Wet preparation method of microfiber Yangbuck composite material for waterproof and breathable shoes

Abstract

The invention discloses a wet preparation method of a microfiber Yangbuck composite material for waterproof and breathable shoes. The wet preparation method is characterized by comprising the following steps: step 1, preparing slurry; step 2, pretreating the base cloth; step 3, coating the slurry; step 4, wet solidification; step 5, water washing treatment; step 6, waterproof treatment; step 7, drying, foaming and shaping; and 8, cooling and rolling. According to the invention, a micron-sized porous structure is formed through a wet solidification process, and through cooperation with the synergistic effect of the pore-forming agent, the air permeability of the material is more than or equal to 500g / (m < 2 >. 24h), and meanwhile, the hydrostatic pressure is more than or equal to 30kPa, so that external moisture permeation is effectively blocked, moisture in shoes can be quickly discharged, and the core pain point that the traditional synthetic leather for shoes is waterproof and airtight or breathable and not waterproof is thoroughly solved.

Description

Technical Field

[0001] This invention belongs to the field of synthetic leather technology, and specifically relates to a wet preparation method of a waterproof and breathable microfiber sheepskin composite material for shoes. Background Technology

[0002] While genuine leather products possess a natural texture and excellent properties, their high price due to resource scarcity makes it difficult to meet the large-scale demand of the mass market. Against this backdrop, artificial leather products have developed rapidly. Among them, parfum resin, with its fluffy surface and velvety texture created by high-temperature expansion and foaming, occupies an important position in the leather market. Combined with subsequent processes, it can be made into artificial leather that has the feel of genuine leather.

[0003] In existing technologies, conventional thermally expandable microspheres are easily soluble in organic solvents such as DMF. Therefore, most authorized patents for preparing sheepskin using thermally expandable microspheres employ a dry-printing process, printing the microspheres onto a dry layer. Addressing the technological gap in wet-process sheepskin preparation, this project utilizes solvent-resistant thermally expandable microspheres that do not dissolve in DMF. Furthermore, it innovatively incorporates "solvent-resistant thermally expandable microspheres (foaming agent)" and "low-migration retro dye" into the wet coating slurry formulation. By precisely adjusting the scraper speed and oven temperature, the coating simultaneously completes foaming (creating a sheepskin suede feel) and dyeing (presenting an antique tone) during film formation, eliminating the need for subsequent separate brushing or dyeing processes. Developing a method for preparing a high-performance waterproof and breathable microfiber sheepskin composite material for footwear is of significant practical importance in meeting consumers' higher quality demands for footwear products. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a wet preparation method for waterproof and breathable microfiber sheepskin composite material for shoes. The wet coagulation process forms a micron-level porous structure, which, in conjunction with the synergistic effect of a pore-forming agent, effectively blocks external moisture penetration and quickly expels moisture from inside the shoe, thus completely solving the core pain points of traditional synthetic leather for shoes that are either "waterproof but not breathable" or "breathable but not waterproof".

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A wet preparation method for a waterproof and breathable microfiber sheepskin composite material for footwear includes the following steps:

[0007] Step 1, Slurry preparation: Take high-performance polyether resin, add solvent DMF, and stir to adjust to a suitable viscosity; then add pore-forming agent starch, low-migration retro dye, filler, additives and solvent-resistant thermal foaming capsules in sequence, stir at high speed until uniform, filter, and finally degas under vacuum to obtain a uniform and bubble-free polyurethane surface slurry.

[0008] Step 2, base fabric pretreatment: Immerse the nonwoven fabric in a DMF solution with a concentration of 50-65% for impregnation treatment, and then place the impregnated base fabric on a moisture conditioning roller at 70-90℃ for 2-5 minutes to complete the base fabric pre-conditioning.

[0009] Step 3, Slurry Coating: A polyurethane topcoat slurry that has undergone degassing treatment is applied to the pre-conditioned base fabric surface using a coating machine;

[0010] Step 4, wet coagulation: Immerse the base fabric coated with slurry into a coagulation tank with a DMF solution at a temperature of 20-35℃ and a concentration of 15-25% to allow the surface slurry to fully coagulate and form a film.

[0011] Step 5, water washing treatment: Place the solidified film fabric in water at 50-80℃ for rolling and washing, repeat the rolling and washing to thoroughly clean and remove the residual DMF solvent inside the fabric.

[0012] Step 6, Waterproofing treatment: Immerse the washed film in a solution of hexadecyltrimethoxysilane and anhydrous ethanol in a 1:1 ratio and roll it again. During this process, the fabric is in complete contact with the solution, forming a hydrophobic layer on the surface of the fabric.

[0013] Step 7, Drying, Foaming and Setting: The washed fabric is first placed in an oven at 115-135℃ for drying; then transferred to an oven at 150-170℃ for drying to complete the foaming process; the oven adopts a segmented temperature control mode, with the first segment at 115-135℃ to promote solvent evaporation, the middle segment at 150-170℃ to trigger the thermal expansion of microspheres for foaming, and the last segment at 135-140℃ to dry and fix the dye color;

[0014] Step 8, Cooling and Rolling: The dried, foamed and shaped composite material is naturally cooled to room temperature, and then rolled up to form a large roll of semi-finished product, which is the waterproof and breathable microfiber sheepskin composite material for shoes.

[0015] In the above technical solution, in step 1, the filler is CaCO3 and lignocellulose, and the auxiliary agent is defoamer, penetrant, and desolvation agent.

[0016] In the above technical solution, in step 1, by weight fraction, there are 100 parts of solvent DMF, 100 parts of resin, 0.5-2 parts of solvent-resistant thermal foaming capsule, 0.5-2 parts of pore-forming agent starch, 0.5-2 parts of low-migration retro dye, 10-30 parts of filler, and 0.5-2 parts of additives.

[0017] In the above technical solution, in step 1, the stirring speed is 2500-3000 r / min, the stirring time is 30-50 minutes, and the vacuum degassing time is 40-60 minutes.

[0018] In the above technical solution, in step 3, the amount of sizing is controlled to be 50-100 s on the fabric surface, and the scraper speed is adjusted to 5-10 m / min.

[0019] The beneficial effects of this invention are as follows:

[0020] (1) Strong process innovation and significantly improved efficiency: In the wet coating slurry formulation, "solvent-resistant thermal expansion microspheres (foaming agent)" and "low migration retro dye" are innovatively compounded. By precisely controlling the doctor blade speed (5-10 m / min) and the oven segmented temperature (solvent evaporation in the first segment, microsphere foaming in the middle segment, and dye fixation in the last segment), the coating can complete foaming and flocking and dyeing simultaneously during the film formation process, completely eliminating the separate flocking and dyeing processes in the traditional process, increasing production efficiency by more than 30%, and avoiding the damage to the flocked texture caused by post-processing.

[0021] (2) Excellent synergy between waterproofing and breathability: The micron-scale porous structure is formed through wet solidification process, and with the synergistic effect of pore-forming agent, the air permeability of the material is ≥500 g / (m²). 2 • 24h), while the hydrostatic pressure is ≥30 kPa, which not only effectively blocks external moisture penetration, but also quickly removes moisture from inside the shoe, completely solving the core pain points of traditional synthetic leather for shoes that are either "waterproof but not breathable" or "breathable but not waterproof".

[0022] (3) Combining feel and durability: The product uses Hexin Kuraray non-woven fabric as the base and PU porous structure composite, combined with solvent-resistant thermal expansion microsphere foam to form delicate fluff, the product has a soft feel and is close to natural sheepskin; according to the test, the material Martindale has an abrasion resistance of ≥50,000 revolutions, a low temperature folding resistance of ≥10,000 times at -20℃ without cracking, and also has excellent aging resistance, is not easy to mold, and is fully suitable for the long-term use of shoe materials.

[0023] (4) Excellent dimensional stability: By impregnating with 50-65% DMF solution and pre-treating with 70-90℃ humidity rollers, combined with precise control of wet coagulation and segmented drying, the shrinkage rate of the composite material is ≤2%, which makes it less prone to deformation during shoe material processing such as cutting and sewing, and significantly reduces the scrap rate. Detailed Implementation

[0024] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below in conjunction with specific embodiments. This invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art. This invention will be defined only by the claims.

[0025] This invention provides a wet-process preparation method for a waterproof and breathable microfiber sheepskin composite material for footwear. The composite material consists of a double-layer structure: 1-outer skin layer (coating layer); 2-base material (backing fabric layer), wherein the backing fabric is a non-woven fabric produced by Hexin Kuraray. The air permeability of the composite material is ≥500g / (m²). 2 • 24h), hydrostatic pressure ≥30kPa, Martindale abrasion resistance ≥50000 revolutions, -20℃ low temperature flexural resistance ≥10000 cycles without cracking, shrinkage rate ≤2%.

[0026] Process flow: Base fabric unwinds → enters the impregnation tank through the fabric storage rack for wetting → squeeze rollers squeeze out most of the water → ironing rollers remove water and iron the base fabric → coating machine applies slurry → coagulation tank forms a film → thorough washing → drying and shaping → cooling into large roll semi-finished product.

[0027] The method for preparing the composite material of the present invention includes the following steps:

[0028] Step 1, Slurry preparation: Take high-performance polyether resin (e.g., resins HX-3020K and HX-3060K produced by Hexin Technology), add DMF solvent, and stir to adjust to a suitable viscosity; then add pore-forming agent starch, low-migration retro dye, filler (CaCO3 and lignocellulose), additives (defoamer, penetrant, desolvating agent) and solvent-resistant thermal foaming capsules in sequence, stir at high speed until uniform, filter, and finally degas under vacuum for 40-60 min to obtain a uniform and bubble-free polyurethane surface layer slurry.

[0029] Table 1 Slurry Formulation

[0030] Step 2, Base fabric pretreatment: Immerse the nonwoven fabric produced by Hexin Kuraray in a DMF solution with a concentration of 50-65% for impregnation treatment, and then place the impregnated base fabric on a moisture conditioning roller at 70-90℃ for 2-5 minutes to complete the base fabric pre-conditioning.

[0031] Step 3, Slurry Coating: Use a coating machine to apply the defoamed polyurethane surface layer slurry to the pre-conditioned base fabric surface, controlling the slurry application amount to be 50-100 s on the fabric surface, while adjusting the scraper speed to 5-10 m / min.

[0032] Step 4, wet coagulation: Immerse the base fabric coated with slurry into a coagulation tank with a DMF solution at a temperature of 20-35℃ and a concentration of 15-25% to allow the surface slurry to fully coagulate and form a film.

[0033] Step 5, Water washing treatment: Place the solidified film in water at 50-80℃ for rolling and washing, repeating the rolling and washing 15-25 times to thoroughly clean and remove the residual DMF solvent inside the fabric. During this process, the starch is also removed in the water, leaving a micron-sized porous structure in the film. The high porosity is beneficial for achieving good air permeability during use.

[0034] Step 6, Waterproofing Treatment: The washed film is immersed again in a solution of hexadecyltrimethoxysilane and anhydrous ethanol in a 1:1 ratio. During this process, the fabric is in complete contact with the solution, forming a hydrophobic layer on the fabric surface.

[0035] Step 7, Drying, Foaming, and Setting: The washed fabric is first placed in an oven at 115-135℃ for 3-6 minutes; then transferred to an oven at 150-170℃ for 2-4 minutes to complete the foaming process. The oven uses a segmented temperature control mode: the first segment at 115-135℃ promotes solvent evaporation, the middle segment at 150-170℃ triggers the foaming of thermally expanded microspheres, and the final segment at 135-140℃ for 1-2 minutes fixes the dye color. Simultaneously, at high temperature, hexadecyltrimethoxysilane reacts completely with the polyurethane to form a stable cross-linked structure.

[0036] Step 8, Cooling and Rolling: The dried, foamed and shaped composite material is naturally cooled to room temperature, and then rolled up to form a large roll of semi-finished product, which is the waterproof and breathable microfiber sheepskin composite material for shoes. Example 1

[0037] 1. Slurry preparation: Take 50 parts of HX-3020K resin and 50 parts of HX-3060K resin, add 100 parts of DMF solvent, and stir to adjust the viscosity to 3000 mPa·s; add 0.5 parts of starch, 0.5 parts of dye, 10 parts of CaCO3, 10 parts of lignocellulose, 0.2 parts of defoamer, 0.2 parts of penetrant, 0.1 parts of desolvating agent and 0.5 parts of solvent-resistant thermal foaming capsule in sequence, stir at high speed of 2500 r / min for 30 minutes, filter and degas under vacuum for 40 minutes to obtain slurry.

[0038] 2. Base fabric pretreatment: Immerse the Hexin Kuraray microfiber base fabric in a 50% DMF solution, and then treat it on a 70℃ humidity conditioning roller for 5 minutes.

[0039] 3. Coating: Doctor blade speed 8 m / min, sizing amount 80s.

[0040] 4. Coagulation: 20℃ coagulation bath, DMF concentration 15%.

[0041] 5. Washing: Wash 15 times with water at 50℃.

[0042] 6. Drying and foaming: Dry at 115℃ for 6 minutes, foam at 150℃ for 4 minutes; the oven temperature is controlled in sections at 125℃, 160℃ and 135℃.

[0043] 7. Performance Test: Air permeability 520g / (m²) 2 • 24h), hydrostatic pressure 32kPa, Martindale abrasion resistance 51000 revolutions, 1050 folding cycles at -20℃ without cracking, shrinkage rate 1.8%. Example 2

[0044] 1. Slurry preparation: Take 50 parts of HX-3020K resin and 50 parts of HX-3060K resin, add 100 parts of DMF solvent, and stir to adjust the viscosity to 4000 mPa·s; add 1 part of starch, 1 part of dye, 10 parts of CaCO3, 10 parts of lignocellulose, 0.3 parts of defoamer, 0.3 parts of penetrant, 0.4 parts of desolvating agent and 1 part of solvent-resistant thermal foaming capsule in sequence, stir at high speed of 2800 r / min for 40 minutes, filter and degas under vacuum for 40 minutes to obtain slurry.

[0045] 2. Base fabric pretreatment: Immerse the Hexin Kuraray microfiber base fabric in a 58% DMF solution, and then treat it on an 80℃ humidity conditioning roller for 3 minutes.

[0046] 3. Coating: Doctor blade speed 8m / min, sizing amount 80s.

[0047] 4. Coagulation: 28℃ coagulation bath, DMF concentration 20%.

[0048] 5. Washing: Wash 20 times with water at 65℃.

[0049] 6. Drying and foaming: Dry at 125℃ for 4 minutes, foam at 160℃ for 3 minutes; the oven temperature is controlled in sections at 125℃, 160℃ and 135℃.

[0050] 7. Performance test: Air permeability 550 g / (m²) 2 • 24h), hydrostatic pressure 35kPa, Martindale abrasion resistance 55000 revolutions, 11000 folding cycles at -20℃ without cracking, shrinkage rate 1.5%. Example 3

[0051] 1. Slurry preparation: Take 50 parts of HX-3020K resin and 50 parts of HX-3060K resin, add 100 parts of DMF solvent, and stir to adjust the viscosity to 5000 mPa·s; add 2 parts of starch, 2 parts of dye, 10 parts of CaCO3, 10 parts of lignocellulose, 0.5 parts of defoamer, 0.5 parts of penetrant, 0.5 parts of desolvating agent, and 2 parts of solvent-resistant thermal foaming capsules in sequence, stir at 3000r / min for 50 minutes, filter, and degas under vacuum for 40 minutes to obtain the slurry.

[0052] 2. Base fabric pretreatment: Immerse the Hexin Kuraray microfiber base fabric in a 65% DMF solution, and then treat it on a 90℃ humidity conditioning roller for 2 minutes.

[0053] 3. Coating: Doctor blade speed 8 m / min, sizing amount 80s.

[0054] 4. Coagulation: 35℃ coagulation bath, DMF concentration 25%.

[0055] 5. Washing: Wash 25 times with water at 80℃.

[0056] 6. Drying and foaming: Dry at 135℃ for 3 minutes, foam at 170℃ for 2 minutes; the oven temperature is controlled in sections at 125℃, 160℃ and 135℃.

[0057] 7. Performance Test: Air permeability 580g / (m²) 2 • 24h), hydrostatic pressure 38kPa, Martindale abrasion resistance 58000 revolutions, 12000 folding cycles at -20℃ without cracking, shrinkage rate 1.2%.

[0058] Comparative Example 1 (without solvent-resistant thermal expansion microspheres)

[0059] Conventional thermally expandable microspheres were used instead of solvent-resistant thermally expandable microspheres, with the remaining raw materials and process parameters the same as in Example 2. Results showed that the conventional thermally expandable microspheres dissolved in DMF, resulting in stratification of the slurry and failure to form a uniform coating; the final product lacked a velvety texture, and its air permeability was only 200 g / (m³). 2 • 24h), hydrostatic pressure 20kPa, the performance is significantly inferior to that of the present invention.

[0060] Comparative Example 2 (Traditional post-brushing dyeing process)

[0061] No thermally expanded microspheres or colorants were added to the sizing. After preparing the fabric using a traditional wet process, additional napping (using 800-grit sandpaper) and dyeing treatments were performed, with other parameters the same as in Example 2. Results showed that the product had uneven pile length and a rough feel; the production cycle was extended by 40%, and the scrap rate increased to 15%; the air permeability was 450 g / (m²). 2 •24h), hydrostatic pressure 32 kPa, overall performance is lower than that of this invention.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A wet preparation method for a waterproof and breathable microfiber sheepskin composite material for shoes, characterized in that: Includes the following steps: Step 1, Slurry preparation: Take high-performance polyether resin, add solvent DMF, and stir to adjust to a suitable viscosity; then add pore-forming agent starch, low-migration retro dye, filler, additives and solvent-resistant thermal foaming capsules in sequence, stir at high speed until uniform, filter, and finally degas under vacuum to obtain a uniform and bubble-free polyurethane surface slurry. Step 2, base fabric pretreatment: Immerse the nonwoven fabric in a DMF solution with a concentration of 50-65% for impregnation treatment, and then place the impregnated base fabric on a moisture conditioning roller at 70-90℃ for 2-5 minutes to complete the base fabric pre-conditioning. Step 3, Slurry Coating: A polyurethane topcoat slurry that has undergone degassing treatment is applied to the pre-conditioned base fabric surface using a coating machine; Step 4, wet coagulation: Immerse the base fabric coated with slurry into a coagulation tank with a DMF solution at a temperature of 20-35℃ and a concentration of 15-25% to allow the surface slurry to fully coagulate and form a film. Step 5, water washing treatment: Place the solidified film fabric in water at 50-80℃ for rolling and washing, repeat the rolling and washing to thoroughly clean and remove the residual DMF solvent inside the fabric. Step 6, Waterproofing treatment: Immerse the washed film in a solution of hexadecyltrimethoxysilane and anhydrous ethanol in a 1:1 ratio and roll it again. During this process, the fabric is in complete contact with the solution, forming a hydrophobic layer on the surface of the fabric. Step 7, Drying, Foaming and Setting: The washed fabric is first placed in an oven at 115-135℃ for drying; then transferred to an oven at 150-170℃ for drying to complete the foaming process; the oven adopts a segmented temperature control mode, with the first segment at 115-135℃ to promote solvent evaporation, the middle segment at 150-170℃ to trigger the thermal expansion of microspheres for foaming, and the last segment at 135-140℃ to dry and fix the dye color; Step 8, Cooling and Rolling: The dried, foamed and shaped composite material is naturally cooled to room temperature, and then rolled up to form a large roll of semi-finished product, which is the waterproof and breathable microfiber sheepskin composite material for shoes.

2. The wet preparation method according to claim 1, characterized in that: In step 1, the filler is CaCO3 and lignocellulose, and the additives are defoamer, penetrant, and desolvation agent.

3. The wet preparation method according to claim 1, characterized in that: In step 1, by weight fraction, there are 100 parts of solvent DMF, 100 parts of resin, 0.5-2 parts of solvent-resistant thermal foaming capsule, 0.5-2 parts of pore-forming agent starch, 0.5-2 parts of low-migration retro dye, 10-30 parts of filler, and 0.5-2 parts of additives.

4. The wet preparation method according to claim 1, characterized in that: In step 1, the stirring speed is 2500-3000 r / min, the stirring time is 30-50 minutes, and the vacuum degassing time is 40-60 minutes.

5. The wet preparation method according to claim 1, characterized in that: In step 3, the amount of sizing is controlled to be 50-100 s on the fabric surface, while the doctor blade speed is adjusted to 5-10 m / min.

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