A high wear-resistant protective sleeve and its preparation method and its application in inter-rack rubber hose

Abstract

The present invention relates to a high wear-resistant protective sleeve and a preparation method thereof and an application of the high wear-resistant protective sleeve in a rack-to-rack rubber hose. The raw materials for the high wear-resistant protective sleeve include the following components in parts by weight: 50-65 parts of NBR, 20-30 parts of PVC, 10-30 parts of SBR, 1-4 parts of modified polytetrafluoroethylene, 10-20 parts of modified phenolic resin, 2-4 parts of zinc oxide, 3-6 parts of magnesium oxide, 1-2 parts of accelerator, 2-3 parts of sulfur, and 2-4 parts of antioxidant. The high wear-resistant protective sleeve has good flexibility and elasticity, can absorb shock and vibration, can protect the rubber hose from external physical damage, such as friction, scratches or impacts, and also has good impact resistance, and plays an obvious protective role on the steel wire in the rubber hose.

Description

Technical Field

[0001] The invention relates to the technical field of inter-rack rubber hoses, and in particular to a high-wear-resistant protective sleeve and a preparation method thereof and application thereof in inter-rack hose hoses. Background Art

[0002] Inter-frame hoses are an important part of the hydraulic support system. They connect various hydraulic supports and transmit pressure oil to achieve functions such as lifting, supporting and moving the supports. Due to the particularity of their working environment, inter-frame hoses are often exposed to the risks of wear, corrosion and damage, which not only affect the stability and reliability of the hydraulic system, but may also lead to safety accidents.

[0003] There are two main reasons for the damage of the inter-rack hose:

[0004] 1. Damage to the outer rubber layer: Due to frequent pushing, scraping, friction and collision, the outer rubber layer may be damaged, resulting in exposed steel wires, which will then rust, reduce the pressure bearing capacity, and eventually the pipe body may burst. 2. Excessive bending: The hose is also prone to bursting or joints being pulled out when it is excessively bent, which not only affects production progress, but may also cause safety accidents.

[0005] To reduce these risks, the measures currently taken include: 1. Installing a rubber sheath: This is a common protective measure, but its disadvantage is that it is not resistant to collision, and once the sheath is damaged, impurities can easily enter between the sheath and the hose, accelerating wear. 2. Installing a spiral sheath: This type of sheath is easily stretched and deformed during friction, and the protective effect is poor. Once damaged, the entire sheath needs to be replaced, which is difficult to operate, time-consuming and labor-intensive. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a high wear-resistant protective sleeve with excellent wear resistance and a preparation method thereof and an application of the high wear-resistant protective sleeve in inter-rack rubber hoses.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a highly wear-resistant protective sleeve, the raw materials for preparing the highly wear-resistant protective sleeve include the following components in parts by weight:

[0009] NBR 50-65 parts, PVC 20-30 parts, SBR 10-30 parts, modified polytetrafluoroethylene 1-4 parts, modified phenolic resin 10-20 parts, zinc oxide 2-4 parts, magnesium oxide 3-6 parts, accelerator 1-2 parts, sulfur 2-3 parts, antioxidant 2-4 parts;

[0010] The raw materials for preparing the modified phenolic resin include the following components in parts by weight: 55 parts of phenol, 6-12 parts of sodium silicate, 20-25 parts of formaldehyde and 2-3 parts of sodium hydroxide; the modified polytetrafluoroethylene includes the following raw materials in parts by weight: 1-5 parts of tung oil, 1-5 parts of carnauba wax, 40-50 parts of ethyl acetate and 3-8 parts of polytetrafluoroethylene;

[0011] The preparation method of the high wear-resistant protective sleeve comprises the following steps: mixing the raw materials at 92-105° C. and tableting to obtain the high wear-resistant protective sleeve.

[0012] The raw material polytetrafluoroethylene (PTFE) in the preparation of the high wear-resistant protective sleeve has a very low friction coefficient. Adding it to rubber can significantly reduce the friction and wear between the rubber and other surfaces and improve the wear resistance. Moreover, by introducing tung oil and carnauba wax on the surface of PTFE, the compatibility between PTFE and rubber NBR, SBR and PVC matrices can be improved, and the surface activity of PTFE can be increased, so that it can form a strong interaction with rubber molecules and form effective stress transfer, thereby improving the wear resistance of the composite material. As a natural vegetable oil, tung oil can be used as a surfactant to help PTFE to be better dispersed in the rubber matrix, reduce agglomeration, improve the uniformity and wear resistance of the composite material, and also adjust the brittleness of carnauba wax. Carnauba wax has a high melting point and good glossiness, and can form a protective film on the surface of the composite material. This film can reduce friction and wear on the surface of the material, thereby improving wear resistance. The combined use of tung oil and carnauba wax produces a synergistic effect. The two act together on PTFE and rubber matrices to further improve the wear resistance and hydrophobicity of the composite material. Therefore, the addition of modified polytetrafluoroethylene can improve the tensile strength and hardness of the composite material. The enhancement of these mechanical properties helps to improve the material's ability to resist wear.

[0013] Modified phenolic resin is added to the raw materials for preparing the high wear-resistant protective cover. Since the curing temperature of phenolic resin is 140-180°C, and the thermal decomposition temperature of PVC and SBR is 100-140°C, pure phenolic resin cannot be cured at less than 140°C. Based on this, the present invention modifies the phenolic resin, and the presence of sodium silicate can increase the crosslinking density, thereby improving the bonding strength. In addition, sodium silicate can also reduce the curing temperature and reduce the curing activation energy, because the modified phenolic resin is modified by sodium silicate, and it reacts with the phenolic resin to generate new crosslinking points, and generates a silicon dioxide network with the phenolic resin, so that the curing temperature of the modified phenolic resin is significantly reduced, and the modified phenolic resin is promoted to be cured and crosslinked with the rubber matrix in the range of 92-105°C. The phenolic resin after curing and crosslinking can increase the tensile strength and wear resistance of the rubber, thereby improving its mechanical properties. Because the phenolic resin forms a three-dimensional crosslinked network structure during the curing process, this structure can increase the impact resistance and hardness of the rubber. Phenolic resin can also be used as a filler, filling the gaps in the rubber to increase the overall density of the material, thereby improving the mechanical properties.

[0014] Preferably, the method for preparing the modified polytetrafluoroethylene comprises the following steps:

[0015] Carnauba wax and tung oil are added to ethyl acetate, heated at 75-85° C. until the carnauba wax and tung oil are completely dissolved, and then polytetrafluoroethylene is added, mixed evenly, and filtered to obtain modified polytetrafluoroethylene.

[0016] Preferably, the preparation method of the modified phenolic resin comprises the following steps: mixing phenol, sodium hydroxide, sodium silicate and water, heating at 75-85°C, then adding formaldehyde, performing intermittent polymerization, cooling, and performing dehydration treatment to obtain the modified phenolic resin. Water is used as a solvent to fully dissolve the raw materials, and then dehydration treatment will be performed, so the amount of water used can be adjusted according to actual conditions.

[0017] Sodium silicate is hydrolyzed to form silicon-oxygen bonds. Phenol and formaldehyde undergo intermittent polymerization under the condition of sodium hydroxide as a catalyst to form phenolic resin. The silicon-oxygen bonds in sodium silicate can react with phenolic resin to form a silicon dioxide network structure.

[0018] More preferably, the intermittent polymerization reaction time is 4-5 hours; and the dehydration treatment is evaporation under reduced pressure at 50-60°C.

[0019] Preferably, the mass ratio of NBR to modified polytetrafluoroethylene is (20-25):1. If the mass ratio is higher than this, that is, the amount of modified polytetrafluoroethylene added is too large, the rubber composite material will be hardened. Although the hardness can be improved, it will reduce flexibility and elasticity, and the surface of the high wear-resistant protective sleeve will be too rough, reducing the wear resistance. If the amount of modified polytetrafluoroethylene added is too low, the wear resistance of the high wear-resistant protective sleeve will be affected.

[0020] In a second aspect, the present invention provides a method for preparing the highly wear-resistant protective cover, comprising the following steps:

[0021] Add NBR, modified phenolic resin, zinc oxide, magnesium oxide, accelerator, antioxidant, and modified polytetrafluoroethylene to an open mill, wait for all the materials to be dispersed in the rubber, add sulfur, and then mix at 92-105°C to obtain a mixed rubber, then add SBR and PVC to the mixed rubber and continue to mix at 92-105°C for the second time, and after tableting, a high wear-resistant protective cover is obtained. The first mixing may not make all the compounding agents completely and evenly dispersed, so the second mixing can further improve the dispersibility of the compounding agents in the rubber matrix, thereby improving the performance of the final product.

[0022] More preferably, the secondary mixing time in the preparation method of the high wear-resistant protective cover is 100-120s and the pressure is 10-15MPa.

[0023] In a third aspect, the present invention provides the use of the highly wear-resistant protective sleeve in the preparation of inter-rack rubber hoses.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the high wear-resistant protective sleeve of the present invention, by introducing tung oil and carnauba wax on the surface of polytetrafluoroethylene, the compatibility between polytetrafluoroethylene and rubber NBR, SBR and PVC matrix can be improved, and the surface activity of polytetrafluoroethylene can be increased, so that it can form a strong interaction with rubber molecules and form effective stress transmission, thereby improving the wear resistance of the composite material. The modified phenolic resin is modified by sodium silicate, which reacts with the phenolic resin to generate new crosslinking points, which can significantly reduce the curing temperature of the phenolic resin and promote the curing and crosslinking of the modified phenolic resin with the rubber matrix within the range of 92 to 105°C. The phenolic resin after curing and crosslinking can increase the tensile strength and wear resistance of the rubber, thereby improving its mechanical properties. Therefore, the high wear-resistant protective sleeve of the present invention has good flexibility and elasticity, can absorb shock and vibration, and can protect the hose from external physical damage, such as friction, scratches or impacts. At the same time, it also has good impact resistance, which plays a significant protective role on the steel wire in the hose. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a differential scanning calorimetry curve diagram of the modified phenolic resin of Example 1, Examples 6 to 8 and Comparative Example 3. DETAILED DESCRIPTION

[0027] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0028] The sources of raw materials and equipment used in the following examples and comparative examples are as follows:

[0029] NBR: The manufacturer is Dongguan Nabaichuan Plastic Chemical Co., Ltd., the brand is powdered nitrile SH-P830F, and the nitrile content is 33%;

[0030] PVC: The manufacturer is Shanghai MacLean Biochemical Technology Co., Ltd., brand number is P766487;

[0031] SBR: The manufacturer is PetroChina Lanzhou Petrochemical Company, brand number is 1906;

[0032] Zinc oxide: The manufacturer is Wuhan Jiyesheng Chemical Co., Ltd.;

[0033] Magnesium oxide: Manufacturer: Wuhan Jiyesheng Chemical Co., Ltd.

[0034] Accelerator: N-tert-butyl-2-benzothiazole sulfenamide (NS), manufactured by Guangdong Wengjiang Chemical Reagent Co., Ltd.;

[0035] Sulfur: The manufacturer is Henan Kailun Chemical Co., Ltd., brand name IS HS 7020;

[0036] Antiaging agent: The manufacturer is Zhejiang Huangyan Zhedong Rubber Additive Co., Ltd., the brand is 4020NA;

[0037] Phenol: The manufacturer is Shanghai MacLean Biochemical Technology Co., Ltd., the brand is P815401, the purity is reagent grade 99%;

[0038] Sodium silicate: The manufacturer is Shanghai MacLean Biochemical Technology Co., Ltd., the brand is S822245, the purity is reagent grade;

[0039] Formaldehyde solution: manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd., brand F111936, purity ACS37wt.% aqueous solution, containing 10-15% methanol stabilizer by volume concentration (it should be noted that the formaldehyde added in the following examples and comparative examples is actually formaldehyde itself, and the amount of formaldehyde solution added needs to be converted again);

[0040] Sodium hydroxide: the manufacturer is Shanghai MacLean Biochemical Technology Co., Ltd., brand number S817971, purity is ACS97%, flakes;

[0041] Tung oil: The manufacturer is Hubei Hongfuda Biotechnology Co., Ltd., with a purity of 99%;

[0042] Carnauba wax: The manufacturer is Wuhan Jiyesheng Chemical Co., Ltd., brand No. 3 flakes;

[0043] Polytetrafluoroethylene: The manufacturer is Shanghai Zhenda Fluoroplastic Co., Ltd., the brand is JF-G90;

[0044] Hardness tester: Manufacturer: German Montek Company, brand: HT 3000;

[0045] Electronic tensile testing machine: the manufacturer is High Speed ​​Rail Testing Instrument Co., Ltd., the brand is AT-7000M;

[0046] Rebound tester: manufacturer is Jinan Hengpin Electromechanical Technology Co., Ltd., brand name is HP-WTB02;

[0047] Akron abrasion testing machine: The manufacturer is Guilin Ruite Testing Machine Co., Ltd., and the brand is WML-76.

[0048] Unless otherwise specified, other materials, reagents, etc. used in the examples and comparative examples can be obtained from commercial sources.

[0049] Example 1

[0050] A highly wear-resistant protective sleeve, the raw materials for its preparation include the following components in parts by weight:

[0051] 60 parts of NBR, 23 parts of PVC, 27 parts of SBR, 2.4 parts of modified polytetrafluoroethylene, 15 parts of modified phenolic resin, 3 parts of zinc oxide, 5 parts of magnesium oxide, 1 part of accelerator, 2 parts of sulfur, 4 parts of antioxidant; the mass ratio of NBR to modified polytetrafluoroethylene is 25:1.

[0052] The raw materials for preparing the modified phenolic resin include the following components in parts by weight: 50 parts of phenol, 9 parts of sodium silicate, 21 parts of formaldehyde and 2 parts of sodium hydroxide;

[0053] The preparation method of the modified phenolic resin comprises the following steps: mixing phenol, sodium hydroxide, sodium silicate and 100 mL of deionized water, heating at 80° C., then adding formaldehyde, performing intermittent polymerization for 4 hours, cooling, and performing dehydration treatment by reduced pressure evaporation at 55° C. to obtain the modified phenolic resin.

[0054] The modified polytetrafluoroethylene comprises the following raw materials in parts by weight: 3 parts of tung oil, 4 parts of carnauba wax, 45 parts of ethyl acetate, and 7 parts of polytetrafluoroethylene;

[0055] The preparation method of modified polytetrafluoroethylene comprises the following steps: adding carnauba wax and tung oil into ethyl acetate, heating at 80°C until the carnauba wax and tung oil are completely dissolved, then adding polytetrafluoroethylene, mixing evenly, filtering, and obtaining modified polytetrafluoroethylene.

[0056] The method for preparing the highly wear-resistant protective cover comprises the following steps:

[0057] Add NBR, modified phenolic resin, zinc oxide, magnesium oxide, accelerator, antioxidant and polytetrafluoroethylene into an open mill, add sulfur after all the materials are dispersed in the rubber, and then mix at 105°C to obtain a rubber compound. Then add SBR and PVC and continue to mix the rubber compound for a second time at 105°C and a pressure of 12MPa for 120s. After tableting, a high wear-resistant protective cover is obtained.

[0058] Example 2

[0059] A highly wear-resistant protective sleeve, the raw materials for its preparation include the following components in parts by weight:

[0060] 50 parts of NBR, 20 parts of PVC, 10 parts of SBR, 1 part of modified polytetrafluoroethylene, 10 parts of modified phenolic resin, 2 parts of zinc oxide, 3 parts of magnesium oxide, 1 part of accelerator, 2 parts of sulfur, and 2 parts of antioxidant; the mass ratio of NBR to modified polytetrafluoroethylene is 50:1.

[0061] The raw materials for preparing the modified phenolic resin include the following components in parts by weight: 45 parts of phenol, 8 parts of sodium silicate, 20 parts of formaldehyde and 2 parts of sodium hydroxide;

[0062] The preparation method of the modified phenolic resin comprises the following steps: mixing phenol, sodium hydroxide, sodium silicate and 100 mL of deionized water, heating at 75° C., then adding formaldehyde, performing intermittent polymerization for 5 hours, cooling, and performing dehydration treatment by reduced pressure evaporation at 50° C. to obtain the modified phenolic resin.

[0063] The modified polytetrafluoroethylene comprises the following raw materials in parts by weight: 1 part of tung oil, 1 part of carnauba wax, 40 parts of ethyl acetate, and 3 parts of polytetrafluoroethylene;

[0064] The preparation method of modified polytetrafluoroethylene comprises the following steps: adding carnauba wax and tung oil into ethyl acetate, heating at 75°C until the carnauba wax and tung oil are completely dissolved, then adding polytetrafluoroethylene, mixing evenly, filtering, and obtaining modified polytetrafluoroethylene.

[0065] The method for preparing the highly wear-resistant protective cover comprises the following steps:

[0066] Add NBR, modified phenolic resin, zinc oxide, magnesium oxide, accelerator, antioxidant and polytetrafluoroethylene into an open mixing mill, add sulfur after all the materials are dispersed in the rubber, and then mix at 92°C to obtain a rubber compound. Then add SBR and PVC and continue to mix the rubber compound for a second time at 92°C and a pressure of 10 MPa for 120 seconds. After tableting, a high wear-resistant protective cover is obtained.

[0067] Example 3

[0068] A highly wear-resistant protective sleeve, the raw materials for its preparation include the following components in parts by weight:

[0069] 65 parts of NBR, 30 parts of PVC, 30 parts of SBR, 4 parts of modified polytetrafluoroethylene, 20 parts of modified phenolic resin, 4 parts of zinc oxide, 6 parts of magnesium oxide, 2 parts of accelerator, 3 parts of sulfur, and 4 parts of antioxidant; the mass ratio of NBR to modified polytetrafluoroethylene is 16.25:1.

[0070] The raw materials for preparing the modified phenolic resin include the following components in parts by weight: 55 parts of phenol, 10 parts of sodium silicate, 25 parts of formaldehyde and 3 parts of sodium hydroxide;

[0071] The preparation method of the modified phenolic resin comprises the following steps: mixing phenol, sodium hydroxide, sodium silicate and 100 mL of deionized water, heating at 85° C., then adding formaldehyde, performing intermittent polymerization for 4 hours, cooling, and performing dehydration treatment by reduced pressure evaporation at 60° C. to obtain the modified phenolic resin.

[0072] The modified polytetrafluoroethylene comprises the following raw materials in parts by weight: 5 parts of tung oil, 5 parts of carnauba wax, 50 parts of ethyl acetate, and 8 parts of polytetrafluoroethylene;

[0073] The preparation method of modified polytetrafluoroethylene comprises the following steps: adding carnauba wax and tung oil into ethyl acetate, heating at 85°C until the carnauba wax and tung oil are completely dissolved, then adding polytetrafluoroethylene, mixing evenly, filtering, and obtaining modified polytetrafluoroethylene.

[0074] The method for preparing the highly wear-resistant protective cover comprises the following steps:

[0075] Add NBR, modified phenolic resin, zinc oxide, magnesium oxide, accelerator, antioxidant and polytetrafluoroethylene into an open mill, add sulfur after all the materials are dispersed in the rubber, and then mix at 105°C to obtain a rubber compound. Then add SBR and PVC and continue to mix the rubber compound for a second time at 105°C and a pressure of 15 MPa for 100s. After tableting, a high wear-resistant protective cover is obtained.

[0076] Example 4

[0077] The difference between Example 4 and Example 1 is that there is only one mixing step in the preparation method of the high wear-resistant protective cover.

[0078] Example 5

[0079] The difference between Example 5 and Example 1 is that the amount of sodium silicate added to the raw materials for preparing the modified phenolic resin is 6 parts.

[0080] Example 6

[0081] The difference between Example 6 and Example 1 is that the amount of sodium silicate added in the raw materials for preparing the modified phenolic resin is 12 parts.

[0082] Example 7

[0083] The difference between Example 7 and Example 1 is that the amount of NBR added to the raw material of the high wear-resistant protective sleeve is 60 parts, and the amount of modified polytetrafluoroethylene is 3 parts. That is, the mass ratio of NBR to modified polytetrafluoroethylene is 20:1. Example 8

[0084] The difference between Example 8 and Example 1 is that the amount of NBR added to the raw material of the high wear-resistant protective sleeve is 60 parts, and the amount of modified polytetrafluoroethylene is 2 parts. The mass ratio of NBR to modified polytetrafluoroethylene is 30:1

[0085] Example 9

[0086] The difference between Example 9 and Example 1 is that the amount of NBR added to the raw material of the high wear-resistant protective sleeve is 60 parts, and the amount of modified polytetrafluoroethylene is 4 parts. The mass ratio of NBR to modified polytetrafluoroethylene is 15:1.

[0087] Comparative Example 1

[0088] The difference between Comparative Example 1 and Example 1 is that the high wear-resistant protective cover of Comparative Example 1 does not contain modified polytetrafluoroethylene.

[0089] Comparative Example 2

[0090] The difference between Comparative Example 2 and Example 1 is that the polytetrafluoroethylene in Comparative Example 2 is not modified.

[0091] Comparative Example 3

[0092] The difference between Comparative Example 3 and Example 1 is that no sodium silicate is added to the modified phenolic resin in Comparative Example 3.

[0093] Comparative Example 4

[0094] The difference between Comparative Example 4 and Example 1 is that the amount of sodium silicate added in the raw materials for preparing the modified phenolic resin is 5 parts.

[0095] Comparative Example 5

[0096] The difference between Comparative Example 5 and Example 1 is that the two mixing temperatures of the high wear-resistant protective cover of Comparative Example 5 are 90°C.

[0097] Comparative Example 6

[0098] The difference between Comparative Example 6 and Example 1 is that the two mixing temperatures of the high wear-resistant protective cover of Comparative Example 6 are 120°C.

[0099] Comparative Example 7

[0100] The difference between Comparative Example 7 and Example 1 is that the modified polytetrafluoroethylene of Comparative Example 7 includes the following raw materials in parts by weight: 7 parts of tung oil, 45 parts of ethyl acetate, and 7 parts of polytetrafluoroethylene.

[0101] Comparative Example 8

[0102] The difference between Comparative Example 8 and Example 1 is that the modified polytetrafluoroethylene of Comparative Example 8 includes the following raw materials in parts by weight: 7 parts of carnauba wax, 45 parts of ethyl acetate, and 7 parts of polytetrafluoroethylene.

[0103] Performance Testing

[0104] The modified phenolic resins of Example 1, Examples 5 to 7 and Comparative Examples 3 to 4 were tested by differential scanning calorimetry (DSC). The specific DSC curves are shown in Figure 1 .

[0105] like Figure 1 It can be seen that the DSC of the curing process of the modified phenolic resin of Example 1 and Examples 5 to 7 all show two energy peaks. The first peak at a relatively low temperature of about 55°C is the endothermic peak of the evaporation of volatile substances such as formaldehyde during the heating process. The second peak is the exothermic peak formed during the curing process of phenolic formaldehyde. The curing process includes the formation of methylene and methylene ether bridges. It is known that if sodium silicate is added, Si-O bonds and silica networks will be formed during the curing process. Therefore, the presence of Si-O bonds and silica networks next to the common methylene and methylene ether bridges will affect the curing behavior of phenol formaldehyde. Figure 1 The temperatures corresponding to the second peak in the embodiment 1, embodiment 6, embodiment 5, comparative example 4 and comparative example 3 are from low to high. The second peak curing temperature of comparative example 3 is 131°C, indicating that the curing temperature of the phenolic resin can be significantly reduced by adding sodium silicate in embodiments 1 and embodiments 5 to 6, so that it can be cross-linked with other raw materials in the high wear-resistant protective cover at 92 to 105°C to improve the hardness and impact resistance of the high wear-resistant protective cover.

[0106] The following tests were performed on the high wear-resistant protective sleeves of Examples 1 to 9 and Comparative Examples 1 to 8 respectively:

[0107] 1. Shore A hardness: Tested using a hardness tester in accordance with GB / T 531.1-2008. See Table 1 for specific data.

[0108] 2. Tensile stress-strain performance: electronic tensile testing machine was used to test according to GB / T 528-2009 standard. The specific data are shown in Table 1.

[0109] 3. Rebound value: tested with a rebound tester in accordance with GB / T 1681-2009 standard. See Table 1 for specific data.

[0110] 4. Compression permanent deformation: Tested in accordance with GB / T 7759.1-2015 standard, using type A specimen, test conditions are 100℃×70h, specific data see Table 1;

[0111] 5. Wear resistance: The test was carried out using an Akron abrasion tester in accordance with GB / T 1689-2014. See Table 1 for details.

[0112] Table 1 Data of each group of samples

[0113]

[0114]

[0115] As shown in Table 1, Example 1 is the best example. The high wear-resistant protective sleeve has good hardness, flexibility, elasticity, and tensile strength, can absorb shock and vibration, and can protect the hose from external physical damage. The compression permanent deformation is low, indicating that it has good impact resistance and plays a significant protective role on the steel wire in the hose. In addition, the Akron wear loss is low, indicating good wear resistance. Using it to prepare the inter-rack hose is conducive to improving the stability and reliability of the hydraulic system.

[0116] In the preparation method of Example 4, only one mixing was performed, and the performance of the product was reduced, which shows that the secondary mixing can improve the dispersibility of each raw material, thereby improving the product performance.

[0117] The purpose of Example 1, Example 5-6 and Comparative Examples 3-4 is to explore the effect of the amount of sodium silicate added on the product performance. In Comparative Example 3, no sodium silicate was added, resulting in no change in the original curing temperature of the phenolic resin. Figure 1It can be seen that the original curing temperature of the phenolic resin in Comparative Example 3 is 131°C, and the curing temperature of the modified phenolic resin in Comparative Example 4 is 126°C, which is significantly lower than the mixing temperature of the product, resulting in the phenolic resin being unable to crosslink with the rubber matrix during the mixing process, resulting in a significant reduction in product performance. The addition of 6 to 12 parts of sodium silicate to the modified phenolic resin can reduce the curing temperature of the modified phenolic resin to 92 to 105°C, which is consistent with the mixing temperature, so that the modified phenolic resin can be crosslinked and cured in the rubber matrix, thereby improving the mechanical properties and wear resistance of the product.

[0118] The purpose of Example 1 and Examples 7 to 9 is to explore the effect of the mass ratio of NBR and modified polytetrafluoroethylene on the performance. If the amount of modified polytetrafluoroethylene added in Example 9 is too large, it will cause the rubber composite material to harden. Although it can increase the hardness, it will reduce the flexibility and elasticity, and it will also cause the surface of the high wear-resistant protective sleeve to be too rough, reducing the wear resistance. If the amount of modified polytetrafluoroethylene added in Example 8 is too low, it will affect the wear resistance of its high wear-resistant protective sleeve. Therefore, limiting the mass ratio of NBR and modified polytetrafluoroethylene to (20 to 25): 1 can make the hose have good hardness, flexibility, elasticity and wear resistance.

[0119] Comparative Example 1 does not add modified polytetrafluoroethylene, and its wear resistance is significantly reduced. Comparative Example 2 adds unmodified polytetrafluoroethylene, and its performance is also reduced. This is because polytetrafluoroethylene (PTFE) has a very low friction coefficient. Adding it to rubber can significantly reduce the friction and wear between rubber and other surfaces, and improve wear resistance. The introduction of tung oil and carnauba wax on the surface of polytetrafluoroethylene can improve the compatibility between polytetrafluoroethylene and rubber NBR, SBR and PVC matrix, and can also increase the surface activity of polytetrafluoroethylene, so that it can form a strong interaction with rubber molecules and form effective stress transfer, thereby improving the wear resistance of the composite material. It can be seen from Comparative Examples 7 to 8 that the combined use of tung oil and carnauba wax produces a synergistic effect, and the two act together on polytetrafluoroethylene and rubber matrix to further enhance the wear resistance and hydrophobicity of the composite material. Therefore, the addition of modified polytetrafluoroethylene can improve the tensile strength and hardness of the composite material, and the enhancement of these mechanical properties helps to improve the material's ability to resist wear.

[0120] The purpose of Example 1, Comparative Examples 5 and 6 is to explore the effect of mixing temperature on product performance. Since the minimum curing temperature of the modified phenolic resin is 92°C, if the temperature is lower than this, the phenolic resin cannot be cured in the rubber matrix, so the mechanical strength and wear resistance of the product in Comparative Example 5 are significantly reduced. The temperature of Comparative Example 6 is 120°C, and the modified phenolic resin can be cured and cross-linked smoothly, but PVC will be thermally decomposed, thereby reducing the mechanical properties and wear resistance of the product.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A highly wear-resistant protective cover, characterized in that: The raw materials for its preparation include the following components in parts by weight: NBR 50-65 parts, PVC 20-30 parts, SBR 10-30 parts, modified polytetrafluoroethylene 1-4 parts, modified phenolic resin 10-20 parts, zinc oxide 2-4 parts, magnesium oxide 3-6 parts, accelerator 1-2 parts, sulfur 2-3 parts, antioxidant 2-4 parts; The raw materials for preparing the modified phenolic resin include the following components in parts by weight: 45-55 parts of phenol, 6-12 parts of sodium silicate, 20-25 parts of formaldehyde and 2-3 parts of sodium hydroxide; the modified polytetrafluoroethylene includes the following raw materials in parts by weight: 1-5 parts of tung oil, 1-5 parts of carnauba wax, 40-50 parts of ethyl acetate and 3-8 parts of polytetrafluoroethylene; the mass ratio of NBR to modified polytetrafluoroethylene is (20-25):1; The preparation method of the high wear-resistant protective sleeve comprises the following steps: mixing the raw materials at 92-105° C. and tableting to obtain the high wear-resistant protective sleeve.

2. The high wear-resistant protective cover according to claim 1, characterized in that: The added amount of the sodium silicate is 9-12 parts.

3. The high wear-resistant protective cover according to claim 1, characterized in that: The preparation method of the modified polytetrafluoroethylene comprises the following steps: Carnauba wax and tung oil are added to ethyl acetate, and heated until the carnauba wax and tung oil are completely dissolved. Then polytetrafluoroethylene is added, mixed evenly, and filtered to obtain modified polytetrafluoroethylene.

4. The high wear-resistant protective cover according to claim 3, characterized in that: The heating temperature in the preparation method of modified polytetrafluoroethylene is 70-80°C.

5. The high wear-resistant protective cover according to claim 1, characterized in that: The preparation method of the modified phenolic resin comprises the following steps: Phenol, sodium hydroxide, sodium silicate and water are mixed, heated at 75-85° C., then formaldehyde is added to carry out intermittent polymerization reaction, and after cooling, dehydration treatment is carried out to obtain the modified phenolic resin.

6. The high wear-resistant protective cover according to claim 5, characterized in that: The time of intermittent polymerization reaction is 4-5h; the dehydration treatment is evaporation under reduced pressure at 50~60℃.

7. The method for preparing the highly wear-resistant protective cover according to any one of claims 1 to 6, characterized in that: The preparation method of the highly wear-resistant protective cover comprises the following steps: Add NBR, modified phenolic resin, zinc oxide, magnesium oxide, accelerator, antioxidant and modified polytetrafluoroethylene into an open mixing mill, add sulfur after all the materials are dispersed in the rubber, and then mix at 92-105°C to obtain a rubber compound, then add SBR and PVC and continue to mix the rubber compound for a second time at 92-105°C, and after tableting, a high wear-resistant protective cover is obtained.

8. Use of the high wear-resistant protective sleeve according to any one of claims 1 to 6 in the preparation of inter-rack rubber hoses.

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