Polyether type super-wear-resistant halogen-free flame-retardant TPU composite material and preparation method therefor

Abstract

The present invention belongs to the technical field of the processing of polyether type TPU plastics. Disclosed are a polyether type super-wear-resistant halogen-free flame-retardant TPU composite material and a preparation method therefor. The composite material comprises the following raw materials in parts by mass: 90-110 parts of a polyether type thermoplastic polyurethane elastomer, 10-15 parts of a composite flame-retardant filler, 10-12 parts of a composite wear-resistant aggregate, 1-2 parts of a compatibilizer, 0.1-0.5 parts of an ultraviolet absorber, and 0.2-0.6 parts of an antioxidant. A rough surface is formed on the surfaces of hydroxylated calcium sulfate whiskers, thereby increasing the contact area between the composite flame-retardant filler and the polyether type TPU composite material; and the composite flame-retardant filler is mechanically interlocked with the polyether type TPU composite material, thereby improving the binding force between the composite flame-retardant filler and the polyether type TPU composite material. A modified phytic acid-vanillic aldehyde compound is adsorbed into the pores of a Co-Mn-O nanomaterial in the modified calcium sulfate whiskers and forms an organic-inorganic flame-retardant material together with the modified calcium sulfate whiskers, thereby improving the flame retardance.

Description

A polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material and its preparation method Technical Field

[0001] This invention relates to the field of polyether-type TPU plastic processing technology, specifically to a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material and its preparation method. Background Technology

[0002] Thermoplastic polyurethane elastomers (TPUs) come in two types: polyester and polyether. Polyether-type TPUs are linear block copolymers composed of soft-segment polyether polyols, diisocyanates, and hard segments of chain extenders. Polyether-type TPUs can be plasticized upon heating, exhibiting excellent processing performance. They also possess superior comprehensive properties such as high strength, high toughness, wear resistance, and oil resistance. Due to their good processing performance, they are widely used in industries such as automotive, coatings, defense, building materials, clothing, and wire and cable. However, the limiting oxygen index (LOI) of TPUs is only about 19%, which limits their application in areas with high fire safety requirements, such as cables.

[0003] Thermoplastic polyurethane elastomers have poor flame retardant properties, exhibiting dripping during combustion and producing thick black smoke. Furthermore, polyurethane materials generate harmful gases at high temperatures, causing environmental pollution. Adding inorganic and organic flame retardant materials to polyether-type thermoplastic polyurethane elastomers can effectively improve the flame retardant properties of the composite material. However, inorganic flame retardant materials tend to migrate and precipitate within the polyether-type thermoplastic polyurethane elastomer, and the synergistic flame retardant effect of organic and inorganic flame retardant composites is poor. Phytic acid and vanillin, as bio-based flame retardants, have good flame retardant effects, but the water solubility of phytic acid makes the flame retardant material prone to moisture absorption, affecting the service life of polyether-type thermoplastic polyurethane elastomer composites. Summary of the Invention

[0004] The present invention aims to provide a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material and its preparation method: Porous Co-Mn-O nanomaterials are synthesized in situ on the surface of hydroxylated calcium sulfate whiskers. The hydroxylated calcium sulfate whiskers, acting as a carrier for the Co-Mn-O nanomaterials, possess an excellent aspect ratio, enabling them to support a larger amount of Co-Mn-O nanomaterials and improve flame-retardant performance. An organosilicon composite is grafted onto a phytic acid-vanillin composite to improve its hydrophobic properties and avoid the high water solubility and easy water absorption of phytic acid in the composite. The modified phytic acid-vanillin composite is then adsorbed into the pores of the Co-Mn-O nanomaterials within the modified calcium sulfate whiskers. It forms an organic-inorganic flame retardant material with modified calcium sulfate whiskers, improving flame retardant performance; the monomer formed by the reaction of dicyandiamide and adiponitrile is grafted onto the surface of pretreated wear-resistant aggregate through isocyanate silane grafting. The amino groups contained in the monomer can bind with the polyether-type TPU molecular chains through hydrogen bonds, so that the wear-resistant aggregate is uniformly dispersed in the polyether-type TPU composite material, avoiding the migration and precipitation of the wear-resistant aggregate; calcium phosphate oligomers can bind with the polyether-type TPU composite material molecular chains through hydrogen bonds to form a cross-linked network structure, increasing the cross-linking density of the polyether-type TPU composite material, making the polyether-type TPU composite material more compact, increasing the dissipation effect of external forces, exhibiting excellent resistance to dynamic friction, and improving wear resistance.

[0005] The technical problem to be solved by this invention is that inorganic flame retardant materials are prone to migration and precipitation in polyether-type thermoplastic polyurethane elastomers, and the synergistic flame retardant effect of organic and inorganic flame retardant composite materials is poor. Phytic acid and vanillin, as bio-based flame retardants, have good flame retardant effects, but the water solubility of phytic acid makes the flame retardant materials prone to moisture absorption, which affects the service life of polyether-type thermoplastic polyurethane elastomer composite materials.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material, comprising the following raw materials in parts by weight: 90-110 parts of polyether-type thermoplastic polyurethane elastomer, 10-15 parts of composite flame-retardant filler, 10-12 parts of composite wear-resistant aggregate, 1-2 parts of compatibilizer, 0.1-0.5 parts of ultraviolet absorber, and 0.2-0.6 parts of antioxidant.

[0007] A method for preparing a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material includes the following steps: S1. Place polyether-type thermoplastic polyurethane elastomer, composite flame-retardant filler, composite wear-resistant aggregate, compatibilizer, antibacterial agent, ultraviolet absorber, and antioxidant in a mixer, and mix at high speed for 3-5 minutes at 40-60℃ to obtain a mixture.

[0008] S2. The mixture is placed in a twin-screw extruder and extruded and granulated to obtain a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material.

[0009] Furthermore, the compatibilizer is a hydroxyl-terminated polyether-modified silicone oil, preferably XIAMETER OFX-3667.

[0010] Furthermore, the antioxidant is selected from any one of antioxidant 300, antioxidant 168, antioxidant 1010, and antioxidant 626.

[0011] Furthermore, the ultraviolet absorber is selected from any one of ultraviolet absorbers UV-P, UV-O, UV-9, and UV-531.

[0012] Furthermore, the twin-screw extruder process is as follows: the temperature of the twin-screw feeding zone is 180-190℃, the temperature of the plasticizing zone is 190-200℃, the die head temperature is 200-210℃, and the screw speed is 70-90 rpm.

[0013] Furthermore, the composite flame retardant filler is prepared by reacting phytic acid, vanillin, and organosilicon complex, and then mixing it with modified calcium sulfate whiskers. Specifically, it is prepared by the following steps: A1. Vanillin is added to ethanol and stirred evenly. Phytic acid, 4-dimethylpyridine at a concentration of 4 g / L and N,N-dicyclohexylcarbodiimide are added. The mixture is stirred and reacted at 130°C for 3 h. After filtration, it is washed three times with deionized water and dried in an oven at 80°C for 10 min to obtain the phytic acid-vanillin complex.

[0014] In this process, 4-dimethylpyridine acts as a catalyst, enabling the phosphorus hydroxyl groups in phytic acid to react with the hydroxyl groups in vanillin. N,N-dicyclohexylcarbodiimide acts as a water absorbent, absorbing the water molecules produced by the reaction of phytic acid and vanillin to form a phytic acid-vanillin complex. This complex can be catalyzed to form carbon, which, together with modified calcium sulfate whiskers, forms an organic-inorganic flame retardant material, thus improving the flame retardant performance.

[0015] Furthermore, the ratio of vanillin, ethanol, phytic acid, 4-dimethylpyridine, and N,N-dicyclohexylcarbodiimide is (7.2-7.4)g:(35-45)mL:(13-17)g:(0.1-0.3)g:(1.5-1.7)g.

[0016] A2. Add the phytic acid-vanillin complex to deionized water and ethanol, stir well, add organosilicon complex and 36% sodium hydroxide solution to adjust the pH to 4.5, heat to 80℃, stir and react for 1 hour, cool to room temperature, remove ethanol by concentration and evaporation, filter, wash 3 times with deionized water, and dry in an 80℃ oven for 10 minutes to obtain the phytic acid-vanillin complex.

[0017] In particular, under alkaline conditions at 80℃, the aldehyde group of vanillin in the phytic acid-vanillin complex can undergo a Schiff base reaction with the amino group in the organosilicon complex. The organosilicon complex is grafted onto the phytic acid-vanillin complex to form a modified phytic acid-vanillin complex, which improves the hydrophobic properties of the phytic acid-vanillin complex and avoids the high water solubility of phytic acid in the phytic acid-vanillin complex, which makes it easy to absorb water and affect the stability and service life of polyether TPU composite materials in humid environments.

[0018] Furthermore, the ratio of phytic acid-vanillin complex, deionized water, ethanol, and organosilicon complex is (4-6)g:(70-90)mL:(15-25)mL:(6-7)g.

[0019] A3. Add the modified phytic acid-vanillin composite to ethanol, stir, add modified calcium sulfate whiskers, apply negative pressure at -0.1MPa for 10 min, heat to 85℃, stir until ethanol evaporates, wash 3 times with deionized water, and dry in an oven at 80℃ for 10 min to obtain the composite flame retardant filler.

[0020] Among them, the porous structure of Co-Mn-O nanomaterials in modified calcium sulfate whiskers has good adsorption performance, which can adsorb the modified phytic acid-vanillin complex into the pores of Co-Mn-O nanomaterials in modified calcium sulfate whiskers, so that the organic flame retardant modified phytic acid-vanillin complex and the inorganic flame retardant modified calcium sulfate whiskers are precisely combined, thereby improving the flame retardant performance.

[0021] It should also be noted that during combustion, the modified phytic acid-vanillin complex decomposes upon heating and detaches from the pores of the Co-Mn-O nanomaterials, without affecting the smoke-suppressing performance of the Co-Mn-O nanomaterials.

[0022] Furthermore, the ratio of modified phytic acid-vanillin complex, ethanol, and modified calcium sulfate whiskers is (2-3)g:(25-35)mL:(0.2-0.4)g.

[0023] Furthermore, the organosilicon complex is prepared by the following steps: N-aminoethyl-3-aminopropylmethyldimethoxysilane and octamethylcyclotetrasiloxane are mixed and stirred evenly. Sodium hydroxide, deionized water and sodium dodecylbenzenesulfonate are added. After stirring and reacting at 80°C for 5 hours, the temperature is lowered to 40°C. Hydrochloric acid with a mass fraction of 36% is added to adjust the pH to neutral. The filtrate is collected by filtration to obtain the organosilicon complex.

[0024] Sodium hydroxide is used as a catalyst and sodium dodecylbenzenesulfonate is used as an emulsifier to react N-aminoethyl-3-aminopropylmethyldimethoxysilane with octamethylcyclotetrasiloxane, grafting N-aminoethyl-3-aminopropylmethyldimethoxysilane onto octamethylcyclotetrasiloxane to obtain amino-modified organosilicon.

[0025] Furthermore, the ratio of N-aminoethyl-3-aminopropylmethyldimethoxysilane, octamethylcyclotetrasiloxane, sodium hydroxide, deionized water, and sodium dodecylbenzenesulfonate is (4-5)g:(5-6)g:(0.01-0.03)g:(8-12)mL:(0.4-0.6)g.

[0026] Furthermore, the modified calcium sulfate whiskers are prepared by mixing hydroxylated calcium sulfate whiskers with a cobalt source and a manganese source, followed by calcination.

[0027] Furthermore, the hydroxylated calcium sulfate whiskers have a length of 12-26 μm and a diameter of 0.5-1.5 μm.

[0028] Furthermore, the manganese source is selected from manganese sulfate hydrate or manganese nitrate.

[0029] Furthermore, the cobalt source is selected from cobalt sulfate heptahydrate or cobalt nitrate.

[0030] Furthermore, the roasting temperature is 450-550℃, and the roasting time is 3-5 hours.

[0031] Furthermore, the modified calcium sulfate whiskers are prepared by the following steps: Cobalt source and manganese source are added to ethanol and deionized water, stirred evenly, hydroxylated calcium sulfate whiskers are added, stirred for 10 min, sodium carbonate aqueous solution with a concentration of 0.4-0.6 mol / L is added until the pH is 8.5, kept overnight, filtered, washed 3 times with deionized water, dried in an oven at 80℃ for 5 h, placed in a muffle furnace, calcined at 500℃ for 4 h, and cooled to room temperature to obtain modified calcium sulfate whiskers.

[0032] The hydroxyl groups on the surface of the hydroxylated calcium sulfate whiskers can combine with cobalt and manganese ions from the cobalt and manganese sources, causing the cobalt and manganese sources to be deposited on the surface of the hydroxylated calcium sulfate whiskers. Sodium bicarbonate, as a precipitant, can combine with the cobalt and manganese ions deposited on the surface of the hydroxylated calcium sulfate whiskers to form carbonate precipitates.

[0033] Furthermore, high-temperature calcination is carried out at 500℃, and the carbonate precipitate decomposes under heat to form cobalt oxide metal. During the calcination process, manganese partially replaces cobalt in the cobalt oxide lattice, allowing manganese to be incorporated into the cobalt oxide metal lattice to form Co-Mn-O nanomaterials. In addition, the carbonate precipitate releases gas during the thermal decomposition process, forming porous Co-Mn-O nanomaterials. This achieves in-situ synthesis of porous Co-Mn-O nanomaterials on the surface of hydroxylated calcium sulfate whiskers.

[0034] Furthermore, the ratio of cobalt source, manganese source, ethanol, deionized water, and hydroxylated calcium sulfate whiskers is (1.3-1.34)g:(0.5-0.7)g:(16-20)mL:(170-190)mL:(2-3)g.

[0035] Furthermore, the porous Co-Mn-O nanomaterials have pore sizes of 30-50 nm.

[0036] Furthermore, hydroxylated calcium sulfate whiskers are specifically prepared by the following steps: Calcium sulfate whiskers are added to a 0.02-0.03 mol / L trisodium phosphate solution, ultrasonically treated, stirred evenly, filtered, washed, and dried to obtain hydroxylated calcium sulfate whiskers.

[0037] Among them, the surface treatment of calcium sulfate whiskers with trisodium phosphate results in the calcium sulfate whiskers carrying a large number of hydroxyl groups on the surface, which increases the surface polarity of the calcium sulfate whiskers, and the calcium sulfate whiskers are not affected by the external environment and do not undergo crystal transformation.

[0038] Furthermore, the ratio of calcium sulfate whiskers to trisodium phosphate solution is (2-3) g: (80-120) mL.

[0039] Furthermore, the composite wear-resistant aggregate is prepared by mixing modified wear-resistant aggregate and calcium phosphate oligomer, specifically by the following steps: Phosphoric acid is added to ethanol and stirred to obtain a phosphate ethanol solution. Calcium chloride dihydrate is added to ethanol and stirred at 25°C for 30 min. Triethylamine is added and stirred for 10 min. The phosphate ethanol solution is added and stirred for 12 h. The precipitate is collected by centrifugation at 8000 rpm. The precipitate is washed three times with ethanol to remove triethylamine and added to ethanol to form a stable emulsion, obtaining calcium phosphate oligomer. The calcium phosphate oligomer and modified wear-resistant aggregate are mixed and stirred evenly to obtain the composite wear-resistant aggregate.

[0040] In the ethanol solution of phosphoric acid, phosphate ions can combine with calcium ions in calcium chloride dihydrate to form calcium phosphate oligomers. These calcium phosphate oligomers have an amorphous and gel-like structure and can combine with polyether-type TPU molecular chains through hydrogen bonds to form a cross-linked network structure. This increases the cross-linking density of the polyether-type TPU composite material, making it more compact and increasing the dissipation effect of external forces, resulting in excellent resistance to dynamic friction.

[0041] Furthermore, the cross-linked network structure formed by calcium phosphate oligomers and polyether-type TPU can encapsulate the modified wear-resistant aggregate in the polyether-type TPU composite material, thereby improving the bonding force of the composite wear-resistant aggregate in the polyether-type TPU composite material and enhancing the high wear resistance of the polyether-type TPU composite material.

[0042] Furthermore, the ratio of phosphoric acid to ethanol is (2-3) g: (25-35) mL.

[0043] Furthermore, the ratio of calcium chloride dihydrate, ethanol, triethylamine, and phosphate ethanol solution is (0.4-0.5)g:(50-70)mL:(6-6.2)g:(25-35)mL.

[0044] Furthermore, the mass ratio of calcium phosphate oligomer to modified wear-resistant aggregate is (25-35):(2-3).

[0045] Furthermore, the modified wear-resistant aggregate is prepared by reacting dicyandiamide and adiponitrile to form a monomer, which is then mixed and reacted with wear-resistant aggregate surface-treated with isocyanate silane.

[0046] Furthermore, the isocyanate silane is selected from 3-isocyanopropyltrimethoxysilane or isocyanopropyltriethoxysilane.

[0047] Furthermore, the wear-resistant aggregate is selected from any one of nano alumina, nano calcium silicate, nano zirconium oxide, nano calcium carbonate, nano silicon carbide, and nano silicon dioxide.

[0048] Furthermore, the wear-resistant aggregate has a particle size of 100-300nm.

[0049] Furthermore, the modified wear-resistant aggregate is prepared by the following steps: B1. Dicyandiamide and potassium hydroxide are added to 2-methoxyethanol and stirred at 200 rpm for 10 min. Adiponitrile is added, the temperature is raised to 125℃, and the mixture is stirred for 6 h. The mixture is filtered and washed with methanol to obtain the reaction product. The reaction product is dried in a vacuum oven at 80℃ and 10 Pa for 24 h to obtain the monomer.

[0050] In this synthesis, 2-methoxyethanol was used as the solvent and potassium hydroxide as the catalyst. The reaction was carried out at 125°C with stirring, allowing dicyandiamide to react with adiponitrile to obtain the monomer. The synthesis steps are shown below:

[0051] Furthermore, the ratio of dicyandiamide, potassium hydroxide, 2-methoxyethanol, and adiponitrile is (4-6)g:(1-2)g:(45-55)mL:(2.5-2.9)mL.

[0052] B2. Add wear-resistant aggregate and isocyanate silane to ethanol and deionized water, stir evenly, adjust the pH to 4 with 36% hydrochloric acid, stir and react at 40℃ for 10 min, filter, wash 3 times with deionized water, and dry in an oven at 70℃ for 10 min to obtain pretreated wear-resistant aggregate.

[0053] The hydroxyl groups generated by the hydrolysis of isocyanate silane can be chemically bonded to the hydroxyl groups on the surface of wear-resistant aggregate, thus grafting isocyanate silane onto the surface of wear-resistant aggregate.

[0054] Furthermore, the ratio of wear-resistant aggregate, isocyanate silane, ethanol, and deionized water is (0.3-0.7)g:(0.4-0.5)g:(15-25)mL:(6-10)mL.

[0055] B3. Add the monomer to N-methyl-2-pyrrolidone, stir until homogeneous, add trifluoroacetic acid to promote monomer dissolution, heat to 80℃, add pretreated wear-resistant aggregate, stir and react for 3 hours, filter, wash 3 times with deionized water, and dry in an oven at 70℃ for 10 minutes to obtain modified wear-resistant aggregate.

[0056] In this process, N-methyl-2-pyrrolidone is used as a solvent. The amino groups in the monomer can react with the isocyanates on the surface of the pretreated wear-resistant aggregate, allowing the monomer to be grafted onto the surface of the pretreated wear-resistant aggregate to form modified wear-resistant aggregate. The amino groups in the monomer of the modified wear-resistant aggregate can be bonded to the polyether-type TPU molecular chain through hydrogen bonds, so that the wear-resistant aggregate is uniformly dispersed in the polyether-type TPU composite material, avoiding the migration and precipitation of the wear-resistant aggregate and improving the wear resistance. In addition, the triazine ring structure in the monomer of the modified wear-resistant aggregate increases the stiffness of the polyether-type TPU composite material molecular chain and improves the mechanical properties.

[0057] Furthermore, the ratio of monomer, N-methyl-2-pyrrolidone, trifluoroacetic acid, and pretreated wear-resistant aggregate is (2-3)g:(15-25)mL:(0.1-0.3)mL:(0.3-0.7)g.

[0058] Furthermore, compared with the prior art, the present invention has the following beneficial effects: (1) In the technical solution of the present invention, the porous Co-Mn-O nanomaterial has excellent catalytic carbonization performance, thereby isolating oxygen and heat, and has good flame retardant performance. Moreover, the porous structure of Co-Mn-O nanomaterial can effectively adsorb harmful gases in the combustion process of polyether-type TPU composite material and inhibit the generation of smoke. In addition, Co-Mn-O nanomaterial can effectively catalyze the harmful gases released by polyether-type TPU composite material in the combustion process, converting the harmful gases into CO2, thereby inhibiting the generation of smoke and harmful gases.

[0059] (2) In the technical solution of the present invention, porous Co-Mn-O nanomaterials are synthesized in situ on the surface of hydroxylated calcium sulfate whiskers. The hydroxylated calcium sulfate whiskers, as carriers of Co-Mn-O nanomaterials, have excellent aspect ratios and can load more Co-Mn-O nanomaterials, thereby improving flame retardant performance. Furthermore, a rough surface is formed on the surface of the hydroxylated calcium sulfate whiskers, which increases the contact area between the composite flame retardant filler and the polyether-type TPU composite material, and mechanically interlocks with the polyether-type TPU composite material, thereby improving the bonding force between the composite flame retardant filler and the polyether-type TPU composite material. In addition, the random distribution of calcium sulfate whiskers in the composite flame retardant filler can absorb external stress and improve the impact strength of the polyether-type TPU composite material.

[0060] (3) In the technical solution of the present invention, the phytic acid-vanillin complex is used as a bio-based flame retardant. During the combustion process, it can act as a char-forming agent to generate an expanded char layer and isolate combustible gases. The organosilicon complex is grafted into the phytic acid-vanillin complex to improve the hydrophobic properties of the phytic acid-vanillin complex and avoid the high water solubility of phytic acid in the phytic acid-vanillin complex, which makes it easy to absorb water and affect the stability and service life of the polyether-type TPU composite material in a humid environment.

[0061] (4) In the technical solution of the present invention, the modified phytic acid-vanillin complex is adsorbed into the pores of Co-Mn-O nanomaterials in the modified calcium sulfate whiskers, forming an organic-inorganic flame retardant material with the modified calcium sulfate whiskers, thereby improving the flame retardant performance. Phytic acid and vanillin provide more carbon sources, which is beneficial to the catalytic carbonization effect of Co-Mn-O nanomaterials in the modified calcium sulfate whiskers. In addition, the organic flame retardant modified phytic acid-vanillin complex and the inorganic flame retardant modified calcium sulfate whiskers are precisely combined to improve the flame retardant performance. Furthermore, the hydrophobic chain contained in the organosilicon complex in the modified phytic acid-vanillin complex can combine with the hydrophobic segment of the polyether-type TPU composite material, thereby improving the compatibility between the composite flame retardant filler and the polyether-type TPU composite material, and thus improving the flame retardant performance and mechanical properties of the polyether-type TPU composite material.

[0062] (5) In the technical solution of the present invention, the monomer formed by the reaction of dicyandiamide and adiponitrile is grafted onto the surface of the pretreated wear-resistant aggregate through isocyanate silane to form a modified wear-resistant aggregate. The amino group contained in the monomer in the modified wear-resistant aggregate can be combined with the polyether type TPU molecular chain through hydrogen bonds, so that the wear-resistant aggregate is uniformly dispersed in the polyether type TPU composite material, avoiding the migration and precipitation of the wear-resistant aggregate, improving the wear resistance. In addition, the triazine ring structure contained in the monomer in the modified wear-resistant aggregate increases the stiffness of the polyether type TPU composite material molecular chain and improves the mechanical properties.

[0063] (6) In the technical solution of the present invention, the calcium phosphate oligomer is amorphous and gel-like. The calcium phosphate oligomer can combine with the molecular chain of polyether-type TPU composite material through hydrogen bonds to form a cross-linked network structure, which increases the cross-linking density of polyether-type TPU composite material, making the polyether-type TPU composite material more compact, increasing the dissipation effect of external force, having excellent resistance to dynamic friction, improving wear resistance, and the formed cross-linked network structure can encapsulate the modified wear-resistant aggregate and composite flame-retardant material in the polyether-type TPU composite material, improving the flame retardancy and high wear resistance of the polyether-type TPU composite material. Detailed Implementation

[0064] The technical solutions in the embodiments of the present invention have been clearly and completely described. 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.

[0065] The raw materials used in this invention embodiment are as follows: manganese sulfate hydrate, cobalt sulfate heptahydrate (purity 98%, Aladdin Biochemical Technology Co., Ltd.); dicyandiamide, adiponitrile, 2-methoxyethanol, trifluoroacetic acid (purity 99%, Shanghai Huayi Energy Chemical Co., Ltd.); 3-isocyanate-propyltrimethoxysilane (Shandong Lingxiao New Materials Co., Ltd.); N-methyl-2-pyrrolidone (Tianjin Kemeio Chemical Reagent Co., Ltd.); phosphoric acid, calcium chloride dihydrate (China National Pharmaceutical Group Co., Ltd.); 4-xylpyridine, vanillin (Shanghai Aladdin Biochemical Technology Co., Ltd., purity 99%); N,N-dicyclohexylcarbodiimide (Shanghai Aladdin Biochemical Technology Co., Ltd., purity 99%); N-aminoethyl-3-aminopropylmethyldimethoxysilane (Shanghai Guyan Industrial Co., Ltd., industrial grade); octamethylcyclotetrasiloxane (industrial grade, Hubei Kewode Chemical Co., Ltd.); phytic acid (Beijing Bio-Laibo Technology Co., Ltd.).

[0066] The compatibilizer is a hydroxyl-terminated polyether-modified silicone oil, preferably XIAMETER OFX-3667.

[0067] Calcium sulfate whiskers: 12-30μm in length and 0.5-2μm in diameter, Hubei Langbowan Biomedical Co., Ltd.

[0068] Hydroxylated calcium sulfate whiskers are prepared by the following steps: 2.6g of calcium sulfate whiskers are added to 100mL of 0.025mol / L trisodium phosphate solution, sonicated for 2min, stirred at room temperature to mix the solution evenly, filtered, washed 3 times with deionized water, and dried in an oven at 80℃ for 10min to obtain hydroxylated calcium sulfate whiskers.

[0069] The phytic acid-vanillin complex was prepared by the following steps: 7.3g vanillin was added to 40mL of ethanol and stirred until homogeneous. Then, 15g of phytic acid, 0.2g of 4g / L 4-xylenepyridine and 1.6g of N,N-dicyclohexylcarbodiimide were added and stirred at 130℃ for 3h. The ethanol was removed by concentration and evaporation, and the mixture was filtered, washed three times with deionized water, and dried in an oven at 80℃ for 10min to obtain the phytic acid-vanillin complex.

[0070] The organosilicon complex was prepared by the following steps: 4.5g of N-aminoethyl-3-aminopropylmethyldimethoxysilane and 5.6g of octamethylcyclotetrasiloxane were mixed and stirred evenly. 0.02g of sodium hydroxide, 10mL of deionized water and 0.5g of sodium dodecylbenzenesulfonate were added. The mixture was stirred at 80℃ for 5h and then cooled to 40℃. 36% hydrochloric acid was added to adjust the pH to neutral. The filtrate was collected by filtration to obtain the organosilicon complex.

[0071] Example 1: The composite flame-retardant filler was prepared by the following steps: A1. 1.32g of cobalt sulfate heptahydrate and 0.6g of manganese sulfate hydrate were added to 18mL of ethanol and 180mL of deionized water and stirred evenly. 2.6g of hydroxylated calcium sulfate whiskers were added and stirred for 10min. A sodium carbonate aqueous solution with a concentration of 0.5mol / L was added until the pH reached 8.5. The mixture was kept overnight, filtered, washed three times with deionized water, dried in an oven at 80℃ for 5h, placed in a muffle furnace, and calcined at 500℃ for 4h. After cooling to room temperature, modified calcium sulfate whiskers were obtained.

[0072] A2. Add 5g of phytic acid-vanillin complex to 80mL of deionized water and 20mL of ethanol, stir well, add 6.5g of organosilicon complex and 36% sodium hydroxide solution to adjust the pH to 4.5, heat to 80℃, stir and react for 1h, cool to room temperature, filter, wash 3 times with deionized water, and dry in an 80℃ oven for 10min to obtain modified phytic acid-vanillin complex.

[0073] A3. Add 2.5g of modified phytic acid-vanillin complex to 30mL of ethanol, stir, add 0.3g of modified calcium sulfate whiskers, apply negative pressure at -0.1MPa for 10min, heat to 85℃, stir until ethanol evaporates, wash 3 times with deionized water, and dry in an oven at 80℃ for 10min to obtain composite flame retardant filler.

[0074] Comparative Example 1 differs from Example 1 in that Co-Mn-O nanomaterials were not synthesized on the surface of calcium sulfate whiskers, while the remaining steps and raw materials were the same as in Example 1.

[0075] A1. Add 5g of phytic acid-vanillin complex to 80mL of deionized water and 20mL of ethanol, stir well, add 6.5g of organosilicon complex and 36% sodium hydroxide solution to adjust the pH to 4.5, heat to 80℃, stir and react for 1h, cool to room temperature, filter, wash 3 times with deionized water, and dry in an 80℃ oven for 10min to obtain modified phytic acid-vanillin complex.

[0076] A2. Add 2.5g of modified phytic acid-vanillin complex to 30mL of ethanol, stir, add 0.3g of calcium sulfate whiskers, heat to 85℃, and stir until the ethanol evaporates to obtain the composite flame retardant filler.

[0077] The difference between Comparative Example 2 and Example 1 is that the modified phytic acid-vanillin complex was not added, while the remaining steps and raw materials were the same as in Example 1.

[0078] 1.32 g of cobalt sulfate heptahydrate and 0.6 g of manganese sulfate hydrate were added to 18 mL of ethanol and 180 mL of deionized water and stirred until homogeneous. 2.6 g of hydroxylated calcium sulfate whiskers were added and stirred for 10 min. A 0.5 mol / L sodium carbonate aqueous solution was added until the pH reached 8.5. The mixture was kept overnight, filtered, washed three times with deionized water, dried in an oven at 80 °C for 5 h, placed in a muffle furnace, and calcined at 500 °C for 4 h. After cooling to room temperature, the composite flame-retardant filler was obtained.

[0079] Example 2 The composite wear-resistant aggregate was prepared by the following steps: B1. 5g dicyandiamide and 1.5g potassium hydroxide were added to 50mL 2-methoxyethanol and stirred at 200rpm for 10min. 2.7mL adiponitrile was added, the temperature was raised to 125℃, and the mixture was stirred for 6h. The mixture was filtered and washed with methanol to obtain the reaction product. The reaction product was dried in a vacuum oven at 80℃ and 10Pa for 24h to obtain the monomer.

[0080] B2. Add 0.5g of nano-zirconia and 0.45g of 3-isocyanate-propyltrimethoxysilane to 20mL of ethanol and 8mL of deionized water, stir well, adjust the pH to 4 with 36% hydrochloric acid, stir and react at 40℃ for 10min, filter, wash 3 times with deionized water, and dry in an oven at 70℃ for 10min to obtain pretreated wear-resistant aggregate.

[0081] B3. Add 2.5g of monomer to 20mL of N-methyl-2-pyrrolidone, stir well, add 0.2mL of trifluoroacetic acid to promote monomer dissolution, heat to 80℃, add 0.5g of pretreated wear-resistant aggregate, stir and react for 3h, filter, wash 3 times with deionized water, and dry in an oven at 70℃ for 10min to obtain modified wear-resistant aggregate.

[0082] B4. Add 2.6g of phosphoric acid to 30mL of ethanol and stir to obtain a phosphoric acid ethanol solution. Add 0.45g of calcium chloride dihydrate to 60mL of ethanol and stir at 25℃ for 30min. Add 6.1g of triethylamine and stir for 10min. Add 30mL of phosphoric acid ethanol solution and stir for 12h. Centrifuge at 8000rpm to collect the precipitate. Wash the precipitate three times with ethanol to remove triethylamine. Add the precipitate to 50mL of ethanol to form a stable emulsion to obtain calcium phosphate oligomer. Mix 30g of calcium phosphate oligomer with 2.5g of modified wear-resistant aggregate and stir evenly to obtain composite wear-resistant aggregate.

[0083] The difference between Comparative Example 3 and Example 2 is that no monomer was grafted onto the surface of the pretreated wear-resistant aggregate, while the remaining steps and raw materials were the same as in Example 2.

[0084] B1. Add 0.5g of nano-zirconia and 0.45g of 3-isocyanate-propyltrimethoxysilane to 20mL of ethanol and 8mL of deionized water, stir well, adjust the pH to 4 with 36% hydrochloric acid, stir and react at 40℃ for 10min, filter, wash 3 times with deionized water, and dry in an oven at 70℃ for 10min to obtain pretreated wear-resistant aggregate.

[0085] B2. Add 2.6g of phosphoric acid to 30mL of ethanol and stir to obtain a phosphoric acid ethanol solution. Add 0.45g of calcium chloride dihydrate to 60mL of ethanol and stir at 25℃ for 30min. Add 6.1g of triethylamine and stir for 10min. Add 30mL of phosphoric acid ethanol solution and stir to react for 12h. Centrifuge at 8000rpm to collect the precipitate. Wash the precipitate three times with ethanol to remove triethylamine. Add the precipitate to 50mL of ethanol to form a stable emulsion to obtain calcium phosphate oligomer. Mix 30g of calcium phosphate oligomer with 2.5g of pretreated wear-resistant aggregate and stir evenly to obtain composite wear-resistant aggregate.

[0086] The difference between Comparative Example 4 and Example 2 is that no calcium phosphate oligomer was added, while the remaining steps and raw materials were the same as in Example 2.

[0087] B1. Add 5g dicyandiamide and 1.5g potassium hydroxide to 50mL 2-methoxyethanol, stir at 200rpm for 10min, add 2.7mL adiponitrile, heat to 125℃, stir for 6h, filter the mixture and wash with methanol to obtain the reaction product, dry the reaction product in a vacuum oven at 80℃ and 10Pa for 24h to obtain the monomer.

[0088] B2. Add 0.5g of nano-zirconia and 0.45g of 3-isocyanate-propyltrimethoxysilane to 20mL of ethanol and 8mL of deionized water, stir well, adjust the pH to 4 with 36% hydrochloric acid, stir and react at 40℃ for 10min, filter, wash 3 times with deionized water, and dry in an oven at 70℃ for 10min to obtain pretreated wear-resistant aggregate.

[0089] B3. Add 2.5g of monomer to 20mL of N-methyl-2-pyrrolidone, stir well, add 0.2mL of trifluoroacetic acid to promote monomer dissolution, heat to 80℃, add 0.5g of pretreated wear-resistant aggregate, stir and react for 3h, filter, wash 3 times with deionized water, and dry in an oven at 70℃ for 10min to obtain composite wear-resistant aggregate.

[0090] Example 3: A polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material, comprising the following raw materials in parts by weight: 90 parts of polyether-type thermoplastic polyurethane elastomer, 10 parts of the composite flame-retardant filler prepared in Example 1, 10 parts of the composite wear-resistant aggregate prepared in Example 2, 1 part of compatibilizer, 0.1 parts of ultraviolet absorber UV-P, and 0.2 parts of antioxidant 300.

[0091] A method for preparing a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material includes the following steps: S1. Polyether-type thermoplastic polyurethane elastomer, composite flame-retardant filler, composite wear-resistant aggregate, compatibilizer, antibacterial agent, ultraviolet absorber UV-P, and antioxidant 300 are placed in a mixer and mixed at high speed at 40-60℃ for 3-5 minutes to obtain a mixture; S2. The mixture is placed in a twin-screw extruder, and after extrusion and granulation, a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material is obtained. The twin-screw extruder process is as follows: the temperature of the twin-screw feeding zone is 185℃, the temperature of the plasticizing zone is 195℃, the die head temperature is 205℃, and the screw speed is 80rpm.

[0092] Example 4: A polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material, comprising the following parts by weight of raw materials: 100 parts of polyether-type thermoplastic polyurethane elastomer, 13 parts of the composite flame-retardant filler prepared in Example 1, 11 parts of the composite wear-resistant aggregate prepared in Example 2, 1.5 parts of compatibilizer, 0.3 parts of ultraviolet absorber UV-O, and 0.4 parts of antioxidant 168.

[0093] A method for preparing a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material includes the following steps: S1. Polyether-type thermoplastic polyurethane elastomer, the composite flame-retardant filler prepared in Example 1, the composite wear-resistant aggregate prepared in Example 2, compatibilizer, ultraviolet absorber UV-O, and antioxidant 168 are placed in a mixer and mixed at high speed for 3-5 minutes at 40-60℃ to obtain a mixture; S2. The mixture is placed in a twin-screw extruder, and after extrusion and granulation, a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material is obtained. The twin-screw extruder process is as follows: the temperature of the twin-screw feeding zone is 185℃, the temperature of the plasticizing zone is 195℃, the die head temperature is 205℃, and the screw speed is 80 rpm.

[0094] Example 5: A polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material, comprising the following raw materials in parts by weight: 110 parts of polyether-type thermoplastic polyurethane elastomer, 15 parts of the composite flame-retardant filler prepared in Example 1, 12 parts of the composite wear-resistant aggregate prepared in Example 2, 2 parts of compatibilizer, 0.5 parts of ultraviolet absorber UV-9, and 0.6 parts of antioxidant 1010.

[0095] A method for preparing a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material includes the following steps: S1. Polyether-type thermoplastic polyurethane elastomer, the composite flame-retardant filler prepared in Example 1, the composite wear-resistant aggregate prepared in Example 2, compatibilizer, ultraviolet absorber UV-9, and antioxidant 1010 are placed in a mixer and mixed at high speed at 50°C for 4 minutes to obtain a mixture; S2. The mixture is placed in a twin-screw extruder, and after extrusion and granulation, a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material is obtained. The twin-screw extruder process is as follows: the temperature of the twin-screw feeding zone is 185°C, the temperature of the plasticizing zone is 195°C, the die head temperature is 205°C, and the screw speed is 80 rpm.

[0096] The difference between Comparative Example 5 and Example 4 is that the composite flame-retardant filler prepared in Example 1 is replaced with the substance prepared in Comparative Example 1, while the other steps are the same as in Example 4.

[0097] The difference between Comparative Example 6 and Example 4 is that the composite flame-retardant filler prepared in Example 1 is replaced with the substance prepared in Comparative Example 2, while the other steps are the same as in Example 4.

[0098] The difference between Comparative Example 7 and Example 4 is that the composite wear-resistant aggregate prepared in Example 2 is replaced with the substance prepared in Comparative Example 3, while the other steps are the same as in Example 4.

[0099] The difference between Comparative Example 8 and Example 4 is that the composite wear-resistant aggregate prepared in Example 2 is replaced with the substance prepared in Comparative Example 4, while the other steps are the same as in Example 4.

[0100] The performance of the polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite materials prepared in Examples 3-5 and Comparative Examples 5-8 was tested. Tensile strength and elongation at break were tested: The polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite materials prepared above were tested according to standard GB / T1040-2006. The tensile strength and elongation at break of the samples were measured using an electronic tensile testing machine. The tensile speed was 50 mm / min.

[0101] Hardness testing: The Shore hardness tester was used for testing. Three sets of data were tested for each sample, and the average value was taken.

[0102] Flame retardant performance testing: The flame retardant performance of the polyether-type ultra-wear-resistant halogen-free flame retardant TPU composite material prepared above was tested in accordance with GB / T2408-2008 and GBT2406.1-2008 "Determination of Combustion Behavior by Oxygen Index Method for Plastics".

[0103] Abrasion resistance testing: The abrasion resistance of the prepared polyether-type ultra-abrasion-resistant halogen-free flame-retardant TPU composite material was tested according to GB9867-88 standard. The abrasion amount (mg) was recorded using a rotary drum abrasion tester. The test results are shown in Table 1 below: Table 1

[0104] As can be seen from the data in Table 1, in Comparative Example 5, no Co-Mn-O nanomaterials were synthesized on the surface of calcium sulfate whiskers. When the composite flame-retardant filler was added to the polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material, its mechanical properties and flame-retardant properties decreased. This may be because Co-Mn-O nanomaterials have good flame-retardant properties, and the synthesis of Co-Mn-O nanomaterials on the surface of calcium sulfate whiskers increases the contact area between the composite flame-retardant filler and the polyether-type TPU composite material, and mechanically interlocks with the polyether-type TPU composite material, which can exert better mechanical properties. However, the calcium sulfate whisker surface lacks Co-Mn-O nanomaterials, so this effect cannot be achieved, and therefore the mechanical properties and flame-retardant properties decrease. Comparative Example 6, which did not contain the modified phytic acid-vanillin complex, showed a decrease in mechanical and flame-retardant properties when the composite flame-retardant filler was added to the polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material. This may be because the modified phytic acid-vanillin complex adsorbs into the pores of the Co-Mn-O nanomaterials in the modified calcium sulfate whiskers, forming an organic-inorganic flame-retardant material with the modified calcium sulfate whiskers, thus improving the flame-retardant properties. Furthermore, the modified phytic acid-vanillin complex can bind to the hydrophobic segments of the polyether-type TPU composite material, improving the flame-retardant and mechanical properties of the polyether-type TPU composite material. However, the modified calcium sulfate whiskers lack bio-based flame retardants and the modified phytic acid-vanillin complex, thus failing to achieve this effect, resulting in a decrease in mechanical and flame-retardant properties. In Comparative Example 7, no monomers were grafted onto the surface of the pretreated wear-resistant aggregate. When the composite wear-resistant aggregate prepared was added to the polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material, its wear resistance and mechanical properties decreased. This may be because when monomers are grafted onto the surface of the pretreated wear-resistant aggregate, the amino groups contained in the monomers can bind with the polyether-type TPU molecular chains through hydrogen bonds, making the wear-resistant aggregates uniformly dispersed in the polyether-type TPU composite material and improving wear resistance. In addition, the triazine ring structure contained in the monomers increases the stiffness of the polyether-type TPU composite material molecular chains and improves mechanical properties. However, the composite wear-resistant aggregate lacks monomers and cannot achieve this effect, thus resulting in a decrease in wear resistance and mechanical properties. Comparative Example 8, which did not contain calcium phosphate oligomers, showed a decrease in wear resistance and mechanical properties when the composite wear-resistant aggregate was added to a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material. This may be because calcium phosphate oligomers can bond with the molecular chains of the polyether-type TPU composite material through hydrogen bonds, making the polyether-type TPU composite material more compact and increasing the dissipation effect of external forces, resulting in excellent wear resistance. Furthermore, it can encapsulate modified wear-resistant aggregates and composite flame-retardant materials in the polyether-type TPU composite material, improving the flame retardancy and high wear resistance of the polyether-type TPU composite material. However, the composite wear-resistant aggregate lacks calcium phosphate oligomers, failing to achieve this effect, thus resulting in a decrease in wear resistance and mechanical properties.

[0105] The data in Table 1 show that the polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite materials prepared in Examples 3-5 meet the requirements of the test performance, while the polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite materials prepared in Comparative Examples 5-8 do not meet the performance requirements. This indicates that the polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite materials prepared in this invention have good mechanical properties, flame retardant properties and wear resistance.

[0106] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0107] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material, characterized in that, The raw materials include the following parts by weight: 90-110 parts of polyether-type thermoplastic polyurethane elastomer, 10-15 parts of composite flame retardant filler, 10-12 parts of composite wear-resistant aggregate, 1-2 parts of compatibilizer, 0.1-0.5 parts of ultraviolet absorber, and 0.2-0.6 parts of antioxidant; The composite flame-retardant filler is prepared by reacting phytic acid, vanillin, and organosilicon complex, and then mixing it with modified calcium sulfate whiskers. The modified calcium sulfate whiskers are prepared by mixing hydroxylated calcium sulfate whiskers with a cobalt source and a manganese source, followed by calcination. The composite wear-resistant aggregate is prepared by mixing modified wear-resistant aggregate and calcium phosphate oligomer. The modified wear-resistant aggregate is prepared by reacting dicyandiamide and adiponitrile to form a monomer, and then mixing and reacting it with wear-resistant aggregate surface-treated with isocyanate silane. The wear-resistant aggregate is selected from nano-zirconia.

2. The polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material according to claim 1, characterized in that, The hydroxylated calcium sulfate whiskers have a length of 12-26 μm and a diameter of 0.5-1.5 μm.

3. The polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material according to claim 1, characterized in that, The manganese source is selected from manganese sulfate hydrate or manganese nitrate; the cobalt source is selected from cobalt sulfate heptahydrate or cobalt nitrate; the calcination temperature is 450-550℃, and the calcination time is 3-5h.

4. The polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material according to claim 1, characterized in that, The hydroxylated calcium sulfate whiskers are prepared by the following steps: calcium sulfate whiskers are added to a 0.02-0.03 mol / L trisodium phosphate solution, ultrasonically treated, stirred evenly, filtered, washed, and dried to obtain hydroxylated calcium sulfate whiskers.

5. The polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material according to claim 1, characterized in that, The isocyanate silane is selected from 3-isocyanatopropyltrimethoxysilane or isocyanatopropyltriethoxysilane.

6. The polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material according to claim 1, characterized in that, The compatibilizer is a hydroxyl-terminated polyether-modified silicone oil, preferably XIAMETER OFX-3667; the antioxidant is selected from any one of antioxidant 300, antioxidant 168, antioxidant 1010, and antioxidant 626.

7. The polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material according to claim 1, characterized in that, The ultraviolet absorber is selected from any one of ultraviolet absorbers UV-P, UV-O, UV-9, and UV-531.

8. A method for preparing a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Place the polyether-type thermoplastic polyurethane elastomer, composite flame-retardant filler, composite wear-resistant aggregate, compatibilizer, antibacterial agent, ultraviolet absorber, and antioxidant in a mixer and mix at high speed for 3-5 minutes at 40-60℃ to obtain a mixture; S2. The mixture is placed in a twin-screw extruder and extruded and granulated to obtain a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material.

9. The preparation method of a polyether-type ultra-wear-resistant halogen-free flame-retardant TPU composite material according to claim 8, characterized in that, The twin-screw extruder process is as follows: the temperature of the twin-screw feeding zone is 180-190℃, the temperature of the plasticizing zone is 190-200℃, the temperature of the die head is 200-210℃, and the screw speed is 70-90 rpm.

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