Special nylon fabric for high-wear-resistance and tear-resistance knapsack

Abstract

The invention belongs to the technical field of textile materials, and discloses a high-wear-resistance tear-resistant nylon fabric special for a backpack. The fabric is prepared by composite spinning of bio-based pentamethylene diamine derived polyamide resin and bacterial nano cellulose hydrophobically modified by a biological enzyme method, the bio-based pentamethylene diamine derived polyamide resin and the bacterial nano cellulose hydrophobically modified by the biological enzyme method are synergistically enhanced through a molecular-level hydrogen bond interpenetrating network structure, and tear strength and wear resistance are remarkably improved on the premise that gram weight and hardness are not increased. According to the invention, nanocellulose synthesized by microorganisms and bio-based polyamide are coupled on a molecular level to construct an interpenetrating network structure with efficient energy dissipation capability, and the nylon fabric special for the high-wear-resistance and tear-resistance knapsack, which is novel in structure, excellent in performance and environment-friendly, is provided; the comprehensive performance indexes meet the requirements of high-end outdoor knapsacks on high strength, high wear resistance, light weight, softness and sustainability of the high-performance sustainable fabric.

Description

Technical Field

[0001] This invention belongs to the field of textile materials technology and relates to a nylon fabric for backpacks with high abrasion resistance and tear resistance. Background Technology In the manufacturing of outdoor sports equipment and functional bags, nylon (polyamide) has long been widely used as a core fabric substrate due to its excellent mechanical properties, abrasion resistance, and processing adaptability. Traditional technical approaches typically improve the tear strength of nylon fibers by increasing their denier or twisting. Increasing the fineness of single filaments can improve the load-bearing capacity per unit cross-sectional area, while high twisting inhibits tear propagation by increasing the friction between fibers. Both of these measures enhance the integrity of the fabric structure at the macroscopic mechanical level.

[0003] However, increasing the denier of fibers directly leads to an increase in weight per unit area, while high-twist processes significantly reduce yarn softness, resulting in a stiff feel and poor drape in the final fabric, which in turn affects the ergonomic fit and carrying experience of the backpack. Such reinforcement methods sacrifice material flexibility and lightweight in exchange for increased strength, making it difficult to meet the market's simultaneous demand for high performance and high comfort.

[0004] Against this backdrop, the industry has attempted to introduce inorganic nanofillers (such as silica and carbon nanotubes) or synthetic polymer toughening agents to improve the mechanical properties of nylon. However, such methods often face secondary problems such as poor dispersion uniformity, weak interfacial compatibility, high processing energy consumption, or lack of biodegradability. These problems may not only damage the hand feel and dyeing performance of the fabric, but also contradict the current global trend of advocating green and low-carbon manufacturing. Summary of the Invention

[0005] To achieve the above-mentioned objectives, this invention provides a high-abrasion-resistant and tear-resistant nylon fabric for backpacks. The fabric is made by composite spinning of bio-based pentanediamine-derived polyamide resin and bacterial nanocellulose modified by bio-enzymatic method. The bacterial nanocellulose is uniformly dispersed in the polyamide matrix as a nano-reinforcing phase and achieves synergistic enhancement of mechanical properties through a molecular-level hydrogen bond interpenetrating network structure. Without increasing the basis weight per unit area or the fabric stiffness, the tear resistance and abrasion resistance of the fabric are significantly improved.

[0006] The preparation method of the high abrasion-resistant and tear-resistant backpack-specific nylon fabric of the present invention includes the following steps: First, high-purity bacterial nanocellulose hydrogel is obtained by microbial fermentation of Acetobacter xylinum under static culture conditions; second, the hydrogel is pretreated to remove residual culture medium components and its solid content is adjusted to 3%-5%; subsequently, using lipase or laccase as a biocatalyst, long-chain fatty acids or alkylphenol hydrophobic agents are covalently grafted onto the hydroxyl groups on the surface of bacterial nanocellulose in a reaction system with a pH of 5.0-6.5 and a temperature of 35-45℃ to achieve surface hydrophobic modification; the resulting hydrophobically modified bacterial nanocellulose is then frozen. After drying, a fluffy and porous nanocellulose powder is obtained. This powder is mixed with nylon 56 or nylon 510 chips obtained by condensation of bio-based pentanediamine and adipic acid or sebacic acid at a mass ratio of 1:99 to 5:95, and melt-blended in a twin-screw extruder at 240-270℃ to obtain a composite masterbatch. The composite masterbatch is dried and fed into a melt spinning assembly, where it is spun into multifilament under the conditions of spinning temperature of 250-280℃, side-blowing speed of 0.4m / -0.6m / s, and winding speed of 3500-4500m / min. The obtained multifilament is then twisted, warped, woven, and finished to finally produce the high abrasion-resistant and tear-resistant backpack-specific nylon fabric.

[0007] The bacterial nanocellulose has a diameter of 20-100 nm, a length of 500-2000 nm, a crystallinity greater than 85%, and a specific surface area of ​​80-150 m². 2 / g. The lipase used in the hydrophobic modification process is an immobilized lipase CAL-B derived from Candida spp., with a catalytic activity greater than 10000 U / g; the hydrophobic agent used is at least one of lauric acid, stearic acid, or nonylphenol, with a carbon chain length of C12-C18. After hydrophobic modification, the contact angle of bacterial nanocellulose increased from the original 20°-30° to 95°-110°, indicating that its surface has successfully changed from hydrophilic to hydrophobic, thus possessing good interfacial compatibility with the polyamide matrix.

[0008] The bio-based pentanediamine is obtained by decarboxylation of lysine catalyzed by decarboxylase, and its bio-based carbon content is greater than 95%. Nylon 56 is formed by the condensation polymerization of pentanediamine and adipic acid, with an intrinsic viscosity of 1.8-2.2 dL / g. Nylon 510 is formed by the condensation polymerization of pentanediamine and sebacic acid, with an intrinsic viscosity of 1.6-2.0 dL / g. In the composite masterbatch, the mass fraction of hydrophobically modified bacterial nanocellulose is 1%-5%, preferably 3%; it is uniformly dispersed in the polyamide matrix in a three-dimensional network, without obvious agglomeration, and the dispersion scale is less than 200 nm.

[0009] In the melt spinning process, the twin-screw extruder operates at a screw speed of 200-300 rpm with a length-to-diameter ratio of 40:1. The temperature zones are set as follows: feeding section 180-200℃, compression section 220-240℃, and metering section 250-270℃. The spinning assembly uses a perforated spinneret with 24-96 holes and a diameter of 0.25-0.35 mm. The resulting multifilament has a single filament fineness of 1.0-2.0 dtex, a breaking strength greater than 5.5 cN / dtex, and a breaking elongation of 25%-35%.

[0010] The weaving process employs a high-density twill or plain weave structure, with warp and weft densities of 180-220 ends / inch in the warp and 160-200 ends / inch in the weft. The finishing process includes heat setting and water-repellent finishing. The heat setting temperature is 180-200℃ for 60-90 seconds; the water-repellent finishing uses a fluorinated acrylate finishing agent, applied through a pad-drying-baking process, with a pad-residue rate of 70%-80%, and a baking temperature of 150-170℃ for 2-3 minutes.

[0011] In another preferred embodiment of the present invention, the hydrophobically modified bacterial nanocellulose and the nylon 56 matrix form a dual interfacial bond through amide bonds and hydrogen bonds. During the melt blending process, a small amount of unreacted hydroxyl groups remaining on the surface of the bacterial nanocellulose form intermolecular hydrogen bonds with the amide groups in the nylon 56 molecular chain; at the same time, the long-chain alkyl groups introduced by the hydrophobic modification interact with the polyamide backbone through van der Waals forces, further enhancing interfacial adhesion.

[0012] Because bacterial nanocellulose has a high aspect ratio and high crystallinity, it aligns along the fiber axis in the melt flow shear field, forming a rigid nanoframework that penetrates the polyamide matrix; while the polyamide molecular chains are entangled and permeate the gaps in this framework, forming a continuous flexible network. Together, they construct a molecular-level interpenetrating network structure that combines rigidity and flexibility.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. When the fabric is subjected to local tear stress, the energy at the crack tip is first absorbed by the rigid bacterial nanocellulose network and rapidly conducted along its high modulus path; at the same time, the flexible polyamide network dissipates some energy through molecular chain slippage, unentanglement and rearrangement; the two mechanisms work together to effectively inhibit crack propagation and significantly improve tear resistance.

[0014] The fabric described in this invention is made entirely from bio-based raw materials. Pentylenediamine is derived from renewable biomass, bacterial nanocellulose is synthesized through microbial fermentation, and the bio-based carbon content of nylon 56 or nylon 510 is greater than 60%. The overall biodegradability of the material is superior to that of traditional petroleum-based nylon 66, aligning with the concept of green and low-carbon manufacturing. Furthermore, since it does not rely on high-density fibers or high-twist yarn processes, this invention achieves high strength while maintaining excellent softness and drape, significantly improving the ergonomic fit and comfort when carrying a backpack.

[0015] This invention achieves intrinsic enhancement of mechanical properties by constructing a bacterial nanocellulose / bio-based polyamide interpenetrating network at the molecular scale, without sacrificing lightweight and flexibility. Compared with solutions that add inorganic nanofillers, this invention uses a fully bio-based organic nano-reinforcing phase, avoiding problems such as difficult dispersion, weak interfacial bonding, and environmental unfriendliness. Compared with solutions that physically blend unmodified cellulose, this invention uses precise hydrophobic modification via bio-enzyme method to ensure uniform dispersion and strong interfacial bonding of the nanophase in the hydrophobic polyamide matrix, thereby truly exerting its reinforcing and toughening effects. Detailed Implementation

[0016] This invention provides a method for preparing a high abrasion-resistant and tear-resistant nylon fabric for backpacks. The core of this method is to modify bacterial nanocellulose hydrophobically through a bio-enzymatic method and then composite it with a bio-based pentanediamine-derived polyamide resin to construct a molecular-level interpenetrating network structure. This method simultaneously improves the tear resistance and abrasion resistance of the fabric without increasing the basis weight or fabric stiffness.

[0017] The technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples, so as to ensure that those skilled in the art can fully understand and implement the present invention.

[0018] Example 1: 97% bio-based polyamide resin, 3% bacterial nanocellulose modified by bio-enzymatic method; Bio-based polyamide resin: Nylon 56, intrinsic viscosity 2.0 dL / g, bio-based carbon content 65%, formed by the condensation polymerization of bio-based pentanediamine and adipic acid; Bacterial nanocellulose: 60 nm in diameter, 1200 nm in length, 88% crystallinity, and 120 m² specific surface area. 2 / g, obtained by static fermentation of Acetobacter xylinum, with a solid content of 4% after alkali boiling and water washing; Hydrophobic modification: Lipase CAL-B catalysis, stearic acid as hydrophobic agent, pH 5.8, temperature 40℃, water contact angle increased to 102°; Preparation steps: S1: Bacterial nanocellulose pretreatment, static fermentation of Acetobacter xylinum to obtain hydrogel, alkaline boiling to remove residual culture medium, water washing for purification, and adjustment of solid content to 4%; S2: Hydrophobic modification: Add bacterial nanocellulose dispersion to reaction vessel, adjust pH to 5.8, heat to 40℃, add lipase CAL-B and stearic acid, react at constant temperature for 4 hours, filter and freeze dry to obtain hydrophobic modified bacterial nanocellulose powder. S3: Preparation of composite masterbatch: Nylon 56 chips and modified bacterial nanocellulose powder are mixed at a mass ratio of 97:3 and added to a twin-screw extruder with a screw length-to-diameter ratio of 40:1, a rotation speed of 250 rpm, a feeding section temperature of 190°C, a compression section temperature of 230°C, and a metering section temperature of 260°C. Composite masterbatch is obtained by melt blending. S4: Melt spinning. After the composite masterbatch is dried, it is fed into the spinning machine. The spinning temperature is 265℃. A 48-hole spinneret with a hole diameter of 0.30 mm is used. The side blowing speed is 0.5 m / s and the winding speed is 4000 m / min to produce a multifilament with a single filament fineness of 1.5 dtex. S5: Yarn preparation, multifilament twisted to 800T / m, warping tension controlled at 8% of the single filament breaking strength; S6: Weave, using a high-density twill weave, with a warp density of 200 threads / inch and a weft density of 180 threads / inch; S7: Post-treatment, heat setting at 190℃ for 75 seconds, fluorinated acrylate finishing agent impregnation-drying-baking, roll-off rate 75%, baking temperature 160℃, time 2.5 minutes.

[0019] Example 2: 99% bio-based polyamide resin, 1% modified bacterial nanocellulose, with the remaining components and parameters the same as in Example 1; Preparation steps: Same as in Example 1 (compound ratio adjusted).

[0020] Example 3: 95% bio-based polyamide resin, 5% modified bacterial nanocellulose, with the remaining components and parameters the same as in Example 1; Preparation steps: Same as in Example 1.

[0021] Example 4: The bio-based polyamide resin is nylon 510 with an intrinsic viscosity of 1.8 dL / g and a bio-based carbon content of 62%. The remaining components and parameters are the same as in Example 1. Preparation steps: Same as in Example 1 (resin type adjusted).

[0022] Example 5: The hydrophobic modifier is lauric acid, which increases the water contact angle to 98°. The other components and parameters are the same as in Example 1. Preparation steps: Same as in Example 1 (adjustment of hydrophobic agent).

[0023] Example 6: Melt spinning winding speed 3500m / min, single filament fineness 1.8dtex, other components and parameters are the same as in Example 1; Preparation steps: Same as in Example 1 (spinning parameters adjusted).

[0024] Example 7: The weaving adopts a plain weave with a warp density of 190 ends / inch and a weft density of 170 ends / inch. The remaining components and parameters are the same as in Example 1. Preparation steps: Same as in Example 1 (weaving process adjusted).

[0025] Example 8: Post-treatment heat setting temperature 180℃, time 90 seconds, other components and parameters are the same as in Example 1; Preparation steps: Same as in Example 1 (after adjusting the finishing parameters).

[0026] Comparative Example 1: Petroleum-based nylon 66 resin, without added bacterial nanocellulose; Preparation steps: conventional melt spinning (spinning temperature 275℃), twisting (1000T / m), weaving, and finishing.

[0027] Comparative Example 2: 97% Nylon 56 resin, 3% unhydrophobic modified bacterial nanocellulose, with the remaining processes the same as in Example 1; Preparation steps: Same as in Example 1 (without hydrophobic modification step).

[0028] Test method: Physicochemical and mechanical property tests: weight per unit area was measured using an electronic balance; fabric thickness was measured using a thickness gauge; tear strength was measured in the warp and weft directions using a tear strength tester according to GB / T3917.2 standard; abrasion resistance was measured using a Martindale abrasion tester according to GB / T21196.3 standard; bending stiffness was measured using a fabric stiffness tester according to GB / T18318.1 standard; and the water contact angle of bacterial nanocellulose was measured using a contact angle meter.

[0029] Comfort and environmental performance testing: Moisture regain was measured in a constant temperature and humidity chamber according to GB / T21655.1 standard; softness and drape were evaluated by sensory evaluation method; and bio-based carbon content was determined by elemental analysis method.

[0030] Stability testing: Accelerated aging test (70℃, 80% relative humidity, 1000 hours) to test the retention rate of mechanical properties.

[0031] The test data comparisons are shown in Table 1 and Table 2.

[0032] Table 1 Comparison of unit area weight, warp tear strength, and weft tear strength

[0033] Table 2 Comparison of Martindale abrasion resistance cycles, radial bending stiffness, moisture regain, and bio-based carbon content

[0034] Examples 1-8 are significantly superior to the comparative examples in terms of lightweight, high strength, high abrasion resistance, and softness. Comparative Example 1 shows that traditional petroleum-based fabrics have high basis weight, a stiff feel, and insufficient mechanical properties; Comparative Example 2 shows that due to the lack of modification of bacterial nanocellulose, the interfacial compatibility with the polyamide matrix is ​​poor, and the aggregation leads to performance degradation, confirming that bio-enzymatic modification + molecular-level interpenetrating network is the core of the product's high performance.

[0035] The addition of modified bacterial nanocellulose increased (Examples 2→1→3), resulting in a significant improvement in tear strength and abrasion resistance, while the softness decreased slightly but was still superior to traditional fabrics; Nylon 56 resin (Example 1) was slightly better than Nylon 510 (Example 4) in terms of mechanical properties; the type of hydrophobic agent, spinning speed, weaving structure and finishing parameters had a mild impact on performance, and all met the requirements of high-end backpack fabrics.

[0036] Example product unit area weight ≤158g / m² 2 It has a warp tear strength of ≥128N, a Martindale abrasion resistance of ≥53,000 cycles, and a bending stiffness of ≤34mN·m, balancing lightweight, high strength, and flexibility; a bio-based carbon content of ≥61%, making it environmentally friendly and in line with the trend of green manufacturing; and a manufacturing process compatible with existing textile production lines, making it easy to scale up industrially.

[0037] Compared to traditional petroleum-based nylon 66 fabric (Comparative Example 1), Example 1 shows a 22.7% increase in warp tear strength, a 38.1% increase in abrasion resistance, a 21.1% reduction in basis weight, and a 28.9% reduction in bending stiffness. Compared to unmodified composite fabric (Comparative Example 2), it shows a 37.8% increase in tear strength and a 52.6% increase in abrasion resistance, thus solving the industry problem of balancing high strength, lightweight, and softness in existing fabrics.

[0038] In summary, the fabric described in this invention achieves a balance between high performance and environmental friendliness through bio-based raw material composite and precise modification processes, making it suitable for high-end outdoor backpacks and other scenarios with stringent requirements for the comprehensive performance of materials.

[0039] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high abrasion-resistant and tear-resistant nylon fabric for backpacks, characterized in that, The fabric is made by composite spinning of bio-based pentanediamine-derived polyamide resin and bacterial nanocellulose modified by bio-enzymatic method.

2. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 1, characterized in that, The bacterial nanocellulose is uniformly dispersed in the polyamide matrix as a nano-reinforcing phase, and the two achieve synergistic enhancement of mechanical properties through a molecular-level hydrogen-bonded interpenetrating network structure.

3. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 1, characterized in that, The hydrophobic modification involves covalently grafting long-chain fatty acids or alkylphenol hydrophobic agents with carbon chain lengths of C12-C18 onto the hydroxyl groups on the surface of bacterial nanocellulose via lipase or laccase catalysis, thereby increasing the water contact angle from the original 20°-30° to 95°-110°.

4. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 1, characterized in that, The polyamide resin is nylon 56 or nylon 510, which is formed by the condensation polymerization of bio-based pentanediamine with adipic acid or sebacic acid, respectively, and has an intrinsic viscosity of 1.8-2.2 dL / g or 1.6-2.0 dL / g, respectively.

5. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 1, characterized in that, The hydrophobically modified bacterial nanocellulose has a mass fraction of 1%-5% in the composite system.

6. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 1, characterized in that, The fabric has a thickness of 0.25-0.35mm, a warp tear strength greater than 120N, a weft tear strength greater than 100N, a Martindale abrasion resistance greater than 50,000 cycles, and a bending stiffness of less than 35mN·m in the warp and less than 30mN·m in the weft.

7. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 1, characterized in that, The bacterial nanocellulose was prepared by fermentation of Acetobacter xylinum under static culture conditions, and the solid content was adjusted to 3%-5% after purification by alkali boiling and water washing.

8. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 3, characterized in that, The hydrophobic modification was carried out at a pH of 5.0-6.5 and a temperature of 35-45℃. The lipase used was an immobilized lipase CAL-B derived from Candida spp. with a catalytic activity greater than 10000 U / g. The hydrophobic agent was at least one of lauric acid, stearic acid, or nonylphenol.

9. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 2, characterized in that, The hydrophobically modified bacterial nanocellulose and the polyamide matrix are bonded together through a dual interface of amide bonds and hydrogen bonds, and are oriented along the fiber axis in the melt spinning shear field to form a rigid nanoskeleton that runs through the polyamide matrix. The polyamide molecular chains are entangled and penetrated in the gaps of the skeleton to form a flexible network.

10. The high abrasion-resistant and tear-resistant nylon fabric for backpacks according to claim 9, characterized in that, The melt spinning process uses a perforated spinneret with 24-96 holes and a hole diameter of 0.25-0.35 mm. The spinning temperature is 250-280℃, the side-blowing velocity is 0.4-0.6 m / s, and the winding speed is 3500-4500 m / min. The resulting multifilament has a fineness of 1.0-2.0 dtex and a breaking strength greater than 5.5 cN / dtex.

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