Heat-resistant polyurethane adhesive for shoes and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, in particular to a heat-resistant polyurethane adhesive for shoes and a preparation method of the heat-resistant polyurethane adhesive. No polyester polyol is added, polyether polyol is used, and yellowing is reduced. The heat-resistant intermediate used in the invention has good heat resistance and good hydrophilicity, contains an active amino functional group at a terminal group, and can be embedded into a waterborne polyurethane molecular chain, so that the problem that polyimide cannot be added into a waterborne polyurethane adhesive system in the prior art, so that the service life of the adhesive is prolonged is solved. And when polyimide is added into a waterborne polyurethane adhesive system, the compatibility is poor, the system is not compatible, and the performance is reduced. The heat-resistant polyurethane adhesive for the shoes, disclosed by the invention, has the technical effects of relatively good drawing strength, heat resistance, yellowing resistance and the like.

Description

Technical Field

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

[0002] Adhesives are essential materials in the footwear industry, widely used to bond soles to uppers, midsoles to midsoles, and other components. Shoe materials come in a variety of types, including PVC, TPU, rubber, EVA, canvas, and more. The performance of adhesives directly impacts the lifespan of shoes. The footwear industry places high demands on adhesives, specifically strong bonding strength, high toughness, excellent heat resistance, and excellent yellowing resistance.

[0003] Adhesives for footwear materials include solvent adhesives, water-based adhesives, and hot-melt adhesives. Solvent adhesives are traditional adhesives with advantages such as low production costs, mature technology, and good adhesion. The disadvantage of solvent-based adhesives is that they use large amounts of solvents, which has certain impacts on the environment and health. Hot-melt adhesives have the characteristics of strong adhesion, convenient storage, and environmental protection. However, hot-melt adhesives require heating and have certain requirements for construction conditions and construction objects. Therefore, their scope of use is also limited. Water-based adhesives use water as a solvent and have the characteristics of both solvent adhesives and hot-melt adhesives. They have the advantages of being environmentally friendly and pollution-free, and have strong adhesion. They are the type of adhesive that is more favored by the modern footwear industry.

[0004] Water-based adhesives include water-based acrylic adhesives, white latex adhesives, and water-based polyurethane adhesives. Water-based polyurethane adhesives offer strong adhesion, excellent flexibility, and good water resistance, making them suitable for bonding a variety of shoe materials. Therefore, water-based polyurethane adhesives are currently the most widely used.

[0005] CN115820190A discloses a graphyne-modified water-based polyurethane adhesive. This invention introduces graphyne material into polyurethane chain segments. The prepared graphyne-modified water-based polyurethane adhesive exhibits good initial adhesion, peel strength, hydrolysis resistance and aging resistance, and can be used in the bonding of materials such as shoes and leather.

[0006] CN112961641A discloses a PVC-grafted waterborne polyurethane adhesive. This invention uses an in-situ free radical reaction to graft MAH onto the PVC surface, creating a bridging effect. Then, by controlling the reaction conditions, MAH undergoes a monoesterification reaction, which then esterifies with a trihydroxy polyol to produce a PVC-modified diol, which serves as a hydrophilic chain extender for the waterborne polyurethane. This improves the polyurethane adhesive's wettability and compatibility with materials like shoes and leather, while increasing the interfacial force between the adhesive and the material, thereby enhancing peel strength.

[0007] CN106978129A discloses a high-solid content two-component waterborne polyurethane adhesive with low-temperature activation. The invention introduces a mixed polyol with an incompletely regular molecular structure as a soft segment raw material, a mixed polyisocyanate with a certain hardness and length, and a small molecule chain extender with a regular structure as a hard segment during the preparation process of the waterborne polyurethane adhesive to regulate the molecular structure and crystallization rate of the waterborne polyurethane adhesive to achieve its low-temperature activation. The prepared waterborne adhesive has high peel strength and good heat resistance, can be used for bonding shoe materials, automotive interior materials, etc., and has great economic value.

[0008] In the hot summer, shoe materials often experience debonding and yellowing. Therefore, higher heat resistance is required for shoe adhesives. While researchers have conducted extensive research on water-based polyurethane adhesives for shoe applications, challenges remain regarding heat resistance and yellowing resistance. A water-based polyurethane adhesive with high pull-out strength, heat resistance, and yellowing resistance is urgently needed. Summary of the Invention

[0009] To address the above technical problems, the present invention provides a heat-resistant polyurethane adhesive for shoes. This water-based polyurethane adhesive exhibits excellent pull-out strength, heat resistance, and yellowing resistance. The present invention also provides a process for preparing the heat-resistant polyurethane adhesive for shoes.

[0010] The heat-resistant polyurethane adhesive for shoes provided by the present invention is prepared from the following raw materials: 80 parts of polyether polyol; 30-45 parts of isocyanate; 10-20 parts of heat-resistant intermediate; 5-10 parts of hydrophilic chain extender; 3-8 parts of amine chain extender; 3-5 parts of post-chain extender; 1-3 parts of catalyst; 15-25 parts of neutralizer; 30-80 parts of solvent; 100-150 parts of deionized water.

[0011] The polyether polyol is one or a combination of two or more of polytetramethylene glycol, polyethylene glycol, and polypropylene glycol, and the molecular weight of the polyether polyol is 1000-3000; The isocyanate is one or a combination of isophorone diisocyanate and hexamethylene diisocyanate; The hydrophilic chain extender is one or a combination of dimethylol propionic acid DMPA and dimethylol butyric acid DMBA; The amine chain extender is sodium ethylenediamine sulfonate; The post-chain extender is ethylenediamine; The catalyst is dibutyltin dilaurate; The neutralizing agent is triethylamine; The solvent is one or a combination of two or more of acetone, butanone and ethyl acetate.

[0012] The heat-resistant intermediate is a water-soluble polyimide, and the preparation method of the heat-resistant intermediate is as follows: Step (1): adding 0.1-0.5 mol of aminosulfonic acid monomer and 200-500 ml of solvent into a stirring container equipped with a reflux device, stirring and dissolving for 10-20 minutes to obtain a mixed solution 1; Step (2): adding 0.05-0.5 mol of anhydride monomer to the mixed solution 1 of step (1), reacting at room temperature for 20-25 hours to obtain a mixed solution 2 containing a condensate; Step (3): After adding 50-150 ml of the water-carrying agent to the mixed solution 2 described in step (2), stirring and heating to 175-185°C, reflux reaction for 6-8 hours, cooling, precipitating and washing the product in a poor solvent, and then vacuum drying at 80-100°C for 8-10 hours to obtain a heat-resistant intermediate.

[0013] Wherein, the aminosulfonic acid monomer is one or a combination of two or more of 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, and 2,2-benzidine disulfonic acid; The acid anhydride monomer is one or a combination of two or more of pyromellitic dianhydride, cyclobutanetetracarboxylic dianhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride; The molar ratio of the aminosulfonic acid monomer to the anhydride monomer is 1:0.9; The solvent of step (1) includes one or a combination of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF); The water-carrying agent includes one or a combination of toluene and xylene; The poor solvent in step (3) includes one or a combination of two or more of ethanol, acetone, and isopropanol; The preparation method of the heat-resistant polyurethane adhesive for shoes is as follows: Step (1): vacuum dehydrating the polyether polyol at 90-100°C for 1-2h, cooling to 45-60°C, introducing nitrogen protection, adding isocyanate, hydrophilic chain extender, and catalyst, reacting at 70-90°C for 2-5h, then cooling to 55-60°C, adding amine chain extender and heat-resistant intermediate, and continuing to react for 2-3h. After the reaction is completed, adding solvent and neutralizer, stirring at room temperature for 30-40min, and obtaining a polyurethane prepolymer; Step (2): adding deionized water to the polyurethane prepolymer obtained in step (1), stirring at high speed for 30-40 minutes, with the stirring speed of the stirrer being 1000-2000 r / min, then adding a post-chain extender and stirring for 30-50 minutes, and evaporating the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This application does not add polyester polyols, but uses polyether polyols, which reduces yellowing. The heat-resistant intermediate used in this application is a water-soluble polyimide, which has good heat resistance and good hydrophilicity. The end group contains an active amino functional group and can be embedded in the water-based polyurethane molecular chain, which solves the problem that polyimide cannot be added to the water-based polyurethane adhesive system in the prior art, and the poor compatibility and system incompatibility that occur when polyimide is added to the water-based polyurethane adhesive system, resulting in performance degradation. Through the technical solution of this application, the pull-out strength, heat resistance and yellowing resistance of the polyurethane adhesive are improved. This application further selects the raw materials of the heat-resistant intermediate and explores the dosage of the heat-resistant intermediate to obtain better pull-out strength, heat resistance and yellowing resistance. DETAILED DESCRIPTION

[0015] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0016] Synthesis example 1: A method for preparing a heat-resistant intermediate: Step (1): 0.1 mol of 2,4-diaminobenzenesulfonic acid (18.8 g) and 300 ml of DMSO were added to a stirring container equipped with a reflux device, and stirred and dissolved for 15 minutes to obtain a mixed solution 1; Step (2): adding 0.09 mol of cyclobutanetetracarboxylic dianhydride (17.6 g) to the mixed solution 1 of step (1), and reacting at room temperature for 20 hours to obtain a mixed solution 2 containing a condensate; Step (3): After adding 60 ml of water-carrying agent to the mixed solution 2 described in step (2), the mixture was stirred and heated to 180°C, and refluxed for 8 hours. After cooling, the product was precipitated and washed in ethanol, and then vacuum-dried at 90°C for 8 hours to obtain a heat-resistant intermediate I.

[0017] Synthesis example 2: A method for preparing a heat-resistant intermediate: Step (1): 0.1 mol of 2,2-benzidine disulfonic acid (34.4 g) and 500 ml of DMF were added to a stirring container equipped with a reflux device, and stirred and dissolved for 20 minutes to obtain a mixed solution 1; Step (2): adding 0.09 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride (26.5 g) to the mixed solution 1 of step (1), and reacting at room temperature for 22 hours to obtain a mixed solution 2 containing a condensate; Step (3): After adding 90 ml of xylene to the mixed solution 2 described in step (2), the mixture was heated to 180°C with stirring and refluxed for 7 hours. After cooling, the product was precipitated and washed in ethanol, and then vacuum-dried at 90°C for 8 hours to obtain a heat-resistant intermediate II.

[0018] Example 1: A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polytetramethylene ether glycol PTMEG2000, 35 parts of isophorone diisocyanate, 12 parts of heat-resistant intermediate I, 6 parts of dihydroxymethylpropionic acid DMPA, 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 1 part of dibutyltin dilaurate, 15 parts of triethylamine, 50 parts of acetone, and 120 parts of deionized water.

[0019] (2) 80 parts of polytetramethylene ether glycol PTMEG2000 were vacuum dehydrated at 95°C for 1 hour, cooled to 50°C, and nitrogen was introduced for protection. 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethyl propionic acid DMPA, and 1 part of dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. The mixture was then cooled to 55°C, and 3 parts of sodium ethylenediamine sulfonate and 12 parts of heat-resistant intermediate I were added. The reaction was continued for 2 hours. After the reaction was completed, 50 parts of acetone and 15 parts of triethylamine were added, and the mixture was stirred at room temperature for 35 minutes to obtain a polyurethane prepolymer. (3) Add 120 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 30 minutes at a stirrer speed of 1000 r / min, then add 3 parts of ethylenediamine and stir and react for 40 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0020] Example 2: A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polytetramethylene ether glycol PTMEG2000, 35 parts of isophorone diisocyanate, 12 parts of heat-resistant intermediate II, 6 parts of dihydroxymethylpropionic acid DMPA, 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 1 part of dibutyltin dilaurate, 15 parts of triethylamine, 50 parts of acetone, and 120 parts of deionized water.

[0021] (2) 80 parts of polytetramethylene ether glycol PTMEG2000 were vacuum dehydrated at 95°C for 1 hour, cooled to 50°C, and nitrogen was introduced for protection. 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethyl propionic acid DMPA, and 1 part of dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. The mixture was then cooled to 55°C, and 3 parts of sodium ethylenediamine sulfonate and 12 parts of heat-resistant intermediate II were added. The reaction was continued for 2 hours. After the reaction was completed, 50 parts of acetone and 15 parts of triethylamine were added, and the mixture was stirred at room temperature for 35 minutes to obtain a polyurethane prepolymer. (3) Add 120 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 30 minutes at a stirrer speed of 1000 r / min, then add 3 parts of ethylenediamine and stir and react for 40 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0022] Example 3: A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polypropylene glycol PPG2000, 35 parts of hexamethylene diisocyanate, 15 parts of heat-resistant intermediate II, 6 parts of dihydroxymethylbutyric acid DMBA, 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 2 parts of dibutyltin dilaurate, 16 parts of triethylamine, 60 parts of acetone, and 100 parts of deionized water.

[0023] (2) 80 parts of polypropylene glycol PPG2000 were vacuum dehydrated at 90°C for 2 hours, cooled to 45°C, and nitrogen was introduced for protection. 35 parts of hexamethylene diisocyanate, 6 parts of dihydroxymethylbutyric acid DMBA, and 2 parts of dibutyltin dilaurate were added and reacted at 80°C for 2.5 hours. The temperature was then cooled to 60°C, and 3 parts of sodium ethylenediamine sulfonate and 15 parts of heat-resistant intermediate II were added. The reaction was continued for 3 hours. After the reaction was completed, 60 parts of acetone and 16 parts of triethylamine were added and stirred at room temperature for 40 minutes to obtain a polyurethane prepolymer. (3) Add 100 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 35 minutes at a stirrer speed of 1500 r / min, then add 3 parts of ethylenediamine and stir for 30 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0024] Example 4 A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polytetramethylene ether glycol PTMEG2000, 35 parts of isophorone diisocyanate, 10 parts of heat-resistant intermediate I, 6 parts of dihydroxymethylpropionic acid DMPA, 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 1 part of dibutyltin dilaurate, 15 parts of triethylamine, 50 parts of acetone, and 120 parts of deionized water.

[0025] (2) 80 parts of polytetramethylene ether glycol PTMEG2000 were vacuum dehydrated at 95°C for 1 hour, cooled to 50°C, and nitrogen was introduced for protection. 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethyl propionic acid DMPA, and 1 part of dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. The mixture was then cooled to 55°C, and 3 parts of sodium ethylenediamine sulfonate and 10 parts of heat-resistant intermediate I were added. The reaction was continued for 2 hours. After the reaction was completed, 50 parts of acetone and 15 parts of triethylamine were added, and the mixture was stirred at room temperature for 35 minutes to obtain a polyurethane prepolymer. (3) Add 120 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 30 minutes at a stirrer speed of 1000 r / min, then add 3 parts of ethylenediamine and stir and react for 40 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0026] Example 5 A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polytetramethylene ether glycol PTMEG2000, 35 parts of isophorone diisocyanate, 15 parts of heat-resistant intermediate I, 6 parts of dihydroxymethylpropionic acid DMPA, 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 1 part of dibutyltin dilaurate, 15 parts of triethylamine, 50 parts of acetone, and 120 parts of deionized water.

[0027] (2) 80 parts of polytetramethylene ether glycol PTMEG2000 were vacuum dehydrated at 95°C for 1 hour, cooled to 50°C, and nitrogen was introduced for protection. 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethylpropionic acid DMPA, and 1 part of dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. The mixture was then cooled to 55°C, and 3 parts of sodium ethylenediamine sulfonate and 15 parts of heat-resistant intermediate I were added. The reaction was continued for 2 hours. After the reaction was completed, 50 parts of acetone and 15 parts of triethylamine were added, and the mixture was stirred at room temperature for 35 minutes to obtain a polyurethane prepolymer. (3) Add 120 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 30 minutes at a stirrer speed of 1000 r / min, then add 3 parts of ethylenediamine and stir and react for 40 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0028] Example 6 A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polytetramethylene ether glycol PTMEG2000, 35 parts of isophorone diisocyanate, 20 parts of heat-resistant intermediate I, 6 parts of dihydroxymethylpropionic acid DMPA, 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 1 part of dibutyltin dilaurate, 15 parts of triethylamine, 50 parts of acetone, and 120 parts of deionized water.

[0029] (2) 80 parts of polytetramethylene ether glycol PTMEG2000 were vacuum dehydrated at 95°C for 1 hour, cooled to 50°C, and nitrogen was introduced for protection. 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethyl propionic acid DMPA, and 1 part of dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. The mixture was then cooled to 55°C, and 3 parts of sodium ethylenediamine sulfonate and 20 parts of heat-resistant intermediate I were added. The reaction was continued for 2 hours. After the reaction was completed, 50 parts of acetone and 15 parts of triethylamine were added, and the mixture was stirred at room temperature for 35 minutes to obtain a polyurethane prepolymer. (3) Add 120 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 30 minutes at a stirrer speed of 1000 r / min, then add 3 parts of ethylenediamine and stir and react for 40 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0030] Comparative Example 1 A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polytetramethylene glycol (PTMEG2000), 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethyl propionic acid (DMPA), 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 1 part of dibutyltin dilaurate, 15 parts of triethylamine, 50 parts of acetone, and 120 parts of deionized water.

[0031] (2) 80 parts of polytetramethylene ether glycol PTMEG2000 were vacuum dehydrated at 95°C for 1 hour, cooled to 50°C, and nitrogen was introduced for protection. 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethyl propionic acid DMPA, and 1 part of dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. The mixture was then cooled to 55°C, and 3 parts of sodium ethylenediaminesulfonate were added. The reaction was continued for 2 hours. After the reaction was completed, 50 parts of acetone and 15 parts of triethylamine were added, and the mixture was stirred at room temperature for 35 minutes to obtain a polyurethane prepolymer. (3) Add 120 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 30 minutes at a stirrer speed of 1000 r / min, then add 3 parts of ethylenediamine and stir and react for 40 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0032] Comparative Example 2 A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polytetramethylene ether glycol PTMEG2000, 35 parts of isophorone diisocyanate, 8 parts of heat-resistant intermediate I, 6 parts of dihydroxymethylpropionic acid DMPA, 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 1 part of dibutyltin dilaurate, 15 parts of triethylamine, 50 parts of acetone, and 120 parts of deionized water.

[0033] (2) 80 parts of polytetramethylene ether glycol PTMEG2000 were vacuum dehydrated at 95°C for 1 hour, cooled to 50°C, and nitrogen was introduced for protection. 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethyl propionic acid DMPA, and 1 part of dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. The mixture was then cooled to 55°C, and 3 parts of sodium ethylenediamine sulfonate and 8 parts of heat-resistant intermediate I were added. The reaction was continued for 2 hours. After the reaction was completed, 50 parts of acetone and 15 parts of triethylamine were added, and the mixture was stirred at room temperature for 35 minutes to obtain a polyurethane prepolymer. (3) Add 120 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 30 minutes at a stirrer speed of 1000 r / min, then add 3 parts of ethylenediamine and stir and react for 40 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0034] Comparative Example 3 A method for preparing a heat-resistant polyurethane adhesive for shoes comprises the following steps: (1) Weigh the following raw materials: 80 parts of polytetramethylene ether glycol PTMEG2000, 35 parts of isophorone diisocyanate, 24 parts of heat-resistant intermediate I, 6 parts of dihydroxymethylpropionic acid DMPA, 3 parts of sodium ethylenediamine sulfonate, 3 parts of ethylenediamine, 1 part of dibutyltin dilaurate, 15 parts of triethylamine, 50 parts of acetone, and 120 parts of deionized water.

[0035] (2) 80 parts of polytetramethylene ether glycol PTMEG2000 were vacuum dehydrated at 95°C for 1 hour, cooled to 50°C, and nitrogen was introduced for protection. 35 parts of isophorone diisocyanate, 6 parts of dihydroxymethyl propionic acid DMPA, and 1 part of dibutyltin dilaurate were added, and the mixture was reacted at 75°C for 3 hours. The mixture was then cooled to 55°C, and 3 parts of sodium ethylenediamine sulfonate and 24 parts of heat-resistant intermediate I were added. The reaction was continued for 2 hours. After the reaction was completed, 50 parts of acetone and 15 parts of triethylamine were added, and the mixture was stirred at room temperature for 35 minutes to obtain a polyurethane prepolymer. (3) Add 120 parts of deionized water to the polyurethane prepolymer obtained in step (2), stir at high speed for 30 minutes at a stirrer speed of 1000 r / min, then add 3 parts of ethylenediamine and stir and react for 40 minutes, and evaporate the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

[0036] Performance testing: Test 1 (Pull-Out Strength Test): PVC / PVC was tested. The test substrate was cut into 10mm*10mm squares. The two substrates were bonded together using the heat-resistant polyurethane adhesive. The bonding area was 10mm*10mm and the adhesive was applied to a thickness of 0.15mm. The adhesive was pressed together with a force of 1MPa for 20s. The adhesive was then dried at 60°C for 1h. After 24h, the two test pieces were pulled apart perpendicular to the bonding surface using a tensile testing machine (tensile speed 5mm / min).

[0037] Test 2 (heat resistance test): The pull-out strength test specimen obtained in Test 1 was placed in an oven at 70°C for 72 hours. After removal, a pull-out strength test was performed.

[0038] Test 3 (Tensile Strength Retention): The tensile strength after heat aging obtained in Test 2 is divided by the tensile strength obtained in Test 1 × 100% to obtain the tensile strength retention.

[0039] Test 4 (yellowing resistance test): Apply 0.15mm thick glue on 1mm thick optical glass, then dry at 60℃ for 1h. Place the sample in a UV aging box at 60℃ and 0.86w / cm 2 , place it for 240 hours, and test the yellowing index of the sample after aging.

[0040] Table 1 Performance test results of heat-resistant polyurethane adhesives for shoes obtained in various embodiments and comparative examples

[0041] The above experimental results demonstrate that by adding an appropriate amount of the heat-resistant intermediates I / II prepared according to the present invention to a polyurethane adhesive formulation, the resulting polyurethane adhesive exhibits significant improvements in both pull-out strength and heat resistance. Furthermore, a comparison of Example 2 with Example 1 demonstrates that the heat-resistant polyurethane adhesive prepared using the heat-resistant intermediate II obtained in Synthesis Example 2 exhibits superior pull-out strength, heat resistance, and yellowing resistance compared to the heat-resistant intermediate I obtained in Synthesis Example 1. Comparisons of Comparative Examples 1-3 with Example 1 demonstrate that by limiting the amount of heat-resistant intermediate I, even better pull-out strength, heat resistance, pull-out strength retention, and yellowing resistance can be achieved.

[0042] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the defined scope, they should all fall within the scope of protection of the present invention.

Claims

1. A heat-resistant polyurethane adhesive for shoes, characterized in that: The heat-resistant polyurethane adhesive for shoes is prepared from the following raw materials: 80 parts of polyether polyol; 30-45 parts of isocyanate; 10-20 parts of heat-resistant intermediate; 5-10 parts of hydrophilic chain extender; 3-8 parts of amine chain extender; 3-5 parts of post-chain extender; 1-3 parts of catalyst; 15-25 parts of neutralizer; 30-80 parts of solvent; 100-150 parts of deionized water.

2. A heat-resistant polyurethane adhesive for shoes according to claim 1, characterized in that: The polyether polyol is one or a combination of two or more of polytetramethylene glycol, polyethylene glycol, and polypropylene glycol, and the molecular weight of the polyether polyol is 1000-3000.

3. The heat-resistant polyurethane adhesive for shoes according to claim 1, characterized in that: The isocyanate is one or a combination of isophorone diisocyanate and hexamethylene diisocyanate; and the hydrophilic chain extender is one or a combination of dimethylol propionic acid (DMPA) and dimethylol butyric acid (DMBA).

4. The heat-resistant polyurethane adhesive for shoes according to claim 1, characterized in that: The amine chain extender is sodium ethylenediamine sulfonate; the post-chain extender is ethylenediamine; the catalyst is dibutyltin dilaurate; and the neutralizer is triethylamine.

5. The heat-resistant polyurethane adhesive for shoes according to claim 1, characterized in that: The preparation method of the heat-resistant intermediate is as follows: Step (1): adding 0.1-0.5 mol of aminosulfonic acid monomer and 200-500 ml of solvent into a stirring container equipped with a reflux device, stirring and dissolving for 10-20 minutes to obtain a mixed solution 1; Step (2): adding 0.05-0.5 mol of anhydride monomer to the mixed solution 1 of step (1), reacting at room temperature for 20-25 hours to obtain a mixed solution 2 containing a condensate; Step (3): After adding 50-150 ml of the water-carrying agent to the mixed solution 2 described in step (2), stirring and heating to 175-185°C, reflux reaction for 6-8 hours, cooling, precipitating and washing the product in a poor solvent, and then vacuum drying at 80-100°C for 8-10 hours to obtain a heat-resistant intermediate.

6. The heat-resistant polyurethane adhesive for shoes according to claim 5, characterized in that: The aminosulfonic acid monomer is one or a combination of two or more of 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, and 2,2-benzidine disulfonic acid.

7. The heat-resistant polyurethane adhesive for shoes according to claim 5, characterized in that: The acid anhydride monomer is one or a combination of two or more of pyromellitic dianhydride, cyclobutanetetracarboxylic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride.

8. The heat-resistant polyurethane adhesive for shoes according to claim 5, characterized in that: The molar ratio of the aminosulfonic acid monomer to the anhydride monomer is 1:0.

9.

9. The heat-resistant polyurethane adhesive for shoes according to claim 5, characterized in that: The solvent of step (1) includes one or a combination of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF); the water-carrying agent includes one or a combination of toluene and xylene.

10. The process for preparing a heat-resistant polyurethane adhesive for shoes according to claims 1-9, characterized in that: The steps include: Step (1): vacuum dehydrating the polyether polyol at 90-100°C for 1-2h, cooling to 45-60°C, introducing nitrogen protection, adding isocyanate, hydrophilic chain extender, and catalyst, reacting at 70-90°C for 2-5h, then cooling to 55-60°C, adding amine chain extender and heat-resistant intermediate, and continuing to react for 2-3h. After the reaction is completed, adding solvent and neutralizer, stirring at room temperature for 30-40min, and obtaining a polyurethane prepolymer; Step (2): adding deionized water to the polyurethane prepolymer obtained in step (1), stirring at high speed for 30-40 minutes, with the stirring speed of the stirrer being 1000-2000 r / min, then adding a post-chain extender and stirring for 30-50 minutes, and evaporating the solvent under reduced pressure to obtain a heat-resistant polyurethane adhesive for shoes.

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