A shock absorbing acrylic shoe insert and method of making same

Abstract

The present application relates to the technical field of insole materials, and specifically discloses a shock-absorbing acrylic insole and a preparation method thereof. The insole is obtained by hot rolling a foamed rubber sheet and a support layer material, and the support layer material contains modified rubber powder. The modified rubber powder is prepared by sensitization, silver-ammonia solution treatment and acrylic acid-based tannic acid modification. The beneficial effects are as follows: the introduction of modified rubber powder into the support layer can improve the resilience of the support layer and thus improve the overall shock-absorbing property of the insole; the modification of the rubber powder can make the chelate on the surface of the rubber polymerize with the acrylic ester monomer after the addition of an initiator, thus ensuring that the mechanical strength of the support layer is not affected; and the powdering and modification of the foamed rubber sheet scraps can improve the utilization rate of raw materials and reduce production costs.

Description

Technical Field

[0001] This invention relates to the field of insole material technology, specifically to a shock-absorbing acrylic insole and its preparation method. Background Technology

[0002] Insoles are padding materials placed inside shoes to relieve pressure, provide comfort, and increase shoe stability. Shock-absorbing insoles are designed to reduce impact on the feet and joints. In addition to the advantages of ordinary insoles, they also reduce impact and alleviate sports injuries. EVA material, known for its excellent shock absorption, is commonly used in shock-absorbing insoles, but it has poor breathability, high compressibility, and is prone to deformation over long-term use. In comparison, polyurethane material has better durability, but it is heavier and more expensive. In recent years, shock-absorbing insoles have improved in comfort and functionality by changing their basic structure and using different materials in different functional areas. However, different structures require different molds, and different materials require different adhesives, keeping the cost of shock-absorbing insoles high. Acrylic materials have advantages such as low cost, wide application, high chemical resistance, and lightness, but as a shock-absorbing insole material, acrylic materials suffer from poor breathability and insufficient elasticity.

[0003] In summary, solving the above problems and manufacturing a shock-absorbing acrylic insole is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a shock-absorbing acrylic insole and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing a shock-absorbing acrylic insole includes the following steps:

[0007] Step 1: The foamed rubber sheet raw material is mixed, foamed, and cut to obtain foamed rubber sheets;

[0008] Step 2: Preparation of support layer emulsion: (1) Freeze-dry and pulverize the scraps of foamed rubber sheet to obtain rubber powder; (2) Sensitize the rubber powder with stannous chloride, treat with silver ammonia solution, and modify with acrylic tannic acid to obtain modified rubber powder; (3) Mix the acrylate monomer, emulsifier, and modified rubber powder evenly to obtain an oil phase; dissolve sodium chloride in deionized water to obtain an aqueous phase; mix the oil phase and aqueous phase, homogenize and emulsify to obtain a composite emulsion; (4) Mix the composite emulsion and initiator evenly at room temperature to obtain a support layer emulsion;

[0009] Step 3: Pour half of the support layer emulsion into the mold, lay non-woven fabric, and continue to add the other half of the support layer emulsion; steam curing to obtain the support layer; wherein the thickness of the support layer is 2-5 mm;

[0010] Step 4: Coat the surface of the foamed rubber sheet with a support layer emulsion, cover the support layer, with a coating amount of 80 grams per square meter, and hot roll at 110-120℃ to obtain a shock-absorbing acrylic insole.

[0011] In step 1, the foamed rubber sheet raw material includes the following components, by weight: 100 parts acrylate rubber, 2-3 parts accelerator, 30-50 parts plasticizer, 0.1-0.5 parts vulcanizing agent, 0.8-1.2 parts vulcanization accelerator, and 2-5 parts foaming agent.

[0012] Preferably, the accelerator includes, but is not limited to, one or more of stearic acid, zinc oxide, zinc stearate, sodium stearate, carbon black, and calcium stearate; the plasticizer includes, but is not limited to, one of dioctyl phthalate and diethyl phthalate; the vulcanizing agent includes, but is not limited to, sulfur, sulfur monochloride, and N,N-tetramethyldithiodisulfocarbonylamine; the vulcanization accelerator includes, but is not limited to, one of 2-mercaptobenzothiazole and zinc diethyldithiocarbamate; and the foaming agent includes, but is not limited to, one of ammonium bicarbonate and 4,4'-oxobisbenzenesulfonylhydrazine.

[0013] In step 1, the temperature during the mixing process is 80-100℃; the temperature during the foaming process is 100-200℃, the pressure is 8-12MPa, and the time is 8-12 minutes.

[0014] In step 2(1), the freeze-drying and pulverization is carried out using liquid nitrogen freeze-drying, and the particle size of the pulverized rubber powder is 0.05 to 0.2 mm.

[0015] In step 2(2), the specific process is as follows: the rubber powder after alkali washing is added to stannous chloride for sensitization for 1.5 to 2 hours; the sensitized rubber powder is added to silver ammonia solution for activation for 0.5 to 1 hour, filtered, and the obtained rubber powder is surface treated with formaldehyde as a reducing agent to obtain rubber powder A; tannic acid is added to deionized water, stirred evenly, and glutaraldehyde and hydroxyethyl acrylate are added dropwise at 50 to 70°C; the dropwise addition time is 1 to 2 hours, the reaction time is 5 to 6 hours, washed and dried to obtain chelating agent acrylic tannic acid; acrylic tannic acid is added to deionized water, rubber powder A is added, stirred and reacted for 20 to 40 minutes, filtered, and the powder is freeze-dried to obtain modified rubber powder; its function is that after the rubber powder is sensitized, activated and surface treated, it can form silver-containing substances on the surface, and the introduction of acrylic tannic acid can complex with the silver substances, thereby fixing the acrylic group on the surface of the rubber powder;

[0016] In a more optimized configuration, the mass ratio of tannic acid, glutaraldehyde, and hydroxyethyl acrylate is 340:(2-5):(3-5); the mass ratio of acrylic tannic acid, deionized water, and rubber powder A is (2-8):100:1.

[0017] In step 2(3), the composite emulsion includes the following components, by weight: 32-43 parts acrylate monomer, 1.5-2.5 parts emulsifier, 0.5-1.5 parts modified rubber powder, and 53-66 parts aqueous phase.

[0018] The acrylate monomers include hard acrylate monomers, soft acrylate monomers, and functional acrylate monomers, with a mass ratio of (6-10):(25-30):(1-3).

[0019] In a more optimized configuration, the acrylate hard monomer includes, but is not limited to, methyl methacrylate; the acrylate soft monomer includes, but is not limited to, one or more of ethyl acrylate and butyl acrylate; the acrylate functional monomer is a hydroxyl-containing acrylate; the emulsifier includes, but is not limited to, one of sorbitan stearate and sorbitan monooleate; and the aqueous phase includes, but is not limited to, a sodium chloride solution with a mass concentration of 2-5% and a deionized water solvent.

[0020] In step 2(4), the mass ratio of the composite emulsion to the initiator is (90-100):(0.1-1); the initiator includes, but is not limited to, sodium persulfate and potassium persulfate.

[0021] In step 3, the temperature of the steam curing is 90-120°C, and the time is 10-15 minutes.

[0022] The beneficial effects of this technical solution are:

[0023] (1) By introducing the powder of the scraps of foamed rubber sheet into the support layer of acrylic foam material, the shock absorption of the support layer can be improved, and the cost can be reduced, thus improving the overall economy of the insole.

[0024] (2) In the support layer material, ordinary rubber powder is dispersed and then wrapped by polymerized acrylate foam material. The intermolecular forces are small, which will affect the overall mechanical strength of the support layer. By modifying the rubber powder, the chelate formed on the surface of the rubber powder can polymerize with acrylate after the addition of an initiator to form a polymer, thereby improving the overall strength of the support layer.

[0025] In addition, by activating the rubber powder with silver ammonia solution, the silver on the surface of the rubber powder can improve the antibacterial properties of the insole. The carboxyl groups in the acrylic tannic acid can improve the overall coatability of the emulsion and the adhesion of the substrate after polymerization, making the connection structure between the three layers more stable. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The following examples contain the following raw materials: acrylic rubber, grade AR71, manufactured by Zeon Corporation; stearic acid (CAS No. 57-11-4); zinc oxide (CAS No. 1314-13-2); zinc stearate (CAS No. 57-05-1); sodium stearate (CAS No. 822-16-2); dioctyl phthalate (CAS No. 117-84-0); sulfur (CAS No. 7704-34-9); 2-mercaptobenzothiazole (CAS No. 149-30-4); 4,4'-oxobis(benzenesulfonyl hydrazine) (CAS No. 80-51-3); stannous chloride (CAS No. 10025-69-1); formaldehyde (CAS No. 5... 0-00-0); Tannic acid (CAS No. 1401-55-4); Glutaraldehyde (CAS No. 111-30-8); Hydroxyethyl acrylate (CAS No. 818-61-1); Methacrylate (CAS No. 922-67-8); Butyl acrylate (CAS No. 141-32-2); Methacrylic acid (CAS No. 79-41-4); Sorbitan stearate (CAS No. 1338-41-6); Sodium chloride (CAS No. 7647-14-5); Diethyl phthalate (CAS No. 84-66-2); Ethyl acrylate (CAS No. 140-88-5); Ammonium bicarbonate (CAS No. 1066-33-7).

[0028] Example 1: Step 1: Mix 100 parts of acrylate rubber, 1 part of stearic acid, 1 part of zinc oxide, 1 part of zinc stearate, and 0.5 parts of sodium stearate evenly, and knead at 90°C for 10 minutes; add 40 parts of dioctyl phthalate, 0.3 parts of sulfur, and 1 part of 2-mercaptobenzothiazole sequentially, and knead at 90°C for 5 minutes; add 3 parts of 4,4'-oxobis(benzenesulfonyl)hydrazine, and knead at 90°C for 10 minutes; transfer the kneaded mixture to a flat vulcanizing machine, heat to 150°C, pressurize to 10 MPa, and quickly open the mold after 10 minutes to obtain foamed rubber; cut the foamed rubber into suitable shapes to obtain foamed rubber sheets;

[0029] Step 2: Preparation of support layer emulsion: (1) The scraps of foamed rubber sheet were freeze-dried and pulverized with liquid nitrogen to obtain rubber powder; (2) The rubber powder after alkali washing was added to stannous chloride for sensitization for 2 hours; the sensitized rubber powder was added to silver ammonia solution for activation for 1 hour, filtered, and the obtained rubber powder was surface-treated with formaldehyde as a reducing agent to obtain rubber powder A; 340 parts of tannic acid were added to deionized water and stirred evenly. At 60°C, 2 parts of glutaraldehyde and 3 parts of hydroxyethyl acrylate were added dropwise; the dropwise addition time was 1-2 hours, the reaction time was 5-6 hours, and the mixture was washed and dried to obtain acrylic tannic acid; 3 parts of acrylic tannic acid were added to 100 parts of deionized water, 1 part of rubber powder A was added, the mixture was stirred and reacted for 30 minutes, filtered, and the powder was obtained. (3) Preheat the oil phase mixing pot to 50°C, add 8.8 parts of methyl methacrylate, 30 parts of butyl acrylate, 1.2 parts of methacrylic acid, 2 parts of sorbitan stearate and 0.5 parts of modified rubber powder in sequence and stir at a stirring speed of 600 rpm until uniform oil phase is obtained; prepare a sodium chloride solution with a mass concentration of 3% as the aqueous phase, add 58 parts of the aqueous phase solution to the homogenizer and heat to 80°C to start stirring, gradually add the oil phase at a speed of 1200 rpm, after the addition is completed, homogenize and emulsify for 8 minutes, at which time the homogenization speed is controlled at 9000 rpm; add 0.5 parts of sodium persulfate and start stirring at a stirring speed of 1200 rpm, after uniform mixing, the support layer emulsion is obtained;

[0030] Step 3: Pour half of the support layer emulsion into the mold, lay non-woven fabric, and continue to add the other half of the support layer emulsion; transfer the mold to a high-pressure steam oven, control the temperature at 100℃, and steam solidify for 10 minutes to obtain the support layer with a thickness of 3 mm.

[0031] Step 4: Coat the surface of the foamed rubber sheet with a support layer emulsion, cover the support layer, with a coating amount of 80 grams per square meter, and hot roll at 120°C to obtain a shock-absorbing acrylic insole.

[0032] Example 2: Step 1: Mix 100 parts of acrylate rubber, 1 part of stearic acid, 1 part of zinc oxide, 1 part of zinc stearate, and 0.5 parts of sodium stearate evenly, and knead at 90°C for 10 minutes; add 40 parts of dioctyl phthalate, 0.3 parts of sulfur, and 1 part of 2-mercaptobenzothiazole sequentially, and knead at 90°C for 5 minutes; add 3 parts of 4,4'-oxobis(benzenesulfonyl)hydrazine, and knead at 90°C for 10 minutes; transfer the kneaded mixture to a flat vulcanizing machine, heat to 150°C, pressurize to 10 MPa, and quickly open the mold after 10 minutes to obtain foamed rubber; cut the foamed rubber into suitable shapes to obtain foamed rubber sheets;

[0033] Step 2: Preparation of support layer emulsion: (1) The scraps of foamed rubber sheet were freeze-dried and pulverized with liquid nitrogen to obtain rubber powder; (2) The rubber powder after alkali washing was added to stannous chloride for sensitization for 2 hours; the sensitized rubber powder was added to silver ammonia solution for activation for 1 hour, filtered, and the obtained rubber powder was surface-treated with formaldehyde as a reducing agent to obtain rubber powder A; 340 parts of tannic acid were added to deionized water and stirred evenly. At 60°C, 2 parts of glutaraldehyde and 3 parts of hydroxyethyl acrylate were added dropwise; the dropwise addition time was 1-2 hours, the reaction time was 5-6 hours, and the mixture was washed and dried to obtain acrylic tannic acid; 3 parts of acrylic tannic acid were added to 100 parts of deionized water, 1 part of rubber powder A was added, the mixture was stirred and reacted for 30 minutes, filtered, and the powder was obtained. (3) Preheat the oil phase mixing pot to 50°C, add 8.8 parts of methyl methacrylate, 30 parts of butyl acrylate, 1.2 parts of methacrylic acid, 2 parts of sorbitan stearate and 1 part of modified rubber powder in sequence and stir at a stirring speed of 600 rpm until uniform oil phase is obtained; prepare a sodium chloride solution with a mass concentration of 3% as the aqueous phase, add 58 parts of the aqueous phase solution to the homogenizer and heat to 80°C to start stirring, gradually add the oil phase at a speed of 1200 rpm, after the addition is completed, homogenize and emulsify for 8 minutes, at which time the homogenization speed is controlled at 9000 rpm; add 0.5 parts of sodium persulfate and start stirring at a stirring speed of 1200 rpm, after uniform mixing, the support layer emulsion is obtained;

[0034] Step 3: Pour half of the support layer emulsion into the mold, lay non-woven fabric, and continue to add the other half of the support layer emulsion; transfer the mold to a high-pressure steam oven, control the temperature at 100℃, and steam solidify for 10 minutes to obtain the support layer with a thickness of 3 mm.

[0035] Step 4: Coat the surface of the foamed rubber sheet with a support layer emulsion, cover the support layer, with a coating amount of 80 grams per square meter, and hot roll at 120°C to obtain a shock-absorbing acrylic insole.

[0036] Example 3: Step 1: Mix 100 parts of acrylate rubber, 1 part of stearic acid, 1 part of zinc oxide, 1 part of zinc stearate, and 0.5 parts of sodium stearate evenly, and knead at 90°C for 10 minutes; add 40 parts of dioctyl phthalate, 0.3 parts of sulfur, and 1 part of 2-mercaptobenzothiazole sequentially, and knead at 90°C for 5 minutes; add 3 parts of 4,4'-oxobis(benzenesulfonyl)hydrazine, and knead at 90°C for 10 minutes; transfer the kneaded mixture to a flat vulcanizing machine, heat to 150°C, pressurize to 10 MPa, and quickly open the mold after 10 minutes to obtain foamed rubber; cut the foamed rubber into suitable shapes to obtain foamed rubber sheets;

[0037] Step 2: Preparation of support layer emulsion: (1) The scraps of foamed rubber sheet were freeze-dried and pulverized with liquid nitrogen to obtain rubber powder; (2) The rubber powder after alkali washing was added to stannous chloride for sensitization for 2 hours; the sensitized rubber powder was added to silver ammonia solution for activation for 1 hour, filtered, and the obtained rubber powder was surface-treated with formaldehyde as a reducing agent to obtain rubber powder A; 340 parts of tannic acid were added to deionized water and stirred evenly. At 60°C, 2 parts of glutaraldehyde and 3 parts of hydroxyethyl acrylate were added dropwise; the dropwise addition time was 1-2 hours, the reaction time was 5-6 hours, and the mixture was washed and dried to obtain acrylic tannic acid; 3 parts of acrylic tannic acid were added to 100 parts of deionized water, 1 part of rubber powder A was added, the mixture was stirred and reacted for 30 minutes, filtered, and the powder was obtained. (3) Preheat the oil phase mixing pot to 50°C, add 8.8 parts of methyl methacrylate, 30 parts of butyl acrylate, 1.2 parts of methacrylic acid, 2 parts of sorbitan stearate and 1.5 parts of modified rubber powder in sequence and stir at a stirring speed of 600 rpm until uniform oil phase is obtained; prepare a sodium chloride solution with a mass concentration of 3% as the aqueous phase, add 58 parts of the aqueous phase solution to the homogenizer and heat to 80°C to start stirring, gradually add the oil phase at a speed of 1200 rpm, after the addition is completed, homogenize and emulsify for 8 minutes, at which time the homogenization speed is controlled at 9000 rpm; add 0.5 parts of sodium persulfate and start stirring at a stirring speed of 1200 rpm, after uniform mixing, the support layer emulsion is obtained;

[0038] Step 3: Pour half of the support layer emulsion into the mold, lay non-woven fabric, and continue to add the other half of the support layer emulsion; transfer the mold to a high-pressure steam oven, control the temperature at 100℃, and steam solidify for 10 minutes to obtain the support layer with a thickness of 3 mm.

[0039] Step 4: Coat the surface of the foamed rubber sheet with a support layer emulsion, cover the support layer, with a coating amount of 80 grams per square meter, and hot roll at 120°C to obtain a shock-absorbing acrylic insole.

[0040] Example 4: The 4,4'-oxobis(benzenesulfonylhydrazine) in step 1 was replaced with ammonium bicarbonate, and the butyl acrylate in step 2 (3) was replaced with ethyl acrylate. The rest was the same as in Example 2.

[0041] Comparative Example 1: Step 1: Mix 100 parts of acrylic rubber, 1 part of stearic acid, 1 part of zinc oxide, 1 part of zinc stearate, and 0.5 parts of sodium stearate evenly, and knead at 90°C for 10 minutes; add 40 parts of dioctyl phthalate, 0.3 parts of sulfur, and 1 part of 2-mercaptobenzothiazole sequentially, and knead at 90°C for 5 minutes; add 3 parts of 4,4'-oxobis(benzenesulfonyl)hydrazine, and knead at 90°C for 10 minutes; transfer the kneaded mixture to a flat vulcanizing machine, heat to 150°C, pressurize to 10 MPa, and quickly open the mold after 10 minutes to obtain foamed rubber; cut the foamed rubber into suitable shapes to obtain foamed rubber sheets;

[0042] Step 2: Preparation of the support layer emulsion: Preheat the oil phase mixing pot to 50°C, then add 8.8 parts of methyl methacrylate, 30 parts of butyl acrylate, 1.2 parts of methacrylic acid, and 2 parts of sorbitan stearate sequentially and stir at 600 rpm until homogeneous to obtain the oil phase; prepare a 3% sodium chloride solution as the aqueous phase, add 58 parts of the aqueous phase solution to a homogenizer and heat to 80°C, then start stirring. Gradually add the oil phase at 1200 rpm. After the addition is complete, homogenize and emulsify for 8 minutes, at which time the homogenizer speed is controlled at 9000 rpm; add 0.5 parts of sodium persulfate and start stirring at 1200 rpm until homogeneous to obtain the support layer emulsion;

[0043] Step 3: Pour half of the support layer emulsion into the mold, lay non-woven fabric, and continue to add the other half of the support layer emulsion; transfer the mold to a high-pressure steam oven, control the temperature at 100℃, and steam solidify for 10 minutes to obtain the support layer with a thickness of 3 mm.

[0044] Step 4: Coat the surface of the foamed rubber sheet with a support layer emulsion, cover the support layer, with a coating amount of 80 grams per square meter, and hot roll at 120°C to obtain a shock-absorbing acrylic insole.

[0045] Comparative Example 2: Step 1: Mix 100 parts of acrylic rubber, 1 part of stearic acid, 1 part of zinc oxide, 1 part of zinc stearate, and 0.5 parts of sodium stearate evenly, and knead at 90°C for 10 minutes; add 40 parts of dioctyl phthalate, 0.3 parts of sulfur, and 1 part of 2-mercaptobenzothiazole sequentially, and knead at 90°C for 5 minutes; add 3 parts of 4,4'-oxobis(benzenesulfonyl)hydrazine, and knead at 90°C for 10 minutes; transfer the kneaded mixture to a flat vulcanizing machine, heat to 150°C, pressurize to 10 MPa, and quickly open the mold after 10 minutes to obtain foamed rubber; cut the foamed rubber into suitable shapes to obtain foamed rubber sheets;

[0046] Step 2: Preparation of support layer emulsion: (1) The scraps of foamed rubber sheet were freeze-dried and pulverized with liquid nitrogen to obtain rubber powder; (2) The oil phase mixing pot was preheated to 50°C, and 8.8 parts of methyl methacrylate, 30 parts of butyl acrylate, 1.2 parts of methacrylic acid, 2 parts of sorbitan stearate and 1 part of rubber powder were added in sequence and stirred at a stirring speed of 600 rpm until uniform oil phase was obtained; a 3% sodium chloride solution was prepared as the aqueous phase, and 58 parts of the aqueous phase solution were added to the homogenizer and heated to 80°C and stirred. The oil phase was gradually dripped at a speed of 1200 rpm. After the addition was completed, the homogenizer was homogenized for 8 minutes at a speed of 9000 rpm; 0.5 parts of sodium persulfate were added and stirring was started at a stirring speed of 1200 rpm. After uniform mixing, the support layer emulsion was obtained;

[0047] Step 3: Pour half of the support layer emulsion into the mold, lay non-woven fabric, and continue to add the other half of the support layer emulsion; transfer the mold to a high-pressure steam oven, control the temperature at 100℃, and steam solidify for 10 minutes to obtain the support layer with a thickness of 3 mm.

[0048] Step 4: Coat the surface of the foamed rubber sheet with a support layer emulsion, cover the support layer, with a coating amount of 80 grams per square meter, and hot roll at 120°C to obtain a shock-absorbing acrylic insole.

[0049] Comparative Example 3: Example 2: Step 1: Mix 100 parts of acrylate rubber, 1 part of stearic acid, 1 part of zinc oxide, 1 part of zinc stearate, and 0.5 parts of sodium stearate evenly, and knead at 90°C for 10 minutes; add 40 parts of dioctyl phthalate, 0.3 parts of sulfur, and 1 part of 2-mercaptobenzothiazole in sequence, and knead at 90°C for 5 minutes; add 3 parts of 4,4'-oxobis(benzenesulfonyl)hydrazine and knead at 90°C for 10 minutes; transfer the kneaded mixture to a flat vulcanizing machine, heat to 150°C, pressurize to 10 MPa, and quickly open the mold after 10 minutes to obtain foamed rubber; cut the foamed rubber into a suitable shape to obtain foamed rubber sheets;

[0050] Step 2: Preparation of support layer emulsion: (1) The scraps of foamed rubber sheet were freeze-dried and pulverized with liquid nitrogen to obtain rubber powder; (2) The rubber powder after alkali washing was added to stannous chloride for sensitization for 2 hours; the sensitized rubber powder was added to silver ammonia solution for activation for 1 hour, filtered, and the obtained rubber powder was surface-treated with formaldehyde as a reducing agent to obtain rubber powder A; (3) The oil phase mixing pot was preheated to 50°C, and 8.8 parts of methyl methacrylate, 30 parts of butyl acrylate, 1.2 parts of methacrylic acid, and 2 parts of sorbitan stearate were added. One part of rubber powder A was added sequentially and stirred at a speed of 600 rpm until a uniform oil phase was obtained. A 3% sodium chloride solution was prepared as the aqueous phase. 58 parts of the aqueous phase solution were added to a homogenizing emulsifier and heated to 80°C. Stirring was started, and the oil phase was gradually added dropwise at a speed of 1200 rpm. After the addition was completed, homogenization and emulsification were carried out for 8 minutes, during which the homogenization speed was controlled at 9000 rpm. 0.5 parts of sodium persulfate were added and stirring was started at a speed of 1200 rpm. After mixing evenly, the support layer emulsion was obtained.

[0051] Step 3: Pour half of the support layer emulsion into the mold, lay non-woven fabric, and continue to add the other half of the support layer emulsion; transfer the mold to a high-pressure steam oven, control the temperature at 100℃, and steam solidify for 10 minutes to obtain the support layer with a thickness of 3 mm.

[0052] Step 4: Coat the surface of the foamed rubber sheet with a support layer emulsion, cover the support layer, with a coating amount of 80 grams per square meter, and hot roll at 120°C to obtain a shock-absorbing acrylic insole.

[0053] Comparative Example 4: The active modified rubber powder in step 2 (3) was changed from 1 part to 3 parts, and the rest was the same as in Example 2.

[0054] Experiment: The longitudinal tensile strength of the support layers prepared in Examples 1-5 and Comparative Examples 1-2 was measured at 25℃. The shock-absorbing acrylic insoles prepared in Examples 1-5 and Comparative Examples 1-2 were used to determine their overall resilience according to ASTM D2632-2015 "Standard Test Methods for Rubber Properties - Determination of Rubber Elasticity by Vertical Rebound Method". The specific experimental data are as follows:

[0055] Longitudinal fracture strength at 25℃ (N / 25mm) 18.3 18.9 18.0 18.5 17.6 16.3 16.8 15.6 Overall rebound rate (%) 78 82 83 81 64 72 74 78

[0056] Analysis of the experimental data shows that, according to Examples 1-4, the insole's resilience is superior with increasing amounts of modified rubber powder. Combined with the longitudinal tensile strength of the support layer, Example 2 shows the best performance. Examples 2 and Comparative Example 1 demonstrate that the introduction of rubber powder can improve the resilience and shock absorption of the support layer. Examples 2 and Comparative Examples 1-3 indicate that modifying the rubber powder and copolymerizing it with acrylate materials during the emulsion polymerization of the support layer can improve shock absorption while ensuring the overall mechanical strength of the support layer remains unaffected. Examples 2 and Comparative Example 4 show that excessive amounts of modified rubber powder can affect the mechanical strength of the support layer material; therefore, the amount of modified rubber powder added needs to be controlled.

[0057] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a shock-absorbing acrylic insole, characterized in that: Includes the following steps: Step 1: The foamed rubber sheet raw material is mixed, foamed, and cut to obtain foamed rubber sheets; Step 2: Preparation of support layer emulsion: (1) Freeze-dry and pulverize the scraps of foamed rubber sheet to obtain rubber powder; (2) Sensitize the rubber powder with stannous chloride, treat with silver ammonia solution, and modify with acrylic tannic acid to obtain modified rubber powder; (3) Mix the acrylate monomer, emulsifier, and modified rubber powder evenly to obtain an oil phase; dissolve sodium chloride in deionized water to obtain an aqueous phase; mix the oil phase and aqueous phase, homogenize and emulsify to obtain a composite emulsion; (4) Mix the composite emulsion and initiator evenly at room temperature to obtain a support layer emulsion; Step 3: Pour half of the support layer emulsion into the mold, lay down the non-woven fabric, and continue to add the other half of the support layer emulsion; steam curing to obtain the support layer; Step 4: Coat the surface of the foamed rubber sheet with a support layer emulsion, cover the support layer, and hot roll at 110-120℃ to obtain a shock-absorbing acrylic insole.

2. The method for preparing a shock-absorbing acrylic insole according to claim 1, characterized in that: In step 1, the foamed rubber sheet raw material includes the following components, by weight: 100 parts acrylate rubber, 2-5 parts accelerator, 30-50 parts plasticizer, 0.1-0.5 parts vulcanizing agent, 0.8-1.2 parts vulcanization accelerator, and 2-5 parts foaming agent.

3. The method for preparing a shock-absorbing acrylic insole according to claim 1, characterized in that: In step 1, the temperature during the mixing process is 80-100℃; the temperature during the foaming process is 100-200℃, the pressure is 8-12MPa, and the time is 8-12 minutes.

4. The method for preparing a shock-absorbing acrylic insole according to claim 1, characterized in that: In step 2(2), the specific process is as follows: the rubber powder after alkali washing is added to stannous chloride for sensitization for 1.5 to 2 hours; the sensitized rubber powder is added to silver ammonia solution for activation for 0.5 to 1 hour, filtered, and the obtained rubber powder is surface treated with formaldehyde as a reducing agent to obtain rubber powder A; tannic acid is added to deionized water, stirred evenly, and glutaraldehyde and hydroxyethyl acrylate are added dropwise at 50 to 70°C; the dropwise addition time is 1 to 2 hours, the reaction time is 5 to 6 hours, washed and dried to obtain chelating agent acrylic tannic acid; acrylic tannic acid is added to deionized water, rubber powder A is added, the reaction is stirred for 20 to 40 minutes, filtered, and the powder is freeze-dried to obtain modified rubber powder.

5. The method for preparing a shock-absorbing acrylic insole according to claim 4, characterized in that: The mass ratio of tannic acid, glutaraldehyde, and hydroxyethyl acrylate is 340:(2-5):(3-5); the mass ratio of acrylic tannic acid, deionized water, and rubber powder A is (2-8):100:

1.

6. The method for preparing a shock-absorbing acrylic insole according to claim 1, characterized in that: In step 2(3), the composite emulsion comprises the following components, by weight: 32-43 parts acrylate monomer, 1.5-2.5 parts emulsifier, 0.5-1.5 parts modified rubber powder, and 53-66 parts aqueous phase.

7. The method for preparing a shock-absorbing acrylic insole according to claim 1, characterized in that: In step 2 (3), the acrylate monomers include hard acrylate monomers, soft acrylate monomers, and functional acrylate monomers, with a mass ratio of (6-10):(25-30):(1-3).

8. The method for preparing a shock-absorbing acrylic insole according to claim 1, characterized in that: In step 3, the temperature of the steam curing is 90-120°C, and the time is 10-15 minutes.

9. The shock-absorbing acrylic insole prepared by the method of preparing a shock-absorbing acrylic insole according to any one of claims 1 to 8.