A wet-spun nylon / PU microfiber synthetic leather base fabric and its preparation method
By using wet spinning and needle punching web forming processes, microfiber synthetic leather base fabric is prepared using nylon 6/66 copolymer and polyurethane, which solves the problems of poor environmental performance and insufficient breathability and moisture permeability in the existing technology, and realizes the production of high-performance microfiber synthetic leather base fabric.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 禾欣可乐丽超纤皮(嘉兴)有限公司
- Filing Date
- 2026-04-02
- Publication Date
- 2026-06-30
AI Technical Summary
Existing microfiber synthetic leather base fabrics have problems in terms of materials, processes and structure, such as poor environmental performance, lack of softness, and insufficient breathability and moisture permeability. Furthermore, traditional melt spinning is difficult to produce nanoscale microfibers.
Using wet spinning technology, nylon 6/66 copolymer and polyurethane are used as raw materials. They are dissolved in DMSO solvent and stretched in a coagulation bath to form ultrafine fibers. Combined with mechanical crimping and needle punching web forming processes, a soft and breathable three-dimensional network structure is prepared.
This process produces a microfiber synthetic leather base fabric that is soft to the touch, breathable and moisture-permeable, and has high mechanical strength. It simplifies the production process, reduces environmental pollution, and improves product performance.
Smart Images
Figure CN122304200A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of synthetic leather materials technology, specifically relating to a wet-spun nylon / PU microfiber synthetic leather base fabric and its preparation method. Background Technology
[0002] Microfiber synthetic leather is an upgraded product of ordinary PU synthetic leather, with performance almost indistinguishable from natural leather. Its core strength lies in its microfiber base fabric, made from island-of-the-sea fibers, possessing a three-dimensional network structure. Currently, mainstream technologies suffer from the following problems: 1) Material limitations: Most island fibers use PET / PA6 as the island and COPET / PE as the sea, and are prepared by melt spinning. PET / PA6 fibers have high rigidity, and there is still room for improvement in the feel, flexibility and bending fatigue performance of the leather made from them. 2) Process limitations: Melt spinning is difficult to produce nanoscale microfibers directly. It is necessary to prepare microfibers by opening up the island fibers. Moreover, the opening of PET and PA6 usually requires the use of strong alkali (NaOH) or toluene, which is not environmentally friendly and damages the fibers. 3) Base fabric structure: Conventional base fabrics are mostly non-woven fabrics that have been impregnated and shaped with PU, which will affect their air permeability and moisture permeability to a certain extent.
[0003] Therefore, developing a microfiber synthetic leather base fabric with a softer feel, better environmental performance, and superior overall performance, as well as its preparation method, is of great significance to the development of the high-end synthetic leather industry. Summary of the Invention
[0004] To address the above problems, the present invention aims to provide a wet-spun nylon / PU microfiber synthetic leather base fabric and its preparation method.
[0005] The specific technical solution is as follows: A method for preparing a wet-spun nylon / PU microfiber synthetic leather base fabric includes the following steps: 1) Preparation of spinning solution: Polyurethane (PU) particles are dissolved in DMSO solvent to prepare a polyurethane solution with a concentration of 15-25 wt%; nylon 6 / 66 copolymer particles are dissolved in DMSO solvent to prepare a nylon solution with a concentration of 8-15 wt%; under high-speed shear stirring at 65-85℃, the nylon solution is slowly added to the polyurethane solution at a mass ratio of nylon 6 / 66 copolymer to polyurethane of 40:60-70:30 to form a uniform, stable, and transparent spinning solution.
[0006] 2) Wet spinning and solidification: After degassing and filtration, the spinning solution obtained in step 1) is transported to the spinneret assembly by a metering pump. The solution extruded from the spinneret immediately enters the coagulation bath and undergoes multi-stage stretching before the fiber is completely solidified. The stretching ratio is 4-15 times. The coagulation bath is a mixed solution of DMSO and water, in which the mass fraction of DMSO is 40%-60% and the bath temperature is controlled at 25-40℃. The solution undergoes double diffusion phase separation in the coagulation bath and solidifies to obtain nascent ultrafine fibers. 3) Post-treatment and fiber crimping: After the nascent microfiber is washed with warm water to remove residual solvent, it is crimped using a mechanical crimping method to increase the fiber's fluffiness and cohesion. After drying, it is cut into short fibers of a fixed length. 4) Reinforcement of fishing nets with needles: The short fibers obtained in step 3) are carded into a web by a carding machine, and then laid into a web of the required weight by a cross-laying machine. The web is then fed into a needle punching machine for pre-punching, main punching, and multiple finishing needle punchings. The needle punching density is 300-1000 needles / cm², which causes the fibers to entangle with each other and form a dense three-dimensional network structure nonwoven fabric, thus obtaining the ultrafine fiber synthetic leather base fabric.
[0007] 5) Iron flat The needle-punched base fabric is ironed to stabilize its dimensions and improve its surface smoothness.
[0008] The beneficial effects of this invention are as follows: 1) It is the first to use flexible nylon 6 / 66 copolymer and polyurethane as raw materials to prepare microfiber by wet spinning, replacing traditional island fiber for the preparation of microfiber base fabric. The resulting base fabric is composed of extremely fine and soft nylon / PU fibers, forming a highly fluffy and porous three-dimensional network. When made into synthetic leather, it has the characteristics of extremely soft and full hand feel, excellent breathability and moisture permeability, high mechanical strength and wrinkle resistance.
[0009] 2) Using DMSO as a co-solvent, it has excellent solubility for two-phase polymers and relatively low toxicity. The DMSO / water coagulation bath system is mild and controllable, and it is easy to form ultrafine fibers with uniform structure. The solvent system used is relatively environmentally friendly, and the fiber opening process causes little damage to the fibers, which is in line with the trend of green manufacturing development.
[0010] 3) Combining wet spinning with needle punching web formation, wet spinning easily produces ultrafine fibers; it eliminates the PU impregnation and weight reduction processes in the traditional preparation of microfiber synthetic leather base fabric, and only uses needle punching and ironing process to retain the pore channels inside the base fabric to the greatest extent, giving it excellent air and moisture permeability, while greatly simplifying the production process. Attached Figure Description
[0011] Figure 1 This is a schematic diagram of the surface structure of the product in Example 1. Detailed Implementation
[0012] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.
[0013] Example 1
[0014] Step 1: Preparation of spinning solution Polyurethane (PU) particles were dissolved in DMSO in a constant temperature water bath at 75°C to prepare a 20 wt% PU solution A. Nylon 6 / 66 copolymer particles were dissolved in DMSO at 70°C to prepare a 10 wt% nylon solution B. Maintaining the temperature at 75°C, nylon solution B was slowly added to PU solution A under high-speed shear stirring, controlling the final mass ratio of nylon 6 / 66 copolymer to polyurethane to be 50:50. The mixture was stirred until a homogeneous, stable, and transparent spinning solution was formed.
[0015] Step 2: Wet spinning and solidification After degassing and filtering, the spinning solution is pumped into the spinneret at a constant rate using a metering pump. The fine stream of solution extruded from the spinneret immediately enters the coagulation bath. The coagulation bath is a mixed solution of DMSO and water, with DMSO comprising 40% by mass, and the bath temperature is controlled at 30°C. While the fiber is passing through the coagulation bath and is not yet fully solidified, it undergoes multi-stage stretching with a total stretching ratio of 8 times, thus solidifying it into nascent ultrafine fibers (0.27D).
[0016] Step 3: Post-treatment and fiber crimping The nascent microfibers were thoroughly washed with 50°C warm water to remove residual DMSO solvent. The fibers were then mechanically crimped to increase their bulk and cohesion. The crimped fibers were dried and cut into short fibers with a length of 51 mm.
[0017] Step 4: Network Formation and Needle Puncture Reinforcement Short fibers are carded into a single-layer fiber web using a carding machine, and then laid out into a fiber web with a basis weight of 500 g / m² using a cross-laying machine. The fiber web is then fed into a needle punching machine, where it undergoes pre-needling, main needle punching, and a finishing needle punching process in sequence. The total needle punching density is set to 600 needles / cm², which allows the fibers to fully entangle and form a dense three-dimensional network structure nonwoven fabric.
[0018] Step 5: Iron flat The needle-punched base fabric is then heat-pressed to stabilize its dimensions and improve surface smoothness, resulting in the microfiber synthetic leather base fabric (softness 5.6 mm, water vapor permeability 3.80 mg / cm²・h, tensile load 434.2 N / 3 cm, tear strength 78.9 N). The product is as follows: Figure 1 As shown.
[0019] Example 2
[0020] Step 1: Preparation of spinning solution Polyurethane (PU) particles were dissolved in DMSO in a constant temperature water bath at 75°C to prepare a 15 wt% PU solution A. Nylon 6 / 66 copolymer particles were dissolved in DMSO at 70°C to prepare an 8 wt% nylon solution B. Maintaining the temperature at 75°C, nylon solution B was slowly added to PU solution A under high-speed shear stirring, controlling the final mass ratio of nylon 6 / 66 copolymer to polyurethane to be 50:50. The mixture was stirred until a homogeneous, stable, and transparent spinning solution was formed.
[0021] Step 2: Wet spinning and solidification After degassing and filtering, the spinning solution is pumped into the spinneret at a constant rate using a metering pump. The fine stream of solution extruded from the spinneret immediately enters the coagulation bath. The coagulation bath is a mixed solution of DMSO and water, with DMSO comprising 50% by mass, and the bath temperature is controlled at 30°C. While the fiber is passing through the coagulation bath and is not yet fully solidified, it undergoes multi-stage stretching with a total stretching ratio of 8 times, thus solidifying it into nascent ultrafine fibers (0.27D).
[0022] Step 3: Post-processing and fiber crimping;
[0023] Step 4: Network formation and needle reinforcement;
[0024] Step 5: Iron flat; Same as in Example 1, the final product was obtained (softness 5.8 mm, water vapor permeability 3.73 mg / cm²・h, tensile load 477.9 N / 3 cm, tear strength 91.5 N).
[0025] Example 3
[0026] Step 1: Preparation of spinning solution Polyurethane (PU) particles were dissolved in DMSO in a constant temperature water bath at 75°C to prepare a 25 wt% PU solution A. Nylon 6 / 66 copolymer particles were dissolved in DMSO at 70°C to prepare a 15 wt% nylon solution B. Maintaining the temperature at 75°C, nylon solution B was slowly added to PU solution A under high-speed shear stirring, controlling the final mass ratio of nylon 6 / 66 copolymer to polyurethane to be 50:50. The mixture was stirred until a homogeneous, stable, and transparent spinning solution was formed.
[0027] Step 2: Wet spinning and solidification After degassing and filtering, the spinning solution is pumped into the spinneret at a constant rate using a metering pump. The fine stream of solution extruded from the spinneret immediately enters the coagulation bath. The coagulation bath is a mixed solution of DMSO and water, with DMSO comprising 60% by mass, and the bath temperature is controlled at 30°C. While the fiber is passing through the coagulation bath and is not yet fully solidified, it undergoes multi-stage stretching with a total stretching ratio of 8 times, thus solidifying it into nascent ultrafine fibers (0.28D).
[0028] Step 3: Post-processing and fiber crimping;
[0029] Step 4: Network formation and needle reinforcement;
[0030] Step 5: Iron flat; Same as in Example 1, the final product was obtained (softness 5.9 mm, water vapor permeability 3.72 mg / cm²・h, tensile load 471.6 N / 3 cm, tear strength 86.8 N).
[0031] Example 4
[0032] Step 1: Preparation of spinning solution Polyurethane (PU) particles were dissolved in DMSO in a constant temperature water bath at 75°C to prepare a 25 wt% PU solution A. Nylon 6 / 66 copolymer particles were dissolved in DMSO at 70°C to prepare a 15 wt% nylon solution B. Maintaining the temperature at 75°C, nylon solution B was slowly added to PU solution A under high-speed shear stirring, controlling the final mass ratio of nylon 6 / 66 copolymer to polyurethane to be 50:50. The mixture was stirred until a homogeneous, stable, and transparent spinning solution was formed.
[0033] Step 2: Wet spinning and solidification After degassing and filtering, the spinning solution is pumped into the spinneret at a constant rate using a metering pump. The fine stream of solution extruded from the spinneret immediately enters the coagulation bath. The coagulation bath is a mixed solution of DMSO and water, with DMSO comprising 70% by mass, and the bath temperature is controlled at 30°C. During the process of the fibers passing through the coagulation bath and before they are fully solidified, multi-stage stretching is performed. During this stretching process, the fibers stick together and break, making it impossible for the preparation process to proceed normally.
[0034] Example 5
[0035] Step 1: Preparation of spinning solution Polyurethane (PU) particles were dissolved in DMSO in a constant temperature water bath at 75°C to prepare a 20 wt% PU solution A. Nylon 6 / 66 copolymer particles were dissolved in DMSO at 70°C to prepare a 10 wt% nylon solution B. Maintaining the temperature at 75°C, nylon solution B was slowly added to PU solution A under high-speed shear stirring, controlling the final mass ratio of nylon 6 / 66 copolymer to polyurethane to be 50:50. The mixture was stirred until a homogeneous, stable, and transparent spinning solution was formed.
[0036] Step 2: Wet spinning and solidification After degassing and filtering, the spinning solution is pumped into the spinneret at a constant rate using a metering pump. The fine stream of solution extruded from the spinneret immediately enters the coagulation bath. The coagulation bath is a mixed solution of DMSO and water, with DMSO comprising 30% by mass, and the bath temperature is controlled at 30°C. While the fiber is passing through the coagulation bath and is not yet fully solidified, it undergoes multi-stage stretching with a total stretching ratio of 8 times, thus solidifying it into nascent ultrafine fibers (0.29D).
[0037] Step 3: Post-processing and fiber crimping;
[0038] Step 4: Network formation and needle reinforcement;
[0039] Step 5: Iron flat; Same as Example 1 (softness 4.1 mm, water vapor permeability 3.77 mg / cm²・h, tensile load 322.7 N / 3 cm, tear strength 62.8 N).
[0040] Example 6
[0041] Step 1: Preparation of spinning solution Polyurethane (PU) particles were dissolved in DMSO in a constant temperature water bath at 75°C to prepare a 25 wt% PU solution A. Nylon 6 / 66 copolymer particles were dissolved in DMSO at 70°C to prepare a 15 wt% nylon solution B. Maintaining the temperature at 75°C, nylon solution B was slowly added to PU solution A under high-speed shear stirring, controlling the final mass ratio of nylon 6 / 66 copolymer to polyurethane to be 50:50. The mixture was stirred until a homogeneous, stable, and transparent spinning solution was formed.
[0042] Step 2: Wet spinning and solidification After degassing and filtering, the spinning solution is pumped into the spinneret at a constant rate using a metering pump. The fine stream of solution extruded from the spinneret immediately enters the coagulation bath. The coagulation bath is a mixed solution of DMSO and water, with DMSO comprising 50% by mass, and the bath temperature is controlled at 30°C. While the fiber passes through the coagulation bath and is not yet fully solidified, it undergoes multi-stage stretching with a total stretching ratio of 4 times, thus solidifying it into nascent ultrafine fibers (0.50D).
[0043] Step 3: Post-processing and fiber crimping;
[0044] Step 4: Network formation and needle reinforcement;
[0045] Step 5: Iron flat Same as Example 1 (softness 6.1 mm, water vapor permeability 3.84 mg / cm²・h, tensile load 395.5 N / 3 cm, tear strength 77.6 N).
[0046] Example 7
[0047] Step 1: Preparation of spinning solution Polyurethane (PU) particles were dissolved in DMSO in a constant temperature water bath at 75°C to prepare a 25 wt% PU solution A. Nylon 6 / 66 copolymer particles were dissolved in DMSO at 70°C to prepare a 15 wt% nylon solution B. Maintaining the temperature at 75°C, nylon solution B was slowly added to PU solution A under high-speed shear stirring, controlling the final mass ratio of nylon 6 / 66 copolymer to polyurethane to be 50:50. The mixture was stirred until a homogeneous, stable, and transparent spinning solution was formed.
[0048] Step 2: Wet spinning and solidification After degassing and filtering, the spinning solution is pumped into the spinneret at a constant rate using a metering pump. The fine stream of solution extruded from the spinneret immediately enters the coagulation bath. The coagulation bath is a mixed solution of DMSO and water, with DMSO comprising 50% by mass, and the bath temperature is controlled at 30°C. While the fiber is passing through the coagulation bath and is not yet fully solidified, it undergoes multi-stage stretching with a total stretch ratio of 15 times, thus solidifying it into nascent ultrafine fibers (0.14D).
[0049] Step 3: Post-processing and fiber crimping;
[0050] Step 4: Network formation and needle reinforcement;
[0051] Step 5: Iron flat; Same as Example 1 (softness 5.6 mm, water vapor permeability 3.91 mg / cm²・h, tensile load 488.7 N / 3 cm, tear strength 90.7 N).
[0052] The invention obtained in Examples 1-7 Table 1 shows the performance test results of microfiber synthetic leather base fabric and conventional microfiber synthetic leather base fabric of the same basis weight (XC product). Data from Examples 1-5 in the table show that microfiber synthetic leather base fabrics prepared with a DMSO mass fraction of 40%-60% in the coagulation bath exhibit excellent softness, water vapor permeability, and mechanical properties. When the DMSO mass fraction in the coagulation bath is 70%, the concentration difference between the coagulation bath and the spinning solution is small, resulting in insufficient coagulation driving force, incomplete coagulation of the spinning solution, a gel-like state, and filament agglomeration. This leads to insufficient physical strength and makes it unsuitable for the normal preparation of microfiber synthetic leather base fabric. When the DMSO mass fraction in the coagulation bath is 30%, the concentration difference between the coagulation bath and the spinning solution is large, causing the fiber surface to coagulate too quickly, forming a dense, inelastic, and brittle skin layer. This hinders internal double diffusion, leading to uneven structure, poor fiber extensibility during coagulation and stretching, and the appearance of fuzz. This results in lower softness and mechanical properties in the final product, making it unsuitable for the preparation of microfiber synthetic leather base fabric. Data from Examples 2, 6, and 7 in the table show that a lower coagulation stretch ratio results in coarser fibers, leading to higher softness and lower mechanical properties in the final microfiber synthetic leather base fabric. Conversely, a higher coagulation stretch ratio results in finer fibers, leading to lower softness and higher mechanical properties in the final microfiber synthetic leather base fabric. A comparison of the performance data from the examples and XC products in the table reveals that the product of this invention outperforms conventional microfiber synthetic leather base fabrics of the same weight in terms of softness, water vapor permeability, and mechanical properties.
[0053] Table 1 Comparison of Product Performance in Examples XC products Case 1 Case 2 Case 3 Case 4 Case 5 Case 6 Case 7 Mass ratio of nylon 6 / 66 copolymer to polyurethane / 50:50 50:50 50:50 50:50 50:50 50:50 50:50 Mass fraction (%) of DMSO in the coagulation bath / 40 50 60 70 30 50 50 Solidification stretch ratio (times) / 8 8 8 8 8 4 15 Stretched hair / no no no no yes no no Stretching, adhesion, and broken filaments / no no no yes no no no Fineness (D) / 0.27 0.27 0.28 / 0.29 0.50 0.14 Softness (mm) 5.5 5.6 5.8 5.9 / 4.1 6.1 5.6 Water vapor permeability (mg / cm²・h) 1.26 3.80 3.73 3.72 / 3.77 3.84 3.91 Tensile load (N / 3cm) 379.4 434.2 477.9 471.6 / 322.7 395.5 488.7 Tear strength (N) 75.8 78.9 91.5 86.8 / 62.8 77.6 90.7
Claims
1. A method for preparing a wet-spun nylon / PU microfiber synthetic leather base fabric, characterized in that, Includes the following steps: 1) A spinning solution was prepared using nylon 6 / 66 copolymer and polyurethane as raw materials and DMSO as solvent; 2) The spinning solution in step 1) is subjected to wet spinning, formed in a coagulation bath of a DMSO and water mixture, and post-processed to obtain ultrafine short fibers. 3) The ultrafine short fibers from step 2) are then combed, laid into a web, needle-punched and reinforced, and ironed to obtain ultrafine fiber synthetic leather base fabric.
2. The method for preparing a wet-spun nylon / PU microfiber synthetic leather base fabric as described in claim 1, characterized in that, In step 1), the mass ratio of nylon 6 / 66 copolymer to polyurethane is 40:60-70:
30.
3. The method for preparing a wet-spun nylon / PU microfiber synthetic leather base fabric as described in claim 1, characterized in that, In step 2), the mass fraction of DMSO in the DMSO and water mixture is 40-60%.
4. The method for preparing a wet-spun nylon / PU microfiber synthetic leather base fabric as described in claim 1, characterized in that, The needle density for acupuncture reinforcement in step 3) is 300-1000 needles / cm².
5. The method for preparing a wet-spun nylon / PU microfiber synthetic leather base fabric as described in claim 1, characterized in that, In step 2), the fibers are stretched by 4.0-15.0 times before they are fully cured. The post-processing includes washing, crimping, drying and cutting the fibers into short fibers.
6. A wet-spun nylon / PU microfiber synthetic leather base fabric prepared by any one of the preparation methods described in claims 1-5, characterized in that, The microfiber synthetic leather base fabric is a three-dimensional network structure formed by needle punching and entanglement of nylon 6 / 66 and polyurethane microfibers.