High-strength foamed shoe material and method for producing the same

Abstract

The application discloses high-strength foamed shoe material and a preparation method thereof, and belongs to the technical field of foamed shoe material. Raw materials include EVA elastomer, polyether block polyamide elastomer, EVA-g-MAH elastomer, polyurea elastomer, reinforcing fiber and nucleating agent. The EVA elastomer provides light weight and cushioning performance, the polyether block polyamide elastomer provides wear resistance and impact resistance, the EVA-g-MAH elastomer improves the compatibility and adhesion of raw materials, the polyurea elastomer helps to improve the tear strength of the foamed shoe material, and the reinforcing fiber helps to improve the mechanical strength of the material. The polyurea elastomer contains thioureido and ureido, which are combined in the form of hydrogen bonds. The thioureido in the polyurea elastomer can form hydrogen bonds with the ureido in the reinforcing fiber, play a self-repairing role, and help to improve the fatigue resistance, resilience and tear strength of the foamed shoe material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of foamed shoe materials, and particularly relates to a high-strength foamed shoe material and a preparation method thereof. BACKGROUND

[0002] In recent years, with the progress of material technology, many manufacturers have begun to innovate in the field of shoe materials. A general shoe includes a vamp, a midsole and an outsole. The midsole provides stability, cushioning and resilience, absorbs impact generated during movement, and provides comfortable foot feeling and safety protection.

[0003] The midsole material mainly includes EVA, TPU, POE, EDPM and the like. A general foaming method is to granulate raw materials, a foaming agent and a promoter and the like, and then to foam under high temperature and high pressure by using a mold, which belongs to chemical foaming. In recent years, more and more manufacturers use supercritical foaming technology. Compared with traditional chemical foaming, supercritical foaming has obvious advantages. Carbon dioxide gas or nitrogen gas is used as a physical foaming agent. These fluids are dissolved and diffused into the polymer matrix under high temperature and high pressure, and then the gas is precipitated by rapid pressure relief, forming a pore structure with micro-nano size and high pore density, which can simultaneously provide support, cushioning and lightness, and is widely favored by consumers.

[0004] Some foamed shoe materials are prone to wrinkles and deformation during use, because the compression permanent set is too large, and the fatigue resistance and resilience of the foamed shoe material need to be improved. SUMMARY

[0005] The application aims to provide a high-strength foamed shoe material and a preparation method thereof, which improves the resilience of the foamed shoe material and reduces its compression permanent set by raw material matching.

[0006] The application can be achieved by the following technical scheme:

[0007] A preparation method of a high-strength foamed shoe material, comprising the following steps:

[0008] EVA elastomer, polyether block polyamide elastomer, EVA-g-MAH elastomer, polyurea elastomer, reinforcing fiber and nucleating agent are mixed at a mass ratio of 60-70:25-30:8-12:5-8:5-6:0.5-0.8, and then extruded and granulated by using a double-screw extruder to obtain foamed particles, which are then injection molded into a mold by using an injection machine to form a shoe material blank, the shoe material blank is placed in a foaming kettle, nitrogen is used as a supercritical gas, and the foaming kettle is foamed under a pressure of 25-28 MPa and a temperature of 145-150 DEG C by using a supercritical foaming method, and then the high-strength foamed shoe material is obtained after pressure relief.

[0009] Further, the nucleating agent is any one of nano-titanium dioxide, nano-zinc oxide and nano-calcium carbonate.

[0010] Further, the reinforcing fiber is prepared by the following steps:

[0011] Step one: bio-based lignin, polyethylene glycol 400 and glycerol are added into a reaction kettle in a mass ratio of 1:2:1 and stirred and mixed, then 98% mass fraction sulfuric acid is added into the reaction kettle, and stirring is carried out at 130-140℃ and 200-300r / min for 1.2-1.5h, and then the reaction liquid is naturally cooled, the pH value of the reaction liquid is adjusted to neutral with sodium hydroxide solution, and water is removed by rotary evaporation to obtain bio-based lignin polyol.

[0012] Step two: isophorone diisocyanate, bio-based lignin polyol and dibutyltin dilaurate are added into a reaction kettle and stirred and mixed, then the reaction kettle is incubated at 45-50℃ for 20-24h, the solidified product is washed with anhydrous ethanol for 2-3 times, and vacuum drying is carried out to obtain polyhydroxy lignin polyurethane.

[0013] Step three: polyimide containing urea group and polyhydroxy lignin polyurethane are added into a reaction kettle and dissolved with dimethyl sulfoxide, and then the spinning solution is obtained by copper mesh filtration, the spinning solution is prepared into a nanofiber membrane by electrospinning method, the nanofiber membrane is crushed and uniformly dispersed by a high-speed homogenizer, and then a reinforcing fiber with a length of 1±0.2mm is obtained.

[0014] Further, the mass ratio of isophorone diisocyanate, bio-based lignin polyol and dibutyltin dilaurate is 20:30-32:0.3.

[0015] Further, the dosage ratio of polyimide containing urea group, polyhydroxy lignin polyurethane and dimethyl sulfoxide is 10g:4-5g:50mL.

[0016] Further, the specific steps of the electrospinning method are as follows: under the environmental temperature of 20-25℃ and the environmental humidity of 40%, the spinning solution is spun by electrospinning equipment under the spinning voltage of 20-22kV, the spinning solution flow rate is 1-1.2mL / h, the drum receiving distance is 18-20cm, and the drum rotation speed is 450r / min.

[0017] Further, the polyimide containing urea group is prepared by the following steps:

[0018] Step 1: 4,4'-diaminodiphenyl ether and N,N-dimethylacetamide were added into a reaction kettle, stirred at 200-300 r / min for 15-20 min, and then isophorone diisocyanate and dibutyltin dilaurate were added into the reaction kettle, and stirred at 70-75 °C for 4.5-5 h to obtain an isocyanate-terminated polyurea solution; the amount ratio of 4,4'-diaminodiphenyl ether, N,N-dimethylacetamide, isophorone diisocyanate and dibutyltin dilaurate was 20 g: 250 mL: 23.3-24.4 g: 0.3 g.

[0019] Step 2: 4,4'-diaminodiphenyl ether and N,N-dimethylacetamide were added into a reaction kettle, stirred at 200-300 r / min for 15-20 min, and then isophorone diisocyanate and dibutyltin dilaurate were added into the reaction kettle, and stirred at 70-75 °C for 4.5-5 h to obtain an isocyanate-terminated polyurea solution; the amount ratio of 4,4'-diaminodiphenyl ether, N,N-dimethylacetamide, isophorone diisocyanate and dibutyltin dilaurate was 20 g: 250 mL: 23.3-24.4 g: 0.3 g.

[0020] Step 3: The amino-terminated polyamic acid solution and the isocyanate-terminated polyurea solution were added into a reaction kettle and stirred to mix, and then reacted at 70-75 °C for 1-1.2 h, and then biphenyl tetracarboxylic dianhydride was added into the reaction kettle as a crosslinking agent, and the reaction was continued for 4-4.5 h to obtain a polyamic acid solution containing urea groups, and then the solvent was removed by rotary evaporation, and the product was imidized at 200-220 °C for 6-8 h, and then washed with anhydrous ethanol and deionized water for 2-3 times, and then dried to obtain a polyimide containing urea groups.

[0021] Further, the amount ratio of the amino-terminated polyamic acid solution, the isocyanate-terminated polyurea solution and the biphenyl tetracarboxylic dianhydride was 250 mL: 75-100 mL: 1.2-1.6 g.

[0022] Further, the polyurea elastomer was prepared by the following steps:

[0023] 4,4'-diaminodiphenyl ether and N,N-dimethylacetamide were added into a reaction kettle, stirred at 200-300 r / min for 15-20 min, and then isophorone diisocyanate and dibutyltin dilaurate were added into the reaction kettle, and stirred at 70-75 °C for 4.5-5 h to obtain an amino-terminated prepolymer solution, and then carbon disulfide was added into the reaction kettle, and the stirring reaction was continued for 30-40 min, and then the solvent was removed by rotary evaporation, and then the product was washed with anhydrous ethanol and deionized water for 2-3 times, and then dried to obtain a polyurea elastomer.

[0024] Further, the use amount ratio of 4,4'-diaminodiphenyl ether, N,N-dimethylacetamide, isophorone diisocyanate, dibutyl tin dilaurate and carbon disulfide is 40 g: 250-300 mL: 22.2 g: 0.3-0.35 g: 7.6 g.

[0025] Advantages of the present application:

[0026] The high-strength foamed shoe material of the present application comprises EVA elastomer, polyether block polyamide elastomer, EVA-g-MAH elastomer, polyurea elastomer, reinforcing fiber and nucleating agent, wherein the EVA elastomer provides lightness and cushioning performance, the polyether block polyamide elastomer provides wear resistance and impact resistance, the EVA-g-MAH elastomer improves the compatibility and adhesion of the raw material, the polyurea elastomer helps to improve the tear strength of the foamed shoe material, and the reinforcing fiber helps to improve the mechanical strength of the material.

[0027] The reinforcing fiber of the present application can improve the strength and toughness of the foamed shoe material, and the raw material comprises polyurethane containing urea groups and polyhydroxy lignin, the addition of polyhydroxy lignin polyurethane can improve the flexibility of the reinforcing fiber and help to reduce the increase of the hardness of the foamed shoe material. The large number of hydroxyl groups contained in the hydroxyl lignin polyurethane can react with the maleic anhydride in the EVA-g-MAH elastomer during foaming, which helps to improve the compatibility of the reinforcing fiber and the matrix, reduces the formation of an interfacial layer between the nanofiber and the shoe material matrix, avoids affecting the formation of bubble nuclei, and makes the bubble distribution uniform, thereby avoiding affecting the resilience of the foamed shoe material.

[0028] The polyurea elastomer of the present application contains thioureido and urea groups, which not only combine in the form of hydrogen bonds, but also form hydrogen bonds with the urea groups in the reinforcing fiber, thereby playing a self-repairing role and helping to improve the fatigue resistance, resilience and tear strength of the foamed shoe material. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0030] Embodiment 1: The present embodiment provides a high-strength foamed shoe material, which is prepared by the following steps:

[0031] S1: 20 kg of 4,4'-diaminodiphenyl ether and 250 L of N,N-dimethylacetamide were added into a reaction kettle and stirred at 200 r / min for 15 min, 27.3 kg of biphenyl tetracarboxylic dianhydride was added into the reaction kettle and stirred at 30°C for 4.5 h to obtain an amino-terminated polyamic acid solution; 20 kg of 4,4'-diaminodiphenyl ether and 250 L of N,N-dimethylacetamide were added into a reaction kettle and stirred at 200 r / min for 15 min, 23.3 kg of isophorone diisocyanate and 0.3 kg of dibutyltin dilaurate were added into the reaction kettle and stirred at 70°C for 4.5 h to obtain an isocyanate-terminated polyurea solution.

[0032] S2: 250 L of the amino-terminated polyamic acid solution and 75 L of the isocyanate-terminated polyurea solution were added into a reaction kettle and stirred to mix, and reacted at 70°C for 1 h, then 1.2 kg of biphenyl tetracarboxylic dianhydride was added into the reaction kettle as a crosslinking agent, and the reaction was continued for 4 h to obtain a polyamic acid solution containing urea groups, the solvent was removed by rotary evaporation, and the product was imidized at 200°C for 6 h, washed with anhydrous ethanol and deionized water for 2 times respectively, and dried to obtain a polyimide containing urea groups.

[0033] S3: Bio-based lignin, polyethylene glycol 400 and glycerol were added into a reaction kettle in a mass ratio of 1:2:1 and stirred to mix, then sulfuric acid with a mass fraction of 98% was added dropwise into the reaction kettle, and stirred at 130°C and 200 r / min for 1.2 h, and then naturally cooled, the pH value of the reaction solution was adjusted to neutral with sodium hydroxide solution, and the water was removed by rotary evaporation to obtain a bio-based lignin polyol; 20 kg of isophorone diisocyanate, 30 kg of bio-based lignin polyol and 0.3 kg of dibutyltin dilaurate were added into a reaction kettle and stirred to mix, and then incubated at 45°C for 20 h, the cured product was washed with anhydrous ethanol for 2 times, and vacuum dried to obtain a polyurethane of lignin with multiple hydroxyl groups.

[0034] S4: 10 kg of the polyimide containing urea groups and 4-5 kg of the polyurethane of lignin with multiple hydroxyl groups were added into a reaction kettle and dissolved with 50 L of dimethyl sulfoxide, and then filtered through a copper mesh to obtain a spinning solution, the spinning solution was prepared into a nanofiber membrane by using an electrospinning method, and the specific steps of the electrospinning method were as follows: the spinning solution was spun by using an electrospinning device at a spinning voltage of 20 kV under the conditions of an ambient temperature of 20°C and an ambient humidity of 40%, the flow rate of the spinning solution was 1 mL / h, the receiving distance of the drum was 18 cm, and the rotating speed of the drum was 450 r / min; the nanofiber membrane was crushed, and the nanofibers were broken and uniformly dispersed by using a high-speed homogenizer to obtain reinforcing fibers with a length of 1±0.2 mm.

[0035] S5: 40 kg of 4,4'-diaminodiphenyl ether and 250-300 L of N,N-dimethylacetamide were added into a reaction kettle, stirred at 200 r / min for 15 min, 22.2 kg of isophorone diisocyanate and 0.3 kg of dibutyltin dilaurate were added into the reaction kettle, and then stirred at 70°C for 4.5 h to obtain an amino-terminated prepolymer solution, then 7.6 kg of carbon disulfide was added into the reaction kettle, and the reaction was continued for 30 min, the solvent was removed by rotary evaporation, and the product was washed with anhydrous ethanol and deionized water for 2 times respectively, and dried to obtain a polyurea elastomer.

[0036] S6: 60 kg of EVA elastomer, 25 kg of polyether block polyamide elastomer, 8 kg of EVA-g-MAH elastomer, 5 kg of polyurea elastomer in step S5, 5 kg of reinforcing fibers in step S4 and 0.5 kg of nano titanium dioxide were mixed in an internal mixer, and then extruded and granulated by a twin-screw extruder to obtain foaming particles, and then the particles were injected into a mold by an injection machine to form a shoe material blank, and then the shoe material blank was placed in a foaming kettle, and then foamed by using nitrogen as a supercritical gas at a pressure of 25 MPa and a temperature of 145°C by a supercritical foaming method, and then a high-strength foaming shoe material was obtained after pressure relief.

[0037] Example 2: A high-strength foaming shoe material is provided, which is prepared by the following steps:

[0038] S1: 20 kg of 4,4'-diaminodiphenyl ether and 250 L of N,N-dimethylacetamide were added into a reaction kettle, stirred at 250 r / min for 18 min, 27.45 kg of biphenyl tetracarboxylic dianhydride was added into the reaction kettle, and then stirred at 32°C for 4.8 h to obtain an amino-terminated polyamic acid solution; 20 kg of 4,4'-diaminodiphenyl ether and 250 L of N,N-dimethylacetamide were added into a reaction kettle, stirred at 250 r / min for 18 min, 23.85 kg of isophorone diisocyanate and 0.3 kg of dibutyltin dilaurate were added into the reaction kettle, and then stirred at 72°C for 4.8 h to obtain an isocyanate-terminated polyurea solution.

[0039] S2: 250 L of the amino-terminated polyamic acid solution and 85 L of the isocyanate-terminated polyurea solution were added into a reaction kettle and stirred and mixed, reacted at 72°C for 1.1 h, then 1.4 kg of biphenyl tetracarboxylic dianhydride was added into the reaction kettle as a crosslinking agent, and the reaction was continued for 4.2 h to obtain a polyamic acid solution containing urea groups, the solvent was removed by rotary evaporation, the product was imidized at 210°C for 7 h, washed with anhydrous ethanol and deionized water for 2 times respectively, and dried to obtain a polyimide containing urea groups.

[0040] S3: Bio-based lignin, polyethylene glycol 400 and glycerol were added into a reaction kettle in a mass ratio of 1:2:1 and stirred and mixed, then 98% mass fraction sulfuric acid was added dropwise into the reaction kettle, and stirring was carried out at 135°C and 250 r / min for 1.35 h, and then the reaction solution was naturally cooled, the pH value of the reaction solution was adjusted to neutral with sodium hydroxide solution, and water was removed by rotary evaporation to obtain bio-based lignin polyol; 20 kg of isophorone diisocyanate, 31 kg of bio-based lignin polyol and 0.3 kg of dibutyltin dilaurate were added into a reaction kettle and stirred and mixed, then the reaction kettle was kept at 48°C for 22 h, the solidified product was washed with anhydrous ethanol for 2 times, and vacuum drying was carried out to obtain polyhydroxyl lignin polyurethane.

[0041] S4: 10 kg of polyimide containing urea groups and 4.5 kg of polyhydroxyl lignin polyurethane were added into a reaction kettle and dissolved with 50 L of dimethyl sulfoxide, and then a spinning solution was obtained by filtering through a copper mesh, and the spinning solution was prepared into a nanofiber membrane by using an electrospinning method; the specific steps of the electrospinning method were as follows: the spinning solution was spun by using an electrospinning device at a spinning voltage of 21 kV under the conditions of an ambient temperature of 22°C and an ambient humidity of 40%, the flow rate of the spinning solution was 1.1 mL / h, the drum receiving distance was 19 cm, and the drum rotating speed was 450 r / min; the nanofiber membrane was crushed, and the nanofibers were broken and uniformly dispersed by using a high-speed homogenizer to obtain reinforcing fibers with a length of 1±0.2 mm.

[0042] S5: 40 kg of 4,4'-diamino diphenyl ether and 280 L of N,N-dimethylacetamide were added into a reaction kettle, stirring was carried out at 250 r / min for 18 min, 22.2 kg of isophorone diisocyanate and 0.32 kg of dibutyltin dilaurate were added into the reaction kettle, and then stirring was carried out at 72°C for 4.8 h to obtain an amino-terminated prepolymer solution, then 7.6 kg of carbon disulfide was added into the reaction kettle, and stirring was continued for 35 min, the solvent was removed by rotary evaporation, the product was washed with anhydrous ethanol and deionized water for 2 times respectively, and drying was carried out to obtain a polyurea elastomer.

[0043] S6: 65 kg of EVA elastomer, 28 kg of polyether block polyamide elastomer, 10 kg of EVA-g-MAH elastomer, 6.5 kg of polyurea elastomer in step S5, 5.5 kg of reinforcing fibers in step S4 and 0.65 kg of nano zinc oxide were mixed by banburying, and then extrusion granulation was carried out by using a double screw extruder to obtain foaming particles, and then the foaming particles were injected into a mold by using an injection machine to form a shoe material blank, the shoe material blank was placed into a foaming kettle, nitrogen was used as a supercritical gas, and the shoe material blank was foamed by using a supercritical foaming method under the conditions of a pressure of 26.5 MPa and a temperature of 148°C, and then high-strength foaming shoe material was obtained after pressure relief.

[0044] Example 3: The present embodiment provides a high-strength foamed shoe material, which is prepared by the following steps:

[0045] S1: 20 kg of 4,4'-diamino diphenyl ether and 250 L of N,N-dimethylacetamide were added to a reaction kettle and stirred at 300 r / min for 20 min. 27.6 kg of biphenyl tetracarboxylic dianhydride was added to the reaction kettle and stirred at 35°C for 5 h to obtain an amino-terminated polyamic acid solution. 20 kg of 4,4'-diamino diphenyl ether and 250 L of N,N-dimethylacetamide were added to the reaction kettle and stirred at 300 r / min for 15-20 min. 24.4 kg of isophorone diisocyanate and 0.3 kg of dibutyltin dilaurate were added to the reaction kettle and stirred at 75°C for 5 h to obtain an isocyanate-terminated polyurea solution.

[0046] S2: 250 L of the amino-terminated polyamic acid solution and 100 L of the isocyanate-terminated polyurea solution were added to the reaction kettle and stirred to mix. The mixture was reacted at 75°C for 1.2 h. Then 1.6 kg of biphenyl tetracarboxylic dianhydride was added to the reaction kettle as a crosslinking agent and the reaction was continued for 4.5 h to obtain a polyamic acid solution containing urea groups. The solvent was removed by rotary evaporation. The product was imidized at 220°C for 8 h, washed with anhydrous ethanol and deionized water for 3 times respectively, and dried to obtain a polyimide containing urea groups.

[0047] S3: Bio-based lignin, polyethylene glycol 400 and glycerol were added to the reaction kettle in a mass ratio of 1:2:1 and stirred to mix. Then 98% mass fraction sulfuric acid was added dropwise to the reaction kettle. The mixture was stirred at 140°C and 300 r / min for 1.5 h, naturally cooled, and the pH value of the reaction solution was adjusted to neutral with sodium hydroxide solution. The water was removed by rotary evaporation to obtain a bio-based lignin polyol. 20 kg of isophorone diisocyanate, 32 kg of bio-based lignin polyol, and 0.3 kg of dibutyltin dilaurate were added to the reaction kettle and stirred to mix. Then the mixture was incubated at 50°C for 24 h. The solidified product was washed with anhydrous ethanol for 3 times and vacuum dried to obtain a polyhydroxy lignin polyurethane.

[0048] S4: 10 kg urea-based polyimide, 5 kg polyhydroxy lignin polyurethane were added into a reaction kettle and dissolved with 50 L dimethyl sulfoxide, and after filtration through a copper mesh, a spinning solution was obtained. The spinning solution was prepared into a nanofiber membrane by using an electrospinning method. The specific steps of the electrospinning method were as follows: under the conditions of an ambient temperature of 25 DEG C and an ambient humidity of 40%, the spinning solution was spun by using an electrospinning device under the condition of a spinning voltage of 22 kV, a spinning solution flow rate of 1.2 mL / h, a drum receiving distance of 20 cm, and a drum rotating speed of 450 r / min; the nanofiber membrane was crushed, and the nanofibers were broken and uniformly dispersed by using a high-speed homogenizer, so that reinforcing fibers with a length of 1 ± 0.2 mm were obtained.

[0049] S5: 40 kg 4,4'-diamino diphenyl ether and 300 L N,N-dimethylacetamide were added into a reaction kettle, stirred at 300 r / min for 20 min, 22.2 kg isophorone diisocyanate and 0.35 kg dibutyltin dilaurate were added into the reaction kettle, and then stirred at 75 DEG C for 5 h to obtain an amino-terminated prepolymer solution. Then 7.6 kg carbon disulfide was added into the reaction kettle, and the stirring reaction was continued for 40 min. The solvent was removed by rotary evaporation, and the product was washed with anhydrous ethanol and deionized water for 3 times respectively, and dried to obtain a polyurea elastomer.

[0050] S6: 70 kg EVA elastomer, 30 kg polyether block polyamide elastomer, 12 kg EVA-g-MAH elastomer, 8 kg polyurea elastomer in step S5, 6 kg reinforcing fibers in step S4, and 0.8 kg nano calcium carbonate were mixed by banburying, and then extruded and granulated by using a double screw extruder to obtain foaming particles. The foaming particles were injected into a mold by using an injection machine to form a shoe material blank. The shoe material blank was placed into a foaming kettle, and foamed by using supercritical foaming under the conditions of nitrogen as a supercritical gas, a pressure of 28 MPa, and a temperature of 150 DEG C. After pressure relief, a high-strength foamed shoe material was obtained.

[0051] Comparative Example 1: On the basis of Example 3, no polyurea elastomer was added, and the remaining steps were unchanged, and a foamed shoe material was prepared.

[0052] Comparative Example 2: On the basis of Example 3, no reinforcing fiber was added, and the remaining steps were unchanged, and a foamed shoe material was prepared.

[0053] Comparative Example 3: On the basis of Example 3, the urea-based polyimide in step S4 was replaced by a commercially available polyimide, and the remaining steps were unchanged, and a foamed shoe material was prepared.

[0054] In the examples and comparative examples, the EVA elastomer was Taiwan Formosa 7470M; the polyether block polyamide elastomer was Pebax3533 from Arkema, France; and the EVA-g-MAH elastomer was Dow C250, USA.

[0055] The supercritical foaming gas saturation time in the examples and comparative examples is 4.5 h, and the pressure relief time is 30 s.

[0056] Samples were prepared according to the standard for different foamed materials in Examples 1-3 and Comparative Examples 1-3, and performance tests were conducted. The densities of different samples were tested by the drainage method according to GB / T 6343-2009; the hardness (Shore C) of different samples was tested according to ISO 2439-2008; the resilience of different samples was tested by the falling ball method according to GB / T 6670-2008; the compression permanent deformation of different samples was tested according to GB / T 6669-2008; and the tear strength of different samples was tested according to GB / T 529-2008.

[0057] The results are shown in Table 1:

[0058] Table 1

[0059] Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Density (g / cm 3 )]]> 0.18 0.17 0.17 0.15 0.14 0.20 Hardness (Shore C) 45 47 48 42 43 51 Resilience (%) 73 74 72 65 69 68 Compression set (%) 15.88 15.26 15.45 24.36 19.65 22.48 Tear strength (N / mm) 13.4 13.7 13.8 11.5 10.2 13.2

[0060] As can be seen from Table 1, the foamed shoe materials in Examples 1-3 have higher resilience and tear strength, and lower compression permanent deformation rate. The decrease in resilience and increase in compression permanent deformation in Comparative Example 1 are because the polyurea elastomer contains thioureido groups and urea groups, which not only combine with each other by hydrogen bonds, but also form hydrogen bonds with urea groups in the reinforcing fibers, thereby enhancing the overall performance of the foamed shoe material. Comparative Example 2 shows that the reinforcing fibers can improve the resilience and tear strength of the foamed shoe material, and the reinforcing fiber raw materials include polyimide containing urea groups and polyhydroxy lignin polyurethane, in which the urea groups can be crosslinked with the thioureido groups in the polyurea elastomer by hydrogen bonds. Comparative Example 3 shows that the large amount of hydroxyl groups contained in the polyhydroxy lignin polyurethane can improve the compatibility of the reinforcing fibers and the matrix, reduce the formation of an interfacial layer between the nanofibers and the shoe material matrix, avoid affecting the formation of bubble nuclei, and make the bubble hole distribution uniform, thereby avoiding affecting the resilience of the foamed shoe material.

[0061] It should be noted that in this document, terms such as "comprise", "comprising", or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles, or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or inherent to such processes, methods, articles, or devices.

[0062] Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of making a high strength foamed shoe material, characterized by, It comprises the following steps: EVA elastomer, polyether block polyamide elastomer, EVA-g-MAH elastomer, polyurea elastomer, reinforcing fiber and nucleating agent are mixed in a mass ratio of 60-70:25-30:8-12:5-8:5-6:0.5-0.8, then extruded and granulated by a double screw extruder, and then the foamed particles are obtained by injection molding into a mold by an injection machine, and then the shoe material blank is obtained, and then the shoe material blank is placed in a foaming kettle, nitrogen is used as a supercritical gas, and the shoe material is foamed by supercritical foaming at a pressure of 25-28 MPa and a temperature of 145-150 DEG C, and then the high-strength foamed shoe material is obtained after pressure relief; The nucleating agent is any one of nano-titanium dioxide, nano-zinc oxide and nano-calcium carbonate; The reinforcing fiber is prepared by the following steps: The polyurethane containing urea group and polyurea elastomer are added into the reaction kettle and dissolved by dimethyl sulfoxide, and then the spinning solution is obtained by filtering through a copper mesh, and then the nanofiber membrane is prepared by electrospinning, and then the nanofiber membrane is crushed by a high-speed homogenizer to break and uniformly disperse the nanofiber, and then the reinforcing fiber with a length of 1±0.2 mm is obtained; The polyurethane containing urea group is prepared by the following steps: The amino-terminated polyamide acid solution and the isocyanate-terminated polyurea solution are added into the reaction kettle and stirred and mixed, and then the reaction is carried out at 70-75 DEG C for 1-1.2 h, and then the reaction kettle is added with biphenyl tetracarboxylic dianhydride as a crosslinking agent, and then the reaction is continued for 4-4.5 h to obtain the polyamide acid solution containing urea group, and then the solvent is removed by rotary evaporation, and then the product is imidized at 200-220 DEG C for 6-8 h, and then the product is washed with anhydrous ethanol and deionized water for 2-3 times respectively, and then the polyurethane containing urea group is obtained by drying; The polyurea elastomer is prepared by the following steps: The 4,4'-diamino diphenyl ether and N,N-dimethylacetamide are added into the reaction kettle and stirred at 200-300 r / min for 15-20 min, and then the isophorone diisocyanate and dibutyltin dilaurate are added into the reaction kettle and stirred and reacted at 70-75 DEG C for 4.5-5 h to obtain the amino-terminated prepolymer solution, and then the carbon disulfide is added into the reaction kettle and the stirring and reaction is continued for 30-40 min, and then the solvent is removed by rotary evaporation, and then the product is washed with anhydrous ethanol and deionized water for 2-3 times respectively, and then the polyurea elastomer is obtained by drying; The reinforcing fiber raw material comprises the polyurethane containing urea group and the polyurea elastomer, and the urea group can be crosslinked with the thiourea group in the polyurea elastomer by hydrogen bonding; The specific steps of the electrospinning method are as follows: the spinning solution is spun by using an electrospinning device at a spinning voltage of 20-22 kV under the condition of an ambient temperature of 20-25 DEG C and an ambient humidity of 40%, the flow rate of the spinning solution is 1-1.2 mL / h, the receiving distance of the drum is 18-20 cm, and the rotating speed of the drum is 450 r / min.

2. The method of claim 1, wherein the high strength foamed shoe material is prepared by the steps of: The polyurethane containing urea group is prepared by the following steps: Isoflurone diisocyanate, bio-based lignin polyol, dibutyl tin dilaurate are added into a reaction kettle and stirred and mixed, then the mixture is kept at 45-50℃ for 20-24h, the cured product is washed with anhydrous ethanol for 2-3 times and dried in vacuum to obtain polyhydroxyl lignin polyurethane; the urea group-containing polyimide, polyhydroxyl lignin polyurethane and dimethyl sulfoxide are used in a ratio of 10g:4-5g:50mL.

3. The method of claim 2, wherein the high strength foamed shoe material is prepared by the steps of: The mass ratio of the isoflurone diisocyanate, bio-based lignin polyol and dibutyl tin dilaurate is 20:30-32:0.

3.

4. The method for preparing a high-strength foamed shoe material according to claim 2, characterized in that, The bio-based lignin polyol is prepared by the following steps: Bio-based lignin, polyethylene glycol 400 and glycerol are added into a reaction kettle in a mass ratio of 1:2:1 and stirred and mixed, then 98% sulfuric acid is added dropwise into the reaction kettle, and the mixture is stirred at 130-140℃ and 200-300r / min for 1.2-1.5h, then the mixture is naturally cooled, the pH value of the reaction solution is adjusted to neutral with sodium hydroxide solution, and water is removed by rotary evaporation to obtain bio-based lignin polyol.

5. The method for preparing a high-strength foamed shoe material according to claim 1, characterized in that, The amino-terminated polyamic acid solution, isocyanate-terminated polyurea solution and diphthalic anhydride are used in a ratio of 250mL:75-100mL:1.2-1.6g.

6. The method for preparing a high-strength foamed shoe material according to claim 5, characterized in that, The amino-terminated polyamic acid solution is prepared by the following steps: 4,4'-diamino diphenyl ether and N,N-dimethylacetamide are added into a reaction kettle and stirred at 200-300r / min for 15-20min, then diphthalic anhydride is added into the reaction kettle and stirred at 30-35℃ for 4.5-5h to obtain the amino-terminated polyamic acid solution; the mass ratio of 4,4'-diamino diphenyl ether, N,N-dimethylacetamide and diphthalic anhydride is 20g:250mL:27.3-27.6g.

7. The method for preparing a high-strength foamed shoe material according to claim 5, characterized in that, The isocyanate-terminated polyurea solution is prepared by the following steps: 4,4'-diamino diphenyl ether and N,N-dimethylacetamide are added into a reaction kettle and stirred at 200-300r / min for 15-20min, then isoflurone diisocyanate and dibutyl tin dilaurate are added into the reaction kettle and stirred at 70-75℃ for 4.5-5h to obtain the isocyanate-terminated polyurea solution; the mass ratio of 4,4'-diamino diphenyl ether, N,N-dimethylacetamide, isoflurone diisocyanate and dibutyl tin dilaurate is 20g:250mL:23.3-24.4g:0.3g.

8. The method for preparing a high-strength foamed shoe material according to claim 1, characterized in that, The mass ratio of 4,4'-diamino diphenyl ether, N,N-dimethylacetamide, isoflurone diisocyanate, dibutyl tin dilaurate and carbon disulfide is 40g:250-300mL:22.2g:0.3-0.35g:7.6g.

9. A high strength foamed shoe material, characterized by, The polyhydroxyl lignin polyurethane is prepared by the preparation method of any one of claims 1-8.