Recovery method of waste ultra-high molecular weight polyethylene
By combining high-temperature transient shearing and low-temperature shearing and grinding, the problem of recycling waste ultra-high molecular weight polyethylene has been solved, achieving efficient and environmentally friendly resource recycling and improving the material's performance and utilization value.
Patent Information
- Application Number
- CN202511181843.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-22
- Publication Date
- 2025-11-18
AI Technical Summary
Existing technologies are insufficient for the efficient recycling of waste ultra-high molecular weight polyethylene. Furthermore, the performance of recycled materials obtained through physical methods is reduced, while chemical methods are inefficient and uneconomical, leading to resource waste and environmental pollution.
A combined process of high-temperature transient shearing, low-temperature shearing and grinding, and vibrating screening is used to process waste ultra-high molecular weight polyethylene through a two-roll mill and a solid-phase shearing mill, refining it into flakes and screening it to obtain recycled polyethylene that can be directly added to the market.
It achieves efficient and environmentally friendly recycling of waste ultra-high molecular weight polyethylene, maintaining its original properties. The refined material can be directly added for reuse or used as an additive to modify other polymers, thus improving the value of resource utilization.
Smart Images
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of recycling and regenerating waste thermoplastic engineering plastics, and particularly relates to a recycling method of waste ultrahigh molecular weight polyethylene. BACKGROUND
[0002] Among numerous plastic varieties, ultrahigh molecular weight polyethylene is a new emerging engineering plastic with excellent performance, and its viscosity average molecular weight is 150*10 4 The above-mentioned ultrahigh molecular weight polyethylene is non-toxic, not easy to absorb water, not easy to adhere, impact-resistant, wear-resistant, and resistant to chemical corrosion, and is widely used in key fields such as textiles, papermaking, medical treatment, aerospace, metallurgy, and coal. However, the large molecular weight and high entanglement density of the ultrahigh molecular weight polyethylene result in a melt viscosity of 10 8 Pa·s, and a very low critical shear rate, which makes the molding process extremely difficult.
[0003] In addition, the ultrahigh molecular weight polyethylene needs to be subjected to secondary processing such as cutting and grinding after primary molding, which produces a large amount of waste edge materials that are difficult to reuse. With the continuous development of the molding process of ultrahigh molecular weight polyethylene, the application field and the amount of ultrahigh molecular weight polyethylene are also increasing. At present, the amount of ultrahigh molecular weight polyethylene in the world exceeds 54.3 million tons per year, and the amount of ultrahigh molecular weight polyethylene in China also exceeds 230 million tons per year. It is estimated that the amount of ultrahigh molecular weight polyethylene in the world will double in five years. With the rapid increase in the amount of ultrahigh molecular weight polyethylene, the amount of ultrahigh molecular weight polyethylene waste produced during processing and after use will also significantly increase.
[0004] At present, the methods for recycling waste ultrahigh molecular weight polyethylene reported in the public domain mainly include chemical methods and physical methods. The chemical method mainly promotes the degradation of ultrahigh molecular weight polyethylene by adding catalysts and other chemicals to reduce the molecular weight. However, this method is economically unfeasible, has low efficiency, and the target product is not pure, which makes industrialization difficult. The physical method for recycling waste ultrahigh molecular weight polyethylene mainly includes crushing and grinding the waste ultrahigh molecular weight polyethylene to replace part of the new ultrahigh molecular weight polyethylene or use it as an additive. Although the physical method does not involve the addition of chemicals and does not cause secondary pollution, it is relatively environmentally friendly. However, the size of the regenerated ultrahigh molecular weight polyethylene obtained by the physical method is usually relatively large (average particle size ≥ 0.5 mm), which can only play the role of a thermosetting filler, thereby reducing the performance of the product, and the energy consumption of the grinding equipment is high.
[0005] Therefore, in view of the problems existing in the methods for recycling waste ultrahigh molecular weight polyethylene, it is necessary to develop a new and efficient recycling method. SUMMARY
[0006] The present application aims at providing a waste ultra-high molecular weight polyethylene recycling method to solve the problems of the prior art, which can finely grind the ultra-high molecular weight polyethylene in an environmentally friendly and efficient manner, so that the ground waste ultra-high molecular weight polyethylene can be directly added back for use or used as an additive to modify other polymers, and the efficient and high-value utilization of the waste ultra-high molecular weight polyethylene is realized.
[0007] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions.
[0008] The present application provides a waste ultra-high molecular weight polyethylene recycling method, which comprises the following steps:
[0009] 1) cutting the waste ultra-high molecular weight polyethylene products to obtain block-shaped materials;
[0010] 2) crushing the block-shaped materials into sheet-shaped materials after high-temperature transient shearing treatment;
[0011] 3) low-temperature shearing grinding the sheet-shaped materials, and vibrating and screening the ground materials to obtain regenerated ultra-high molecular weight polyethylene.
[0012] Preferably, the waste ultra-high molecular weight polyethylene products in step 1) are ultra-high molecular weight polyethylene pipes, plates, sheets or profiles discarded after use or in the factory.
[0013] Preferably, the filler mass fraction of the waste ultra-high molecular weight polyethylene products in step 1) is 5-10%, and the relative molecular mass is 2-4 million.
[0014] Preferably, the length of the block-shaped materials in step 1) is 10-15 cm, the width is 10-15 cm, and the height is 4-6 cm.
[0015] Preferably, the high-temperature transient shearing treatment in step 2) is carried out in a double-roller open mill, the temperature of the roller is 155-165℃, the roll gap is 1-6 mm, the shearing rate is 1-3 s -1 .
[0016] Preferably, the longest side length of the sheet-shaped materials in step 2) is 1-1.5 cm.
[0017] Preferably, the low-temperature shearing grinding in step 3) is carried out in a solid-phase shearing grinder, the rotating speed of the grinding disc is 150-400 r / min, the grinding pressure is 1-2 MPa, and the grinding cycle is 1-6 times.
[0018] Preferably, in the low-temperature shearing grinding process in step 3), the heat is taken away by circulating cooling water, and the temperature of the circulating cooling water is 5-20℃.
[0019] Preferably, the vibrating screening in step 3) uses a screen with a mesh size of ≥30 meshes.
[0020] The beneficial effects of the present application include the following points:
[0021] 1) The recycling method of the present application can promote the fine recycling of waste ultrahigh molecular weight polyethylene by utilizing the coupling effect of high and low temperature on the basis of ensuring that the excellent performance of ultrahigh molecular weight polyethylene will not be greatly reduced.
[0022] 2) The present application can skillfully avoid the processing problems caused by the high viscosity of ultrahigh molecular weight polyethylene by using high-temperature transient shearing, and in this process, there is no chemical action and no "three wastes", so that the ultrahigh molecular weight polyethylene can be recycled efficiently and environmentally, achieving the true sense of solid waste recycling and resource utilization.
[0023] 3) The recycling method of the present application is simple and efficient, and can effectively realize the fine disposal of waste ultrahigh molecular weight polyethylene which is difficult to recycle. The fine waste ultrahigh molecular weight polyethylene can be directly added back for use or used as an additive to modify other polymers, realizing efficient and high-value utilization of waste ultrahigh molecular weight polyethylene. DETAILED DESCRIPTION
[0024] The present application provides a recycling method of waste ultrahigh molecular weight polyethylene, comprising the following steps:
[0025] 1) Cutting the waste ultrahigh molecular weight polyethylene product to obtain a block;
[0026] 2) High-temperature transient shearing treatment is performed on the block to break it into a flaky material;
[0027] 3) Low-temperature shearing and grinding are performed on the flaky material, and vibration screening is performed on the ground material to obtain regenerated ultrahigh molecular weight polyethylene.
[0028] In the present application, the waste ultrahigh molecular weight polyethylene product of step 1) is preferably ultrahigh molecular weight polyethylene pipe, plate, sheet or profile material that is used or discarded by the factory.
[0029] In the present application, the profile refers to a product with a cross-sectional shape that does not belong to a standard profile such as a regular circle, square, rectangle, etc., and usually has special structures such as asymmetric, grooves, bosses, curved surfaces, multiple cavities, etc.
[0030] In the present application, the filler mass fraction of the waste ultrahigh molecular weight polyethylene product of step 1) is preferably 5-10%, further preferably 6-8%, and more preferably 7%, and the relative molecular mass is preferably 2-4 million, further preferably 2.5-3.5 million, and more preferably 3 million.
[0031] In the present application, the length of the block in step 1) is preferably 10-15 cm, further preferably 12-14 cm, and more preferably 13 cm; the width is preferably 10-15 cm, further preferably 12-14 cm, and more preferably 13 cm; and the height is preferably 4-6 cm, further preferably 4.5-5.5 cm, and more preferably 5 cm.
[0032] In the present application, the high-temperature transient shear treatment in step 2) is preferably performed in a two-roll open mill, the temperature of the roll is preferably 155-165℃, further preferably 158-162℃, and more preferably 160℃, the roll gap is preferably 1-6 mm, further preferably 2-4 mm, and more preferably 3 mm, and the shear rate is preferably 1-3 s -1 , further preferably 1.5-2.5 s -1 , and more preferably 2 s -1 .
[0033] In the present application, the length of the longest side of the sheet in step 2) is preferably 1-1.5 cm, further preferably 1.2-1.4 cm, and more preferably 1.3 cm.
[0034] In the present application, the length of the longest side of the sheet refers to the maximum linear dimension of the external shape of a single sheet particle. When measuring, place the sheet on a horizontal surface, use a vernier caliper to measure the maximum distance between any two points on the external contour, and record it as the length of the longest side of the sheet. For irregularly shaped sheets, the straight-line distance between the two outermost points should be used as the measurement result.
[0035] In the present application, the low-temperature shear milling in step 3) is preferably performed in a solid-phase shear mill, the rotation speed of the millstone is preferably 150-400 r / min, further preferably 200-350 r / min, and more preferably 250-300 r / min, the milling pressure is preferably 1-2 MPa, further preferably 1.4-1.6 MPa, and more preferably 1.5 MPa, and the milling cycle is preferably 1-6 times, further preferably 2-4 times, and more preferably 3 times.
[0036] In the present application, the solid-phase shear mill is preferably a millstone-shaped solid-phase force chemical reactor, which is composed of a fixed millstone and a rotating millstone. The fixed millstone is fixed on the shell, and the rotating millstone is fixed on the rotating shaft of the bracket. The two are meshed with each other and arranged transversely. The rotating millstone is driven to rotate by a motor-driven transmission device. A hydraulic system is used to adjust the distance or pressure of the millstone surface. The material continuously enters the millstone for force reaction through the feed screw from the feeding hopper. The reactants are discharged from the discharge port through the feed pipe.
[0037] In the present application, the large particle waste ultrahigh molecular weight polyethylene is added into the solid phase shear mill, and is fed from the feeding port of the equipment to the discharge port, which is called a first grinding cycle.
[0038] In the present application, the low-temperature shear grinding process in step 3) preferably removes heat by circulating cooling water, and the temperature of the circulating cooling water is preferably 5-20°C, and further preferably 10-15°C.
[0039] In the present application, the vibration screening in step 3) preferably uses a screen with a mesh size of ≥30 meshes, further preferably a mesh size of ≥35 meshes, and more preferably a mesh size of ≥40 meshes.
[0040] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.
[0041] Example 1
[0042] The waste ultrahigh molecular weight polyethylene sheet with a filler mass fraction of 6% and a relative molecular mass of 3.5 million is cut into blocks with a length of 10 cm, a width of 10 cm, and a height of 4 cm by a cutting machine, and then the blocks are subjected to high-temperature transient shear treatment in a two-roll open mill, with the temperature of the roll being 160°C, the roll gap being 3 mm, and the shear rate being 3 s -1 After that, the blocks are crushed into sheet-shaped objects with a longest side length of 1 cm by a crusher, and then the sheet-shaped objects are subjected to low-temperature shear grinding in a solid phase shear mill for one cycle, with the rotating speed of the grinding disc being 150 r / min and the grinding pressure being 1.3 MPa, and the heat generated during the grinding process is removed by circulating cooling water with a temperature of 10°C. Finally, the ground material is subjected to vibration screening through a screen with a mesh size of 30 meshes, and the regenerated ultrahigh molecular weight polyethylene is obtained.
[0043] Example 2
[0044] The waste ultrahigh molecular weight polyethylene pipe with a filler mass fraction of 5% and a relative molecular mass of 2 million is cut into blocks with a length of 15 cm, a width of 15 cm, and a height of 6 cm by a cutting machine, and then the blocks are subjected to high-temperature transient shear treatment in a two-roll open mill, with the temperature of the roll being 165°C, the roll gap being 6 mm, and the shear rate being 2 s -1 After that, the blocks are crushed into sheet-shaped objects with a longest side length of 1.5 cm by a crusher, and then the sheet-shaped objects are subjected to low-temperature shear grinding in a solid phase shear mill for four cycles, with the rotating speed of the grinding disc being 250 r / min and the grinding pressure being 2 MPa, and the heat generated during the grinding process is removed by circulating cooling water with a temperature of 15°C. Finally, the ground material is subjected to vibration screening through a screen with a mesh size of 40 meshes, and the regenerated ultrahigh molecular weight polyethylene is obtained.
[0045] Example 3
[0046] The waste UHMWPE plate with filler mass fraction of 10% and relative molecular mass of 4 million was cut into blocks with length of 12 cm, width of 12 cm and height of 5 cm by a cutting machine, and then the blocks were subjected to high-temperature transient shear treatment in a two-roll open mill, the temperature of the roll was 155 ℃, the roll gap was 1 mm, and the shear rate was 1 s -1 After that, the waste UHMWPE plate was crushed into flakes with the longest side length of 1.2 cm by a crusher, and then the flakes were subjected to low-temperature shear milling for 3 cycles in a solid-phase shear mill, the rotating speed of the millstone was 400 r / min, the milling pressure was 1 MPa, and the heat generated during the milling process was removed by circulating cooling water with a temperature of 8 ℃, and finally the milled material was subjected to vibration screening through a screen with a mesh number of 30, to obtain the regenerated UHMWPE.
[0047] Example 4
[0048] The waste UHMWPE sheet with filler mass fraction of 8% and relative molecular mass of 3 million was cut into blocks with length of 13 cm, width of 12 cm and height of 4.5 cm by a cutting machine, and then the blocks were subjected to high-temperature transient shear treatment in a two-roll open mill, the temperature of the roll was 160 ℃, the roll gap was 4 mm, and the shear rate was 2 s -1 After that, the waste UHMWPE plate was crushed into flakes with the longest side length of 1.4 cm by a crusher, and then the flakes were subjected to low-temperature shear milling for 2 cycles in a solid-phase shear mill, the rotating speed of the millstone was 300 r / min, the milling pressure was 1.5 MPa, and the heat generated during the milling process was removed by circulating cooling water with a temperature of 5 ℃, and finally the milled material was subjected to vibration screening through a screen with a mesh number of 50, to obtain the regenerated UHMWPE.
[0049] Example 5
[0050] The waste UHMWPE profile (cross-section with “T” type structure) with filler mass fraction of 7% and relative molecular mass of 3.6 million was cut into blocks with length of 14 cm, width of 13 cm and height of 5.5 cm by a cutting machine, and then the blocks were subjected to high-temperature transient shear treatment in a two-roll open mill, the temperature of the roll was 165 ℃, the roll gap was 2 mm, and the shear rate was 3 s -1Afterwards, the waste UHMWPE is broken into pieces with the longest side length of 1.2 cm by a crusher, and then the pieces are placed in a solid-phase shear mill for low-temperature shear milling for 3 cycles, the rotating speed of the millstone is 350 r / min, the milling pressure is 1.3 MPa, the heat generated in the milling process is taken away by circulating cooling water with a temperature of 20 DEG C, finally, the milled material is screened by a sieve with a mesh number of 60, and the regenerated UHMWPE is obtained.
[0051] Comparative Example 1
[0052] The waste UHMWPE with a filler mass fraction of 6% and a relative molecular mass of 3.5 million is broken into pieces with a length of 1 cm by a crusher, and then the pieces are placed in a solid-phase shear mill for low-temperature shear milling for 10 cycles, the rotating speed of the millstone is 150 r / min, the milling pressure is 1.3 MPa, the heat generated in the milling process is taken away by circulating cooling water with a temperature of 10 DEG C, finally, the milled material is screened by a sieve with a mesh number of 30, and the regenerated UHMWPE is obtained.
[0053] The property comparison results of the waste UHMWPE sheet of Example 1 (raw material) and the regenerated UHMWPE prepared in Examples 1-5 and Comparative Example 1 are shown in Table 1.
[0054] Table 1 Property comparison results of different UHMWPE
[0055]
[0056]
[0057] As shown in Table 1, the recycling method can promote the recycling of waste UHMWPE by high-low temperature coupling on the basis of ensuring that the excellent performance of UHMWPE does not decrease substantially, and the fine waste UHMWPE can be directly added for reuse or used as an additive to modify other polymers, so that the efficient and high-value utilization of waste UHMWPE is realized.
[0058] The high-temperature transient shear method can cleverly avoid the processing problems caused by the high solvent viscosity of UHMWPE, and there is no chemical action and no "three wastes" in the process, so that the UHMWPE can be recycled efficiently and environmentally, and the solid waste recycling and resource utilization are achieved in a true sense.
[0059] The above only describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.
Claims
1. A method for recycling waste ultra-high molecular weight polyethylene, characterized in that, It includes the following steps: 1) Cut the waste ultra-high molecular weight polyethylene products to obtain blocks; 2) After subjecting the block to high-temperature transient shearing treatment, it is broken into flakes; 3) The sheet material is subjected to low-temperature shearing and grinding, and the ground material is then vibrated and screened to obtain recycled ultra-high molecular weight polyethylene.
2. The recycling method according to claim 1, characterized in that, Step 1) refers to waste ultra-high molecular weight polyethylene products, which are used or discarded from factories, such as ultra-high molecular weight polyethylene pipes, sheets, plates, or profiles.
3. The recycling method according to claim 2, characterized in that, Step 1) The filler mass fraction of the waste ultra-high molecular weight polyethylene product is 5-10%, and the relative molecular mass is 2 million-4 million.
4. The recycling method according to claim 2 or 3, characterized in that, Step 1) The length of the block is 10-15cm, the width is 10-15cm, and the height is 4-6cm.
5. The recycling method according to claim 4, characterized in that, Step 2) The high-temperature transient shearing treatment is carried out in a two-roll mill, with the roll temperature at 155–165°C, the roll gap at 1–6 mm, and the shearing rate at 1–3 s. -1 .
6. The recycling method according to claim 5, characterized in that, Step 2) The longest side of the sheet-like object is 1 to 1.5 cm.
7. The recycling method according to claim 5 or 6, characterized in that, Step 3) The low-temperature shear grinding is carried out in a solid-phase shear grinding mill, with a grinding disc rotation speed of 150-400 r / min, a grinding pressure of 1-2 MPa, and a grinding cycle of 1-6 times.
8. The recycling method according to claim 7, characterized in that, In step 3), heat is removed by circulating cooling water during the low-temperature shearing and grinding process. The temperature of the circulating cooling water is 5-20℃.
9. The recycling method according to claim 8, characterized in that, Step 3) The vibrating screen used is a screen with a mesh size of ≥30 mesh.