A back pad material containing biocrystals and a method for preparing the same

Abstract

The application provides a back pad material containing biological crystals and a preparation method thereof and belongs to the technical field of polyurethane foams. Polyether polyol and polyester polyol are mixed, modified chain extender, triethylenediamine, a catalyst, a foam stabilizer and water are added, stirring and mixing are uniformly conducted, isocyanate is added, the mixture is poured into a mold, heating and standing are conducted for foaming and solidification, demolding is conducted, a foamed polyurethane is obtained, the foamed polyurethane is immersed into a sodium acetate buffer solution containing dopamine and sodium periodate, standing is conducted, the foamed polyurethane is taken out, the foamed polyurethane is immersed into a copper salt solution again, standing is conducted under ultraviolet light, the foamed polyurethane is taken out, washing and drying are conducted, and the back pad material containing biological crystals is prepared. The back pad material containing biological crystals has excellent rebound supporting property, good dispersion stability, persistent broad-spectrum antibacterial property and far infrared health care function.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam technology, specifically to a backing material containing biocrystals and its preparation method. Background Technology

[0002] Polyurethane (PU) flexible foam, due to its low density, high specific strength, and good dimensional stability, possesses excellent resilience, sound absorption, breathability, and thermal insulation properties. It is widely used in mattresses, vehicle seats, clothing padding, and various soft laminated composite padding materials. Its preparation method involves foaming polyether polyols and isocyanates through a series of chemical reactions. Polyurethane flexible foam accounts for approximately 50% of the total polyurethane product output, and its application scope continues to expand. However, flexible polyurethane foam materials have certain drawbacks that affect the end-user experience, as follows: 1. In order to ensure a soft seating experience, traditional polyurethane foam often sacrifices support, which can easily lead to "collapse" after long-term use. If the density and hardness are increased, the resilience will decrease, resulting in a "stiff" feeling. Therefore, it is difficult to balance resilience and support.

[0003] 2. The direct addition of conventional inorganic fillers such as calcium carbonate and talc has poor compatibility with the polyurethane matrix, and is prone to agglomeration, resulting in uneven cell structure, decreased mechanical properties, and even stress concentration points, leading to performance degradation.

[0004] 3. Due to the porosity and hygroscopicity of polyurethane flexible foam, its products are easily contaminated with sweat and various stains, causing bacterial growth, resulting in material performance loss, and posing a threat to the environment and human health.

[0005] 4. Existing back pads only have physical cushioning function and lack health functions such as temperature and humidity regulation, antibacterial and far-infrared, which cannot meet the needs of consumption upgrading.

[0006] Therefore, developing flexible polyurethane products with suitable resilience and support, balanced mechanical properties, and antibacterial and far-infrared properties can not only meet user needs but also enhance the market competitiveness of enterprises. Summary of the Invention

[0007] The purpose of this invention is to propose a back pad material containing biocrystals and its preparation method. By designing a hyperbranched quaternary ammonium salt chain extender to chemically modify the surface of biocrystal powder and participate in the polyurethane foaming reaction, combined with a polydopamine self-polymerization coating and ultraviolet light-induced copper ion chelation reduction technology, a back pad material containing biocrystals with excellent resilience and support, good dispersion stability, long-lasting broad-spectrum antibacterial properties and far-infrared health care functions is obtained.

[0008] The technical solution of this invention is implemented as follows: This invention provides a method for preparing a back pad material containing biocrystals, comprising the following steps: S1. Provide a quaternary ammonium salt chain extender, prepare a hyperbranched chain extender with a silane coupling agent, and then react it with biocrystal powder to obtain a modified chain extender; S2. Mix polyether polyol and polyester polyol, add chain extender, triethylenediamine, catalyst, foam stabilizer and water, stir and mix evenly to obtain white material. Add black material to white material, stir and mix evenly, pour into mold, heat and let stand to foam and cure, demold to obtain foamed polyurethane; S3. Add dopamine and sodium periodate to sodium acetate buffer solution, immerse polyurethane foam in the solution, let stand, take out, wash, and obtain coated polyurethane foam. S4. Immerse the coated polyurethane foam in a copper salt solution, let it stand under ultraviolet light, remove it, wash it, and dry it to obtain a back pad material containing biocrystals.

[0009] As a further improvement of the present invention, the preparation method of the quaternary ammonium salt chain extender is as follows: methyl bromoacetate and N,N-dimethylalkylamine are reacted to obtain N,N-dimethylalkylN-acetate quaternary ammonium salt, which is then reacted with 3-amino-1,2-propanediol to obtain the quaternary ammonium salt chain extender.

[0010] As a further improvement of the present invention, the molar ratio of methyl bromoacetate to N,N-dimethylalkylamine is 1.2-1.7:1, the reaction temperature is 40-70℃, and the time is 20-28h; the molar ratio of N,N-dimethylalkylN-acetate quaternary ammonium salt to 3-amino-1,2-propanediol is 1:1.5-2, the melting reaction temperature is 75-85℃, and the time is 10-15h.

[0011] As a further improvement of the present invention, the N,N-dimethylalkylamine is selected from at least one of N,N-dimethyltetradecylamine, N,N-dimethyldodecylamine, N,N-dimethylpentadecanamine, and N,N-dimethyltridecylamine.

[0012] As a further improvement to the present invention, the reaction in step S1 is specifically as follows: S101. A hyperbranched chain extender is prepared by mixing a quaternary ammonium salt chain extender and a silane coupling agent KH560 and heating them together. S102. Mix tourmaline powder, jade powder, and opal powder, grind them, and sieve them to obtain bio-crystal powder; S103. Add the hyperbranched chain extender to an ethanol-water solution, adjust the pH value, perform a hydrolysis reaction, add biocrystal powder, heat and sonicate, filter, wash, dry, grind, and sieve to obtain the modified chain extender.

[0013] As a further improvement of the present invention, in step S101, the mass ratio of the quaternary ammonium salt chain extender to the silane coupling agent KH560 is 0.5-1:1-2, the heating temperature is 110-120℃, and the time is 1-2h; in step S102, the mass ratio of the tourmaline powder, jade powder, and opal powder is 3-5:5-10:1-4; in step S103, the concentration of the ethanol aqueous solution is 90-95wt%, the pH value is adjusted to 3.5-4.5, the hydrolysis reaction time is 4-8h, the mass ratio of the hyperbranched chain extender to the biocrystal powder is 1:2-4, and the heating and ultrasonic reaction temperature is 75-85℃, and the time is 2-4h.

[0014] As a further improvement of the present invention, in step S2, the mass ratio of polyether polyol, polyester polyol, modified chain extender, triethylenediamine, catalyst, foam stabilizer and water is 7-8:2-3:1-2:0.01-0.03:0.01-0.02:0.1-0.15:0.2-0.4, the mass ratio of white material to black material is 10-11:4.5-5.5, the black material is diphenylmethane diisocyanate, the catalyst is an organotin catalyst, the foam stabilizer is an organosilicon foam stabilizer, and the heating and settling temperature is 45-55℃, and the time is 20-40 min.

[0015] As a further improvement of the present invention, the mass ratio of dopamine to sodium periodate in step S3 is 1-1.5:2-3, and the pH value of the sodium acetate buffer solution is 5-6.

[0016] As a further improvement of the present invention, the concentration of the copper salt solution in step S4 is 0.05-0.15 mol / L, the copper salt is selected from at least one of copper chloride, copper sulfate, and copper nitrate, the wavelength of the ultraviolet light is 365 nm, and the standing time is 20-40 min.

[0017] The present invention further protects a back pad material containing biocrystals prepared by the above-described preparation method.

[0018] The present invention has the following beneficial effects: 1. This invention modifies biocrystal powder with hyperbranched quaternary ammonium salt chain extenders, introducing it into the polyurethane molecular network through chemical bonding. The biocrystals, as rigid inorganic reinforcing phases, are uniformly dispersed in the soft foam matrix. Under stress, they can effectively disperse stress and suppress large cell distortion, thereby improving the compressive strength and support of the foam without significantly increasing the density. At the same time, the appropriate crosslinking points introduced by the hyperbranched structure and the synergistic soft segment design of polyether / polyester polyol ensure that the foam molecular chains still have sufficient flexible recovery ability, giving the product both excellent resilience and support.

[0019] 2. This invention utilizes hyperbranched chain extenders to perform surface grafting modification on biocrystal powder: hyperbranched molecules have a three-dimensional dendritic structure, and their numerous terminal groups (hydroxyl, amino, etc.) can form hydrogen bonds or covalent bonds with the polyurethane matrix, while quaternary ammonium salt cationic groups prevent particle aggregation through electrostatic repulsion, and siloxane chains formed by the hydrolysis of silane coupling agents are firmly anchored to the surface of biocrystals, enabling the biocrystals to be uniformly dispersed in the polyol system, thus avoiding the problems of uneven pore structure and decreased mechanical properties.

[0020] 3. This invention constructs a dual antibacterial system: quaternary ammonium salt contact sterilization and copper ion leaching sterilization. Specifically, the long-chain alkyl quaternary ammonium salt groups in the hyperbranched chain extender molecule carry a positive charge, enabling them to adsorb and penetrate the bacterial cell membrane, disrupting the membrane structure and causing intracellular leakage, thus achieving contact sterilization. The polydopamine coating chelates and immobilizes copper ions through catechol groups, and under ultraviolet light assistance, partially absorbs copper ions. 2+ Reduced to Cu + / Cu 0 Nanoparticles continuously release copper ions with strong oxidizing properties, disrupting bacterial enzyme systems. These two mechanisms work synergistically to give the backing material broad-spectrum and long-lasting antibacterial properties, effectively inhibiting the growth of common pathogenic bacteria such as Staphylococcus aureus and Escherichia coli.

[0021] 4. The bio-crystals selected in this invention, such as tourmaline, jade, and opal, possess natural far-infrared emission and negative ion release functions. Through chemical modification, these crystals are stably embedded in polyurethane foam, allowing the back pad material to continuously emit far-infrared rays at room temperature, promoting local microcirculation; simultaneously, it releases negative ions, improving the local microenvironment. This upgrades the back pad from a simple physical cushioning material into a health product with added health benefits, meeting the demands of consumer upgrading.

[0022] 5. The polydopamine coating uniformly coats the surface of the polyurethane foam through a self-polymerization reaction. Its abundant catechol and amino groups form strong hydrogen bonds and π-π stacking interactions with the polyurethane matrix, enhancing the coating adhesion. On the other hand, it acts as a "molecular glue" and reducing agent, chelating copper salts and reducing them in situ under ultraviolet light to generate copper-based nanoparticles. This allows copper ions to be firmly anchored to the material surface rather than simply physically adsorbed, preventing the rapid loss of antibacterial components during use and significantly improving the durability of the function. Furthermore, polydopamine can effectively convert photon energy into heat energy, making it a good photothermal agent and improving the photothermal antibacterial effect. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The infrared spectrum of the back pad material containing biocrystals prepared in Example 1 is shown.

[0025] Figure 2 SEM image (200 μm) of the back pad material containing biocrystals prepared in Example 1.

[0026] Figure 3 SEM image (10 μm) of the back pad material containing biocrystals prepared in Example 1. Detailed Implementation

[0027] 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.

[0028] Example 1

[0029] This embodiment provides a method for preparing a back pad material containing biocrystals, including the following steps: S1. 0.15 mol methyl bromoacetate and 0.1 mol N,N-dimethyldodecylamine were added to 100 mL tetrahydrofuran, heated to 50 °C, and stirred for 24 h to obtain N,N-dimethyldodecyl N-acetate quaternary ammonium salt. 0.1 mol N,N-dimethyldodecyl N-acetate quaternary ammonium salt and 0.17 mol 3-amino-1,2-propanediol were heated to 80 °C and melted for 10 h. Hydrochloric acid was added to adjust the pH to acidic during the reaction. The mixture was extracted with dichloromethane, the organic phase was separated, dried over anhydrous magnesium sulfate, filtered, and dichloromethane was removed by rotary evaporation. The mixture was then dried under vacuum to obtain the quaternary ammonium salt chain extender. The synthesis route is as follows:

[0030] The ESI-MS calculated value of N,N-dimethyldodecyl N-acetic acid methyl ester quaternary ammonium salt is: C 17 H 36 NO2 + [M] + 286.27, measured value: 286.3. NMR results:1 H NMR (300MHz, CDCl3) δ4.2 (s, 2H), 3.69 (s, 3H), 2.92 (t, 2H), 2.85 (s, 6H), 1.26-1.32 (m, 20H), 0.94 (t, 3H).

[0031] ESI-MS calculated value of quaternary ammonium salt chain extender: C 19 H 41 N2O3 + [M] + 345.31, measured value: 345.3. NMR results: 1 H NMR (300MHz, CDCl3) δ8.1 (br, 1H), 4.17 (s, 2H), 3.94 (m, 1H), 3.85 (d, 2H), 3.59 (d , 2H), 3.3-3.32 (m, 8H), 2.2 (br, 2H), 1.75 (m, 2H), 1.27-1.3 (m, 18H), 0.97 (t, 3H).

[0032] S2. Mix 5g of quaternary ammonium salt chain extender and 10g of silane coupling agent KH560, heat to 110℃, stir and react for 2h to obtain hyperbranched chain extender. S3. Mix 15g tourmaline powder, 25g jade powder, and 5g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S4. Add 10g of hyperbranched chain extender to 95wt% ethanol aqueous solution, adjust the pH value to 3.5-4.5 with acetic acid, hydrolyze for 4h, add 20g of biocrystal powder, heat to 75℃, sonicate at 200W for 4h, filter, wash, dry, grind, and pass through a 3000-mesh sieve to obtain the modified chain extender. S5. Mix 70g of polyether polyol 330 (molecular weight 4800, industrial grade) and 30g of polyester polyol 204 (molecular weight 3000, industrial grade), add 10g of modified chain extender, 0.1g of triethylenediamine, 0.1g of dibutyltin dilaurate, 1g of silicone foaming agent and 2g of water, stir at 1000r / min for 2min to obtain white material. Take 100g of white material and add 45g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S6. Add 1g of dopamine and 2g of sodium periodate to 500mL of sodium acetate buffer solution with a pH of 5-6. Immerse the foamed polyurethane obtained in step S5 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain the coated foamed polyurethane. S7. Immerse the coated polyurethane foam obtained in step S6 into 500 mL of 0.05 mol / L copper chloride solution, let it stand under 365 nm ultraviolet light for 20 min, take it out, ultrasonically wash it with deionized water for 10 min, and place it in a vacuum drying oven at 60 °C for 5 h to obtain a back pad material containing biocrystals. Figure 1 The infrared spectrum of the back pad material containing biocrystals is shown in the figure. As can be seen from the figure, at 3380 cm⁻¹... -1 The peak at 2920 cm⁻¹ is a characteristic peak for NH / OH. -1 2850cm -1 The peak at 1720 cm⁻¹ represents the CH stretching vibration. -1 The peak at 1600 cm⁻¹ is the -C=O stretching vibration peak, the peak at 1650 cm⁻¹ is the characteristic peak of the amide I band and C=N, and the peak at 1600 cm⁻¹ is the characteristic peak of the C=N band. -1 and 1580cm -1 The peak at 1530 cm⁻¹ is the vibrational peak of the aromatic ring skeleton. -1 The location is the amide II band, 1450 cm. -1 The peak at 1100-1000 cm⁻¹ represents the CH bending vibration peak. -1 The peak at 800-600 cm⁻¹ represents the stretching vibration peak of COC / Si-O-Si / Si-OM. -1 The peak at this location represents a biocrystalline phase mineral.

[0033] Figure 2 The image shows a SEM image of the biocrystal-containing back pad material. As can be seen from the image, the obtained material has a porous structure. Figure 3 The image shows a magnified SEM image of the biocrystal-containing back pad material. As can be seen from the image, there are many granular structures on it.

[0034] Example 2

[0035] This embodiment provides a method for preparing a back pad material containing biocrystals, including the following steps: S1. A quaternary ammonium salt chain extender was prepared according to the method of Example 1; S2. Mix 10g of quaternary ammonium salt chain extender and 20g of silane coupling agent KH560, heat to 120℃, stir and react for 1h to obtain hyperbranched chain extender; S3. Mix 25g tourmaline powder, 50g jade powder, and 20g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S4. Add 10g of hyperbranched chain extender to 95wt% ethanol aqueous solution, adjust the pH to 3.5-4.5 with acetic acid, hydrolyze for 8h, add 40g of biocrystal powder, heat to 85℃, sonicate at 200W for 2h, filter, wash, dry, grind, and pass through a 3000-mesh sieve to obtain the modified chain extender. S5. Mix 80g of polyether polyol 330 (molecular weight 4800, industrial grade) and 20g of polyester polyol 204 (molecular weight 3000, industrial grade), add 20g of modified chain extender, 0.3g of triethylenediamine, 0.2g of dibutyltin dilaurate, 1.5g of silicone foaming agent and 4g of water, stir at 1000r / min for 2min to obtain white material. Take 110g of white material and add 55g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S6. Add 1.5g dopamine and 3g sodium periodate to 500mL of sodium acetate buffer solution with pH 5-6, immerse the foamed polyurethane obtained in step S5 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain coated foamed polyurethane. S7. Immerse the coated polyurethane foam obtained in step S6 into 500 mL of 0.15 mol / L copper sulfate solution, let it stand under 365 nm ultraviolet light for 40 min, take it out, ultrasonically wash it with deionized water for 10 min, and place it in a vacuum drying oven at 60 °C for 5 h to obtain a back pad material containing biocrystals.

[0036] Example 3

[0037] This embodiment provides a method for preparing a back pad material containing biocrystals, including the following steps: S1. A quaternary ammonium salt chain extender was prepared according to the method of Example 1; S2. Mix 7g of quaternary ammonium salt chain extender and 15g of silane coupling agent KH560, heat to 115℃, and stir for 1.5h to obtain hyperbranched chain extender; S3. Mix 20g tourmaline powder, 30g jade powder, and 10g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S4. Add 10g of hyperbranched chain extender to 95wt% ethanol aqueous solution, adjust the pH value to 3.5-4.5 with acetic acid, hydrolyze for 6h, add 30g of biocrystal powder, heat to 80℃, sonicate at 200W for 3h, filter, wash, dry, grind, and pass through a 3000-mesh sieve to obtain the modified chain extender. S5. Mix 75g of polyether polyol 330 (molecular weight 4800, industrial grade) and 25g of polyester polyol 204 (molecular weight 3000, industrial grade), add 15g of modified chain extender, 0.2g of triethylenediamine, 0.15g of dibutyltin dilaurate, 1.2g of silicone foaming agent and 3g of water, stir at 1000r / min for 2min to obtain white material. Take 105g of white material and add 50g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S6. Add 1.2g dopamine and 2.7g sodium periodate to 500mL of sodium acetate buffer solution with a pH of 5-6. Immerse the foamed polyurethane obtained in step S5 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain the coated foamed polyurethane. S7. Immerse the coated polyurethane foam obtained in step S6 into 500 mL of 0.1 mol / L copper nitrate solution, let it stand under 365 nm ultraviolet light for 30 min, take it out, ultrasonically wash it with deionized water for 10 min, and place it in a vacuum drying oven at 60 °C for 5 h to obtain a back pad material containing biocrystals.

[0038] Comparative Example 1 Compared to Example 3, the only difference is that steps S1 and S2 were omitted; instead, the silane coupling agent KH560 was directly used to modify the biocrystal powder. In this case, the silane coupling agent KH560 replaced the hyperbranched chain extender by an equal mass, and the quaternary ammonium salt chain extender was not added to the white material system. This verifies the effect of the quaternary ammonium salt cationic group material on the material.

[0039] Includes the following steps: S1. Mix 20g tourmaline powder, 30g jade powder, and 10g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S2. Add 10g of silane coupling agent KH560 to a 95wt% ethanol aqueous solution, adjust the pH to 3.5-4.5 with acetic acid, hydrolyze for 6h, add 30g of biocrystal powder, heat to 80℃, sonicate at 200W for 3h, filter, wash, dry, grind, and pass through a 3000-mesh sieve to obtain modified biocrystal powder. S3. Mix 75g of polyether polyol 330 (molecular weight 4800, industrial grade) and 25g of polyester polyol 204 (molecular weight 3000, industrial grade), add 15g of modified biocrystal powder, 0.2g of triethylenediamine, 0.15g of dibutyltin dilaurate, 1.2g of silicone foaming agent and 3g of water, stir at 1000r / min for 2min to obtain white material. Take 105g of white material and add 50g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S4. Add 1.2g dopamine and 2.7g sodium periodate to 500mL of sodium acetate buffer solution with a pH of 5-6. Immerse the foamed polyurethane obtained in step S3 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain the coated foamed polyurethane. S5. Immerse the coated polyurethane foam obtained in step S4 into 500 mL of 0.1 mol / L copper nitrate solution, let it stand under 365 nm ultraviolet light for 30 min, take it out, ultrasonically wash it with deionized water for 10 min, and place it in a vacuum drying oven at 60 °C for 5 h to obtain a back pad material containing biocrystals.

[0040] Comparative Example 2 Compared with Example 3, the only difference is that step S2 was not performed, and the quaternary ammonium salt chain extender and silane coupling agent KH560 were used independently: the quaternary ammonium salt chain extender was directly added to the white material system; the biocrystal powder was surface modified separately using silane coupling agent KH560, thereby verifying that the quaternary ammonium salt chain extender must form a hyperbranched structure with KH560 in advance and be grafted onto the surface of the biocrystal powder in order to exert a synergistic effect.

[0041] According to Example 3, in step S2, the mass ratio of quaternary ammonium salt chain extender to silane coupling agent KH560 is 7:15. Therefore, in step S3, the amount of silane coupling agent KH560 added is 10g / 22×15=6.8g.

[0042] According to Example 3, in step S4, the mass ratio of hyperbranched chain extender to biocrystal powder is 1:3. Therefore, in 15g of modified chain extender, the amount of quaternary ammonium salt chain extender added is equivalent to the mass of hyperbranched chain extender, which is 3.75g, and the amount of biocrystal powder is 11.25g.

[0043] The subsequent addition logic is the same as this comparison.

[0044] Includes the following steps: S1. A quaternary ammonium salt chain extender was prepared according to the method of Example 1; S2. Mix 20g tourmaline powder, 30g jade powder, and 10g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S3. Add 6.8g of silane coupling agent KH560 to a 95wt% ethanol aqueous solution, adjust the pH to 3.5-4.5 with acetic acid, hydrolyze for 6h, add 30g of biocrystal powder, heat to 80℃, sonicate at 200W for 3h, filter, wash, dry, grind, and pass through a 3000-mesh sieve to obtain modified biocrystal powder. S4. Mix 75g of polyether polyol 330 (molecular weight 4800, industrial grade) and 25g of polyester polyol 204 (molecular weight 3000, industrial grade), add 3.75g of quaternary ammonium salt chain extender, 11.25g of modified biocrystal powder, 0.2g of triethylenediamine, 0.15g of dibutyltin dilaurate, 1.2g of silicone foaming agent and 3g of water, stir at 1000r / min for 2min to obtain white material. Take 105g of white material and add 50g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S5. Add 1.2g dopamine and 2.7g sodium periodate to 500mL of sodium acetate buffer solution with a pH of 5-6. Immerse the foamed polyurethane obtained in step S4 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain the coated foamed polyurethane. S6. Immerse the coated polyurethane foam obtained in step S5 into 500 mL of 0.1 mol / L copper nitrate solution, let it stand under 365 nm ultraviolet light for 30 min, take it out, ultrasonically wash it with deionized water for 10 min, and dry it in a vacuum drying oven at 60 °C for 5 h to obtain a back pad material containing biocrystals.

[0045] Comparative Example 3 Compared with Example 3, the only difference is that steps S2 and S4 were not performed. Instead, the quaternary ammonium salt chain extender and biocrystal powder were directly added to the white material system to verify that the biocrystal powder must undergo surface modification in order to be uniformly dispersed in polyurethane.

[0046] Includes the following steps: S1. A quaternary ammonium salt chain extender was prepared according to the method of Example 1; S2. Mix 20g tourmaline powder, 30g jade powder, and 10g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S3. Mix 75g of polyether polyol 330 (molecular weight 4800, industrial grade) and 25g of polyester polyol 204 (molecular weight 3000, industrial grade), add 3.75g of quaternary ammonium salt chain extender, 11.25g of biocrystal powder, 0.2g of triethylenediamine, 0.15g of dibutyltin dilaurate, 1.2g of silicone foaming agent and 3g of water, stir at 1000r / min for 2min to obtain white material. Take 105g of white material and add 50g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S4. Add 1.2g dopamine and 2.7g sodium periodate to 500mL of sodium acetate buffer solution with a pH of 5-6. Immerse the foamed polyurethane obtained in step S3 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain the coated foamed polyurethane. S5. Immerse the coated polyurethane foam obtained in step S4 into 500 mL of 0.1 mol / L copper nitrate solution, let it stand under 365 nm ultraviolet light for 30 min, take it out, ultrasonically wash it with deionized water for 10 min, and place it in a vacuum drying oven at 60 °C for 5 h to obtain a back pad material containing biocrystals.

[0047] Comparative Example 4 Compared to Example 3, the only difference is that the quaternary ammonium salt group was removed and replaced with a small molecule polyol (3-amino-1,2-propanediol) that does not contain quaternary ammonium salt, while the biocrystal powder remained unmodified. This verifies that the quaternary ammonium salt cationic group and KH560 synergistically affect the material after modification of the biocrystal powder.

[0048] Includes the following steps: S1. Mix 20g tourmaline powder, 30g jade powder, and 10g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S2. Mix 75g of polyether polyol 330 (molecular weight 4800, industrial grade) and 25g of polyester polyol 204 (molecular weight 3000, industrial grade), add 3.75g of 3-amino-1,2-propanediol, 11.25g of biocrystal powder, 0.2g of triethylenediamine, 0.15g of dibutyltin dilaurate, 1.2g of silicone foaming agent and 3g of water, stir at 1000r / min for 2min to obtain white material. Take 105g of white material and add 50g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S3. Add 1.2g dopamine and 2.7g sodium periodate to 500mL of sodium acetate buffer solution with pH 5-6. Immerse the foamed polyurethane obtained in step S2 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain the coated foamed polyurethane. S4. Immerse the coated polyurethane foam obtained in step S3 into 500 mL of 0.1 mol / L copper nitrate solution, let it stand under 365 nm ultraviolet light for 30 min, take it out, ultrasonically wash it with deionized water for 10 min, and place it in a vacuum drying oven at 60 °C for 5 h to obtain a back pad material containing biocrystals.

[0049] Comparative Example 5 Compared to Example 3, the only difference is that steps S1 to S4 were not performed. This was to verify the effect of the modified chain extender on the material.

[0050] Includes the following steps: S1. Mix 75g of polyether polyol 330 (molecular weight 4800, industrial grade) and 25g of polyester polyol 204 (molecular weight 3000, industrial grade), add 15g of 3-amino-1,2-propanediol, 0.2g of triethylenediamine, 0.15g of dibutyltin dilaurate, 1.2g of silicone foaming agent and 3g of water, stir at 1000r / min for 2min to obtain white material. Take 105g of white material and add 50g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S2. Add 1.2g dopamine and 2.7g sodium periodate to 500mL of sodium acetate buffer solution with a pH of 5-6. Immerse the foamed polyurethane obtained in step S1 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain the coated foamed polyurethane. S3. Immerse the coated polyurethane foam obtained in step S2 into 500 mL of 0.1 mol / L copper nitrate solution, let it stand under 365 nm ultraviolet light for 30 min, take it out, ultrasonically wash it with deionized water for 10 min, and place it in a vacuum drying oven at 60 °C for 5 h to obtain the back pad material.

[0051] Comparative Example 6 The only difference from Example 3 is that step S6 was omitted. This was to verify the effect of the polydopamine layer on the material.

[0052] Includes the following steps: S1. A quaternary ammonium salt chain extender was prepared according to the method of Example 1; S2. Mix 7g of quaternary ammonium salt chain extender and 15g of silane coupling agent KH560, heat to 115℃, and stir for 1.5h to obtain hyperbranched chain extender; S3. Mix 20g tourmaline powder, 30g jade powder, and 10g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S4. Add 10g of hyperbranched chain extender to 95wt% ethanol aqueous solution, adjust the pH value to 3.5-4.5 with acetic acid, hydrolyze for 6h, add 30g of biocrystal powder, heat to 80℃, sonicate at 200W for 3h, filter, wash, dry, grind, and pass through a 3000-mesh sieve to obtain the modified chain extender. S5. Mix 75g of polyether polyol 330 (molecular weight 4800, industrial grade) and 25g of polyester polyol 204 (molecular weight 3000, industrial grade), add 15g of modified chain extender, 0.2g of triethylenediamine, 0.15g of dibutyltin dilaurate, 1.2g of silicone foaming agent and 3g of water, stir at 1000r / min for 2min to obtain white material. Take 105g of white material and add 50g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S6. Immerse the foamed polyurethane obtained in step S5 into 500 mL of 0.1 mol / L copper nitrate solution, let it stand under 365 nm ultraviolet light for 30 min, take it out, ultrasonically wash it with deionized water for 10 min, and place it in a vacuum drying oven at 60 °C for 5 h to obtain a back pad material containing biocrystals.

[0053] Comparative Example 7 Compared with Example 3, the only difference is that step S7 was not performed to verify the effect of copper ion impregnation and light irradiation treatment on the material.

[0054] Includes the following steps: S1. A quaternary ammonium salt chain extender was prepared according to the method of Example 1; S2. Mix 7g of quaternary ammonium salt chain extender and 15g of silane coupling agent KH560, heat to 115℃, and stir for 1.5h to obtain hyperbranched chain extender; S3. Mix 20g tourmaline powder, 30g jade powder, and 10g opal powder, grind them, and pass them through a 3000-mesh sieve to obtain bio-crystal powder; S4. Add 10g of hyperbranched chain extender to 95wt% ethanol aqueous solution, adjust the pH value to 3.5-4.5 with acetic acid, hydrolyze for 6h, add 30g of biocrystal powder, heat to 80℃, sonicate at 200W for 3h, filter, wash, dry, grind, and pass through a 3000-mesh sieve to obtain the modified chain extender. S5. Mix 75g of polyether polyol 330 (molecular weight 4800, industrial grade) and 25g of polyester polyol 204 (molecular weight 3000, industrial grade), add 15g of modified chain extender, 0.2g of triethylenediamine, 0.15g of dibutyltin dilaurate, 1.2g of silicone foaming agent and 3g of water, stir at 1000r / min for 2min to obtain white material. Take 105g of white material and add 50g of black material diphenylmethane diisocyanate, stir at 1000r / min for 10s, pour into a mold, place in an oven at 50℃, let stand to foam and cure, demold after 30min, and cure at room temperature for 72h to obtain foamed polyurethane; S6. Add 1.2g dopamine and 2.7g sodium periodate to 500mL of sodium acetate buffer solution with a pH of 5-6. Immerse the foamed polyurethane obtained in step S5 into the solution, let it stand for 30min, take it out, and ultrasonically wash it with deionized water for 10min to obtain coated foamed polyurethane, which is the back pad material containing biocrystals.

[0055] Test Example 1 The performance of the biocrystal-containing back pad materials prepared in Examples 1-3 and Comparative Examples 1-7 was tested, and the results are shown in Table 1.

[0056] 1. Rebound rate test: Cut the sample into specimens with dimensions of 100mm×100mm×50mm. Drop a standard steel ball with a diameter of 16mm and a mass of 16.3g from a height of 500mm to impact the surface of the specimen. Use a photoelectric sensor to record the rebound height of the steel ball. Rebound rate (%) = (rebound height / drop height) × 100%. Test each specimen 5 times and take the average value.

[0057] 2. Compression set test: Cut the sample into specimens with dimensions of 50mm×50mm×25mm, compress them to 50% of their original thickness in a compression device, keep them in a constant temperature chamber of 70℃±1℃ for 22h, remove them and let them recover at room temperature for 30min, and measure the thickness of the specimen after recovery. Compression set (%) = (original thickness - recovered thickness) / (original thickness - compressed thickness) × 100%, and take the average value of 3 specimens in each group of tests.

[0058] 3. Springback retention test after compression cycle: The sample was cut into specimens with dimensions of 150mm×150mm×50mm and placed on a fatigue testing machine. The specimens were repeatedly compressed to 75% of their original thickness at a frequency of 1Hz for a total of 50,000 cycles. The springback rate of the specimens was measured before and after the cycles. Springback retention rate (%) = (springback rate after cycle / springback rate before cycle) × 100%.

[0059] 4. Far-infrared emission performance test: The samples were tested using the method of GB / T30127-2013.

[0060] 5. Tensile strength and elongation at break test: The test was conducted in accordance with GB / T 6344-2008 "Determination of tensile strength and elongation at break of flexible foam polymer materials". The foam material was cut into dumbbell-shaped specimens (total length not less than 150 mm, width of the narrow part (25±1) mm, thickness (10±1) mm). The tensile test was carried out on a universal testing machine at a tensile rate of (500±50) mm / min. The maximum load at break and the change in the spacing between the marks were recorded. The tensile strength and elongation at break were calculated respectively. The median of 5 specimens in each group was taken.

[0061] 6. Sterilization Rate Test: The antibacterial activity of the samples was evaluated using *Escherichia coli* (ATCC25922). 2 mL of the stock bacterial solution was mixed with 100 mL of LB growth medium and incubated for 24 h at 37°C and 200 rpm. The incubated bacteria were then subjected to a (1-10) × 10⁻⁶ ppm reaction. 7 The sample was suspended at a density of cfu / mL. 0.1 g of sample was placed in each well of a 24-well plate, and 500 μL of bacterial suspension was added. After incubation at 37°C for 6 h, the bacterial suspension from each well was diluted, and 50 μL was inoculated onto an LB bacterial culture plate. The plate was incubated at 37°C for 24 h, and the colony count was recorded as n1. The colony count of the control group was recorded as n0. For another group, during bacterial culture, the bacterial suspension and sample were irradiated together with near-infrared light (808 nm, 1 W / cm²). 2 10 min.

[0062] Calculate the sterilization rate:

[0063] Table 1

[0064] Note: In antibacterial rate, "conventional" refers to the antibacterial rate without near-infrared light irradiation, while "illuminated" refers to the antibacterial rate after near-infrared light irradiation.

[0065] As can be seen from the table above, the biocrystal-containing back pad materials prepared in Examples 1-3 of the present invention have good comprehensive performance.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 back pad material containing biocrystals, characterized in that, Includes the following steps: S1. Provide a quaternary ammonium salt chain extender, prepare a hyperbranched chain extender with a silane coupling agent, and then react it with biocrystal powder to obtain a modified chain extender; S2. Mix polyether polyol and polyester polyol, add chain extender, triethylenediamine, catalyst, foam stabilizer and water, stir and mix evenly to obtain white material; add black material to white material, stir and mix evenly, pour into mold, heat and let stand to foam and cure, demold to obtain foamed polyurethane. S3. Add dopamine and sodium periodate to sodium acetate buffer solution, immerse polyurethane foam in the solution, let stand, take out, wash, and obtain coated polyurethane foam. S4. Immerse the coated polyurethane foam in a copper salt solution, let it stand under ultraviolet light, remove it, wash it, and dry it to obtain a back pad material containing biocrystals.

2. The preparation method according to claim 1, characterized in that, The preparation method of the quaternary ammonium salt chain extender is as follows: methyl bromoacetate and N,N-dimethylalkylamine are reacted to obtain N,N-dimethylalkylN-acetate quaternary ammonium salt, which is then reacted with 3-amino-1,2-propanediol to obtain the quaternary ammonium salt chain extender.

3. The preparation method according to claim 2, characterized in that, The molar ratio of methyl bromoacetate to N,N-dimethylalkylamine is 1.2-1.7:1, the reaction temperature is 40-70℃, and the time is 20-28h; the molar ratio of N,N-dimethylalkylN-acetate quaternary ammonium salt to 3-amino-1,2-propanediol is 1:1.5-2, the melting reaction temperature is 75-85℃, and the time is 10-15h.

4. The preparation method according to claim 2, characterized in that, The N,N-dimethylalkylamine is selected from at least one of N,N-dimethyltetradecylamine, N,N-dimethyldodecylamine, N,N-dimethylpentadecanamine, and N,N-dimethyltridecylamine.

5. The preparation method according to claim 2, characterized in that, The specific reaction in step S1 is as follows: S101. A hyperbranched chain extender is prepared by mixing a quaternary ammonium salt chain extender and a silane coupling agent KH560 and heating them together. S102. Mix tourmaline powder, jade powder, and opal powder, grind them, and sieve them to obtain bio-crystal powder; S103. Add the hyperbranched chain extender to an ethanol-water solution, adjust the pH value, perform a hydrolysis reaction, add biocrystal powder, heat and sonicate, filter, wash, dry, grind, and sieve to obtain the modified chain extender.

6. The preparation method according to claim 5, characterized in that, In step S101, the mass ratio of the quaternary ammonium salt chain extender to the silane coupling agent KH560 is 0.5-1:1-2, and the heating temperature is 110-120℃ for 1-2 hours; in step S102, the mass ratio of tourmaline powder, jade powder, and opal powder is 3-5:5-10:1-4; in step S103, the concentration of the ethanol aqueous solution is 90-95 wt%, the pH value is adjusted to 3.5-4.5, the hydrolysis reaction time is 4-8 hours, the mass ratio of the hyperbranched chain extender to the biocrystal powder is 1:2-4, and the heating and ultrasonic reaction temperature is 75-85℃ for 2-4 hours.

7. The preparation method according to claim 2, characterized in that, In step S2, the mass ratio of polyether polyol, polyester polyol, modified chain extender, triethylenediamine, catalyst, foam stabilizer, and water is 7-8:2-3:1-2:0.01-0.03:0.01-0.02:0.1-0.15:0.2-0.

4. The mass ratio of white material to black material is 10-11:4.5-5.

5. The black material is diphenylmethane diisocyanate. The catalyst is an organotin catalyst. The foam stabilizer is an organosilicon foam stabilizer. The heating and settling temperature is 45-55℃, and the time is 20-40 minutes.

8. The preparation method according to claim 2, characterized in that, In step S3, the mass ratio of dopamine to sodium periodate is 1-1.5:2-3, and the pH value of the sodium acetate buffer solution is 5-6.

9. The preparation method according to claim 2, characterized in that, The concentration of the copper salt solution in step S4 is 0.05-0.15 mol / L, the copper salt is selected from at least one of copper chloride, copper sulfate, and copper nitrate, the wavelength of the ultraviolet light is 365 nm, and the standing time is 20-40 min.

10. A back pad material containing biocrystals prepared by the preparation method according to any one of claims 1-9.

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