A high-strength, heat-resistant adhesive for shoes and preparation method thereof

Abstract

The invention discloses a high-strength, heat-resistant shoe adhesive and a preparation method thereof, which comprises the following components by weight: 90 to 130 parts of aqueous polyurethane dispersion, 20 to 30 parts of cage-type polysilsesquioxane, 0.3 to 0.5 parts of terpene resin, 0.2 to 0.4 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 to 0.3 parts of defoamer BYK-025, and 0.3 to 0.5 parts of leveling agent BYK-345. Adding cage-type polysilsesquioxane having a rigid benzene ring structure to the adhesive can form a cross-linked network structure in the polyurethane dispersion, and the peel strength and heat resistance of the shoe adhesive are significantly improved by the formula of the cage-type polysilsesquioxane.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a high-strength, heat-resistant adhesive for shoes and a preparation method thereof. Background Art

[0002] Adhesives are adhesive materials used to bond two or more different objects together. They are important materials in modern industry and are widely used in industrial production and daily life, such as automobile manufacturing, furniture manufacturing, construction, electronics manufacturing, and footwear manufacturing. Excellent pull-out strength is an important prerequisite for determining the quality of production products. Water-based polyurethane adhesives have high bonding strength and are pollution-free. They are the best materials for shoe adhesives and have better applications than solvent-based polyurethane adhesives.

[0003] Patent CN114479742A discloses a bio-based high-crystalline water-based polyurethane adhesive for shoes, which includes the following raw materials by weight: 150-200 parts of bio-based polyester polyol; 13-16 parts of terminal hydroxyl polyether sulfonate; 28-42 parts of aliphatic diisocyanate; 1-1.4 parts of small molecule terminal hydroxyl chain extender; 1.5-3.5 parts of small molecule terminal amino chain extender; 0.02-0.05 parts of catalyst; 0.1-0.35 parts of defoamer; 0.05-0.25 parts of antibacterial agent; 0.2-0.5 parts of leveling agent; 0-2 parts of tackifying resin. Through formula design, a dibasic acid with eleven carbon straight chains is selected as the main raw material for synthesizing polyester polyol, and then the polyester polyol is used to synthesize water-based polyurethane adhesive, thereby giving the water-based polyurethane adhesive high crystallinity.

[0004] Patent CN109679543A discloses a quick-drying water-based adhesive, comprising the following components in weight: 50-100 parts of water-based polyurethane-polyvinyl acetate resin; 0-50 parts of water-based polyurethane dispersion; 0.02-0.1 parts of defoamer; 0.1-0.5 parts of wetting agent; 0.05-0.3 parts of thickener; wherein the total weight of the water-based polyurethane-polyvinyl acetate resin and the water-based polyurethane dispersion is 100 parts. Water-based polyurethane-polyvinyl acetate resin is added to the adhesive raw material components, which is a polyurethane dispersion modified by vinyl acetate, and has the advantages of high solid content (effective component solid content is 58-62wt%) and good construction performance, so that the prepared adhesive can meet the requirements of bonding strength and heat resistance while having the advantage of quick drying.

[0005] The existing research on polyurethane adhesives is basically centered around the preparation of waterborne polyurethane dispersions and the selection of adhesive components to improve their performance. Improving the performance of adhesives is still the focus and direction of research. Summary of the invention

[0006] Based on the deficiencies and needs of the prior art, the purpose of the present invention is to provide a high-strength, heat-resistant shoe adhesive and a preparation method thereof. By improving the aqueous polyurethane dispersion and adding a cage-type polysilsesquioxane with a rigid benzene ring structure to the adhesive, a cross-linked network structure can be formed in the polyurethane dispersion. The formulation of the cage-type polysilsesquioxane significantly improves the peel strength and heat resistance of the shoe adhesive.

[0007] To achieve the above-mentioned purpose and effect, one of the technical solutions adopted by the present invention is as follows: a high-strength, heat-resistant shoe adhesive, comprising the following components, in parts by weight: 90 to 130 parts of an aqueous polyurethane dispersion, 20 to 30 parts of a cage-type polysilsesquioxane, 0.3 to 0.5 parts of a terpene resin, 0.2 to 0.4 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 to 0.3 parts of a defoamer BYK-025, and 0.3 to 0.5 parts of a leveling agent BYK-345.

[0008] Furthermore, the high-strength, heat-resistant adhesive for shoes is composed of the following components, in parts by weight: 90 to 130 parts of aqueous polyurethane dispersion, 20 to 30 parts of cage-type polysilsesquioxane, 0.3 to 0.5 parts of terpene resin, 0.2 to 0.4 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 to 0.3 parts of defoaming agent BYK-025, and 0.3 to 0.5 parts of leveling agent BYK-345.

[0009] Furthermore, the high-strength, heat-resistant shoe adhesive is composed of the following components, in parts by weight: 120 parts of aqueous polyurethane dispersion, 27 parts of cage-type polysilsesquioxane, 0.4 parts of terpene resin, 0.3 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 parts of defoamer BYK-025, and 0.4 parts of leveling agent BYK-345.

[0010] Furthermore, the cage-type polysilsesquioxane is selected from one or more of trisilanolphenyl cage-type polysilsesquioxane and octaphenyl cage-type polysilsesquioxane.

[0011] Furthermore, the preparation steps of the aqueous polyurethane dispersion are as follows:

[0012] (1) Synthesis of prepolymer:

[0013] 150-200 parts of hydroxy-terminated polybutadiene and 20-30 parts of polypropylene adipate are weighed and placed in a reactor equipped with a stirrer, a thermometer and a condenser, and heated in a water bath to raise the temperature to 80-90° C., and then dehydrated for 1-2 hours under the condition of controlling the vacuum degree to be lower than 0.5 kPa; then 6-13 parts of diisocyanate are added to the reactor, and 0.5-1 part of dibutyltin dilaurate is added dropwise to react for 3-5 hours;

[0014] (2) Dilution and chain extension of prepolymer:

[0015] After the prepolymer reaction is completed, 15 to 30 parts of acrylate monomer are added, and the reactants are kept at 80 to 90°C until the NCO content reaches the theoretical value, and then the temperature is lowered to 40 to 50°C, 10 to 20 parts of 1,4-butanediol chain extender and 30 to 50 parts of sodium ethylenediaminesulfonate chain extender are added, and the prepolymer is reacted for another 35 to 45 minutes;

[0016] (3) Waterborne polyurethane dispersion:

[0017] The polymer obtained in step (2) is cooled to room temperature, the speed of the stirrer is increased to 300-400 rpm, 80-120 parts of deionized water are added, and low molecular weight organic matter is removed by reduced pressure distillation to obtain a solvent-free sulfonate-type aqueous polyurethane dispersion.

[0018] The present application adds a cage-type polysilsesquioxane having a rigid benzene ring structure to the adhesive, which can form a cross-linked network structure in the polyurethane dispersion, exhibits excellent stability in a wide temperature range, and can significantly improve the peel strength and heat resistance of the adhesive.

[0019] To achieve the above-mentioned purpose and effect, the second technical solution adopted by the present invention is as follows: a method for preparing a high-strength, heat-resistant shoe adhesive, comprising the following steps:

[0020] (1) pouring the aqueous polyurethane dispersion and cage-type polysilsesquioxane into a stirrer, heating to 40-50° C., mixing and stirring at a stirring speed of 200-300 rpm and a stirring time of 10-15 min to obtain a uniform mixture A;

[0021] (2) Cooling the mixture A to room temperature, and then sequentially adding tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 to the mixture A under continuous stirring, and adjusting the viscosity to 3000-5000 cps, thereby obtaining the high-strength, heat-resistant shoe adhesive.

[0022] Furthermore, in step (2), the stirring speed is 300-500 rpm and the stirring time is 20-30 min.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0024] (1) The aqueous polyurethane dispersion prepared by the invention does not contain organic solvents, so there is no volatile pollution, and can be effectively used as a raw material for shoe adhesives, and has excellent self-crosslinking and yellowing resistance; it can be widely used in various shoe factories, meets national and international standards, and is conducive to the export of shoe factory products.

[0025] (2) The peel strength and heat resistance of shoe adhesives are significantly improved through the formulation of cage-type polysilsesquioxane. DETAILED DESCRIPTION

[0026] The following is a specific implementation case of the present invention to further illustrate the present invention in detail. However, the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0027] Example 1

[0028] The preparation steps of an aqueous polyurethane dispersion are as follows:

[0029] (1) Synthesis of prepolymer:

[0030] 180 parts of hydroxy-terminated polybutadiene and 27 parts of polypropylene adipate were weighed and placed in a reactor equipped with a stirrer, a thermometer and a condenser, and heated in a water bath to raise the temperature to 85° C., and then dehydrated for 1 hour under the condition of controlling the vacuum degree to 0.4 kPa; then 10 parts of diisocyanate were added to the reactor, and 0.7 parts of dibutyltin dilaurate were added dropwise to react for 4 hours;

[0031] (2) Dilution and chain extension of prepolymer:

[0032] After the prepolymer reaction was completed, 25 parts of acrylate monomer were added, and the reactants were kept at 90°C until the NCO content reached the theoretical value, then the temperature was lowered to 45°C, 13 parts of 1,4-butanediol chain extender and 38 parts of sodium ethylenediaminesulfonate chain extender were added, and the prepolymer was allowed to react for another 40 minutes;

[0033] 3) Waterborne polyurethane dispersion:

[0034] The polymer obtained in step (2) was cooled to room temperature, the speed of the stirrer was increased to 300 rpm, 90 parts of deionized water were added, and low molecular weight organic matter was removed by reduced pressure distillation to obtain a solvent-free sulfonate-type aqueous polyurethane dispersion.

[0035] Unless otherwise specified, the aqueous polyurethane dispersion used in the following examples and comparative examples is the one prepared in Example 1.

[0036] Example 2

[0037] A high-strength, heat-resistant shoe adhesive consists of the following components, measured in parts by weight: 90 parts of an aqueous polyurethane dispersion, 20 parts of trisilanol phenyl cage polysilsesquioxane, 0.3 parts of a terpene resin, 0.2 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 parts of a defoamer BYK-025, and 0.3 parts of a leveling agent BYK-345.

[0038] The method for preparing the high-strength, heat-resistant shoe adhesive comprises the following steps:

[0039] (1) pouring the aqueous polyurethane dispersion and trisilanol phenyl cage polysilsesquioxane into a stirrer, heating to 40° C., mixing and stirring at a stirring speed of 200 rpm for 10 min to obtain a uniform mixture A;

[0040] (2) The mixture A is cooled to room temperature, and tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 are added to the mixture A in sequence under continuous stirring, and the viscosity is adjusted to 3000 cps, thereby obtaining the high-strength, heat-resistant shoe adhesive.

[0041] Wherein, in step (2), the stirring speed is 300 rpm and the stirring time is 20 min.

[0042] Example 3

[0043] A high-strength, heat-resistant shoe adhesive consists of the following components, measured in parts by weight: 130 parts of an aqueous polyurethane dispersion, 30 parts of octaphenyl cage polysilsesquioxane, 0.5 parts of a terpene resin, 0.4 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.3 parts of a defoamer BYK-025, and 0.5 parts of a leveling agent BYK-345.

[0044] The method for preparing the high-strength, heat-resistant shoe adhesive comprises the following steps:

[0045] (1) pouring the aqueous polyurethane dispersion and octaphenyl cage polysilsesquioxane into a stirrer, heating to 50° C., mixing and stirring at a stirring speed of 300 rpm for 15 min to obtain a uniform mixture A;

[0046] (2) The mixture A is cooled to room temperature, and tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 are added to the mixture A in sequence under continuous stirring, and the viscosity is adjusted to 5000 cps, thereby obtaining the high-strength, heat-resistant shoe adhesive.

[0047] Wherein, in step (2), the stirring speed is 500 rpm and the stirring time is 30 min.

[0048] Example 4

[0049] A high-strength, heat-resistant adhesive for shoes consists of the following components, measured in parts by weight: 120 parts of an aqueous polyurethane dispersion, 27 parts of octaphenyl cage polysilsesquioxane, 0.4 parts of a terpene resin, 0.3 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 parts of a defoamer BYK-025, and 0.4 parts of a leveling agent BYK-345.

[0050] The method for preparing the high-strength, heat-resistant shoe adhesive comprises the following steps:

[0051] (1) pouring the aqueous polyurethane dispersion and octaphenyl cage polysilsesquioxane into a stirrer, heating to 45° C., mixing and stirring at a stirring speed of 250 rpm for 12 min to obtain a uniform mixture A;

[0052] (2) The mixture A is cooled to room temperature, and tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 are added to the mixture A in sequence under continuous stirring, and the viscosity is adjusted to 4200 cps, thereby obtaining the high-strength, heat-resistant shoe adhesive.

[0053] Wherein, in step (2), the stirring speed is 400 rpm and the stirring time is 25 min.

[0054] In order to better examine and compare the role and effect of cage-type polysilsesquioxane in adhesives, the following comparative examples are provided.

[0055] Comparative Example 1

[0056] A shoe adhesive consists of the following components, measured in parts by weight: 90 parts of an aqueous polyurethane dispersion, 0.3 parts of a terpene resin, 0.2 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 parts of a defoaming agent BYK-025, and 0.3 parts of a leveling agent BYK-345.

[0057] The preparation method of the adhesive comprises the following steps:

[0058] (1) pouring the aqueous polyurethane dispersion into a stirrer, heating it to 40° C. and stirring it at a stirring speed of 200 rpm for 10 min to obtain component A;

[0059] (2) Component A was cooled to room temperature, and tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 were added to component A in sequence under continuous stirring, and the viscosity was adjusted to 3000 cps to obtain the shoe adhesive.

[0060] Wherein, in step (2), the stirring speed is 300 rpm and the stirring time is 20 min.

[0061] Comparative Example 2

[0062] A shoe adhesive consists of the following components, measured in parts by weight: 130 parts of an aqueous polyurethane dispersion, 0.5 parts of a terpene resin, 0.4 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.3 parts of a defoaming agent BYK-025, and 0.5 parts of a leveling agent BYK-345.

[0063] The preparation method of the shoe adhesive comprises the following steps:

[0064] (1) pouring the aqueous polyurethane dispersion into a stirrer, heating it to 50° C. and stirring it at a stirring speed of 300 rpm for 15 min to obtain component A;

[0065] (2) Component A was cooled to room temperature, and tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 were added to component A in sequence under continuous stirring, and the viscosity was adjusted to 5000 cps to obtain the shoe adhesive.

[0066] Wherein, in step (2), the stirring speed is 500 rpm and the stirring time is 30 min.

[0067] Comparative Example 3

[0068] A shoe adhesive consists of the following components, measured in parts by weight: 120 parts of an aqueous polyurethane dispersion, 0.4 parts of a terpene resin, 0.3 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 parts of a defoaming agent BYK-025, and 0.4 parts of a leveling agent BYK-345.

[0069] The preparation method of the shoe adhesive comprises the following steps:

[0070] (1) pouring the aqueous polyurethane dispersion into a stirrer, heating it to 45° C. and stirring it at a stirring speed of 250 rpm for 12 min to obtain component A;

[0071] (2) Component A was cooled to room temperature, and tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 were added to component A in sequence under continuous stirring, and the viscosity was adjusted to 4200 cps to obtain the shoe adhesive.

[0072] Wherein, in step (2), the stirring speed is 400 rpm and the stirring time is 25 min.

[0073] Comparative Example 4

[0074] A high-strength, heat-resistant adhesive for shoes consists of the following components, measured in parts by weight: 120 parts of an aqueous polyurethane dispersion, 27 parts of octaphenyl cage polysilsesquioxane, 0.4 parts of a terpene resin, 0.3 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 parts of a defoamer BYK-025, and 0.4 parts of a leveling agent BYK-345.

[0075] The method for preparing the high-strength, heat-resistant shoe adhesive comprises the following steps:

[0076] (1) pouring the aqueous polyurethane dispersion and octaphenyl cage polysilsesquioxane into a stirrer, heating to 30° C., mixing and stirring at a stirring speed of 250 rpm for 12 min to obtain a uniform mixture A;

[0077] (2) The mixture A is cooled to room temperature, and tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 are added to the mixture A in sequence under continuous stirring, and the viscosity is adjusted to 4200 cps, thereby obtaining the high-strength, heat-resistant shoe adhesive.

[0078] Wherein, in step (2), the stirring speed is 400 rpm and the stirring time is 25 min.

[0079] The relevant properties of the high-strength, heat-resistant shoe adhesive prepared in this application were investigated, specifically the peel strength, heat resistance and yellowing performance were mainly tested.

[0080] (1) Peel strength test: The test conditions are rubber sole and PU leather upper. Cut the two into 150mm×30mm×5mm size specimens, apply adhesive evenly on one side of the two surfaces, stagger the applied surfaces and bond them together, dry at 50℃, and press at 1.2MPa for 10s. Measure the peel strength after 24h. The peel strength is measured by a tensile tester clamped at the non-overlapping parts of the rubber and PU specimens at 200mm·min -1 The measurement results are shown in Table 1.

[0081] (2) Heat resistance test: The test conditions are rubber sole and PU leather upper. Cut the two into 150mm×30mm×5mm size specimens, apply adhesive evenly on one side of the two surfaces, stagger the applied surfaces and bond them together, dry at 50℃, and press at 1.2MPa for 10s. Fix a 2Kg object at one end and fix the other end on the top surface of the oven. Control the oven temperature at 70℃ and prevent for 60min. Take out and measure the debonding length as the heat resistance data. The measurement results are shown in Table 1.

[0082] (3) The yellowing test conditions are as follows: the adhesive is evenly brushed on the surface of a rectangular white EVA, and after drying at 50°C, the sample is placed in a yellowing device and irradiated with a UV lamp for 5 hours at a temperature set at 60°C; after the test, it is compared with the standard colorimetric card to obtain the yellowing level.

[0083]

[0084] From the data in Table 1, it can be seen that the shoe adhesive prepared in the embodiment of the present invention has excellent strength and heat resistance, and the yellowing level reaches level 5. Compared with comparative examples 1-3, when no cage-type polysilsesquioxane is added, the strength and heat resistance of the obtained adhesive are significantly reduced; when no cage-type polysilsesquioxane is added, the yellowing performance of the obtained adhesive is reduced from level 5 to level 4. This shows that cage-type polysilsesquioxane plays an important role in the adhesive system.

[0085] Comparative Example 4 is basically the same as Example 4 in composition, but the difference is that the heating and stirring temperatures of the aqueous polyurethane dispersion and octaphenyl cage-type polysilsesquioxane in the preparation step (1) are different, the heating temperature of Example 4 is 45°C, and the heating temperature of Comparative Example 4 is 30°C, but the peel strength and heat resistance data are reduced, but the degree of reduction is not as good as the case where the cage-type polysilsesquioxane is not added. The reason for this may be that the higher temperature makes it easier for the aqueous polyurethane dispersion and the octaphenyl cage-type polysilsesquioxane to crosslink and form certain covalent bonds, making its main structure more firm and strong. However, the effect on yellowing is not obvious, and the yellowing level of Comparative Example 4 still reaches level 5.

[0086] The peel strength and heat resistance of shoe adhesives are significantly improved through the formulation of cage-type polysilsesquioxane.

[0087] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A high-strength, heat-resistant adhesive for shoes, characterized in that: The invention comprises the following components in parts by weight: 90 to 130 parts of aqueous polyurethane dispersion, 20 to 30 parts of cage-type polysilsesquioxane, 0.3 to 0.5 parts of terpene resin, 0.2 to 0.4 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 to 0.3 parts of defoamer BYK-025, and 0.3 to 0.5 parts of leveling agent BYK-345; The cage-type polysilsesquioxane is selected from one or more of trisilanol phenyl cage-type polysilsesquioxane and octaphenyl cage-type polysilsesquioxane; The preparation method of the high-strength, heat-resistant shoe adhesive comprises the following steps: (1) pouring the aqueous polyurethane dispersion and cage-type polysilsesquioxane into a stirrer, heating to 40-50° C., mixing and stirring at a stirring speed of 200-300 rpm and a stirring time of 10-15 min to obtain a uniform mixture A; (2) Cooling the mixture A to room temperature, and then sequentially adding tris(2,4-di-tert-butylphenyl)phosphite, leveling agent BYK-345, terpene resin, and defoaming agent BYK-025 to the mixture A under continuous stirring, and adjusting the viscosity to 3000-5000 cps, thereby obtaining the high-strength, heat-resistant shoe adhesive.

2. The high-strength, heat-resistant adhesive for shoes according to claim 1, characterized in that: The invention is composed of the following components in parts by weight: 90-130 parts of aqueous polyurethane dispersion, 20-30 parts of cage-type polysilsesquioxane, 0.3-0.5 parts of terpene resin, 0.2-0.4 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1-0.3 parts of defoaming agent BYK-025 and 0.3-0.5 parts of leveling agent BYK-345.

3. The high-strength, heat-resistant adhesive for shoes according to any one of claims 1 to 2, characterized in that: The invention is composed of the following components in parts by weight: 120 parts of aqueous polyurethane dispersion, 27 parts of cage-type polysilsesquioxane, 0.4 parts of terpene resin, 0.3 parts of tris(2,4-di-tert-butylphenyl)phosphite, 0.1 parts of defoamer BYK-025, and 0.4 parts of leveling agent BYK-345.

4. The high-strength, heat-resistant adhesive for shoes according to any one of claims 1 to 2, characterized in that: The preparation steps of the aqueous polyurethane dispersion are as follows: (1) Synthesis of prepolymer: 150-200 parts of hydroxy-terminated polybutadiene and 20-30 parts of polypropylene adipate are weighed and placed in a reactor equipped with a stirrer, a thermometer and a condenser, and heated in a water bath to raise the temperature to 80-90° C., and then dehydrated for 1-2 hours under the condition of controlling the vacuum degree to be lower than 0.5 kPa; then 6-13 parts of diisocyanate are added to the reactor, and 0.5-1 part of dibutyltin dilaurate is added dropwise to react for 3-5 hours; (2) Dilution and chain extension of prepolymer: After the prepolymer reaction is completed, 15 to 30 parts of acrylate monomer are added, and the reactants are kept at 80 to 90°C until the NCO content reaches the theoretical value, and then the temperature is lowered to 40 to 50°C, 10 to 20 parts of 1,4-butanediol chain extender and 30 to 50 parts of sodium ethylenediaminesulfonate chain extender are added, and the prepolymer is reacted for another 35 to 45 minutes; (3) Waterborne polyurethane dispersion: The polymer obtained in step (2) is cooled to room temperature, the speed of the stirrer is increased to 300-400 rpm, 80-120 parts of deionized water are added, and low molecular weight organic matter is removed by reduced pressure distillation to obtain a solvent-free sulfonate-type aqueous polyurethane dispersion.

5. The high-strength, heat-resistant adhesive for shoes according to claim 1, characterized in that: In step (2), the stirring speed is 300-500 rpm and the stirring time is 20-30 min.

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