Efficient preparation method of anti-pilling medium-high-strength low-boiling-shrinkage chinlon FDY (Fully Drawn Yarn) fiber

Abstract

The invention discloses an efficient preparation method of anti-pilling medium-high-strength low-boiling-shrinkage chinlon FDY fibers. The efficient preparation method comprises the following steps that S1, in-situ polymerization chinlon slices are prepared, extracted and dried; s2, the in-situ polymerization chinlon slices obtained in the step S1 are melted through a screw extruder to obtain melt, and nitrogen protection is adopted in the process; s3, the melt is evenly distributed to a spinning manifold through a distribution pipe and sprayed out through a high-pressure filtering assembly to form nascent fibers; s4, sucking monomer impurities from the nascent fibers through a monomer suction device, cooling and forming under a constant-temperature and constant-humidity side blowing condition, and bundling to form pre-network fibers; and S5, the pre-interlaced fibers are drafted and subjected to heat setting through two stages of grading drafting rollers, then pass through a main network to form a node yarn speed, and then are wound through a guide disc to form a spinning cake. The process is efficient, simple and convenient, the chinlon FDY fiber has medium-high strength and low boiling shrinkage in mechanical performance, meanwhile, the dyeing performance is good, evenness is uniform, the broken filament rate is low, and the anti-fuzzing and anti-pilling performance grade of the woven fabric is improved.

Description

Technical Field

[0001] The invention relates to a highly efficient preparation method of anti-pilling medium-high-strength and low-boiling shrinkage nylon FDY fiber. Background Art

[0002] Nylon, also known as nylon, is the first high-performance fiber to be industrialized and is currently the second largest synthetic fiber category. It is favored by high-end sports, outdoor, home textile and other clothing and bedding fabrics due to its excellent wear resistance, high strength, elasticity, comfort, high and low temperature resistance. However, with the continuous upgrading of consumption, the various indicators of clothing and home textile fabrics are also being upgraded and replaced, and the homogeneous competition of terminal brands is becoming more and more fierce. Major brands are seeking more excellent nylon fiber materials to meet the high-end needs of finished fabrics, so as to stand out and lead the market.

[0003] Among them, the demand for nylon fabrics to improve their anti-pilling level and better dimensional stability is imminent. The traditional method is to achieve high strength through high-viscosity raw materials with higher molecular weight combined with drafting. However, the fluidity of high-viscosity raw materials is poor, which limits the specifications and types of fibers used in fabrics. In addition, high-strengthening technical means are bound to lead to a significant reduction in dyeing performance and the lack of hand comfort. It is difficult to ensure uniform dyeing of fabrics while achieving physical properties. Therefore, the development of a material that can meet the physical property upgrade of high-grade nylon fabrics while retaining the original advantages has become a technical problem that needs to be solved in the industry. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides an efficient preparation method of nylon FDY fiber with medium-high strength and low boiling shrinkage and resistance to pilling. The process is efficient and simple, and can make the nylon FDY fiber have medium-high strength and low boiling shrinkage in mechanical properties while having good dyeing performance, uniform yarn evenness, and low lint rate, which is convenient for industrial promotion, so that the anti-pilling performance level of the woven fabric is improved, which meets the overall grade improvement application requirements of high-end clothing, home textiles, etc.

[0005] To achieve the above object, the technical solution adopted by the present invention is an efficient preparation method of anti-pilling medium-high strength low boiling shrinkage nylon FDY fiber, comprising the following steps:

[0006] S1. Preparation, extraction and drying of in-situ polymerized nylon slices;

[0007] S2, the in-situ polymerized nylon slices obtained in step S1 are melted by a screw extruder to obtain a melt, and the process is protected by nitrogen;

[0008] S3, the melt is evenly distributed to the spinning box through the distribution pipe, and is sprayed out by the high-pressure filter assembly to form primary fibers;

[0009] S4, the nascent fibers are subjected to monomer extraction device to extract monomer impurities, cooled and formed under constant temperature and humidity side blowing conditions, and oiled, and then bundled into pre-network fibers;

[0010] S5, the pre-network fiber is stretched and heat-set by two-stage graded drafting rollers, then passes through the main network to form a node wire speed, and then is wound on a guide plate to form a wire cake, so as to obtain a pilling-resistant medium-high-strength and low-shrinkage nylon FDY fiber.

[0011] In one embodiment of the present invention, the in-situ polymerized nylon slice is a nylon 6 slice obtained by in-situ polymerization of a reactive amine heat stabilizer, a reactive acid molecular weight concentration control agent and caprolactam; the added mass fraction of the reactive amine stabilizer is 0.1-0.3%, and the added mass fraction of the reactive acid molecular weight concentration control agent is 0.3-0.5%.

[0012] In one embodiment of the present invention, after the in-situ polymerized nylon 6 chips are extracted, the mass fraction of the monomer content is ≤0.2%; after the in-situ polymerized nylon 6 chips are dried, the moisture content is 200-500 ppm and the relative viscosity is 2.43-2.52.

[0013] In one embodiment of the present invention, in step S2, the screw extruder adopts 5-7 zone heating, the heating temperature is 258-275°C; the head pressure of the screw extruder is 110-145kg / cm 2 .

[0014] In one embodiment of the present invention, in step S3, the heating temperature of the spinning beam is 259-276°C.

[0015] In one embodiment of the present invention, in step S3, the high-pressure filter assembly includes metal coarse sand, metal fine sand and a metal sand filter screen, the metal coarse sand particle size is 60-80 mesh, the metal fine sand particle size is 100-120 mesh, and the ratio of metal coarse sand to metal fine sand is 1:1-1:2; the metal sand filter screen is 7 layers of 10μ-7 layers of 20μ.

[0016] In one embodiment of the present invention, in step S3, the primary fibers are formed by spraying out from a spinneret, and a filter screen is also provided on the spinneret, which has 5 layers of 10μ to 6 layers of 20μ.

[0017] In one embodiment of the present invention, the spinneret holes are elliptical or circular in shape, arranged in a diamond or circular shape, and have an aspect ratio of 2:1-4:1.

[0018] In one embodiment of the present invention, in step S4, the suction pressure of the monomer suction device is 0.7-2.0 kg / cm 2The cooling temperature of the side blowing air is 16-18°C, the humidity is 90-95%, the wind speed is 0.4-0.6m / s, the oiling amount is 1.3-2.3%, and the pre-network pressure is 0.2-0.4kg / cm 2 .

[0019] In one embodiment of the present invention, in step S5, the two-stage stretching rollers are composed of three groups of rollers, the temperature of the first group of rollers is room temperature-100°C, the temperature of the second group of rollers is 160-185°C, the temperature of the third group of rollers is 165-190°C, the stretching multiple of the first stage of the two-stage stretching is 1.2-1.5, and the stretching multiple of the second stage is 1.05-1.15.

[0020] In one embodiment of the present invention, in step S5, the main network pressure is 3-5 kg / cm 2 ; The speed of the guide disk is 4600-4700m / min; the winding speed is 4450-4650m / min; the silk cake winding surface pressure is 180-220N.

[0021] This technical solution has the following beneficial effects:

[0022] 1. In the process of in-situ polymerization of nylon 6, reactive amine heat stabilizers and reactive acid molecular weight centralized control agents are added to participate in the ring-opening polymerization of caprolactam. The prepared chips have a relatively low viscosity, which ensures the fluidity of the fiber spinning process, so that the fiber specifications are not restricted. At the same time, the heat resistance of the chips is good and the molecular weight distribution is more concentrated, which provides a guarantee for the subsequent hot drawing to present medium-high reinforcement and excellent quality.

[0023] 2. Nitrogen protection is used in the spinning process, the screw head pressure is high, the high-pressure component contains two layers of filter screens for filtration and monomer suction, which further effectively avoids and filters out the small molecules generated during the melt flow process, making the quality of the primary fiber more uniform;

[0024] 3. Through only two stages of drafting, the temperature of the hot roller is gradually increased, the drafting multiple is added in stages, and the reasonable optimization and matching of the front and back processes are systematically utilized to make the fiber orientation more uniform, the breaking strength presents medium-to-high reinforcement, the dimensional stability of low boiling shrinkage, and at the same time, it has the characteristics of uniform yarn, excellent dyeing performance, and low hair rate.

[0025] 4. The pilling-resistant medium-high-strength and low-boiling-shrinkage nylon FDY fiber prepared by the method of the present invention innovates the traditional method and only requires relatively low-viscosity slices to control the thermal stability and molecular weight concentration of the slices, further avoids or reduces the generation of small molecules during the spinning process, and only requires two-stage drafting process conditions. The efficient and fast one-step method enables the nylon 6 fiber to achieve medium-high-strength and low-boiling-shrinkage characteristics, and has the advantages of excellent dyeing, uniform yarn dryness, and low fuzz rate, so that the woven fabric has improved anti-pilling grade and more stable size, meets the high-end upgrading needs of terminal fabrics, and lays a good foundation for the differentiated development of nylon fibers. The entire preparation method is simple, novel and reasonable, low cost, high product quality, and broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of a process flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0027] Below is a combination of the embodiments and the attached Figure 1 The present invention is further described.

[0028] Conventional nylon FDY fiber has a breaking strength of 4.8-5.5 g / d, a breaking elongation of 38-46%, a boiling water shrinkage of 10-12%, and a pilling rating of 2.5-3.0 for the woven fabric; while the pilling-resistant medium-high-strength and low-boiling shrinkage nylon FDY fiber prepared by the method has a breaking strength of 6.2-7.5 g / d, a breaking elongation of 32-43%, a boiling water shrinkage of 8-9.7%, and a pilling rating of 3.5-4.5 for the woven fabric. The production process of the method is as follows: Figure 1 As shown: the reactive amine heat stabilizer, the reactive acid molecular weight concentration control agent and the caprolactam are in-situ polymerized to obtain nylon 6 chips with good thermal stability and concentrated molecular weight distribution. After extraction and drying, the chips are melted by a screw extruder to obtain a melt. The melt is evenly distributed to the spinning box through a distribution pipe, and is sprayed out by a high-pressure filter component to form nascent fibers. The nascent fibers are subjected to monomer suction device to suck monomer impurities, and are cooled and formed under constant temperature and humidity side blowing conditions, and are oiled, and are then bundled into pre-network fibers by a pre-network; then two-stage drafting roller drafting and shaping are performed, and then the node silk speed is formed through the main network, and then the silk cake is formed by winding after passing through the guide plate, that is, the anti-pilling medium-high strength and low boiling shrinkage nylon FDY fiber is formed.

[0029] Example 1

[0030] An efficient preparation method of anti-pilling medium-high-strength low-shrinkage nylon FDY fiber. The method comprises the following steps:

[0031] 1) Preparation, extraction and drying of in-situ polymerized nylon chips;

[0032] The in-situ polymerized nylon slice is a nylon 6 slice having good thermal stability and concentrated molecular weight distribution obtained by in-situ polymerization of a reactive amine heat stabilizer, a reactive acid molecular weight concentration control agent and caprolactam;

[0033] The added mass fraction of the reactive amine stabilizer in the in-situ polymerized nylon 6 slice is 0.1%, and the added mass fraction of the reactive acid molecular weight concentration control agent is 0.3%;

[0034] After the in-situ polymerized nylon 6 slices are extracted, the monomer content is controlled to be 0.2% by mass;

[0035] After the in-situ polymerized nylon 6 slices are dried, the moisture content is controlled to 200 ppm and the relative viscosity is controlled to 2.43;

[0036] 2) The in-situ polymerized nylon 6 slices in step 1 are melted through a silo and a screw extruder to obtain a melt, and the process is protected by nitrogen;

[0037] The screw extruder adopts 5-zone heating, and the heating temperature is 258°C;

[0038] The screw extruder head pressure is 110kg / cm2;

[0039] 3) The melt is evenly distributed to the spinning manifold through a distribution pipe and sprayed out by a high-pressure filter assembly to form nascent fibers;

[0040] The heating temperature of the spinning manifold is 259°C;

[0041] The particle size of the metal coarse sand in the high-pressure filter assembly is 60-80 mesh, the particle size of the metal fine sand is 100-120 mesh, and the ratio of the metal coarse sand to the metal fine sand is 1:1;

[0042] The metal sand filter in the assembly is 7 layers of 10μ, and the filter on the spinneret is 5 layers of 10μ;

[0043] The spinneret holes of the spinneret are elliptical in shape, arranged in a diamond shape, and have an aspect ratio of 2:1.

[0044] 4) The nascent fibers are subjected to monomer extraction device to extract monomer impurities, cooled and formed by constant temperature and humidity side blowing conditions, oiled by a double-channel oil nozzle, and then bundled into pre-network fibers by pre-network;

[0045] The suction pressure of the monomer suction device is 0.7kg / cm2;

[0046] The cooling temperature of the side blowing air is 16°C, the humidity is 90%, the wind speed is 0.4m / s, the oiling amount is 1.3%, and the pre-network pressure is 0.2kg / cm2;

[0047] 5) The pre-network fiber is drawn and heat-set by two-stage graded drawing rollers, then passes through the main network to form a node wire speed, and then passes through a guide plate and is wound to form a wire cake, that is, a high-strength and low-shrinkage nylon FDY fiber with anti-pilling and high strength is formed;

[0048] The two-stage drafting rollers are composed of three groups of rollers, the temperature of the first group of rollers is room temperature, the temperature of the second group of rollers is 160°C, and the temperature of the third group of rollers is 165°C. The two-stage drafting is that the first stage drafting multiple is 1.2, and the second stage drafting multiple is 1.05;

[0049] The main network pressure is 3kg / cm2;

[0050] The speed of the guide plate is 4600m / min;

[0051] The winding speed is 4450m / min;

[0052] The winding surface pressure of the silk cake is 180N.

[0053] The pilling-resistant medium-high-strength and low-boiling shrinkage nylon FDY fiber prepared by the method has a breaking strength of 6.2 g / d, a breaking elongation of 43%, a boiling water shrinkage of 9.7%, a yarn uniformity of 0.7%, a dyeing grade of 5, a fuzz rate of 0%, and a pilling rating of 3.5 for the woven fabric.

[0054] Example 2

[0055] An efficient preparation method of anti-pilling medium-high-strength low-shrinkage nylon FDY fiber. The method comprises the following steps:

[0056] 1) Preparation, extraction and drying of in-situ polymerized nylon chips;

[0057] The in-situ polymerized nylon slice is a nylon 6 slice having good thermal stability and concentrated molecular weight distribution obtained by in-situ polymerization of a reactive amine heat stabilizer, a reactive acid molecular weight concentration control agent and caprolactam;

[0058] The added mass fraction of the reactive amine stabilizer in the in-situ polymerized nylon 6 slice is 0.3%, and the added mass fraction of the reactive acid molecular weight concentration control agent is 0.5%;

[0059] After the in-situ polymerized nylon 6 slices are extracted, the mass fraction of the monomer content is controlled to be 0.05%;

[0060] After the in-situ polymerized nylon 6 slices are dried, the moisture content is controlled to 500ppm and the relative viscosity is controlled to 2.52;

[0061] 2) The in-situ polymerized nylon 6 slices in step 1 are melted through a silo and a screw extruder to obtain a melt, and the process is protected by nitrogen;

[0062] The screw extruder adopts 7-zone heating, and the heating temperature is 275°C;

[0063] The screw extruder head pressure is 145kg / cm2;

[0064] 3) The melt is evenly distributed to the spinning manifold through a distribution pipe and sprayed out by a high-pressure filter assembly to form nascent fibers;

[0065] The heating temperature of the spinning manifold is 276°C;

[0066] The particle size of the metal coarse sand in the high-pressure filter assembly is 60-80 mesh, the particle size of the metal fine sand is 100-120 mesh, and the ratio of the metal coarse sand to the metal fine sand is 1:2;

[0067] The metal sand filter in the assembly is 7 layers of 20μ, and the filter on the spinneret is 6 layers of 20μ;

[0068] The spinneret holes of the spinneret are circular in shape, arranged in a circular shape, and have an aspect ratio of 4:1;

[0069] 4) The nascent fibers are subjected to monomer extraction device to extract monomer impurities, cooled and formed by constant temperature and humidity side blowing conditions, oiled by a double-channel oil nozzle, and then bundled into pre-network fibers by pre-network;

[0070] The suction pressure of the monomer suction device is 2.0 kg / cm2;

[0071] The cooling temperature of the side blowing air is 18°C, the humidity is 95%, the wind speed is 0.6m / s, the oiling amount is 2.3%, and the pre-network pressure is 0.4kg / cm2;

[0072] 5) The pre-network fiber is drawn and heat-set by two-stage graded drawing rollers, then passes through the main network to form a node wire speed, and then passes through a guide plate and is wound to form a wire cake, that is, a high-strength and low-shrinkage nylon FDY fiber with anti-pilling and high strength is formed;

[0073] The two-stage drafting rollers are composed of three groups of rollers, the temperature of the first group of rollers is 100°C, the temperature of the second group of rollers is 185°C, and the temperature of the third group of rollers is 190°C. The two-stage drafting is that the first stage drafting multiple is 1.5, and the second stage drafting multiple is 1.15;

[0074] The main network pressure is 5kg / cm2;

[0075] The speed of the guide plate is 4700m / min;

[0076] The winding speed is 4650m / min;

[0077] The winding surface pressure of the silk cake is 220N.

[0078] The pilling-resistant medium-high-strength and low-boiling shrinkage nylon FDY fiber prepared by the method has a breaking strength of 7.5 g / d, a breaking elongation of 32%, a boiling water shrinkage of 8%, a yarn uniformity of 0.9%, a dyeing grade of 4.5, a fuzz rate of 1%, and a pilling rating of 4.5 for the woven fabric.

[0079] Example 3

[0080] An efficient preparation method of anti-pilling medium-high-strength low-shrinkage nylon FDY fiber. The method comprises the following steps:

[0081] 1) Preparation, extraction and drying of in-situ polymerized nylon chips;

[0082] The in-situ polymerized nylon slice is a nylon 6 slice having good thermal stability and concentrated molecular weight distribution obtained by in-situ polymerization of a reactive amine heat stabilizer, a reactive acid molecular weight concentration control agent and caprolactam;

[0083] The added mass fraction of the reactive amine stabilizer in the in-situ polymerized nylon 6 slice is 0.2%, and the added mass fraction of the reactive acid molecular weight concentration control agent is 0.4%;

[0084] After the in-situ polymerized nylon 6 slices are extracted, the monomer content is controlled to be 0.1% by mass;

[0085] After the in-situ polymerized nylon 6 slices are dried, the moisture content is controlled to 350ppm and the relative viscosity is controlled to 2.48;

[0086] 2) The in-situ polymerized nylon 6 slices in step 1 are melted through a silo and a screw extruder to obtain a melt, and the process is protected by nitrogen;

[0087] The screw extruder adopts 6-zone heating, and the heating temperature is 265°C;

[0088] The screw extruder head pressure is 125kg / cm2;

[0089] 3) The melt is evenly distributed to the spinning manifold through a distribution pipe and sprayed out by a high-pressure filter assembly to form nascent fibers;

[0090] The heating temperature of the spinning manifold is 267°C;

[0091] The particle size of the metal coarse sand in the high-pressure filter assembly is 60-80 mesh, the particle size of the metal fine sand is 100-120 mesh, and the ratio of the metal coarse sand to the metal fine sand is 1:1.5;

[0092] The metal sand filter in the assembly is 7 layers of 15μ, and the filter on the spinneret is 6 layers of 15μ;

[0093] The spinneret holes of the spinneret are elliptical in shape, arranged in a circle, and have an aspect ratio of 3:1;

[0094] 4) The nascent fibers are subjected to monomer extraction device to extract monomer impurities, cooled and formed by constant temperature and humidity side blowing conditions, oiled by a double-channel oil nozzle, and then bundled into pre-network fibers by pre-network;

[0095] The suction pressure of the monomer suction device is 1.4 kg / cm2;

[0096] The cooling temperature of the side blowing air is 17°C, the humidity is 93%, the wind speed is 0.5m / s, the oiling amount is 1.8%, and the pre-network pressure is 0.3kg / cm2;

[0097] 5) The pre-network fiber is drawn and heat-set by two-stage graded drawing rollers, then passes through the main network to form a node wire speed, and then passes through a guide plate and is wound to form a wire cake, that is, a high-strength and low-shrinkage nylon FDY fiber with anti-pilling and high strength is formed;

[0098] The two-stage drafting rollers are composed of three groups of rollers, the temperature of the first group of rollers is 50°C, the temperature of the second group of rollers is 172°C, and the temperature of the third group of rollers is 177°C. The two-stage drafting is that the first stage drafting multiple is 1.35, and the second stage drafting multiple is 1.1;

[0099] The main network pressure is 4kg / cm2;

[0100] The speed of the guide plate is 4650m / min;

[0101] The winding speed is 4550m / min;

[0102] The winding surface pressure of the silk cake is 200N.

[0103] The pilling-resistant medium-high-strength and low-boiling shrinkage nylon FDY fiber prepared by the method has a breaking strength of 7.0 g / d, a breaking elongation of 37%, a boiling water shrinkage of 8.5%, a yarn uniformity of 0.8%, a dyeing grade of 5, a hair rate of 0.5%, and a pilling rating of 4 for the woven fabric.

[0104] The above specific embodiments are only used to illustrate the present invention rather than to limit the present invention. Any changes and substitutions made to the present invention without creative work within the scope of protection of the present invention and the claims shall fall within the scope of protection of the patent of the present invention.

Claims

1. An efficient preparation method of high-strength and low-shrinkage nylon FDY fiber with anti-pilling properties, characterized in that: The steps include: S1. Preparation, extraction and drying of in-situ polymerized nylon slices; S2, the in-situ polymerized nylon slices obtained in step S1 are melted by a screw extruder to obtain a melt, and the process is protected by nitrogen; S3, the melt is evenly distributed to the spinning box through the distribution pipe, and is sprayed out by the high-pressure filter assembly to form primary fibers; S4, the nascent fibers are subjected to monomer extraction device to extract monomer impurities, cooled and formed under constant temperature and humidity side blowing conditions, and oiled, and then bundled into pre-network fibers; S5, the pre-network fiber is stretched and heat-set by two-stage graded drafting rollers, then passes through the main network to form a node wire speed, and then is wound on a guide plate to form a wire cake, so as to obtain a pilling-resistant medium-high-strength and low-shrinkage nylon FDY fiber.

2. The preparation method according to claim 1, characterized in that: The in-situ polymerized nylon slice is a nylon 6 slice obtained by in-situ polymerization of a reactive amine heat stabilizer, a reactive acid molecular weight concentration control agent and caprolactam; the added mass fraction of the reactive amine stabilizer is 0.1-0.3%, and the added mass fraction of the reactive acid molecular weight concentration control agent is 0.3-0.5%.

3. The preparation method according to claim 2, characterized in that: After the in-situ polymerized nylon 6 slices are extracted, the mass fraction of the monomer content is ≤0.2%; after the in-situ polymerized nylon 6 slices are dried, the moisture content is 200-500ppm and the relative viscosity is 2.43-2.

52.

4. The preparation method according to claim 1, characterized in that: In step S2, the screw extruder adopts 5-7 zone heating, the heating temperature is 258-275°C; the head pressure of the screw extruder is 110-145kg / cm 2 .

5. The preparation method according to claim 1, characterized in that: In step S3, the heating temperature of the spinning manifold is 259-276°C.

6. The preparation method according to claim 1, characterized in that: In step S3, the high-pressure filter assembly includes metal coarse sand, metal fine sand and a metal sand filter. The metal coarse sand particle size is 60-80 mesh, the metal fine sand particle size is 100-120 mesh, and the ratio of metal coarse sand to metal fine sand is 1:1-1:2; the metal sand filter is 7 layers of 10μ-7 layers of 20μ.

7. The preparation method according to claim 6, characterized in that: In step S3, primary fibers are formed by spraying out from a spinneret, and a filter screen is also provided on the spinneret, which has 5 layers of 10μ to 6 layers of 20μ.

8. The preparation method according to claim 1, characterized in that: In step S4, the suction pressure of the monomer suction device is 0.7-2.0kg / cm2; the cooling temperature of the side blowing is 16-18°C, the humidity is 90-95%, the wind speed is 0.4-0.6m / s, the oiling amount is 1.3-2.3%, and the pre-network pressure is 0.2-0.4kg / cm 2 .

9. The preparation method according to any one of claims 1 to 8, characterized in that: In step S5, the two-stage drafting rollers are composed of three groups of rollers, the temperature of the first group of rollers is room temperature-100°C, the temperature of the second group of rollers is 160-185°C, and the temperature of the third group of rollers is 165-190°C. The first stretching multiple of the two-stage drafting is 1.2-1.5, and the second stretching multiple is 1.05-1.

15.

10. The preparation method according to claim 9, characterized in that: In step S5, the main network pressure is 3-5 kg / cm 2 ; The speed of the guide disk is 4600-4700m / min; the winding speed is 4450-4650m / min; the silk cake winding surface pressure is 180-220N.

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