Wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene and preparation method thereof

Abstract

The invention belongs to the technical field of materials, and particularly relates to wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene and a preparation method thereof. The ultra-high molecular weight polyethylene comprises the following components in 100 parts by mass: 60-80 parts of a polyethylene matrix, 18-35 parts of a reinforced composite material and 4-6 parts of a compound additive, wherein the reinforced composite material is composed of glass fibers, carbon fibers and maleic anhydride grafted polyethylene; the compound additive comprises a flame retardant, a lubricant and an antioxidant. The ultra-high molecular weight polyethylene has excellent mechanical properties and chemical stability, high tensile strength and good corrosion resistance and wear resistance, and can meet the repair requirements under complex working conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of materials, and particularly relates to a wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene and a preparation method thereof. BACKGROUND

[0002] Ultra-high molecular weight polyethylene (UHMWPE) generally refers to polyethylene (PE) with a relative molecular mass of more than 1.5 million. The relative molecular mass of common PE is generally only 20-30 million, the relative molecular mass of domestic UHMWPE can reach 400-500 million, and the relative molecular mass of UHMWPE produced in Germany is as high as 1000 million.

[0003] The extremely high relative molecular mass of UHMWPE endows it with extremely excellent performance: ① Excellent environmental stress cracking resistance, 200 times that of common high-density polyethylene (HDPE) and 5-10 times that of common plastics; ② Extremely strong wear resistance, ranking first among plastics, 5-7 times that of common plastics and 7-10 times that of steel pipes; ③ Extremely high impact resistance, the impact strength being the highest among existing plastics, and even at-70℃, the impact strength is still quite high; ④ Excellent self-lubricating property, equivalent to that of polytetrafluoroethylene (PTFE); ⑤ Good chemical stability, electrical insulation, fatigue resistance and weather resistance; ⑥ Non-toxic, non-water-absorbing, small in density, non-adhesive, anti-static, noise-absorbing, and easy to machine and color.

[0004] UHMWPE is an existing high-quality engineering plastic. The pipe made of UHMWPE has obvious advantages compared with other plastic pipes and metal pipes in many aspects.

[0005] Although UHMWPE has the above excellent performance, due to its extremely high relative molecular mass, the melt viscosity of UHMWPE is extremely high (up to 1×108 Pa·s), the flowability is extremely poor, and the critical shear rate is extremely low. During processing, melt fracture is extremely easy to occur, and it is very difficult to process by using conventional plastic forming equipment and process. In order to extrude UHMWPE pipe by using ordinary extrusion equipment, it is necessary to modify UHMWPE, that is, to improve the flowability of UHMWPE by various means, or to improve the forming equipment, or to adopt new forming and processing technology.

[0006] Chinese patents CN101134827 and CN1807062 use liquid crystal polymer to modify UHMWPE. Liquid crystal polymer has excellent mechanical properties, wear resistance and flowability. The compounding of liquid crystal polymer and UHMWPE can obviously improve the processability of UHMWPE and improve its mechanical properties and wear resistance. However, the processing temperature is as high as 250-300℃, and the energy consumption is high.

[0007] Chinese patent CN1428370 mixes 85-95% of ultra-high molecular weight polyethylene, 3-15% of polysiloxane and 0.2-2% of antioxidant, uniformly stirs, dries in a vacuum drying oven at 40-60℃ for 5-7 hours, and extrudes and granulates the dried raw materials. The blend has greatly improved flowability due to the addition of silicone as a modifier. The prepared UHMWPE pipe has excellent wear resistance, corrosion resistance and low temperature resistance. However, the patent granulates the special material, which has high cost. SUMMARY

[0008] The application develops a wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene, which is modified by adding suitable reinforcing materials to a polyethylene matrix to obtain an ultra-high molecular weight polyethylene with mechanical properties and corrosion resistance and wear resistance.

[0009] To achieve the above-mentioned purpose, the application can adopt the following technical solutions: The application provides a wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene, which comprises the following raw materials in 100 parts by mass: 60-80 parts of a polyethylene matrix, 18-35 parts of a reinforcing combination and 4-6 parts of a composite additive. The reinforcing combination is composed of glass fiber, carbon fiber and maleic anhydride grafted polyethylene. The composite additive comprises a flame retardant, a lubricant and an antioxidant.

[0010] Preferably, in the reinforcing combination, the mass ratio of glass fiber, carbon fiber and maleic anhydride grafted polyethylene is (10-20):(5-10):(3-5).

[0011] The mass ratio of the flame retardant, the lubricant and the antioxidant is 2:2:1.

[0012] Preferably, the flame retardant comprises decabromodiphenyl ether and antimony trioxide.

[0013] Preferably, the mass ratio of decabromodiphenyl ether and antimony trioxide is 1.3:0.7.

[0014] Preferably, the lubricant comprises PE wax and molybdenum disulfide.

[0015] Preferably, the mass ratio of the PE wax and the molybdenum disulfide is 3:2.

[0016] Preferably, the lubricant comprises antioxidant 1010.

[0017] Preferably, the polyethylene matrix is high-density polyethylene.

[0018] Still another aspect of the present application provides a method for preparing a wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene, specifically comprising the following steps: (1) The raw materials are mixed according to the above mass parts, and stirred uniformly to obtain a mixture; (2) The mixture is placed in an extruder, and after plasticizing into a viscous flow state under the action of high temperature and high pressure, it is extruded and drawn into a wire, and then cooled and granulated to obtain the ultra-high molecular weight polyethylene.

[0019] Preferably, in step (2), the cooling is performed by using cooling water, the flow rate of the cooling water ranges from 8 t / h to 12 t / h, and the temperature of the cooling water ranges from 0℃ to 10℃.

[0020] Preferably, in step (2), the extruder is a conical twin-screw extruder, the barrel temperature is 7 zones, and the barrel temperature is distributed from low to high as follows: zone 1, 160℃; zone 2, 165℃; zone 3, 170℃; zone 4, 175℃; zone 5, 180℃; zone 6, 185℃; and zone 6, 180℃; the melt pressure is 20-25 MPa; and the feeding speed is 8-10 r / min.

[0021] The present application has at least the following beneficial effects: (1) The ultra-high molecular weight polyethylene provided by the present application has excellent mechanical properties and chemical stability, high tensile strength, good corrosion resistance and wear resistance, and can meet the repair requirements under complex working conditions.

[0022] (2) The preparation method of the ultra-high molecular weight polyethylene provided by the present application is simple and easy to mass-produce.

[0023] (3) The ultra-high molecular weight polyethylene provided by the present application is simple and easy to mass-produce. DETAILED DESCRIPTION

[0024] The application will be described in further detail below with reference to the embodiments and examples. These embodiments and examples are only used to explain the application and not to limit the scope of the application. The purpose of providing these embodiments and examples is to make the disclosure of the application more thoroughly and comprehensively understood. It should also be understood that the application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or changes without departing from the spirit and scope of the application, and the equivalent forms obtained thereby also fall within the protection scope of the application. In addition, in the following description, a large number of specific details are given in order to provide a more complete understanding of the application. It should be understood that the application can be implemented without one or more of these details.

[0025] In some embodiments, the polyethylene matrix is 60-80 parts by mass. Illustratively, the polyethylene matrix can be used in an amount of 60 parts, 65 parts, 70 parts, 75 parts, 80 parts. Further, the polyethylene matrix is preferably 65-75 parts.

[0026] Polyethylene itself has excellent wear resistance, impact resistance, self-lubricating property and chemical stability. The application controls the amount of polyethylene matrix to be more than 60 parts by mass, which ensures that these inherent excellent properties dominate in the composite material. If the matrix content is too low (e.g. less than 60 parts), the material will be closer to a fiber or filler-based reinforced plastic, and the flexibility, high impact strength and excellent long-term environmental stress cracking resistance of the material itself will be severely weakened, and the material may become brittle and less tough.

[0027] At the same time, sufficient matrix content provides sufficient "wrapping" material for the reinforced compound, ensuring that the compatibilizer can fully play a bridging role to form a firm interfacial bond between the fiber and the matrix, avoiding the fiber from becoming a stress concentration point or being pulled out prematurely due to insufficient wetting or poor interfacial adhesion, thereby maximizing the reinforcement efficiency. Further, controlling the matrix content to be at least 60 parts is to ensure that the mixture still has a sufficient polymer continuous phase to provide a certain flowability after melting.

[0028] On the other hand, the upper limit is set at 80 parts, which means that at least 20 parts of other components (reinforcing material + additives) must be added. These additives, especially lubricants (such as PE wax, molybdenum disulfide) and low molecular weight maleic anhydride grafted polyethylene, act as "processing aids" in actual processing. They can effectively reduce the melt viscosity and reduce friction, making it possible to continuously produce at relatively mild temperatures (up to 185-188°C) using a conventional conical twin-screw extruder. If the matrix content exceeds 80 parts, the reinforcement and processing improvement effect will be insufficient.

[0029] The inventors creatively control the amount of polyethylene matrix to be 60-80 parts by mass, which firstly provides effective matrix support and interface bonding conditions for the reinforcing fibers on the basis of ensuring the performance advantages of high molecular weight polyethylene itself, maintains the processability of the material on conventional equipment, realizes the optimal design between high performance and controllable cost, and finally enables the prepared composite material to meet the comprehensive and severe requirements for strength, toughness, wear resistance and corrosion resistance under complex working conditions.

[0030] In some embodiments, the reinforcing compound is 18-35 parts by mass. Exemplarily, the amount of the reinforcing compound can be 18 parts, 20 parts, 25 parts, 30 parts, 35 parts. Further, the reinforcing compound is preferably 20-30 parts.

[0031] The inventors found that when the content of the reinforcing compound is less than 18 parts, its reinforcing effect on the polyethylene matrix (especially the improvement of tensile strength and modulus) will not be significant enough. 18 parts is the amount verified in the system of the present application to form an effective continuous or semi-continuous stress transfer network; a content higher than 18 parts by mass will result in extremely poor melt flowability, generating huge friction heat and back pressure during extrusion, exceeding the processing capacity of conventional twin-screw extruders, and easily leading to problems such as melt rupture, machine jamming, and excessive fiber shearing. Controlling the amount of reinforcing compound to be 18-35 parts ensures that the fiber reinforcing effect is fully exerted, while strictly avoiding the processing disasters and performance short boards caused by excessive filling. Through the synergy with 60-80 parts of polyethylene matrix and the assistance of composite additives, this design enables the present application to prepare a composite material that achieves the best balance between high strength, high toughness, ultra wear resistance, corrosion resistance and good processability.

[0032] In some embodiments, the reinforcing compound includes glass fiber, carbon fiber and maleic anhydride grafted polyethylene in a mass ratio of (10-20):(5-10):(3-5). Exemplarily, in the reinforcing compound, the mass ratio of glass fiber, carbon fiber and maleic anhydride grafted polyethylene can be 10:5:3, 15:5:3, 20:5:3, 10:10:3, 20:10:3, 15:5:3, 15:10:3, 2:1:1, 4:2:1.

[0033] Glass fiber as the main reinforcing framework, can significantly improve the elastic modulus, hardness and dimensional stability of the composite material, and effectively reduce the material cost; carbon fiber has higher specific strength and specific modulus, its addition can further improve the tensile strength, bending strength and creep resistance of the material; the molecular chain structure of MAH-g-PE is similar to that of UHMWPE matrix, which can intertwine and co-crystallize; and the anhydride groups grafted on the molecular chain can react with the active groups such as hydroxyl groups on the surface of glass fiber and carbon fiber or form strong hydrogen bonds. The amount of MAH-g-PE is the optimal amount for effective lubrication and dispersion of the total fiber amount, which ensures that the fibers can be uniformly distributed in the matrix under the extrusion process conditions described in the examples, avoiding local stress concentration, and thus obtaining a composite material with uniform performance.

[0034] In some embodiments, the compounding aid is 4-6 parts by mass. For example, the amount of the compounding aid can be 4 parts, 5 parts, or 6 parts.

[0035] In some embodiments, in the compounding aid, the mass ratio of the flame retardant, lubricant and antioxidant is (1.5-2.5):(1.5-2.5):1. For example, in the compounding aid, the mass ratio of the flame retardant, lubricant and antioxidant is 1.5:1.5:1, 2:1.5:1, 2.5:1.5:1, 2:2:1, 2.5:2.5:1, 2:2.5:1, 2.5:2:1. For example, the flame retardant includes decabromodiphenyl ether and antimony trioxide; the lubricant includes PE wax and molybdenum disulfide.

[0036] PE wax as an internal lubricant can effectively reduce the friction between UHMWPE molecular chains and improve the melt flowability; molybdenum disulfide as a solid lubricant can form a lubricating film between the fiber and the metal equipment surface, reducing frictional heat and screw wear. It is used to solve the processing flowability. If the lubrication is insufficient, the processing will not proceed smoothly, and the material performance cannot be guaranteed. The addition of the flame retardant gives the material the possibility of application in complex dangerous environments such as flammable and explosive environments. The antioxidant is used to make the material continuously resist the oxidation aging caused by heat, light and environmental stress during long-term use, and maintain the stability of the mechanical properties and corrosion resistance of the material.

[0037] Too much lubricant (far more than 2.5 parts) can cause the melt to be too slippery, make it difficult to feed, and the extrudate to be not dense, and even affect the mechanical strength and surface printing / bonding performance of the product; too much flame retardant can affect the melt flowability, reduce the surface finish of the product, and compete with the antioxidant for free radicals, which can interfere with long-term thermal stability. 1 part of antioxidant is the concentration verified to be effective for the system. Too little will not provide adequate protection; too much may migrate and precipitate, or interact with the flame retardant system unnecessarily.

[0038] Example 1: To provide an ultra-high molecular weight polyethylene According to 100 parts by mass, the polyethylene comprises: polyethylene matrix (molecular weight ~ 3 million) 70 parts; reinforcing compound 25 parts (glass fiber 12 parts, carbon fiber 8 parts, maleic anhydride grafted polyethylene 5 parts); composite additives 5 parts (flame retardant 2 parts, lubricant 2 parts, antioxidant 1010 1 part); wherein the flame retardant comprises decabromodiphenyl ether 1.3 parts and antimony trioxide 0.7 parts, the lubricant comprises PE wax 1.2 parts and molybdenum disulfide 0.8 parts.

[0039] Preparation method: After mixing the raw materials, melt blending is carried out by using a conical twin-screw extruder. The temperature partition of the barrel is set as: 160 / 165 / 170 / 175 / 180 / 185 / 180℃; the melt pressure is 22 MPa; the feeding speed is 9 r / min. The extruded strands are cooled by 5℃ cooling water (flow rate 10 t / h) and then cut into particles.

[0040] Performance: density 0.940 g / cm 3 ; tensile strength 45 MPa; elongation at break 350%; Taber abrasion amount 12 mg; mass change rate after soaking in 10% HCl solution for 30 days <0.5%.

[0041] Example 2: To provide an ultra-high molecular weight polyethylene The difference from Example 1 is that the polyethylene comprises: polyethylene matrix (molecular weight ~ 2.5 million) 65 parts; reinforcing compound 30 parts (glass fiber 15 parts, carbon fiber 10 parts, maleic anhydride grafted polyethylene 5 parts).

[0042] Preparation method: The difference from Example 1 is that the melt pressure is adjusted to 24 MPa and the cooling water temperature is 2℃.

[0043] Performance: density 0.943 g / cm 3 ; tensile strength 48 MPa; elongation at break 320%; Taber abrasion amount 9 mg; mass change rate after soaking in 10% NaOH solution for 30 days <0.3%.

[0044] Example 3: To provide an ultra-high molecular weight polyethylene According to 100 parts by mass, polyethylene matrix (molecular weight ~ 4 million) 80 parts; reinforcing compound 16 parts (glass fiber 8 parts, carbon fiber 5 parts, maleic anhydride grafted polyethylene 3 parts); composite additives 4 parts (flame retardant 1.6 parts, lubricant 1.6 parts [PE wax / molybdenum disulfide = 0.96 / 0.64], antioxidant 1010 0.8 parts); wherein the flame retardant comprises decabromodiphenyl ether 1.04 parts and antimony trioxide 0.56; the lubricant comprises 0.96 parts of PE wax and 0.64 parts of molybdenum disulfide.

[0045] Preparation: The difference from Example 1 is that the temperature of the cylinder is reduced by 5°C in total and the feeding speed is 10 r / min.

[0046] Performance: Density 0.937 g / cm 3 ; tensile strength 40 MPa; elongation at break 400%; Taber abrasion 15 mg; excellent corrosion resistance to 10% NaCl solution.

[0047] Example 4: To provide a kind of ultra-high molecular weight polyethylene According to 100 parts by mass, polyethylene matrix (molecular weight ~ 3.5 million) 72 parts; reinforcing compound 24 parts (glass fiber 14 parts, carbon fiber 6 parts, maleic anhydride grafted polyethylene 4 parts); composite auxiliary agent 4 parts (the same as in Example 1, reduced in proportion).

[0048] Preparation: The key is to adjust the reinforcing compound pre-dispersion treatment: glass fiber and carbon fiber are pre-mixed with a small amount of maleic anhydride grafted polyethylene at 80°C, and then blended with other raw materials. The extrusion process is the same as in Example 1.

[0049] Performance: Density 0.941 g / cm 3 ; tensile strength 47 MPa; Taber abrasion 11 mg. The pre-dispersion treatment of the fiber improves its distribution in the matrix, and the material performance is more uniform.

[0050] Example 5: To provide a kind of ultra-high molecular weight polyethylene The difference from Example 1 is that, according to 100 parts by mass, polyethylene matrix (molecular weight ~ 3.2 million) 68 parts; reinforcing compound 28 parts (glass fiber 10 parts, carbon fiber 12 parts, maleic anhydride grafted polyethylene 6 parts); composite auxiliary agent 4 parts (mass ratio of flame retardant, lubricant, antioxidant is 2.0:1.5:0.5); Preparation: In the extrusion process, the temperature of the 6th and 7th zones of the cylinder is increased to 188°C and 183°C to better melt the high content of carbon fiber.

[0051] Performance: Density 0.944 g / cm 3 ; tensile strength 50 MPa; conductivity is improved; wear resistance and corrosion resistance remain excellent. Higher proportion of carbon fiber provides higher strength and gives the material certain antistatic properties.

[0052] Comparative Example 1: Use commercially available ordinary high-density polyethylene (molecular weight about 0.5 million) pellets, without adding any reinforcing materials and composite auxiliary agents, under the same process conditions, extrusion granulation.

[0053] Performance: tensile strength 22 MPa; Taber abrasion 65 mg; obvious swelling and embrittlement on the surface after 30 days of immersion in 10% HCl solution, mass change rate > 3.0%.

[0054] The above examples 1-5 show that by adjusting the polyethylene matrix molecular weight, the proportion and composition of the reinforcing compound, and the ratio of the composite additives, and combining with the corresponding process optimization, a series of high-performance materials with different balances between mechanical strength, wear resistance and chemical corrosion resistance can be obtained, and the comprehensive performance is far superior to ordinary polyethylene in the comparative examples. The material of the present application is particularly suitable for non-excavation pipeline repair and other fields with strict requirements on strength, durability and environmental resistance. The preparation method is stable and easy to realize large-scale production.

[0055] The technical features of the above-described examples can be combined in any way. In order to make the description simple, all possible combinations of the technical features in the above examples are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0056] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene, characterized in that, By weight, it includes the following raw materials: 60-80 parts of polyethylene matrix, 18-35 parts of reinforcing compound and 4-6 parts of composite additives; The reinforcing composite material is composed of glass fiber, carbon fiber and maleic anhydride-grafted polyethylene. The composite additives include flame retardants, lubricants, and antioxidants.

2. The wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene according to claim 1, characterized in that: The ultra-high molecular weight polyethylene has a molecular weight greater than 1 million and a density of 0.935-0.945 g / cm³. 3 .

3. The ultra-high molecular weight polyethylene according to claim 2, characterized in that: The ultra-high molecular weight polyethylene has a molecular weight of 2 million to 4 million.

4. The wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene according to any one of claims 1-3, characterized in that: In the reinforcing composite material, the mass ratio of glass fiber, carbon fiber and maleic anhydride grafted polyethylene is (10~20):(5~10):(3~5).

5. The wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene according to any one of claims 1-3, characterized in that, In the composite additive, the mass ratio of the flame retardant, lubricant and antioxidant is (1.5-2.5):(1.5-2.5):

1.

6. The wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene according to any one of claims 1-3, characterized in that, The flame retardant includes decabromodiphenyl ether and antimony trioxide; the lubricant includes PE wax and molybdenum disulfide.

7. A method for preparing the wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Mix the raw materials according to the above mass proportions, stir evenly, and obtain a mixture; (2) The mixture is placed in an extruder and plasticized into a viscous flow state under high temperature and high pressure melting. After extrusion and drawing, it is cooled and granulated to obtain wear-resistant and corrosion-resistant ultra-high molecular weight polyethylene material.

8. The method for preparing ultra-high molecular weight polyethylene according to claim 7, characterized in that, In step (2), the extruder is a conical twin-screw extruder with a barrel temperature of 7 zones, ranging from low to high: zone 1 160℃, zone 2 165℃, zone 3 170℃, zone 4 175℃, zone 5 180℃, zone 6 185℃, and zone 7 180℃; melt pressure 20MPa-25MPa; feed speed 88r / min~10r / min; cooling is achieved by using cooling water with a flow rate range of 8t / h~12t / h and a temperature range of 0℃~10℃.