Anti-breaking high-strength special belt for smoke machine and preparation method thereof

Abstract

This invention relates to the field of transportation equipment technology, specifically to a high-strength, break-resistant conveyor belt for a tobacco machine and its preparation method. The invention first grafts acrylic acid onto low-density polyethylene, then reacts it with a polyurethane prepolymer to prepare a compatibilizer; subsequently, it reacts 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to prepare a flame retardant; the polyurethane prepolymer is reacted with dihydroxy-terminated polydimethylsiloxane, chain extended, and then the flame retardant is added for end-capping and curing to obtain a silicon-containing flame-retardant polyurethane. High-density polyethylene and the silicon-containing flame-retardant polyurethane are mixed, and a compatibilizer, carbon nanotubes, light calcium carbonate, and an antioxidant are added. After melting and stirring, the mixture is cooled and dicumyl peroxide is added for crosslinking. Following injection molding, demolding, cutting, trimming, edge sealing, and polishing, the finished product is obtained.

Description

Technical Field

[0001] This invention relates to the field of transportation equipment technology, specifically to a high-strength, anti-breakage belt for tobacco machinery and its preparation method. Background Technology

[0002] The tobacco production process requires the separate processing of materials such as tobacco leaves, shredded tobacco, and tobacco stems, often involving the transportation of these materials. Tobacco leaves themselves have a complex composition, containing intricate compounds, and different formulas of flavorings and fragrances are added during production. As a result, impurities often remain on the surface of the conveyor belt, leading to an unpleasant taste in the tobacco product.

[0003] The conveyor belts currently used in the tobacco industry are generally made of polyvinyl chloride (PVC), polyethylene (PE), or thermoplastic polyurethane (TPU) elastomers. PVC belts have high surface energy, leading to significant material adhesion; PE belts have low surface hardness, poor wear resistance, and high porosity in their film, allowing oil stains to easily penetrate over time; while TPU elastomer belts have high mechanical strength and wear resistance, but a relatively high coefficient of friction. Based on these technical problems and the characteristics of different materials, there is a need to develop a high-strength, break-resistant conveyor belt specifically for tobacco machinery. Summary of the Invention

[0004] The purpose of this invention is to provide a high-strength, anti-breakage belt for smoke hoods and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high-strength, break-resistant belt for a range hood and its preparation method, comprising the following steps:

[0006] High-density polyethylene and silicone-containing flame-retardant polyurethane are mixed to obtain a mixture. The mixture, compatibilizer, carbon nanotubes, light calcium carbonate, and antioxidant are melted and stirred at 200~230℃, cooled to 110~120℃, and dicumyl peroxide is added for crosslinking reaction for 120~130s. After injection molding, demolding, cutting, trimming, edge sealing, and polishing, the finished product is obtained.

[0007] Furthermore, in the mixture, the content of each component, by weight, is 85-90% high-density polyethylene and 10-15% silicone-containing flame-retardant polyurethane.

[0008] Furthermore, the dosage of each component, by weight, is as follows: 100 parts of mixed materials, 8-12 parts of compatibilizer, 5-9 parts of carbon nanotubes, 3-5 parts of light calcium carbonate, and 2-3 parts of antioxidant.

[0009] Furthermore, the method for preparing the compatibilizer includes the following steps:

[0010] Step 1:

[0011] Toluene diisocyanate and polypropylene glycol 1000 were mixed, and dibutyltin dilaurate was added as a catalyst. The mixture was stirred and reacted under nitrogen protection at 75-90°C to obtain a polyurethane prepolymer.

[0012] Step 2:

[0013] Low-density polyethylene and xylene were mixed and heated until the polyethylene dissolved. Acrylic acid and benzoyl peroxide were added and reacted. The product was poured into anhydrous ethanol, the mother liquor was filtered off, the precipitate was washed in anhydrous ethanol and dried under vacuum to obtain polyethylene grafted with acrylic acid.

[0014] Step 3:

[0015] Polyethylene grafted with acrylic acid and polyurethane prepolymer were mixed and heated to 90-100°C under nitrogen protection. After reacting for 10-12 hours, the temperature was lowered to 60-70°C. Unreacted isocyanate groups were capped with anhydrous ethanol. Ungrafted polyurethane prepolymer was removed from the reactants with N,N-dimethylformamide. The mixture was then vacuum dried to obtain a compatibilizer.

[0016] Further, in step 1, toluene diisocyanate and polypropylene glycol 1000 react at a molar ratio of 2:1.

[0017] Furthermore, in step 2, the weight ratio of benzoyl peroxide, acrylic acid, and polyethylene is (0.5~0.8):(12~15):100.

[0018] Furthermore, in step 3, the mass ratio of polyethylene grafted acrylic acid to polyurethane prepolymer is 100:(8~10).

[0019] Furthermore, the preparation method of silicone-containing flame-retardant polyurethane includes the following steps:

[0020] S1: Mix toluene diisocyanate and polypropylene glycol 1000, add the catalyst dibutyltin dilaurate, and stir the reaction under nitrogen protection at 75~90℃ to obtain polyurethane prepolymer;

[0021] S2: 3-Amino-1,2,4-triazole and hydroxycitronellol are dispersed in anhydrous ethanol and refluxed for 8-10 hours. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added and reflux is continued for another 8-9 hours. After the reaction is completed, the mixture is allowed to cool naturally and the precipitate is washed by centrifugation with anhydrous ethanol and then dried under vacuum to obtain the flame retardant.

[0022] S3: Mix 100 parts of polyurethane prepolymer and 10-15 parts of dihydroxy-terminated polydimethylsiloxane, use dibutyltin dilaurate as catalyst, heat to 70-90℃ under nitrogen protection, keep the temperature for 2-3 hours, add 1,4-butanediol, chain extension reaction for 1-2 hours; continue to add flame retardant, end-capping reaction for 0.5-1 hours, and cure to obtain silicone-containing flame-retardant polyurethane.

[0023] Further, in S1, toluene diisocyanate and polypropylene glycol 1000 react in a molar ratio of 2:1; in S2, the molar ratio of 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1; in S3, the amounts of each component, by weight, are: 100 parts polyurethane prepolymer, 10-15 parts dihydroxy-terminated polydimethylsiloxane, 2-3 parts 1,4-butanediol, and 8-10 parts flame retardant.

[0024] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention provides a method for preparing a high-strength, break-resistant belt specifically for range hoods. High-density polyethylene and silicon-containing flame-retardant polyurethane are mixed, and a compatibilizer, carbon nanotubes, light calcium carbonate, and an antioxidant are added. After melting and stirring, the mixture is cooled and then cross-linked with dicumyl peroxide. Following injection molding, demolding, cutting, trimming, edge sealing, and polishing, the finished product is obtained. By blending low-friction polyethylene with high-tensile-strength polyurethane, a high-performance composite material is obtained, which can be used to prepare a high-strength, break-resistant belt specifically for range hoods.

[0025] The compatibilizer is obtained by grafting acrylic acid onto low-density polyethylene, followed by reaction of the carboxyl groups with the isocyanate groups on the polyurethane prepolymer. The addition of the compatibilizer improves the compatibility between polyethylene and silicone-containing flame-retardant polyurethane, enabling cross-linking and forming a network structure. This network structure prevents small-molecule inorganic materials from migrating to the material surface. In preparing the silicone-containing flame-retardant polyurethane, flame retardants with hydroxyl-terminated groups are first prepared using 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide as raw materials to end-cap the polyurethane. Simultaneously, organosilicon segments are introduced into the polyurethane. On one hand, organosilicon can synergistically enhance the flame-retardant properties with the flame retardant; on the other hand, organosilicon can improve the toughness of the material, preventing breakage due to external forces during use.

[0026] Furthermore, it should be noted that when the amount of silicone-containing flame-retardant polyurethane used is too high, the compatibility of the blend system deteriorates, thus affecting the performance of the product. Therefore, the belt with the best performance is prepared by mixing 85-90% high-density polyethylene and 10-15% silicone-containing flame-retardant polyurethane by weight. Detailed Implementation

[0027] 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] The materials used in this invention and their sources are as follows: low-density polyethylene is from Shanghai Petrochemical, model LF5600; high-density polyethylene is from Dushanzi Petrochemical, model DMDA-8008; dihydroxy-terminated polydimethylsiloxane (Mn=1000) is from Shanghai Tiger Polymer Technology Co., Ltd.; the average particle size of light calcium carbonate is 0.01~0.1μm; the average diameter of carbon nanotubes is 10~25nm; and the antioxidant is antioxidant 4020.

[0029] Example 1: A high-strength, anti-breakage belt for a range hood and its preparation method, comprising the following steps:

[0030] Step 1:

[0031] Toluene diisocyanate and polypropylene glycol 1000 were mixed, and dibutyltin dilaurate was added as a catalyst. The mixture was stirred and reacted under nitrogen protection at 75°C to obtain a polyurethane prepolymer. Toluene diisocyanate and polypropylene glycol 1000 were reacted in a molar ratio of 2:1.

[0032] Step 2:

[0033] S21: Mix low-density polyethylene and xylene, heat until polyethylene dissolves, add acrylic acid and benzoyl peroxide to react, pour the product into anhydrous ethanol, filter off the mother liquor, soak the precipitate in anhydrous ethanol to wash, and vacuum dry to obtain polyethylene grafted with acrylic acid; wherein, the weight ratio of benzoyl peroxide, acrylic acid and polyethylene is 0.5:15:100.

[0034] S22: Polyethylene grafted with acrylic acid and polyurethane prepolymer are mixed and heated to 90°C under nitrogen protection. After reacting for 10 hours, the temperature is lowered to 60°C, and the unreacted isocyanate groups are capped with anhydrous ethanol. The ungrafted polyurethane prepolymer in the reactants is removed with N,N-dimethylformamide, and the mixture is dried under vacuum to obtain a compatibilizer. The mass ratio of polyethylene grafted with acrylic acid to polyurethane prepolymer is 100:8.

[0035] Step 3:

[0036] S31: 3-Amino-1,2,4-triazole and hydroxycitronellol were dispersed in anhydrous ethanol and refluxed for 8 hours. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added and refluxed for another 8 hours. After the reaction was completed, the mixture was allowed to cool naturally, and the precipitate was washed by centrifugation with anhydrous ethanol and dried under vacuum to obtain the flame retardant. The molar ratio of 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1:1.

[0037] S32: Mix 100 kg of polyurethane prepolymer and 14 kg of dihydroxy-terminated polydimethylsiloxane, using dibutyltin dilaurate as a catalyst, heat to 70 °C under nitrogen protection, and maintain the temperature for 2 h. Add 2.5 kg of 1,4-butanediol and perform chain extension reaction for 1 h. Continue to add 10 kg of flame retardant and perform end-capping reaction for 0.5 h. After curing, obtain silicone-containing flame-retardant polyurethane.

[0038] Step 4:

[0039] By weight percentage, 85% high-density polyethylene and 15% silicone flame-retardant polyurethane are mixed to obtain a mixture. 100 kg of the mixture, 12 kg of compatibilizer, 8 kg of carbon nanotubes, 4.5 kg of light calcium carbonate, and 2.8 kg of antioxidant are melted and stirred at 200°C, cooled to 110°C, and 1 kg of dicumyl peroxide is added for a crosslinking reaction of 120 s. After injection molding, demolding, cutting, slicing, edge sealing, and polishing, the finished product is obtained.

[0040] Example 2: A high-strength, break-resistant belt for a range hood and its preparation method, comprising the following steps:

[0041] Step 1:

[0042] Toluene diisocyanate and polypropylene glycol 1000 were mixed, and dibutyltin dilaurate was added as a catalyst. The mixture was stirred and reacted under nitrogen protection at 80°C to obtain a polyurethane prepolymer. Toluene diisocyanate and polypropylene glycol 1000 were reacted in a molar ratio of 2:1.

[0043] Step 2:

[0044] S21: Mix low-density polyethylene and xylene, heat until polyethylene dissolves, add acrylic acid and benzoyl peroxide to react, pour the product into anhydrous ethanol, filter off the mother liquor, soak the precipitate in anhydrous ethanol to wash, and vacuum dry to obtain polyethylene grafted with acrylic acid; wherein, the weight ratio of benzoyl peroxide, acrylic acid and polyethylene is 0.5:15:100.

[0045] S22: Polyethylene grafted with acrylic acid and polyurethane prepolymer are mixed and heated to 95°C under nitrogen protection. After reacting for 11 hours, the temperature is lowered to 65°C, and the unreacted isocyanate groups are capped with anhydrous ethanol. The ungrafted polyurethane prepolymer in the reactants is removed with N,N-dimethylformamide, and the mixture is dried under vacuum to obtain a compatibilizer. The mass ratio of polyethylene grafted with acrylic acid to polyurethane prepolymer is 100:8.

[0046] Step 3:

[0047] S31: 3-Amino-1,2,4-triazole and hydroxycitronellol were dispersed in anhydrous ethanol and refluxed for 9 h. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added and refluxed for another 8.5 h. After the reaction was completed, the mixture was allowed to cool naturally, and the precipitate was washed by centrifugation with anhydrous ethanol and dried under vacuum to obtain the flame retardant. The molar ratio of 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1:1.

[0048] S32: Mix 100 kg of polyurethane prepolymer and 14 kg of dihydroxy-terminated polydimethylsiloxane, using dibutyltin dilaurate as a catalyst, heat to 80 °C under nitrogen protection, and maintain the temperature for 2.5 h. Add 2.5 kg of 1,4-butanediol and perform chain extension reaction for 1.5 h. Continue to add 10 kg of flame retardant and perform end-capping reaction for 0.5 h. After curing, obtain silicone-containing flame-retardant polyurethane.

[0049] Step 4:

[0050] By weight percentage, 88% high-density polyethylene and 12% silicone flame-retardant polyurethane are mixed to obtain a mixture. 100 kg of the mixture, 12 kg of compatibilizer, 8 kg of carbon nanotubes, 4.5 kg of light calcium carbonate, and 2.8 kg of antioxidant are melted and stirred at 210°C, cooled to 115°C, and 1 kg of dicumyl peroxide is added for a crosslinking reaction of 125 s. After injection molding, demolding, cutting, slicing, edge sealing, and polishing, the finished product is obtained.

[0051] Example 3: A high-strength, break-resistant conveyor belt for a range hood and its preparation method, comprising the following steps:

[0052] Step 1:

[0053] Toluene diisocyanate and polypropylene glycol 1000 were mixed, and dibutyltin dilaurate was added as a catalyst. The mixture was stirred and reacted under nitrogen protection at 90°C to obtain a polyurethane prepolymer. Toluene diisocyanate and polypropylene glycol 1000 were reacted in a molar ratio of 2:1.

[0054] Step 2:

[0055] S21: Mix low-density polyethylene and xylene, heat until polyethylene dissolves, add acrylic acid and benzoyl peroxide to react, pour the product into anhydrous ethanol, filter off the mother liquor, soak the precipitate in anhydrous ethanol to wash, and vacuum dry to obtain polyethylene grafted with acrylic acid; wherein, the weight ratio of benzoyl peroxide, acrylic acid and polyethylene is 0.5:15:100.

[0056] S22: Polyethylene grafted with acrylic acid and polyurethane prepolymer are mixed and heated to 100°C under nitrogen protection. After reacting for 12 hours, the temperature is lowered to 70°C, and the unreacted isocyanate groups are capped with anhydrous ethanol. The ungrafted polyurethane prepolymer in the reactants is removed with N,N-dimethylformamide, and the mixture is dried under vacuum to obtain a compatibilizer. The mass ratio of polyethylene grafted with acrylic acid to polyurethane prepolymer is 100:8.

[0057] Step 3:

[0058] S31: 3-Amino-1,2,4-triazole and hydroxycitronellol were dispersed in anhydrous ethanol and refluxed for 10 h. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added and refluxed for another 9 h. After the reaction was completed, the mixture was allowed to cool naturally, and the precipitate was washed by centrifugation with anhydrous ethanol and dried under vacuum to obtain the flame retardant. The molar ratio of 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1:1.

[0059] S32: Mix 100 kg of polyurethane prepolymer and 14 kg of dihydroxy-terminated polydimethylsiloxane, use dibutyltin dilaurate as catalyst, heat to 90 °C under nitrogen protection, keep the temperature for 3 h, add 2.5 kg of 1,4-butanediol, chain extension reaction for 2 h; continue to add 10 kg of flame retardant, end-capping reaction for 1 h, and cure to obtain silicone-containing flame retardant polyurethane;

[0060] Step 4:

[0061] By weight percentage, 90% high-density polyethylene and 10% silicone flame-retardant polyurethane are mixed to obtain a mixture. 100 kg of the mixture, 12 kg of compatibilizer, 8 kg of carbon nanotubes, 4.5 kg of light calcium carbonate, and 2.8 kg of antioxidant are melted and stirred at 230°C, cooled to 120°C, and 1 kg of dicumyl peroxide is added for a crosslinking reaction for 130 seconds. After injection molding, demolding, cutting, slicing, edge sealing, and polishing, the finished product is obtained.

[0062] Comparative Example 1: No compatibilizer was added, and all other parameters were the same as in Example 1.

[0063] Step 1:

[0064] Toluene diisocyanate and polypropylene glycol 1000 were mixed, and dibutyltin dilaurate was added as a catalyst. The mixture was stirred and reacted under nitrogen protection at 75°C to obtain a polyurethane prepolymer. Toluene diisocyanate and polypropylene glycol 1000 were reacted in a molar ratio of 2:1.

[0065] Step 2:

[0066] S21: 3-Amino-1,2,4-triazole and hydroxycitronellol were dispersed in anhydrous ethanol and refluxed for 8 hours. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added and refluxed for another 8 hours. After the reaction was completed, the mixture was allowed to cool naturally, and the precipitate was washed by centrifugation with anhydrous ethanol and dried under vacuum to obtain the flame retardant. The molar ratio of 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1:1.

[0067] S22: Mix 100 kg of polyurethane prepolymer and 14 kg of dihydroxy-terminated polydimethylsiloxane, use dibutyltin dilaurate as catalyst, heat to 70 °C under nitrogen protection, keep the temperature for 2 h, add 2.5 kg of 1,4-butanediol, chain extension reaction for 1 h; continue to add 10 kg of flame retardant, end-capping reaction for 0.5 h, and cure to obtain silicone-containing flame-retardant polyurethane;

[0068] Step 3:

[0069] By weight percentage, 85% high-density polyethylene and 15% silicone flame-retardant polyurethane are mixed to obtain a mixture. 100 kg of the mixture, 12 kg of compatibilizer, 8 kg of carbon nanotubes, 4.5 kg of light calcium carbonate, and 2.8 kg of antioxidant are melted and stirred at 200°C, cooled to 110°C, and 1 kg of dicumyl peroxide is added for a crosslinking reaction of 120 s. After injection molding, demolding, cutting, slicing, edge sealing, and polishing, the finished product is obtained.

[0070] Comparative Example 2: Conventional polyurethane was used instead of silicone-containing flame-retardant polyurethane, and the remaining parameters were the same as in Example 2.

[0071] Step 1:

[0072] Toluene diisocyanate and polypropylene glycol 1000 were mixed, and dibutyltin dilaurate was added as a catalyst. The mixture was stirred and reacted under nitrogen protection at 80°C to obtain a polyurethane prepolymer. Toluene diisocyanate and polypropylene glycol 1000 were reacted in a molar ratio of 2:1.

[0073] Step 2:

[0074] S21: Mix low-density polyethylene and xylene, heat until polyethylene dissolves, add acrylic acid and benzoyl peroxide to react, pour the product into anhydrous ethanol, filter off the mother liquor, soak the precipitate in anhydrous ethanol to wash, and vacuum dry to obtain polyethylene grafted with acrylic acid; wherein, the weight ratio of benzoyl peroxide, acrylic acid and polyethylene is 0.5:15:100.

[0075] S22: Polyethylene grafted with acrylic acid and polyurethane prepolymer are mixed and heated to 95°C under nitrogen protection. After reacting for 11 hours, the temperature is lowered to 65°C, and the unreacted isocyanate groups are capped with anhydrous ethanol. The ungrafted polyurethane prepolymer in the reactants is removed with N,N-dimethylformamide, and the mixture is dried under vacuum to obtain a compatibilizer. The mass ratio of polyethylene grafted with acrylic acid to polyurethane prepolymer is 100:8.

[0076] Step 3:

[0077] Using dibutyltin dilaurate as a catalyst, under nitrogen protection and at 80°C, 100 kg of polyurethane prepolymer and 8.6 kg of 1,4-butanediol were mixed and subjected to a chain extension reaction for 1.5 h; then 10 kg of ethanol was added to end-cap the reaction for 0.5 h, and the mixture was aged to obtain a silicone-containing flame-retardant polyurethane.

[0078] Step 4:

[0079] By weight percentage, 88% high-density polyethylene and 12% silicone flame-retardant polyurethane are mixed to obtain a mixture. 100 kg of the mixture, 12 kg of compatibilizer, 8 kg of carbon nanotubes, 4.5 kg of light calcium carbonate, and 2.8 kg of antioxidant are melted and stirred at 210°C, cooled to 115°C, and 1 kg of dicumyl peroxide is added for a crosslinking reaction of 125 s. After injection molding, demolding, cutting, slicing, edge sealing, and polishing, the finished product is obtained.

[0080] Comparative Example 3: The amount of silicone flame-retardant polyurethane was increased, while the other parameters were the same as in Example 3.

[0081] Step 1:

[0082] Toluene diisocyanate and polypropylene glycol 1000 were mixed, and dibutyltin dilaurate was added as a catalyst. The mixture was stirred and reacted under nitrogen protection at 90°C to obtain a polyurethane prepolymer. Toluene diisocyanate and polypropylene glycol 1000 were reacted in a molar ratio of 2:1.

[0083] Step 2:

[0084] S21: Mix low-density polyethylene and xylene, heat until polyethylene dissolves, add acrylic acid and benzoyl peroxide to react, pour the product into anhydrous ethanol, filter off the mother liquor, soak the precipitate in anhydrous ethanol to wash, and vacuum dry to obtain polyethylene grafted with acrylic acid; wherein, the weight ratio of benzoyl peroxide, acrylic acid and polyethylene is 0.5:15:100.

[0085] S22: Polyethylene grafted with acrylic acid and polyurethane prepolymer are mixed and heated to 100°C under nitrogen protection. After reacting for 12 hours, the temperature is lowered to 70°C, and the unreacted isocyanate groups are capped with anhydrous ethanol. The ungrafted polyurethane prepolymer in the reactants is removed with N,N-dimethylformamide, and the mixture is dried under vacuum to obtain a compatibilizer. The mass ratio of polyethylene grafted with acrylic acid to polyurethane prepolymer is 100:8.

[0086] Step 3:

[0087] S31: 3-Amino-1,2,4-triazole and hydroxycitronellol were dispersed in anhydrous ethanol and refluxed for 10 h. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added and refluxed for another 9 h. After the reaction was completed, the mixture was allowed to cool naturally, and the precipitate was washed by centrifugation with anhydrous ethanol and dried under vacuum to obtain the flame retardant. The molar ratio of 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1:1.

[0088] S32: Mix 100 kg of polyurethane prepolymer and 14 kg of dihydroxy-terminated polydimethylsiloxane, use dibutyltin dilaurate as catalyst, heat to 90 °C under nitrogen protection, keep the temperature for 3 h, add 2.5 kg of 1,4-butanediol, chain extension reaction for 2 h; continue to add 10 kg of flame retardant, end-capping reaction for 1 h, and cure to obtain silicone-containing flame retardant polyurethane;

[0089] Step 4:

[0090] By weight percentage, 80% high-density polyethylene and 20% silicone flame-retardant polyurethane are mixed to obtain a mixture. 100 kg of the mixture, 12 kg of compatibilizer, 8 kg of carbon nanotubes, 4.5 kg of light calcium carbonate, and 2.8 kg of antioxidant are melted and stirred at 230°C, cooled to 120°C, and 1 kg of dicumyl peroxide is added for a crosslinking reaction for 130 seconds. After injection molding, demolding, cutting, slicing, edge sealing, and polishing, the finished product is obtained.

[0091] Experiment: The performance of the belts prepared in Examples 1-3 and Comparative Examples 1-3 was tested.

[0092] Flame retardant performance: tested by limiting oxygen index.

[0093] Tensile strength: Tested according to standard GB / T1040-2006. The sample is dumbbell-shaped, the tensile rate is 50 mm / min, the gauge length is 25 mm, and the tensile strength and elongation at break are tested.

[0094] Friction coefficient: Tested using a friction coefficient / peel tester (FPT-F1, Jinan Langguang Electromechanical Technology Co., Ltd.).

[0095] The experimental results are shown in Table 1.

[0096] Table 1. Performance Test Results of Belts for Range Hoods

[0097]

[0098] Conclusions: Data from Examples 1-3 and Comparative Examples 1-3 show that the special belt for smoke hoods prepared by this invention has good performance. Data from Examples and Comparative Example 1 show that the compatibilizer improves the compatibility between polyethylene and silicone-containing flame-retardant polyurethane, thereby improving product performance. Data from Examples 2 and Comparative Example 2 show that, compared with conventional polyurethane, silicone-containing flame-retardant polyurethane improves flame retardant performance while reducing the coefficient of friction and improving wear resistance. Data from Examples 3 and Comparative Example 3 show that increasing the amount of silicone-containing flame-retardant polyurethane reduces the mechanical properties and coefficient of friction of the product.

[0099] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, anti-breaking special belt for a smoke machine, characterized by: The process includes the following steps: mixing high-density polyethylene and silicone-containing flame-retardant polyurethane to obtain a mixture; melting and stirring the mixture, compatibilizer, carbon nanotubes, light calcium carbonate, and antioxidant at 200-230°C, cooling to 110-120°C, adding dicumyl peroxide for a crosslinking reaction for 120-130 seconds, and then injection molding, demolding, cutting, trimming, edge sealing, and polishing to obtain the finished product. The preparation method of the compatibilizer includes the following steps: Step 1: Mix toluene diisocyanate and polypropylene glycol 1000, add the catalyst dibutyltin dilaurate, and stir the reaction under nitrogen protection at 75~90℃ to obtain polyurethane prepolymer; Step 2: Mix low-density polyethylene and xylene, heat until the polyethylene dissolves, add acrylic acid and benzoyl peroxide to react, pour the product into anhydrous ethanol, filter off the mother liquor, soak the precipitate in anhydrous ethanol to wash, and vacuum dry to obtain polyethylene grafted with acrylic acid. Step 3: Mix polyethylene grafted with acrylic acid and polyurethane prepolymer, heat to 90~100℃ under nitrogen protection, react for 10~12h, then cool to 60~70℃, end-cap the unreacted isocyanate groups with anhydrous ethanol, remove the ungrafted polyurethane prepolymer from the reactants with N,N-dimethylformamide, and vacuum dry to obtain the compatibilizer. A method for preparing silicone flame-retardant polyurethane includes the following steps: S1: Toluene diisocyanate and polypropylene glycol 1000 are mixed, and dibutyltin dilaurate is added as a catalyst. The mixture is stirred and reacted under nitrogen protection at 75~90°C to obtain a polyurethane prepolymer. S2: 3-Amino-1,2,4-triazole and hydroxycitronellol are dispersed in anhydrous ethanol and refluxed for 8-10 hours. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added and reflux is continued for another 8-9 hours. After the reaction is completed, the mixture is allowed to cool naturally and the precipitate is washed by centrifugation with anhydrous ethanol and then dried under vacuum to obtain the flame retardant. S3: Mix polyurethane prepolymer and dihydroxy-terminated polydimethylsiloxane, use dibutyltin dilaurate as catalyst, heat to 70~90℃ under nitrogen protection, keep the reaction at this temperature for 2~3h, add 1,4-butanediol, chain extension reaction for 1~2h; continue to add flame retardant, end-capping reaction for 0.5~1h, and cure to obtain silicone-containing flame retardant polyurethane.

2. The method for preparing a high-strength, anti-breakage belt for a smoke machine according to claim 1, characterized in that: In the mixture, the content of each component, by weight, is 85-90% high-density polyethylene and 10-15% silicone-containing flame-retardant polyurethane.

3. The method for preparing a high-strength, anti-breakage belt for a smoke machine according to claim 1, characterized in that: By weight, the amounts of each component are: 100 parts of mixed materials, 8-12 parts of compatibilizer, 5-9 parts of carbon nanotubes, 3-5 parts of light calcium carbonate, and 2-3 parts of antioxidant.

4. The method for preparing a high-strength, anti-breakage belt for a smoke machine according to claim 1, characterized in that: In step 1, toluene diisocyanate and polypropylene glycol 1000 react at a molar ratio of 2:

1.

5. The method for preparing a high-strength, anti-breakage belt for a smoke machine according to claim 1, characterized in that: In step 2, the weight ratio of benzoyl peroxide, acrylic acid and polyethylene is (0.5~0.8):(12~15):

100.

6. The method for preparing a high-strength, anti-breakage belt for a smoke machine according to claim 1, characterized in that: In step 3, the mass ratio of polyethylene grafted acrylic acid to polyurethane prepolymer is 100:(8~10).

7. The method for preparing a high-strength, anti-breakage belt for a smoke machine according to claim 1, characterized in that: In S1, toluene diisocyanate and polypropylene glycol 1000 react in a molar ratio of 2:1; in S2, the molar ratio of 3-amino-1,2,4-triazole, hydroxycitronellol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1; in S3, the components, by weight, are: 100 parts polyurethane prepolymer, 10-15 parts dihydroxy-terminated polydimethylsiloxane, 2-3 parts 1,4-butanediol, and 8-10 parts flame retardant.

8. The high-strength, anti-breakage belt for a smoke machine prepared by the preparation method according to any one of claims 1 to 7.

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