PVC (polyvinyl chloride) conveyor belt surface layer material with high wear resistance and preparation method of PVC conveyor belt surface layer material

Abstract

The invention relates to a PVC (polyvinyl chloride) conveyor belt surface layer material with high wear resistance and a preparation method thereof, and the surface layer material comprises the following components in parts by weight: 100 parts of PVC paste resin; 5 to 15 parts of SBR emulsion (based on solid content); 3 to 10 parts of BR emulsion (based on solid content); and 0.3 to 1 part of maleic anhydride grafted polyethylene. Through the synergistic effect of the SBR emulsion and the BR emulsion, the wear resistance and the dynamic friction coefficient of the surface layer material are improved, the material is endowed with good elasticity and buffering capacity, the running stability and the low-temperature flexibility of a conveying belt can be possibly improved, and the risk of low-temperature embrittlement is reduced. And the maleic anhydride grafted polyethylene compatilizer is used for improving interface bonding, so that the interface bonding force between the PVC matrix and the rubber dispersion phase is enhanced, a blending system is more stable, phase separation and interface stripping are not easy to occur, and a surface layer material can more effectively resist friction and abrasion of materials, so that the service life of the conveying belt is remarkably prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer composite materials and relates to a PVC conveyor belt surface material with high wear resistance and a preparation method thereof. Background Art

[0002] Polyvinyl chloride (PVC) conveyor belts are widely used in numerous industries, including mining, coal mining, ports, building materials, chemicals, and grain transportation, due to their relatively low cost, excellent chemical resistance, flame retardancy, and limited weather resistance. The conveyor belt's surface material (covering rubber) comes into direct contact with the conveyed material and is subject to various friction, wear, impact, and environmental factors during operation. Its performance directly determines the overall service life and operational reliability of the conveyor belt.

[0003] However, traditional PVC surface materials have high hardness but relatively low toughness, making them prone to brittle cracking, especially at low temperatures. More importantly, their wear resistance often fails to meet the demands of conveying materials over high-intensity, long distances, and in harsh working conditions. This leads to premature wear and failure of the conveyor belt surface, necessitating frequent replacement, increasing production costs and downtime for maintenance.

[0004] To improve the properties of PVC, existing technologies typically employ plasticizers to enhance its flexibility or blend it with other polymers. Incorporating rubber elastomers into PVC is a common method for enhancing its toughness and wear resistance. For example, styrene-butadiene rubber (SBR) offers excellent wear resistance and physical and mechanical properties, while butadiene rubber (BR) is known for its excellent elasticity and low-temperature resistance.

[0005] However, PVC is a highly polar polymer, while general-purpose rubbers such as SBR and BR are relatively weaker in polarity, resulting in poor thermodynamic compatibility between the two. Direct blending often results in severe phase separation and weak interfacial bonding, preventing the rubber phase from being uniformly dispersed in the PVC matrix in the desired size and morphology. This results in poor modification results and may even lead to a decrease in the material's mechanical properties.

[0006] In addition, therefore, the development of a PVC conveyor belt surface material that can significantly improve wear resistance while taking into account good elasticity and interface bonding strength, and has a reasonable preparation process, has important practical significance and economic value for extending the service life of the conveyor belt and reducing operating costs. Summary of the Invention

[0007] In response to at least one of the shortcomings mentioned in the background technology, the present invention aims to provide a PVC conveyor belt surface material with high wear resistance and a preparation method thereof, which has the characteristics of high wear resistance, can effectively extend the service life of the conveyor belt and improve its comprehensive performance.

[0008] The purpose of the present invention can be achieved through the following technical solutions: A highly wear-resistant PVC conveyor belt surface material, comprising, by weight: PVC paste resin: 100 parts; SBR emulsion (based on solid content): 5-15 parts; BR emulsion (based on solid content): 3-10 parts; Maleic anhydride grafted polyethylene: 0.3-1 part.

[0009] In this solution, PVC paste resin serves as the primary matrix material, providing the material's basic molding and processing properties, physical strength, chemical stability, and moderate wear resistance. SBR emulsion primarily contributes to wear resistance and dynamic friction performance, while BR emulsion aims to provide elastic cushioning, helping to absorb impact energy and reduce the cutting and ploughing effects of abrasives on the material surface. The two work synergistically to form a complementary microstructure, increasing the coefficient of friction and indirectly improving the material's wear resistance, thereby enhancing the grip of the PVC conveyor belt surface material and improving its performance under dynamic conditions. Maleic anhydride-grafted polyethylene (MAH-g-PE) acts as a compatibilizer, improving the interfacial bonding between the typically thermodynamically incompatible PVC and SBR and BR emulsions. This allows the rubber phase to be more finely and evenly dispersed in the PVC matrix, forming a more stable and less defective blend. This allows the SBR and BR emulsions to fully realize their technical capabilities and potentially delivers superior overall performance, particularly significant improvements in wear resistance, compared to simple physical mixing of the components or the absence of a compatibilizer.

[0010] Preferably, the SBR emulsion is used in an amount of 8-12 parts based on solid content; and the BR emulsion is used in an amount of 4-8 parts based on solid content.

[0011] Preferably, the content of styrene in the SBR emulsion is 20-30%.

[0012] Preferably, the solid content of the SBR emulsion is ≥55%, and the solid content of the BR emulsion is ≥50%.

[0013] Therefore, emulsions with high solid content have less residual water during solidification and are more likely to form a phase separation structure.

[0014] Preferably, the particle size of the SBR emulsion is 0.1-0.3 μm, and the particle size of the BR emulsion is 0.2-0.5 μm.

[0015] Therefore, the smaller particle sizes of SBR emulsion and BR emulsion can enhance the packing density of emulsion particles and promote the formation of microstructure.

[0016] Preferably, the components of the surface layer material further include at least one of a filler, a solvent regulator, a plasticizer, a surfactant, a nucleating agent, and a stabilizer.

[0017] Preferably, the surface layer material further comprises 5-10 parts of filler.

[0018] The filler is at least one of calcium carbonate, silicon dioxide, carbon black, kaolin and talc.

[0019] Preferably, the filler is silica sand or calcium carbonate, and the particle size of the silica sand and calcium carbonate is 5-20 microns.

[0020] Therefore, the addition of fillers is beneficial to enhance the stability of the concave-convex structure through mechanical embedding effect.

[0021] Preferably, the components of the surface layer material further include 0.5-2 parts of a solvent regulator.

[0022] Preferably, the solvent regulator is a volatile hydrophilic solvent, preferably ethanol or acetone.

[0023] Therefore, the addition of solvent regulator is beneficial to promote phase separation of emulsion particles during solvent evaporation.

[0024] Preferably, the surface layer material further comprises 1-6 parts of a plasticizer, preferably at least one of dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl terephthalate (DOTP), and epoxidized soybean oil.

[0025] Preferably, the components of the surface layer material further include 0.3-1.4 parts of a nucleating agent.

[0026] Preferably, the nucleating agent is at least one of diatomaceous earth or nano-silicon dioxide, and the particle size of the diatomaceous earth or nano-silicon dioxide is 20-50 nm.

[0027] In this way, the role of the nucleating agent is to act as a nucleation point to induce the emulsion particles to preferentially aggregate in specific areas during the curing process, forming a controllable concave-convex structure.

[0028] Preferably, the components of the surface layer material further include 0.2-2 parts of a stabilizer.

[0029] Preferably, the stabilizer is a calcium-zinc composite stabilizer.

[0030] The method for preparing the above-mentioned PVC conveyor belt surface layer material comprises the following steps: Add PVC paste resin, SBR emulsion, BR emulsion and maleic anhydride grafted polyethylene into a mixer, stir at a temperature of 35-45°C and a rotation speed of 500-1500 rpm for 30-60 minutes to form a PVC surface layer paste.

[0031] A light conveyor belt comprises a fabric skeleton and a surface layer coated on the fabric skeleton, wherein the surface layer is formed by solidifying the above-mentioned PVC conveyor belt surface layer material.

[0032] Furthermore, the curing conditions are: first drying at 40-60° C. for 30-60 minutes, then heating to 100-120° C. and drying for 10-30 minutes.

[0033] The slow drying stage at 40-60°C facilitates gentle and thorough moisture volatilization, avoiding premature surface closure and residual solvent within the product due to rapid heating, thereby reducing the risk of defects such as bubbles and pinholes in the final product. Furthermore, the lower temperature and slower drying rate facilitate the orderly accumulation and initial fusion of the emulsion particles, as well as the sufficient migration, orientation, and possible physical and chemical interactions of the maleic anhydride-grafted polyethylene at the interface, laying the foundation for the formation of a well-defined interfacial layer. This stage also effectively reduces the accumulation of internal stress in the material during the curing process.

[0034] The high-temperature, fast-drying stage, 100-120°C, is designed to promote complete plasticization of the PVC paste resin and form a continuous matrix phase. For the rubber component, high temperatures help improve its physical network. If the formula contains a small amount of reactive groups or a trace amount of crosslinking aid is subsequently added, high temperatures may also promote a slight crosslinking reaction, further stabilizing the morphology and properties of the rubber phase. Furthermore, high temperatures ensure the ultimate stabilization of the compatibilizer's effect and maximize interfacial bonding strength.

[0035] This staged, temperature-zone curing strategy, different from the traditional single-stage high-temperature rapid curing, may have a positive and non-obvious impact on the material's microstructure (such as phase domain size, interface layer thickness and strength, crystallinity, etc.), and may be conducive to the formation of a more layered micro-concave-convex structure, thereby significantly improving its macroscopic performance, enhancing grip, and improving wear resistance.

[0036] The traditional PVC paste resin curing process mostly uses a one-step high-temperature plasticizing molding. Although the process is simple, it may affect the microstructure and macroscopic properties of the final product due to factors such as rapid heating, insufficient volatilization of the solvent inside the paste, and large internal stress. It is difficult to fully realize the potential of each component, especially when pursuing specific properties such as high wear resistance, its limitations are more prominent.

[0037] Furthermore, the surface layer material is applied to the surface of the fabric skeleton by scraping or rolling, with a coating thickness of 1-5 mm.

[0038] Beneficial effects of the present invention: The present invention utilizes the synergistic effects of SBR emulsion and BR emulsion. The SBR emulsion primarily improves the wear resistance and dynamic friction coefficient of the surface layer material to cope with wear during material conveying. The introduction of BR emulsion imparts good elasticity and cushioning capacity to the material, helping to absorb impacts and reduce damage to the belt surface caused by hard materials. It may also improve the smooth operation and flexibility of the conveyor belt at low temperatures, reducing the risk of low-temperature brittle cracking. Furthermore, with the aid of a maleic anhydride-grafted polyethylene compatibilizer, the interfacial bonding is improved, which enhances the interfacial bonding between the PVC matrix and the rubber dispersed phase, making the blending system more stable and less prone to phase separation and interfacial peeling. This allows the surface layer material to more effectively resist friction and wear of the material, thereby significantly extending the service life of the conveyor belt. DETAILED DESCRIPTION

[0039] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0040] Ingredients PVC paste resin: brand PSH-30, K value about 70-72, Shenyang Chemical Co., Ltd.

[0041] SBR emulsion: SBR-1502 emulsion, white homogeneous emulsion, solid content 45±1%, Shandong Xianyuan Chemical Technology Co., Ltd.

[0042] BR emulsion: BR-9000 emulsion, solid content 42±1%, Yanshan Petrochemical.

[0043] Maleic anhydride grafted polyethylene (MAH-g-PE): brand CMG9801, grafting rate 0.8-1.2%, Shanghai Dingfen Chemical Technology Co., Ltd.

[0044] Dioctyl phthalate (DOP): industrial grade, Chuangyi Chemical Co., Ltd.

[0045] Light calcium carbonate: average particle size 15 microns, Hebei Hezhen Industrial Co., Ltd.

[0046] Silica sand, average particle size 15 μm, Henan Zhuizhu New Materials Co., Ltd.

[0047] Calcium zinc composite stabilizer, brand CZ-208, Shandong Xieheng New Material Technology Co., Ltd.

[0048] Conveyor belt base material: EP200 polyester canvas, width 500mm, Zhejiang Hongbang Textile Co., Ltd.

[0049] Example 1 A highly wear-resistant PVC conveyor belt surface material, comprising, by weight: PVC paste resin: 100 parts; SBR emulsion (based on solid content): 10 parts, i.e. about 22.2 parts of emulsion; BR emulsion (based on solid content): 6 parts, i.e. about 14.3 parts of emulsion; Maleic anhydride grafted polyethylene: 0.6 parts.

[0050] A lightweight conveyor belt comprises a fabric skeleton and a surface layer coated on the fabric skeleton, wherein the surface layer is formed by curing the above-mentioned PVC conveyor belt surface layer material, and the fabric skeleton is EP200 polyester canvas. The preparation method thereof comprises the following steps: S1. Add PVC paste resin into a high-speed mixer, increase the speed to 1000 rpm, and then slowly add SBR emulsion, BR emulsion, and maleic anhydride grafted polyethylene in sequence, and stir for 45 minutes to obtain a uniform and stable surface paste.

[0051] S2. Use a scraper coating method to evenly apply the prepared surface paste on the surface of the EP200 polyester canvas substrate, and control the coating dry film thickness to be approximately 2.0 mm.

[0052] S3. Place the coated conveyor belt in a blast oven and first slowly dry it at 50°C for 45 minutes; then increase the oven temperature to 110°C and continue rapid drying and plasticizing for 25 minutes.

[0053] S4. Take out and cool naturally to room temperature to obtain a PVC conveyor belt surface layer sample.

[0054] Example 2 A highly wear-resistant PVC conveyor belt surface material, comprising, by weight: PVC paste resin: 100 parts; SBR emulsion (based on solid content): 15 parts, i.e. about 33.3 parts of emulsion; BR emulsion (based on solid content): 3 parts, i.e. about 7.1 parts of emulsion; Maleic anhydride grafted polyethylene: 0.8 parts; Solvent regulator: ethanol, 1.5 parts; Filler: silica sand, 8 parts; Nucleating agent: nano-silica, average particle size 30nm, 1 part.

[0055] A lightweight conveyor belt comprises a fabric skeleton and a surface layer coated on the fabric skeleton, wherein the surface layer is formed by curing the above-mentioned PVC conveyor belt surface layer material, and the fabric skeleton is EP200 polyester canvas. The preparation method thereof comprises the following steps: S1. Add PVC paste resin, solvent regulator and nucleating agent into a high-speed mixer and stir at 300 rpm for 10 minutes. Then increase the speed to 1000 rpm and slowly add SBR emulsion, BR emulsion, maleic anhydride grafted polyethylene and light calcium carbonate in sequence. Continue stirring for 45 minutes to obtain a uniform and stable surface paste.

[0056] S2. Use a scraper coating method to evenly apply the prepared surface paste on the surface of the EP200 polyester canvas substrate, and control the coating dry film thickness to be approximately 2.0 mm.

[0057] S3. Place the coated conveyor belt in a blast oven and first slowly dry it at 40°C for 60 minutes; then increase the oven temperature to 100°C and continue rapid drying and plasticizing for 30 minutes.

[0058] S4. Take out and cool naturally to room temperature to obtain a PVC conveyor belt surface layer sample.

[0059] Example 3 A highly wear-resistant PVC conveyor belt surface material, comprising, by weight: PVC paste resin: 100 parts; SBR emulsion (based on solid content): 5 parts, i.e. about 11.1 parts of emulsion; BR emulsion (based on solid content): 10 parts, i.e. about 23.8 parts of emulsion; Maleic anhydride grafted polyethylene: 0.4 parts; Plasticizer: DOP, 5 parts; Filler: light calcium carbonate, average particle size 1.5 microns, 8 parts; Thermal stabilizer: CZ-208, 0.3 parts.

[0060] A lightweight conveyor belt comprises a fabric skeleton and a surface layer coated on the fabric skeleton, wherein the surface layer is formed by curing the above-mentioned PVC conveyor belt surface layer material, and the fabric skeleton is EP200 polyester canvas. The preparation method thereof comprises the following steps: S1. Add PVC paste resin, DOP plasticizer and heat stabilizer into a high-speed mixer and stir at 300 rpm for 10 minutes. Then increase the speed to 1000 rpm and slowly add SBR emulsion, BR emulsion, maleic anhydride grafted polyethylene and light calcium carbonate in sequence. Continue stirring for 45 minutes to obtain a uniform and stable surface paste.

[0061] S2. Use a scraper coating method to evenly apply the prepared surface paste on the surface of the EP200 polyester canvas substrate, and control the coating dry film thickness to be approximately 2.0 mm.

[0062] S3. Place the coated conveyor belt in a blast oven and first slowly dry it at 60°C for 30 minutes; then increase the oven temperature to 120°C and continue rapid drying and plasticizing for 20 minutes.

[0063] S4. Take out and cool naturally to room temperature to obtain a PVC conveyor belt surface layer sample.

[0064] Comparative Example 1 The difference from Example 3 is that no SBR emulsion, BR emulsion, and maleic anhydride grafted polyethylene are added to the surface material formula of Comparative Example 1. The remaining components, preparation steps, and parameters are the same.

[0065] Comparative Example 2 The difference from Example 3 is that no BR emulsion is added to the surface material formula of Comparative Example 2. The remaining components, preparation steps and parameters are the same.

[0066] Comparative Example 3 The difference from Example 3 is that maleic anhydride grafted polyethylene is not added to the surface layer material formula of Comparative Example 3. The remaining components, preparation steps and parameters are the same.

[0067] Comparative Example 4 The difference from Example 3 is that in step S3 of Comparative Example 4, the curing process is: directly placing the coated conveyor belt in an oven at 110° C. for drying and plasticizing for 30 minutes without a low-temperature slow drying step.

[0068] The following performance tests were performed on Examples 1-3 and Comparative Examples 1-4 respectively: (1) Akron abrasion test: The test is conducted in accordance with GB / T1689-2014 "Determination of wear resistance of vulcanized rubber or thermoplastic rubber (rotating roller abrader method)". The sample size is a disc with a thickness of 12.5 mm and a diameter of 63.5 mm. The abrasion wheel speed is 76 r / min, the load is 26.7 N, the deflection angle is 15°, and the abrasion distance is 1.61 km (1 mile). Calculate the wear volume loss (cm 3 / 1.61km). The smaller the wear volume loss value, the better the wear resistance.

[0069] (2) Tensile strength and elongation at break test: The test was conducted in accordance with GB / T528-2009 “Vulcanized rubber or thermoplastic rubber - Determination of tensile stress-strain properties”. Dumbbell-type No. Ⅰ specimens were used, and the tensile speed was 500 mm / min.

[0070] (3) Hardness test: The test shall be conducted in accordance with GB / T531.1-2008 “Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 1: Shore durometer method (Shore hardness)”.

[0071] The test results are shown in Table 1.

[0072] Table 1 Wear resistance comparison: From the Akron abrasion data, it can be seen that the abrasion of Examples 1, 2, and 3 is significantly lower than that of all the comparative examples. Specifically, from the abrasion data of Comparative Example 1 and Example 3, it can be seen that the introduction of SBR emulsion, BR emulsion, and MAH-g-PE has a significant effect on improving the wear resistance of the PVC surface layer; from the abrasion data of Comparative Example 4 and Example 3, it can be seen that the two-step curing process of low-temperature slow drying and high-temperature fast drying is superior to the traditional single-stage high-temperature curing process in preparing high-performance wear-resistant surface layers. The two-step curing process may form a more optimized material microstructure, which is conducive to the development of wear resistance.

[0073] Comparison of mechanical properties: The tensile strength and elongation at break of Examples 1, 2, and 3 are better than those of Comparative Examples 1, 2, 3, and 4, indicating that the formula and process of the present invention not only enhance the wear resistance, but also improve the overall mechanical properties of the material.

[0074] In summary, the PVC conveyor belt surface material formula and two-step curing preparation method proposed in the present invention can synergistically give play to the advantages of each component, effectively improve the compatibility of PVC and rubber, optimize the microstructure of the material, improve the wear resistance, and at the same time have good tensile properties and elongation at break.

[0075] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A PVC conveyor belt surface material with high wear resistance, characterized in that: Calculated by weight, it includes the following components: PVC paste resin: 100 parts; SBR emulsion (based on solid content): 5-15 parts; BR emulsion (based on solid content): 3-10 parts; Maleic anhydride grafted polyethylene: 0.3-1 part.

2. The PVC conveyor belt surface material with high wear resistance according to claim 1, characterized in that: The SBR emulsion is used in an amount of 8-12 parts based on solid content; the BR emulsion is used in an amount of 4-8 parts based on solid content.

3. The PVC conveyor belt surface material with high wear resistance according to claim 1, characterized in that: The particle size of the SBR emulsion is 0.1-0.3 microns, and the particle size of the BR emulsion is 0.2-0.5 microns; the solid content of the SBR emulsion is ≥55%, and the solid content of the BR emulsion is ≥50%.

4. The PVC conveyor belt surface material with high wear resistance according to claim 1, characterized in that: The components of the surface layer material further include at least one of a filler, a solvent regulator, a plasticizer, a surfactant, a nucleating agent, and a stabilizer.

5. The PVC conveyor belt surface material with high wear resistance according to claim 4, characterized in that: The weight proportion of the filler is 5-10 parts, the weight proportion of the solvent regulator is 0.5-2 parts, the weight proportion of the plasticizer is 1-6 parts, the weight proportion of the nucleating agent is 0.3-1.4 parts, and the weight proportion of the stabilizer is 0.2-2 parts.

6. The PVC conveyor belt surface material with high wear resistance according to claim 4, characterized in that: The filler is silica sand or calcium carbonate, and the particle size of the silica sand and calcium carbonate is 5-20 microns; the solvent regulator is a volatile hydrophilic solvent; the plasticizer is at least one of dioctyl phthalate, dibutyl phthalate, dioctyl terephthalate, and epoxy soybean oil; the nucleating agent is at least one of diatomaceous earth or nano-silica; and the stabilizer is a calcium-zinc composite stabilizer.

7. A method for preparing a highly wear-resistant PVC conveyor belt surface material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: adding PVC paste resin, SBR emulsion, BR emulsion and maleic anhydride grafted polyethylene into a mixer, stirring at a temperature of 35-45° C. and a rotation speed of 500-1500 rpm for 30-60 minutes to form a PVC surface layer paste.

8. A light conveyor belt comprising a fabric skeleton and a surface layer coated on the fabric skeleton, characterized in that: The surface layer is formed by solidifying the PVC conveyor belt surface layer material according to any one of claims 1 to 6.

9. The light conveyor belt according to claim 8, characterized in that: The curing conditions are: first drying at 40-60° C. for 30-60 minutes, then heating to 100-120° C. and drying for 10-30 minutes.

10. The light conveyor belt according to claim 8, characterized in that: The surface layer is coated on the surface of the fabric skeleton by scraping or rolling, and the coating thickness is 1-5 mm.

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