Flame-retardant neoprene and method for producing the same

Abstract

The present application relates to the field of rubber, in particular to a kind of flame-retardant neoprene and preparation method thereof.The present application first prepares the raw material of flame-retardant neoprene, mixes and masticates the raw material under certain conditions to obtain mixed rubber, and finally vulcanizes the mixed rubber to prepare a kind of flame-retardant neoprene;Its characteristics lie in that the composition of flame-retardant agent in the raw material of flame-retardant neoprene is the mixture of nano zinc oxide and nano magnesium oxide modified by silane coupling agent grafted onto hyperbranched polyester structure, which can improve the dispersibility of nano structure on one hand, prevent the occurrence of agglomeration phenomenon, and at the same time, the reaction efficiency can be improved by grafting the reactants together;On the other hand, the phosphorus-containing group and nitrogen-containing group of urea and phosphoric acid are grafted onto the hyperbranched polyester structure, so that the groups of hyperbranched polyester are rich in flame-retardant elements nitrogen and phosphorus, thereby significantly improving the flame-retardant performance of neoprene.

Description

Technical Field

[0001] This invention relates to the field of rubber, specifically to a flame-retardant chloroprene rubber and its preparation method. Background Technology

[0002] Chloroprene rubber is a commonly used synthetic rubber in chemical materials. It possesses numerous advantages, such as wear resistance, chemical corrosion resistance, oil resistance, and excellent resilience. Therefore, chloroprene rubber is widely used in conveyor belts, adhesives, wire and cable sheathing, hoses and belts, gaskets, and other fields. However, most flame-retardant chloroprene rubbers currently used in China employ halogenated flame retardants. While these flame retardants offer advantages such as low dosage, high flame-retardant efficiency, and minimal impact on the original properties of the material, they produce large amounts of harmful and corrosive gases during combustion, easily causing secondary injuries or fatalities in fires. Therefore, halogen-free flame retardants are gradually becoming the main direction of flame retardant research and development.

[0003] To overcome the shortcomings of the prior art, the present invention provides a flame-retardant chloroprene rubber and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a flame-retardant chloroprene rubber and its preparation method to solve the problems in the prior art.

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

[0006] A method for preparing flame-retardant chloroprene rubber includes the following steps:

[0007] Step 1: Mix chloroprene rubber and nitrile rubber, and then plasticize the mixture to prepare a compound.

[0008] Step 2: Add vulcanizing agent, accelerator, antioxidant, and flame retardant to the mixed rubber obtained in Step 1, mix and plasticize to prepare a mixed rubber compound;

[0009] Step 3: The mixed rubber compound prepared in Step 2 is fed into a vulcanizing machine for vulcanization to obtain the finished product.

[0010] In a more optimized manner, the mixing and plasticizing reaction conditions in step one are: temperature 70℃-80℃, pressure 1.0-3.0MPa, mixing for 20-40 minutes.

[0011] In a more optimized manner, the amounts of each component in the mixed rubber compound are as follows (by weight): 50-70 parts chloroprene rubber, 30-40 parts nitrile rubber, 0.05-0.15 parts vulcanizing agent, 0.5-1.5 parts accelerator, 0.3-0.5 parts antioxidant, and 20-30 parts flame retardant.

[0012] In a more optimized manner, the preparation method of the flame retardant in step two is as follows:

[0013] S1: Mix 3-5 parts of nano zinc oxide and 3-5 parts of nano magnesium oxide evenly by weight, add 30-50 parts of toluene to the mixture, and ultrasonically stir for 100-120 min; then slowly add 0.25-0.40 parts of silane coupling agent KH-550, slowly heat the reactants to 100-150℃, and reflux at a constant temperature for 1-3 h; filter the product under reduced pressure and wash with anhydrous ethanol, and dry it under vacuum at 50-70℃ to obtain modified nano zinc oxide-magnesium oxide;

[0014] S2: By weight, take 0.3-0.6 parts of modified nano zinc oxide-magnesium oxide and 25-40 parts of xylene, mix and stir for 40-60 min, then add 0.010-0.015 parts of p-toluenesulfonic acid catalyst, and slowly heat the reactants to 120-140℃ under nitrogen protection. After reaching a constant reflux temperature, add 1-1.5 parts of 2,2-dimethylolpropionic acid and react for 150-170 min. Filter the product under reduced pressure and dry it under vacuum at 50-70℃ to obtain polyester modified filler.

[0015] S3: By weight, mix 2-3 parts of polyester modified filler and 4-6 parts of phosphoric acid, stir continuously at 130-150℃ for 2-4 hours, add 3-4.5 parts of urea, and react at 100-120℃ for 1-3 hours; purify the product by precipitation with anhydrous ethanol, and dry at 80-100℃ for 10-15 minutes to prepare the flame retardant.

[0016] In a more optimized manner, in step two, the nano-zinc oxide particles have a size of 325 mesh, and the nano-magnesium oxide particles have a size of 300 mesh.

[0017] In a more optimized manner, in step two, the accelerator is 2,2'-dithiodibenzothiazole, the antioxidant is N,N-di-n-butyldithiocarbamate nickel, and the vulcanizing agent is 4,4'-dimorpholine disulfide.

[0018] In a more optimized manner, the mixing and plasticizing reaction conditions in step two are: temperature 60℃-80℃, pressure 1.0-2.0MPa, and mixing for 15-25 minutes.

[0019] In a more optimized manner, the vulcanization conditions in step three are: temperature 160℃-170℃, pressure 4.0-5.0MPa, and vulcanization for 15-25 minutes.

[0020] The beneficial effects of this invention are:

[0021] Chloroprene rubber is a commonly used synthetic rubber in chemical materials. It possesses numerous advantages, such as wear resistance, chemical corrosion resistance, oil resistance, and excellent resilience. This invention prepares a flame-retardant chloroprene rubber by adjusting the raw materials used in its preparation. Existing processes for preparing flame-retardant chloroprene rubber mostly utilize halogenated elements to enhance its flame-retardant properties. However, halogenated elements produce large amounts of harmful and corrosive gases during combustion, easily causing secondary injuries or fatalities. Therefore, halogen-free flame retardants have a promising future. The flame retardant component in the flame-retardant chloroprene rubber raw material of this invention consists of grafting a mixture of nano-zinc oxide and nano-magnesium oxide modified with a silane coupling agent onto a hyperbranched polyester structure. Furthermore, phosphorus-containing groups of urea and phosphoric acid are added to this hyperbranched structure, resulting in a flame retardant that is halogen-free, safe, and environmentally friendly, while being rich in the flame-retardant elements nitrogen and phosphorus, significantly improving the flame-retardant properties of chloroprene rubber.

[0022] This flame retardant improves the dispersibility of nano-zinc oxide and nano-magnesium oxide by grafting a mixture of nano-zinc oxide and nano-magnesium oxide modified with a silane coupling agent onto a hyperbranched polyester structure, preventing their agglomeration and thus protecting material properties. Furthermore, compared to grafting nano-zinc oxide and nano-magnesium oxide, commonly used reactants in the preparation of chloroprene rubber, onto the hyperbranched polyester structure results in more complete reactions between the reactants, leading to increased reaction efficiency.

[0023] By grafting phosphorus-containing and nitrogen-containing groups of urea and phosphoric acid onto a hyperbranched polyester structure, the content of flame-retardant elements nitrogen and phosphorus can be significantly increased due to the highly branched three-dimensional structure of the hyperbranched polyester, thus significantly improving the flame-retardant properties of chloroprene rubber. In addition, this structure can also combine the advantages of nitrogen-based and phosphorus-based flame retardants, synergistically exerting flame-retardant effects. Its flame-retardant effect is far greater than the flame-retardant effect of each component acting alone, thereby significantly improving the flame-retardant properties of chloroprene rubber. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Raw material sources: Nano zinc oxide, purchased from Hebei Bangtai Chemical Co., Ltd., model: ZA-100; Nano magnesium oxide, purchased from Hebei Yuechao Wear-resistant Materials Co., Ltd., model: 01; Accelerator 2,2'-dithiodibenzothiazole, purchased from Hebei Bangtai Chemical Co., Ltd., model: DM; Antioxidant N,N-di-n-butyldithiocarbamate nickel, purchased from Guangzhou Shanghe Chemical Technology Co., Ltd., model: NBC; Vulcanizing agent 4,4'-dimorpholine disulfide, purchased from Jiangsu Pules Biotechnology Co., Ltd., model: 103-34-4.

[0026] Example 1: Step 1: By weight, 70 parts of chloroprene rubber and 40 parts of nitrile rubber were mixed and plasticized at 80°C and 3.0 MPa for 40 min to prepare a mixed rubber.

[0027] Step Two: Preparation of Flame Retardant

[0028] S1: By mass, 5 parts of nano zinc oxide and 5 parts of nano magnesium oxide were mixed evenly, 50 parts of toluene were added to the mixture, and ultrasonic stirring was carried out for 120 min; then 0.40 parts of silane coupling agent KH-550 were slowly added, and the reactants were slowly heated to 150℃ and refluxed at a constant temperature for 3 h; the product was filtered under reduced pressure and washed with anhydrous ethanol, and dried under vacuum at 70℃ to obtain modified nano zinc oxide-magnesium oxide;

[0029] S2: By mass, 0.6 parts of modified nano zinc oxide-magnesium oxide and 40 parts of xylene were mixed and stirred for 60 min. Then, 0.015 parts of p-toluenesulfonic acid catalyst were added. Under nitrogen protection, the reactants were slowly heated to 140℃. After reaching a constant reflux temperature, 1.5 parts of 2,2-dimethylolpropionic acid were added and reacted for 170 min. The product was filtered under reduced pressure and dried under vacuum at 70℃ to obtain polyester modified filler.

[0030] S3: By mass, 3 parts of polyester modified filler and 6 parts of phosphoric acid were mixed and stirred continuously at 150°C for 4 hours. Then, 4.5 parts of urea were added and reacted at 120°C for 3 hours. The product was purified by precipitation with anhydrous ethanol and dried at 100°C for 15 minutes to prepare the flame retardant.

[0031] Step 3: By weight, add 0.15 parts of 4,4'-dimorpholine disulfide, 1.5 parts of 2,2'-dithiodibenzothiazole, 0.5 parts of N,N-di-n-butyldithiocarbamate, and 30 parts of flame retardant to the mixed rubber; mix and plasticize at 80°C and 2.0 MPa for 25 min to prepare the mixed rubber compound;

[0032] Step 4: The mixed rubber compound prepared in Step 3 is fed into a vulcanizing machine and vulcanized at 170℃ and 5.0MPa for 25 minutes to obtain the finished product.

[0033] Example 2: Step 1: By weight, 70 parts of chloroprene rubber and 40 parts of nitrile rubber were mixed and plasticized at a temperature of 75°C and a pressure of 2.0 MPa for 30 minutes to prepare a mixed rubber.

[0034] Step Two: Preparation of Flame Retardant

[0035] S1: By mass, 5 parts of nano zinc oxide and 5 parts of nano magnesium oxide were mixed evenly, 50 parts of toluene were added to the mixture, and ultrasonic stirring was carried out for 110 min; then 0.40 parts of silane coupling agent KH-550 were slowly added, and the reactants were slowly heated to 125℃ and refluxed at a constant temperature for 2 h; the product was filtered under reduced pressure and washed with anhydrous ethanol, and dried under vacuum at 60℃ to obtain modified nano zinc oxide-magnesium oxide;

[0036] S2: By mass, 0.6 parts of modified nano zinc oxide-magnesium oxide and 40 parts of xylene were mixed and stirred for 50 min. Then, 0.015 parts of p-toluenesulfonic acid catalyst were added. Under nitrogen protection, the reactants were slowly heated to 130℃. After reaching a constant reflux temperature, 1.5 parts of 2,2-dimethylolpropionic acid were added and reacted for 160 min. The product was filtered under reduced pressure and dried under vacuum at 60℃ to obtain polyester modified filler.

[0037] S3: By mass, 3 parts of polyester modified filler and 6 parts of phosphoric acid were mixed and stirred at 140°C for 3 hours. Then, 4.5 parts of urea were added and reacted at 110°C for 2 hours. The product was purified by precipitation with anhydrous ethanol and dried at 90°C for 12 minutes to prepare the flame retardant.

[0038] Step 3: By weight, add 0.15 parts of 4,4'-dimorpholine disulfide, 1.5 parts of 2,2'-dithiodibenzothiazole, 0.5 parts of N,N-di-n-butyldithiocarbamate, and 30 parts of flame retardant to the mixed rubber to prepare the mixed rubber compound;

[0039] Step 4: The mixed rubber compound prepared in Step 3 is fed into a vulcanizing machine and vulcanized at a temperature of 165℃ and a pressure of 4.5MPa for 20 minutes to obtain the finished product.

[0040] Example 3: Step 1: By weight, 70 parts of chloroprene rubber and 40 parts of nitrile rubber were mixed and plasticized at 70°C and 1.0 MPa for 20 minutes to prepare a mixed rubber.

[0041] Step Two: Preparation of Flame Retardant

[0042] S1: By mass, 5 parts of nano zinc oxide and 5 parts of nano magnesium oxide were mixed evenly, 50 parts of toluene were added to the mixture, and ultrasonic stirring was carried out for 100 min; then 0.40 parts of silane coupling agent KH-550 were slowly added, and the reactants were slowly heated to 100℃ and refluxed at a constant temperature for 1 h; the product was filtered under reduced pressure and washed with anhydrous ethanol, and dried under vacuum at 50℃ to obtain modified nano zinc oxide-magnesium oxide;

[0043] S2: By mass, 0.6 parts of modified nano zinc oxide-magnesium oxide and 40 parts of xylene were mixed and stirred for 40 min. Then, 0.015 parts of p-toluenesulfonic acid catalyst were added. Under nitrogen protection, the reactants were slowly heated to 120℃. After reaching a constant reflux temperature, 1.5 parts of 2,2-dimethylolpropionic acid were added and reacted for 150 min. The product was filtered under reduced pressure and dried under vacuum at 50℃ to obtain polyester modified filler.

[0044] S3: By weight, 3 parts of polyester modified filler and 6 parts of phosphoric acid were mixed and stirred at 130°C for 2 hours. Then, 4.5 parts of urea were added and reacted at 100°C for 1 hour. The product was purified by precipitation with anhydrous ethanol and dried at 80°C for 10 minutes to prepare the flame retardant.

[0045] Step 3: By weight, add 0.15 parts of 4,4'-dimorpholine disulfide, 1.5 parts of 2,2'-dithiodibenzothiazole, 0.5 parts of N,N-di-n-butyldithiocarbamate, and 30 parts of flame retardant to the mixed rubber; mix and plasticize at 60°C and 1.0 MPa for 15 min to prepare the mixed rubber compound;

[0046] Step 4: The mixed rubber compound prepared in Step 3 is fed into a vulcanizing machine and vulcanized at 160℃ and 4.0MPa for 15 minutes to obtain the finished product.

[0047] Comparative Example 1: The amount of nitrogen source and phosphorus source used in step two: the preparation of flame retardant is halved, and the rest is the same as in Example 1. The specific steps are as follows: Step one: 70 parts by mass of chloroprene rubber and 40 parts by mass of nitrile rubber are mixed and plasticized at a temperature of 80°C and a pressure of 3.0 MPa for 40 min to prepare a mixed rubber.

[0048] Step Two: Preparation of Flame Retardant

[0049] S1: By mass, 5 parts of nano zinc oxide and 5 parts of nano magnesium oxide were mixed evenly, 50 parts of toluene were added to the mixture, and ultrasonic stirring was carried out for 120 min; then 0.40 parts of silane coupling agent KH-550 were slowly added, and the reactants were slowly heated to 150℃ and refluxed at a constant temperature for 3 h; the product was filtered under reduced pressure and washed with anhydrous ethanol, and dried under vacuum at 70℃ to obtain modified nano zinc oxide-magnesium oxide;

[0050] S2: By mass, 0.6 parts of modified nano zinc oxide-magnesium oxide and 40 parts of xylene were mixed and stirred for 60 min. Then, 0.015 parts of p-toluenesulfonic acid catalyst were added. Under nitrogen protection, the reactants were slowly heated to 140℃. After reaching a constant reflux temperature, 1.5 parts of 2,2-dimethylolpropionic acid were added and reacted for 170 min. The product was filtered under reduced pressure and dried under vacuum at 70℃ to obtain polyester modified filler.

[0051] S3: By mass, 3 parts of polyester modified filler and 3 parts of phosphoric acid were mixed and stirred continuously at 150°C for 4 hours. Then, 2.25 parts of urea were added and reacted at 120°C for 3 hours. The product was purified by precipitation with anhydrous ethanol and dried at 100°C for 15 minutes to prepare the flame retardant.

[0052] Step 3: By weight, add 0.15 parts of 4,4'-dimorpholine disulfide, 1.5 parts of 2,2'-dithiodibenzothiazole, 0.5 parts of N,N-di-n-butyldithiocarbamate, and 30 parts of flame retardant to the mixed rubber; mix and plasticize at 80°C and 2.0 MPa for 25 min to prepare the mixed rubber compound;

[0053] Step 4: The mixed rubber compound prepared in Step 3 is fed into a vulcanizing machine and vulcanized at 170℃ and 5.0MPa for 25 minutes to obtain the finished product.

[0054] Comparative Example 2: Step 2: Preparation of flame retardant is removed, and the rest is the same as in Example 1. The specific steps are as follows: Step 1: 70 parts by weight of chloroprene rubber and 40 parts by weight of nitrile rubber are mixed and plasticized at a temperature of 80°C and a pressure of 3.0 MPa for 40 min to prepare a mixed rubber.

[0055] Step 2: By weight, add 0.15 parts of 4,4'-dimorpholine disulfide, 1.5 parts of 2,2'-dithiodibenzothiazole, and 0.5 parts of N,N-di-n-butyldithiocarbamate to the mixed rubber; mix and plasticize at 80°C and 2.0 MPa for 25 min to prepare the mixed rubber compound;

[0056] Step 3: The mixed rubber compound prepared in Step 2 is fed into a vulcanizing machine and vulcanized at 170℃ and 5.0MPa for 25 minutes to obtain the finished product.

[0057] Comparative Example 3: The amount of 2,2-dimethylolpropionic acid in step two: the preparation of flame retardant was halved, that is, the amount of hyperbranched polyester was halved. The rest was the same as in Example 1. The specific steps are as follows: Step one: 70 parts by weight of chloroprene rubber and 40 parts by weight of nitrile rubber were mixed and plasticized at a temperature of 80°C and a pressure of 3.0 MPa for 40 min to prepare a mixed rubber.

[0058] Step Two: Preparation of Flame Retardant

[0059] S1: By mass, 5 parts of nano zinc oxide and 5 parts of nano magnesium oxide were mixed evenly, 50 parts of toluene were added to the mixture, and ultrasonic stirring was carried out for 120 min; then 0.40 parts of silane coupling agent KH-550 were slowly added, and the reactants were slowly heated to 150℃ and refluxed at a constant temperature for 3 h; the product was filtered under reduced pressure and washed with anhydrous ethanol, and dried under vacuum at 70℃ to obtain modified nano zinc oxide-magnesium oxide;

[0060] S2: By mass, 0.6 parts of modified nano zinc oxide-magnesium oxide and 40 parts of xylene were mixed and stirred for 60 min. Then, 0.015 parts of p-toluenesulfonic acid catalyst were added. Under nitrogen protection, the reactants were slowly heated to 140℃. After reaching a constant reflux temperature, 0.75 parts of 2,2-dimethylolpropionic acid were added and reacted for 170 min. The product was filtered under reduced pressure and dried under vacuum at 70℃ to obtain polyester modified filler.

[0061] S3: By mass, 3 parts of polyester modified filler and 6 parts of phosphoric acid were mixed and stirred continuously at 150°C for 4 hours. Then, 4.5 parts of urea were added and reacted at 120°C for 3 hours. The product was purified by precipitation with anhydrous ethanol and dried at 100°C for 15 minutes to prepare the flame retardant.

[0062] Step 3: By weight, add 0.15 parts of 4,4'-dimorpholine disulfide, 1.5 parts of 2,2'-dithiodibenzothiazole, 0.5 parts of N,N-di-n-butyldithiocarbamate, and 30 parts of flame retardant to the mixed rubber; mix and plasticize at 80°C and 2.0 MPa for 25 min to prepare the mixed rubber compound;

[0063] Step 4: The mixed rubber compound prepared in Step 3 is fed into a vulcanizing machine and vulcanized at 170℃ and 5.0MPa for 25 minutes to obtain the finished product.

[0064] Comparative Example 4: The addition of hyperbranched polyester in step two: the preparation of flame retardant was removed, and the rest was the same as in Example 1. The specific steps are as follows: Step one: 70 parts by weight of chloroprene rubber and 40 parts by weight of nitrile rubber were mixed and plasticized at a temperature of 80°C and a pressure of 3.0 MPa for 40 min to prepare a mixed rubber.

[0065] Step 2: Mix 5 parts by weight of nano zinc oxide, 5 parts by weight of nano magnesium oxide, 6 parts by weight of phosphoric acid, and 4.5 parts by weight of urea to prepare a flame retardant.

[0066] Step 3: By weight, add 0.15 parts of 4,4'-dimorpholine disulfide, 1.5 parts of 2,2'-dithiodibenzothiazole, 0.5 parts of N,N-di-n-butyldithiocarbamate, and 30 parts of flame retardant to the mixed rubber; mix and plasticize at 80°C and 2.0 MPa for 25 min to prepare the mixed rubber compound;

[0067] Step 4: The mixed rubber compound prepared in Step 3 is fed into a vulcanizing machine and vulcanized at 170℃ and 5.0MPa for 25 minutes to obtain the finished product.

[0068] Testing and experimentation:

[0069] Oxygen index performance test: determined according to GB / T2406.2-2009 standard. Sample size: length 70mm, width 7.0mm, thickness 3mm. The initial oxygen concentration was selected as 21%. A mixture of oxygen and nitrogen was introduced into the environment at 25℃ at a flow rate of 40mm / s. The oxygen index was then calculated using the formula. The higher the oxygen index, the better the flame retardant performance.

[0070] Tensile property test: The tensile properties of the specimens were tested using an electronic tensile testing machine according to GB / T528-2009. Dumbbell-shaped specimens were used, and the tensile rate was 500 mm / min. The tensile strength was obtained as follows:

[0071]

[0072]

[0073] Conclusion: In Examples 1-3, the dosage remained unchanged, with only some reaction parameters modified. Experimental data showed no significant fluctuations in the properties of chloroprene rubber. Comparative Example 1: In step two, the dosage of nitrogen and phosphorus sources in the preparation of the flame retardant was halved, while the rest remained the same as in Example 1. Experimental data showed a decrease in the oxygen index and an increase in tensile strength. The reason for this is that urea and phosphoric acid are the sources of the flame-retardant elements nitrogen and phosphorus in the flame retardant. Therefore, halving the dosage of nitrogen and phosphorus sources resulted in a decrease in flame-retardant performance, a decrease in the oxygen index to 33%, and an increase in tensile strength to 15 MPa.

[0074] Comparative Example 2: Step 2, the preparation of the flame retardant, was removed, and the rest was the same as in Example 1. The experimental data showed that the oxygen index decreased significantly and the tensile strength increased. The reason for this is that removing the flame retardant directly would significantly reduce the flame retardant properties of chloroprene rubber, with the oxygen index decreasing to 25%. The tensile strength increased to 18 MPa. The reason for this is that the reduction in the amount of flame retardant increases the uniformity of the structure, making it less likely for stress concentration points to occur during the stretching process, thus increasing the tensile strength of the material.

[0075] Comparative Example 3: The amount of 2,2-dimethylolpropionic acid in step two, the preparation of the flame retardant, was halved, i.e., the amount of hyperbranched polyester was halved. The rest was the same as in Example 1. The experimental data showed that the oxygen index decreased and the tensile strength increased. The reason for this is that in Comparative Example 3, the amount of reactants used to prepare the hyperbranched polyester was halved. Therefore, the number of grafting sites in the mixture of nano zinc oxide and nano magnesium oxide modified by silane coupling agent decreased, and the number of elements in the flame retardant that could play a flame retardant role decreased, resulting in a worse flame retardant performance of the flame retardant component. The oxygen index decreased to 35%, and the tensile strength increased to 15 MPa.

[0076] Comparative Example 4: The addition of hyperbranched polyester in step two, the preparation of the flame retardant, was removed. The rest was the same as in Example 1. The experimental data showed that the oxygen index decreased and the tensile strength increased. The reason for this was that the process of preparing hyperbranched polyester was removed in Comparative Example 4. The flame retardant only consisted of a mixture of nano zinc oxide and nano magnesium oxide modified by silane coupling agent. Although the amounts of urea and phosphoric acid, as the sources of flame retardant elements nitrogen and phosphorus in the flame retardant, were not changed, the removal of the hyperbranched polymer hyperbranched polyester prevented the flame retardant elements nitrogen and phosphorus from fully reacting by grafting onto the hyperbranched polyester. This resulted in a decrease in reaction efficiency, a deterioration in flame retardant performance, a decrease in the oxygen index to 32%, and an increase in tensile strength to 18 MPa.

[0077] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process method article or apparatus.

[0078] 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 flame-retardant chloroprene rubber, characterized in that, Includes the following steps: Step 1: Mix chloroprene rubber and nitrile rubber, and then plasticize the mixture to prepare a compound. Step 2: Add vulcanizing agent, accelerator, antioxidant, and flame retardant to the mixed rubber obtained in Step 1, mix and plasticize to prepare a mixed rubber compound; the amount of each component in the mixed rubber compound is as follows (by weight): 50-70 parts chloroprene rubber, 30-40 parts nitrile rubber, 0.05-0.15 parts vulcanizing agent, 0.5-1.5 parts accelerator, 0.3-0.5 parts antioxidant, and 20-30 parts flame retardant; The preparation method of flame retardant is as follows: S1: Mix nano zinc oxide and nano magnesium oxide evenly, add toluene to the mixture, and ultrasonically stir for 100-120 min; then slowly add silane coupling agent KH-550, slowly heat the reactants to 100-150℃, and reflux at a constant temperature for 1-3 h. The product was filtered under reduced pressure and washed with anhydrous ethanol, and then dried under vacuum at 50-70℃ to obtain modified nano zinc oxide-magnesium oxide. S2: Mix modified nano zinc oxide-magnesium oxide and xylene and stir for 40-60 min, then add the catalyst p-toluenesulfonic acid. Under nitrogen protection, slowly heat the reactants to 120-140℃. After reaching a constant reflux temperature, add 2,2-dimethylolpropionic acid and react for 150-170 min. Filter the product under reduced pressure and dry it under vacuum at 50-70℃ to obtain polyester modified filler. S3: Mix polyester modified filler and phosphoric acid, stir continuously at 130-150℃ for 2-4 hours, add urea, and react at 100-120℃ for 1-3 hours; purify the product by precipitation with anhydrous ethanol, and dry at 80-100℃ for 10-15 minutes to prepare the flame retardant. Step 3: The mixed rubber compound prepared in Step 2 is fed into a vulcanizing machine for vulcanization to obtain the finished product.

2. The method for preparing flame-retardant chloroprene rubber according to claim 1, characterized in that, In step one, the mixing and plasticizing reaction conditions are: temperature 70℃-80℃, pressure 1.0-3.0MPa, mixing for 20-40 minutes.

3. The method for preparing flame-retardant chloroprene rubber according to claim 1, characterized in that, In step two, the accelerator is 2,2'-dithiodibenzothiazole, the antioxidant is N,N-di-n-butyldithiocarbamate nickel, and the vulcanizing agent is 4,4'-dimorpholine disulfide.

4. The method for preparing flame-retardant chloroprene rubber according to claim 1, characterized in that, In step two, the mixing and plasticizing reaction conditions are: temperature 60℃-80℃, pressure 1.0-2.0MPa, mixing for 15-25 minutes.

5. The method for preparing flame-retardant chloroprene rubber according to claim 1, characterized in that, In step three, the vulcanization conditions are: temperature 160℃-170℃, pressure 4.0-5.0MPa, vulcanization for 15-25 minutes.

6. A flame-retardant neoprene rubber, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

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