Aqueous polyurethane resin for shoe lining and preparation method thereof

Abstract

The present invention discloses a water-based polyurethane resin for shoe lining leather and a preparation method thereof. The raw materials include the following components by mass fraction: 35% to 50% polyether polyol, 0.1% to 1% small molecule diol, 1% to 2% carboxylic acid type hydrophilic chain extender, 8% to 12% isocyanate, 0.001% to 0.015% catalyst, 0.1% to 0.2% cross-linking agent, 0.1% to 2% diamine chain extender, 1% to 1.5% neutralizing agent, and 60% to 70% water; the polyether polyol includes a mixture of a polyether diol with a number average molecular weight of 800 to 1200 and a polyether diol with a number average molecular weight of 1800 to 2200 in a mass ratio of (1 to 4):1; the isocyanate is toluene-2,4-diisocyanate or / and toluene-2,6-diisocyanate. The resin of the present invention is not easy to crack when dried at high temperature, has a soft and plump feel, good hygroscopicity and moisture discharge, high filler content, and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane resin for synthetic leather, and particularly relates to a water-based polyurethane resin for shoe lining leather and a preparation method thereof. Background Art

[0002] As we all know, natural leather resources are limited, the price is high, and it cannot meet the growing market demand. The solvent-based polyurethane resins used in the production of traditional polyurethane shoe linings contain large amounts of toxic and hazardous organic solvents, such as DMF and MEK, which pollute the environment. Residual organic solvents can also harm the user's body. Water-based breathable shoe linings, made with zero-solvent water-based polyurethane, fundamentally improve the environmental pollution and human harm caused by organic solvents. Furthermore, water-based polyurethane synthetic leather offers advantages such as relatively low price, excellent processing performance, and environmental friendliness. Its overall performance rivals that of genuine leather, and even offers a superior feel to natural leather, resulting in a growing market share.

[0003] However, the sharp rise in the cost of chemical raw materials has seriously hindered the application and development of water-based, environmentally friendly polyurethane resins. Shoe lining leather, which has lower physical property requirements, has more stringent cost requirements. Currently, water-based polyurethane resins for shoe lining leather on the market are generally synthesized from aliphatic isocyanates, which are relatively expensive and have extremely low powder absorption rates. The amount of filler added generally does not exceed 50% of the water-based polyurethane resin used. For example, patent document CN109537298A discloses a water-absorbent and breathable shoe lining leather and its preparation method. The foaming layer of the shoe lining leather comprises the following raw materials in parts by weight: 95-105 parts of water-based foaming polyurethane resin, 10-30 parts of kaolin, 1-3 parts of water-based foaming agent, 1-3 parts of water-based foam stabilizer, 1-3 parts of water-based thickener, and 1 part of water-based dispersant. However, the water-based foamed polyurethane resin in this document has good film-forming properties, while the maximum amount of filler added is only 30% of the water-based foamed polyurethane resin, and the powder absorption rate is low, which will lead to a low porosity in the foaming layer, and thus poor moisture and air permeability of the shoe lining leather, and high cost.

[0004] Patent document CN103772644A discloses a modified waterborne polyurethane resin, the raw materials of which include: 10-20% isophorone diisocyanate, 10-20% polyester polyol, 5-10% dimethylol propionic acid, 5-10% triethylamine, 5-10% diethylene glycol, 40-60% deionized water, and 1-3% diethylenetriamine. The synthesis method comprises: (1) adding isophorone diisocyanate into a blender, adding polyether polyol and dimethylol propionic acid dropwise, and reacting at about 60-80°C for about 3-5 hours; (2) adding diethylene glycol for chain extension reaction for 1-5 hours and cooling to room temperature; (3) adding deionized water containing triethylamine, emulsifying in a high-speed disperser, and adding diethylenetriamine for modification to obtain a light yellow, translucent waterborne polyurethane dispersion. The present invention adopts a stepwise polymerization reaction and a small molecule polyol for modification, thereby improving the performance of waterborne polyurethane and making it more widely applicable, and also reducing costs. This document adopts a step-by-step polymerization method, using isophorone diisocyanate with two isocyanate groups with similar reactivity as the hard segment. The molecular chain segments obtained by polymerization have a regular structure and uniform molecular weight. In addition, the amount of dimethylolpropionic acid used in the system is 5%-10%, and the prepared emulsion has a small particle size and a narrow particle size distribution. These result in a low amount of filler that can be added to the resin. If used to prepare shoe lining leather, the air permeability and moisture permeability will be poor, and the feel will be very stiff.

[0005] Patent document CN114108334A discloses a high-stripping, butanone-resistant waterborne polyurethane resin, its preparation method, and applications. The resin comprises the following components: a polyol component, an isocyanate, a hydrophilic carboxylic acid chain extender, an alcohol chain extender, an amine chain extender, a crosslinker, a catalyst, a neutralizer, and water. The polyol component comprises polytetramethylene glycol and polycarbonate diol; the isocyanate comprises dicyclohexylmethane diisocyanate; and the amine chain extender comprises an alcoholamine chain extender. This document uses dicyclohexylmethane diisocyanate as the hard segment. Dicyclohexylmethane diisocyanate has a symmetrical structure and strong crystallinity. The resulting resin exhibits strong crystallinity, small emulsion particle size, and a narrow particle size distribution. During the preparation and drying process, the resulting film forms a smooth, dense surface. However, when used to make shoe lining leather, the resin has a stiff feel and poor air and moisture permeability. Summary of the Invention

[0006] The present invention aims to provide a water-based polyurethane resin for shoe lining leather and a preparation method thereof, which can self-foam and has good stability, meets the physical property requirements of shoe lining leather, and can greatly increase the addition ratio of inorganic fillers in the foaming layer resin, thereby solving the problems of low powder absorption rate and high cost of the existing water-based polyurethane resin for the foaming layer of shoe lining leather.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The invention provides a water-based polyurethane resin for shoe lining leather, characterized in that its raw materials include the following components in mass fractions: 35% to 50% of polyether polyol, 0.1% to 1% of small molecule diol, 1% to 2% of carboxylic acid type hydrophilic chain extender, 8% to 12% of isocyanate, 0.001% to 0.015% of catalyst, 0.1% to 0.2% of cross-linking agent, 0.1% to 2% of diamine chain extender, 1% to 1.5% of neutralizer, and 60% to 70% of water;

[0009] The polyether polyol comprises a mixture of a polyether diol with a number average molecular weight of 800 to 1200 and a polyether diol with a number average molecular weight of 1800 to 2200 in a mass ratio of (1 to 4):1; the polyether diol is at least one of polytetramethylene glycol and polycaprolactone diol; the small molecule diol is at least one of propylene glycol, ethylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; the isocyanate is toluene-2,4-diisocyanate and / or toluene-2,6-diisocyanate;

[0010] The total molar ratio of the isocyanate to the polyether polyol, the carboxylic acid type hydrophilic chain extender and the small molecule diol chain extender is 1:(0.85-0.95);

[0011] The carboxylic acid type hydrophilic chain extender is at least one of 2,2'-dimethylol propionic acid (DMPA) and 2,2'-dimethylol butyric acid; the cross-linking agent is trimethylol propane and / or diethylenetriamine, and the diamine chain extender is selected from ethylenediamine and / or isophoronediamine;

[0012] The neutralizing agent is triethylamine; the molar ratio of the neutralizing agent to the carboxylic acid type hydrophilic chain extender is (0.95-1.05):1; and the catalyst is an organic bismuth catalyst.

[0013] The water-based polyurethane resin for shoe lining leather of the present invention has low surface tension and can effectively stabilize bubbles to prevent them from bursting. After film formation, the film is tested in accordance with GB / T19250-2013, and the elongation at break of the film is ≥1000%, the modulus is ≤1.5 MPa, and the strength is ≥5 MPa.

[0014] The method for preparing the aqueous polyurethane resin for shoe lining leather of the present invention is characterized by comprising the following steps:

[0015] (1) Under the action of the catalyst, the polyether polyol, the carboxylic acid type hydrophilic chain extender, the small molecule diol and the isocyanate are subjected to a one-step prepolymerization reaction at 75-85° C. until the NCO value test is qualified to obtain an NCO-terminated prepolymer;

[0016] (2) adding acetone to the prepolymer and stirring uniformly; controlling the system temperature to 35-45° C., adding the neutralizing agent and stirring to react to form a salt; then cooling to 15-25° C., adding water and stirring to emulsify to obtain an unextended chain emulsion;

[0017] (3) adding the crosslinking agent and the diamine chain extender to the unextended emulsion, stirring and reacting for 20 to 80 minutes; vacuuming and removing acetone to obtain the water-based polyurethane resin for shoe lining leather;

[0018] The NCO value of the prepolymerization reaction in step (1) is 1.3% to 1.7% of the total mass fraction, preferably 1.5%.

[0019] The water-based polyurethane resin for shoe lining leather of the present invention is used to prepare a resin slurry, which is coated on a synthetic leather base fabric as a foaming layer to prepare shoe lining leather. The resin slurry generally comprises: 100 parts of the water-based polyurethane resin for shoe lining leather, 50 to 150 parts of a filler, 0.1 to 1 part of a thickener, and 0.5 to 1.5 parts of a color paste.

[0020] The viscosity of the resin slurry is 25000-30000 CPS;

[0021] The filler includes at least one of heavy calcium carbonate, light calcium carbonate, kaolin and wood powder.

[0022] According to an embodiment of the present invention, the shoe lining leather is tested with reference to the standard GB / T2791-1995, and the peel strength is 20-25N / 3cm; it is tested with reference to the standard GB / T3903.1-2008, and is flexed more than 30,000 times at room temperature (20-40°C) and more than 50,000 times at low temperature (-20--5°C).

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The present invention mainly uses low-molecular-weight polyether polyol and a certain amount of high-molecular-weight polyether polyol. Since the crystallinity and reactivity of polyols with a molecular weight of 1000 and 2000 are different (the molecular chain of 1000 molecular weight polyol is short, the reactivity is high, and the crystallinity is worse than that of 2000 molecular weight polyol), the molecular chain segment growth is more random in the prepolymerization stage. At the same time, TDI is used as isocyanate, and the reactivity of its two isocyanate groups at lower temperatures is very different. Therefore, the molecular weight distribution of the obtained prepolymer is very wide, and the crystallinity of the prepared water-based polyurethane deteriorates during film formation, resulting in slower film formation. The prepared water-based polyurethane resin emulsion has a larger particle size and a wider molecular weight distribution. The base made of these emulsions has uneven latex particles, large gaps between latex particles, and can form more, finer, and more uniform bubbles during the drying process. When adding fillers, the inorganic fillers will be more dispersed between the latex particles, which greatly improves the powder absorption rate of the water-based polyurethane resin. When the aqueous polyurethane resin of the present invention is used to prepare shoe lining leather, filler can be gradually added to 150 parts of 100 parts of the aqueous polyurethane resin, while maintaining the soft and plump feel of the final prepared shoe lining leather. This not only significantly reduces the cost of downstream customers, but also the high filler content can increase the air permeability and moisture permeability of the shoe lining leather.

[0025] Since polyols of different molecular weights are selected in the waterborne polyurethane of the present invention and the waterborne polyurethane resin is synthesized by a one-step method, the hard segments and soft segments of the molecular chain are unevenly distributed, the hydrophilicity of the soft and hard segments differs greatly, and the molecular chains play an emulsifying role. During mechanical stirring or the injection of air, the molecular chains can better wrap around bubbles without breaking them. Moreover, a high proportion of fillers makes it easier to introduce bubbles. The waterborne polyurethane resin of the present invention can effectively stabilize these bubbles and prevent them from breaking, thereby achieving self-foaming with good stability.

[0026] The water-based polyurethane resin for shoe lining leather of the present invention is not easy to crack during high-temperature drying, has a soft and plump hand feel, good moisture absorption and moisture discharge properties, is high in fillers, and is low in cost, thereby solving the market demand for low-property, low-cost yellowing water-based polyurethane resins. DETAILED DESCRIPTION

[0027] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the invention.In addition, should be understood that after reading content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope of the application's appended claims limitation.

[0028] Examples 1 to 4

[0029] The raw material formulas of the water-based polyurethane resin for shoe lining leather of Examples 1 to 4 are shown in Table 1, wherein the isocyanate is toluene-2,4-diisocyanate TDI, the polyether polyols are PTMG2000, PTMG1000 and PPG1000, the small molecule alcohol chain extender is ethylene glycol, the amine cross-linking agent is diethylenetriamine, and the diamine chain extender is ethylenediamine.

[0030] The preparation method of the aqueous polyurethane resin for shoe lining leather comprises the following steps:

[0031] (1) Polyether polyols PTMG2000, PTMG1000, and PPG1000, a carboxylic acid-type hydrophilic chain extender DMPA, and ethylene glycol were added to a reactor and stirred uniformly. TDI was then added, and a one-step prepolymerization reaction was carried out at 80° C. in the presence of an organic bismuth catalyst for 4 hours. A sample was taken from the sampling port, and the residual isocyanate content was titrated using a di-n-butylamine method. The prepolymer was obtained by passing the theoretical NCO value test (1.5% of the total mass fraction).

[0032] (2) adding acetone to the prepolymer to dilute the prepolymer and stirring for 30 minutes to obtain a homogeneous prepolymer solution; controlling the temperature to maintain at 40°C, adding a neutralizing agent triethylamine, and stirring for 15 minutes to react and form a salt; then cooling the reactor to 20°C, adding water and stirring and emulsifying to obtain an unextended chain emulsion;

[0033] (3) After stirring for 10 minutes, a mixed solution of diethylenetriamine and ethylenediamine was added to the unextended emulsion, and the stirring reaction was continued for 30 minutes; then the temperature was raised to 45°C, and the acetone was removed by vacuuming to -0.08 MPa. After no acetone flowed out, the temperature was lowered to below 30°C and the material was discharged to obtain a water-based polyurethane resin for shoe lining leather.

[0034] Table 1 Raw materials of waterborne polyurethane resins of Examples 1 to 6 and Comparative Examples 1 to 4, parts by weight

[0035]

[0036] Example 5

[0037] (1) Polyether polyols PTMG2000, PTMG1000, and PPG1000, a carboxylic acid-type hydrophilic chain extender DMPA, and ethylene glycol were added to a reactor and stirred uniformly. TDI was then added, and a one-step prepolymerization reaction was carried out at 80° C. in the presence of an organic bismuth catalyst for 4 hours. A sample was taken from the sampling port, and the residual isocyanate content was titrated using a di-n-butylamine method. The prepolymer was obtained by passing the theoretical NCO value test (1.5% of the total mass fraction).

[0038] (2) adding acetone to the prepolymer to dilute the prepolymer and stirring for 30 minutes to obtain a homogeneous prepolymer solution; controlling the temperature to maintain at 35°C, adding a neutralizing agent triethylamine, and stirring for 15 minutes to react and form a salt; then cooling the reactor to 25°C, adding water and stirring and emulsifying to obtain an unextended chain emulsion;

[0039] (3) After stirring for 10 minutes, a mixed solution of diethylenetriamine and ethylenediamine was added to the unextended emulsion, and the stirring reaction was continued for 30 minutes; then the temperature was raised to 45°C, and the acetone was removed by vacuuming to -0.08 MPa. After no acetone flowed out, the temperature was lowered to below 30°C and the material was discharged to obtain a water-based polyurethane resin for shoe lining leather.

[0040] Example 6

[0041] (1) Adding polyether polyols PTMG2000, PTMG1000, and PPG1000, a carboxylic acid-type hydrophilic chain extender DMPA, and ethylene glycol into a reactor and stirring them uniformly, then adding TDI, and carrying out a one-step prepolymerization reaction at 75° C. in the presence of an organic bismuth catalyst for 6 hours; taking a sample from a sampling port, and titrating the residual isocyanate content using a di-n-butylamine method, and obtaining a prepolymer by reaching a qualified theoretical NCO value test (accounting for 1.5% of the total mass fraction);

[0042] (2) adding acetone to the prepolymer to dilute the prepolymer and stirring for 30 minutes to obtain a homogeneous prepolymer solution; controlling the temperature to maintain at 40°C, adding a neutralizing agent triethylamine, and stirring for 15 minutes to react and form a salt; then cooling the reactor to 20°C, adding water and stirring and emulsifying to obtain an unextended chain emulsion;

[0043] (3) After stirring for 10 minutes, a mixed solution of diethylenetriamine and ethylenediamine was added to the unextended emulsion, and the stirring reaction was continued for 30 minutes; then the temperature was raised to 45°C, and the acetone was removed by vacuuming to -0.08 MPa. After no acetone flowed out, the temperature was lowered to below 30°C and the material was discharged to obtain a water-based polyurethane resin for shoe lining leather.

[0044] Comparative Example 1

[0045] Comparative example 1 is substantially the same as embodiment 1, except that: polyether glycol all adopts polytetrahydrofuran diol 2000 (PTMG2000).

[0046] Comparative Example 2

[0047] Comparative Example 2 is substantially the same as Example 1, except that 4,4'-dicyclohexylmethane diisocyanate (HMDI) is used instead of TDI in Example 1.

[0048] Comparative Example 3

[0049] Comparative Examples 3 is substantially the same as Example 1, and difference is: adopt polytetrahydrofuran diol 1000 (PTMG1000) to replace the polytetrahydrofuran diol 2000 (PTMG2000) of Example 1.

[0050] Comparative Example 4

[0051] Comparative Example 4 is basically the same as Example 1, except that the added amount of 2,2′-dimethylolpropionic acid is 25 parts.

[0052] Comparative Example 5

[0053] Comparative Example 5 is basically the same as Example 1, except that the prepolymerization temperature is 90° C. and the prepolymerization time is 4 h.

[0054] Comparative Example 6

[0055] Comparative Example 6 is basically the same as Example 1, except that the prepolymer temperature is lowered to 10° C. before emulsification, and then chain extension and desolvation are performed.

[0056] The aqueous polyurethane resins of Examples 1 to 6 and Comparative Examples 1 to 6 were prepared into resin slurries, which were coated on synthetic leather base fabrics as foaming layers to prepare shoe lining leather. The resin slurries included: 100 parts of aqueous polyurethane resin for shoe lining leather, 0.5 parts of thickener, 1 part of black pulp, and 150 parts of heavy calcium carbonate. The mixture was stirred until the viscosity of the mixture reached 25,000 CPS, and the foam was stabilized for 10 minutes.

[0057] The shoe lining leather is prepared by the following method: applying the foaming layer slurry on the mercerized velvet with a scraping thickness of 80 silk, placing it at 80℃ for 30 minutes after scraping, taking it out and placing it in a 120℃ oven for drying to obtain the shoe lining leather.

[0058] The waterborne polyurethane resins used in Examples 1 to 6 and Comparative Examples 1 to 6 were tested with reference to the standard GB / T 19250-2013, where PDI is the polydispersity index. The results are shown in Table 2.

[0059] Table 2 Performance test results of waterborne polyurethane resins of Examples 1 to 6 and Comparative Examples 1 to 6

[0060]

[0061] The shoe lining leathers prepared in Examples 1-6 and Comparative Examples 1-6 were tested for peel strength according to the standard GB-T2791-1995, and for flexural properties according to the standard GB / T3903.1-2008. The results are shown in Table 3. The evaluation criteria for leather smoothness are as follows: Excellent refers to a leather surface that is smooth and free of irregularities; Good refers to a leather surface that is substantially smooth with slight irregularities; and Poor refers to a leather surface that has a significant number of irregularities.

[0062] Table 3 Performance test results of dry pressure transformer bass of Examples 1 to 6 and Comparative Examples 1 to 6

[0063]

[0064] As can be seen from the data in Tables 2 and 3, Examples 1 to 6 use a low molecular weight polyol in combination with a small amount of a high molecular weight polyol, and use TDI with higher reactivity. The resulting waterborne polyurethane resin has a larger particle size and a wider particle size distribution. As a result, the amount of filler added in Examples 1 to 6 reaches 150 parts, and the air permeability, moisture permeability, folding resistance, and hand feel are relatively excellent.

[0065] Comparative Example 1 used a high molecular weight, single-use polyol. The resulting waterborne polyurethane resin had a high molecular weight, a narrow particle size distribution, and a low filler content. Consequently, the leather exhibited poor air and moisture permeability and a stiff feel. Comparative Example 2 used HMDI, a low-reactivity isocyanate, resulting in a small polyurethane resin with a narrow molecular weight distribution. The low filler content resulted in poor air and moisture permeability and a stiff feel. Comparative Example 3 used PTMG1000 instead of PTMG2000, employing only two polyols. This resulted in a more regular structure and a low maximum filler content. The leather exhibited poor air and moisture permeability and a stiff feel. Comparative Example 4 used 25 parts DMPA. The emulsion produced in Comparative Example 4 had the smallest particle size and the narrowest particle size distribution, the lowest filler content, the stiffest feel, and the worst air and moisture permeability. In Comparative Example 5, the prepolymerization stage temperature was 90°C. Prepolymerization at 90°C results in essentially equal reactivity of the two isocyanate groups of TDI. The resulting resin has a regular molecular chain structure, requires minimal filler, and exhibits poor leather-like air and moisture permeability and a hard feel. In Comparative Example 6, the emulsification stage temperature was lowered to 10°C. At low temperatures, the reactivity of the residual isocyanate groups in the system with water is extremely low, leading to high diamine chain extension efficiency. The molecular chains are all extended by diamine, resulting in a regular structure and minimal filler addition. The leather-like resin exhibits poor air and moisture permeability and a relatively hard feel.

[0066] It can be seen that the emulsion prepared by the combination of the low molecular weight polyol proposed in the present invention with a small amount of high molecular weight polyol and an isocyanate with higher reaction activity has a larger particle size distribution and a larger amount of added filler than the conventional aqueous polyurethane emulsion. At the same time, the shoe lining leather prepared has high peel strength, more than 30,000 flexures at room temperature and more than 50,000 flexures at low temperature. The physical properties all meet the standards and the hand feel is soft and plump.

Claims

1. A water-based polyurethane resin for shoe lining leather, characterized in that: The raw materials include the following components in parts by weight: 100 parts of polyether polyol PTMG2000, 150 parts of polyether polyol PTMG1000, 150 parts of polyether polyol PPG1000, 5 parts of small molecule diol ethylene glycol, 16 parts of carboxylic acid type hydrophilic chain extender DMPA, 100 parts of toluene-2,4-diisocyanate, 0.08 parts of catalyst BCAT-BY20, 660 parts of acetone, 12.3 parts of neutralizer triethylamine, 1.4 parts of cross-linking agent diethylenetriamine, 1.3 parts of diamine chain extender ethylenediamine, and 640 parts of pure water; Alternatively, 200 parts of polyether polyol PTMG2000, 100 parts of polyether polyol PTMG1000, 100 parts of polyether polyol PPG1000, 5 parts of small molecule diol ethylene glycol, 16 parts of carboxylic acid type hydrophilic chain extender DMPA, 100 parts of toluene-2,4-diisocyanate, 0.08 parts of catalyst BCAT-BY20, 660 parts of acetone, 12.3 parts of neutralizer triethylamine, 1.4 parts of cross-linking agent diethylenetriamine, 1.3 parts of diamine chain extender ethylenediamine, and 640 parts of pure water; Alternatively, 100 parts of polyether polyol PTMG2000, 150 parts of polyether polyol PTMG1000, 150 parts of polyether polyol PPG1000, 5 parts of small molecule diol ethylene glycol, 16 parts of carboxylic acid type hydrophilic chain extender DMPA, 120 parts of toluene-2,4-diisocyanate, 0.08 parts of catalyst BCAT-BY20, 660 parts of acetone, 12.3 parts of neutralizer triethylamine, 1.4 parts of cross-linking agent diethylenetriamine, 1.3 parts of diamine chain extender ethylenediamine, and 640 parts of pure water; Alternatively, 100 parts of polyether polyol PTMG2000, 150 parts of polyether polyol PTMG1000, 150 parts of polyether polyol PPG1000, 10 parts of small molecule diol ethylene glycol, 12 parts of carboxylic acid type hydrophilic chain extender DMPA, 100 parts of toluene-2,4-diisocyanate, 0.08 parts of catalyst BCAT-BY20, 400 parts of acetone, 10 parts of neutralizing agent triethylamine, 1.4 parts of cross-linking agent diethylenetriamine, 1.3 parts of diamine chain extender ethylenediamine, and 640 parts of pure water; Alternatively, 100 parts of polyether polyol PTMG2000, 150 parts of polyether polyol PTMG1000, 150 parts of polyether polyol PPG1000, 10 parts of small molecule diol ethylene glycol, 12 parts of carboxylic acid type hydrophilic chain extender DMPA, 110 parts of toluene-2,4-diisocyanate, 0.08 parts of catalyst BCAT-BY20, 400 parts of acetone, 10 parts of neutralizing agent triethylamine, 1 part of cross-linking agent diethylenetriamine, 2 parts of diamine chain extender ethylenediamine, and 640 parts of pure water; Alternatively, 100 parts of polyether polyol PTMG2000, 150 parts of polyether polyol PTMG1000, 150 parts of polyether polyol PPG1000, 8 parts of small molecule diol ethylene glycol, 14 parts of carboxylic acid type hydrophilic chain extender DMPA, 110 parts of toluene-2,4-diisocyanate, 0.08 parts of catalyst BCAT-BY20, 400 parts of acetone, 11 parts of neutralizing agent triethylamine, 1 part of cross-linking agent diethylenetriamine, 2 parts of diamine chain extender ethylenediamine, and 640 parts of pure water; The method for preparing the aqueous polyurethane resin for shoe lining leather comprises the following steps: (1) Under the action of the catalyst, the polyether polyol, the carboxylic acid type hydrophilic chain extender, the small molecule diol and the isocyanate are subjected to a one-step prepolymerization reaction at 75-85° C. until the NCO value test is qualified to obtain an NCO-terminated prepolymer; (2) adding acetone to the prepolymer and stirring evenly; controlling the system temperature to 35-45°C, adding the neutralizing agent and stirring to react to form a salt; then cooling to 15-25°C, adding water and stirring to emulsify to obtain an unextended chain emulsion; (3) Adding the crosslinking agent and the diamine chain extender to the unextended emulsion, stirring and reacting for 20 to 80 minutes; vacuuming to remove acetone, thereby obtaining the water-based polyurethane resin for shoe lining leather.

2. The aqueous polyurethane resin for shoe lining leather according to claim 1, characterized in that The NCO value of the prepolymerization reaction in step (1) is 1.3% to 1.7% of the total mass fraction.

3. The aqueous polyurethane resin for shoe lining leather according to claim 1, wherein The water-based polyurethane resin for shoe lining leather is tested in accordance with GB / T 19250-2013 after film formation, and the elongation at break of the film is ≥1000%, the modulus is ≤1.5 MPa, and the strength is ≥5 MPa.

4. The use of the aqueous polyurethane resin for shoe lining leather according to claim 3, characterized in that The resin slurry is prepared and coated on the synthetic leather base cloth as a foaming layer for preparing shoe lining leather.

5. The use of the aqueous polyurethane resin for shoe lining leather according to claim 4, characterized in that The resin slurry comprises: 100 parts of the water-based polyurethane resin for shoe lining leather, 50 to 150 parts of filler, 0.1 to 1 part of thickener and 0.5 to 1.5 parts of color paste.

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