Humidity response chinlon and preparation method thereof

Abstract

The invention relates to the field of textiles, in particular to environment-friendly humidity response chinlon which can be stably and efficiently produced and is high in strength and simple in process and a preparation method of the environment-friendly humidity response chinlon. PVA slices are extruded through a screw to prepare cross-linked modified PVA, a melt of the cross-linked modified PVA and modified chinlon are blended to serve as a core layer, conventional chinlon slices are selected as a main raw material of a skin layer, and humidity response chinlon is prepared through a skin-core spinning method; wherein the skin layer blending material comprises 98-99% of chinlon, and the core blending material comprises 40-75% of modified chinlon and 25-50% of cross-linked modified PVA. According to the preparation method of the humidity response chinlon, the chinlon prepared through the method has the good moisture absorption and sweat releasing effects after being woven into fabric, the intelligent humidity adjusting function is achieved, and the method is suitable for the fields of sportswear, medical textiles and the like; and the moisture absorption rate is high, so that the fiber and the fabric thereof also have a good antistatic effect.

Description

Technical Field

[0001] This invention relates to the textile field, and more particularly to a humidity-responsive nylon and its preparation method. Background Technology

[0002] Today, with the improvement of consumption levels both domestically and internationally, the public's requirements for clothing performance are also constantly increasing. Previously, only fashion and warmth were required; now, comfort and health are also essential. Among these, moisture-wicking and quick-drying functionality is a pressing need for summer clothing such as sportswear and T-shirts. Moisture-responsive fibers possess moisture memory function, capable of changing shape between wet and dry states, thus giving clothing fabrics special functional characteristics. Furthermore, a high moisture absorption rate can endow the fibers and their fabrics with good antistatic properties.

[0003] Patent CN112575404A discloses a method for preparing highly sensitive humidity-responsive fibers. First, conductive nanomaterials are uniformly dispersed in a hydrophilic polymer to form a conductive nanomaterial / hydrophilic polymer solution. Then, wet spinning is performed to obtain gel fibers. These fibers are then contacted with a deliquescent salt solution for solvent replacement and drying to obtain the highly sensitive humidity-responsive fibers. This method uses wet spinning, resulting in fibers with low strength. It also requires two solvent treatments, making the preparation process complex, costly, and difficult to mass-produce. Furthermore, the use of solvents is environmentally unfriendly. A similar patent, CN113106747A, discloses a method for preparing a humidity-responsive bilayer composite nanofiber membrane. This method also requires solvent dissolution, which is environmentally unfriendly. The process involves dissolution, electrospinning, and vapor deposition trimming, making the preparation process complex, costly, and difficult to mass-produce.

[0004] Patent CN112853549A discloses a humidity-responsive graphene smart fiber. This fiber possesses moisture-absorbing and conductive properties by laminating a layer of graphene material onto a highly absorbent core layer. The inner fiber layer is prepared through melt spinning, while the outer layer is created using an unknown implanter to embed dispersed graphene into the inner fiber layer via a double-sided hot air implantation method. However, this method produces fibers with several drawbacks. 1. Since the graphene is blown onto the inner layer material by hot air, the graphene will be evenly distributed on the inner layer and cannot form a continuous phase. This will lead to a surge in fiber unevenness and graphene will be considered an impurity, which will cause a serious reduction in fiber strength. 2. During the melt spinning process, fiber stability is crucial. Hot air can cause the fibers to float, easily leading to fiber breakage, affecting spinning stability, making high-speed spinning impossible, and limiting production output. 3. The method mentions that fiber preparation involves melt spinning, hot air pressing, cleaning, and drying, which are numerous and complex processes. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a humidity-responsive nylon with good stability, high strength, simple and environmentally friendly process and a method for its preparation.

[0006] This invention is implemented as follows: This invention first provides a method for preparing humidity-responsive nylon. PVA chips are extruded by screw extrusion to prepare cross-linked modified PVA. The melt is blended with modified nylon to form the core layer, while the sheath layer uses conventional nylon chips as the main raw material. Humidity-responsive nylon is obtained by core-sheath spinning. The sheath blend includes 98-99% nylon, and the core blend includes 40-75% modified nylon and 25-50% cross-linked modified PVA. All percentages represent the mass percentage of their respective blends.

[0007] Furthermore, the PVA is cross-linked by screw extrusion to obtain cross-linked modified PVA melt. This melt is melt-blended with modified nylon melt and then conveyed to the core layer. The cross-linked modified PVA is made from raw materials comprising the following mass percentages: 20-45% PVA, 2-3% cross-linking agent, 0-5% plasticizer, and 0-1% dehydrating agent. The above percentages represent the mass percentages of the core blend.

[0008] Specifically, a reactive screw extruder with a vacuum pump connected to the screw is used in the preparation of cross-linked PVA. During the high-temperature extrusion process in the screw extruder, the modified raw material undergoes varying degrees of decomposition, precipitation, and gasification, forming a large amount of low-molecular-weight gaseous mixture. This mixture is then removed from the molten material and discharged through a vacuum pipe.

[0009] Furthermore, the crosslinked modified PVA is made from the following raw materials in the indicated weight percentages: 20-30% PVA, 2% plasticizer, 2-2.5% diacid crosslinking agent, and 0.4-0.8% dehydrating agent.

[0010] Preferably, the crosslinked modified PVA is made from the following raw materials in the indicated weight percentages: 30% PVA, 2% plasticizer, 2.5% diacid crosslinking agent, and 0.6% dehydrating agent.

[0011] in: Dicarboxylic acid crosslinking agents (such as succinic acid and adipic acid) are used to obtain crosslinked modified PVA. Their main characteristics are that the molecular chain has a lot of hydrophilic hydroxyl groups (-OH), which have high hygroscopicity. Due to the existence of the crosslinked structure, it can absorb a large amount of water and swell, thereby deforming the entire fiber and giving it the function of absorbing and wicking away moisture, but it will not degrade and has good reversible moisture absorption and desiccation.

[0012] Plasticizers such as zinc oxide or sorbitol are used to increase the melt flowability of PVA, lower its processing temperature, and prevent high-temperature decomposition. The dehydrating agent, polycarbodiimide, is used to remove the moisture produced by the cross-linking reaction, allowing the cross-linking reaction to proceed in the forward direction and preventing polymer degradation.

[0013] Furthermore, the PVA is partially alcoholyzed, with a degree of alcoholysis of 88%.

[0014] Furthermore, the modified nylon 6 has a melting point of 195-210℃. The modified PA6 is prepared from copolymers of PA6 with PA66, PA10, PA11, PA12, etc. (such as Evonik PA612, DuPont PA610, BASF PA666), with a melting point of 195-210℃ and a relative viscosity of 2.3-2.7. This is to lower the spinning temperature of the melt, thereby conforming to the processing temperature window of PVA and preventing high-temperature decomposition of PVA.

[0015] Furthermore, the leather blend consists of the following components: 98-99% nylon and 1-2% carbon nanotubes, with the total mass percentage of the above components being 100%.

[0016] Furthermore, the core blend consists of the following components: 40-75% modified nylon, 25-50% crosslinked modified PVA, and 1-2% maleic anhydride-grafted POE, with the total mass percentage of the above components being 100%.

[0017] The solubilizer-maleic anhydride grafted POE is used to increase the interfacial compatibility between PA and PVA, improve the uniformity of the fiber, and thus ensure the excellent overall performance of the fiber.

[0018] Furthermore, the mass ratio of the skin blend to the core blend is 6-8:2-4, preferably 6:4.

[0019] The present invention also provides a humidity-responsive nylon prepared by the aforementioned preparation method.

[0020] The present invention has the following advantages: This invention provides a method for preparing humidity-responsive nylon. PVA is cross-linked by screw extrusion to obtain cross-linked modified PVA melt. This melt is blended with modified nylon melt as the core layer, while the sheath layer uses conventional nylon chips as the main raw material. Humidity-responsive nylon is obtained by one-step sheath-core spinning. The entire preparation process does not require the production of chips and is simple and convenient.

[0021] The nylon fabric prepared by this method exhibits excellent moisture absorption and wicking properties, achieving intelligent humidity regulation, and is suitable for sportswear, medical textiles, and other fields. Its moisture absorption deformation principle is as follows: In high humidity environments, moisture permeates through the fiber sheath and is absorbed by the modified PVA in the core layer. The PVA swells after absorbing water, and because the PVA is located in the core layer and is surrounded by nylon material, its swelling is constrained by the sheath. Therefore, the transverse swelling deformation is transformed into axial shrinkage deformation, resulting in shorter fibers. This enlarges the pores formed by the interlacing of fibers in the fabric, improving breathability, enhancing moisture absorption and quick-drying performance, and improving clothing comfort. Furthermore, due to its high moisture absorption, the fabric woven from this fiber also possesses excellent antistatic properties. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a flowchart illustrating the execution process of the method of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Unless otherwise specified in the embodiments, conditions are performed according to conventional conditions or conditions recommended by the manufacturer. Materials whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0025] A method for preparing humidity-responsive nylon specifically includes the following steps: (1) Nylon chips and polyvinyl alcohol chips were selected as raw materials, carbon nanotubes were selected as pore-forming agents for the outer layer, and maleic anhydride-grafted POE was selected as compatibilizer for the core layer.

[0026] (2) Humidity-responsive nylon was prepared using the core-sheath spinning method. The sheath material consisted of 98-99% nylon 6 chips and 1-2% carbon nanotubes. The carbon nanotubes provided capillary effect and increased the active water absorption performance of the fiber. The core material consisted of 40-75% modified nylon 6 chips (Evonik PA612), 25-50% modified PVA, and 1-2% maleic anhydride-grafted POE (KOAS, brand: W1A). The specific formulation is shown in Table 1 (the performance comparison in Table 1 is based on the same process conditions).

[0027] The modified PVA is cross-linked modified PVA, and the cross-linking agent is a diacid, such as succinic acid. The main characteristic of cross-linked modified PVA is that its molecular chain has a large number of hydrophilic hydroxyl groups (-OH), resulting in high hygroscopicity. Due to the presence of the cross-linked structure, it can absorb a large amount of water and swell, thereby deforming the entire fiber and giving it moisture-wicking function, but it will not degrade and has good reversible moisture absorption and desiccation. The raw materials of cross-linked modified PVA are fed into a screw extruder according to the following ratio (20-30% PVA, 2% plasticizer, 2-2.5% diacid cross-linking agent, 0.4-0.8% dehydrating agent), and the cross-linked modified PVA melt is obtained after screw extrusion.

[0028] Maleic anhydride-grafted POE is used as a solubilizer. Its main function is to increase the compatibility between modified PVA and modified nylon, and to avoid phase separation that could lead to abnormal production and low fiber strength.

[0029] (3) The raw materials of the skin layer and the core layer are mixed in proportion by two masterbatch machines, and then melted and mixed by two different screw extruders. The mixture is then transported to the same spinning box through the melt pipeline, and then transported to the same component by two sets of metering pumps. In the same component, the melt of the core layer and the skin layer flows through the corresponding distribution plate and merges at the spinneret to form a skin-core structure. The nascent fibers forming the skin-core structure are then ejected from the spinneret holes.

[0030] The ratio of the sheath to the core is (6-8):(2-4), ensuring that the sheath accounts for a larger proportion than the core, thereby ensuring that the fiber strength is not too low and does not meet the usage requirements.

[0031] The core layer component pressure is designed to be around 170-180 bar, and the sheath component pressure is designed to be around 160-170 bar, ensuring that the core layer component pressure is 5-11% higher than the sheath component pressure. The higher core layer pressure is to ensure that the core melt can be stably filled, forming a better core-sheath structure. In addition, the spinneret orifices can be designed with irregular cross-sections, such as three-lobed, four-lobed, five-lobed, and six-lobed shapes, which can increase the fiber cross-sectional area, thereby improving the fiber's moisture absorption effect. Moreover, this type of cross-section has a better capillary effect, which can better improve the fiber's moisture absorption and perspiration wicking effect. Furthermore, the fiber core-sheath structure can be designed eccentrically, which can accelerate the fiber's water absorption deformation response.

[0032] The temperatures of zones 1 to 5 of the screw are as follows: skin layer: 250℃-255℃; core layer: 190℃, 200℃, 205℃, 206℃, 206℃. The lower core layer temperature is to ensure that the modified PVA does not degrade while still meeting processing requirements. Vacuum pumps are connected to the core layer screw exhaust port and the melt pipe after the screw, with a minimum vacuum of -0.09MPa, to further remove moisture generated during the crosslinking reaction, ensuring the reaction proceeds forward and preventing polymer degradation caused by moisture.

[0033] (4) The melt forming the core structure is ejected from the spinneret and passes through the single-unit suction device, side blowing, oil nozzle oiling, guide hook, channel, pre-networker, cold roller, hot roller, main networker, guide disc, guide hook, and finally wound into shape by the winding head.

[0034] The process parameters are as follows: side blowing air 0.45-0.65m / min, 18℃; cold roller speed 3400m / min, hot roller speed 4590m / min, drawing ratio 1.35, setting temperature 142℃, and spinning speed 4500m / min.

[0035] As shown in Table 1, the proportion of cross-linked modified PVA has the greatest impact on the wet length of the fiber. A higher proportion results in higher hygroscopicity and better antistatic properties, but also a decrease in fiber breaking strength and a decline in production stability. Formula 4 is the preferred option, with a lower core layer proportion (lower cost), higher fiber strength, and more stable production. Formula 6 has a lower moisture regain, minimal fiber size change, and poor hygroscopicity. Formula 7, without carbon nanotubes, has poor hygroscopic and antistatic properties, and minimal fiber size change. Formula 8, without maleic anhydride-grafted POE, has lower breaking strength, poor hygroscopic and antistatic properties, and lower production stability. Formula 9, without plasticizers, has unsatisfactory performance in all aspects. Formula 10, without cross-linking agents, cannot achieve hygroscopic and desiccant cycles because the PVA is not cross-linked; excessive moisture absorption can lead to PVA degradation and a significant decrease in fiber strength. Formula 11, without dehydrating agents, has unsatisfactory performance in all aspects.

[0036]

[0037] Note: Moisture regain test conditions: 30℃, 80% humidity.

[0038] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing humidity-responsive nylon, characterized in that: PVA chips are extruded by screw extrusion to prepare cross-linked modified PVA. The melt is blended with modified nylon to form the core layer, while the skin layer uses conventional nylon chips as the main raw material. Humidity-responsive nylon is obtained by core-sheath spinning. The skin layer blend consists of 98-99% nylon, and the core blend consists of 40-75% modified nylon and 25-50% cross-linked modified PVA. All percentages represent the mass percentage of each blend.

2. The method for preparing humidity-responsive nylon according to claim 1, characterized in that: The PVA is cross-linked by screw extrusion to obtain cross-linked modified PVA melt. This melt is melt-blended with modified nylon melt and then conveyed to the core layer. The cross-linked modified PVA is made from raw materials comprising the following mass percentages: 20-45% PVA, 2-3% cross-linking agent, 0-5% plasticizer, and 0-1% dehydrating agent. The above percentages represent the mass percentages of the core blend.

3. The method for preparing humidity-responsive nylon according to claim 2, characterized in that: The crosslinking agent is a diacid.

4. The method for preparing humidity-responsive nylon according to claim 1, characterized in that: The modified nylon has a melting point of 195-210℃ and a relative viscosity of 2.3-2.

7.

5. The method for preparing humidity-responsive nylon according to claim 1, characterized in that: The leather blend consists of the following components: 98-99% nylon and 1-2% carbon nanotubes, with the total mass percentage of the above components being 100%.

6. The method for preparing humidity-responsive nylon according to claim 1, characterized in that: The core blend consists of the following components: 40-75% modified nylon, 25-55% crosslinked modified PVA, and 1-2% maleic anhydride-grafted POE, with the total mass percentage being 100%.

7. The method for preparing humidity-responsive nylon according to claim 1, characterized in that: The mass ratio of the skin blend to the core blend is 6-8:2-4.

8. Humidity-responsive nylon prepared by any one of claims 1-6.

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