped fibers for knitting, the process is as follows:

(1) FDY yarn is prepared from PET (intrinsic viscosity of 0.54dL/g) and PBT (intrinsic viscosity of 1.16dL/g) with a mass ratio of 55:45 according to the FDY process and the spinning process of circular parallel composite fiber. Change the spinneret hole on the spinneret from round to trilobal. The length ratio of the three leaves of the same trilobal spinneret is 1.0:1.1:2.0, and the corresponding three-lobe width ratio is 1.5: 1.5:1, the ratio of the length to the width of the shortest leaf is 2.7:1, and the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

Adopt ring blowing to cool, and control the arrangement of the trilobal spinneret on the spinneret to meet certain conditions. The certain condition is: take the centerline of the longest leaf of any trilobal spinneret as the reference line, and all others The three-lobed spinneret is divided into two types, the center line of the longest leaf of one type is parallel to the reference line; the center line of the longest leaf of the other type is orthogonal to the reference line; the two types of trilobal spinneret Equal number

The contact surfaces of PET and PBT are parallel to each other when they flow in the guide holes of each trilobal spinneret;

The parameters of the FDY process are: spinning temperature 275°C, PET corresponding spinning box temperature 279°C, PBT corresponding spinning box temperature 262°C, cooling temperature 21°C, network pressure 0.3MPa, one roll The speed is 2190m/min, the temperature of the first roll is 77°C, the speed of the second roll is 3340m/min, the temperature of the second roll is 135°C, and the winding speed is 3270m/min;

(2) Perform relaxation heat treatment on FDY yarn at a temperature of 104°C and a time of 27 minutes to obtain composite crimped fibers for knitting;

The prepared composite crimped fiber for knitting has a three-dimensional crimp shape, and is composed of multiple PET/PBT side-by-side composite monofilaments with a trilobal shape in cross section. An imaginary thread intersecting the trilobal shape is formed. The trilobal shape is imaginary thread Divided into two parallel parts, one part corresponds to PET and the other part corresponds to PBT; the crimp shrinkage rate of the composite crimped fiber for knitting is 52%, the crimp stability is 83%, the shrinkage elongation rate is 96%, and the crimp elastic recovery rate It is 96%; the breaking strength of the composite crimped fiber for knitting is 2.8 cN/dtex, the elongation at break is 46%, and the monofilament fineness is 1.13 dtex.

Example 2

(1) FDY yarn is prepared from PET (intrinsic viscosity of 0.5dL/g) and PBT (intrinsic viscosity of 1.19dL/g) with a mass ratio of 40:60 according to the FDY process and the spinning process of circular parallel composite fiber. Change the spinneret hole on the spinneret from round to trilobal, the length ratio of the three leaves of the same trilobal spinneret is 1.0:1.2:2.2, and the corresponding three-lobe width ratio is 1.5: 1.5:1, the ratio of the length to the width of the shortest leaf is 3.5:1, and the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

The parameters of the FDY process are: spinning temperature 274°C, PET corresponding spinning box temperature 275°C, PBT corresponding spinning box temperature 265°C, cooling temperature 20°C, network pressure 0.2MPa, one roll The speed is 2150m/min, the temperature of the first roll is 76°C, the speed of the second roll is 3360m/min, the temperature of the second roll is 141°C, and the winding speed is 3290m/min;

(2) Perform relaxation heat treatment on the FDY yarn at a temperature of 120°C and a time of 26 minutes to obtain composite crimped fibers for knitting;

The prepared composite crimped fiber for knitting has a three-dimensional crimp shape, and is composed of multiple PET/PBT side-by-side composite monofilaments with a trilobal shape in cross section. An imaginary thread intersecting the trilobal shape is formed. The trilobal shape is imaginary thread Divided into two parallel parts, one part corresponds to PET and the other part corresponds to PBT; the crimp shrinkage rate of the composite crimped fiber for knitting is 54%, the crimp stability is 85%, the shrinkage elongation rate is 94%, and the crimp elastic recovery rate It is 94%; the breaking strength of the composite crimped fiber for knitting is 2.8 cN/dtex, the elongation at break is 43%, and the monofilament fineness is 1 dtex.

Example 3

(1) FDY yarn is prepared from PET (intrinsic viscosity of 0.5dL/g) and PBT (intrinsic viscosity of 1.1dL/g) with a mass ratio of 30:70 according to the FDY process and the spinning process of circular parallel composite fibers. Change the spinneret hole on the spinneret from round to trilobal. The length ratio of the three leaves of the same trilobal spinneret is 1.0:1.4:2.5, and the corresponding three-lobe width ratio is 1.5: 1.5:1, the ratio of the length to the width of the shortest leaf is 2.5:1, and the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

The parameters of the FDY process are: spinning temperature 274°C, PET corresponding spinning box temperature 275°C, PBT corresponding spinning box temperature 260°C, cooling temperature 20°C, network pressure 0.2MPa, one roll The speed is 2000m/min, the temperature of the first roll is 75℃, the speed of the second roll is 3300m/min, the temperature of the second roll is 135℃, and the winding speed is 3230m/min;

(2) Perform relaxation heat treatment on the FDY yarn at a temperature of 90°C and a time of 30 minutes to obtain a composite crimped fiber for knitting;

The prepared composite crimped fiber for knitting has a three-dimensional crimp shape, and is composed of multiple PET/PBT side-by-side composite monofilaments with a trilobal shape in cross section. An imaginary thread intersecting the trilobal shape is formed. The trilobal shape is imaginary thread Divided into two parallel parts, one part corresponds to PET and the other part corresponds to PBT; the crimp shrinkage rate of the composite crimped fiber for knitting is 54%, the crimp stability is 82%, the shrinkage elongation rate is 94%, and the crimp elastic recovery rate It is 94%; the breaking strength of the composite crimped fiber for knitting is 2.91 cN/dtex, the elongation at break is 42%, and the monofilament fineness is 1.96 dtex.

Example 4

(1) FDY filaments are prepared from PET (intrinsic viscosity of 0.53dL/g) and PBT (intrinsic viscosity of 1.16dL/g) with a mass ratio of 70:30 according to the FDY process and the spinning process of circular parallel composite fibers. Change the spinneret hole on the spinneret from round to trilobal. The length ratio of the three leaves of the same trilobal spinneret is 1.0:1.3:2.5, and the corresponding three-lobe width ratio is 1.5: 1.5:1, the ratio of the length to the width of the shortest leaf is 2.6:1, and the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

The parameters of the FDY process are: spinning temperature 274°C, PET corresponding spinning box temperature 278°C, PBT corresponding spinning box temperature 261°C, cooling temperature 21°C, network pressure 0.2MPa, one roll The speed is 2200m/min, the temperature of the first roll is 83°C, the speed of the second roll is 3550m/min, the temperature of the second roll is 145°C, and the winding speed is 3480m/min;

(2) Perform relaxation heat treatment on the FDY yarn at a temperature of 113°C and a time of 27 minutes to obtain composite crimped fibers for knitting;

The prepared composite crimped fiber for knitting has a three-dimensional crimp shape, and is composed of multiple PET/PBT side-by-side composite monofilaments with a trilobal shape in cross section. An imaginary thread intersecting the trilobal shape is formed. The trilobal shape is imaginary thread Divided into two parallel parts, one part corresponds to PET and the other part corresponds to PBT; the crimp shrinkage rate of the composite crimped fiber for knitting is 50%, the crimp stability is 83%, the shrinkage elongation is 95%, and the crimp elastic recovery rate It is 95%; the breaking strength of the composite crimped fiber for knitting is 2.98 cN/dtex, the elongation at break is 42%, and the monofilament fineness is 1.33 dtex.

Example 5

(1) FDY yarn is prepared from PET (intrinsic viscosity of 0.56dL/g) and PBT (intrinsic viscosity of 1.15dL/g) with a mass ratio of 60:40 according to the FDY process and the spinning process of circular parallel composite fibers. Change the spinneret hole on the spinneret from round to trilobal. The length ratio of the three leaves of the same trilobal spinneret is 1.0:1.1:2.5, and the corresponding three-lobe width ratio is 1.5: 1.5:1, the ratio of the length to the width of the shortest leaf is 3.1:1, and the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

The parameters of the FDY process are: spinning temperature of 276°C, the temperature of the spinning box corresponding to PET is 279°C, the temperature of the spinning box corresponding to PBT is 261°C, the cooling temperature is 23°C, the network pressure is 0.3MPa, one roll The speed is 2050m/min, the temperature of the first roll is 78°C, the speed of the second roll is 3430m/min, the temperature of the second roll is 140°C, and the winding speed is 3360m/min;

(2) Perform relaxation heat treatment on the FDY yarn at a temperature of 114°C and a time of 27 minutes to obtain a composite crimped fiber for knitting;

The prepared composite crimped fiber for knitting has a three-dimensional crimp shape, and is composed of multiple PET/PBT side-by-side composite monofilaments with a trilobal shape in cross section. An imaginary thread intersecting the trilobal shape is formed. The trilobal shape is imaginary thread It is divided into two parts side by side, one part corresponds to PET, the other part corresponds to PBT; the crimp shrinkage rate of the composite crimped fiber for knitting is 50%, the crimp stability is 85%, the shrinkage elongation is 97%, and the crimp elastic recovery rate It is 97%; the breaking strength of the composite crimped fiber for knitting is 2.99 cN/dtex, the elongation at break is 41%, and the monofilament fineness is 1.35 dtex.

Example 6

(1) FDY filaments are prepared from PET (intrinsic viscosity of 0.52dL/g) and PBT (intrinsic viscosity of 1.11dL/g) with a mass ratio of 40:60 according to the FDY process and the spinning process of circular parallel composite fibers. The spinneret hole on the spinneret is changed from round to trilobal. The length ratio of the three leaves of the same trilobal spinneret is 1.0:1.4:2.0, and the corresponding three-lobe width ratio is 1.5: 1.5:1, the ratio of the length to the width of the shortest leaf is 2.5:1, and the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

The parameters of the FDY process are: spinning temperature 274°C, PET corresponding spinning box temperature 277°C, PBT corresponding spinning box temperature 260°C, cooling temperature 22°C, network pressure 0.3MPa, one roll The speed is 2060m/min, the temperature of the first roll is 83°C, the speed of the second roll is 3460m/min, the temperature of the second roll is 136°C, and the winding speed is 3390m/min;

(2) Perform relaxation heat treatment on FDY yarn at a temperature of 102°C and a time of 28 minutes to obtain composite crimped fibers for knitting;

The prepared composite crimped fiber for knitting has a three-dimensional crimp shape, and is composed of multiple PET/PBT side-by-side composite monofilaments with a trilobal shape in cross section. An imaginary thread intersecting the trilobal shape is formed. The trilobal shape is imaginary thread Divided into two parallel parts, one part corresponds to PET and the other part corresponds to PBT; the crimp shrinkage rate of the composite crimped fiber for knitting is 53%, the crimp stability is 82%, the shrinkage elongation rate is 94%, and the crimp elastic recovery rate It is 94%; the breaking strength of the composite crimped fiber for knitting is 2.99 cN/dtex, the elongation at break is 40%, and the monofilament fineness is 2 dtex.

Example 7

(1) FDY filaments are prepared from PET (intrinsic viscosity of 0.58dL/g) and PBT (intrinsic viscosity of 1.21dL/g) with a mass ratio of 70:30 according to the FDY process and the spinning process of circular parallel composite fibers. Change the spinneret on the spinneret from round to trilobal, the length ratio of the three leaves of the same trilobal spinneret is 1.0:1.2:2.4, and the corresponding three-lobe width ratio is 1.5: 1.5:1, the ratio of the length to the width of the shortest leaf is 3.5:1, and the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

The parameters of the FDY process are: spinning temperature of 277°C, the temperature of the spinning box corresponding to PET is 280°C, the temperature of the spinning box corresponding to PBT is 265°C, the cooling temperature is 25°C, the network pressure is 0.3MPa, one roll The speed is 2200m/min, the temperature of the first roll is 85°C, the speed of the second roll is 3600m/min, the temperature of the second roll is 145°C, and the winding speed is 3510m/min;

(2) Perform relaxation heat treatment on the FDY yarn at a temperature of 120°C and a time of 20 minutes to obtain a composite crimped fiber for knitting;

The prepared composite crimped fiber for knitting has a three-dimensional crimp shape, and is composed of multiple PET/PBT side-by-side composite monofilaments with a trilobal shape in cross section, and an imaginary thread intersecting the trilobal shape is made. It is divided into two parts side by side, one part corresponds to PET, the other part corresponds to PBT; the crimp shrinkage rate of the composite crimped fiber for knitting is 50%, the crimp stability is 85%, the shrinkage elongation rate is 98%, and the crimp elastic recovery rate It is 98%; the breaking strength of the composite crimped fiber for knitting is 3 cN/dtex, the elongation at break is 40%, and the monofilament fineness is 1 dtex.

Example 8

(1) FDY yarn is prepared from PET (intrinsic viscosity of 0.56dL/g) and PBT (intrinsic viscosity of 1.18dL/g) with a mass ratio of 35:65 according to the FDY process and the spinning process of circular parallel composite fibers. Change the spinneret hole on the spinneret from round to trilobal. The length ratio of the three leaves of the same trilobal spinneret is 1.0:1.3:2.5, and the corresponding three-lobe width ratio is 1.5: 1.5:1, the ratio of the length to the width of the shortest leaf is 3.2:1, and the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

The parameters of the FDY process are: spinning temperature of 277°C, the temperature of the spinning box corresponding to PET is 280°C, the temperature of the spinning box corresponding to PBT is 265°C, the cooling temperature is 21°C, the network pressure is 0.2MPa, one roll The speed is 2060m/min, the temperature of the first roll is 80°C, the speed of the second roll is 3510m/min, the temperature of the second roll is 142°C, and the winding speed is 3440m/min;

(2) Perform relaxation heat treatment on the FDY yarn at a temperature of 100°C and a time of 29 minutes to obtain composite crimped fibers for knitting;

The prepared composite crimped fiber for knitting has a three-dimensional crimp shape, and is composed of multiple PET/PBT side-by-side composite monofilaments with a trilobal shape in cross section, and an imaginary thread intersecting the trilobal shape is made. Divided into two parallel parts, one part corresponds to PET, the other part corresponds to PBT; the crimp shrinkage rate of the composite crimped fiber for knitting is 54%, the crimp stability is 82%, the shrinkage elongation is 97%, and the crimp elastic recovery rate It is 97%; the breaking strength of the composite crimped fiber for knitting is 3.08 cN/dtex, the elongation at break is 40%, and the monofilament fineness is 2 dtex.

Claims

A method for preparing composite crimped fibers for knitting, which is characterized in that: in the process of preparing circular parallel composite fibers from PET and PBT according to the FDY process, the spinneret holes on the spinneret are changed from circular to trilobal. , Adopt ring blowing to cool, and control the arrangement of the trilobal spinneret holes on the spinneret to meet certain conditions to prepare FDY yarn, and perform relaxation heat treatment on the FDY yarn to obtain composite crimped fiber for knitting;

The ratio of the length of the three leaves of the same trilobe spinneret is 1.0:1.1～1.4:2.0～2.5, the corresponding ratio of the width of the three leaves is 1.5:1.5:1, and the ratio of the length to the width of the shortest leaf is 2.5 ~3.5:1, the angle between the center lines of two adjacent leaves is 120°; the shape and size of the three leaves of different three-lobe spinnerets are the same;

A certain condition is: taking the centerline of the longest leaf of any trilobal spinneret as the reference line, all other trilobal spinnerets are divided into two types, the centerline of the longest leaf of one type is parallel to the reference line; The center line of the longest leaf of the other type is orthogonal to the reference line; the number of the two types of trilobal spinneret holes is equal;

The contact surfaces of PET and PBT are parallel to each other when they flow in the guide holes of each trilobal spinneret.
The method for preparing composite crimped fibers for knitting according to claim 1, wherein the mass ratio of PET to PBT is 30:70 to 70:30.
The method for preparing composite crimped fibers for knitting according to claim 2, wherein the intrinsic viscosity of PET is 0.50～0.58dL/g, the temperature of the spinning box corresponding to PET is 275～280℃, and the temperature of PBT is 275～280℃. The intrinsic viscosity of PBT is 1.10～1.21dL/g, and the temperature of the spinning box corresponding to PBT is 260～265℃.
The method for preparing composite crimped fibers for knitting according to claim 3, characterized in that the parameters of the FDY process are: spinning temperature 274～277℃, cooling temperature 20～25℃, network pressure 0.20～0.30MPa, The speed of one roll is 2000-2200m/min, the temperature of one roll is 75-85°C, the speed of two rolls is 3300-3600m/min, the temperature of two rolls is 135-145°C, and the winding speed is 3230-3510m/min.
The method for preparing composite crimped fibers for knitting according to claim 1, wherein the temperature of the relaxation heat treatment is 90-120°C and the time is 20-30 minutes.
The composite crimped fiber for knitting prepared by using the method for preparing composite crimped fiber for knitting according to any one of claims 1 to 5 is characterized in that it has a three-dimensional crimped form and is composed of a plurality of three-lobed cross-sections. Shaped PET/PBT side-by-side composite monofilament is composed of an imaginary line intersecting the trilobal shape. The trilobal shape is divided into two parallel parts by the imaginary line, one part corresponds to PET, and the other part corresponds to PBT.
The composite crimped fiber for knitting according to claim 6, wherein the crimp shrinkage rate of the composite crimped fiber for knitting is 50 to 54%, the crimp stability is 82 to 85%, and the shrinkage elongation is 94 to 98%. , Crimping elastic recovery rate is 94-97%.
The composite crimped fiber for knitting according to claim 6, wherein the breaking strength of the composite crimped fiber for knitting is ≥2.8 cN/dtex, the elongation at break is 43.0±3.0%, and the total fineness is 70-200 dtex.