Method for recycling cycloolefin polymer

Abstract

The invention belongs to the technical field of polymer recovery, and relates to a method for recycling a cycloolefin polymer, which comprises the following steps of: providing a first cycloolefin polymer obtained by copolymerizing a cycloolefin monomer and a monomer containing an olefin-ether bond in a molar ratio of (1: 0.05)-(1: 0.2); the first cycloolefin polymer is put into an acidic degradation solution to be degraded, then weak base is added for neutralization, concentration and precipitation are conducted, a second cycloolefin polymer is obtained, and the chain length of the second cycloolefin polymer is shorter than that of the first cycloolefin polymer; and hydrogenating the second cycloolefin polymer to obtain the saturated cycloolefin polymer. According to the invention, the short-chain polymer obtained by degradation is prepared into a saturated short-chain polymer without double bonds, and the thermoplastic polymer which is stable in property, good in thermoformability and easy to process is obtained, so that the performance of the recycled material is improved, and the application range of the recycled material is expanded.

Description

Technical Field

[0001] This invention belongs to the field of polymer recycling technology, and particularly relates to a method for recycling and reusing cyclic olefin polymers. Background Technology

[0002] Polycyclic olefins (PROPs), produced from cyclic olefins via ring-opening metathesis polymerization, are a class of high-performance thermosetting materials with excellent thermal and mechanical properties, as well as good chemical stability, making them suitable for various fields such as medical devices and automotive manufacturing. However, like most thermosetting materials, these products cannot be further processed after molding, making recycling difficult and resulting in resource waste. According to relevant literature, there are three main methods for recycling thermosetting materials: mechanical crushing, which involves pulverizing the thermosetting material to be recycled into small particles for use as fillers; heat recovery, which involves burning the resin matrix, which easily produces harmful gases; and chemical recovery, which uses chemical reagents to convert the polymer into smaller molecules or raw materials, and this method has greater application prospects.

[0003] Pure polycyclic olefins cannot be converted into small molecules or cyclic olefin monomers by chemical reagents. Other degradable substances need to be incorporated into the polyolefin chain segments to degrade them into small molecule polymers. A related technology, US Patent No. 20240239958A1, describes a degradable polymer obtained by copolymerizing compounds containing enyl ether bonds with various norbornene and their derivatives. The polymer chain contains enol ether structures, and the mechanical properties of the polymer are comparable to those of pure cyclic olefin polymers.

[0004] Thermosetting polyolefins obtained through the aforementioned technologies typically yield short-chain polycyclic olefins with hemiacetal end groups after acid-catalyzed hydration degradation. The short-chain polyolefins obtained from this degradation have aldehyde or hydroxyl end groups, and the polymer chains still contain double bonds. This results in chemical instability, poor thermal stability, and poor oxidation resistance in the reprocessed products, limiting the application range of the degraded short-chain polyolefins. Therefore, obtaining a chemically stable degradable polymer while ensuring good mechanical properties and degradability is crucial for improving recycling efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a method for recycling and reusing cyclic olefin polymers to solve the above-mentioned problems. By converting the short-chain polymer obtained from degradation into a saturated short-chain polymer without double bonds, a thermoplastic polymer with stable properties, good thermoforming properties, and easy processing is obtained, thereby improving the performance of recycled materials and expanding the application range of recycled materials.

[0006] This invention proposes a method for recycling and reusing cyclic olefin polymers, comprising the following steps:

[0007] Step S1: Provide a first cyclic olefin polymer obtained by copolymerization of a cyclic olefin monomer and a monomer containing an olefin ether bond, wherein the molar ratio of the cyclic olefin monomer to the monomer containing an olefin ether bond is 1:0.05 to 1:0.2.

[0008] Step S2: The first cyclic olefin polymer is placed in an acidic degradation solution for degradation, and then a weak base is added for neutralization and concentration to precipitate the second cyclic olefin polymer. The chain length of the second cyclic olefin polymer is shorter than that of the first cyclic olefin polymer.

[0009] Step S3: Hydrogenate the second cyclic olefin polymer to obtain a saturated cyclic olefin polymer.

[0010] In one or more embodiments, step S3 includes:

[0011] Step S301: Disperse or dissolve the second cyclic olefin polymer in the first solvent;

[0012] Step S302: Add reducing agent to obtain the solution to be hydrogenated;

[0013] Step S303: The solution to be hydrogenated is subjected to a hydrogenation reaction at a hydrogenation temperature to obtain a saturated cyclic olefin polymer.

[0014] In one or more embodiments, the first solvent is o-xylene, or a mixture of o-xylene and dimethylacetamide.

[0015] In one or more embodiments, the reducing agent is hydrogen, a mixture of nitrogen and hydrogen, or a mixture of hydrogen and argon.

[0016] In one or more embodiments, the hydrogenation temperature is 80–135°C, and the hydrogenation reaction time is 4–48 h.

[0017] In one or more embodiments, the first solvent is methanol, tetrahydrofuran, toluene, or dimethyl sulfoxide.

[0018] In one or more embodiments, the reducing agent is p-toluenesulfonyl hydrazine, dipotassium azobiscarboxylate, or hydrazine hydrate.

[0019] In one or more embodiments, the hydrogenation temperature is 60–140°C, and the hydrogenation reaction time is 4–48 h.

[0020] In one or more embodiments, step S302 includes: dispersing or dissolving the second cyclic olefin polymer in a first solvent, adding ethanolamine to prepare an ethanolamine solution, and then adding the reducing agent to the ethanolamine solution to obtain a solution to be hydrogenated.

[0021] In one or more embodiments, step S303 includes: heating the solution to be hydrogenated to the hydrogenation temperature to perform a hydrogenation reaction to obtain a hydrogenation reaction solution; cooling the hydrogenation reaction solution to room temperature and adding a poor solvent to precipitate a saturated cyclic olefin polymer; filtering and drying the saturated cyclic olefin polymer.

[0022] In one or more embodiments, the saturated cyclic olefin polymer in step S303 has a molecular weight of 2500-4500 g / mol.

[0023] In one or more embodiments, the first cyclic olefin polymer is prepared by a method comprising the following steps:

[0024] Mix cyclic olefin monomers with monomers containing olefin ether bonds;

[0025] Add a ring-opening metathesis polymerization catalyst dissolved in a second solvent;

[0026] After heating to the polymerization temperature, ring-opening metathesis polymerization is carried out to obtain the first cyclic olefin polymer.

[0027] In one or more embodiments, the monomer containing the ether bond is 2,3-dihydrofuran.

[0028] In one or more embodiments, the cyclic olefin monomer is selected from one or more of dicyclopentadiene, norbornene, and norbornene derivatives, wherein the norbornene derivative is selected from one or more of 5-ethylidene-2-norbornene, 5-norbornene-2,3-dicarboxylic anhydride, 3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, and 5-norbornene-2,3-dicarboximide.

[0029] In one or more embodiments, the ring-opening metathesis polymerization catalyst includes at least one of Grubbs first-generation catalyst, Grubbs second-generation catalyst, Grubbs third-generation catalyst, and Hoveyda Grubbs catalyst.

[0030] In one or more embodiments, the second solvent is tetrahydrofuran, dichloromethane, diphenyl ether, dichloroethane, toluene, xylene, or methyl fluoroether.

[0031] In one or more embodiments, the amount of the ring-opening metathesis polymerization catalyst relative to the cyclic olefin monomer is 0.1 ppm to 200 ppm.

[0032] In one or more embodiments, the polymerization temperature is 40°C to 140°C, and the ring-opening metathesis polymerization time is 0.5h to 24h.

[0033] In one or more embodiments, step S2 includes:

[0034] The first cyclic olefin polymer is placed in an acidic degradation solution for degradation until the first cyclic olefin polymer is completely dissolved to obtain a first solution;

[0035] Add a weak base to the first solution until no more bubbles are produced when the weak base is added to the first solution, to obtain a second solution;

[0036] The second solution is concentrated until a solid precipitates out. Methanol is then added, and the precipitate yields a second cyclic olefin polymer.

[0037] In one or more embodiments, the acidic degradation solution is a solution obtained by dissolving hydrochloric acid in tetrahydrofuran, and the concentration of hydrochloric acid in the acidic degradation solution is 0.5 mol / L to 2 mol / L.

[0038] In one or more embodiments, the weak base is sodium bicarbonate.

[0039] Compared with the prior art, the beneficial effects of the method for recycling and reusing cyclic olefin polymers of the present invention are as follows:

[0040] 1) This invention degrades biodegradable cyclic olefin polymers and hydrogenates the degraded short-chain polymers using a reducing agent to obtain a class of thermoplastic polymer materials with excellent rigidity and oxidation resistance, stable chemical properties, good fluidity in the molten state, high hardness and low moisture absorption at room temperature, good formability and thermoplasticity, suitable for extrusion, injection molding, calendering, blow molding and thermoforming. As an upgraded recycling material, it has outstanding performance advantages and can be used in injection molding, 3D printing and other processing methods, with a wide range of applications.

[0041] 2) This invention provides a direction for the recycling and reuse of thermosetting materials and is of great significance for the recycling and reuse of thermosetting polymers.

[0042] 3) This invention uses different reducing agents to hydrogenate short-chain polymers, and the hydrogenation rate can reach more than 99%. Attached Figure Description

[0043] Figure 1 This is a schematic flowchart of a method for recycling and reusing cyclic olefin polymers according to an embodiment of the present invention;

[0044] Figure 2 The chemical reaction structure of a norbornene derivative according to an embodiment of the present invention is shown below.

[0045] Figure 3 The image shows a comparison of the infrared spectra of the second cyclic olefin polymer and the saturated cyclic olefin polymer in Example 1.

[0046] Figure 4 The image shows a comparison of the proton NMR spectra of the second cyclic olefin polymer and the saturated cyclic olefin polymer in Example 1.

[0047] Figure 5 This is a gel permeation chromatogram of the saturated cyclic olefin polymer in Example 1;

[0048] Figure 6 This is a heat flow curve of the saturated cyclic olefin polymer in Example 1. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention more readily apparent, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described are merely illustrative and are not intended to limit the scope of this invention.

[0050] This invention proposes a method for recycling and reusing cyclic olefin polymers, see [link to relevant documentation]. Figure 1 It includes the following steps:

[0051] Step S1, Polymerization: Copolymerize the cyclic olefin monomer with a monomer containing an olefin ether bond to obtain a first cyclic olefin polymer. The monomer containing the olefin ether bond is a biodegradable monomer, and the first cyclic olefin polymer is a biodegradable cyclic olefin polymer; or directly use the first cyclic olefin polymer obtained by copolymerizing the cyclic olefin monomer with a monomer containing an olefin ether bond.

[0052] Step S2, Degradation: The first cyclic olefin polymer is placed in an acidic degradation solution for degradation, and then a weak base is added for neutralization and concentration to precipitate the second cyclic olefin polymer, which has a shorter chain length than the first cyclic olefin polymer.

[0053] Step S3, hydrogenation reduction: The second cyclic olefin polymer is hydrogenated to obtain a saturated cyclic olefin polymer.

[0054] The first cyclic olefin polymer of some embodiments of the present invention is prepared by a method comprising the following steps:

[0055] Mix cyclic olefin monomers with monomers containing olefin ether bonds;

[0056] Add a ring-opening metathesis polymerization catalyst dissolved in a second solvent;

[0057] After heating to the polymerization temperature, ring-opening metathesis polymerization is carried out to obtain a first cyclic olefin polymer, which is a solidified block.

[0058] The preferred molar ratio of cyclic olefin monomer to monomer containing olefin ether bond is 1:0.05 to 1:0.2; the amount of ring-opening metathesis polymerization catalyst relative to cyclic olefin monomer is 0.1 ppm to 200 ppm; the polymerization temperature is 40℃ to 140℃; and the ring-opening metathesis polymerization time is 0.5 h to 24 h.

[0059] In this invention, the alkenyl ether bond refers to "-OC = C-". The monomer containing the alkenyl ether bond can be a heterocyclic olefin, which has 4-6 (e.g., 5) carbon atoms, 1 carbon-carbon double bond, and 1 oxygen atom bonded to the carbon-carbon double bond. The monomer containing the alkenyl ether bond is preferably 2,3-dihydrofuran. The cyclic olefin monomer is selected from one or more of dicyclopentadiene, norbornene, and norbornene derivatives. The norbornene derivative is selected from one or more of 5-ethylidene-2-norbornene, 5-norbornene-2,3-dicarboxylic anhydride, 3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, and 5-norbornene-2,3-dicarboximide. The ring-opening metathesis polymerization catalyst includes at least one of Grubbs first-generation catalysts, Grubbs second-generation catalysts, Grubbs third-generation catalysts, and Hoveydagrubbs catalysts. The second solvent is tetrahydrofuran, dichloromethane, diphenyl ether, dichloroethane, toluene, xylene, or methyl fluoroether.

[0060] Step S2 of some embodiments of the present invention, which involves placing the first cyclic olefin polymer in an acidic degradation solution to degrade it and obtain the second cyclic olefin polymer, includes:

[0061] The first cyclic olefin polymer is placed in an acidic degradation solution for degradation until all the degradable first cyclic olefin polymer solidified blocks dissolve and disappear, thus obtaining the first solution. The degradation time is generally 1-100 hours.

[0062] Add a weak base to the first solution until no more bubbles are produced when a weak base is added to the first solution, to obtain the second solution. At this point, the second solution is weakly alkaline.

[0063] The second solution is concentrated until a small amount of solid precipitates out. Methanol is then added, and the precipitate yields the second cyclic olefin polymer, which is the short-chain cyclic olefin polymer to be hydrogenated.

[0064] The acidic degradation solution is a solution obtained by dissolving hydrochloric acid in tetrahydrofuran (i.e., hydrochloric acid / THF degradation solution). The concentration of hydrochloric acid in the acidic degradation solution is 0.5 mol / L to 2 mol / L, that is, the amount of hydrochloric acid in 1 L of tetrahydrofuran is 0.5 to 2 mol, and the volume ratio of 1 mol / L hydrochloric acid to tetrahydrofuran is 1:9. The weak base is sodium bicarbonate.

[0065] Step S3 of some embodiments of the present invention, the step of hydrogenating the second cyclic olefin polymer to obtain a saturated cyclic olefin polymer, includes:

[0066] Step S301: Disperse or dissolve the second cyclic olefin polymer in the first solvent;

[0067] Step S302: Add reducing agent to obtain the solution to be hydrogenated;

[0068] Step S303: The solution to be hydrogenated is subjected to a hydrogenation reaction at the hydrogenation temperature to obtain a saturated cyclic olefin polymer.

[0069] The hydrogenation reaction is carried out in a closed container equipped with a condenser to allow for continuous reflux during the hydrogenation process.

[0070] This invention mainly employs two methods for hydrogenating second-cyclic olefin polymers:

[0071] The first method uses hydrogen, a mixture of nitrogen and hydrogen, or a mixture of hydrogen and argon as a reducing agent. In this method, the solvent (first solvent) that disperses or dissolves the second cyclic olefin polymer is o-xylene, or a mixture of o-xylene and dimethylacetamide (o-xylene / DMAc 2 / 1 mixed solvent). The hydrogenation temperature is 80-135°C, and the hydrogenation reaction time is 4-48 hours. A hydrogenation catalyst, such as RuHCl(CO)(PPh3)3, is still required to accelerate the reaction rate.

[0072] The specific steps for hydrogenation in the first method include:

[0073] After dispersing or dissolving the second cyclic olefin polymer in the first solvent, a hydrogenation catalyst is added, and the temperature is raised to the hydrogenation temperature;

[0074] A gaseous reducing agent is introduced to obtain the solution to be hydrogenated;

[0075] The solution to be hydrogenated is subjected to a hydrogenation reaction at a hydrogenation temperature to obtain a saturated cyclic olefin polymer;

[0076] Finally, the saturated cyclic olefin polymer is cleaned and dried.

[0077] The second method uses p-toluenesulfonyl hydrazine, dipotassium azobiscarboxylate, or hydrazine hydrate as a reducing agent. In this method, the molar ratio of the second cyclic olefin polymer to the reducing agent is approximately 1:6. The solvent for dispersing or dissolving the second cyclic olefin polymer (the first solvent) is methanol, tetrahydrofuran, toluene, or dimethyl sulfoxide. The hydrogenation temperature is 60–140°C, and the hydrogenation reaction time is 4–48 h.

[0078] The specific steps for hydrogenation using the second method include:

[0079] After dispersing or dissolving the second cyclic olefin polymer in the first solvent, ethanolamine is added to provide an alkaline environment, thus preparing a 1.5M ethanolamine solution.

[0080] Add a reducing agent to the ethanolamine solution to obtain the solution to be hydrogenated;

[0081] The solution to be hydrogenated is heated to the hydrogenation temperature to carry out a hydrogenation reaction, resulting in a hydrogenation reaction solution.

[0082] After cooling the hydrogenation reaction solution to room temperature, a poor solvent was added, and saturated cyclic olefin polymers were precipitated.

[0083] Finally, the saturated cyclic olefin polymer is filtered, separated, and dried.

[0084] The unsuitable solvent can be methanol, etc., to induce the precipitation of saturated cyclic olefin polymers, thus aiding in separation and purification. Specifically, the upper layer of the hydrogenation reaction solution is liquid, and the lower layer is oily saturated cyclic olefin polymer. After adding the unsuitable solvent, the lower layer becomes solid, and some of the saturated cyclic olefin polymer dissolved in the first solvent will also precipitate out.

[0085] In summary, this invention first degrades the thermosetting cyclic olefin polymer obtained by ring-opening metathesis polymerization using acid catalysis, and then hydrogenates and reduces the degraded short-chain polymer to obtain a stable, easily recyclable, and widely applicable thermoplastic material. This provides a new direction for the recycling and reuse of thermosetting materials. Furthermore, the hydrogenation rate of the short-chain polymer can reach over 99% using different reducing agents, which also has significant value in terms of large-scale production and improving product quality stability.

[0086] The existing substances used in this invention, such as cyclic olefin monomers and 2,3-dihydrofuran, are well-known in the art and can be purchased commercially.

[0087] The method for recycling and reusing cyclic olefin polymers according to the present invention will be described in detail below through specific embodiments.

[0088] Example 1

[0089] Polymerization: Weigh 20 g (0.15 mol) of dicyclopentadiene into a test tube, then add 0.53 g (7.5 mmol, 5 mol%) of 2,3-dihydrofuran and mix thoroughly. Weigh 9.6 mg (75 ppm) of Grubbs second-generation catalyst, add 0.5 ml of dichloromethane to dissolve it, and then slowly add the catalyst solution to the mixture of dicyclopentadiene and 2,3-dihydrofuran, shaking vigorously until well mixed. Then place in a 100°C oven for 4 hours. After polymerization, remove the solidified block of the first cycloolefin polymer from the test tube for later use.

[0090] Degradation: First, prepare a 1 mol / L hydrochloric acid / tetrahydrofuran degradation solution: Add 500 ml of tetrahydrofuran to a 1000 ml three-necked flask, bubble with nitrogen for 1 hour to remove oxygen from the tetrahydrofuran, then add 42 ml of hydrochloric acid and stir well. Place the solidified block produced by polymerization into the prepared acidic degradation solution and let it stand for 18 hours for degradation. After degradation, the yellow solidified block disappears, and the solution turns black. Then, slowly add sodium bicarbonate solid, which reacts vigorously and releases a large number of bubbles. After adding sodium bicarbonate, no more bubbles are produced, filter with diatomaceous earth, concentrate the filtrate until a small amount of solid precipitates, add a large amount of methanol, stir vigorously, and a large amount of black solid precipitates, which is the second cyclic olefin polymer (the short-chain polymer to be hydrogenated). Then filter and dry the black solid.

[0091] Hydrogenation reduction: Weigh 1.3 g (0.01 mmol) of the second cyclic olefin polymer into a 250 mL three-necked flask, dissolve it in 100 mL of tetrahydrofuran, then add 9.3 g of ethanolamine to prepare a 1.5 M ethanolamine-tetrahydrofuran solution. Slowly add 11 g (0.059 mol) of p-toluenesulfonyl hydrazine, and reflux at 80 °C for 24 h. The black solution changes to a yellow suspension, separating into two layers: a white upper layer and a yellow lower layer. Cool to room temperature, add 30 mL of methanol to precipitate the polymer, filter, and dry to obtain a pale yellow solid, which is the hydrogenated saturated cyclic olefin polymer.

[0092] Performance Testing: The second cyclic olefin polymer and the saturated cyclic olefin polymer obtained in this embodiment were measured by proton nuclear magnetic resonance spectroscopy and infrared spectroscopy, respectively. The hydrogenation rate of the saturated cyclic olefin polymer obtained in this embodiment was greater than 99%. Gel permeation chromatography (GPC) was performed on the saturated cyclic olefin polymer obtained in this embodiment, and the molecular weight was determined to be 3077 g / mol with a molecular weight distribution of 1.51. Differential scanning calorimetry (DSC) was performed on the saturated cyclic olefin polymer obtained in this embodiment, and the glass transition temperature To of the saturated cyclic olefin polymer was determined. g The temperature is 95℃.

[0093] Example 2

[0094] Unlike Example 1, the amount of 2,3-dihydrofuran used in the polymerization step was 1.06 g (15 mmol, concentration 10 mol%). Performance tests were performed on the saturated cyclic olefin polymer obtained in this example: by nuclear magnetic resonance (NMR) spectroscopy and infrared spectroscopy, the hydrogenation rate of the saturated cyclic olefin polymer obtained in this example was greater than 99%; by GPC testing, the molecular weight of the saturated cyclic olefin polymer obtained in this example was 2988 g / mol, and the molecular weight distribution was 1.82; by DSC testing, the Tg of the saturated cyclic olefin polymer obtained in this example was... g The temperature is 85℃.

[0095] Example 3

[0096] Unlike Example 1, the amount of Grubbs' second-generation catalyst used in the polymerization step was 12.8 mg (100 ppm). Performance tests were performed on the saturated cyclic olefin polymer obtained in this example: hydrogenation rate was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight was 4235 g / mol and the molecular weight distribution was 1.54 as determined by GPC; and the Tg of the saturated cyclic olefin polymer obtained in this example was [not specified in the original text]. g It is 99℃.

[0097] Example 4

[0098] Unlike Example 1, the ring-opening metathesis polymerization catalyst used in this example was a third-generation Grubbs catalyst, at a dosage of 6.7 mg (50 ppm). Performance tests were performed on the saturated cyclic olefin polymer obtained in this example: hydrogenation rate was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight was 3379 g / mol and the molecular weight distribution was 1.63 as determined by GPC; and the Tg of the saturated cyclic olefin polymer obtained in this example was [not specified in the original text]. g It is 94℃.

[0099] Example 5

[0100] Unlike Example 1, the ring-opening metathesis polymerization in this example was carried out at a polymerization temperature of 120°C for 2 hours. Performance tests were performed on the saturated cyclic olefin polymer obtained in this example: Hydrogenation rate was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight was 3541 g / mol and the molecular weight distribution was 1.59 as determined by GPC; and the Tg of the saturated cyclic olefin polymer obtained in this example was [not specified in the original text]. g It is 96℃.

[0101] Example 6

[0102] Unlike Example 1, the concentration of hydrochloric acid in the acidic degradation solution used in the degradation process was 2 mol / L, and the degradation time was 48 h. Performance tests were performed on the saturated cyclic olefin polymer obtained in this example: Hydrogenation rate of the saturated cyclic olefin polymer obtained in this example was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight of the saturated cyclic olefin polymer obtained in this example was 3317 g / mol and the molecular weight distribution was 1.67 as determined by GPC; the Tg of the saturated cyclic olefin polymer obtained in this example was [not specified in the original text]. g The temperature is 95℃.

[0103] Example 7

[0104] Unlike Example 1, methanol was used as the first solvent for dispersing the second cyclic olefin polymer in the hydrogenation reduction step. The specific steps of the hydrogenation reduction were as follows: 1.3 g (0.01 mmol) of the second cyclic olefin polymer was weighed into a 250 ml three-necked flask, and 100 ml of methanol was added to disperse it. Then, 9.3 g of ethanolamine was added to prepare a 1.5 M ethanolamine-methanol solution. Next, 11 g (0.059 mol) of p-toluenesulfonyl hydrazine was slowly added, and the mixture was heated to 70 °C and refluxed for 24 h. The black suspension solution changed to a yellow suspension, and the layers separated into two parts: a white upper layer and a yellow lower layer. After cooling to room temperature, the mixture was filtered and dried to obtain a brownish-yellow saturated cyclic olefin polymer.

[0105] The performance of the saturated cyclic olefin polymer obtained in this embodiment was tested: Hydrogenation rate was greater than 80% as determined by 1H NMR and infrared spectroscopy; the molecular weight was 3755 g / mol and the molecular weight distribution was 1.34 as determined by GPC; and the Tg of the saturated cyclic olefin polymer obtained in this embodiment was [not specified in the original text]. g It is 91℃.

[0106] Example 8

[0107] Unlike Example 1, hydrazine hydrate was used as the reducing agent in the hydrogenation reduction step. The specific steps of the hydrogenation reduction were as follows: 1.3 g (0.01 mmol) of the second cyclic olefin polymer was weighed into a 250 ml three-necked flask, dissolved in 100 ml of tetrahydrofuran, followed by the addition of 9.3 g of ethanolamine to prepare a 1.5 M ethanolamine-tetrahydrofuran solution. Then, 3 g (0.060 mol) of hydrazine hydrate was slowly added, and the mixture was reacted at room temperature for 1 h, followed by reflux at 80 °C for 12 h. The black solution turned into a yellow suspension, with separate layers; the upper layer was white, and the lower layer was yellow. After cooling to room temperature, 30 ml of methanol was added to precipitate the polymer. The mixture was filtered and dried to obtain a brownish-yellow saturated cyclic olefin polymer.

[0108] The performance of the saturated cyclic olefin polymer obtained in this embodiment was tested: Hydrogenation rate was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight was 3293 g / mol and the molecular weight distribution was 1.53 as determined by GPC; and the Tg of the saturated cyclic olefin polymer obtained in this embodiment was [not specified in the original text]. g The temperature is 95℃.

[0109] Example 9

[0110] Unlike Example 1, the reducing agent used in the hydrogenation reduction step is dipotassium azodiacarboxylate. The specific steps of the hydrogenation reduction are as follows: 1.3 g (0.01 mmol) of the second cyclic olefin polymer is weighed into a 250 ml three-necked flask, dissolved in 20 ml of dimethyl sulfoxide, and then 7 g (0.060 mol) of dipotassium azodiacarboxylate is slowly added. The reaction is carried out at room temperature for 1 h, followed by heating to 100 °C and reacting for 20 h. The black solution changes to a yellow suspension, with two layers: a white upper layer and a yellow lower layer. After cooling to room temperature, 30 ml of methanol is added to precipitate the polymer. The mixture is filtered, dried, and a brownish-yellow saturated cyclic olefin polymer is obtained.

[0111] The performance of the saturated cyclic olefin polymer obtained in this embodiment was tested: Hydrogenation rate was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight was 3351 g / mol and the molecular weight distribution was 1.41 as determined by GPC; and the Tg of the saturated cyclic olefin polymer obtained in this embodiment was [not specified in the original text]. g It is 96℃.

[0112] Example 10

[0113] Unlike Example 1, the cyclic olefin monomer used in the polymerization was replaced with norbornene instead of dicyclopentadiene. The specific polymerization steps were as follows: 10 g (0.11 mol) of norbornene was weighed into a test tube, and 0.74 g (11 mmol, 10 mol%) of 2,3-dihydrofuran was added and mixed thoroughly. 9 mg (100 ppm) of Grubbs' second-generation catalyst was weighed and dissolved in 0.5 ml of dichloromethane. This catalyst solution was slowly added to the mixture of norbornene and 2,3-dihydrofuran, and the mixture was vigorously shaken and mixed thoroughly. The mixture was then placed in an oven at 80°C for 4 hours. After polymerization, the solidified block of the first cyclic olefin polymer was removed from the test tube and then subjected to degradation and reduction.

[0114] The performance of the saturated cyclic olefin polymer obtained in this embodiment was tested: Hydrogenation rate was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight was 3089 g / mol and the molecular weight distribution was 1.73 as determined by GPC; and the Tg of the saturated cyclic olefin polymer obtained in this embodiment was [not specified in the original text]. g It is 86℃.

[0115] Example 11

[0116] Unlike Example 10, the amount of 2,3-dihydrofuran added in the polymerization step was 1.49 g (22.15 mmol, concentration 20 mol%). Performance tests were performed on the saturated cyclic olefin polymer obtained in this example: by 1H NMR spectroscopy and infrared spectroscopy, the hydrogenation rate of the saturated cyclic olefin polymer obtained in this example was greater than 99%; by GPC testing, the molecular weight of the saturated cyclic olefin polymer obtained in this example was 2567 g / mol, and the molecular weight distribution was 1.39; by DSC testing, the Tg of the saturated cyclic olefin polymer obtained in this example was... g The temperature is 81℃.

[0117] Example 12

[0118] Unlike Example 1, the cyclic olefin monomer used in the polymerization was replaced with 5-ethylidene-2-norbornene instead of dicyclopentadiene. The specific polymerization steps were as follows: 20 g (0.17 mol) of 5-ethylidene-2-norbornene was weighed into a test tube, and 1.16 g (16.7 mmol, concentration 10 mol%) of 2,3-dihydrofuran was added and mixed thoroughly. 14 mg (100 ppm) of Grubbs' second-generation catalyst was weighed and dissolved in 0.5 ml of dichloromethane. This catalyst solution was slowly added to the mixture of 5-ethylidene-2-norbornene and 2,3-dihydrofuran, and the mixture was vigorously shaken and mixed thoroughly. The mixture was then placed in a 40°C oven for 4 hours. After polymerization, the first cyclic olefin polymer solidified block was removed from the test tube for degradation and reduction.

[0119] The performance of the saturated cyclic olefin polymer obtained in this embodiment was tested: Hydrogenation rate of the saturated cyclic olefin polymer was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight of the saturated cyclic olefin polymer obtained in this embodiment was 3328 g / mol and the molecular weight distribution was 1.25 as determined by GPC; the Tg of the saturated cyclic olefin polymer obtained in this embodiment was [not specified in the original text]. g It is 83℃.

[0120] The reactions of other norbornene derivatives are similar to those in this embodiment, and the chemical reaction structures are as follows: Figure 2 As shown.

[0121] Example 13

[0122] Unlike Example 1, hydrogen gas was used as the reducing agent in the hydrogenation reduction step. The specific steps of the hydrogenation reduction were as follows: 1.3 g (0.01 mmol) of the second cyclic olefin polymer was weighed into a hydrogenation reactor, 100 ml of o-xylene was added and stirred to disperse it, 0.47 mg of RuHCl(CO)(PPh3)3 (0.5 μmol) was dissolved in 0.5 ml of toluene (as an organic solvent for dissolving the hydrogenation catalyst), and then added to the reactor. The temperature was raised to 80 °C, and then hydrogen gas was introduced while maintaining a pressure of 0.8 MPa. The reaction was carried out for 12 h. After the reaction was completed, hydrogen gas was slowly released, and the solid product was washed with methanol and dried to obtain a white powdery saturated cyclic olefin polymer.

[0123] The performance of the saturated cyclic olefin polymer obtained in this embodiment was tested: Hydrogenation rate was greater than 99% as determined by 1H NMR and infrared spectroscopy; the molecular weight was 2983 g / mol and the molecular weight distribution was 1.43 as determined by GPC; and the Tg of the saturated cyclic olefin polymer obtained in this embodiment was [not specified in the original text]. g It is 90℃.

[0124] Taking the performance test of Example 1 as an example, the performance of the saturated cyclic olefin polymer prepared by the method of the present invention will be described in detail.

[0125] The second cyclic olefin polymer and the saturated cyclic olefin polymer (i.e., the polymers before and after hydrogenation reduction) in Example 1 were measured by infrared spectroscopy, and the test results are as follows: Figure 3 As shown in the figure. According to relevant literature, the stretching vibration absorption peak of the C=C double bond is in the range of 1680-1600 cm⁻¹. -1 However, due to the substituted alkyl groups on the double bonds in the polymer chain and their asymmetry, the absorption peak is relatively weak. Compared with the infrared spectrum of second-cyclic olefin polymers, the absorption peak is 1680-1600 cm⁻¹. -1 The absorption peak shows a recognizable area reduction after hydrogenation reduction. Simultaneously, the absorption peak for the out-of-plane bending vibration of CH on the double bond is located at 1000-700 cm⁻¹. -1 place, Figure 3 970cm -1 942cm -1 754cm -1 731cm -1 705cm -1 The peak at 1000-700 cm⁻¹ can be identified as an absorption peak due to the out-of-plane bending vibration of the CH bond on the double bond in the polymer chain. Compared with the infrared spectrum of polymers with second-ring olefins, this peak is located at 1000-700 cm⁻¹. -1The peak area decreased significantly within the range, which means that the out-of-plane bending vibration absorption peak of the C=C double bond disappeared. Therefore, it was determined that the double bond in the polymer chain was reduced.

[0126] Then, the hydrogenation rate of the second cyclic olefin polymer and the saturated cyclic olefin polymer in Example 1 was determined by measuring their respective proton nuclear magnetic resonance spectra. (See [reference]). Figure 4 According to relevant literature, the chemical shift of CH on the double bond is at δ = 4.5–6.5. From the 1H NMR spectrum of the second cyclic olefin polymer, the chemical shift value δ = 5.2–5.7 represents the hydrogen on the double bond in the polymer chain. However, no significant peak is observed at this position in the 1H NMR spectrum of the reduced saturated cyclic olefin polymer. Therefore, it can be determined that the double bond is completely hydrogenated. Integral calculations show that the hydrogenation rate is above 99%. The hydrogenation rates of the saturated cyclic olefin polymers in other embodiments were also determined using this method, and all were above 99%. Because almost all carbon-carbon double bonds are hydrogenated, the saturated cyclic olefin polymers exhibit greater chemical stability and stronger oxidation resistance, and the five-membered ring structure gives them excellent rigidity.

[0127] The saturated cyclic olefin polymer in Example 1 was characterized by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The gel permeation chromatogram of the saturated cyclic olefin polymer in Example 1 is shown below. Figure 5 As shown in the figure, the heat flow curve is as follows: Figure 6 As shown.

[0128] from Figure 5 According to the GPC test results, the relative molecular weight of the saturated cyclic olefin polymer in Example 1 is M. n =3077 g / mol, with a molecular weight distribution of 1.51. The molecular weights of the saturated cyclic olefin polymers in the various examples ranged from 2567 to 4235 g / mol, with molecular weight distributions ranging from 1.25 to 1.82. Lower molecular weights and a wider molecular weight distribution are beneficial for polymer processing and molding.

[0129] from Figure 6 According to the DSC test results, the glass transition temperature T of the saturated cyclic olefin polymer in Example 1 is... g The glass transition temperature (Tg) of the saturated cyclic olefin polymers in all embodiments was 94.96℃, and the Tg of all examples was below 100℃. The glass transition temperature of general thermoplastic materials is below 100℃, indicating that the saturated cyclic olefin polymers obtained by the method of this invention are thermoplastic materials, easily extruded, injection molded, calendered, blow molded, and thermoformed. Furthermore, the saturated cyclic olefin polymers obtained by the method of this invention are solid at room temperature, have high hardness and low moisture absorption, and when heated to around 120℃, the polymer changes from powder to a transparent liquid with good flowability.

[0130] In summary, the method for recycling and reusing cyclic olefin polymers of the present invention can transform thermosetting materials into a class of thermoplastic polymer materials with excellent rigidity, oxidation resistance, chemical stability, good fluidity in the molten state, high hardness at room temperature, and low moisture absorption, suitable for extrusion, injection molding, calendering, blow molding, and thermoforming, thus expanding their product application range.

[0131] To further illustrate the inventiveness of this invention, the following comparative examples specifically demonstrate the key regulatory role played by the molar ratio of cyclic olefin monomers to monomers containing olefinic ether bonds in the degradation of long-chain cyclic olefin polymers and the subsequent preparation of thermoplastic polymers.

[0132] Comparative Example 1

[0133] Unlike Example 1, the molar ratio of dicyclopentadiene to 2,3-dihydrofuran used in the polymerization was adjusted to 30:1. The specific polymerization steps were as follows: 10 g (0.11 mol) of dicyclopentadiene was weighed into a test tube, and 7.71 g (3.67 mmol, concentration 3.33 mol%) of 2,3-dihydrofuran was added and mixed thoroughly. 9 mg (100 ppm) of Grubbs second-generation catalyst was weighed and dissolved in 0.5 ml of dichloromethane. This catalyst solution was slowly added to the mixture of dicyclopentadiene and 2,3-dihydrofuran, and the mixture was vigorously shaken and mixed thoroughly. The mixture was then placed in a 100°C oven and heated for 4 hours. After polymerization, the solidified block of the first cyclic olefin polymer was removed from the test tube and then attempted to degrade it. It was found that the solidified block of this comparative example (Comparative Example 1) only swelled in the acidic degradation solution and did not degrade into a liquid, making it impossible to purify or proceed with the subsequent hydrogenation process.

[0134] Comparative Example 2

[0135] Unlike Example 1, the molar ratio of dicyclopentadiene to 2,3-dihydrofuran used in the polymerization was adjusted to 1:1. The specific polymerization steps were as follows: 10 g (0.11 mol) of dicyclopentadiene was weighed into a test tube, and 0.25 g (0.11 mol, concentration 100 mol%) of 2,3-dihydrofuran was added and mixed thoroughly. 9 mg of Grubbs second-generation catalyst was weighed and dissolved in 0.5 ml of dichloromethane. This catalyst solution was slowly added to the mixture of dicyclopentadiene and 2,3-dihydrofuran, and the mixture was vigorously shaken and mixed thoroughly. The mixture was then placed in a 100°C oven and heated for 4 hours. After heating, it was found that the degree of polymerization in this comparative example (Comparative Example 2) was very low, with a product viscosity of approximately 300 mPa·s, which did not have industrial application value for thermosetting polymers.

[0136] Comparative Example 3

[0137] Unlike Example 1, the molar ratio of dicyclopentadiene to 2,3-dihydrofuran used in the polymerization was adjusted to 2:1. The specific polymerization steps were as follows: 20 g (0.22 mol) of dicyclopentadiene was weighed into a test tube, and 0.25 g (0.11 mol, concentration 100 mol%) of 2,3-dihydrofuran was added and mixed thoroughly. 18 mg of Grubbs second-generation catalyst was weighed and dissolved in 0.5 ml of dichloromethane. This catalyst solution was slowly added to the mixture of dicyclopentadiene and 2,3-dihydrofuran, and the mixture was vigorously shaken and mixed thoroughly. The mixture was then placed in a 100°C oven and heated for 4 hours. After polymerization, the first cyclic olefin polymer was removed; at this point, the polymer was soft and elastic. Subsequently, the first cyclic olefin polymer was degraded and hydrogenated in an acidic degradation solution. The performance of the saturated cyclic olefin polymer obtained in Comparative Example 3 was tested: Hydrogenation rate of the saturated cyclic olefin oligomer obtained in Comparative Example 3 was greater than 99% as determined by 1H NMR and infrared spectroscopy; the weight-average molecular weight of the saturated cyclic olefin polymer obtained in Comparative Example 3 was 711 g / mol as determined by GPC; and the TL of the saturated cyclic olefin oligomer obtained in Comparative Example 3 was [not specified in the original text]. g Below -24℃, it is not suitable for further processing as a thermoplastic resin.

[0138] It should be noted that "an embodiment" or "an embodiment" in this application refers to a specific feature, structure, or characteristic that can be included in at least one implementation of the present invention. The phrases "in one embodiment" and "an embodiment" appearing in different places in this specification do not all refer to the same embodiment, nor are they embodiments that are mutually exclusive, either alone or selectively, with other embodiments. The terms "comprising" or "including" indicate the presence of the claimed feature but do not exclude the presence of one or more other features. The term "and / or" as used in this application includes any and all combinations of one or more of the related listed items. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0139] The present invention has the following beneficial effects:

[0140] 1) This invention degrades biodegradable cyclic olefin polymers and hydrogenates the degraded short-chain polymers using a reducing agent to obtain a class of thermoplastic polymer materials with excellent rigidity and oxidation resistance, stable chemical properties, good fluidity in the molten state, high hardness and low moisture absorption at room temperature, good formability and thermoplasticity, suitable for extrusion, injection molding, calendering, blow molding and thermoforming. As an upgraded recycling material, it has outstanding performance advantages and can be used in injection molding, 3D printing and other processing methods, with a wide range of applications.

[0141] 2) This invention provides a direction for the recycling and reuse of thermosetting materials and is of great significance for the recycling and reuse of thermosetting polymers.

[0142] 3) This invention uses different reducing agents to hydrogenate short-chain polymers, and the hydrogenation rate can reach more than 99%.

[0143] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments. Various corresponding modifications and variations can be made by those skilled in the art according to the present invention without departing from its spirit and essence, but all such modifications and variations should fall within the protection scope of the present invention.

Claims

1. A method for recycling and reusing cyclic olefin polymers, characterized in that, Includes the following steps: Step S1: Provide a first cyclic olefin polymer obtained by copolymerization of a cyclic olefin monomer and a monomer containing an olefin ether bond, wherein the molar ratio of the cyclic olefin monomer to the monomer containing an olefin ether bond is 1:0.05 to 1:0.

2. Step S2: The first cyclic olefin polymer is placed in an acidic degradation solution for degradation, and then a weak base is added for neutralization and concentration to precipitate the second cyclic olefin polymer. The chain length of the second cyclic olefin polymer is shorter than that of the first cyclic olefin polymer. Step S3: Hydrogenate the second cyclic olefin polymer to obtain a saturated cyclic olefin polymer.

2. The method for recycling and reusing cyclic olefin polymers according to claim 1, characterized in that, Step S3 includes: Step S301: Disperse or dissolve the second cyclic olefin polymer in the first solvent; Step S302: Add reducing agent to obtain the solution to be hydrogenated; Step S303: The solution to be hydrogenated is subjected to a hydrogenation reaction at a hydrogenation temperature to obtain a saturated cyclic olefin polymer.

3. The method for recycling and reusing cyclic olefin polymers according to claim 2, characterized in that, The method has at least one of the following characteristics: The first solvent is o-xylene, or a mixture of o-xylene and dimethylacetamide; The reducing agent is hydrogen, a mixture of nitrogen and hydrogen, or a mixture of hydrogen and argon. The hydrogenation temperature is 80–135°C, and the hydrogenation reaction time is 4–48 hours.

4. The method for recycling and reusing cyclic olefin polymers according to claim 2, characterized in that, The method has at least one of the following characteristics: The first solvent is methanol, tetrahydrofuran, toluene, or dimethyl sulfoxide; The reducing agent is p-toluenesulfonyl hydrazine, dipotassium azobiscarboxylate, or hydrazine hydrate. The hydrogenation temperature is 60–140°C, and the hydrogenation reaction time is 4–48 h.

5. The method for recycling and reusing cyclic olefin polymers according to claim 4, characterized in that, The method has at least one of the following characteristics: Step S302 includes: dispersing or dissolving the second cyclic olefin polymer in a first solvent, adding ethanolamine to prepare an ethanolamine solution, and then adding the reducing agent to the ethanolamine solution to obtain the solution to be hydrogenated; Step S303 includes: heating the solution to be hydrogenated to the hydrogenation temperature to perform a hydrogenation reaction to obtain a hydrogenation reaction solution; cooling the hydrogenation reaction solution to room temperature and adding a poor solvent to precipitate a saturated cyclic olefin polymer; filtering and drying the saturated cyclic olefin polymer. The saturated cyclic olefin polymer in step S303 has a molecular weight of 2500-4500 g / mol.

6. The method for recycling and reusing cyclic olefin polymers according to any one of claims 1-5, characterized in that, The first cyclic olefin polymer was prepared by a method comprising the following steps: Mix cyclic olefin monomers with monomers containing olefin ether bonds; Add a ring-opening metathesis polymerization catalyst dissolved in a second solvent; After heating to the polymerization temperature, ring-opening metathesis polymerization is carried out to obtain the first cyclic olefin polymer.

7. The method for recycling and reusing cyclic olefin polymers according to claim 6, characterized in that, The method has at least one of the following characteristics: The monomer containing the olefinic ether bond is 2,3-dihydrofuran; The cyclic olefin monomer is selected from one or more of dicyclopentadiene, norbornene, and norbornene derivatives, and the norbornene derivative is selected from one or more of 5-ethylidene-2-norbornene, 5-norbornene-2,3-dicarboxylic anhydride, 3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, and 5-norbornene-2,3-dicarboximide. The ring-opening metasomatic polymerization catalyst includes at least one of Grubbs first-generation catalyst, Grubbs second-generation catalyst, Grubbs third-generation catalyst, and Hoveyda Grubbs catalyst; The second solvent is tetrahydrofuran, dichloromethane, diphenyl ether, dichloroethane, toluene, xylene, or methyl fluoroether.

8. The method for recycling and reusing cyclic olefin polymers according to claim 6, characterized in that, The method has at least one of the following characteristics: The amount of the ring-opening metathesis polymerization catalyst relative to the cyclic olefin monomer is 0.1 ppm to 200 ppm; The polymerization temperature is 40℃~140℃, and the ring-opening metathesis polymerization time is 0.5h~24h.

9. The method for recycling and reusing cyclic olefin polymers according to any one of claims 1-5, characterized in that, Step S2 includes: The first cyclic olefin polymer is placed in an acidic degradation solution for degradation until the first cyclic olefin polymer is completely dissolved to obtain a first solution; Add a weak base to the first solution until no more bubbles are produced when the weak base is added to the first solution, to obtain a second solution; The second solution is concentrated until a solid precipitates out. Methanol is then added, and the precipitate yields a second cyclic olefin polymer.

10. The method for recycling and reusing cyclic olefin polymers according to claim 9, characterized in that, The method has at least one of the following characteristics: The acidic degradation solution is a solution obtained by dissolving hydrochloric acid in tetrahydrofuran, and the concentration of hydrochloric acid in the acidic degradation solution is 0.5 mol / L to 2 mol / L; The weak base is sodium bicarbonate.

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