A heat-resistant conveyor belt

Abstract

This application relates to conveyor belts, specifically a heat-resistant conveyor belt. Its raw materials, in parts by mass, include the following components: 100 parts of styrene-butadiene block copolymer; 20-30 parts of styrene-butadiene-phenyl-substituted acrylic monomer block copolymer; 10-20 parts of carbon black; and 0.1-0.5 parts of phenylsuccinic acid. This heat-resistant conveyor belt exhibits excellent mechanical properties and superior heat resistance compared to commercially available products. After aging at 200°C, it maintains excellent mechanical properties, maintaining high levels of tensile strength, elongation at break, wear resistance, permanent set at break, and hardness.

Description

Technical Field

[0001] The present application relates to a conveyor belt, and in particular to a heat-resistant conveyor belt. Background Art

[0002] With the development of my country's coal, cement, steel and other fields, the performance requirements for conveyor belts are also constantly increasing. At present, in many fields in my country, the temperature of materials transported by conveyor belts is above 200℃, and in some cases even above 600℃, which puts forward new requirements for the high temperature resistance of conveyor belts.

[0003] In existing technology, heat-resistant conveyor belts are typically manufactured using a mixture of styrene-butadiene rubber (SBR) and carbon black. SBR decomposes at a temperature of 285-310°C. As an unsaturated rubber, the aromatic groups in its molecular chain act as a shield, reducing the activity of double bonds, resulting in a certain degree of heat resistance. However, SBR itself has poor strength, necessitating the addition of carbon black as a reinforcing agent. Generally, the operating temperature of SBR does not exceed 150°C, making it difficult to meet practical requirements in some situations. Summary of the Invention

[0004] The present application relates to a heat-resistant conveyor belt, which has good mechanical properties and better heat resistance than products on the market. After aging treatment at 200°C, it can maintain good mechanical properties, and its tensile strength, elongation at break, wear resistance, permanent deformation at break, hardness and other parameters can all be maintained at a high level.

[0005] The heat-resistant conveyor belt involved in this application comprises the following components in parts by mass:

[0006] 100 parts of styrene-butadiene block copolymer

[0007] 20-30 parts of styrene-butadiene-phenyl substituted acrylic monomer block copolymer

[0008] 10-20 parts carbon black

[0009] 0.1-0.5 parts of phenylsuccinic acid.

[0010] In the above technical solution, a styrene-butadiene-phenyl-substituted acrylate monomer block copolymer is added to the styrene-butadiene rubber. This block copolymer, based on the styrene-butadiene rubber, incorporates a phenyl-substituted acrylate monomer. This block copolymer further enhances heat resistance through the rigidity of the benzene ring. Simultaneously, the acrylate monomer chain enhances the flexibility of the molecular chain within the system, significantly improving weather resistance. Phenylsuccinic acid acts as a bridge within the system, and its aromatic ring system further enhances the rigidity of the rubber, thereby further improving overall heat resistance.

[0011] Preferably, in the styrene-butadiene-phenyl-substituted acrylic monomer block copolymer, the molar ratio of the three monomers of styrene, butadiene and phenyl-substituted acrylic monomer is 100:50-80:10-30.

[0012] Preferably, the phenyl-substituted acrylic monomer is any number of methyl cinnamate, ethyl cinnamate, propyl cinnamate, and butyl cinnamate. More preferably, the phenyl-substituted acrylic monomer is methyl cinnamate.

[0013] Preferably, the number average molecular weight of the styrene-butadiene-phenyl substituted acrylic monomer block copolymer is 100,000 to 500,000. The number average molecular weight can be controlled by reaction time, reaction pressure and reaction temperature. Generally, extending the reaction time helps to increase the molecular weight.

[0014] Optionally, the raw materials of the heat-resistant transmission belt further include 3 to 8 parts by mass of silicone rubber. Preferably, the viscosity of the silicone rubber is 100,000 to 1,000,000.

[0015] The addition of high-viscosity silicone rubber improves thermal stability. During the molding process, the silane structure enhances heat resistance and surface strength. Furthermore, the addition of silicone rubber also improves cohesion, resulting in greater mechanical strength for the conveyor belt.

[0016] Preferably, the raw materials of the heat-resistant transmission belt further include 0.5 to 3 parts by mass of a cationic surfactant.

[0017] Preferably, the raw materials of the heat-resistant transmission belt further include 0.05 to 0.1 parts by mass of a coupling agent.

[0018] The coupling agent can improve the internal cross-linking structure, while increasing the tightness of the bonding between the organic phase and the inorganic phase, further improving the heat resistance.

[0019] Preferably, the raw materials of the heat-resistant transmission belt further include 1 to 10 parts by mass of polyphosphazene.

[0020] Polyphosphazene is a resin with good heat resistance. In the solution of the present application, adding 1 to 10 parts of polyphosphazene can improve the heat resistance without adversely affecting the overall mechanical properties.

[0021] In addition, on the basis of the present application, other heat-resistant additives may be added to further improve the heat resistance, which does not conflict with the solution of the present application.

[0022] In summary, the present application provides a transmission belt with good heat resistance, which has good weather resistance at high temperatures. DETAILED DESCRIPTION

[0023] The technical solution of this application is described through the following specific implementation methods.

[0024] First, a block copolymer of styrene, butadiene, and phenyl-substituted acrylic monomers was prepared according to the following preparation example.

[0025] Preparation Example: Preparation of a block copolymer of styrene, butadiene, and phenyl-substituted acrylic monomers. The specific preparation method is as follows:

[0026] In a reaction flask, add cyclohexane, styrene and a small amount of tetrahydrofuran, slowly add an initiating amount of n-butyl lithium to the system until the solution turns red, then react at 50°C for 1 hour, add the prepared butadiene cyclohexane solution dropwise to the above system within 30 minutes, continue to react for 2 hours, then cool to 20°C, add phenyl-substituted acrylic monomer, and add lithium chloride, continue to react for 2 hours, then evaporate the solvent, repeatedly wash with ethanol and cyclohexane, and obtain the target product after vacuum drying.

[0027] The molecular weight of the above compounds was determined using an Aters-150C gel permeation chromatograph. The molar ratio of each monomer in the molecule was estimated based on the initial charge amount.

[0028] First, methyl cinnamate was fixedly selected, and the addition amounts of the three monomers were changed to obtain the preparation examples shown in Table 1.

[0029]

[0030] Subsequently, on the basis of A-3, methyl cinnamate was replaced with other components in equal amounts, as shown in Table 2.

[0031]

[0032] Subsequently, based on A-3, by adjusting the reaction time of each step, and adjusting the amount of cyclohexane used and the reaction time of each step, block copolymers with different molecular weights and similar monomer molar ratios can be prepared.

[0033]

[0034] Example 1, a heat-resistant transmission belt is prepared by configuring raw materials according to the following mass ratio:

[0035] 100 parts of styrene-butadiene block copolymer

[0036] 30 parts of styrene-butadiene-phenyl substituted acrylic monomer block copolymer

[0037] 20 parts of carbon black

[0038] 0.5 parts of phenylsuccinic acid

[0039] 5 parts silicone rubber

[0040] 1 part cationic surfactant

[0041] 0.1 parts of coupling agent.

[0042] The styrene-butadiene-phenyl substituted acrylic monomer block copolymer is the product prepared in Preparation Example A-1.

[0043] The viscosity of silicone rubber is 1000000.

[0044] The cationic surfactant was cetyltrimethylammonium bromide.

[0045] The coupling agent is silane coupling agent KH-550.

[0046] The preparation method is as follows:

[0047] The styrene-butadiene block copolymer and the styrene-butadiene-phenyl substituted acrylic monomer block copolymer were mixed and rolled, and then other auxiliary materials were added and mixed for 20 minutes, and then cut into samples.

[0048] The above-mentioned samples can be coated on the surface of the skeleton material of the conveyor belt to form a conveyor belt. To facilitate detection, subsequent test methods directly measure the properties of the samples.

[0049] The difference between Examples 2 to 12 and Example 1 is that the phenyl-substituted acrylic monomers are A2 to A12, respectively.

[0050] The difference between Examples 13 to 17 and Example 1 is that the phenyl-substituted acrylic monomers are B1 to B5, respectively.

[0051] The difference between Examples 18 to 23 and Example 1 is that the phenyl-substituted acrylic monomers are C1 to C6, respectively.

[0052] In Examples 24 to 42, based on Example 3, the amounts of the components were adjusted, as shown in Table 4.

[0053]

[0054] Examples 42 to 44, based on Example 40, use silicone rubbers of different viscosities, as shown in Table 5.

[0055]

[0056] For the above examples, the following method was used for measurement.

[0057] 1. Wear resistance: Refer to GB / T9867.2008 "Determination of wear resistance of vulcanized rubber or thermoplastic rubber (rotating roller abrader method)" standard test.

[0058] 2. Hardness test: Determine the rubber hardness with reference to GB / T 531.1-2008 "Rubber pocket hardness test method for indentation hardness".

[0059] 3. Mechanical properties: The test was conducted in accordance with GB / T 528.2009 “Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties”. The three parameters of tensile strength, elongation at break, and permanent set at break were measured. The specimen shape was a Type 1 dumbbell-shaped specimen, and the tensile speed was 500 mm / min.

[0060] 4. Heat resistance test: Refer to GB / T 3512-2014 "Hot air accelerated aging and heat resistance test for vulcanized rubber or thermoplastic rubber" standard test, and measure the change rate of tensile strength after 96h, 168h, and 240h at a temperature of 200°C.

[0061] First, Experiments 1 to 3 were conducted on all examples, and the results are shown in Table 6.

[0062]

[0063] In the above examples, the plastic samples prepared in most examples can meet the basic mechanical requirements of conveyor belts, and some samples can achieve good mechanical properties for conveyor belts. Specifically, regarding the ratio of styrene, butadiene, and phenyl-substituted acrylic monomer block copolymer, it can be seen that when the molar ratio of the three monomers is within the range of 100:50-80:10-30, the overall mechanical properties are better. When the butadiene content is too low, the overall toughness is insufficient and the elongation at break is significantly reduced. When the butadiene content is too high, the system strength is insufficient and it is easy to break, with a significant reduction in both tensile strength and elongation at break.

[0064] The content of phenyl-substituted acrylate monomers also has a certain impact on mechanical properties. Specifically, when its content is reduced, the viscosity-enhancing and toughening effects deteriorate, and the elasticity weakens, resulting in a significant decrease in elongation at break and a significant increase in permanent set at break. When its content is too high, it has a certain negative impact on wear resistance and tensile strength.

[0065] The coupling agent in the system can significantly improve the mechanical properties of the sample. The lack of coupling agent not only has a significant adverse effect on the heat resistance, but also significantly reduces its tensile strength and wear resistance.

[0066] Reducing the amount of styrene-butadiene-phenyl-substituted acrylic monomer block copolymer has little effect on mechanical properties, but excessive use can lead to insufficient toughness of the system, a significant decrease in elongation at break, and a significant increase in permanent set at break. Nitrile experiments have shown that the mass of the styrene-butadiene-phenyl-substituted acrylic monomer block copolymer, which has a minimal impact on mechanical properties and can maximize heat resistance, should be no more than 30% of that of the styrene-butadiene copolymer.

[0067] Regarding the amount of polyphosphazene used, it can be seen from Examples 38 to 41 that the addition of polyphosphazene has a certain effect on the cohesion of the system. Excessive use of polyphosphazene will cause the rubber to be loose and brittle as a whole, and its elasticity will be weakened while the tensile strength will be reduced. The mass of polyphosphazene used should not exceed 10% of the mass of the styrene-butadiene copolymer.

[0068] The viscosity of silicone rubber also has a certain influence on the mechanical properties in the system. Silicone rubber with too low viscosity will lead to poor cohesion and elasticity, and have a certain adverse effect on tensile strength, elongation at break and permanent set at break.

[0069] In addition, Experiment 4 was conducted on some of the above embodiments, and the results are shown in Table 7.

[0070]

[0071] In the data of Table 7, increases are positive and decreases are negative.

[0072] Generally speaking, the molar content of styrene in styrene-butadiene rubber is generally between 20% and 30%. This application incorporates a ternary copolymer system with a high styrene content into the system, and at the same time utilizes the viscosity-increasing and toughening effects of phenyl-substituted acrylic monomers, so that the system can significantly improve the heat resistance while meeting good mechanical properties.

[0073] In the aforementioned experiments, a system of styrene-butadiene-phenyl-substituted acrylic monomer block copolymers was first studied. It was found that when the substituted acrylic monomer was replaced with methyl acrylate or methyl methacrylate, its heat resistance was significantly reduced. Among the monomers selected, methyl cinnamate provided higher heat resistance than the other monomers, making it a superior choice.

[0074] Table 5 shows that the dosage of the styrene-butadiene-phenyl-substituted acrylic monomer block copolymer is too high, leading to decreased mechanical properties, while too low a dosage significantly weakens heat resistance. Generally, a dosage of no less than 20 wt% of the styrene-butadiene copolymer is appropriate. Furthermore, regarding the molecular weight of the terpolymer, a molecular weight below 100,000 significantly adversely affects overall heat resistance. This may be because short-chain molecules in the system struggle to maintain a complete cross-linked structure, resulting in a weak system cohesion that cannot protect the basic styrene-butadiene copolymer structure. Consequently, mechanical properties degrade significantly at high temperatures.

[0075] The absence of phenylsuccinic acid will lead to a significant decrease in the heat resistance of the system, and the degree of decrease is more obvious over a long period of time. The reason may be that the coupling effect of phenylsuccinic acid in the system has better weather resistance and stronger heat resistance.

[0076] The addition of polyphosphazene can significantly improve the heat resistance, and the effect is more obvious in a time dimension greater than 168h, and the heat resistance effect increases with the increase of the amount of polyphosphazene added.

[0077] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A heat-resistant conveyor belt, characterized in that: The raw materials include the following components by mass: 100 parts of styrene-butadiene block copolymer 20-30 parts of styrene-butadiene-phenyl substituted acrylic monomer block copolymer 10-20 parts carbon black 0.1-0.5 parts of phenylsuccinic acid; In the styrene-butadiene-phenyl substituted acrylic monomer block copolymer, the molar ratio of the three monomers of styrene, butadiene and phenyl substituted acrylic monomer is 100:50-80:10-30; The phenyl-substituted acrylic monomer is any number of methyl cinnamate, ethyl cinnamate, propyl cinnamate, and butyl cinnamate.

2. A heat-resistant conveyor belt according to claim 1, characterized in that: The phenyl-substituted acrylic monomer is methyl cinnamate.

3. A heat-resistant conveyor belt according to claim 1, characterized in that: The number average molecular weight of the styrene-butadiene-phenyl substituted acrylic monomer block copolymer is 100,000 to 500,000.

4. A heat-resistant conveyor belt according to claim 1, characterized in that: The raw materials also include 3 to 8 parts by mass of silicone rubber.

5. A heat-resistant conveyor belt according to claim 4, characterized in that: The viscosity of the silicone rubber is 100,000 to 1,000,000 cps.

6. The heat-resistant conveyor belt according to claim 1, characterized in that: The raw materials also include 0.5 to 3 parts by mass of a cationic surfactant.

7. The heat-resistant conveyor belt according to claim 1, characterized in that: The raw materials also include 0.05 to 0.1 parts by mass of a coupling agent.

8. The heat-resistant conveyor belt according to claim 1, characterized in that: The raw materials also include 1 to 10 parts by mass of polyphosphazene.

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