Low-metal-residue cycloolefin polymer as well as preparation method and application thereof

Abstract

The invention provides a low-metal-residue cycloolefin polymer and a preparation method and application thereof, and the preparation method specifically comprises the following steps: (1) mixing a main catalyst, a cocatalyst and an organic solution to obtain a catalyst solution; (2) carrying out ring-opening polymerization reaction on the cycloolefin monomer solution and the catalyst solution, and after the ring-opening polymerization reaction is finished, carrying out hydrogenation reaction to obtain a cycloolefin polymer solution; and (3) adding an adsorbent, and separating to obtain the low-metal residual cycloolefin polymer. According to the adsorbent, hydrophobic groups are grafted on the surface of a molecular sieve, adsorption on polar molecules is reduced, polar metal impurities are preferentially captured, then a template in a pore channel of the molecular sieve is removed through absolute ethyl alcohol, sulfydryl and phenolic hydroxyl are grafted in the pore channel of the molecular sieve, double capture sites are provided, and a metal catalyst left in a cycloolefin polymer solution is chelated; the cycloolefin polymer which is deeply removed and purified can be applied to the field of medical packaging materials, and the safety can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of olefin polymer preparation, and in particular to a low-metal residual cycloolefin polymer and a preparation method and application thereof. Background Art

[0002] Cyclic olefin polymer (COP) is an amorphous, transparent polymer with a highly sterically hindered cyclic alkane structure on its main chain. Due to its excellent transparency, chemical inertness, and biocompatibility, cycloolefin polymer is widely used in pharmaceutical packaging materials such as syringes and medicine bottles. This requires that the residual catalyst metal content in the prepared cycloolefin copolymer must meet certain requirements.

[0003] However, the current preparation of cycloolefin polymers (COPs) is through ring-opening metathesis polymerization. The use of homogeneous catalysts in the ring-opening metathesis polymerization process has high activity and is more efficient when combined with various additives. However, the residual catalyst metals in the final prepared cycloolefin copolymers are relatively high, far from meeting the standards required in the field of pharmaceutical packaging materials.

[0004] Therefore, it is necessary to prepare a low-metal residual cycloolefin polymer to better apply it in the field of pharmaceutical packaging materials and improve safety, which is of practical significance. Summary of the Invention

[0005] In view of this, the present invention provides a low-metal residual cycloolefin polymer and a preparation method and application thereof.

[0006] The technical solution of the present invention is achieved as follows:

[0007] A method for preparing a low-metal residual cycloolefin polymer, comprising the following steps:

[0008] (1) mixing the main catalyst, the co-catalyst and the organic solution to obtain a catalyst solution;

[0009] (2) injecting the cycloolefin monomer solution and the catalyst solution into a reactor to carry out a ring-opening polymerization reaction, and after the ring-opening polymerization reaction is completed, carrying out a hydrogenation reaction to obtain a cycloolefin polymer solution;

[0010] (3) adding an adsorbent to the cycloolefin polymer solution and separating the solution to obtain the target low-metal residual cycloolefin polymer;

[0011] The preparation method of the adsorbent comprises:

[0012] S1. Add the molecular sieve without removing the template agent to n-hexane, add trimethylchlorosilane dropwise, ultrasonicate, filter and dry, add the product to anhydrous ethanol, condense and reflux, wash and dry to obtain a modified molecular sieve;

[0013] S2. Add 3-mercaptopropyltrimethoxysilane and tannic acid to an acetate buffer solution and stir to prepare a solution;

[0014] S3. Add the modified molecular sieve to the solution in S2, heat to reflux, wash, and dry to obtain the target adsorbent.

[0015] Furthermore, in step (1), the main catalyst is any one of a catalyst containing molybdenum, a catalyst containing tungsten or a catalyst containing ruthenium; the co-catalyst is any one of a co-catalyst containing aluminum, magnesium or zinc; and the molar ratio of the main catalyst to the co-catalyst is 1:40-60.

[0016] Furthermore, in step (2), the cycloolefin monomer solution is obtained by adding tetracyclododecene and norbornene monomers in a molar ratio of 1:0.5-2 to cyclohexane, and the molar volume of norbornene monomers to cyclohexane is 0.5-2:1.5 mol / L; the ring-opening polymerization reaction is carried out at 60-80°C for 2-3 hours; the ring-opening polymerization reaction is terminated by adding a chain terminator to complete the ring-opening polymerization reaction; the hydrogenation reaction is carried out by adding a hydrogenation catalyst to the reactor and reacting at 180-200°C and 6-10 MPa for 2-4 hours.

[0017] Furthermore, in step S1 of the adsorbent preparation method, the molecular sieve from which the template is not removed is SBA-15 molecular sieve or MCM-41 molecular sieve.

[0018] Furthermore, in step S1 of the adsorbent preparation method, the solid-liquid ratio of the molecular sieve from which the template has not been removed to n-hexane is 1:8-12 g / mL; the amount of trimethylchlorosilane added is 5%-8% of the mass of the molecular sieve; and the ultrasonic treatment is carried out at 250-300W and 20-25°C for 40-60min.

[0019] Furthermore, in step S1 of the adsorbent preparation method, the solid-liquid ratio of the product to anhydrous ethanol is 1:100-200 g / mL; the reflux temperature is 70-80° C., and the reflux time is 10-12 h.

[0020] Furthermore, in step S2 of the adsorbent preparation method, the volume ratio of the 3-mercaptopropyltrimethoxysilane to the acetate buffer is 1:40-50; the solid-liquid ratio of the tannic acid to the acetate buffer is 1:20-30 g / mL; and the pH of the acetate buffer is 4.8-5.2.

[0021] Furthermore, in step S3 of the adsorbent preparation method, the solid-liquid ratio of the modified molecular sieve to the solution is 1:10-20 g / mL; the heating reflux temperature is 80-85° C., and the time is 2.5-3.5 h.

[0022] A low-metal residual cycloolefin polymer is prepared by any of the above preparation methods.

[0023] Application of a low-metal residual cycloolefin polymer in the field of medical packaging materials.

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

[0025] 1. In the post-processing process of the homogeneous process for preparing cycloolefin polymers, the present invention introduces the specific adsorbent prepared by the present invention to achieve deep removal of catalyst metals. The prepared low-metal residual cycloolefin polymer can meet the metal content requirements of medical packaging materials. At the same time, the deep removal of catalyst metal residues does not affect the structure and properties of the cycloolefin polymer itself, and has good application prospects.

[0026] 2. The adsorbent of the present invention is to reduce the adsorption of polar molecules by grafting hydrophobic groups on the surface of the molecular sieve, reduce the adhesion of subsequent high-viscosity cycloolefin polymer solutions, and preferentially capture catalyst metal impurities. The present invention removes the internal template of the molecular sieve pores by anhydrous ethanol, grafts thiol groups in the molecular sieve pores by 3-mercaptopropyltrimethoxysilane, and grafts phenolic hydroxyl groups in the molecular sieve pores by tannic acid. The introduction of thiol and phenolic hydroxyl groups increases the polar sites inside the molecular sieve pores, providing dual capture sites, which can stably and efficiently chelate the metal catalyst residues in the cycloolefin polymer solution, and uniformly fix the catalyst metal components in the pores of the molecular sieve through the confinement effect, thereby achieving the purpose of deep removal of catalyst metal components and purification of cycloolefin polymers. In addition, the modified molecular sieve of the present invention has a large specific surface area, high mechanical strength and high stability, is not easy to break and dissolve, can avoid the introduction of secondary impurity pollution, and can obtain low-metal residual cycloolefin polymers. DETAILED DESCRIPTION

[0027] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0028] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0029] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0030] The main catalyst of the present invention is a catalyst containing tungsten element, which is selected from one or more of tungsten chloride, tungsten oxychloride and tungsten.

[0031] The main catalyst is a catalyst containing molybdenum element, which is selected from one or more of molybdenum chloride, molybdenum oxide, molybdenum oxychloride, molybdenum carbide, molybdenum, and ammonium molybdate.

[0032] The main catalyst is a catalyst containing ruthenium element, which is selected from any one or more of GrubbsI, GrubbsII or GrubbsIII.

[0033] The co-catalyst of the present invention is one or more organic aluminum compounds such as triisobutylaluminum, triethylaluminum, tripropylaluminum, tri-n-butylaluminum, etc.

[0034] Example 1

[0035] A method for preparing a low-metal residual cycloolefin polymer, comprising the following steps:

[0036] (1) In a dry Schlenk flask that had been replaced with nitrogen three times, add 5×10 -4 mol tungsten chloride (primary catalyst), dissolved in 50 mL cyclohexane, and added 2.5 × 10 -2 mol triisobutylaluminum (co-catalyst) was activated for 30 min to obtain a catalyst solution;

[0037] (2) The catalyst solution was added to a reactor containing 1.0 mol of tetracyclododecene, 1.0 mol of norbornene, and 1.5 L of cyclohexane. The reaction was carried out at 60°C under a nitrogen atmosphere for 2 h. A chain terminator (0.15 mol of ethyl vinyl ether) was added to complete the ring-opening polymerization reaction. After the reaction was completed, a hydrogenation catalyst (5 × 10 -3 mol palladium / carbon catalyst), adjusting the temperature to 180° C., reacting for 2 h under a 6 MPa hydrogen atmosphere to obtain a cycloolefin polymer solution; (3) adding an adsorbent to the cycloolefin polymer solution, separating, and filtering to obtain the target low-metal residual cycloolefin polymer;

[0038] Preparation method of the above adsorbent:

[0039] S1, according to the solid-liquid ratio of 1:8g / mL, the SBA-15 molecular sieve without the template agent was added to n-hexane, and trimethylchlorosilane was added dropwise. The amount of trimethylchlorosilane added was 5% of the mass of the SBA-15 molecular sieve without the template agent. Ultrasonic treatment was performed at 250W and 20°C for 40min, filtered, washed, and dried to obtain a product. According to the solid-liquid ratio of 1:100g / mL, the product was added to anhydrous ethanol, condensed and refluxed at 70°C for 10h, fully washed, and dried to obtain a modified molecular sieve;

[0040] S2. Add 3-mercaptopropyltrimethoxysilane and tannic acid to an acetate buffer solution having a pH of 5.0±0.2 and stir, wherein the volume ratio of 3-mercaptopropyltrimethoxysilane to the acetate buffer solution is 1:40, and the solid-liquid ratio of tannic acid to the acetate buffer solution is 1:20 g / mL to prepare a solution;

[0041] S3. Add the modified molecular sieve to the solution in S2 at a solid-liquid ratio of 1:10 g / mL, heat and reflux at 80° C. for 2.5 h, wash, and dry to obtain the target adsorbent.

[0042] Example 2

[0043] Based on Example 1, tungsten chloride is replaced by molybdenum chloride.

[0044] Example 3

[0045] Based on Example 1, tungsten chloride was replaced by Grubbs I.

[0046] Example 4

[0047] A method for preparing a low-metal residual cycloolefin polymer, comprising the following steps:

[0048] (1) In a dry Schlenk flask that had been replaced with nitrogen three times, add 5×10 -4 mol tungsten chloride (primary catalyst), dissolved in 50 mL cyclohexane, and added 2.0×10 -2 mol triisobutylaluminum (co-catalyst) was activated for 30 min to obtain a catalyst solution;

[0049] (2) The catalyst solution was added to a reactor containing 1.0 mol of tetracyclododecene, 1.0 mol of norbornene, and 1.5 L of cyclohexane. The reaction was carried out at 80°C under a nitrogen atmosphere for 3 h. A chain terminator (0.15 mol of ethyl vinyl ether) was added to complete the ring-opening polymerization reaction. After the reaction was completed, a hydrogenation catalyst (5 × 10 -3 mol palladium / carbon catalyst), the temperature was adjusted to 200° C., and the reaction was carried out under a 10 MPa hydrogen atmosphere for 4 h to obtain a cycloolefin polymer solution;

[0050] (3) adding an adsorbent to the cycloolefin polymer solution, separating, and filtering to obtain the target low-metal residual cycloolefin polymer;

[0051] Preparation method of the above adsorbent:

[0052] S1, according to the solid-liquid ratio of 1:12g / mL, the MCM-41 molecular sieve without the template agent was added to n-hexane, and trimethylchlorosilane was added dropwise. The amount of trimethylchlorosilane added was 8% of the mass of the MCM-41 molecular sieve without the template agent. Ultrasonic treatment was performed at 300W and 25°C for 60min, filtered, washed, and dried to obtain a product. According to the solid-liquid ratio of 1:200g / mL, the product was added to anhydrous ethanol, condensed and refluxed at 80°C for 12h, fully washed, and dried to obtain a modified molecular sieve;

[0053] S2. Add 3-mercaptopropyltrimethoxysilane and tannic acid to an acetate buffer solution having a pH of 5.0±0.2 and stir, wherein the volume ratio of 3-mercaptopropyltrimethoxysilane to the acetate buffer solution is 1:50, and the solid-liquid ratio of tannic acid to the acetate buffer solution is 1:30 g / mL to prepare a solution;

[0054] S3. Add the modified molecular sieve to the solution in S2 at a solid-liquid ratio of 1:20 g / mL, heat and reflux at 85° C. for 3.5 h, wash, and dry to obtain the target adsorbent.

[0055] Example 5

[0056] Based on Example 4, tungsten chloride is replaced by molybdenum chloride.

[0057] Example 6

[0058] Based on Example 4, tungsten chloride was replaced by Grubbs I.

[0059] Example 7

[0060] A method for preparing a low-metal residual cycloolefin polymer, comprising the following steps:

[0061] (1) In a dry Schlenk flask that had been replaced with nitrogen three times, add 5×10 -4 mol tungsten chloride (primary catalyst), dissolved in 50 mL cyclohexane, and added 3.0×10 -2 mol triisobutylaluminum (co-catalyst) was activated for 30 min to obtain a catalyst solution;

[0062] (2) The catalyst solution was added to a reactor containing 1.0 mol of tetracyclododecene, 1.0 mol of norbornene, and 1.5 L of cyclohexane. The reaction was carried out at 70°C under a nitrogen atmosphere for 2.5 h. A chain terminator (0.15 mol of ethyl vinyl ether) was added to complete the ring-opening polymerization reaction. After the reaction was completed, a hydrogenation catalyst (5 × 10 -3 mol palladium / carbon catalyst), the temperature was adjusted to 190° C., and the reaction was carried out for 4 h under a hydrogen atmosphere of 8 MPa to obtain a cycloolefin polymer solution;

[0063] (3) adding an adsorbent to the cycloolefin polymer solution, separating, and filtering to obtain the target low-metal residual cycloolefin polymer;

[0064] Preparation method of the above adsorbent:

[0065] S1, according to the solid-liquid ratio of 1:10g / mL, the MCM-41 molecular sieve without the template agent was added to n-hexane, and trimethylchlorosilane was added dropwise. The amount of trimethylchlorosilane added was 6% of the mass of the MCM-41 molecular sieve without the template agent. Ultrasonic treatment was performed at 280W and 23°C for 50min, filtered, washed, and dried to obtain a product. According to the solid-liquid ratio of 1:150g / mL, the product was added to anhydrous ethanol, condensed and refluxed at 75°C for 11h, fully washed, and dried to obtain a modified molecular sieve;

[0066] S2. Add 3-mercaptopropyltrimethoxysilane and tannic acid to an acetate buffer solution having a pH of 5.0±0.2 and stir, wherein the volume ratio of 3-mercaptopropyltrimethoxysilane to the acetate buffer solution is 1:45, and the solid-liquid ratio of tannic acid to the acetate buffer solution is 1:25 g / mL to prepare a solution;

[0067] S3. Add the modified molecular sieve to the solution in S2 at a solid-liquid ratio of 1:15 g / mL, heat under reflux at 83° C. for 3 h, wash, and dry to obtain the target adsorbent.

[0068] Example 8

[0069] Based on Example 7, tungsten chloride is replaced by molybdenum chloride.

[0070] Example 9

[0071] Based on Example 7, tungsten chloride was replaced by Grubbs I.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that trimethylsilyl chloride is not used in the preparation of the adsorbent, and the other steps are the same as those in Example 1;

[0074] Preparation method of the adsorbent of this comparative example:

[0075] S1. Add the unremoved template SBA-15 molecular sieve to anhydrous ethanol at a solid-liquid ratio of 1:100 g / mL, reflux under condensation at 70°C for 10 h, wash thoroughly, and dry to obtain a molecular sieve;

[0076] S2. Add 3-mercaptopropyltrimethoxysilane and tannic acid to an acetate buffer solution having a pH of 5.0±0.2 and stir, wherein the volume ratio of 3-mercaptopropyltrimethoxysilane to the acetate buffer solution is 1:40, and the solid-liquid ratio of tannic acid to the acetate buffer solution is 1:20 g / mL to prepare a solution;

[0077] S3. Add molecular sieves to the solution in S2 at a solid-liquid ratio of 1:10 g / mL, heat under reflux at 80°C for 2.5 h, wash, and dry to obtain an adsorbent.

[0078] Comparative Example 2

[0079] The difference between this comparative example and Example 2 is that 3-mercaptopropyltrimethoxysilane is not used in the preparation of the adsorbent, and the other steps are the same as those in Example 1;

[0080] Preparation method of the adsorbent of this comparative example:

[0081] S1, according to the solid-liquid ratio of 1:8g / mL, the SBA-15 molecular sieve without the template agent was added to n-hexane, and trimethylchlorosilane was added dropwise. The amount of trimethylchlorosilane added was 5% of the mass of the SBA-15 molecular sieve without the template agent. Ultrasonic treatment was performed at 250W and 20°C for 40min, filtered, washed, and dried to obtain a product. According to the solid-liquid ratio of 1:100g / mL, the product was added to anhydrous ethanol, condensed and refluxed at 70°C for 10h, fully washed, and dried to obtain a modified molecular sieve;

[0082] S2. Add tannic acid to an acetate buffer solution having a pH of 5.0±0.2 and stir, wherein the solid-to-liquid ratio of tannic acid to acetate buffer solution is 1:20 g / mL to prepare a solution;

[0083] S3. Add the modified molecular sieve to the solution in S2 at a solid-liquid ratio of 1:10 g / mL, heat and reflux at 80° C. for 2.5 h, wash, and dry to obtain an adsorbent.

[0084] Comparative Example 3

[0085] This comparative example differs from Example 3 in that tannic acid is not used in the preparation of the adsorbent, and the other steps are the same as in Example 1.

[0086] Preparation method of the adsorbent of this comparative example:

[0087] S1, according to the solid-liquid ratio of 1:8g / mL, the SBA-15 molecular sieve without the template agent was added to n-hexane, and trimethylchlorosilane was added dropwise. The amount of trimethylchlorosilane added was 5% of the mass of the SBA-15 molecular sieve without the template agent. Ultrasonic treatment was performed at 250W and 20°C for 40min, filtered, washed, and dried to obtain a product. According to the solid-liquid ratio of 1:100g / mL, the product was added to anhydrous ethanol, condensed and refluxed at 70°C for 10h, fully washed, and dried to obtain a modified molecular sieve;

[0088] S2. Add 3-mercaptopropyltrimethoxysilane to an acetate buffer solution having a pH of 5.0±0.2 and stir, wherein the volume ratio of 3-mercaptopropyltrimethoxysilane to the acetate buffer solution is 1:40, to prepare a solution;

[0089] S3. Add the modified molecular sieve to the solution in S2 at a solid-liquid ratio of 1:10 g / mL, heat and reflux at 80° C. for 2.5 h, wash, and dry to obtain an adsorbent.

[0090] Test Example 1

[0091] The metal content of the cycloolefin polymers treated with the adsorbents of Examples 1-9 and Comparative Examples 1-3 was analyzed by ICP detection. The results are shown in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] As shown in Table 1, the adsorbent prepared by the present invention can deeply remove residual metal catalysts from cycloolefin polymers, purifying the cycloolefin polymers and enabling their application in pharmaceutical packaging materials, thereby improving safety. Comparative Examples 1-3 were unable to deeply remove the metal components from the catalysts, resulting in residual amounts that did not meet the requirements for pharmaceutical packaging materials and exhibiting poor safety.

[0096] Test Example 2

[0097] The parameters of the cycloolefin polymers prepared in Example 1, Example 4, and Example 7 before and after the catalyst metal was removed by the adsorbent were tested, including weight average molecular weight (Mw), molecular weight distribution (PDI), and transmittance. The results are shown in Table 2.

[0098] The weight average molecular weight (Mw) and molecular weight distribution (PDI) are measured by high temperature gel permeation chromatography; and the transmittance is measured by a spectrophotometer.

[0099] Table 2

[0100]

[0101] Combining Table 1 and Table 2, it can be seen that the adsorbent of the present invention deeply removes residual catalyst metals without affecting the property parameters of the cycloolefin polymer itself.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a low-metal residual cycloolefin polymer, characterized in that: The specific steps include: (1) mixing the main catalyst, the co-catalyst and the organic solution to obtain a catalyst solution; (2) injecting the cycloolefin monomer solution and the catalyst solution into a reactor to carry out a ring-opening polymerization reaction, and after the ring-opening polymerization reaction is completed, carrying out a hydrogenation reaction to obtain a cycloolefin polymer solution; (3) adding an adsorbent to the cycloolefin polymer solution and separating the solution to obtain the target low-metal residual cycloolefin polymer; The preparation method of the adsorbent comprises: S1. Add the molecular sieve without removing the template agent to n-hexane, add trimethylchlorosilane dropwise, ultrasonicate, filter and dry, add the product to anhydrous ethanol, condense and reflux, wash and dry to obtain a modified molecular sieve; S2. Add 3-mercaptopropyltrimethoxysilane and tannic acid to an acetate buffer solution and stir to prepare a solution; S3. Add the modified molecular sieve to the solution in S2, heat to reflux, wash, and dry to obtain the target adsorbent.

2. The method for preparing a low-metal residual cycloolefin polymer according to claim 1, wherein: In step (1), the main catalyst is any one of a catalyst containing molybdenum, a catalyst containing tungsten or a catalyst containing ruthenium; the co-catalyst is any one of a co-catalyst containing aluminum, magnesium or zinc; and the molar ratio of the main catalyst to the co-catalyst is 1:40-60.

3. The method for preparing a low-metal residual cycloolefin polymer according to claim 1, wherein: In step (2), the cycloolefin monomer solution is obtained by adding tetracyclododecene and norbornene monomers in a molar ratio of 1:0.5-2 to cyclohexane, and the molar volume of norbornene monomers to cyclohexane is 0.5-2:1.5 mol / L; the ring-opening polymerization reaction is carried out at 60-80°C for 2-3 hours; the ring-opening polymerization reaction is terminated by adding a chain terminator to complete the ring-opening polymerization reaction; the hydrogenation reaction is carried out by adding a hydrogenation catalyst to the reactor and reacting at 180-200°C and 6-10 MPa for 2-4 hours.

4. The method for preparing a low-metal residual cycloolefin polymer according to claim 1, wherein: In step S1 of the adsorbent preparation method, the molecular sieve from which the template is not removed is SBA-15 molecular sieve or MCM-41 molecular sieve.

5. The method for preparing a low-metal residual cycloolefin polymer according to claim 1, wherein: In step S1 of the adsorbent preparation method, the solid-liquid ratio of the molecular sieve from which the template has not been removed to n-hexane is 1:8-12 g / mL; the amount of trimethylchlorosilane added is 5%-8% of the mass of the molecular sieve; and the ultrasonic treatment is carried out at 250-300W and 20-25°C for 40-60min.

6. The method for preparing a low-metal residual cycloolefin polymer according to claim 1, wherein: In step S1 of the adsorbent preparation method, the solid-liquid ratio of the product to anhydrous ethanol is 1:100-200 g / mL; the reflux temperature is 70-80° C., and the reflux time is 10-12 h.

7. The method for preparing a low-metal residual cycloolefin polymer according to claim 1, wherein: In step S2 of the adsorbent preparation method, the volume ratio of the 3-mercaptopropyltrimethoxysilane to the acetate buffer is 1:40-50; the solid-liquid ratio of the tannic acid to the acetate buffer is 1:20-30 g / mL; and the pH of the acetate buffer is 4.8-5.

2.

8. The method for preparing a low-metal residual cycloolefin polymer according to claim 1, wherein: In step S3 of the adsorbent preparation method, the solid-liquid ratio of the modified molecular sieve to the solution is 1:10-20 g / mL; the heating reflux temperature is 80-85° C., and the time is 2.5-3.5 h.

9. A low metal residual cycloolefin polymer, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the low metal residue cycloolefin polymer according to claim 9 in the field of medical packaging materials.

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