Composition for preparing halogen-free flame-retardant thermoplastic elastomer, halogen-free flame-retardant thermoplastic elastomer as well as preparation method and application of halogen-free flame-retardant thermoplastic elastomer

Abstract

The invention relates to the field of butyl rubber, and discloses a composition for preparing a halogen-free flame-retardant thermoplastic elastomer, the halogen-free flame-retardant thermoplastic elastomer as well as a preparation method and application of the halogen-free flame-retardant thermoplastic elastomer. The composition contains nitrile rubber, polypropylene, a vulcanizing agent, a flame retardant, a compatibilizer and an inorganic filler, wherein based on 100 parts by weight of the nitrile rubber, the content of the polypropylene is 20-80 parts by weight, the content of the vulcanizing agent is 0.05-2 parts by weight, the content of the flame retardant is 10-50 parts by weight, the content of the compatibilizer is 5-30 parts by weight, the content of the inorganic filler is 5-20 parts by weight, and the content of the flame retardant is 0.5-2 parts by weight. The flame retardant contains diammonium hydrogen phosphate, zinc borate, dicyandiamide and alumina trihydrate. The halogen-free flame-retardant thermoplastic elastomer prepared by using the composition of the halogen-free flame-retardant thermoplastic elastomer has high flame retardant property, mechanical property and oil resistance.

Description

Technical Field

[0001] This invention relates to the field of butyl rubber, and more specifically, to a composition for preparing halogen-free flame-retardant thermoplastic elastomers, the halogen-free flame-retardant thermoplastic elastomers, their preparation methods, and applications. Background Technology

[0002] Dynamically vulcanized thermoplastic elastomers (TPVs) are rubber-plastic composite thermoplastic elastomers produced using dynamic vulcanization technology. Dynamic vulcanization refers to the process where, under high temperature and high shear conditions, the rubber, under the action of a crosslinking agent, undergoes vulcanization while simultaneously breaking down and dispersing into the continuous phase of the plastic, ultimately forming a micron-sized vulcanized rubber phase within the continuous plastic phase. TPVs successfully combine some of the properties of vulcanized rubber, such as heat resistance and low compression set, with the easy processing characteristics of thermoplastics. Furthermore, they are environmentally friendly, recyclable, and have a wide range of applications.

[0003] Nitrile butadiene rubber (NBR) is a high-performance, oil-resistant rubber, while polypropylene (PP) is a crystalline thermoplastic resin with low specific gravity, high strength, good heat resistance, good electrical insulation, and excellent water and chemical resistance. However, their molecular structures and polarities differ, making them incompatible polymer systems. Direct blending yields materials with limited practical value. Therefore, NBR / PP blends must be compatibilized to produce products with practical applications. Compatibilized NBR / PP thermoplastic elastomers possess good tensile strength, abrasion resistance, and excellent oil resistance, as well as high elasticity, ease of processing, and reprocessing properties, making them suitable for automotive fuel lines and sealing components. However, both nitrile butadiene rubber and polypropylene are flammable in air, producing large amounts of dense smoke and toxic gases during combustion. Therefore, the automotive industry imposes stringent flame-retardant requirements on the plastics and rubber materials used.

[0004] To meet the flame-retardant and environmentally friendly requirements of nitrile rubber / polypropylene thermoplastic elastomers in automotive fuel lines and seals, it is necessary to develop a halogen-free flame-retardant nitrile rubber / polypropylene thermoplastic elastomer material. Summary of the Invention

[0005] The purpose of this invention is to provide a composition for preparing halogen-free flame-retardant thermoplastic elastomers, halogen-free flame-retardant thermoplastic elastomers, their preparation methods and applications. The halogen-free flame-retardant thermoplastic elastomers prepared using the composition of this invention possess high flame-retardant properties, mechanical properties and oil resistance.

[0006] Through in-depth research, the inventors of this invention discovered that by using the specific composition of this invention for preparing halogen-free flame-retardant thermoplastic elastomers, and by mixing and dynamic vulcanization, the resulting halogen-free flame-retardant thermoplastic elastomers can possess high flame-retardant properties, mechanical properties, and oil resistance, thus completing this invention.

[0007] Therefore, a first aspect of the present invention provides a composition for preparing a halogen-free flame-retardant thermoplastic elastomer, wherein the composition contains nitrile rubber, polypropylene, a vulcanizing agent, a flame retardant, a compatibilizer, and an inorganic filler; wherein, relative to 100 parts by weight of the nitrile rubber, the content of the polypropylene is 20-80 parts by weight, the content of the vulcanizing agent is 0.05-2 parts by weight, the content of the flame retardant is 10-50 parts by weight, the content of the compatibilizer is 5-30 parts by weight, the content of the inorganic filler is 5-20 parts by weight, and the flame retardant contains diammonium hydrogen phosphate, zinc borate, dicyandiamide, and alumina trihydrate.

[0008] Preferably, relative to 100 parts by weight of the nitrile rubber, the content of the polypropylene is 30-60 parts by weight, the content of the vulcanizing agent is 0.1-1 parts by weight, the content of the flame retardant is 30-40 parts by weight, the content of the compatibilizer is 10-20 parts by weight, and the content of the inorganic filler is 10-15 parts by weight.

[0009] Preferably, the acrylonitrile structural unit content in the nitrile rubber is 15-45% by weight, more preferably 20-40% by weight.

[0010] Preferably, the polypropylene is homopolymer polypropylene and / or copolymer polypropylene.

[0011] Preferably, the vulcanizing agent is one or more selected from dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,4-bis(tert-butylperoxydiisopropyl)benzene, 1,3-bis(tert-butylperoxydiisopropyl)benzene, 2,5-dimethyl-2,5-(di-tert-butylperoxy)-3-hexyne, ethyl-3,3-di(tert-butylperoxy)butyrate, ethyl-3,3-di(tert-pentylperoxy)butyrate, benzoyl peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, 1,1-di(tert-pentylperoxy)cyclohexane, and tert-butylperoxybenzoate.

[0012] Preferably, the weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide and alumina trihydrate is 4:(0.8-1.2):(0.8-1.2):(0.08-0.12).

[0013] Preferably, the compatibilizer is selected from one or more of dioctyl phthalate, polyol benzoate, trioctyl trimellitate, and dioctyl sebacate.

[0014] Preferably, the inorganic filler is selected from one or more of kaolin, talc, calcium carbonate, silica, and carbon black.

[0015] Preferably, the composition further contains an antioxidant, and the antioxidant content is 1-7 parts by weight, preferably 1.5-5 parts by weight, relative to 100 parts by weight of the nitrile rubber.

[0016] Preferably, the antioxidant is selected from one or more of amine antioxidants, quinoline antioxidants, and benzimidazole antioxidants.

[0017] According to a second aspect of the present invention, a halogen-free flame-retardant thermoplastic elastomer is provided, which is prepared by using the composition for preparing a halogen-free flame-retardant thermoplastic elastomer described in the first aspect of the present invention.

[0018] According to a third aspect of the present invention, a method for preparing a halogen-free flame-retardant thermoplastic elastomer is provided, which is prepared by using the composition for preparing a halogen-free flame-retardant thermoplastic elastomer described in the first aspect of the present invention as a raw material.

[0019] Preferably, the method includes:

[0020] 1) The step of mixing the nitrile rubber, the compatibilizer, the inorganic filler and the optional antioxidant to obtain the masterbatch;

[0021] 2) The step of extruding and granulating the masterbatch to obtain masterbatch granules;

[0022] 3) The step of dynamically vulcanizing the masterbatch granules, the polypropylene, the vulcanizing agent and the flame retardant.

[0023] Preferably, in step 1), the mixing temperature is 100-130°C.

[0024] Preferably, in step 1), the mixing is carried out in an internal mixer.

[0025] Preferably, in step 2), the extrusion granulation is carried out in a single-screw extruder.

[0026] Preferably, in step 3), the dynamic vulcanization is carried out in a co-rotating twin-screw extruder.

[0027] Preferably, in step 3), the conditions for dynamic vulcanization include: screw speed of 100-600 rpm and temperature of 160-230℃.

[0028] According to a fourth aspect of the present invention, a halogen-free flame-retardant thermoplastic elastomer is provided, which is prepared by the method described in the third aspect of the present invention.

[0029] According to a fifth aspect of the present invention, the application of the thermoplastic elastomer described in the second and fourth aspects of the present invention in the manufacture of oil pipelines and sealing components is provided.

[0030] Through the above technical solutions, the present invention can provide a composition for preparing halogen-free flame-retardant thermoplastic elastomers, halogen-free flame-retardant thermoplastic elastomers, their preparation methods and applications. The halogen-free flame-retardant thermoplastic elastomers prepared using the composition of the present invention have high flame-retardant properties, mechanical properties and oil resistance, and also have high elasticity, easy processing and reprocessing properties, making them particularly suitable for the preparation of oil pipelines and sealing components. Detailed Implementation

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] In a first aspect, the present invention provides a composition for preparing a halogen-free flame-retardant thermoplastic elastomer, wherein the composition comprises nitrile rubber, polypropylene, a vulcanizing agent, a flame retardant, a compatibilizer, and an inorganic filler; wherein, relative to 100 parts by weight of the nitrile rubber, the content of the polypropylene is 20-80 parts by weight, the content of the vulcanizing agent is 0.05-2 parts by weight, the content of the flame retardant is 10-50 parts by weight, the content of the compatibilizer is 5-30 parts by weight, and the content of the inorganic filler is 5-20 parts by weight, and the flame retardant comprises diammonium hydrogen phosphate, zinc borate, dicyandiamide, and alumina trihydrate.

[0033] To further improve the flame retardant, mechanical, and oil resistance properties, preferably, relative to 100 parts by weight of the nitrile rubber, the content of the polypropylene is 30-60 parts by weight, the content of the vulcanizing agent is 0.1-1 parts by weight, the content of the flame retardant is 30-40 parts by weight, the content of the compatibilizer is 10-20 parts by weight, and the content of the inorganic filler is 10-15 parts by weight.

[0034] Specific examples of the polypropylene content relative to 100 parts by weight of the nitrile rubber include, for example: 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight. The weights are 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, 66 parts, 67 parts, 68 parts, 69 parts, 70 parts, 71 parts, 72 parts, 73 parts, 74 parts, 75 parts, 76 parts, 77 parts, 78 parts, 79 parts, 80 parts, etc., as well as any range of any two of the above values.

[0035] Specific examples of the content of the vulcanizing agent relative to 100 parts by weight of the nitrile rubber include, for example, 0.05 parts by weight, 0.08 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, etc., as well as any range of any two of the above values.

[0036] Specific examples of the flame retardant content relative to 100 parts by weight of the nitrile rubber include, for example, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, etc., as well as any range given by any two of the above values.

[0037] Specific examples of the compatibilizer content relative to 100 parts by weight of the nitrile rubber include, for example, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, etc., as well as any range given by any two of the above values.

[0038] Specific examples of the content of the inorganic filler relative to 100 parts by weight of the nitrile rubber include, for example, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, etc., as well as any range given by any two of the above values.

[0039] According to the present invention, preferably, the content of acrylonitrile structural units in the nitrile rubber is 15-45% by weight; more preferably, the content of acrylonitrile structural units in the nitrile rubber is 20-40% by weight. For example, the content of acrylonitrile structural units in the nitrile rubber can be: 15% by weight, 16% by weight, 17% by weight, 18% by weight, 19% by weight, 20% by weight, 21% by weight, 22% by weight, 23% by weight, 24% by weight, 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, etc.

[0040] According to the present invention, preferably, the polypropylene is homopolymer polypropylene and / or copolymer polypropylene.

[0041] According to the present invention, preferably, the weight-average molecular weight of the polypropylene is 20,000-900,000 g / mol; more preferably, the weight-average molecular weight of the polypropylene is 300,000-400,000 g / mol.

[0042] According to the present invention, preferably, the melt flow rate of the polypropylene at 230°C and 2.16 kg load is 1-20 g / 10 min; more preferably, the melt flow rate of the polypropylene at 230°C and 2.16 kg load is 2-10 g / 10 min; and even more preferably, the melt flow rate of the polypropylene at 230°C and 2.16 kg load is 2-5 g / 10 min.

[0043] According to the present invention, preferably, the vulcanizing agent is dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,4-bis(tert-butylperoxydiisopropyl)benzene, 1,3-bis(tert-butylperoxydiisopropyl)benzene, 2,5-dimethyl-2,5-(di-tert-butylperoxy)-3-hexyne, ethyl-3,3-di(tert-butylperoxy)butyrate, ethyl-3,3-di(tert-pentylperoxy)butyrate, etc. The vulcanizing agent is one or more of dibenzoyl peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, 1,1-di(tert-pentylperoxy)cyclohexane, and tert-butylperoxybenzoate; more preferably, the vulcanizing agent is one or more of dicumyl peroxide, benzoyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; even more preferably, the vulcanizing agent is dicumyl peroxide.

[0044] According to the present invention, from the perspective of further improving flame retardant properties, mechanical properties and oil resistance, the weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide and alumina trihydrate is preferably 4:(0.8-1.2):(0.8-1.2):(0.08-0.12).

[0045] In one specific embodiment of the present invention, the weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide and alumina trihydrate is 4:1:1.2:0.12.

[0046] In another specific embodiment of the present invention, the weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide and alumina trihydrate is 4:0.8:0.8:0.08.

[0047] In another specific embodiment of the present invention, the weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide and alumina trihydrate is 4:1.2:1.2:0.12.

[0048] According to the present invention, the compatibilizer is used to make polypropylene and nitrile rubber compatible. Preferably, the compatibilizer is selected from one or more of dioctyl phthalate, polyol benzoate, trioctyl trimellitate and dioctyl sebacate; more preferably, the compatibilizer is dioctyl phthalate.

[0049] According to the present invention, preferably, the inorganic filler is selected from one or more of kaolin, talc, calcium carbonate, silica, and carbon black; more preferably, the inorganic filler is calcium carbonate; and even more preferably, the inorganic filler is nano-calcium carbonate.

[0050] In this invention, by using the composition specifically designed for preparing halogen-free flame-retardant thermoplastic elastomers, and by mixing and dynamic vulcanization, the resulting halogen-free flame-retardant thermoplastic elastomer can possess high flame retardant properties, mechanical properties, and oil resistance.

[0051] According to the present invention, in order to further improve the antioxidant properties, preferably, the composition further contains an antioxidant, wherein the content of the antioxidant is 1-7 parts by weight relative to 100 parts by weight of the nitrile rubber; preferably, the content of the antioxidant is 1.5-5 parts by weight relative to 100 parts by weight of the nitrile rubber.

[0052] Specific examples of the antioxidant content relative to 100 parts by weight of the nitrile rubber include, for example, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, etc., as well as any range given by any two of the above values.

[0053] There are no particular limitations on the antioxidant; any substance commonly used in the art for antioxidation can be used. Preferably, the antioxidant is selected from one or more of amine antioxidants, quinoline antioxidants, and benzimidazole antioxidants. For example, 2,2,4-trimethyl-1,2-dihydrovalerine can be used.

[0054] According to a second aspect of the present invention, a halogen-free flame-retardant thermoplastic elastomer is provided, which is prepared by using the composition for preparing a halogen-free flame-retardant thermoplastic elastomer described in the first aspect of the present invention.

[0055] According to a third aspect of the present invention, a method for preparing a halogen-free flame-retardant thermoplastic elastomer is provided, which is prepared by using the composition for preparing a halogen-free flame-retardant thermoplastic elastomer described in the first aspect of the present invention as a raw material.

[0056] Preferably, the method includes:

[0057] 1) The step of mixing the nitrile rubber, the compatibilizer, the inorganic filler and the optional antioxidant to obtain the masterbatch;

[0058] 2) The step of extruding and granulating the masterbatch to obtain masterbatch granules;

[0059] 3) The step of dynamically vulcanizing the masterbatch granules, the polypropylene, the vulcanizing agent and the flame retardant.

[0060] Preferably, in step 1), the mixing temperature is 100-130°C.

[0061] Preferably, in step 1), the mixing is carried out in an internal mixer.

[0062] Preferably, in step 2), the extrusion granulation is carried out in a single-screw extruder.

[0063] Preferably, in step 3), the dynamic vulcanization is carried out in a co-rotating twin-screw extruder.

[0064] Preferably, in step 3), the conditions for dynamic vulcanization include: screw speed of 100-600 rpm and temperature of 160-230℃.

[0065] According to a fourth aspect of the present invention, a halogen-free flame-retardant thermoplastic elastomer is provided, which is prepared by the method described in the third aspect of the present invention.

[0066] According to a fifth aspect of the present invention, the application of the thermoplastic elastomer described in the second and fourth aspects of the present invention in the manufacture of oil pipelines and sealing components is provided.

[0067] The halogen-free flame-retardant thermoplastic elastomer prepared using the composition of the present invention has high flame retardant properties, mechanical properties and oil resistance, as well as high elasticity, easy processing and reprocessing properties, making it particularly suitable for the preparation of oil pipelines and sealing components.

[0068] The present invention will be described in detail below through embodiments, but the present invention is not limited to the following embodiments.

[0069] Examples 1-10

[0070] This embodiment illustrates the halogen-free flame-retardant nitrile rubber / polypropylene thermoplastic elastomer and its preparation method of the present invention.

[0071] According to the formula shown in Table 1, the elastomers P1-P10 are obtained by processing them according to the following processing method.

[0072] (1) At a temperature of 120°C, nitrile rubber, compatibilizer, antioxidant and inorganic filler are added to a mixer in sequence and mixed for 10 minutes to obtain masterbatch. The masterbatch is then extruded and granulated through a single screw extruder to obtain masterbatch granules.

[0073] (2) Using a co-rotating twin-screw extruder, the processing temperature is 200℃ and the screw speed is 300rpm. The compound particles obtained in step (1), as well as polypropylene, vulcanizing agent and flame retardant are added. TPV particles are obtained by dynamic vulcanization extrusion and granulation.

[0074] The nitrile rubber was purchased from JSR Corporation of Japan under the grade N220S, and the acrylonitrile content was 41% by weight.

[0075] Polypropylene: purchased from Sinopec Yangzi Petrochemical Co., Ltd., grade F401, with a weight-average molecular weight of 380,000-400,000 g / mol and a melt flow rate of 2.5 g / 10 min at 230℃ and 2.16 kg load.

[0076] The vulcanizing agent is dicumyl peroxide;

[0077] Flame retardant 1 is diammonium hydrogen phosphate, zinc borate, dicyandiamide, and alumina trihydrate; the weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide, and alumina trihydrate is 4:1:1.2:0.12 (flame retardant 1 is used in Examples 1-8);

[0078] Flame retardant 2 is diammonium hydrogen phosphate, zinc borate, dicyandiamide and alumina trihydrate; the weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide and alumina trihydrate is 4:0.8:0.8:0.08 (flame retardant 2 is used in Example 9);

[0079] Flame retardant 3 is diammonium hydrogen phosphate, zinc borate, dicyandiamide, and alumina trihydrate; the weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide, and alumina trihydrate is 4:1.2:1.2:0.12 (flame retardant 3 is used in Example 10);

[0080] The compatibilizer is dioctyl phthalate;

[0081] The antioxidant is 2,2,4-trimethyl-1,2-dihydrovalerine;

[0082] The inorganic filler is nano-calcium carbonate.

[0083] Comparative Example 1

[0084] Based on the formulation and preparation method of elastomer P1, the difference is that the flame retardant used is 0 parts by weight, thus obtaining elastomer DP1.

[0085] Comparative Example 2

[0086] Based on the formulation and preparation method of elastomer P1, the difference is that the flame retardant used is the same weight of flame retardant 4 (flame retardant 4 is diammonium hydrogen phosphate, zinc borate and aluminum oxide trihydrate, and the weight ratio of diammonium hydrogen phosphate, zinc borate and aluminum oxide trihydrate is 4:1:0.12), thus obtaining elastomer DP2.

[0087] Comparative Example 3

[0088] Based on the formulation and preparation method of elastomer P1, the difference is that the flame retardant used is the same weight of flame retardant 5 (flame retardant 5 is diammonium hydrogen phosphate, zinc borate and dicyandiamide, and the weight ratio of diammonium hydrogen phosphate, zinc borate and dicyandiamide is 4:1:1.2), thus obtaining elastomer DP3.

[0089] Comparative Example 4

[0090] Based on the formulation and preparation method of elastomer P1, the difference is that the compatibilizer used is 0 parts by weight, thus obtaining elastomer DP4.

[0091] Comparative Example 5

[0092] Based on the formulation and preparation method of elastomer P1, the difference is that the inorganic filler used is 0 parts by weight, thus obtaining elastomer DP5.

[0093] Table 1

[0094]

[0095] Test case

[0096] The tensile strength, elongation at break, oil resistance and oxygen index of the above elastomers P1-P10 and DP1-DP5 were measured respectively, and the results are shown in Table 2.

[0097] Tensile strength and elongation at break were tested according to the methods in GB / T 528-2009.

[0098] Oil resistance: After soaking in machine oil, place in an oven at 125℃ for 70 hours.

[0099] The oxygen index was tested according to the method in ASTM 2863.

[0100] Table 2

[0101]

[0102] As can be seen from Table 2, the elastomer obtained by using the composition of the present invention can obtain suitable tensile strength, elongation at break, oil resistance and oxygen index, thus indicating that the elastomer obtained by the composition of the present invention has excellent mechanical properties, good oil resistance and flame retardant properties.

[0103] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composition for preparing a halogen-free flame-retardant thermoplastic elastomer, characterized by, The composition contains nitrile rubber, polypropylene, vulcanizing agent, flame retardant, compatibilizer and inorganic filler; wherein, relative to 100 parts by weight of the nitrile rubber, the content of the polypropylene is 20-80 parts by weight, the content of the vulcanizing agent is 0.05-2 parts by weight, the content of the flame retardant is 10-50 parts by weight, the content of the compatibilizer is 5-30 parts by weight, the content of the inorganic filler is 5-20 parts by weight, and the flame retardant contains diammonium hydrogen phosphate, zinc borate, dicyandiamide and aluminum oxide trihydrate.

2. The composition of claim 1, wherein, The content of the polypropylene is 30-60 parts by weight, the content of the vulcanizing agent is 0.1-1 part by weight, the content of the flame retardant is 30-40 parts by weight, the content of the compatibilizer is 10-20 parts by weight, and the content of the inorganic filler is 10-15 parts by weight, relative to 100 parts by weight of the nitrile rubber.

3. The composition of claim 1, wherein, The content of acrylonitrile structural units in the nitrile rubber is 15-45 wt%, preferably 20-40 wt%.

4. The composition according to any one of claims 1-3, wherein, The polypropylene is homopolymer polypropylene and / or copolymer polypropylene. Preferably, the vulcanizing agent is one or more of dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,4-bis(tert-butylperoxy diisopropyl)benzene, 1,3-bis(tert-butylperoxy diisopropyl)benzene, 2,5-dimethyl-2,5-(di-tert-butylperoxy)-3-hexyne, ethyl-3,3-di(tert-butylperoxy)butyrate, ethyl-3,3-di(tert-amylperoxy)butyrate, dibenzoyl peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, 1,1-di(tert-amylperoxy)cyclohexane and tert-butylperoxy benzoate.

5. The composition according to any one of claims 1-3, wherein, The weight ratio of diammonium hydrogen phosphate, zinc borate, dicyandiamide and aluminum oxide trihydrate is 4:(0.8-1.2):(0.8-1.2):(0.08-0.12).

6. The composition according to any one of claims 1-3, wherein, The compatibilizer is selected from one or more of dioctyl phthalate, polyol benzoate, trioctyl trimellitate and dioctyl sebacate.

7. The composition according to any one of claims 1-3, wherein, The inorganic filler is selected from one or more of kaolin, talc, calcium carbonate, white carbon black and carbon black.

8. The composition according to any one of claims 1-3, wherein, The composition further contains an antioxidant, and the content of the antioxidant is 1-7 parts by weight, preferably 1.5-5 parts by weight, relative to 100 parts by weight of the nitrile rubber.

9. The composition of claim 8, wherein, The antioxidant is selected from one or more of amine antioxidants, quinoline antioxidants and benzimidazole antioxidants.

10. A halogen-free flame-retardant thermoplastic elastomer characterized by, It is prepared by using the composition for preparing halogen-free flame-retardant thermoplastic elastomer of any one of claims 1-9 as raw material.

11. A process for the preparation of a halogen-free flame-retardant thermoplastic elastomer, characterized in that, It is prepared by using the composition for preparing halogen-free flame-retardant thermoplastic elastomer of any one of claims 1-9 as raw material.

12. The method of claim 11, wherein, The method comprises: 1) a step of mixing the nitrile rubber, the compatibilizer, the inorganic filler and optionally the antioxidant to obtain a masterbatch; 2) a step of extruding and granulating the masterbatch to obtain masterbatch particles; 3) a step of dynamically vulcanizing said masterbatch particles, said polypropylene, said vulcanizing agent and said flame retardant.

13. The method of claim 12, wherein, In step 1), the temperature of said mixing is comprised between 100 and 130°C; Preferably, in step 1), said mixing is carried out in an internal mixer.

14. The method of claim 12, wherein, In step 2), said extrusion granulation is carried out in a single screw extruder.

15. The method of claim 12, wherein, In step 3), said dynamic vulcanization is carried out in a co-rotating twin screw extruder; Preferably, in step 3), the conditions of said dynamic vulcanization comprise a screw rotation speed comprised between 100 and 600 rpm and a temperature comprised between 160 and 230°C.

16. A halogen-free flame-retardant thermoplastic elastomer characterized by, which is obtainable by the process for the preparation of a halogen-free flame-retardant thermoplastic elastomer according to any one of claims 11 to 15.

17. Use of the thermoplastic elastomer according to claims 10 and 16 for the preparation of fuel delivery lines and sealing parts.

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