Preparation process of high-strength full-environment-friendly water-soluble water-based shoe leather

Abstract

The invention discloses a preparation process of high-strength full-environment-friendly water-soluble water-based shoe leather, a water-soluble water-based non-woven fabric is subjected to wet impregnation by adopting a water-based polyurethane working emulsion, and the water-based polyurethane working emulsion is prepared from 100 parts of first water-based aromatic polyurethane resin, 0.3-1.2 parts of a thickening agent and 1-1.5 parts of an anionic penetrant; a citric acid solution is used for acid solidification, hot water splitting, drying, oiling and leather rubbing are conducted, and a water-soluble waterborne polyurethane base is obtained; a surface material layer and a bottom material layer are sequentially arranged on release paper in a blade coating mode, the surface material layer is prepared from 100 parts of second waterborne aromatic polyurethane resin and 0.3-1.2 parts of a thickening agent, and the bottom material layer is prepared from 100 parts of thermal activation type waterborne polyurethane resin and 0.5-1.5 parts of a thickening agent; and compounding the bottom material layer and the water-soluble waterborne polyurethane base to obtain the high-strength full-environment-friendly water-soluble waterborne shoe leather. Through cooperation of the anionic penetrant, the acid solidification and the thermal activation type waterborne polyurethane resin, the mechanical property, the structural stability and the environmental protection property of the shoe leather are integrally improved, and the requirements of high-end shoe materials are met.

Description

Technical Field

[0001] This invention relates to the field of synthetic leather technology, specifically to a preparation process for high-strength, fully environmentally friendly, water-soluble, water-based shoe leather. Background Technology

[0002] With the development of synthetic leather technology, environmentally friendly water-based shoe leather has received widespread attention due to its non-toxicity and low VOC emissions. However, existing water-based shoe leather still has significant shortcomings in terms of mechanical properties, processing adaptability, and usage stability. 1. Insufficient mechanical properties: Traditional water-based shoe leather has poor flexural strength and is prone to white marks or cracks in low-temperature environments; it has low peel strength and tear strength and is prone to delamination or damage.

[0003] 2. Poor Processing Adaptability: During the drying process of dispersions, since moisture can only evaporate from its surface, the evaporation will inevitably cause some areas to concentrate, resulting in uneven concentration. Latex drying experiments have shown that uneven particle distribution during latex drying can occur in both vertical and horizontal directions. Uneven distribution in the vertical direction is called vertical drying, and uneven distribution in the horizontal direction is called horizontal drying. Existing technologies for preparing shoe leather are prone to coating cracking and roughness due to uneven moisture evaporation during the drying process, affecting the uniformity and appearance of the finished product.

[0004] 3. Low bonding strength: When using conventional water-based resin veneer, the base layer does not bond firmly to the sole layer, affecting the overall durability of the shoe leather.

[0005] Therefore, there is an urgent need for a water-based shoe leather manufacturing process that combines high strength, high stability, and complete environmental friendliness to solve the above problems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a preparation process for high-strength, fully environmentally friendly water-soluble footwear leather. By synergistically combining anionic penetrants, acid coagulation, and thermally activated water-based polyurethane resin, the mechanical properties, structural stability, and environmental friendliness of the footwear leather are comprehensively improved, meeting the demands of high-end footwear materials.

[0007] To achieve the above objectives, the present invention provides a preparation process for high-strength, fully environmentally friendly, water-soluble, water-based shoe leather, comprising the following steps: S1: Wet impregnation: A water-soluble water-based nonwoven fabric is wet impregnated with a water-based polyurethane working emulsion to obtain an impregnated base fabric. The water-based polyurethane working emulsion is prepared from 100 parts of a first water-based aromatic polyurethane resin, 0.3-1.2 parts of a polyurethane associative thickener, and 1-1.5 parts of anionic penetrant. S2: Acid coagulation: The impregnated base fabric is acid coagulated using a citric acid solution; S3: The acid-coagulated base fabric is subjected to hot water fiber opening, drying, oiling, and rubbing to obtain water-soluble waterborne polyurethane base; S4: Dry lamination: A top layer and a bottom layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second water-based aromatic polyurethane resin and 0.3-1.2 parts of a polyurethane associative thickener. The bottom layer is made of 100 parts of a thermally activated water-based polyurethane resin and 0.5-1.5 parts of a polyurethane associative thickener. The bottom layer is then combined with a water-soluble water-based polyurethane base to obtain the high-strength, fully environmentally friendly water-soluble water-based shoe leather.

[0008] Further, in S1, the water-soluble nonwoven fabric comprises 65-75% nylon and 25-35% PVA; the basis weight is 500-700 g / m². 2 Width ≥ 148cm.

[0009] Furthermore, in S1, the anionic penetrant is sodium diisooctyl succinate sulfonate.

[0010] Furthermore, the first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity of ≤1000cps, a modulus of 1.2MPa, a tensile strength of ≥5MPa, and an elongation of ≥800%.

[0011] Furthermore, the preparation process of the waterborne polyurethane working emulsion is as follows: weigh an appropriate amount of first waterborne aromatic polyurethane resin, polyurethane associative thickener, and anionic penetrant and add them to the reaction vessel. Stir at a mixer speed of 2300-4300 r / min for 40-60 min, and control the viscosity at 2000-4000 cps to obtain the waterborne polyurethane working emulsion.

[0012] Furthermore, in S2, the impregnated base fabric is prepared using a 13-20% citric acid solution and solidified at 25-30°C for 15-25 minutes.

[0013] Furthermore, in S4, the activation temperature of the thermally activated waterborne polyurethane resin is 50-55℃, the solid content is 50±2%, the pH value is 6.0~8.0, and the viscosity is 100-300cps.

[0014] Furthermore, the second waterborne aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0 to 8.0, a viscosity of 3500±1000 cps, a modulus of 3.0 to 4.5 MPa, a tensile strength of ≥10 MPa, and an elongation of ≥300%.

[0015] Furthermore, the solid content of the polyurethane associative thickener is 40±2%.

[0016] Furthermore, the coating thickness of the fabric layer is 10-18 mils, the drying temperature is 110-130℃, and the drying time is 2-3 minutes; the coating thickness of the base layer is 20-25 mils, the drying temperature is 80-100℃, and the drying time is 5-10 minutes; after the base layer is compounded with water-soluble polyurethane base, it is dried at 120-140℃ for 5-8 minutes to obtain the high-strength, fully environmentally friendly water-soluble leather.

[0017] The preparation process of the high-strength, fully environmentally friendly, water-soluble, water-based shoe leather of this invention has the following beneficial technical effects: 1. By adding anionic penetrants to waterborne polyurethane working emulsions, the permeability and uniformity can be improved during processing, promoting better penetration and distribution of various additives and chemical agents, avoiding local unevenness. In this process, water-soluble water-based agents are used to reduce the surface tension of water in the system, change the evaporation rate of water during drying, thereby improving uneven horizontal and vertical drying, and enhancing overall uniformity and a certain degree of mechanical properties.

[0018] 2. By using citric acid solution for acid coagulation, the cross-linking of polyurethane molecules can be promoted to form a dense three-dimensional network structure, which significantly improves strength, flexural strength, environmental adaptability and processability.

[0019] 3. By using heat-activated waterborne polyurethane resin as the base layer for dry bonding, the product is endowed with excellent initial tack and final bonding strength, completely solving the technical problems of poor adhesion and folding resistance of waterborne base bonding.

[0020] 4. Therefore, this invention, through the synergistic effect of "anionic penetrant," "acid coagulation," and "thermally activated waterborne polyurethane resin," comprehensively improves the mechanical properties, structural stability, and environmental friendliness of shoe leather, meeting the demands of high-end shoe materials. The addition of the anionic penetrant improves the permeability and drying uniformity of the working emulsion, preventing coating cracking and solving the problem of poor processing compatibility. The synergistic effect of acid coagulation and thermally activated polyurethane resin significantly enhances the mechanical properties of the shoe leather, particularly flexural strength and peel strength, solving the problem of insufficient mechanical properties. Using thermally activated waterborne polyurethane resin as the base layer provides strong initial tack and final adhesive strength, solving the problem of low adhesive strength. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a preparation process for high-strength, fully environmentally friendly, water-soluble, water-based shoe leather, comprising the following steps: S1: Wet Impregnation: A water-soluble water-based nonwoven fabric is wet impregnated with a water-based bio-based polyurethane working emulsion to obtain an impregnated base fabric. The water-based bio-based polyurethane working emulsion is prepared by 100 parts of a first water-based aromatic polyurethane resin, 0.3-1.2 parts of a polyurethane associative thickener, and 1-1.5 parts of anionic penetrant. The preparation process of the water-based bio-based polyurethane working emulsion is as follows: Weigh an appropriate amount of the first water-based aromatic polyurethane resin, polyurethane associative thickener, and anionic penetrant and add them to a reaction vessel. Stir at a stirring speed of 2300-4300 r / min for 40-60 min, and control the viscosity at 2000-4000 cps to obtain the water-based bio-based polyurethane working emulsion.

[0023] S2: Acid coagulation: The impregnated base fabric is coagulated at 25-30℃ for 15-25 minutes using a 13-20% citric acid solution.

[0024] S3: The base fabric after acid coagulation is subjected to hot water fiber opening, drying, oiling, and kneading to obtain water-soluble waterborne polyurethane base.

[0025] S4: Dry lamination: A top layer and a bottom layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second water-based aromatic polyurethane resin and 0.3-1.2 parts of a polyurethane associative thickener. The bottom layer is made of 100 parts of a thermally activated water-based polyurethane resin and 0.5-1.5 parts of a polyurethane associative thickener. The bottom layer is then combined with a water-soluble water-based polyurethane base to obtain the high-strength, fully environmentally friendly water-soluble water-based shoe leather.

[0026] In S1, the water-soluble nonwoven fabric comprises 65-75% nylon and 25-35% PVA; the basis weight is 500-700 g / m². 2 Nylon nonwoven fabric with a width ≥ 148cm was purchased from Ningbo Hengqide Chemical Fiber Technology Co., Ltd.

[0027] In S1, the anionic penetrant is sodium diisooctyl succinate sulfonate, which is purchased from Hubei Haishihua New Materials Co., Ltd. as sodium diisooctyl succinate sulfonate OT-75. It is a colorless to light yellow liquid with a solid content of 75±1% and a pH of 5.0-7.0, using ethanol as a solvent.

[0028] The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity of ≤1000cps, a modulus of 1.2MPa, a tensile strength of ≥5MPa, and an elongation of ≥800%. It is KT735F waterborne polyurethane resin purchased from Hefei Ketian Waterborne Technology Co., Ltd.

[0029] In S3, hot water fiber opening removes water-soluble components from the impregnated base fabric through hot water immersion and pressing, achieving weight reduction, pore opening, and performance optimization. The temperature is 80-95℃, with a moderate dissolution rate that forms uniform micropores while preventing softening and deformation of the leather's resin coating. A fiber opening time of 40-60 minutes yields a weight reduction of 8-15% and maintains a complete microporous structure; too short a time (less than 30 minutes) results in a high residual rate of water-soluble components, minimal weight reduction, and limited improvement in breathability; too long a time (more than 90 minutes) excessively erodes the fiber bonding points, leading to decreased tear strength.

[0030] In S3, the drying process uses a 7-stage oven gradient heating system with temperatures set at 80-90℃, 88-98℃, 100-110℃, 110-120℃, 125-130℃, 130-135℃ and 145-150℃ respectively; the machine speed is 4.5-6.5m / min.

[0031] In S4, the second waterborne aromatic polyurethane resin used in the fabric layer has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength of ≥10MPa, and an elongation of ≥300%; the second waterborne aromatic polyurethane resin is purchased from KTT728F of Hefei Ketian Waterborne Technology Co., Ltd.

[0032] The fabric layer preparation process is as follows: an appropriate amount of second water-based aromatic polyurethane resin and polyurethane associative thickener are added to a reaction vessel and stirred. The stirring speed is 2000-4500 r / min, the time is 30-40 min, and the viscosity is controlled at 3000-5000 cps.

[0033] In step S4, the activation temperature of the thermally activated waterborne polyurethane resin is 50-55℃, the solid content is 50±2%, the pH value is 6.0~8.0, and the viscosity is 100-300cps. The thermally activated waterborne polyurethane resin is purchased from Hefei Huayue New Material Technology Co., Ltd. as PU-7# waterborne polyurethane resin.

[0034] The preparation process of the base layer is as follows: an appropriate amount of thermally activated waterborne polyurethane resin and polyurethane associative thickener are added to the reaction vessel and stirred. The stirring speed is 3000-5500 r / min, the time is 30-40 min, and the viscosity is controlled at 4000-6000 cps.

[0035] In this invention, the solid content of the polyurethane associative thickener is 40±2%, and the associative polyurethane thickener HEUR-01 purchased from Hefei Anke Fine Chemical Co., Ltd. is used to adjust viscosity and leveling properties.

[0036] In S4, the coating thickness of the fabric layer is 10-18 filaments, the drying temperature is 110-130℃, and the drying time is 2-3 minutes.

[0037] In step S4, the thickness of the base coat is 20-25 mils, the drying temperature is 80-100℃, and the drying time is 5-10 minutes. Too low a temperature will prevent the thermally activated waterborne polyurethane resin from crosslinking, while too high a temperature will cause the thermally activated waterborne polyurethane to dry before complete crosslinking. In S4, after the base layer is compounded with water-soluble polyurethane base, it is dried at 120-140℃ for 5-8 minutes to obtain the high-strength, fully environmentally friendly water-soluble leather.

[0038] The beneficial technical effects of the preparation process of the high-strength, fully environmentally friendly, water-soluble, and water-based shoe leather of the present invention are further illustrated below through several examples and comparative examples. Example 1

[0039] This example provides a preparation process for high-strength, fully environmentally friendly, water-soluble, water-based shoe leather, including the following steps: S1: Wet Impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion is prepared from 100 parts of a first waterborne aromatic polyurethane resin, 0.8 parts of a polyurethane associative thickener, and 1.2 parts of an anionic penetrant. The anionic penetrant is sodium diisooctyl succinate sulfonate. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0040] S2: Acid coagulation: The impregnated base fabric is coagulated at 30°C for 20 minutes using a 16% citric acid solution.

[0041] S3: The base fabric after acid coagulation is subjected to hot water fiber opening, drying, oiling, and kneading to obtain water-soluble waterborne polyurethane base.

[0042] S4: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second waterborne aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a heat-activated waterborne polyurethane resin and 1 part of a polyurethane associative thickener. The base layer is then combined with a water-soluble waterborne polyurethane base to obtain the high-strength, fully environmentally friendly water-soluble waterborne shoe leather. The second waterborne aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The heat-activated waterborne polyurethane resin has an activation temperature of 50-55℃, a solid content of 50±2%, a pH value of 6.0~8.0, and a viscosity of 100-300cps. The polyurethane associative thickener has a solid content of 40±2%. The coating thickness of the fabric layer is 10-18 mils, the drying temperature is 110-130℃, and the drying time is 2-3 minutes. The coating thickness of the base layer is 20-25 mils, the drying temperature is 100℃, and the drying time is 10 minutes. After the base layer is compounded with water-soluble polyurethane base, it is dried at 130℃ for 8 minutes to obtain the high-strength, fully environmentally friendly water-soluble leather. Example 2

[0043] This example provides a preparation process for high-strength, fully environmentally friendly, water-soluble, water-based shoe leather, including the following steps: S1: Wet Impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion is prepared from 100 parts of a first waterborne aromatic polyurethane resin, 0.3 parts of a polyurethane associative thickener, and 1 part of an anionic penetrant. The anionic penetrant is sodium diisooctyl succinate sulfonate. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0044] S2: Acid coagulation: The impregnated base fabric is coagulated at 30°C for 20 minutes using a 16% citric acid solution.

[0045] S3: The base fabric after acid coagulation is subjected to hot water fiber opening, drying, oiling, and kneading to obtain water-soluble waterborne polyurethane base.

[0046] S4: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second waterborne aromatic polyurethane resin and 0.3 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a heat-activated waterborne polyurethane resin and 0.5 parts of a polyurethane associative thickener. The base layer is then combined with a water-soluble waterborne polyurethane base to obtain the high-strength, fully environmentally friendly water-soluble waterborne shoe leather. The second waterborne aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The heat-activated waterborne polyurethane resin has an activation temperature of 50-55℃, a solid content of 50±2%, a pH value of 6.0~8.0, and a viscosity of 100-300cps. The polyurethane associative thickener has a solid content of 40±2%. The coating thickness of the fabric layer is 10-18 mils, the drying temperature is 110-130℃, and the drying time is 2-3 minutes. The coating thickness of the base layer is 20-25 mils, the drying temperature is 100℃, and the drying time is 10 minutes. After the base layer is compounded with water-soluble polyurethane base, it is dried at 130℃ for 8 minutes to obtain the high-strength, fully environmentally friendly water-soluble leather. Example 3

[0047] This example provides a preparation process for high-strength, fully environmentally friendly, water-soluble, water-based shoe leather, including the following steps: S1: Wet Impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion is prepared from 100 parts of a first waterborne aromatic polyurethane resin, 1.2 parts of a polyurethane associative thickener, and 1.5 parts of an anionic penetrant. The anionic penetrant is sodium diisooctyl succinate sulfonate. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0048] S2: Acid coagulation: The impregnated base fabric is coagulated at 30°C for 20 minutes using a 16% citric acid solution.

[0049] S3: The base fabric after acid coagulation is subjected to hot water fiber opening, drying, oiling, and kneading to obtain water-soluble waterborne polyurethane base.

[0050] S4: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second waterborne aromatic polyurethane resin and 1.2 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a heat-activated waterborne polyurethane resin and 1.5 parts of a polyurethane associative thickener. The base layer is then combined with a water-soluble waterborne polyurethane base to obtain the high-strength, fully environmentally friendly water-soluble waterborne shoe leather. The second waterborne aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The heat-activated waterborne polyurethane resin has an activation temperature of 50-55℃, a solid content of 50±2%, a pH value of 6.0~8.0, and a viscosity of 100-300cps. The polyurethane associative thickener has a solid content of 40±2%. The coating thickness of the fabric layer is 10-18 mils, the drying temperature is 110-130℃, and the drying time is 2-3 minutes. The coating thickness of the base layer is 20-25 mils, the drying temperature is 100℃, and the drying time is 10 minutes. After the base layer is compounded with water-soluble polyurethane base, it is dried at 130℃ for 8 minutes to obtain the high-strength, fully environmentally friendly water-soluble leather.

[0051] Comparative Example 1 This example provides a manufacturing process for shoe leather, including the following steps: S1: Wet impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion consists of 100 parts of a first waterborne aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0052] S2: The impregnated base fabric is subjected to hot water fiber opening, drying, oiling, and rubbing to obtain the base fabric.

[0053] S3: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second water-based aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a second water-based aromatic polyurethane resin and 1 part of a polyurethane associative thickener. The base layer is then laminated with a base layer to obtain the shoe leather. The second water-based aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The top layer has a coating thickness of 10~18 mils, a drying temperature of 110~130℃, and a drying time of 2~3 min. The base layer has a coating thickness of 20-25 mils, a drying temperature of 100℃, and a drying time of 10 min. After the base layer is combined with the base material, it is dried at 130°C for 8 minutes to obtain the shoe leather.

[0054] Comparative Example 2 This example provides a manufacturing process for shoe leather, including the following steps: S1: Wet Impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion is prepared from 100 parts of a first waterborne aromatic polyurethane resin, 0.8 parts of a polyurethane associative thickener, and 1.2 parts of an anionic penetrant. The anionic penetrant is sodium diisooctyl succinate sulfonate. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0055] S2: The impregnated base fabric is subjected to hot water fiber opening, drying, oiling, and rubbing to obtain the base fabric.

[0056] S3: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second water-based aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a second water-based aromatic polyurethane resin and 1 part of a polyurethane associative thickener. The base layer is then laminated with a base layer to obtain the shoe leather. The second water-based aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The top layer has a coating thickness of 10~18 mils, a drying temperature of 110~130℃, and a drying time of 2~3 min. The base layer has a coating thickness of 20-25 mils, a drying temperature of 100℃, and a drying time of 10 min. After the base layer is combined with the base material, it is dried at 130°C for 8 minutes to obtain the shoe leather.

[0057] Comparative Example 3 This example provides a manufacturing process for shoe leather, including the following steps: S1: Wet Impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion consists of 100 parts of a first waterborne aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0058] S2: Acid coagulation: The impregnated base fabric is coagulated at 30°C for 20 minutes using a 16% citric acid solution.

[0059] S3: After acid coagulation, the base fabric is opened with hot water, dried, oiled, and kneaded to obtain the base fabric.

[0060] S4: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second water-based aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a second water-based aromatic polyurethane resin and 1 part of a polyurethane associative thickener. The base layer is then laminated with a base layer to obtain the shoe leather. The second water-based aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The top layer is coated to a thickness of 10~18 mils, dried at 110~130℃ for 2~3 minutes. The base layer is coated to a thickness of 20-25 mils, dried at 100℃ for 10 minutes. After the base layer is combined with the base material, it is dried at 130°C for 8 minutes to obtain the shoe leather.

[0061] Comparative Example 4 This example provides a manufacturing process for shoe leather, including the following steps: S1: Wet Impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion consists of 100 parts of a first waterborne aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0062] S2: The impregnated base fabric is subjected to hot water fiber opening, drying, oiling, and rubbing to obtain the base fabric.

[0063] S3: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second waterborne aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a heat-activated waterborne polyurethane resin and 1 part of a polyurethane associative thickener. The base layer is then laminated with a base layer to obtain the shoe leather. The second waterborne aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The heat-activated waterborne polyurethane resin has an activation temperature of 50-55℃, a solid content of 50±2%, a pH value of 6.0~8.0, and a viscosity of 100-300cps. The polyurethane associative thickener has a solid content of 40±2%. The coating thickness of the fabric layer is 10-18 mils, the drying temperature is 110-130℃, and the drying time is 2-3 minutes. The coating thickness of the base layer is 20-25 mils, the drying temperature is 100℃, and the drying time is 10 minutes. After the base layer is laminated with the base material, it is dried at 130℃ for 8 minutes to obtain the shoe leather.

[0064] Comparative Example 5 This example provides a manufacturing process for shoe leather, including the following steps: S1: Wet Impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion is prepared from 100 parts of a first waterborne aromatic polyurethane resin, 0.8 parts of a polyurethane associative thickener, and 1.2 parts of an anionic penetrant. The anionic penetrant is sodium diisooctyl succinate sulfonate. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0065] S2: The impregnated base fabric is subjected to hot water fiber opening, drying, oiling, and rubbing to obtain the base fabric.

[0066] S3: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second waterborne aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a heat-activated waterborne polyurethane resin and 1 part of a polyurethane associative thickener. The base layer is then laminated with a base layer to obtain the shoe leather. The second waterborne aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The heat-activated waterborne polyurethane resin has an activation temperature of 50-55℃, a solid content of 50±2%, a pH value of 6.0~8.0, and a viscosity of 100-300cps. The polyurethane associative thickener has a solid content of 40±2%. The coating thickness of the fabric layer is 10-18 mils, the drying temperature is 110-130℃, and the drying time is 2-3 minutes. The coating thickness of the base layer is 20-25 mils, the drying temperature is 100℃, and the drying time is 10 minutes. After the base layer is laminated with the base material, it is dried at 130℃ for 8 minutes to obtain the shoe leather.

[0067] Comparative Example 6 This example provides a manufacturing process for shoe leather, including the following steps: S1: Wet Impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion is prepared from 100 parts of a first waterborne aromatic polyurethane resin, 0.8 parts of a polyurethane associative thickener, and 1.2 parts of an anionic penetrant. The anionic penetrant is sodium diisooctyl succinate sulfonate. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0068] S2: Acid coagulation: The impregnated base fabric is coagulated at 30°C for 20 minutes using a 16% citric acid solution.

[0069] S3: The base fabric after acid coagulation is subjected to hot water fiber opening, drying, oiling, and kneading to obtain water-soluble waterborne polyurethane base.

[0070] S4: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second water-based aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a second water-based aromatic polyurethane resin and 1 part of a polyurethane associative thickener. The base layer is then combined with a water-soluble polyurethane base to obtain the shoe leather. The second water-based aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The top layer has a coating thickness of 10~18 mils, a drying temperature of 110~130℃, and a drying time of 2~3 min. The base layer has a coating thickness of 20-25 mils, a drying temperature of 100℃, and a drying time of 10 min. The base layer is compounded with water-soluble polyurethane base and then dried at 130°C for 8 minutes to obtain the shoe leather.

[0071] Comparative Example 7 This example provides a manufacturing process for shoe leather, including the following steps: S1: Wet impregnation: A water-soluble waterborne nonwoven fabric (70% nylon and 30% PVA) is wet impregnated with a waterborne bio-based polyurethane working emulsion to obtain an impregnated base fabric. The waterborne bio-based polyurethane working emulsion consists of 100 parts of a first waterborne aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The first waterborne aromatic polyurethane resin has a solid content of 41±1%, a pH value of 6.0~8.0, a viscosity ≤1000cps, a modulus of 1.2MPa, a tensile strength ≥5MPa, and an elongation ≥800%.

[0072] S2: Acid coagulation: The impregnated base fabric is coagulated at 30°C for 20 minutes using a 16% citric acid solution.

[0073] S3: After acid coagulation, the base fabric is opened with hot water, dried, oiled, and kneaded to obtain the base fabric.

[0074] S4: Dry Lamination: A top layer and a base layer are sequentially coated onto release paper. The top layer is made of 100 parts of a second waterborne aromatic polyurethane resin and 0.8 parts of a polyurethane associative thickener. The base layer is made of 100 parts of a heat-activated waterborne polyurethane resin and 1 part of a polyurethane associative thickener. The base layer is then laminated with a base layer to obtain the shoe leather. The second waterborne aromatic polyurethane resin has a solid content of 30±1%, a pH value of 6.0~8.0, a viscosity of 3500±1000cps, a modulus of 3.0~4.5MPa, a tensile strength ≥10MPa, and an elongation ≥300%. The heat-activated waterborne polyurethane resin has an activation temperature of 50-55℃, a solid content of 50±2%, a pH value of 6.0~8.0, and a viscosity of 100-300cps. The polyurethane associative thickener has a solid content of 40±2%. The coating thickness of the fabric layer is 10-18 mils, the drying temperature is 110-130℃, and the drying time is 2-3 minutes. The coating thickness of the base layer is 20-25 mils, the drying temperature is 100℃, and the drying time is 10 minutes. After the base layer is laminated with the base material, it is dried at 130℃ for 8 minutes to obtain the shoe leather.

[0075]

[0076]

[0077] The performance test data in Tables 1 and 2 clearly show that: 1. The present invention, through the synergistic technical solution of adding anionic penetrant to waterborne polyurethane working emulsion, acid coagulation, and adding thermally activated waterborne polyurethane resin to the base layer, produces shoe leather with all mechanical performance indicators (bursting, tensile, tearing, peeling) reaching the highest value, and comprehensively outperforming any single or paired comparative example, fully meeting and far exceeding the standard requirements.

[0078] 2. Comparative Example 1 is the existing technology. Its mechanical properties (such as bursting strength 180N and peel strength 42 / 45N) are at the lowest level. Moreover, its key stability indicators such as hydrolysis resistance, normal / low temperature flexural resistance, and abrasion resistance are all unqualified. Its comprehensive performance cannot meet the application requirements of high-end shoe leather.

[0079] 3. Comparative Example 2 only added anionic penetrant. The penetrant improved the processing uniformity, resulting in some mechanical properties such as tensile strength and elongation (e.g., the longitudinal tensile strength increased to 485N), and it barely passed the room temperature flexural endurance test. However, due to the lack of a dense cross-linked structure resulting from acid coagulation, its tear strength, hydrolysis resistance, and -10℃ flexural endurance were still unqualified, indicating that using anionic penetrant alone cannot solve the structural stability problem of water-based leather under harsh environments.

[0080] 4. Comparative Example 3, using only acid coagulation, significantly improved the bursting strength (220N) and structural density (hydrolysis resistance and abrasion resistance were satisfactory). However, due to the lack of uniformity guaranteed by the penetrant and the efficient adhesion provided by the heat-activated resin, its conventional peel strength (55 / 61N) and room temperature folding endurance were still unsatisfactory, indicating that although acid coagulation strengthened the base, it failed to solve the interfacial bonding problem of the laminate.

[0081] 5. Comparative Example 4 uses only heat-activated polyurethane resin: The heat-activated polyurethane resin greatly improves the adhesive strength of the laminate (peel strength 82 / 84N), thus making it pass the room temperature folding resistance test. However, because the base itself has not undergone acid coagulation strengthening and the processing uniformity is insufficient, its bursting strength is only 245N and its low temperature folding resistance still has shortcomings.

[0082] 6. Comparative Example 5, with the addition of anionic penetrant and thermally activated polyurethane resin, exhibited good processing uniformity and interfacial adhesion, resulting in excellent tensile strength, elongation, and room-temperature flexural endurance. However, the lack of acid coagulation led to unsatisfactory hydrolysis resistance and low-temperature flexural endurance, highlighting the irreplaceable role of base structure densification in environmental resistance.

[0083] 7. Comparative Example 6, with the addition of an anionic penetrant and acid coagulation, produced a baseplate with excellent uniformity and a bursting strength of 228 N, meeting the standards for hydrolysis and abrasion resistance. However, due to the use of conventional resin during lamination, the interfacial adhesive strength (peel strength 66 / 65 N) became a bottleneck. Although its conventional peel strength was improved compared to Comparative Example 3, it was still far lower than that of the example, and the potential of the reinforced baseplate was not fully realized.

[0084] 8. Comparative Example 7 was acid-cured and heat-activated polyurethane resin was used. This combination performed well in both base reinforcement and interfacial adhesion, achieving the required peel strength (82 / 77N) and low-temperature folding resistance. However, the lack of penetrant resulted in insufficient processing uniformity, and the weft data of its tensile and tear strength (345N, 59N) showed significant fluctuations and shortcomings. Although the Taber abrasion resistance was qualified, the performance margin was insufficient, reflecting risks to production stability and product consistency.

[0085] 9. Therefore, the present invention integrates three technical features: the addition of anionic penetrants to the waterborne bio-based polyurethane working emulsion, acid coagulation, and the addition of thermally activated waterborne polyurethane resin to the base layer. The anionic penetrants create a uniform reaction environment for acid coagulation, resulting in a more complete cross-linking structure. The reinforced base layer is combined with the strong interfacial adhesion provided by the thermally activated waterborne polyurethane resin, successfully producing a fully environmentally friendly waterborne shoe leather that simultaneously possesses high strength, high adhesion, excellent folding resistance (especially in low-temperature environments), and outstanding environmental stability.

[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for preparing high strength, fully environmentally friendly water-based waterborne shoe leather, characterized by: It comprises the following steps: S1: wet impregnation: using water-based polyurethane working emulsion for water-soluble water-based non-woven fabric wet impregnation, getting impregnated base cloth, the water-based polyurethane working emulsion is prepared by 100 parts of the first water-based aromatic polyurethane resin, 0.3-1.2 parts of polyurethane associated thickener, 1-1.5 parts of anionic penetrant; S2: acid coagulation: using citric acid solution for acid coagulation of impregnated base cloth; S3: the base cloth after acid coagulation is heated water opening, drying, oiling, rubbing, getting water-soluble water-based polyurethane belt; S4: dry surface: on release paper, the fabric layer and the primer layer are coated in turn, the fabric layer is made of 100 parts of the second water-based aromatic polyurethane resin and 0.3-1.2 parts of polyurethane associated thickener, the primer layer is made of 100 parts of the hot activated water-based polyurethane resin and 0.5-1.5 parts of polyurethane associated thickener; the primer layer is compounded with water-soluble water-based polyurethane belt to get the high-strength full environmental protection water-soluble water-based shoe leather.

2. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: In S1, the water-soluble nonwoven fabric comprises 65-75% nylon and 25-35% pva; the gram weight is 500-700 g / m 2 , the width is ≥ 148 cm.

3. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: In S1, the anionic penetrant is sodium diisooctyl sulfosuccinate.

4. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: The solid content of the first water-based aromatic polyurethane resin is 41±1%, the pH value is 6.0-8.0, the viscosity is ≤1000cps, the modulus is 1.2MPa, the breaking strength is ≥5MPa, and the elongation is ≥800%.

5. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: The preparation process of the water-based polyurethane working emulsion is as follows: a certain amount of the first water-based aromatic polyurethane resin, polyurethane associated thickener and anionic penetrant are weighed and added to the reaction kettle, and stirred at a speed of 2300-4300r / min for 40-60min, and the viscosity is controlled at 2000-4000cps to prepare the water-based polyurethane working emulsion.

6. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: In S2, the impregnated base cloth uses 13-20% citric acid solution, and coagulates at 25-30℃ for 15-25min.

7. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: In S4, the activation temperature of the hot activated water-based polyurethane resin is 50-55℃, the solid content is 50±2%, the pH value is 6.0-8.0, and the viscosity is 100-300cps.

8. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: The solid content of the second water-based aromatic polyurethane resin is 30±1%, the pH value is 6.0-8.0, the viscosity is 3500±1000cps, the modulus is 3.0-4.5MPa, the breaking strength is ≥10MPa, and the elongation is ≥300%.

9. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: The solid content of the polyurethane associated thickener is 40±2%.

10. The process for preparing high strength, fully environmentally friendly water soluble water-based shoe leather according to claim 1, characterized in that: The coating thickness of the fabric layer is 10-18 silk, the drying temperature is 110-130℃, and the drying time is 2-3min, the coating thickness of the primer layer is 20-25 silk, the drying temperature is 80-100℃, and the drying time is 5-10min; after the primer layer is compounded with the water-soluble water-based polyurethane belt, it is dried at 120-140℃ for 5-8min to get the high-strength full environmental protection water-soluble water-based shoe leather.

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