Preparation method of elastic nylon 6, and manufacturing method and equipment of parallel composite elastic fiber

Abstract

The present invention relates to the technical field of elastic fiber preparation, and provides a method for preparing elastic nylon 6, a method for manufacturing a parallel composite elastic fiber, and an apparatus, comprising the following steps: based on the mass of the solvent, adding polyethylene-octene copolymer POE, maleic anhydride MAH, and an initiator to obtain a grafted POE; adding hexamethylenediamine, the grafted POE and hexamethylenediamine undergo an amidation reaction to obtain an amino-modified POE; caprolactam undergoes a ring-opening reaction to generate aminocaproic acid; aminocaproic acid undergoes a polymerization reaction to generate nylon 6; adding amino-modified POE and nylon 6 to undergo an amidation reaction to obtain elastic nylon 6. By this, the present invention introduces POE into the nylon 6 molecular chain through grafting reaction and amidation reaction, improves elasticity, and forms an elastic nylon 6 containing a flexible segment, and its heat shrinkage performance is significantly different from that of nylon 6. Elastic nylon 6 is obtained using low-cost nylon 6, which significantly reduces the cost of elastic components.

Description

Technical Field

[0001] The present invention belongs to the technical field of elastic fiber preparation, and in particular relates to a method for preparing elastic nylon 6, and a method and equipment for manufacturing parallel composite elastic fibers. Background Art

[0002] Parallel composite fibers are single fibers constructed by juxtaposing two different polymers. Heat treatment induces asymmetric thermal shrinkage between the two components, creating a stress differential within the fiber and ultimately achieving a spontaneous helical curl. This structure imparts excellent elastic recovery, softness, and a three-dimensional bulk, making it widely used in elastic yarns for clothing and functional fabrics.

[0003] In the manufacture of elastic parallel composite fibers, two polymers with different thermal shrinkage properties are usually selected as parallel components. The difference in thermal shrinkage between the two components is used to generate sufficiently large internal stress to drive curling, thereby achieving high elasticity of the fiber.

[0004] Existing parallel components are usually nylon 6 and nylon 66 or nylon 6 and nylon elastomer (TPAE). Because the cost of raw materials such as nylon 66 and nylon elastomer is much higher than that of nylon 6, the final composite elastic fiber product is expensive, which limits market promotion and application.

[0005] In summary, the existing technology has obvious inconveniences and defects in actual use, so it is necessary to improve it. Summary of the Invention

[0006] In view of the above-mentioned defects, the present invention mainly provides a method for preparing elastic nylon 6 to solve the technical problem of high cost of the elastic component of the existing composite elastic fiber.

[0007] In order to solve the above problems, the present invention provides a method for preparing elastic nylon 6, comprising the following steps:

[0008] S1, based on the mass of the solvent, add to the solvent: 30% by mass of polyethylene-octene copolymer POE, 5% to 20% by mass of maleic anhydride MAH, and 0.1% to 1% by mass of initiator;

[0009] At an initiation temperature of 60°C to 120°C, a free radical grafting reaction is initiated between maleic anhydride MAH and the main chain of polyethylene-octene copolymer POE to obtain grafted POE;

[0010] S2, adding 5% to 10% hexamethylenediamine by mass; at an amidation temperature of 80°C to 140°C, the grafted POE and hexamethylenediamine undergo an amidation reaction to obtain amino-modified POE;

[0011] S3, caprolactam undergoes a ring-opening reaction to produce aminocaproic acid; then, the aminocaproic acid undergoes a polymerization reaction to produce nylon 6; the polymerization reaction temperature is 250°C;

[0012] S4, adding amino-modified POE to undergo amidation reaction with nylon 6 to obtain elastic nylon 6; the amount of the amino-modified POE added is 4% to 8% of the mass of the caprolactam.

[0013] According to the method for preparing elastic nylon 6 of the present invention, the solvent in step S1 is toluene, and the initiator is dicumyl peroxide DCP.

[0014] According to the method for preparing elastic nylon 6 of the present invention, the amount of initiator used in step S1 is 0.5%, the initiation temperature is 90° C., and the amount of maleic anhydride used is 12%.

[0015] According to the method for preparing elastic nylon 6 of the present invention, the amidation temperature in step S2 is 110° C., and the amount of hexamethylenediamine added is 7%.

[0016] According to the method for preparing elastic nylon 6 of the present invention, the amount of amino-modified POE added in step S4 is 6% of the mass of caprolactam.

[0017] According to the method for preparing elastic nylon 6 of the present invention, the amidation reaction in step S4 includes reacting the terminal amino group of the amine-modified POE with the carboxyl group of nylon 6 and / or reacting the carboxyl group of the amine-modified POE with the amino group of nylon 6.

[0018] A method for manufacturing parallel composite elastic fibers comprises the following steps:

[0019] Z1, nylon 6 and elastic nylon 6 obtained by the elastic nylon 6 preparation method are melted and extruded to form filaments; the spinning temperature is 240°C to 280°C;

[0020] Z2, preparing parallel composite filaments from the two strands of yarn spun in step Z1;

[0021] Z3, sequentially subjecting the parallel composite filaments to cooling, stretching, heat setting and winding steps to obtain parallel composite elastic fibers; the stretching ratio is 1.5 to 5.0 times, and the heat setting temperature is 80° C. to 110° C.

[0022] According to the method for producing parallel composite elastic fibers of the present invention, the spinning temperature in step Z1 is 260°C.

[0023] According to the method for manufacturing parallel composite elastic fibers of the present invention, the stretching ratio in the Z3 step is 3.0 times, and the heat setting temperature is 95°C.

[0024] An apparatus for performing the method for manufacturing parallel composite elastic fibers, comprising:

[0025] Two extruders, each connected to a melt pump; the two extruders are used for melt extrusion of elastic nylon 6 and nylon 6 into filaments respectively;

[0026] A parallel spinneret assembly is used to introduce the filaments delivered by the melt pumps of the two extruders and to make the two strands of filaments into parallel composite filaments;

[0027] A drafting roller group having a plurality of drafting rollers for stretching parallel composite filaments;

[0028] Heat finishing machine, used for heat setting treatment of parallel composite filaments to produce parallel composite elastic fibers;

[0029] The winding roller is used for winding and collecting the prepared parallel composite elastic fibers.

[0030] In summary, the present invention's method for preparing elastic nylon 6 introduces polyethylene-octene copolymer (POE) into the nylon 6 molecular chain through grafting and amidation reactions. This reduces the regularity and crystallinity of the nylon 6 molecules while enhancing their elasticity, resulting in an elastic nylon 6 containing flexible segments whose thermal shrinkage performance significantly differs from that of nylon 6. This method utilizes low-cost nylon 6 to produce elastic nylon 6, significantly reducing the cost of the elastic component. The present invention also provides a method and apparatus for producing parallel composite elastic fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the grafting reaction of the present invention;

[0032] Figure 2 This is a schematic diagram of the reaction principle for generating amino-modified POE of the present invention;

[0033] Figure 3 This is a schematic diagram of the reaction principle for producing elastic nylon 6 according to the present invention;

[0034] Figure 4 It is a schematic structural diagram of the parallel composite elastic fiber manufacturing equipment of the present invention;

[0035] In the figure: 1-extruder, 2-melt pump, 3-parallel spinneret assembly, 31-oiling roller; 4-heat finishing machine, 41-drawing roller, 42-winding roller. DETAILED DESCRIPTION

[0036] See also Figure 1 The present invention provides a method for preparing elastic nylon 6, comprising the following steps:

[0037] S1, based on the mass of the solvent, add to the solvent: 30% by mass of polyethylene-octene copolymer (abbreviated as POE in the figure), 5% to 20% by mass of maleic anhydride (abbreviated as MAH in the figure), and 0.1% to 1% by mass of an initiator;

[0038] At an initiation temperature of 60°C to 120°C, a free radical grafting reaction is initiated between maleic anhydride (MAH) and the main chain of polyethylene-octene copolymer (POE) to obtain grafted POE (abbreviated as POE-g-MAH in the figure);

[0039] The initiator generates free radicals in the solvent, which remove a hydrogen atom from the POE backbone to produce activated POE. The activated POE then undergoes a grafting reaction with maleic anhydride (MAH) to produce grafted POE (POE-g-MAH).

[0040] As an embodiment, the solvent in step S1 of the present invention is toluene, and the initiator is dicumyl peroxide (DCP);

[0041] Furthermore, the amount of initiator was 0.5%, the initiation temperature was 90 °C, and the amount of maleic anhydride was 12%;

[0042] S2, see Figure 2 , then add 5% to 10% hexamethylenediamine by mass; at an amidation temperature of 80°C to 140°C, the grafted POE (POE-g-MAH) and hexamethylenediamine undergo amidation reaction to obtain amino-modified POE (abbreviated as POE-g-NH2 in the figure);

[0043] Reactive amine functional groups were introduced into the POE chain segment through amidation reaction to obtain amine-modified POE (POE-g-NH2).

[0044] Preferably, the amidation temperature in step S2 of the present invention is 110° C., and the amount of hexamethylenediamine added is 7%;

[0045] S3, see Figure 3 , caprolactam undergoes a ring-opening reaction to generate aminocaproic acid; then, aminocaproic acid undergoes a polymerization reaction to generate nylon 6; the polymerization reaction temperature is 250°C;

[0046] S4, adding amino-modified POE (POE-g-NH2) to undergo amidation reaction with nylon 6 to produce elastic nylon 6;

[0047] The amount of amino-modified POE (POE-g-NH2) added is 4% to 8% of the mass of caprolactam, preferably 6%.

[0048] Optionally, the viscosity of the elastic nylon 6 is controlled to be 2.4±0.2‌.

[0049] As an embodiment, the amidation reaction in step S4 includes the reaction of the terminal amino group of the amine-modified POE (POE-g-NH2) with the carboxyl group of nylon 6 and / or the reaction of the carboxyl group of the amine-modified POE (POE-g-NH2) with the amino group of nylon 6.

[0050] This invention introduces polyethylene-octene copolymer (POE) into the nylon 6 molecular chain through grafting and amidation reactions. This reduces the regularity and crystallinity of the nylon 6 molecules while increasing their elasticity, resulting in an elastic nylon 6 containing flexible segments. Its thermal shrinkage performance is significantly different from that of nylon 6. This invention uses low-cost nylon 6 to produce elastic nylon 6, significantly reducing the cost of the elastic component.

[0051] The present invention also provides a method for manufacturing parallel composite elastic fibers, comprising the following steps:

[0052] Z1, nylon 6 and elastic nylon 6 obtained by the elastic nylon 6 preparation method are melted and extruded to form filaments; the spinning temperature is 240°C to 280°C;

[0053] Preferably, the spinning temperature in step Z1 is 260°C.

[0054] Z2, preparing parallel composite filaments from the two strands of yarn spun in step Z1;

[0055] Z3, sequentially cooling, stretching, heat-setting, and winding the parallel composite filaments to obtain parallel composite elastic fibers; the stretching ratio is 1.5 to 5.0 times, and the heat-setting temperature is 80° C. to 110° C.;

[0056] Preferably, the stretching ratio in the Z3 step is 3.0 times, and the heat setting temperature is 95°C.

[0057] Due to the significant difference in thermal shrinkage between nylon 6 and elastic nylon 6, a non-uniform internal stress field is generated within the fiber, inducing helical curling in the axial direction, resulting in a parallel composite elastic fiber with excellent elasticity and resilience. The elastic nylon 6 of the present invention is made from relatively low-cost nylon 6, significantly lower than existing elastomers such as nylon 66 and TPAE, reducing the raw material cost of the parallel composite fiber.

[0058] The present invention uses nylon 6, nylon 66, nylon elastomer 6920 and the elastic nylon 6 of the present invention to conduct shrinkage test. Referring to Table 1, the shrinkage of the present invention is the largest and has a significant difference with nylon 6, which fully meets the requirements of the elastic component of the parallel composite fiber.

[0059] Table 1: Boiling water shrinkage test

[0060] sample Boiling water shrinkage / % Nylon 6 5.3 Nylon 66 6.2 Nylon elastomer 6920 23.8 Elastic nylon 6 38.6

[0061] The present invention used the aforementioned method to prepare multiple elastic nylon 6 samples, and then used these samples to prepare parallel composite elastic fibers as sample examples. Furthermore, to facilitate comparison, the present invention also used nylon 6 and nylon 66 as raw materials, using the parallel composite elastic fiber manufacturing method to prepare samples as comparative examples. Each sample example and comparative example was tested for crimp number and elastic recovery.

[0062] Specific experimental parameters and test results are shown in Table 2. (Note: Table 2 lists only the modified parameters; identical components and steps can be found in the previous text and are not repeated here.) The test results show that the crimp number and elastic recovery rate of the parallel composite fibers prepared using the elastic nylon 6 and nylon 6 of the present invention are significantly improved. This demonstrates that the elastic nylon 6 of the present application significantly improves the performance of the parallel composite fibers while reducing raw material costs.

[0063] Table 2 Parameters and test results of various embodiments and comparative examples

[0064]

[0065] See also Figure 4 The present invention also provides an apparatus for executing the method for manufacturing the parallel composite elastic fiber, comprising:

[0066] Two extruders 1, each extruder 1 is connected to a melt pump 2; the two extruders 1 are used for melt extrusion of elastic nylon 6 and nylon 6 into filaments respectively;

[0067] The parallel spinneret assembly 3 is used to introduce the filaments delivered by the melt pumps 2 of the two extruders 1 and to make the two strands of filaments into parallel composite filaments;

[0068] A drafting roller group having a plurality of drafting rollers 41 for stretching the parallel composite filaments;

[0069] a heat finishing machine 4 for heat setting the parallel composite filaments to produce parallel composite elastic fibers;

[0070] A winding roller 42 is used for winding and collecting the prepared parallel composite elastic fibers;

[0071] As an embodiment, an oiling roller 31 is provided between the parallel spinning assembly 3 and the drafting roller group for applying oil to the parallel composite filaments to reduce friction between fibers and between fibers and equipment, thereby avoiding brittle fracture in subsequent processes.

[0072] In summary, the present invention provides a method for preparing elastic nylon 6. Polyethylene-octene copolymer (POE) is introduced into the nylon 6 molecular chain through a grafting reaction and an amidation reaction. This reduces the regularity and crystallinity of the nylon 6 molecules while increasing their elasticity. This results in an elastic nylon 6 containing flexible segments, whose thermal shrinkage performance is significantly different from that of nylon 6. This method uses low-cost nylon 6 to produce elastic nylon 6, significantly reducing the cost of the elastic component. The present invention also provides a method and equipment for producing parallel composite elastic fibers.

[0073] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing elastic nylon 6, characterized in that: The steps include: S1, based on the mass of the solvent, add to the solvent: 30% by mass of polyethylene-octene copolymer POE, 5% to 20% by mass of maleic anhydride MAH, and 0.1% to 1% by mass of initiator; At an initiation temperature of 60°C to 120°C, a free radical grafting reaction is initiated between maleic anhydride MAH and the main chain of polyethylene-octene copolymer POE to obtain grafted POE; S2, adding 5% to 10% hexamethylenediamine by mass; at an amidation temperature of 80°C to 140°C, the grafted POE and hexamethylenediamine undergo an amidation reaction to obtain amino-modified POE; S3, caprolactam undergoes a ring-opening reaction to produce aminocaproic acid; then, the aminocaproic acid undergoes a polymerization reaction to produce nylon 6; the polymerization reaction temperature is 250°C; S4, adding amino-modified POE to undergo amidation reaction with nylon 6 to obtain elastic nylon 6; the amount of the amino-modified POE added is 4% to 8% of the mass of the caprolactam.

2. The method for preparing elastic nylon 6 according to claim 1, wherein: The solvent in step S1 is toluene, and the initiator is dicumyl peroxide DCP.

3. The method for preparing elastic nylon 6 according to claim 1, wherein: In step S1, the amount of initiator used is 0.5%, the initiation temperature is 90° C., and the amount of maleic anhydride used is 12%.

4. The method for preparing elastic nylon 6 according to claim 1, wherein: The amidation temperature in step S2 is 110° C., and the amount of hexamethylenediamine added is 7%.

5. The method for preparing elastic nylon 6 according to claim 1, wherein: The amount of amino-modified POE added in step S4 is 6% of the mass of caprolactam.

6. The method for preparing elastic nylon 6 according to claim 1, wherein: The amidation reaction in step S4 includes the reaction of the terminal amino group of the amine-modified POE with the carboxyl group of nylon 6 and / or the reaction of the carboxyl group of the amine-modified POE with the amino group of nylon 6.

7. A method for producing parallel composite elastic fibers, characterized in that: The steps include: Z1, nylon 6 and elastic nylon 6 obtained by the method for preparing elastic nylon 6 according to any one of claims 1 to 6 are melt-spinned and extruded into filaments; the spinning temperature is 240° C. to 280° C.; Z2, preparing parallel composite filaments from the two strands of yarn spun in step Z1; Z3, sequentially subjecting the parallel composite filaments to cooling, stretching, heat setting and winding steps to obtain parallel composite elastic fibers; the stretching ratio is 1.5 to 5.0 times, and the heat setting temperature is 80° C. to 110° C.

8. The method for producing a parallel composite elastic fiber according to claim 7, wherein: The spinning temperature in the Z1 step is 260°C.

9. The method for producing a parallel composite elastic fiber according to claim 7, wherein: The stretching ratio in the Z3 step is 3.0 times, and the heat setting temperature is 95°C.

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