Flame-retardant antistatic rubber material for conveying belt and preparation method of flame-retardant antistatic rubber material

Abstract

The invention discloses a flame-retardant antistatic rubber material for a conveying belt and a preparation method of the flame-retardant antistatic rubber material, and relates to the technical field of rubber materials. The rubber material is prepared from the following components: 40-80 parts of chloroprene rubber, 10-40 parts of butadiene rubber, 10-30 parts of high styrene rubber, 20-40 parts of a reinforcing agent, 15-30 parts of an antistatic agent, 10-30 parts of aluminum hydroxide, 10-20 parts of a modified flame retardant, 5-10 parts of polyethylene fibers, 5-10 parts of zinc stearate, 3-6 parts of a coupling agent, 4-8 parts of a vulcanizing agent, 1-3 parts of an accelerant and 1-3 parts of an anti-aging agent. Basic performance is provided through a compounding system of three kinds of rubber, the mechanical performance is improved by adopting an attapulgite-carbon black compounding reinforcing system, and the antistatic and flame-retardant functions are achieved in combination with the antistatic agent and the specially-made modified flame retardant.

Description

Technical Field

[0001] The invention relates to the technical field of rubber materials, and in particular to a flame-retardant and antistatic rubber material for a conveyor belt and a preparation method thereof. Background Art

[0002] As an important tool for material transportation in modern industry, conveyor belts are widely used in mining, chemical, port, power and other industries. Among them, rubber conveyor belts have become the most important type of conveyor belts due to their excellent mechanical strength, wear resistance and long service life. The typical rubber conveyor belt structure includes a skeleton layer and a covering rubber layer. The skeleton layer provides basic strength and stability, while the covering rubber layer directly contacts the conveyed material and undertakes protection and conveying functions.

[0003] The performance of rubber materials used in conveyor belts directly determines the use effect and safety of conveyor belts. Usually, this type of rubber material adopts a compound system of multiple rubbers, such as natural rubber, styrene-butadiene rubber, chloroprene rubber, etc. The selection and proportion of different types of rubber need to comprehensively consider their characteristics in terms of oil resistance, heat resistance, cold resistance, ozone aging resistance, etc. In order to meet the needs of specific applications, it is also necessary to adjust the material properties by adding various functional additives.

[0004] In recent years, with the advancement of global industrialization and rapid economic development, the application scope and demand of conveyor belts have continued to expand. However, in different application scenarios, conveyor belts face various stringent performance requirements. Especially in special environments such as underground coal mines, due to the presence of a large amount of flammable gas and poor air circulation, conveyor belts must not only have excellent mechanical properties and aging resistance, but also good flame retardant and antistatic properties. This requires rubber materials to have reliable flame retardant and antistatic properties while maintaining good physical and mechanical properties.

[0005] CN109206682A discloses a cold-resistant, flame-retardant and antistatic conveyor belt covering rubber, which comprises, by weight, 35 to 50 parts of natural rubber, 40 to 60 parts of butadiene rubber, 20 to 30 parts of chloroprene rubber, 20 to 30 parts of conductive carbon black, 25 to 35 parts of high wear-resistant carbon black, 10 to 15 parts of antimony trioxide, 5 to 10 parts of chlorinated paraffin, 8 to 15 parts of ammonium polyphosphate, 5 to 10 parts of flame-retardant softener, 1 to 2 parts of vulcanizing agent, and 1 to 2 parts of vulcanization accelerator. 2 parts, zinc oxide 3-6 parts, magnesium oxide 1-2 parts, rare earth oxide 10-16 parts, stearic acid 1-2 parts, antioxidant 2-4 parts, antioxidant 1-2 parts, adding conductive carbon black, increase the conductivity of the covering rubber layer, improve the antistatic ability, through antimony trioxide, paraffin wax, ammonium polyphosphate to achieve flame retardant effect, while the flame retardant softener improves the softness of the rubber cross-linking bonds, making up for the lack of rubber elasticity of the flame retardant conveyor belt under high cold conditions.

[0006] Although a variety of rubber compound systems are used in the commonly used rubber material formulas on the market, the compatibility and synergy between the components need to be improved. The following problems are common in the prior art: First, although conventional inorganic flame retardants have a certain flame retardant effect, they have poor compatibility with the rubber matrix and require a large amount of addition to achieve the ideal flame retardant effect, which seriously affects the mechanical properties of the material. Secondly, traditional antistatic agents have poor dispersibility in rubber and are prone to migration and precipitation, resulting in short-lasting antistatic performance. In addition, the selection and modification of the reinforcement system in the existing formula is not reasonable enough, making it difficult to achieve good mechanical strength and flexibility at the same time.

[0007] Especially in the selection of flame retardants, the existing technology mainly relies on simple physical mixing, lacking in-depth design and modification of the molecular structure of flame retardants. This leads to poor interface bonding between flame retardants and rubber matrix, and low flame retardant efficiency. At the same time, due to the failure to establish an effective synergistic flame retardant system, a large amount of addition is often required to meet the flame retardant requirements, which inevitably affects other properties of the material.

[0008] With the continuous improvement of industrial development requirements for conveyor belt performance, as well as the emergence of new requirements such as environmental protection and energy saving, it is urgent to develop a new type of flame-retardant and antistatic rubber material for conveyor belts. This material should achieve the synergistic improvement of multiple properties such as flame retardancy, antistatic properties, and mechanical properties by optimizing the rubber ratio system, designing and developing high-efficiency modified flame retardants, selecting appropriate reinforcing agents and antistatic agents, and establishing a scientific formulation system. At the same time, it is also necessary to ensure good compatibility and dispersibility between the various components to ensure the long-term stability of the material performance. Summary of the invention

[0009] In order to address the deficiencies in the prior art, the purpose of the present invention is to provide a flame-retardant and antistatic rubber material for conveyor belts and a preparation method thereof. The basic performance is provided by a compound system of three rubbers, a attapulgite-carbon black compound reinforcement system is used to improve the mechanical properties, and an antistatic agent and a specially modified flame retardant are combined to achieve antistatic and flame retardant functions. The modified flame retardant is obtained by modifying corundum with phytic acid and introducing DOPO to form a multiple synergistic flame retardant mechanism, while improving the mechanical properties and interfacial bonding strength of the rubber matrix, so that the comprehensive performance of the material reaches an ideal balance.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] A flame retardant and antistatic rubber material for a conveyor belt is made of the following components, measured by weight: 40 to 80 parts of chloroprene rubber, 10 to 40 parts of butadiene rubber, 10 to 30 parts of high styrene rubber, 20 to 40 parts of a reinforcing agent, 15 to 30 parts of an antistatic agent, 10 to 30 parts of aluminum hydroxide, 10 to 20 parts of a modified flame retardant, 5 to 10 parts of polyethylene fiber, 5 to 10 parts of zinc stearate, 3 to 6 parts of a coupling agent, 4 to 8 parts of a vulcanizing agent, 1 to 3 parts of an accelerator, and 1 to 3 parts of an antioxidant.

[0012] Preferably, the preparation method of the modified flame retardant comprises the following steps:

[0013] (1) adding phytic acid and 1,3-dihydroxyacetone to DMF, then adding p-toluenesulfonic acid, stirring and reacting under a nitrogen atmosphere, filtering the reaction solution, precipitating, and recrystallizing to obtain hydroxyacetone-modified phytate;

[0014] Esterification reaction of phytic acid and 1,3-dihydroxyacetone: Under nitrogen protection, p-toluenesulfonic acid is used as an acid catalyst to start the reaction. First, the P=O group in the phytic acid molecule is protonated to enhance the electrophilicity of the phosphorus atom and form a more active electrophilic center. Subsequently, the primary hydroxyl group (-CH2OH) in the 1,3-dihydroxyacetone molecule acts as a nucleophilic reagent, and its lone pair of electrons attacks the activated phosphorus center, undergoes a tetrahedral transition state, and then undergoes intramolecular proton transfer, and finally removes the water molecule to form a new POC ester bond.

[0015] Preferably, in step (1), the usage ratio of phytic acid, 1,3-dihydroxyacetone, tetrahydrofuran and p-toluenesulfonic acid is 2.5-4.5 g: 0.8-1.5 g: 60-120 mL: 0.05-0.15 g.

[0016] Preferably, in step (1), the stirring reaction condition is 45-65° C. for 5-10 hours; after the reaction is completed, the reaction solution is poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain hydroxyacetone modified phytate.

[0017] (2) adding hydroxyacetone-modified phytate and DOPO to DMF, then adding triethylamine, stirring and reacting under a nitrogen atmosphere, filtering, precipitating, and recrystallizing the reaction solution to obtain a modifier;

[0018] Reaction of hydroxyacetone-modified phytate with DOPO: triethylamine, as a base catalyst, first captures the proton of the PH bond in the DOPO molecule to generate a phosphorus anion intermediate with strong nucleophilicity. This active intermediate then undergoes nucleophilic addition to the carbonyl group (C=O) in the first step product (hydroxyacetone-modified phytate) molecule, with the phosphorus atom attacking the carbonyl carbon atom to form a new PC bond, while the carbonyl oxygen atom acquires a negative charge. This intermediate is then protonated to complete the addition reaction.

[0019] Preferably, in step (2), the usage ratio of hydroxyacetone-modified phytate, DOPO, DMF and triethylamine is 2.0-3.5 g: 1.5-2.2 g: 60-120 mL: 0.08-0.15 mL.

[0020] Preferably, in step (2), the stirring reaction conditions are 20-30° C. for 8-14 hours; after the reaction is completed, the reaction solution is poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain a modifier.

[0021] (3) After the corundum is dried in vacuum, it is added to DMF, and then a modifier is added. The temperature is raised under a nitrogen atmosphere to react, and the product is filtered, washed, and dried to obtain a modified flame retardant.

[0022] Modifier grafting to the surface of corundum: First, the silicon hydroxyl groups (Si-OH) on the surface of corundum are activated by high-temperature vacuum treatment to make it more reactive. Under high temperature conditions, the phosphate groups in the modifier molecules (P-OH from the phytic acid skeleton) react with the activated surface silicon hydroxyl groups to form Si-OP covalent bonds through dehydration. This is a typical surface chemical reaction, and the reaction rate is controlled by diffusion, and a long time is required to ensure sufficient grafting. Since the phytic acid molecule has multiple phosphate groups, each molecule may form multiple connection points with the surface of corundum, which enhances the grafting stability.

[0023] Preferably, in step (3), the particle size of corundum is 500-800 mesh; the usage ratio of corundum, DMF and modifier is 15-25 g: 100-200 mL: 3-7.2 g.

[0024] Preferably, in step (3), the temperature reaction conditions are 200-400 r / min, 110-130° C. for 18-30 hours; after the reaction is completed, the product is filtered, washed three times with DMF, anhydrous ethanol and acetone in sequence, and vacuum dried to obtain a modified flame retardant.

[0025] Preferably, the reinforcing agent is formed by mixing attapulgite and carbon black in a mass ratio of 1:2 to 4, and the particle size of the attapulgite is 800 to 1200 meshes.

[0026] Preferably, the antistatic agent is one or more of quaternary ammonium salts, alcohol amines, sulfonates, and polyether antistatic agents.

[0027] Preferably, the coupling agent is one or more of KH550, KH560, and KH570.

[0028] Preferably, the vulcanizing agent is one or more of dicumyl peroxide, benzoyl peroxide, and sulfur.

[0029] Preferably, the accelerator is one or more of tetramethylthiuram disulfide, dibenzothiazole disulfide, and zinc dibutyldithiocarbamate.

[0030] Preferably, the antioxidant is N-phenyl-2-naphthylamine and / or N,N'-di(β-naphthyl)-p-phenylenediamine.

[0031] The present invention also claims protection for a method for preparing the flame retardant and antistatic rubber material for the conveyor belt, comprising the following steps: mixing the raw materials in parts by weight, adding them into an open rubber mixer for mixing, then placing them into a flat vulcanizer for vulcanization and molding, soaking them in water, and finally drying them to constant weight to obtain the flame retardant and antistatic rubber material for the conveyor belt.

[0032] Preferably, the mixing conditions are mixing at 45-55°C for 20-30 minutes; the vulcanization molding includes two-stage vulcanization, the first stage vulcanization conditions are 165-185°C, 10-15MPa for 20-30 minutes, and the second stage vulcanization conditions are 170-180°C, 12-16MPa for 2-3 hours; soak in water for 3-6 hours, and dry at 95-105°C to constant weight.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention provides a flame-retardant and antistatic rubber material for conveyor belts. In the compounding system of three rubbers, chloroprene rubber contains chlorine and has excellent flame retardancy, oil resistance and aging resistance; butadiene rubber gives the material good elasticity and wear resistance, while improving the processing fluidity of the material; high styrene rubber improves the hardness and tear resistance of the material. In the reinforcement system, attapulgite has a unique tubular structure and a large specific surface area, which can significantly improve the mechanical strength of the material, and the reinforcing effect of carbon black can further enhance the tensile strength and wear resistance of the material. The addition of antistatic agent effectively reduces the surface resistance of the material and prevents static electricity accumulation; aluminum hydroxide, as an inorganic flame retardant, decomposes at high temperature to absorb heat and release water molecules, forming a synergistic flame retardant effect with the modified flame retardant. The addition of polyethylene fiber improves the toughness and tear resistance of the material; the use of zinc stearate and coupling agent improves the compatibility and interfacial bonding between the components; the vulcanization system (vulcanizing agent, accelerator) ensures the complete cross-linking of the material, and the addition of antioxidant extends the service life of the material. This multi-component formula design enables the material to achieve an ideal balance in flame retardancy, antistatic properties, mechanical properties and durability.

[0035] 2. The present invention provides a method for preparing a modified flame retardant, firstly, hydroxyacetone modified phytate is obtained by esterification reaction of phytic acid and 1,3-dihydroxyacetone, then the modifier is obtained by addition reaction with DOPO, and finally the modifier is condensed with the silicon hydroxyl group on the surface of corundum through the phosphoric acid group to achieve surface modification. The whole preparation process has mild reaction conditions, simple operation, and the product is easy to separate and purify.

[0036] 3. The present invention provides a modified flame retardant. First, corundum as an inorganic skeleton not only provides excellent wear resistance, but also significantly improves the interfacial compatibility and dispersibility with the rubber matrix after its surface is modified by phytic acid, and effectively inhibits the agglomeration of inorganic substances. Secondly, the hexafunctional phytic acid molecules are loaded on the surface of corundum through multi-point chemical bonding, and can construct a three-dimensional network structure in the rubber matrix, promote the cross-linking and curing process of the rubber, and improve the mechanical strength of the composite material. In terms of flame retardancy, the modified flame retardant works through multiple mechanisms: the phosphorus element provided by phytic acid decomposes at high temperature to produce active free radicals, which can effectively capture unstable free radicals in the combustion process. At the same time, the three-dimensional network structure formed by it increases the melt strength of the matrix material and inhibits the droplet phenomenon; the phosphorus oxygen structure in the DOPO molecule can produce a large number of PO· free radicals during combustion, and effectively inhibits the combustion chain reaction through gas phase flame retardancy. More importantly, the synergistic effect of phytic acid and DOPO not only enhances the gas phase flame retardant effect, but also forms a denser and more stable phosphorylated carbon layer on the surface of the rubber material, significantly improving the flame retardant properties of the material. This multiple synergistic mechanism enables the modified flame retardant to not only enhance the flame retardant properties of the material, but also significantly improve the mechanical properties and processing properties of the rubber material. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show schematic diagrams of certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a curve diagram of the total amount of heat release of the embodiments and comparative examples. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0040] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from raw materials purchased from commercial sources.

[0041] A method for preparing a flame retardant and antistatic rubber material for a conveyor belt comprises the following steps:

[0042] (1) adding 2.5-4.5 g of phytic acid and 0.8-1.5 g of 1,3-dihydroxyacetone to 60-120 mL of DMF, and then adding 0.05-0.15 g of p-toluenesulfonic acid, stirring and reacting for 5-10 h at 45-65° C. in a nitrogen atmosphere. After the reaction is completed, pouring the reaction solution into ice water, filtering, precipitating, and recrystallizing with ethanol to obtain hydroxyacetone-modified phytic acid ester;

[0043] (2) adding 2.0-3.5 g of hydroxyacetone-modified phytate and 1.5-2.2 g of DOPO to 60-120 mL of DMF, and then adding 0.08-0.15 mL of triethylamine, stirring and reacting for 8-14 h at 20-30° C. in a nitrogen atmosphere. After the reaction is completed, pouring the reaction solution into ice water, filtering, precipitating, and recrystallizing with ethanol to obtain a modifier;

[0044] (3) 15-25 g of corundum is vacuum dried and added to 100-200 mL of DMF, followed by adding 3-7.2 g of a modifier, and reacting for 18-30 h at 200-400 r / min and 110-130° C. in a nitrogen atmosphere. After the reaction is completed, the product is filtered, washed three times with DMF, anhydrous ethanol, and acetone in sequence, and vacuum dried to obtain a modified flame retardant;

[0045] (4) 40 to 80 parts of chloroprene rubber, 10 to 40 parts of butadiene rubber, 10 to 30 parts of high styrene rubber, and a reinforcing agent (mixed with attapulgite and carbon black in a mass ratio of 1:2 to 4)

[0046] The flame retardant and antistatic rubber material for the conveyor belt is prepared by mixing 20 to 40 parts of propylene glycol, 15 to 30 parts of antistatic agent, 10 to 30 parts of aluminum hydroxide, 10 to 20 parts of modified flame retardant, 5 to 10 parts of polyethylene fiber, 5 to 10 parts of zinc stearate, 3 to 6 parts of coupling agent, 4 to 8 parts of vulcanizing agent, 1 to 3 parts of accelerator and 1 to 3 parts of antioxidant, adding the mixture into an open rubber mixer and mixing at 45 to 55° C. for 20 to 30 minutes, then putting the mixture into a flat vulcanizing press, vulcanizing at 165 to 185° C. and 10 to 15 MPa for 20 to 30 minutes, then vulcanizing at 170 to 180° C. and 12 to 16 MPa for 2 to 3 hours, soaking the mixture in water for 3 to 6 hours, and finally drying the mixture at 95 to 105° C. to a constant weight, to obtain the flame retardant and antistatic rubber material for the conveyor belt.

[0047] The antistatic agent is one or more of quaternary ammonium salts, alcohol amines, sulfonates and polyether antistatic agents.

[0048] The coupling agent is one or more of KH550, KH560, and KH570.

[0049] The vulcanizing agent is one or more of dicumyl peroxide, benzoyl peroxide and sulfur.

[0050] The accelerator is one or more of tetramethylthiuram disulfide, dibenzothiazole disulfide, and zinc dibutyldithiocarbamate.

[0051] The antioxidant is N-phenyl-2-naphthylamine and / or N,N'-di(β-naphthyl)-p-phenylenediamine.

[0052] The present invention will be further described below through specific embodiments.

[0053] Example 1

[0054] A method for preparing a flame retardant and antistatic rubber material for a conveyor belt comprises the following steps:

[0055] (1) 4.5 g of phytic acid and 1.5 g of 1,3-dihydroxyacetone were added to 100 mL of DMF, and then 0.15 g of p-toluenesulfonic acid was added, and the mixture was stirred at 65° C. for 5 h under a nitrogen atmosphere. After the reaction, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain hydroxyacetone-modified phytate;

[0056] (2) 3.5 g of hydroxyacetone-modified phytate and 2.2 g of DOPO were added to 100 mL of DMF, followed by 0.15 mL of triethylamine, and the mixture was stirred at 30 °C for 8 h under a nitrogen atmosphere. After the reaction, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain a modifier;

[0057] (3) 25 g of corundum was vacuum dried and added to 150 mL of DMF, followed by adding 7.2 g of a modifier, and reacted for 18 h at 400 r / min and 130° C. in a nitrogen atmosphere. After the reaction was completed, the product was filtered, washed three times with DMF, anhydrous ethanol, and acetone in sequence, and vacuum dried to obtain a modified flame retardant;

[0058] (4) 800 g of chloroprene rubber, 400 g of butadiene rubber, 300 g of high styrene rubber, 400 g of reinforcing agent (mixed by attapulgite and carbon black in a mass ratio of 1:3), 300 g of antistatic agent octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate, 300 g of aluminum hydroxide, 200 g of modified flame retardant, 100 g of polyethylene fiber, 100 g of zinc stearate, and coupling agent KH550 were added. The mixture was mixed with 60g of 1,2-diisopropylbenzene peroxide as a vulcanizing agent, 80g of tetramethylthiuram disulfide as an accelerator, and 30g of N-phenyl-2-naphthylamine as an antioxidant, added into an open rubber mixer and mixed for 25min at 50°C, then put into a flat vulcanizing machine, vulcanized for 25min at 180°C and 12MPa, then vulcanized for 2.5h at 175°C and 14MPa, immersed in water for 5h, and finally dried at 102°C to constant weight to obtain the flame retardant and antistatic rubber material for conveyor belts.

[0059] Example 2

[0060] A method for preparing a flame retardant and antistatic rubber material for a conveyor belt comprises the following steps:

[0061] (1) 4 g of phytic acid and 1.2 g of 1,3-dihydroxyacetone were added to 100 mL of DMF, and then 0.12 g of p-toluenesulfonic acid was added, and the mixture was stirred at 60° C. for 6 h under a nitrogen atmosphere. After the reaction, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain hydroxyacetone-modified phytate;

[0062] (2) 3 g of hydroxyacetone-modified phytate and 2.0 g of DOPO were added to 100 mL of DMF, followed by 0.12 mL of triethylamine. The mixture was stirred and reacted at 28 °C under a nitrogen atmosphere for 10 h. After the reaction, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain a modifier.

[0063] (3) 20 g of corundum was vacuum dried and added to 150 mL of DMF, followed by the addition of 6.8 g of a modifier, and the mixture was reacted at 300 r / min and 120° C. in a nitrogen atmosphere for 22 h. After the reaction was completed, the product was filtered, washed three times with DMF, anhydrous ethanol, and acetone in sequence, and vacuum dried to obtain a modified flame retardant;

[0064] (4) 700 g of chloroprene rubber, 300 g of butadiene rubber, 200 g of high styrene rubber, 300 g of reinforcing agent (mixed by attapulgite and carbon black in a mass ratio of 1:3), 200 g of antistatic agent octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate, 200 g of aluminum hydroxide, 150 g of modified flame retardant, 80 g of polyethylene fiber, 80 g of zinc stearate, and coupling agent KH560 were added. The mixture is mixed with 50g of 1% tungsten carboxylic acid, 70g of benzoyl peroxide vulcanizing agent, 20g of dibenzothiazole disulfide accelerator, and 20g of N-phenyl-2-naphthylamine antioxidant, added into an open rubber mixer and kneaded at 50°C for 25min, then put into a flat vulcanizing press, vulcanized at 180°C and 12MPa for 25min, then vulcanized at 175°C and 14MPa for 2.5h, soaked in water for 5h, and finally dried at 102°C to constant weight to obtain the flame retardant and antistatic rubber material for the conveyor belt.

[0065] Example 3

[0066] A method for preparing a flame retardant and antistatic rubber material for a conveyor belt comprises the following steps:

[0067] (1) 3.5 g of phytic acid and 1.0 g of 1,3-dihydroxyacetone were added to 100 mL of DMF, and then 0.1 g of p-toluenesulfonic acid was added, and the mixture was stirred at 55° C. for 8 h under a nitrogen atmosphere. After the reaction was completed, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain hydroxyacetone-modified phytate;

[0068] (2) 2.5 g of hydroxyacetone-modified phytate and 1.8 g of DOPO were added to 100 mL of DMF, followed by 0.10 mL of triethylamine. The mixture was stirred at 24 °C for 12 h under a nitrogen atmosphere. After the reaction, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain a modifier.

[0069] (3) 20 g of corundum was vacuum dried and added to 150 mL of DMF, followed by the addition of 5 g of a modifier, and the mixture was reacted for 26 h at 300 r / min and 120° C. in a nitrogen atmosphere. After the reaction was completed, the product was filtered, washed three times with DMF, anhydrous ethanol, and acetone in sequence, and vacuum dried to obtain a modified flame retardant;

[0070] (4) 500 g of chloroprene rubber, 200 g of butadiene rubber, 200 g of high styrene rubber, 300 g of reinforcing agent (mixed by attapulgite and carbon black in a mass ratio of 1:3), 200 g of antistatic agent octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate, 200 g of aluminum hydroxide, 120 g of modified flame retardant, 70 g of polyethylene fiber, 70 g of zinc stearate, and coupling agent KH570 were added. The mixture is mixed with 40g of sulphur vulcanizing agent, 50g of sulfur, 15g of accelerator dibutyl dithiocarbamate zinc, and 15g of antioxidant N, N'-di(β-naphthyl)-p-phenylenediamine, added into an open rubber mixer and kneaded for 25min at 50°C, then put into a flat vulcanizing press, vulcanized for 25min at 180°C and 12MPa, then vulcanized for 2.5h at 175°C and 14MPa, soaked in water for 5h, and finally dried at 102°C to constant weight to obtain the flame retardant and antistatic rubber material for the conveyor belt.

[0071] Example 4

[0072] A method for preparing a flame retardant and antistatic rubber material for a conveyor belt comprises the following steps:

[0073] (1) 2.5 g of phytic acid and 0.8 g of 1,3-dihydroxyacetone were added to 100 mL of DMF, and then 0.05 g of p-toluenesulfonic acid was added, and the mixture was stirred at 45° C. for 10 h under a nitrogen atmosphere. After the reaction, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain hydroxyacetone-modified phytate;

[0074] (2) 2.0 g of hydroxyacetone-modified phytate and 1.5 g of DOPO were added to 100 mL of DMF, followed by 0.08 mL of triethylamine. The mixture was stirred at 20 °C for 14 h under a nitrogen atmosphere. After the reaction, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain a modifier.

[0075] (3) 15 g of corundum was vacuum dried and added to 150 mL of DMF, followed by the addition of 3 g of a modifier, and the mixture was reacted for 30 h at 200 r / min and 110° C. in a nitrogen atmosphere. After the reaction was completed, the product was filtered, washed three times with DMF, anhydrous ethanol, and acetone in sequence, and vacuum dried to obtain a modified flame retardant;

[0076] (4) 400 g of chloroprene rubber, 100 g of butadiene rubber, 100 g of high styrene rubber, 200 g of reinforcing agent (mixed by attapulgite and carbon black in a mass ratio of 1:3), 150 g of antistatic agent octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate, 100 g of aluminum hydroxide, 100 g of modified flame retardant, 50 g of polyethylene fiber, 50 g of zinc stearate, and coupling agent KH570 were added. The mixture is mixed with 30g of 1,4-dibenzothiazole disulfide, 40g of vulcanizing agent, 10g of accelerator dibenzothiazole disulfide, and 10g of antioxidant N,N'-di(β-naphthyl)-p-phenylenediamine, added into an open rubber mixer and kneaded at 50°C for 25min, then put into a flat vulcanizer, vulcanized at 180°C and 12MPa for 25min, then vulcanized at 175°C and 14MPa for 2.5h, soaked in water for 5h, and finally dried at 102°C to constant weight to obtain the flame retardant and antistatic rubber material for the conveyor belt.

[0077] Comparative Example 1

[0078] A method for preparing a rubber material for a conveyor belt comprises the following steps:

[0079] (1) 4.5 g of phytic acid and 1.5 g of 1,3-dihydroxyacetone were added to 100 mL of DMF, and then 0.15 g of p-toluenesulfonic acid was added, and the mixture was stirred at 65° C. for 5 h under a nitrogen atmosphere. After the reaction, the reaction solution was poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain hydroxyacetone-modified phytate;

[0080] (2) 25 g of corundum was vacuum dried and added to 150 mL of DMF, followed by the addition of 7.2 g of hydroxyacetone-modified phytate, and the reaction was carried out at 400 r / min and 130° C. in a nitrogen atmosphere for 18 h. After the reaction was completed, the product was filtered, washed three times with DMF, anhydrous ethanol, and acetone in sequence, and vacuum dried to obtain a modified flame retardant;

[0081] (3) 800 g of chloroprene rubber, 400 g of butadiene rubber, 300 g of high styrene rubber, 400 g of reinforcing agent (mixed by attapulgite and carbon black in a mass ratio of 1:3), 300 g of antistatic agent octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate, 300 g of aluminum hydroxide, 200 g of modified flame retardant, 100 g of polyethylene fiber, 100 g of zinc stearate, and coupling agent KH550 were added. The mixture is mixed with 60g of 1,2-diisopropylbenzene peroxide, 80g of vulcanizing agent diisopropylbenzene peroxide, 30g of accelerator tetramethylthiuram disulfide, and 30g of antioxidant N-phenyl-2-naphthylamine, added into an open rubber mixer and kneaded for 25min at 50°C, then put into a flat vulcanizer, vulcanized for 25min at 180°C and 12MPa, then vulcanized for 2.5h at 175°C and 14MPa, immersed in water for 5h, and finally dried at 102°C to constant weight to obtain the rubber material for the conveyor belt.

[0082] Comparative Example 2

[0083] A method for preparing a rubber material for a conveyor belt comprises the following steps:

[0084] 800g of chloroprene rubber, 400g of butadiene rubber, 300g of high styrene rubber, 400g of reinforcing agent (formed by mixing attapulgite and carbon black in a mass ratio of 1:3), 300g of antistatic agent octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate, 300g of aluminum hydroxide, 200g of corundum, 100g of polyethylene fiber, 100g of zinc stearate, 60g of coupling agent KH550, 80g of vulcanizing agent diisopropylbenzene peroxide, 30g of accelerator tetramethylthiuram disulfide, and 30g of antioxidant N-phenyl-2-naphthylamine were mixed, added to an open rubber mixer and mixed at 50°C for 25min, then put into a flat vulcanizer, vulcanized at 180°C and 12MPa for 25min, then vulcanized at 175°C and 14MPa for 2.5h, soaked in water for 5h, and finally dried at 102°C to constant weight to obtain the rubber material for the conveyor belt.

[0085] The rubber materials for conveyor belts prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were tested for performance. The Shore hardness was tested with an LX-A type Shore rubber hardness tester according to GB / T 2411-2008 "Determination of indentation hardness (Shore hardness) of plastics and hard rubber using a hardness tester"; the mechanical properties were tested with reference to GB / T 1040.1-2018 "Determination of tensile properties of plastics Part 1: General"; the limiting oxygen index and flame retardant properties were tested with reference to ISO 4589-2 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test"; the surface resistivity at 20°C and relative humidity of 60% was tested with reference to GB / T 2439-2001 "Determination of electrical conductivity and dissipative properties of vulcanized rubber or thermoplastic rubber". Specific data are shown in Table 1.

[0086] Table 1 Performance test results of rubber materials for conveyor belts

[0087] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Shore hardness(A) 72.5 68.5 71 68 73 78 Tensile strength(MPa) 4.13 4.56 4.19 4.62 3.94 3.61 Elongation at break (%) 316 327 307 339 285 263 Flame retardant properties V0 V0 V0 V0 V1 V2 Limiting oxygen index (%) 37.5 35.3 37.9 35.8 29.4 26.7 Surface resistivity(Ω) <![CDATA[0.16×10 8 ]]> <![CDATA[0.23×10 8 ]]> <![CDATA[0.94×10 7 ]]> <![CDATA[0.83×10 7 ]]> <![CDATA[0.52×10 8 ]]> <![CDATA[0.89×10 8 ]]>

[0088] The total heat release (THR) of the sample in the range of 100 to 600 °C was tested using an American Govmark MCC-2 microcalorimeter. The sample size was 100 × 10 × 10 mm. 3 , the sample mass is 5-8 mg, see Figure 1 .

[0089] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A flame retardant and antistatic rubber material for a conveyor belt, characterized in that: The invention is made of the following components in parts by weight: 40-80 parts of chloroprene rubber, 10-40 parts of butadiene rubber, 10-30 parts of high styrene rubber, 20-40 parts of reinforcing agent, 15-30 parts of antistatic agent, 10-30 parts of aluminum hydroxide, 10-20 parts of modified flame retardant, 5-10 parts of polyethylene fiber, 5-10 parts of zinc stearate, 3-6 parts of coupling agent, 4-8 parts of vulcanizing agent, 1-3 parts of accelerator and 1-3 parts of antioxidant.

2. The flame retardant and antistatic rubber material for conveyor belts according to claim 1, characterized in that: The preparation method of the modified flame retardant comprises the following steps: (1) adding phytic acid and 1,3-dihydroxyacetone to DMF, then adding p-toluenesulfonic acid, stirring and reacting under a nitrogen atmosphere, filtering the reaction solution, precipitating, and recrystallizing to obtain hydroxyacetone-modified phytate; (2) adding hydroxyacetone-modified phytate and DOPO to DMF, then adding triethylamine, stirring and reacting under a nitrogen atmosphere, filtering, precipitating, and recrystallizing the reaction solution to obtain a modifier; (3) After the corundum is dried in vacuum, it is added to DMF, and then a modifier is added. The temperature is raised under a nitrogen atmosphere to react, and the product is filtered, washed, and dried to obtain a modified flame retardant.

3. The flame retardant and antistatic rubber material for conveyor belts according to claim 1, characterized in that: In step (1), the usage ratio of phytic acid, 1,3-dihydroxyacetone, tetrahydrofuran and p-toluenesulfonic acid is 2.5-4.5 g: 0.8-1.5 g: 60-120 mL: 0.05-0.15 g.

4. The flame retardant and antistatic rubber material for conveyor belts according to claim 1, characterized in that: In step (1), the stirring reaction condition is 45-65° C. for 5-10 hours. After the reaction is completed, the reaction solution is poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain hydroxyacetone modified phytate.

5. The flame retardant and antistatic rubber material for conveyor belts according to claim 1, characterized in that: In step (2), the usage ratio of hydroxyacetone-modified phytate, DOPO, DMF and triethylamine is 2.0-3.5 g: 1.5-2.2 g: 60-120 mL: 0.08-0.15 mL.

6. The flame retardant and antistatic rubber material for conveyor belts according to claim 1, characterized in that: In step (2), the stirring reaction conditions are 20-30° C. for 8-14 hours. After the reaction is completed, the reaction solution is poured into ice water, filtered, precipitated, and recrystallized with ethanol to obtain a modifier.

7. The flame retardant and antistatic rubber material for conveyor belts according to claim 1, characterized in that: In step (3), the particle size of corundum is 500-800 mesh; the usage ratio of corundum, DMF and modifier is 15-25g:100-200mL:3-7.2g.

8. The flame retardant and antistatic rubber material for conveyor belts according to claim 1, characterized in that: In step (3), the temperature reaction conditions are 200-400 r / min, 110-130° C. for 18-30 hours; after the reaction is completed, the product is filtered, washed three times with DMF, anhydrous ethanol and acetone in sequence, and vacuum dried to obtain a modified flame retardant.

9. A method for preparing the flame retardant and antistatic rubber material for conveyor belts according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing the raw materials by weight, adding them into an open rubber mixer for mixing, then putting them into a flat vulcanizing machine for vulcanization and molding, soaking them in water, and finally drying them to constant weight to obtain the flame-retardant and antistatic rubber material for the conveyor belt.

10. The preparation method according to claim 9, characterized in that: The mixing conditions are mixing at 45-55°C for 20-30 minutes; the vulcanization molding includes two-stage vulcanization, the first stage vulcanization conditions are 165-185°C, 10-15MPa for 20-30 minutes, and the second stage vulcanization conditions are 170-180°C, 12-16MPa for 2-3 hours; soak in water for 3-6 hours, and dry at 95-105°C to constant weight.

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