Wear-resistant POE elastomer and preparation method thereof

Abstract

The invention relates to the field of functional polymer materials, and particularly discloses a wear-resistant POE elastomer and a preparation method thereof.The wear-resistant POE elastomer is prepared from, by weight, 55-75 parts of double-grafted POE, 6-12 parts of cycloolefin polymer, 5-10 parts of surface-treated silicon carbide, 8-15 parts of wollastonite and 0.5-1 part of zinc stearate. According to the invention, the polar modification of the double-grafted POE, the rigidity enhancement of the cycloolefin polymer, the wear resistance optimization of the surface-treated silicon carbide and the mechanical reinforcement of the wollastonite are realized, so that the cost is balanced while the multi-component synergistic mechanical properties are realized.

Description

Technical Field

[0001] The present invention belongs to the field of functional polymer materials, and particularly relates to a wear-resistant POE elastomer and a preparation method thereof. Background Art

[0002] POE elastomer is a thermoplastic elastomer copolymerized from ethylene and α-olefin through a metallocene catalyst. Its molecular chain contains a crystalline region (resin phase) and an amorphous region (rubber phase). The crystalline region provides strength as physical cross-linking points, while the amorphous region endows high elasticity, achieving a balance between elasticity and strength. The comprehensive performance of POE far exceeds that of traditional elastomers (such as EPDM, EVA, SBS, etc.), specifically manifested as high elasticity, tear resistance, impact resistance in low-temperature environments, and excellent wear resistance.

[0003] Wear resistance refers to the ability of a material to resist surface damage under mechanical friction or wear, and is a core index to measure the durability and service life of a material, which is affected by key factors such as material hardness, strength, and toughness. Under the demand for high-wear-resistant POE materials in various industries, Patent CN117534932B provides a self-lubricating, high-wear-resistant POE masterbatch with sound absorption and its preparation method. Its raw materials include maleic anhydride-grafted modified POE, sulfonated molybdenum disulfide, hollow microspheres, halloysite nanotubes, dimethyl silicone oil, benzene derivative-type dispersants, and antioxidants. This application uses the weak interlayer binding force of molybdenum disulfide nanosheets to reduce and stabilize the friction coefficient to improve the anti-wear performance. Another example is Patent CN117534933B, a highly conductive self-lubricating, high-wear-resistant POE masterbatch and its preparation method, which uses the unique ultra-thin layer structure and excellent self-lubricating performance of graphene as a friction-reducing additive. On this basis, by introducing graphene nanosheets to enhance the intermolecular force, the mechanical properties and wear resistance of the masterbatch are further improved. Although the POE elastomers provided by the above inventions have excellent wear resistance, their costs are relatively high. To improve the adaptability of use, it is necessary to further reduce costs and ensure wear resistance. Summary of the Invention

[0004] In order to overcome the deficiencies of the above prior art, the present invention provides a wear-resistant POE elastomer. Through the polar modification of double-grafted POE, the rigidity enhancement of norbornene polymer, the wear resistance optimization of surface-treated silicon carbide, and the mechanical reinforcement of wollastonite, the wear-resistant POE elastomer balances the cost while achieving an increase in mechanical properties. Among them, double-grafted POE serves as an elastomer matrix, forming chemical bonds or physical cross-links with other components through polar groups, reducing interfacial stress concentration, and improving the toughness of the material. The high rigidity of norbornene polymer compensates for the soft characteristics of POE elastomer, enhances the overall hardness of the composite material, and improves the wear resistance.

[0005] To achieve the above object, the technical solution adopted by the present invention is: On the one hand, the present invention provides a wear-resistant POE elastomer, which contains the following raw materials by weight: 55-75 parts of double-grafted POE, 6-12 parts of cycloolefin polymer, 5-10 parts of surface-treated silicon carbide, 8-15 parts of wollastonite, and 0.5-1 part of zinc stearate.

[0006] This wear-resistant POE elastomer balances the cost while achieving multi-component synergistic enhancement of mechanical properties through the polar modification of double-grafted POE, the rigidity enhancement of cycloolefin polymer, the wear resistance optimization of surface-treated silicon carbide, and the mechanical reinforcement of wollastonite. Among them, double-grafted POE serves as the elastomer matrix, forming chemical bonds or physical cross-links with other components through polar groups, reducing interfacial stress concentration, and improving the toughness of the material; the high rigidity of cycloolefin polymer compensates for the soft characteristics of POE elastomer and enhances the overall hardness and anti-deformation ability of the composite material.

[0007] In some embodiments, the preparation steps of the double-grafted POE are as follows: uniformly mix the graft monomer, dicumyl peroxide, and POE, and melt-extrude at 150-190 °C to obtain double-grafted POE.

[0008] In some embodiments, the graft monomer includes 2-hydroxyethyl acrylate and maleic anhydride.

[0009] In some embodiments, the mass ratio of 2-hydroxyethyl acrylate to maleic anhydride is 1:(0.4-0.6).

[0010] In some embodiments, the mass ratio of the graft monomer to POE is (0.02-0.04):1.

[0011] The present invention improves the interaction between the polymer matrix and inorganic fillers by grafting POE with 2-hydroxyethyl acrylate and maleic anhydride. Firstly, the anhydride groups of maleic anhydride combine with inorganic fillers through hydrogen bonds or covalent bonds using strong polarity; secondly, the hydroxyl groups of 2-hydroxyethyl acrylate form a hydrogen bond network with the filler surface, and the ester groups enhance the interfacial binding through van der Waals forces; thirdly, the introduction of 2-hydroxyethyl acrylate compensates for the problem of excessive polarity that may be caused by single maleic anhydride grafting, forming a multi-level interfacial interaction and enhancing the interfacial binding strength; further, the strong interfacial binding enables the load to be efficiently transferred from the matrix to the hard filler, reducing the wear caused by interfacial peeling and improving the wear resistance.

[0012] In some embodiments, the preparation steps of the surface-treated silicon carbide are as follows: Triethylamine was added to polymaleic acid, and the pH was adjusted to 7.5 - 8.5. After mixing and stirring, silicon carbide powder was added. After stirring for 20 - 40 min, an anhydrous ethanol solution containing silane coupling agent was added. After stirring for 1 - 3 h, the precipitate was collected, washed, and dried to obtain surface-treated silicon carbide.

[0013] In some embodiments, the particle size of the silicon carbide powder is 6 - 14 μm.

[0014] In some embodiments, the mass ratio of the polymaleic acid, silicon carbide powder, and silane coupling agent is (1 - 5):(1 - 10):(1 - 2).

[0015] The high hardness of the silicon carbide powder can significantly improve the wear resistance of the composite material. However, there are often agglomeration problems during the melt extrusion process. Considering that there is an oxide layer mainly composed of silicon dioxide on its surface, in the present invention, negatively charged polymaleic acid is used to coat the silicon carbide powder after alkali treatment, and then a silane coupling agent is added, enabling the silane coupling agent to be enriched on the surface of the silicon carbide powder, increasing the effective collision between the silane coupling agent and the silicon carbide surface, improving the grafting rate of the silane coupling agent, and thus alleviating the problem of uneven dispersion of the silicon carbide material caused by the self-polymerization of the silane coupling agent during the melt extrusion process.

[0016] In some embodiments, the wollastonite is acicular wollastonite, and the aspect ratio is (10 - 20):1.

[0017] The present invention utilizes acicular wollastonite with a specific aspect ratio to increase the formation rate of the three-dimensional network structure, thereby improving the tensile strength and flexural modulus of the elastomer.

[0018] On the other hand, the present invention provides a method for preparing the above-mentioned wear-resistant POE elastomer, and the specific steps are as follows: Using a twin-screw extruder, double-grafted POE, cycloolefin polymer, surface-treated silicon carbide, wollastonite, and zinc stearate were melt-blended at 150 - 160 °C and 180 - 220 r / min, and the extruded product was the wear-resistant POE elastomer.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. Through the polar modification of double-grafted POE, the rigidity enhancement of cycloolefin polymer, the wear resistance optimization of surface-treated silicon carbide, and the mechanical reinforcement of wollastonite, the present invention enables the wear-resistant POE elastomer to balance the cost while achieving the enhancement of mechanical properties. Among them, double-grafted POE serves as the elastomer matrix, forming chemical bonds or physical crosslinks with other components through polar groups, reducing interfacial stress concentration, and improving the toughness of the material; the high rigidity of the cycloolefin polymer compensates for the soft characteristics of the POE elastomer, enhancing the overall hardness and anti-deformation ability of the composite material.

[0020] 2. The double-grafted POE uses 2-hydroxyethyl acrylate and maleic anhydride to enhance the interaction between the polymer matrix and the inorganic filler. Firstly, the anhydride groups of maleic anhydride are combined with the inorganic filler through hydrogen bonds or covalent bonds by strong polarity. Secondly, the hydroxyl groups of 2-hydroxyethyl acrylate form a hydrogen bond network with the filler surface, and the ester groups enhance the interfacial bonding through van der Waals forces. Thirdly, the introduction of 2-hydroxyethyl acrylate compensates for the problem of excessive polarity that may be caused by single maleic anhydride grafting, forming a multi-level interfacial interaction and enhancing the interfacial bonding strength. Further, the strong interfacial bonding enables the load to be efficiently transferred from the matrix to the hard filler, reducing the wear caused by interfacial peeling and improving the wear resistance.

[0021] 3. The present invention selects acicular wollastonite to increase the formation rate of the three-dimensional network structure, thereby improving the tensile strength and flexural modulus of the elastomer. At the same time, negatively charged polymaleic acid-coated silicon carbide powder after alkali treatment is used, and then a silane coupling agent is added to enrich the silane coupling agent on the surface of the silicon carbide powder, increasing the effective collision between the silane coupling agent and the silicon carbide surface, improving the grafting rate of the silane coupling agent, and thus alleviating the problem of uneven dispersion of the silicon carbide material caused by the self-polymerization of the silane coupling agent during the melt extrusion process. Detailed Embodiments

[0022] The present invention will be described below in conjunction with specific implementation embodiments. It should be noted that the following examples are examples of the present invention, only for illustrating the present invention, and not for limiting the present invention. Other combinations and various improvements within the concept of the present invention can be made without departing from the gist or scope of the present invention.

[0023] It is worth noting that the raw materials used in the following preparation examples and examples, unless otherwise specified, are from any commercially available manufacturer: The cycloolefin polymer model is E48R; The number average molecular weight of polymaleic acid is 750 ± 50; The particle size of the silicon carbide powder is 10 ± 2 μm; The wollastonite is acicular wollastonite, and the aspect ratio is 14 ± 4:1; The POE is ENGAGE™8480 polyolefin elastomer, the octene content is 20 wt%, and the Mw is 94500 g / mol.

[0024] Preparation Example 1 The preparation steps of the double-grafted POE-A are as follows: 4 g of 2-hydroxyethyl acrylate, 2 g of maleic anhydride, 0.3 g of diisopropylbenzene peroxide are mixed evenly with 200 g of POE, and melt extrusion is carried out at 180 °C to obtain the double-grafted POE-A.

[0025] Preparation Example 2 The preparation steps of grafted POE-B are different from those of Preparation Example 1 in that maleic anhydride is replaced by an equal amount of 2-hydroxyethyl acrylate.

[0026] Preparation Example 3 The preparation steps of grafted POE-C are different from those of Preparation Example 1 in that 2-hydroxyethyl acrylate is replaced by an equal amount of maleic anhydride.

[0027] Preparation Example 4 The preparation steps of surface-treated silicon carbide A are as follows: Triethylamine was added to 300 g of polymaleic acid, and the pH was adjusted to 8. After mixing and stirring, 1 kg of silicon carbide powder was added. After stirring for 30 min, 500 g of a 20 wt% KH550 anhydrous ethanol solution was added. After stirring for 2 h, the precipitate was collected, washed, and dried to obtain surface-treated silicon carbide A.

[0028] Preparation Example 5 The preparation steps of surface-treated silicon carbide B are as follows: 1 kg of silicon carbide powder and 500 g of a 20 wt% KH550 anhydrous ethanol solution were stirred for 2 h, and then the precipitate was collected, washed, and dried to obtain surface-treated silicon carbide B.

[0029] Example 1 A wear-resistant POE elastomer, by weight, comprises the following raw materials: 65 parts of double-grafted POE-A, 9 parts of cycloolefin polymer, 7 parts of surface-treated silicon carbide A, 12 parts of wollastonite, and 0.7 part of zinc stearate.

[0030] The preparation steps of the wear-resistant POE elastomer in this example are as follows: Using a twin-screw extruder, double-grafted POE-A, cycloolefin polymer, surface-treated silicon carbide A, wollastonite, and zinc stearate were melt-blended at 155 °C and 200 r / min, and extruded to obtain the wear-resistant POE elastomer.

[0031] Example 2 A wear-resistant POE elastomer, by weight, comprises the following raw materials: 55 parts of double-grafted POE-A, 6 parts of cycloolefin polymer, 5 parts of surface-treated silicon carbide A, 8 parts of wollastonite, and 0.5 part of zinc stearate.

[0032] The preparation steps of the wear-resistant POE elastomer in this example are as follows: The double-grafted POE-A, cycloolefin polymer, surface-treated silicon carbide A, wollastonite and zinc stearate are melt-blended using a twin-screw extruder at 150 °C and 220 r / min, and the extruded product is the wear-resistant POE elastomer.

[0033] Example 3 A wear-resistant POE elastomer, by weight, comprises the following raw materials: 75 parts of double-grafted POE-A, 12 parts of cycloolefin polymer, 10 parts of surface-treated silicon carbide A, 15 parts of wollastonite, and 1 part of zinc stearate.

[0034] The preparation steps of the wear-resistant POE elastomer in this example are as follows: The double-grafted POE-A, cycloolefin polymer, surface-treated silicon carbide A, wollastonite and zinc stearate are melt-blended using a twin-screw extruder at 160 °C and 180 r / min, and the extruded product is the wear-resistant POE elastomer.

[0035] Example 4 This example provides a wear-resistant POE elastomer and its preparation method. The specific implementation is the same as that of Example 1, except that: the double-grafted POE-A is replaced by an equal amount of grafted POE-B.

[0036] Example 5 This example provides a wear-resistant POE elastomer and its preparation method. The specific implementation is the same as that of Example 1, except that: the double-grafted POE-A is replaced by an equal amount of grafted POE-C.

[0037] Example 6 This example provides a wear-resistant POE elastomer and its preparation method. The specific implementation is the same as that of Example 1, except that: the surface-treated silicon carbide A is replaced by an equal amount of surface-treated silicon carbide B.

[0038] Comparative Example 1 This comparative example provides a wear-resistant POE elastomer and its preparation method. The specific implementation is the same as that of Example 1, except that: the double-grafted POE-A is replaced by an equal amount of POE.

[0039] Comparative Example 2 This comparative example provides a wear-resistant POE elastomer and its preparation method. The specific implementation is the same as that of Example 1, except that: the surface-treated silicon carbide A is replaced by an equal amount of silicon carbide.

[0040] Comparative Example 3 This comparative example provides a wear-resistant POE elastomer and its preparation method. The specific implementation is the same as that of Example 1, except that: the cycloolefin polymer is replaced by an equal amount of double-grafted POE-A.

[0041] Performance testing: 1. Friction and wear performance testing: The POE elastomers extruded from Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to friction and wear performance testing according to the GB / T3960-2016 standard. The size was 30mm×7mm×6mm, the load was 30kg, the transmission speed was 200r / min -1 and the stainless steel friction ring was φ40mm×φ16mm×φ10mm to obtain the friction coefficient and wear amount.

[0042] 2. Hardness testing: The POE elastomers extruded from Examples 1 to 6 and Comparative Examples 1 to 3 were pressed into sheets (1mm) at 200°C using a flat vulcanizer. The rectangular spline size was 0.1cm×1cm×3cm, and the hardness was tested using a Shore hardness tester.

[0043] The results are shown in Table 1.

[0044] Table 1 It can be seen from the data in Table 1 that the POE elastomers of Examples 1 to 3 have higher hardness, and at the same time have lower friction coefficients and wear amounts, indicating excellent friction resistance. Compared with Example 1, in Comparative Example 1, ungrafted POE was directly added, and the hardness change was small, but the friction resistance performance decreased significantly; further combining Examples 4 and 5, in which POE was grafted only with 2-hydroxyethyl acrylate and maleic anhydride respectively, the hardness change of the obtained elastomer was also small, but the wear resistance decreased. The possible reason is that the interfacial bonding between the single-grafted POE and the inorganic filler weakened.

[0045] Compared with Example 1, the silicon carbide in Comparative Example 2 was not treated, and the hardness change of the POE elastomer was not obvious, but the friction coefficient and wear amount increased greatly. The possible reason is that the silicon carbide was unevenly distributed; the silicon carbide used in Example 6 was directly treated with a silane coupling agent. Although it maintained a high hardness, it affected the wear resistance. The possible reason is that the silane coupling agent underwent self-polymerization during the melt extrusion process, resulting in uneven dispersion of the silicon carbide material.

[0046] Combining Example 1 and Comparative Example 3, it can be seen that the addition of the cycloolefin polymer can improve the overall hardness of the composite material, thereby improving the wear resistance.

[0047] The above-described embodiments and comparative examples do not impose any formal restrictions on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, may make some modifications or equivalents by using the above-disclosed technical content. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A wear-resistant POE elastomer, characterized in that, By weight, it contains the following raw materials: 55 - 75 parts of double-grafted POE, 6 - 12 parts of cycloolefin polymer, 5 - 10 parts of surface-treated silicon carbide, 8 - 15 parts of wollastonite, and 0.5 - 1 part of zinc stearate.

2. The wear-resistant POE elastomer according to claim 1, wherein The preparation steps of the double-grafted POE are as follows: Mix the grafting monomer, dicumyl peroxide and POE evenly, and melt-extrude at 150 - 190 °C to obtain the double-grafted POE.

3. The wear-resistant POE elastomer according to claim 2, wherein, The grafting monomer contains 2-hydroxyethyl acrylate and maleic anhydride.

4. The wear-resistant POE elastomer according to claim 3, characterized in that, The mass ratio of 2-hydroxyethyl acrylate to maleic anhydride is 1:(0.4 - 0.6).

5. The wear-resistant POE elastomer according to claim 2, wherein The mass ratio of the grafting monomer to POE is (0.02 - 0.04):

1.

6. The wear-resistant POE elastomer according to claim 1, wherein, The preparation steps of the surface-treated silicon carbide are as follows: Add triethylamine to polymaleic acid, adjust the pH to 7.5 - 8.5, mix and stir, then add silicon carbide powder. After stirring for 20 - 40 min, add an anhydrous ethanol solution containing silane coupling agent, stir for 1 - 3 h, collect the precipitate, wash and dry to obtain the surface-treated silicon carbide.

7. The wear-resistant POE elastomer according to claim 6, wherein The particle size of the silicon carbide powder is 6 - 14 μm.

8. The wear-resistant POE elastomer according to claim 6, characterized in that, The mass ratio of polymaleic acid, silicon carbide powder and silane coupling agent is (1 - 5):(1 - 10):(1 - 2).

9. The wear-resistant POE elastomer according to claim 1, wherein The wollastonite is acicular wollastonite with an aspect ratio of (10 - 20):

1.

10. A method for preparing the wear-resistant POE elastomer according to any one of claims 1-9, characterized in that, The specific steps are as follows: Use a twin-screw extruder to melt-blend the double-grafted POE, cycloolefin polymer, surface-treated silicon carbide, wollastonite and zinc stearate at 150 - 160 °C and 180 - 220 r / min, and extrude to obtain the wear-resistant POE elastomer.

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