Ultra-high molecular weight polyethylene material rich in double bonds and capable of maintaining long straight chain structure and preparation method of ultra-high molecular weight polyethylene material
By swelling and irradiating ultra-high molecular weight polyethylene under anaerobic conditions, the problems of molecular chain cross-linking and degradation were solved, and the double bonds were successfully introduced and their long straight chain structure was maintained, achieving high mechanical properties and chemical activity. Improvement.
Patent Information
- Application Number
- CN202411332183.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2024-12-27
AI Technical Summary
When the prior art introduces double bond structures into ultra-high molecular weight polyethylene, it is easy to cause molecular chain cross-linking and degradation reactions, destroying its long straight chain structure and high mechanical properties.
By swelling ultra-high molecular weight polyethylene materials in organic solvents and irradiating with high energy rays under anaerobic conditions, the swelling and irradiation dose are controlled to inhibit crosslinking reactions and degradation and maintain the long straightness of the molecular chain chain structure, and simultaneously introduce controllable carbon-carbon double bonds.
The double bonds were successfully introduced into ultra-high molecular weight polyethylene to improve chemical activity while retaining its high mechanical properties and long linear structure, achieving the acquisition of a variety of functionalized structures.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of orthopedic implant manufacturing, and in particular to an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure and a preparation method thereof. Background Art
[0002] Ultra-high molecular weight polyethylene (UHMWPE) is an unbranched linear polyethylene with a molecular weight of more than 1.5 million. The ultra-long saturated carbon-carbon straight chain structure gives UHMWPE good mechanical properties, corrosion resistance, and biocompatibility, and has important applications in biomedicine, aerospace, wires and cables, etc. At the same time, this structure also makes the chemical modification and modification of UHMWPE extremely difficult. In the field of polyolefin functionalization, a variety of functionalized polymers can be obtained through various reaction pathways using carbon-carbon double bonds as modified functional groups.
[0003] The traditional ways to introduce double bonds into the ultra-high molecular weight polyethylene molecular chain mainly include copolymerization and radiation modification. The copolymerization method is to copolymerize polyethylene with multi-double bond monomers such as maleic acid and divinylbenzene to obtain a polymer material with a double bond structure. However, the copolymerization method will significantly reduce the molecular weight of the polymer and produce side chains, and linear ultra-high molecular weight polyethylene materials cannot be obtained, and the mechanical properties of the material are poor. The radiation modification method is to use high-energy rays to irradiate UHMWPE to produce double bonds through dehydrogenation reactions. However, conventional radiation-modified UHMWPE mainly undergoes cross-linking and degradation reactions. The former causes the molecular chain to form a cross-linked network structure, and the latter causes the molecular chain to break. Both reactions greatly destroy the long straight chain characteristics of UHMWPE, thereby reducing the already difficult processing performance of UHMWPE.
[0004] Therefore, it is of certain practical significance to develop a UHMWPE material containing double bonds and maintaining a long straight chain structure, which can not only retain the high mechanical properties of ultra-high molecular weight polyethylene, but also utilize double bonds to obtain a variety of functional structures. Summary of the invention
[0005] The object of the present invention is to provide a method for preparing an ultra-high molecular weight polyethylene material which is rich in double bonds and maintains a long straight chain structure. The preparation method can introduce a controllable number of carbon-carbon double bonds into the ultra-high molecular weight polyethylene molecular chain without changing the molecular weight and long straight chain structural characteristics of the ultra-high molecular weight polyethylene, thereby enabling the ultra-high molecular weight polyethylene material to obtain excellent chemical activity.
[0006] In a first aspect, the present invention provides a method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, comprising the following steps:
[0007] S1. The ultra-high molecular weight polyethylene material is placed in an organic solvent for swelling to obtain a gel material;
[0008] S2. Under anaerobic conditions, irradiating the gel material with high-energy rays;
[0009] S3. removing the organic solvent in the irradiated gel material to obtain the ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure.
[0010] As described in the background technology, conventional radiation-modified ultra-high molecular weight polyethylene mainly undergoes cross-linking and degradation reactions. The former causes the molecular chains to form a cross-linked network structure, and the latter causes the molecular chains to break. Both reactions greatly destroy the long straight chain characteristics of ultra-high molecular weight polyethylene, thereby reducing the already difficult processing performance of ultra-high molecular weight polyethylene.
[0011] In the present invention, the inventors found that by selecting a suitable organic solvent to swell the ultra-high molecular weight polyethylene material and controlling a certain swelling degree, the molecular chains of the ultra-high molecular weight polyethylene material can be completely separated, thereby effectively suppressing the degree of cross-linking reaction between the molecular chains during the subsequent irradiation process, thereby maintaining the long straight chain structure of the ultra-high molecular weight polyethylene material. Therefore, the preparation method provided by the present invention can not only introduce double bonds into the ultra-high molecular weight polyethylene material, so as to obtain a variety of functionalized structures by using double bonds, but also retain the characteristics of high mechanical properties of ultra-high molecular weight polyethylene.
[0012] In step S1 of the present invention, the organic solvent needs to be a good solvent for polyolefin materials, capable of achieving swelling of ultra-high molecular weight polyethylene materials; and has good stability under irradiation conditions to avoid side reactions during irradiation. The organic solvent is an organic solvent containing a benzene ring, for example, it can be at least one of toluene and xylene, preferably xylene. Xylene can fully dissolve the crystalline region of the ultra-high molecular weight polyethylene material to achieve complete separation between molecular chains.
[0013] Granular ultra-high molecular weight polyethylene materials contain a large amount of dissolved oxygen, which is difficult to remove by conventional means, resulting in easy radiation degradation during irradiation, which causes molecular chains to break, destroys the long straight chain structure of UHMWPE, and reduces the molecular weight. Swelling granular ultra-high molecular weight polyethylene materials with toluene and xylene can effectively remove the dissolved oxygen contained in the granular ultra-high molecular weight polyethylene materials and provide an inert environment, thereby inhibiting the degradation reaction during irradiation.
[0014] In some preferred embodiments of the present invention, in the above step S1, the viscosity average molecular weight of the ultra-high molecular weight polyethylene material needs to be within 1.0×10 6 Above, preferably 3.0×10 6The shape of the ultra-high molecular weight polyethylene material is not limited and can be various shapes such as fine particles, blocks, films, pellets or fibers.
[0015] In step S1 of the present invention, the ultra-high molecular weight polyethylene material is subjected to a swelling treatment to achieve a certain swelling degree, and the swelling degree can be calculated according to the following formula:
[0016]
[0017] Wherein, M1 is the mass of ultra-high molecular weight polyethylene before swelling, and M2 refers to the mass of ultra-high molecular weight polyethylene after swelling.
[0018] In step S1 of the present invention, the swelling degree of the ultra-high molecular weight polyethylene material needs to be controlled within the range of 0.5 to 30, for example, 0.5, 1, 2, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, etc. Preferably, the swelling degree is controlled within the range of 2 to 10. When the swelling degree is greater than 2, the cross-linking reaction induced by radiation can be fully limited.
[0019] In some preferred embodiments of the present invention, in the above step S1, the swelling is preferably carried out under heating conditions, and the heating temperature may be 110-130° C., such as 110° C., 115° C., 120° C., 125° C., 130° C., etc. The duration of the swelling may be 5-10 h, such as 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc.
[0020] In step S1 of the present invention, after the swelling is completed, the ultra-high molecular weight polyethylene material needs to be stored in a sealed manner to prevent the volatilization of the organic solvent from causing a decrease in the swelling degree.
[0021] In step S2 of the present invention, the oxygen-free condition includes a vacuum or an inert atmosphere, and the inert atmosphere includes at least one of nitrogen, helium, and argon.
[0022] In step S2 of the present invention, the high-energy rays include at least one of electron beams, gamma rays, and X-rays, preferably gamma rays.
[0023] In the present invention, the dosage range of high-energy rays is nearly proportional to the carbon-carbon double bond content in the final product. By controlling the irradiation dose, the carbon-carbon double bond content in the ultra-high molecular weight polyethylene can be regulated. In some embodiments, the irradiation dose range is 5 to 2000 kGy, for example, it can be 5 kGy, 10 kGy, 50 kGy, 100 kGy, 200 kGy, 500 kGy, 800 kGy, 1000 kGy, 2000 kGy, etc.
[0024] In the present invention, the dose rate range of irradiation is determined according to the irradiation source. When γ-ray or X-ray irradiation is used, the dose rate range is 0.1 to 10 kGy / h; when electron beam irradiation is used, the dose rate range is 1 to 10000 kGy / h. Avoid using too high a dose rate, which may cause the sample to heat up sharply.
[0025] The second aspect of the present invention provides an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, which is prepared by the above method.
[0026] Through one or more of the above embodiments of the present invention, at least the following technical effects can be achieved:
[0027] 1. The present invention prepares an ultra-high molecular weight polyethylene material rich in double bond structure through a swelling irradiation method. The preparation method can control the number of double bonds in the material, thereby obtaining excellent chemical activity; in addition, the preparation method effectively inhibits the cross-linking reaction between molecular chains, thereby maintaining the long straight chain structure of the ultra-high molecular weight polyethylene material, and its crystal structure and physical properties are similar to those of ordinary ultra-high molecular weight polyethylene, thereby retaining the excellent mechanical properties of ultra-high molecular weight polyethylene.
[0028] 2. The present invention introduces a controllable number of carbon-carbon double bonds into the ultra-high molecular weight polyethylene molecular chain without changing the molecular weight and long straight chain structure characteristics of the ultra-high molecular weight polyethylene. The material is an ideal intermediate for preparing modified ultra-high molecular weight polyethylene materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 IR spectra of Examples 1-4 and raw material (0). DETAILED DESCRIPTION
[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.
[0031] 1. The calculation method of double bond content in ultra-high molecular weight polyethylene materials can refer to the literature: POLYMER LETTERSVOL.2, P339-341 (1964). The specific calculation method is as follows:
[0032] The infrared characteristic absorption peak of the -CH=CH- double bond in the ultra-high molecular weight polyethylene molecular formula is located at 965cm -1 , its extinction coefficient is 169 l·cm -1, the double bond content was calculated according to the Lambert-Beer law.
[0033] A=εcL=-lg(I / I0)
[0034] Where:
[0035] A-absorbance;
[0036] ε-extinction coefficient (l·cm -1 );
[0037] c- molar concentration of the sample (mmol / l);
[0038] L-thickness of sample (cm);
[0039] I0-incident light intensity;
[0040] I - transmitted light intensity.
[0041] 2. The viscosity test of the dilute solution of ultra-high molecular weight polyethylene material is carried out according to the viscosity test method of polyolefin dilute solution GB / T1632.3-2010 or ISO1628-3:2001, using a high-temperature Ubbelohde viscometer. The viscosity method is to calculate the relative molecular mass by measuring the intrinsic viscosity. Calculation is based on the Mark-Houwink equation:
[0042] Lg[η]=lg K+αlg M
[0043] M=K[η] α
[0044] Where K = 5.37 × 104, α = 1.37, (ASTM standard).
[0045] Example 1
[0046] This embodiment provides a method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, comprising the following steps:
[0047] S1. Take 5g of UHMWPE original powder fine particles with a molecular weight of 3 million, place them in 100g of xylene solvent, swell them at 110°C for 2h, cool them to room temperature, filter out excess xylene, and obtain a jelly-like ultra-high molecular weight gel. The swelling ratio is calculated by weighing and is about 8.4.
[0048] S2. The gel was sealed in a glass bottle, protected by nitrogen, and irradiated with gamma rays at a dose rate of 10 kGy / h to a total absorbed dose of 500 kGy.
[0049] S3. The irradiated UHMWPE gel was placed in a vacuum oven and dried at 100°C for 24 h to remove xylene, and 4.7 g of the target sample was obtained.
[0050] Cut a 0.3 mm slice from the dried sample and perform infrared testing and analysis. The infrared spectrum is as follows: Figure 1 shown.
[0051] It can be seen from the figure that the sample has a -1 The characteristic infrared absorption peak of trans-vinylidene is clearly seen at , with an absorbance A of 0.356. According to the formula c=A / (εL), the double bond concentration is calculated to be 70.2 mmol / l.
[0052] The molecular weight of the ultra-high molecular weight polyethylene material was determined by high temperature viscosity method to be 3.2×10 6 .
[0053] Example 2
[0054] This embodiment provides a method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, comprising the following steps:
[0055] S1. Take a UHMWPE rod with a molecular weight of 3 million and a diameter of 50 mm, and cut a test sample with a thickness of 1 cm and a mass of about 18 g from the rod. Put the sample into 50 g of xylene solvent, swell at 130°C for 3 hours, cool to room temperature, remove excess xylene, and obtain a jelly-like ultra-high molecular weight gel. The swelling ratio is calculated by weighing and is about 8.4.
[0056] S2. The gel is placed in a glass bottle, nitrogen is quickly introduced and the bottle is sealed, and irradiated with gamma rays at a dose rate of about 5 kGy / h to a total absorbed dose of 250 kGy.
[0057] S3. The irradiated UHMWPE gel was placed in a vacuum oven and dried at 100°C for 48 h to remove xylene, and 17.9 g of the target sample was obtained.
[0058] Cut a 0.3mm slice from the dried sample for infrared testing and analysis. The infrared spectrum is as follows: Figure 1 shown.
[0059] The absorbance A of the sample is 0.221. According to the formula c = A / (εL), the double bond concentration is calculated to be 43.4 mmol / l. The molecular weight is 3.4×10 6 .
[0060] Example 3
[0061] This embodiment provides a method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, comprising the following steps:
[0062] S1. Take a piece of UHMWPE skived film with a molecular weight of 3 million, 100mm×100mm, thickness of 300 microns, weight of 2.8g, place it in a glass container, fully immerse it in 100g of xylene, swell it at 120℃ for 2h, cool it to room temperature, quickly take out and drain the xylene on the surface to obtain a jelly-like ultra-high molecular weight gel, and weigh and calculate the swelling ratio to be about 5.2.
[0063] S2. The gel is placed flat in a radiation-resistant sealed bag, evacuated, and sealed. The sealed bag is placed on a metal tray and irradiated with an electron beam at a dose of 250 kGy for 30 minutes.
[0064] S3. After irradiation, the UHMWPE gel was taken out and dried in a vacuum oven at 100°C for 24 hours to remove xylene, and 2.7 g of the target sample was obtained. The sample was still a complete film.
[0065] Cut a 0.3mm slice from the dried sample for infrared testing and analysis. The infrared spectrum is as follows: Figure 1 shown.
[0066] The sample absorbance A is 0.161. According to the formula c = A / (εL), the double bond concentration is calculated to be 43.4mmol / l. The molecular weight is 4.1×10 6 .
[0067] Example 4
[0068] This embodiment provides a method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, comprising the following steps:
[0069] S1. Take a piece of UHMWPE skived film with a molecular weight of 3 million, 100mm×100mm, thickness of 300 microns, weight of 2.8g, place it in a glass container, fully immerse it in 100g of xylene, swell it at 120℃ for 2h, cool it to room temperature, quickly take out and drain the xylene on the surface to obtain a jelly-like ultra-high molecular weight gel, and weigh and calculate the swelling ratio to be about 5.2.
[0070] S2. The gel was placed flat in a radiation-resistant sealed bag, evacuated, and sealed. The sealed bag was placed on a metal tray and irradiated with an electron beam at a dose of 100 kGy for 30 minutes.
[0071] S3. After irradiation, the UHMWPE gel was taken out and dried in a vacuum oven at 100°C for 24 hours to remove xylene, and 2.7 g of the target sample was obtained. The sample was still a complete film.
[0072] Cut a 0.3mm slice from the dried sample for infrared testing and analysis. The infrared spectrum is as follows: Figure 1 shown.
[0073] The sample absorbance A is 0.124. According to the formula c = A / (εL), the double bond concentration is calculated to be 24.4mmol / l. The molecular weight is 3.6×10 6 .
[0074] Example 5
[0075] This embodiment provides a method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, comprising the following steps:
[0076] S1. Take a piece of UHMWPE skived film with a molecular weight of 3 million, 100mm×100mm, thickness of 300 microns, weight of 2.8g, place it in a glass container, fully immerse it in 100g toluene, swell it at 120℃ for 2h, cool it to room temperature, quickly take out and drain the toluene on the surface to obtain a jelly-like ultra-high molecular weight gel, and weigh and calculate the swelling ratio to be about 5.2.
[0077] S2. The gel was placed flat in a radiation-resistant sealed bag, evacuated, and sealed. The sealed bag was placed on a metal tray and irradiated with an electron beam at a dose of 100 kGy for 30 minutes.
[0078] S3. After irradiation, the UHMWPE gel was taken out and dried in a vacuum oven at 100°C for 24 h to remove toluene, and 2.7 g of the target sample was obtained. The sample was still a complete film.
[0079] Cut a 0.3mm slice from the dried sample for infrared testing and analysis. The infrared spectrum is as follows: Figure 1 shown.
[0080] The sample absorbance A is 0.131. According to the formula c = A / (εL), the double bond concentration is calculated to be 25.6mmol / l. The molecular weight is 3.5×10 6 .
[0081] Comparative Example 1
[0082] The raw materials of this comparative example are the same as those of Example 1. A sample weighing about 18 g is directly irradiated with gamma rays under the same irradiation conditions as those of Example 1. After irradiation, the sample weighs 17.9 g.
[0083] The sample was sliced and analyzed by infrared testing at 965cm -1 The characteristic infrared absorption peak of trans-vinylidene obviously appeared, and the double bond concentration was calculated to be 40.7mmol / l.
[0084] The sample was swollen with sufficient 130°C xylene for 10 hours, and the swelling degree was 2.3, indicating that the sample had been deeply radiation cross-linked to form a network macromolecular structure, and the molecular weight could not be determined.
[0085] Comparative Example 2
[0086] The raw materials are the same as those in Example 2, and a sample weighing about 5 g is taken, placed directly in a glass container without any treatment, and irradiated with gamma rays in air under the same irradiation conditions as in Example 2. After irradiation, the sample weighs 5.4 g.
[0087] The dried samples were subjected to infrared testing and analysis at 965cm -1 The characteristic infrared absorption peak of trans-vinylidene obviously appeared, and the double bond concentration was calculated to be 31.2 mmol / l.
[0088] The molecular weight was determined by high temperature viscosity method and was 0.8×10 6 , showing radiation oxidative degradation.
[0089] According to the above test results, it can be seen that in Examples 1-4, the irradiation treatment introduces a large number of carbon-carbon double bonds into the UHMWPE material, and there is a certain relationship between the concentration of carbon-carbon double bonds and the irradiation dose and the swelling degree. Therefore, the concentration of carbon-carbon double bonds in the UHMWPE material can be controlled by adjusting the irradiation dose and the swelling degree.
[0090] Secondly, in Examples 1-4, after the swelling treatment and the irradiation treatment, the molecular weight of the UHMWPE material remained basically unchanged, or increased slightly, which indicates that the swelling treatment of the UHMWPE material with xylene can effectively inhibit the cross-linking reaction between the UHMWPE molecular chains.
[0091] It can be seen from the results of Examples 1 and 5 that the results of using xylene and toluene as solvents are similar and there is no obvious difference.
[0092] Comparative Example 1-2 is acceptable. When only conventional irradiation is performed, UHMWPE also produces double bonds, but the block raw material will undergo a cross-linking reaction, and the powdered granular raw material contains a large amount of dissolved oxygen, which cannot be completely removed. Therefore, radiation oxidation degradation reaction will occur during the irradiation process. Both reactions cause the raw material to lose its original long straight chain structure.
[0093] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.
Claims
1. A method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, characterized in that: The following steps are involved: S1. placing an ultra-high molecular weight polyethylene material in an organic solvent for swelling to obtain a gel material; wherein the organic solvent is an organic solvent containing a benzene ring; S2. Under anaerobic conditions, irradiating the gel material with high-energy rays; S3. removing the organic solvent in the irradiated gel material to obtain the ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure.
2. The method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure according to claim 1, characterized in that: In step S1, the organic solvent includes at least one of toluene and xylene.
3. The method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure according to claim 1, characterized in that: In step S1, the swelling is carried out under heating conditions, and the heating temperature is 110-130° C.; and / or, The swelling time is 5 to 10 hours.
4. The method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure according to claim 1, characterized in that: In step S1, the viscosity average molecular weight of the ultra-high molecular weight polyethylene material is 1.0×10 6 above; and / or, The ultra-high molecular weight polyethylene material is in the form of block material, film, pellet or fiber.
5. The method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure according to claim 1, characterized in that: In step S1, the swelling degree of the gel material is 0.5-30.
6. The method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure according to claim 1, characterized in that: In step S2, the swelling degree of the gel material is 2-10.
7. The method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure according to claim 1, characterized in that: In step S2, the oxygen-free condition includes vacuum or an inert atmosphere, and the inert atmosphere includes at least one of nitrogen, helium, and argon.
8. The method for preparing an ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure according to claim 1, characterized in that: In step S2, the high-energy rays include at least one of electron beams, gamma rays, and X-rays; and the irradiation dose ranges from 5 to 2000 kGy.
9. The method for preparing an ultra-high molecular weight polyethylene material rich in and retaining long straight chain double bonds according to claim 1, characterized in that: In step S2, when γ-ray or X-ray irradiation is used, the dose rate range is 0.1 to 10 kGy / h; When electron beam irradiation is used, the dose rate ranges from 1 to 10000 kGy / h.
10. An ultra-high molecular weight polyethylene material rich in double bonds and maintaining a long straight chain structure, prepared by the method according to any one of claims 1 to 9.