Preparation method of regenerated chinlon 6 fiber

Abstract

The invention discloses a preparation method of regenerated chinlon 6 fibers, and belongs to semi-chemical regenerated chinlon 6 fibers. The method comprises the following steps: firstly, recovering and sorting chinlon 6 waste silk, hot-pressing into cakes, freezing and crushing, washing and drying to obtain chinlon 6 waste silk particles; secondly, carrying out chain extension modification on the chinlon 6 waste silk particles by utilizing a CBC chain extender to obtain a chain extension modified regenerated chinlon 6 melt; on the basis, a compound mixture heat stabilizer of Cli-330 and JHX-100 is used for carrying out heat-resistant modification on the chain extension modified regenerated chinlon 6 melt, and the regenerated chinlon 6 spinning master batch is obtained through the steps of extrusion of a double-screw pelletizer, water-cooling solidification, grain-sized dicing, drying and the like; and finally, blending the regenerated chinlon 6 spinning master batch and the native chinlon particles in proportion, and carrying out melt spinning to obtain the regenerated chinlon 6 fiber.

Description

Technical Field

[0001] The present invention belongs to the technical field of differential fiber preparation, and particularly relates to a method for preparing regenerated polyamide 6 fiber. Background Art

[0002] Polyamide 6, scientifically named polyamide fiber 6, also called nylon 6, is the second largest chemical fiber variety after polyester in terms of output. Polyamide 6 fiber has excellent wear resistance, high strength, good resilience, soft touch, skin-friendly property and good hygroscopicity, and is widely used in medium and high-grade indoor seamless clothing such as yoga clothes, underwear and fitness clothes, as well as clothing materials for down jackets, mountaineering clothes, and outdoor sports shoes and clothes. However, as a non-degradable synthetic fiber, various waste polyamide products have caused great pressure on the environment. Among them, waste silk, waste materials and defective products generated during the production process of polyamide 6 are one of the main sources of waste polyamide 6, accounting for 2% - 5% of the polyamide 6 output.

[0003] However, most polyamide chemical fiber spinning enterprises do not effectively recycle such a large amount of polyamide 6 waste silk, but dispose of it by burning or selling at a low price, which not only causes waste of enterprise resources and increases production costs, but also causes a large amount of polyamide waste pollution. In recent years, with the enhancement of people's environmental protection awareness and the maturity of regenerated chemical fiber production technology, regenerated polyamide 6 products have begun to enter the market and are accepted by people. Currently, major international well-known sports shoes and clothing brands, such as Nike, Adidas, Uniqlo, etc., have announced that their products will gradually use regenerated polyamide 6 to replace virgin polyamide. Driven by the raw material use requirements of downstream shoe and clothing enterprises and the economic benefits of the enterprises themselves, major polyamide chemical fiber enterprises around the world have begun to develop regenerated polyamide technology.

[0004] Currently, regenerated polyamide technology is mainly divided into chemical method and physical method. The chemical method refers to a recovery method in which specific chemical solvents are used to depolymerize polyamide waste silk and waste materials to form caprolactam monomers with relatively low molecular weights, and then re-polymerize and purify them into polyamide spinning chips. The process is complex, the cost is high, and the chemical solvents are polluting. The physical method refers to a method in which the recycled polyamide waste is crushed, degreased and decontaminated, and then spun by secondary melt granulation. The process is relatively simple and the cost is low. However, after the polyamide waste is subjected to secondary melt granulation, thermal degradation occurs and the molecular weight decreases, resulting in poor spinnability of regenerated polyamide 6 particles and low quality of regenerated polyamide 6 fiber products. Therefore, developing a production technology for high-quality regenerated polyamide 6 fiber with simple process and low cost has become an urgent problem to be solved in the field of regenerated polyamide 6 fiber. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract, and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0007] Therefore, an object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing regenerated polyamide 6 fiber.

[0008] To solve the above technical problems, the present invention provides the following technical solution: A method for preparing regenerated polyamide 6 fiber, characterized in that it includes:

[0009] Recycling and sorting polyamide 6 waste filaments, hot pressing into cakes, cryogenic grinding, washing, and drying;

[0010] The dried polyamide 6 waste filament particles are subjected to chain extension modification to obtain a modified regenerated polyamide 6 melt;

[0011] The modified regenerated polyamide 6 melt is subjected to heat resistance modification, pelletized and extruded, water-cooled and solidified, cut into pellets, and dried to obtain a regenerated polyamide 6 spinning masterbatch;

[0012] The regenerated polyamide 6 masterbatch is blended with virgin polyamide 6 particles and melt-spun to obtain regenerated polyamide 6 fiber.

[0013] As a preferred embodiment of the preparation method of the present invention, wherein: the temperature of the hot pressing is 150 - 170 °C, and the pressure is 2 - 3 MPa.

[0014] As a preferred embodiment of the preparation method of the present invention, wherein: for the cryogenic grinding, the cryogenic treatment is liquid nitrogen freezing, and the polyamide 6 waste filament particles are ground into particles with a particle size of 1 - 3 mm.

[0015] As a preferred embodiment of the preparation method of the present invention, wherein: the polyamide 6 waste filament particles are washed 2 - 3 times and then vacuum dried at a drying temperature of 100 - 110 °C for 8 - 10 hours.

[0016] As a preferred embodiment of the preparation method of the present invention, wherein: for the chain extension modification of the dried polyamide 6 waste filament particles, the chain extender is 1,1'-carbonyl-bis-caprolactam (CBC), and the mass of the chain extender is 0.25 - 1% of the mass of the waste polyamide 6 particles.

[0017] As a preferred embodiment of the preparation method of the present invention, wherein: the temperature of the chain extension modification is 265 - 275 °C, and the reaction time of the chain extension modification is 30 - 40 min.

[0018] As a preferred embodiment of the preparation method of the present invention, wherein: the modified recycled polyamide 6 melt is subjected to heat resistance modification, and a heat stabilizer is added for heat resistance modification. The heat stabilizer is a compound mixture of a polyether ester polymer Cli-330 and an amide polymer JHX-100.

[0019] As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of the polyether ester polymer Cli-330 to the amide polymer JHX-100 is 4-6:6-4, and the addition amount of the heat stabilizer is 1-1.5% of the mass of the waste polyamide 6 particles.

[0020] As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of the recycled polyamide 6 spinning masterbatch to the virgin polyamide 6 particles is 7-2:3-8.

[0021] Another object of the present invention is to overcome the deficiencies in the prior art and provide a recycled polyamide 6 fiber.

[0022] Advantages of the present invention:

[0023] (1) The present invention introduces a CBC chain extender to perform chain extension modification on waste silk particles, improving the melt rheological properties and fiber strength; in addition, the use of a compound heat stabilizer of Cli-330 and JHX-100 further enhances the heat resistance of the material, thereby significantly improving the properties of the recycled polyamide 6 fiber.

[0024] (2) The present invention combines physical pretreatment and chemical modification through a semi-chemical method, avoiding the high energy consumption and equipment requirements of the full chemical method and breaking through the limitations of the insufficient performance of the recycled materials by the pure physical method. Description of the drawings

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. Among them:

[0026] Figure 1 It is the molecular weight distribution curve of the recycled polyamide 6 particles prepared in Example 1.

[0027] Figure 2 It is the molecular weight distribution curve of the recycled polyamide 6 particles prepared in Example 1, Example 4, Example 5, Comparative Example 1, and Comparative Example 2.

[0028] Figure 3Comparison of the breaking strength of the regenerated polyamide 6 fibers prepared in Example 1, Example 4, Example 5, Comparative Example 1, and Comparative Example 2.

[0029] Figure 4 Molecular weight distribution curves of the regenerated polyamide 6 particles prepared in Example 6, Example 7, Comparative Example 3, and Comparative Example 4.

[0030] Figure 5 Comparison of the breaking strength of the regenerated polyamide 6 fibers prepared in Example 1, Example 6, Example 7, Comparative Example 3, and Comparative Example 4. Detailed Description of the Invention

[0031] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following detailed description of the specific embodiments of the present invention will be given in conjunction with the embodiments of the specification.

[0032] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0033] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0034] Unless otherwise specified, the materials used in the present invention are all commonly available on the market.

[0035] Example 1

[0036] This example provides a method for preparing regenerated polyamide 6 fibers, which includes the following steps:

[0037] (1) Recycling and sorting polyamide 6 waste filaments, feeding them into a hot pressing box for hot pressing treatment. The temperature inside the box is 150 °C, and a pressure of 2 MPa is applied to the polyamide 6 waste filaments inside the box through a hydraulic system to obtain polyamide 6 waste filament cakes.

[0038] (2) After the polyamide 6 waste filament cakes are naturally cooled, they are fed into a liquid nitrogen freezing crusher and crushed into polyamide 6 waste filament particles with a particle size of 1 mm.

[0039] (3) Washing the polyamide 6 waste filament particles with a detergent twice and then feeding them into a vacuum dryer for drying. The drying temperature is 110 °C, and the drying time is 8 hours.

[0040] (4) The dried small particles of waste polyamide 6 filaments are fed into a melting and kneading reactor, and 1,1'-carbonyl-bis-caprolactam (CBC) chain extender is added for chain extension modification. The proportion of the chain extender is 0.4% of the mass of the waste polyamide 6 particles. The temperature inside the melting and kneading reactor is 265 °C, and the chain extension modification reaction time is 40 minutes to obtain a chain extension modified recycled polyamide 6 melt.

[0041] (5) The chain extension modified recycled polyamide 6 melt is fed into a twin-screw extruder, and a heat stabilizer is added for heat resistance modification. The heat stabilizer is a compound mixture of a polyether ester polymer Cli-330 and an amide polymer JHX-100. The compounding ratio of Cli-330 to JHX-100 is 4:6, and the addition amount of the heat stabilizer is 1.2% of the mass of the waste polyamide 6 particles.

[0042] (6) The heat resistance modified polyamide 6 melt is extruded by a twin-screw granulator, water-cooled and solidified, pelletized, and dried to obtain recycled polyamide 6 spinning masterbatch.

[0043] (7) The dried recycled polyamide 6 masterbatch and virgin polyamide 6 particles are blended at a mass ratio of 7:3 and fed into a melt spinning machine for melt spinning to obtain recycled polyamide 6 fibers.

[0044] Example 2

[0045] This example provides a method for preparing recycled polyamide 6 fibers, including the following steps:

[0046] (1) The waste polyamide 6 filaments are recycled and sorted, and then fed into a hot pressing box for hot pressing treatment. The temperature inside the box is 160 °C, and a pressure of 2.5 MPa is applied to the waste polyamide 6 filaments inside the box through a hydraulic system to obtain waste polyamide 6 cakes.

[0047] (2) After the waste polyamide 6 cakes are naturally cooled, they are fed into a liquid nitrogen freezing crusher and crushed into waste polyamide 6 particles with a particle size of 2 mm.

[0048] (3) The waste polyamide 6 particles are washed twice with a detergent and then fed into a vacuum dryer for drying. The drying temperature is 105 °C, and the drying time is 9 hours.

[0049] (4) The dried small particles of waste polyamide 6 filaments are fed into a melting and kneading reactor, and 1,1'-carbonyl-bis-caprolactam (CBC) chain extender is added for chain extension modification. The proportion of the chain extender is 0.5% of the mass of the waste polyamide 6 particles. The temperature inside the melting and kneading reactor is 270 °C, and the chain extension modification reaction time is 35 minutes to obtain a chain extension modified recycled polyamide 6 melt.

[0050] (5) Feed the chain-extended and modified recycled polyamide 6 melt into a twin-screw extruder, and add a heat stabilizer for heat resistance modification. The heat stabilizer is a compound mixture of a polyether ester high polymer Cli-330 and an amide high polymer JHX-100. The compounding ratio of Cli-330 to JHX-100 is 5:5, and the addition amount of the heat stabilizer is 1.3% of the mass of the waste polyamide 6 particles.

[0051] (6) The heat-resistant modified polyamide 6 melt is extruded by a twin-screw granulator, solidified by water cooling, pelletized, and dried to obtain recycled polyamide 6 spinning masterbatch.

[0052] (7) Blend the dried recycled polyamide 6 masterbatch and virgin polyamide 6 particles in a mass ratio of 6:4, and feed them into a melt spinning machine for melt spinning to obtain recycled polyamide 6 fibers.

[0053] Example 3

[0054] This example provides a method for preparing recycled polyamide 6 fibers, including the following steps:

[0055] (1) Recycle and sort the polyamide 6 waste silk, and feed it into a hot pressing box for hot pressing treatment. The temperature in the box is 170 °C, and a pressure of 3 MPa is applied to the polyamide 6 waste silk in the box through a hydraulic system to obtain a polyamide 6 waste silk cake.

[0056] (2) After the polyamide 6 waste silk cake is naturally cooled, feed it into a liquid nitrogen freezing crusher and crush it into polyamide 6 waste silk particles with a particle size of 3 mm.

[0057] (3) Wash the polyamide 6 waste silk particles with a detergent 3 times, and then feed them into a vacuum dryer for drying. The drying temperature is 100 °C, and the drying time is 10 hours.

[0058] (4) Feed the dried small polyamide 6 waste silk particles into a melt mixing reactor, and add 1,1'-carbonyl-bis-caprolactam (CBC) chain extender for chain extension modification. The proportion of the chain extender is 0.8% of the mass of the waste polyamide 6 particles. The temperature in the melt mixing reactor is 275 °C, and the chain extension modification reaction time is 30 minutes to obtain a chain-extended and modified recycled polyamide 6 melt.

[0059] (5) Feed the chain-extended and modified recycled polyamide 6 melt into a twin-screw extruder, and add a heat stabilizer for heat resistance modification. The heat stabilizer is a compound mixture of a polyether ester high polymer Cli-330 and an amide high polymer JHX-100. The compounding ratio of Cli-330 to JHX-100 is 6:4, and the addition amount of the heat stabilizer is 1.4% of the mass of the waste polyamide 6 particles.

[0060] (6) The heat-resistant modified polyamide 6 melt is extruded by a twin-screw granulator, solidified by water cooling, pelletized, and dried to obtain recycled polyamide 6 spinning masterbatch.

[0061] (7) Mix the dried regenerated nylon 6 masterbatch and virgin nylon 6 particles in a mass ratio of 5:5, and send them into a melt spinning machine for melt spinning to obtain regenerated nylon 6 fibers.

[0062] Example 4

[0063] The difference between this example and Example 1 is that the proportion of the chain extender in step (4) is replaced with 1% of the mass of the waste nylon 6 particles, and the remaining steps are the same as those in Example 1. It is found that the molecular weight of the regenerated nylon 6 particles prepared in Example 4 is almost the same as that of the regenerated nylon 6 particles prepared in Example 1, and the breaking strength of the regenerated nylon 6 fibers prepared in Example 4 is also not much different from that of the regenerated nylon 6 fibers prepared in Example 1.

[0064] Example 5

[0065] The difference between this example and Example 1 is that the proportion of the chain extender in step (4) is replaced with 0.25% of the mass of the waste nylon 6 particles, and the remaining steps are the same as those in Example 1. It is found that the molecular weight of the regenerated nylon 6 particles prepared in Example 5 is almost the same as that of the regenerated nylon 6 particles prepared in Example 1, and the breaking strength of the regenerated nylon 6 fibers prepared in Example 5 is also not much different from that of the regenerated nylon 6 fibers prepared in Example 1.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that the proportion of the chain extender in step (4) is replaced with 1.5% of the mass of the waste nylon 6 particles, and the remaining steps are the same as those in Example 1. It is found that the molecular weight of the regenerated nylon 6 particles prepared in Comparative Example 1 is less than that of the regenerated nylon 6 particles prepared in Example 1, and the breaking strength of the regenerated nylon 6 fibers prepared in Comparative Example 1 is less than that of the regenerated nylon 6 fibers prepared in Example 1.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that the proportion of the chain extender in step (4) is replaced with 0.1% of the mass of the waste nylon 6 particles, and the remaining steps are the same as those in Example 1. It is found that the molecular weight of the regenerated nylon 6 particles prepared in Comparative Example 2 is less than that of the regenerated nylon 6 particles prepared in Example 1, and the breaking strength of the regenerated nylon 6 fibers prepared in Comparative Example 2 is less than that of the regenerated nylon 6 fibers prepared in Example 1.

[0070] Example 6

[0071] The difference between this example and Example 1 is that the addition amount of the heat stabilizer in step (5) is replaced with 1.5% of the mass of the waste polyamide 6 particles, and the remaining steps are the same as those in Example 1. It is found that the molecular weight of the recycled polyamide 6 particles prepared in Example 6 is almost the same as that of the recycled polyamide 6 particles prepared in Example 1, and the breaking strength of the recycled polyamide 6 fibers prepared in Example 6 is also not much different from that of the recycled polyamide 6 fibers prepared in Example 1.

[0072] Example 7

[0073] The difference between this example and Example 1 is that the addition amount of the heat stabilizer in step (5) is replaced with 1% of the mass of the waste polyamide 6 particles, and the remaining steps are the same as those in Example 1. It is found that the molecular weight of the recycled polyamide 6 particles prepared in Example 7 is almost the same as that of the recycled polyamide 6 particles prepared in Example 1, and the breaking strength of the recycled polyamide 6 fibers prepared in Example 7 is also not much different from that of the recycled polyamide 6 fibers prepared in Example 1.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is that the addition amount of the heat stabilizer in step (5) is replaced with 1.8% of the mass of the waste polyamide 6 particles, and the remaining steps are the same as those in Example 1. It is found that the molecular weight of the recycled polyamide 6 particles prepared in Comparative Example 3 is less than that of the recycled polyamide 6 particles prepared in Example 1, and the breaking strength of the recycled polyamide 6 fibers prepared in Comparative Example 3 is less than that of the recycled polyamide 6 fibers prepared in Example 1.

[0076] Comparative Example 4

[0077] The difference between this comparative example and Example 1 is that the addition amount of the heat stabilizer in step (5) is replaced with 0.8% of the mass of the waste polyamide 6 particles, and the remaining steps are the same as those in Example 1. It is found that the molecular weight of the recycled polyamide 6 particles prepared in Comparative Example 4 is less than that of the recycled polyamide 6 particles prepared in Example 1, and the breaking strength of the recycled polyamide 6 fibers prepared in Comparative Example 4 is less than that of the recycled polyamide 6 fibers prepared in Example 1.

[0078] It should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for preparing regenerated polyamide 6 fiber, characterized in that: including recovering, sorting, hot pressing into cakes, cryogenic grinding, washing, and drying the waste nylon 6 filaments; performing chain extension modification on the dried waste nylon 6 filament particles to obtain a modified recycled nylon 6 melt; performing heat resistance modification on the modified recycled nylon 6 melt, granulating and extruding, water-cooling and solidifying, pelletizing, and drying to obtain recycled nylon 6 spinning masterbatch; mixing the recycled nylon 6 masterbatch with virgin nylon 6 particles and melt spinning to obtain recycled nylon 6 fibers.

2. The preparation method according to claim 1, characterized in that: The temperature of the hot pressing is 150-170°C, and the pressure is 2-3 MPa.

3. The preparation method according to claim 1, characterized in that: For the cryogenic grinding, the cryogenic treatment is liquid nitrogen freezing, and the nylon 6 waste filament particles are ground into particles with a particle size of 1-3 mm.

4. The preparation method according to claim 3, characterized in that: The nylon 6 waste filament particles are washed 2-3 times and then vacuum dried at a drying temperature of 100-110°C for 8-10 hours.

5. The preparation method according to claim 1, characterized in that: For the chain extension modification of the dried nylon 6 waste filament particles, the chain extender is 1,1'-carbonyl-bis-caprolactam (CBC), and the mass of the chain extender is 0.25-1% of the mass of the waste nylon 6 particles.

6. The preparation method according to claim 1, characterized in that: The temperature of the chain extension modification is 265-275°C, and the reaction time of the chain extension modification is 30-40 min.

7. The preparation method according to claim 1, wherein: For the heat resistance modification of the modified recycled nylon 6 melt, a heat stabilizer is added for heat resistance modification, and the heat stabilizer is a compound mixture of a polyether ester polymer Cli-330 and an amide polymer JHX-100.

8. The preparation method according to claim 7, wherein: The mass ratio of the polyether ester polymer Cli-330 to the amide polymer JHX-100 is 4-6:6-4, and the addition amount of the heat stabilizer is 1-1.5% of the mass of the waste nylon 6 particles.

9. The preparation method according to claim 1, wherein: The mass ratio of the recycled nylon 6 spinning masterbatch to the virgin nylon 6 particles is 7-2:3-8.

10. Recycled nylon 6 fibers prepared by the preparation method according to any one of claims 1-9.

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