A method for improving the wear resistance of the surface of a rubber conveyor belt by using ultra-high molecular weight polyethylene powder

Abstract

The application discloses a method for improving the surface wear resistance of a rubber conveying belt by using ultra-high molecular weight polyethylene powder, and comprises the following steps: (1) preparing modified ultra-high molecular weight polyethylene powder; (2) obtaining a working surface cover rubber layer of an unvulcanized rubber conveying belt; (3) uniformly spreading the modified ultra-high molecular weight polyethylene powder on the surface of the working surface cover rubber layer of the unvulcanized rubber conveying belt; and (4) heat-pressing and vulcanizing the working surface cover rubber layer of the unvulcanized rubber conveying belt which is spread with the modified ultra-high molecular weight polyethylene powder, so that the modified ultra-high molecular weight polyethylene powder is fixed on the surface of the working surface cover rubber layer of the rubber conveying belt in the form of particles during the heat-pressing and vulcanizing process, a surface wear-resistant particle layer is formed, and the surface wear resistance of the rubber conveying belt is improved. The method has the advantages that the wear resistance is maintained, and the flexibility of the conveying belt and the process economy are both considered.

Description

Technical Field

[0001] This invention relates to the field of rubber product processing, and specifically to a method for improving the surface wear resistance of rubber conveyor belts using ultra-high molecular weight polyethylene powder. Background Technology

[0002] Rubber conveyor belts are widely used in industrial production, logistics transportation, and mining operations, primarily for the continuous transport of materials. During long-term transport of high-hardness, sharp, or highly abrasive materials, the rubber cover layer on the conveyor belt surface is prone to wear, leading to a shortened service life, increased maintenance costs, and reduced production efficiency. Therefore, improving the wear resistance of rubber conveyor belt surfaces is of great significance.

[0003] Currently, to improve the wear resistance of conveyor belt cover rubber layers, methods such as optimizing rubber formulations, introducing wear-resistant fillers, setting surface wear-resistant layers, or improving processing techniques are commonly used. However, these methods still have certain shortcomings. For example, formulation optimization may lead to increased costs, and the performance improvement is limited; while surface coatings or overlays are prone to cracking, peeling, or failure under long-term friction, impact, and repeated bending conditions.

[0004] Ultra-high molecular weight polyethylene (UHMWPE) possesses characteristics such as low coefficient of friction, excellent wear resistance, and good chemical stability, and has received widespread attention in the field of wear-resistant materials in recent years. Existing technologies have attempted to laminate UHMWPE films or fabrics onto the surface of rubber conveyor belts to improve their wear resistance. However, these continuous layered materials tend to form a continuous covering layer on the conveyor belt surface after hot pressing, which is prone to wrinkles, localized warping, or interfacial instability during repeated bending, thus adversely affecting the original flexibility, elasticity, and flexural properties of the rubber conveyor belt. Furthermore, UHMWPE itself has poor melt flowability, typically requiring specialized processes and equipment to produce films or sheets, making its processing difficult and relatively costly.

[0005] Therefore, how to reduce processing difficulty and cost, and improve the wear resistance of rubber conveyor belt surface using UHMWPE without significantly affecting the flexural performance of rubber conveyor belt, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] Compared to UHMWPE films or fabric layers, UHMWPE powder has the advantages of relatively simple processing technology and low material cost. Introducing UHMWPE powder into the surface of rubber conveyor belts in granular form is expected to improve surface wear resistance while better maintaining the elasticity and flexibility of the rubber material itself. However, UHMWPE powder has low surface energy and strong chemical inertness, resulting in limited interfacial bonding force with rubber materials. If untreated UHMWPE powder is directly sprinkled onto the rubber surface, its interaction with the rubber mainly relies on mechanical interlocking, and the UHMWPE powder is prone to detachment during use, thus affecting the wear resistance enhancement effect and service stability. Therefore, the technical problem to be solved by this invention is to provide a method for improving the surface wear resistance of rubber conveyor belts using ultra-high molecular weight polyethylene powder. The ultra-high molecular weight polyethylene powder used in this method is relatively simple to process and has low cost, and can improve the surface wear resistance of conveyor belts while reducing the adverse effects on the elasticity and flexibility of the rubber conveyor belts.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for improving the surface abrasion resistance of rubber conveyor belts using ultra-high molecular weight polyethylene powder includes the following steps: (1) Preparation of modified UHMWPE powder: Di-tert-butyl peroxide isopropylbenzene (BIBP) and crosslinking agent are dissolved in an organic solvent to form a modified solution. UHMWPE powder is then immersed in the modified solution to allow BIBP and crosslinking agent to come into full contact and be adsorbed onto their surface. Subsequently, the organic solvent is evaporated and removed to obtain modified UHMWPE powder. (2) Obtain the working surface cover layer of the unvulcanized rubber conveyor belt; (3) The modified UHMWPE powder is evenly spread on the surface of the unvulcanized rubber conveyor belt cover layer, and the spreading amount of the modified UHMWPE powder is 0.01-0.06 kg / m. 2 ; (4) The working surface cover layer of the unvulcanized rubber conveyor belt with modified UHMWPE powder is hot-pressed and vulcanized. The hot-pressing and vulcanizing process fixes the modified UHMWPE powder in the form of particles on the surface of the working surface cover layer of the rubber conveyor belt, forming a wear-resistant particle layer, thereby improving the wear resistance of the rubber conveyor belt surface.

[0008] In this invention, the UHMWPE powder is first pretreated and modified to improve its adhesion to the rubber surface and the interfacial bonding strength. The processing technology and the amount of modified UHMWPE powder added directly affect the wear resistance of the conveyor belt surface layer rubber and should be kept within a suitable range.

[0009] Preferably, the weight-average molecular weight of the UHMWPE powder is 1 million to 10 million, more preferably 3 million to 6 million, and even more preferably 4 million.

[0010] Preferably, the UHMWPE powder is spread at a rate of 0.06 kg / m³. 2 .

[0011] Preferably, the crosslinking agent is triallyl isocyanurate (TAIC) or zinc dimethacrylate (ZDMA); the organic solvent is toluene.

[0012] Preferably, in the modified solution, the mass ratio of di-tert-butyl peroxide isopropylbenzene to the crosslinking agent is 1:(1-3), more preferably 1:2; the mass ratio of di-tert-butyl peroxide isopropylbenzene to the organic solvent is 1:80-120, more preferably 1:95-105.

[0013] Preferably, the mass ratio of the UHMWPE powder to the di-tert-butylperoxyisopropylbenzene in the modified solution is 10-25:1, more preferably 15-20:1.

[0014] Preferably, the soaking conditions for the UHMWPE powder are: at 40-80 °C. o Soaking is carried out under C conditions, preferably 50-70°C. o C, more preferably 60 o C; Soaking time is 10-30 min. Using a heated soaking method facilitates full contact between BIBP and the crosslinking agent and UHMWPE powder, thereby shortening the pretreatment time.

[0015] The composition and preparation method of the working surface cover rubber layer of the unvulcanized rubber conveyor belt of the present invention can both adopt conventional composition and preparation methods. Preferably, the working surface cover rubber of the rubber conveyor belt adopts a sulfur vulcanization system. In some embodiments, the composition of the working surface cover rubber layer of the unvulcanized rubber conveyor belt includes unsaturated rubber, vulcanizing activator, antioxidant, protective wax, reinforcing agent, processing oil, anti-scorching agent, vulcanization accelerator, and sulfur. The sulfur activator is zinc oxide and stearic acid, the reinforcing agent is carbon black and silica, and the vulcanization accelerator is CBS and TBBS. In some embodiments, the preparation steps of the working surface cover rubber layer of the unvulcanized rubber conveyor belt are as follows: first, the unsaturated rubber raw rubber, vulcanizing activator, antioxidant, protective wax, reinforcing agent, and processing oil are mixed evenly in an internal mixer to obtain a masterbatch; then, the masterbatch, anti-scorching agent, vulcanization accelerator, and sulfur are mixed evenly in a two-roll mill, and sheeted to obtain the working surface cover rubber layer of the unvulcanized rubber conveyor belt.

[0016] In step (4) of this invention, the unvulcanized rubber conveyor belt working surface cover layer is generally first bonded to the other structural layers of the rubber conveyor belt before hot-press vulcanization. The structural layers of the rubber conveyor belt typically include a working surface cover layer, a belt core layer, and a non-working surface cover layer. In some embodiments, an intermediate adhesive layer is also provided between the belt core layer and the cover layer. The composition of the non-working surface cover layer can be the same as that of the working surface cover layer, or a different composition can be selected as needed. The belt core layer can be a fabric core (cotton / nylon / EP canvas layer) or a steel wire rope core. The belt core layer, non-working surface cover layer, intermediate adhesive layer, and their thicknesses can all be conventionally selected as needed.

[0017] Preferably, the hot-press vulcanization conditions are: vulcanization temperature 145-155°C. o C, vulcanization time 12-45 min, pressure 6-8 MPa.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention can effectively improve the wear resistance of the conveyor belt surface by constructing a wear-resistant particle layer of UHMWPE powder on the surface of the unvulcanized rubber conveyor belt.

[0019] (2) In this invention, UHMWPE powder is fixed on the surface of the conveyor belt in the form of discrete particles after hot pressing. Compared with continuous UHMWPE film or fabric layer, it is less likely to form obvious wrinkles or local instability during repeated bending. Therefore, it has less impact on the elasticity and flexural performance of the conveyor belt.

[0020] (3) In this invention, BIBP is preferably used to pretreat UHMWPE powder. The pretreated UHMWPE powder has a higher fixation strength in the rubber surface, which helps to reduce its tendency to fall off during use, thereby helping to exert its surface wear resistance enhancement effect.

[0021] (4) The present invention uses UHMWPE powder as the surface wear-resistant material. Compared with the UHMWPE film solution, the material is easier to obtain, the process is relatively simple, the cost is relatively low, and it is more suitable for engineering applications. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the wear-resistant particle layer formed by modified UHMWPE powder on the surface of a rubber conveyor belt. The black part is the working surface cover layer, and the blue part is the wear-resistant particle layer formed by UHMWPE powder.

[0023] Figure 2 These are the Akron abrasion test results for each sample in the examples and control examples.

[0024] Figure 3These are comparative photos of the appearance of the UHMWPE film sample with hot-pressed rubber surface in Comparative Example 2 and the UHMWPE powder sample with surface sprinkled in Example 2 before and after ten bends. The top a (before bending) and b (after bending) are the hot-pressed UHMWPE film sample, and the bottom c (before bending) and d (after bending) are the powder-sprinkled sample. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] The UHMWPE powder used in the embodiments and comparative examples of this invention was provided by Zhejiang Qianxilong Fiber Special Fiber Co., Ltd., with a weight-average molecular weight of 4 million and a particle size of 80-120 μm.

[0027] Example 1

[0028] First, modified UHMWPE powder was prepared. 0.15 g of BIBP peroxide and 0.30 g of TAIC co-crosslinking agent were weighed and added to 14.85 g of toluene. The mixture was stirred until fully dissolved to obtain a modified solution, wherein the mass ratio of BIBP to TAIC was 1:2 and the mass ratio of BIBP to toluene was 1:99. Subsequently, 2.85 g of ultra-high molecular weight polyethylene (UHMWPE) powder was added to the above modified solution, and the mixture was stirred at 60 °C. o Stirring and soaking for 15 minutes under C conditions allows BIBP and TAIC to adhere to the surface and interior of the UHMWPE powder. The mixture is then placed in a fume hood to evaporate and remove toluene, resulting in modified UHMWPE powder that is fully in contact with and adsorbed onto the surface, ready for use. BIBP is an odorless peroxide; compared to DCP, using BIBP helps reduce odor problems caused by peroxide residues or decomposition byproducts in the product.

[0029] Samples were taken according to the formulation table shown in Table 1, and the masterbatch was prepared in an internal mixer (Lina, LN-G5L) with the mixer temperature set to 80°C. o C. Rotor speed 60 rpm, fill factor 0.7. First, natural rubber (NR), butadiene rubber (BR), and styrene-butadiene rubber (SBR) are added and plasticized for 2-3 minutes. Then, zinc oxide, stearic acid (SA), antioxidant 4020, antioxidant RD, and protective wax are added sequentially, and mixing continues for 4-5 minutes. Finally, carbon black N330, silica (SiO2), and aromatic oil are added, and after mixing for 2 minutes, the mixture is discharged. The discharge temperature is controlled at 90°C. o C.

[0030] Accelerators and vulcanization systems were added to the above masterbatch on a two-roll mill: the front and rear roll temperatures were set to 60 / 55 degrees Celsius. o C. The front and rear roller speeds are 12 / 10 rpm. On a two-roll mill, 100 g of masterbatch is first milled for approximately 5 minutes to allow it to wrap around the rollers. Then, according to the formulation in Table 1, scorch inhibitor CTP, accelerator CBS, accelerator TBBS, and sulfur S are added sequentially, and milling continues for 7-10 minutes. The milling is performed alternately, with alternating left and right cuts and cross-rolling, for a total of 5 thin passes and 7 triangular wraps to ensure uniform mixing of the additives. After stabilizing at a 0.8 mm roller gap for 1 minute, the mixture is sheeted. CTP, CBS, TBBS, and S are all commercially available industrial-grade products. The rubber matrix uses a conventional sulfur vulcanization system. In this embodiment, peroxide is used for the pretreatment of UHMWPE powder.

[0031] Modified UHMWPE powder was evenly spread on the surface of the film to be vulcanized using a 120-mesh sieve. The amount of modified UHMWPE powder spread was 0.03 kg / m². 2 Then it is placed in a flat vulcanizing machine for vulcanization, with the vulcanization temperature set to 155°C. o C, the vulcanization time was 15 min, and the pressure was 7 MPa. After the obtained vulcanized rubber sheet was placed at room temperature for 24 h, the abrasion resistance was tested according to the national standard GB / T 1689-2014 "Determination of abrasion resistance of vulcanized rubber (using Akron abrasion tester)". The results are shown in Table 2.

[0032] Table 1. Masterbatch Formulation Table

[0033] Example 2

[0034] Example 2 is basically the same as Example 1, except that the amount of modified UHMWPE powder spread on the film to be vulcanized is 0.06 kg / m². 2 The results are shown in Table 2.

[0035] Compare with Example 1

[0036] Same as Example 1, except that UHMWPE powder was not sprinkled on the film to be vulcanized. The results are shown in Table 2.

[0037] Compare with Example 2

[0038] Same as Example 1, except that a UHMWPE film is hot-pressed onto the film to be vulcanized, and the film mass is 0.096 kg / m. 2 The results are shown in Table 2.

[0039] Compare with Example 3

[0040] Same as Example 1, except that unmodified UHMWPE powder is evenly spread on the film to be vulcanized at a rate of 0.03 kg / m². 2 The results are shown in Table 2.

[0041] Compare with Example 4

[0042] Same as Example 2, except that unmodified UHMWPE powder is evenly spread on the film to be vulcanized at a rate of 0.06 kg / m². 2 The results are shown in Table 2.

[0043] Table 2. Akron abrasion test results for each sample

[0044] Note: The unit for wear volume is cm. 3 / 1.61 km.

[0045] As shown in Table 2, the wear volume of Control Example 1, which did not have UHMWPE powder applied, was 0.42 cm³. 3 / 1.61 km, indicating that the wear resistance of the base rubber itself is limited. Comparative Examples 3 and 4 respectively applied 0.03 kg / m² of abrasion-resistant material to the rubber surface. 2 and 0.06 kg / m 2 After processing with unmodified UHMWPE powder, the wear volume was reduced to 0.36 cm³. 3 / 1.61 km and 0.28 cm 3 / 1.61 km, indicating that the introduction of UHMWPE powder can improve the wear resistance of the rubber conveyor belt surface to a certain extent, and the wear resistance effect is further improved with the increase of powder amount. However, under the same powder amount conditions, after using modified UHMWPE powder in Examples 1 and 2, the wear volume was further reduced to 0.25 cm. 3 / 1.61 km and 0.18 cm 3 The wear resistance was 1.61 km, significantly lower than the corresponding unmodified UHMWPE powder sample. This indicates that the interfacial bonding between the UHMWPE powder and rubber was enhanced after modification, allowing it to be more firmly fixed to the rubber surface after vulcanization, thus playing a more effective role in wear resistance during the abrasion process.

[0046] Therefore, by introducing UHMWPE powder as a surface wear-resistant particle layer into the surface of the rubber conveyor belt and preferably using a pretreatment modification method to improve its fixation strength, the present invention can effectively improve the wear resistance of the rubber conveyor belt surface; at the same time, within the scope of the present invention, appropriately increasing the amount of UHMWPE powder spread can further improve the wear resistance effect.

[0047] Figure 3A comparison of the appearance of the hot-pressed UHMWPE film sample from Comparative Example 2 and the UHMWPE powder-coated sample from Example 2 after multiple bends is presented. It can be seen that the hot-pressed UHMWPE film sample is more prone to developing obvious creases after bending, while the appearance change of the UHMWPE powder-coated sample is relatively smaller. This indicates that compared to continuous film structures, the granular UHMWPE surface layer has less impact on the bending adaptability of the rubber substrate. It is evident that although the continuous UHMWPE film sample shown in Comparative Example 2 exhibits a lower value in Akron abrasion volume, combined with… Figure 3 As shown in the comparison of appearance after repeated bending, the continuous film structure is more prone to obvious creases under bending conditions; therefore, the advantage of the present invention is that while maintaining good wear resistance, it is more conducive to taking into account the flexibility adaptability of the conveyor belt and the process economy.

Claims

1. A method for improving the surface wear resistance of rubber conveyor belts using ultra-high molecular weight polyethylene powder, characterized in that: The method includes the following steps: (1) Preparation of modified ultra-high molecular weight polyethylene powder: Di-tert-butyl peroxide isopropylbenzene and crosslinking agent are dissolved in an organic solvent to form a modified solution, and then ultra-high molecular weight polyethylene powder is immersed in the modified solution so that the di-tert-butyl peroxide isopropylbenzene and crosslinking agent are fully contacted and adsorbed on its surface; then the organic solvent is evaporated and removed to obtain modified ultra-high molecular weight polyethylene powder; (2) Obtain the working surface cover layer of the unvulcanized rubber conveyor belt; (3) The modified ultra-high molecular weight polyethylene powder is evenly spread on the surface of the unvulcanized rubber conveyor belt cover layer, and the spreading amount of the modified ultra-high molecular weight polyethylene powder is 0.01-0.06 kg / m. 2 ; (4) The working surface cover layer of the unvulcanized rubber conveyor belt, which is covered with modified ultra-high molecular weight polyethylene powder, is subjected to hot-press vulcanization. The hot-press vulcanization process fixes the modified ultra-high molecular weight polyethylene powder in the form of particles on the surface of the working surface cover layer of the rubber conveyor belt, forming a wear-resistant particle layer, thereby improving the wear resistance of the rubber conveyor belt surface.

2. The method as described in claim 1, characterized in that: The weight-average molecular weight of the ultra-high molecular weight polyethylene powder is 1 million to 10 million.

3. The method as described in claim 2, characterized in that: The weight-average molecular weight of the ultra-high molecular weight polyethylene powder is 3 million to 6 million.

4. The method as described in claim 1, characterized in that: The application rate of the ultra-high molecular weight polyethylene powder is 0.06 kg / m³. 2 .

5. The method as described in claim 1, characterized in that: The weight-average molecular weight of the ultra-high molecular weight polyethylene powder is [value missing]. The crosslinking agent is triallyl isocyanurate or zinc dimethacrylate; the organic solvent is toluene.

6. The method as described in claim 1, characterized in that: In the modified solution, the mass ratio of di-tert-butyl peroxide isopropylbenzene to the crosslinking agent is 1:1-3; the mass ratio of di-tert-butyl peroxide isopropylbenzene to the organic solvent is 1:80-120.

7. The method as described in claim 1, characterized in that: The mass ratio of the ultra-high molecular weight polyethylene powder to the di-tert-butylperoxyisopropylbenzene in the modified solution is 10-25:

1.

8. The method as described in claim 1, characterized in that: The soaking conditions for the ultra-high molecular weight polyethylene powder are: at 40-80°C. o Soak under C conditions for 10-30 minutes.

9. The method as described in claim 1, characterized in that: The working surface cover of the rubber conveyor belt uses a sulfur vulcanization system.

10. The method as described in claim 1, characterized in that: The hot-press vulcanization conditions are: vulcanization temperature 145-155℃. o C, vulcanization time 12-45 min, pressure 6-8 MPa.

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