Preparation method of saturated cycloolefin copolymer with clear structure based on dicyclopentadiene

Abstract

The invention relates to the field of polymer preparation, in particular to a preparation method of a saturated cycloolefin copolymer with a clear structure based on dicyclopentadiene. The preparation method comprises the following steps: step 1, adding an organic solvent, dicyclopentadiene, a main catalyst and a cocatalyst into a reaction system for polymerization reaction in the presence of ethylene without water and oxygen to obtain a copolymer solution; precipitating the copolymer solution to obtain a cycloolefin copolymer before hydrogenation; step 2, adding the cycloolefin copolymer before hydrogenation into a solvent, dissolving, and carrying out hydrogenation reaction with hydrogen and a hydrogenation catalyst to obtain a hydrogenated polymer solution; and step 3, precipitating the hydrogenated polymer solution to obtain the saturated cycloolefin copolymer. The monomer dicyclopentadiene for preparing the saturated cycloolefin copolymer is rich in source and low in price, the production cost is lower, polymerization and hydrogenation conditions are mild, and the method has a relatively high industrial prospect.

Description

Technical Field

[0001] The present invention relates to the field of polymer preparation, and particularly to a method for preparing a structurally defined saturated cycloolefin copolymer based on dicyclopentadiene. Background Art

[0002] Cyclic olefin copolymer (COC for short) is a kind of polymer prepared by copolymerizing cyclic olefin monomers with α-olefins, etc. It has the characteristics of low density, low hygroscopicity, high transparency, high heat resistance, high refractive index and excellent processability. It is an amorphous thermoplastic polymer material that has attracted great attention in the industrial and academic circles in recent years and has broad application prospects in the fields of optical lenses, electronics, pharmaceutical packaging, etc.

[0003] At present, the mainstream process routes for preparing COC are ethylene / norbornene copolymer and ethylene / dimethylbicyclooctane copolymer. Among them, norbornene and dimethylbicyclooctane are mainly prepared by the Diels-Alder (DA) reaction using liquid-phase or gas-phase processes. The products obtained by the reaction need to be separated and purified to reach the polymerization grade before they can be used for the preparation of COC. The production process is cumbersome, with high energy consumption and high cost. Dicyclopentadiene (DCPD) is an extract from the C5 fraction of the by-products of petroleum cracking ethylene. With the continuous expansion of ethylene production capacity, the output of the C5 fraction is increasing, and the production capacity of dicyclopentadiene is in excess, urgently needing to be developed and utilized. However, since dicyclopentadiene contains two double bonds, both double bonds may undergo polymerization reactions during the copolymerization process, resulting in the formation of complex polymer structures and even cross-linked products. Therefore, the selection of catalysts is crucial. Moreover, due to the residual double bonds in dicyclopentadiene in the generated polymer, cross-linking will occur during long-term use at room temperature or use at high temperature, resulting in poor performance.

[0004] Chinese invention patent CN116082550A discloses a COC based on dicyclopentadiene and a preparation method thereof, wherein ethylene, dicyclopentadiene and substituted styrene are ternary copolymerized to prepare a random copolymer with good thermal oxygen stability. The polymer has good light transmittance and good toughness. However, after the copolymerization of dicyclopentadiene in the patent, the double bonds on the ring still exist. During later application, the residual double bonds are a weak point, which is easy to be oxidized and cross-linked, and the performance of the polymer will be deteriorated. Chinese invention patent CN117362501A discloses a method for directly preparing COC from dicyclopentadiene and ethylene based on a continuous flow reactor, and the method proposes that DCPD is first cracked at high temperature by a continuous flow reactor and prepared by DA addition reaction with ethylene to prepare norbornene, and then the target product norbornene is copolymerized with ethylene during the reaction period to synthesize COC. However, in the reaction process, since DA addition is a reversible reaction, the components in the system are complex, and the cycloolefin monomers involved in the polymerization are a multi-component system, with norbornene, incompletely reacted DCPD, cyclopentadiene generated by DCPD at high temperature, and tricyclopentadiene. These polymerized monomers can be copolymerized with ethylene to obtain a cycloolefin polymer with complex components. The structure and performance of the polymer produced by the polymerization are uncontrollable, and the repeatability is poor. It is not a uniform, well-structured polymer. Chinese invention patent CN105085815A discloses an α-olefin / dicyclopentadiene copolymer and a preparation method thereof, wherein a diamine non-cyclopentadiene catalyst is used to catalyze the copolymerization of α-olefin and dicyclopentadiene; the diamine non-cyclopentadiene catalyst has good activity at room temperature and relatively low temperatures, but the active center is unstable at high temperatures, and the catalyst is easy to decompose, reaching a maximum of 80 and 60°C, respectively. The monomer tolerance and polymerization reaction activity will be greatly reduced, which is difficult to meet the existing industrial production scale-up and high temperature conditions. In the later industrial production, it may face more challenges and require more process production costs. Literature research reports (Polymer chemistry.2024, DOI:10.1039 / d4py00324a) that rare earth scandium catalysts were used to catalyze the copolymerization of ethylene and tricyclopentadiene. Tricyclopentadiene (B&K price: 7,029,000 yuan / 500 grams) is much more expensive than the monomers norbornene (B&K price: 1,135 yuan / 500 grams) and tetracyclododecene (B&K price: 312,500 yuan / 500 grams) used in commercial COC, which is not conducive to industrial production.

[0005] In summary, as a low-priced (B&K sells for 209 yuan / 500g) cycloolefin monomer that has been domestically produced, using it as a comonomer of COC has a very important prospect in the process of achieving the domestic production of COC and its monomers. Developing a cycloolefin copolymer based on dicyclopentadiene can not only solve the problem of expensive monomer sources, but also solve the problem of overcapacity of dicyclopentadiene. Summary of the Invention

[0006] Based on the above, the present invention provides a method for preparing a saturated cycloolefin copolymer with a well-defined structure based on dicyclopentadiene.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention, a method for preparing a saturated cycloolefin copolymer with a well-defined structure based on dicyclopentadiene, comprises the following steps:

[0009] Step 1, under the conditions of anhydrous and anaerobic and the presence of ethylene, add an organic solvent, dicyclopentadiene, a main catalyst and a cocatalyst to a reaction system for polymerization reaction to obtain a copolymer solution; precipitate the copolymer solution to obtain a cycloolefin copolymer before hydrogenation;

[0010] Step 2, dissolve the cycloolefin copolymer before hydrogenation in a solvent, and carry out a hydrogenation reaction with hydrogen and a hydrogenation catalyst to obtain a polymer solution after hydrogenation;

[0011] Step 3, precipitate the polymer solution after hydrogenation to obtain the saturated cycloolefin copolymer (i.e., the cycloolefin copolymer after hydrogenation);

[0012] The main catalyst is one of metallocene complex catalysts having the following formula structure:

[0013]

[0014] Another technical solution of the present invention, a saturated cycloolefin copolymer prepared by the above preparation method.

[0015] The present invention discloses the following technical effects:

[0016] On the basis of ensuring that the polymerization monomer is dicyclopentadiene which is inexpensive and widely sourced, the comonomer is unique and does not require pyrolysis at high temperature. The polymerization process and mechanism are simpler, and the structure and properties of the polymer are more definite and controllable. And after hydrogenation treatment, the obtained polymer is a saturated polymer with a well-defined structure. At the same time, the temperature and pressure in the polymerization process of the present invention are more mild, reducing the waste of monomers and energy. The reaction can be achieved using a traditional reactor without the need to design a new reactor, with lower production costs, higher cost performance and industrial application prospects.

[0017] The present invention uses an inexpensive commercial metallocene catalyst which has been widely used in the industrial field for producing polyolefin materials. It still has stable activity even at a high temperature of 100 °C, strong copolymerization ability and high monomer insertion rate.

[0018] The number-average molecular weight of the saturated cycloolefin copolymer prepared by the present invention is between 10,000 and 500,000, the molecular weight distribution is between 1.2 and 3.0, the insertion rate is between 20% and 70%, and the glass transition temperature T g is between 30 and 180 °C, the visible light transmittance is above 90%, and at the same time, the monomer raw materials are rich in source and low in price, realizing the high-value utilization of dicyclopentadiene. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 is the nuclear magnetic resonance hydrogen spectrum of the cycloolefin copolymer before and after hydrogenation obtained in Example 1 of the present invention;

[0021] Figure 2 is the second heating curve of the differential scanning calorimeter (DSC) of the cycloolefin copolymer before and after hydrogenation obtained in Example 1 of the present invention;

[0022] Figure 3 is the second heating curve of the differential scanning calorimeter (DSC) of the cycloolefin copolymer before and after hydrogenation obtained in Example 3 of the present invention;

[0023] Figure 4 is the GPC curve of the cycloolefin copolymer before hydrogenation obtained in Examples 1-4 of the present invention;

[0024] Figure 5 is the light transmittance of the cycloolefin copolymer after hydrogenation obtained in Examples 1-3 of the present invention;

[0025] Figure 6 is the stress-strain curve of the cycloolefin copolymer after hydrogenation obtained in Example 1 of the present invention;

[0026] Figure 7 is the second heating curve of the differential scanning calorimeter (DSC) of the cycloolefin copolymer before hydrogenation obtained in Examples 3 and 5-8 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation manners of the present invention.

[0028] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to those documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0030] Without departing from the scope or spirit of the present invention, various improvements and variations can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0031] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0032] The "%" mentioned in the present invention represents mass percentage unless otherwise specified.

[0033] The first aspect of the present invention provides a method for preparing a structurally defined saturated cycloolefin copolymer based on dicyclopentadiene, comprising the following steps:

[0034] Step 1, under the conditions of anhydrous and anaerobic and in the presence of ethylene, an organic solvent, dicyclopentadiene, a main catalyst and a cocatalyst are added to a reaction system for a polymerization reaction to obtain a copolymer solution; the copolymer solution is precipitated to obtain a cycloolefin copolymer before hydrogenation;

[0035] Step 2, after dissolving the cycloolefin copolymer before hydrogenation in a solvent, a hydrogenation reaction is carried out with hydrogen and a hydrogenation catalyst to obtain a polymer solution after hydrogenation;

[0036] Step 3, the polymer solution after hydrogenation is precipitated to obtain the saturated cycloolefin copolymer (i.e., the cycloolefin copolymer after hydrogenation);

[0037] The main catalyst is one of the metallocene complex catalysts having the following structure:

[0038]

[0039] If other common catalysts in the art, such as constrained geometry catalysts (CGCs), are used to catalyze the copolymerization of ethylene and DCPD, cross-linked products will be formed, and the resulting polymer is insoluble at high temperatures and does not dissolve under the action of solvents; while using a metallocene catalyst with a lower ligand steric hindrance (cyclopentadienyl), such as Cp 2 ZrCl 2 will result in a low insertion rate of DCPD, causing the polymer to have a melting point, and the resulting polymer is a crystalline polymer, showing an opaque state in terms of performance.

[0040] In Step 1 and Step 2, after precipitation, the steps of suction filtration, washing the obtained precipitate, and drying are further included. The washing is carried out using acetone, and the drying is specifically drying at 40 °C for 24 hours in a vacuum oven.

[0041] In a preferred embodiment of the present invention, in Step 1, the organic solvent is one or more of linear hydrocarbon compounds, cycloalkane compounds, and aromatic hydrocarbon compounds.

[0042] In some specific embodiments of the present invention, the addition method of dicyclopentadiene is: first dissolve dicyclopentadiene in an organic solvent (the same organic solvent as in Step 1) and then add it.

[0043] In a preferred embodiment of the present invention, the cocatalyst is one or more of methylaluminoxane (MAO), a mixture of triisobutylaluminum and tris(pentafluorophenyl)borane, a mixture of triisobutylaluminum and triphenylcarbenium tetrakis(pentafluorophenyl)borate, and modified methylaluminoxane (MMAO) (CAS: 206451-54-9).

[0044] In some specific embodiments of the present invention, methylaluminoxane (MAO) can be methylaluminoxane powder (DMAO).

[0045] In a preferred embodiment of the present invention, the molar ratio of the cocatalyst to the main catalyst is 2000:1 to 100:1.

[0046] More preferably, the molar ratio of the cocatalyst to the main catalyst is 1000:1 to 300:1

[0047] In a preferred embodiment of the present invention, the temperature of the polymerization reaction is 20 to 100 °C, and the time is 1 to 90 min.

[0048] More preferably, the temperature of the polymerization reaction is 20 to 60 °C, and the time is 1 to 10 min.

[0049] In a preferred embodiment of the present invention, in step 1, the pressure of ethylene in the reaction system is 0.1 to 20 MPa.

[0050] More preferably, the pressure of ethylene in the reaction system is 0.1 to 2 MPa.

[0051] In a preferred embodiment of the present invention, in step 1, the concentration of dicyclopentadiene in the reaction system is 0.5 to 2 mmol / mL.

[0052] In a preferred embodiment of the present invention, in step 2, the pressure of hydrogen in the reaction system is 1 to 20 MPa; the temperature of the hydrogenation reaction is 20 to 200 °C, and the time is 0.5 to 72 h;

[0053] More preferably, in step 2, the pressure of hydrogen in the reaction system is 1 to 4 MPa; the temperature of the hydrogenation reaction is 60 to 100 °C, and the time is 0.5 to 12 h.

[0054] The hydrogenation catalyst is one of Raney nickel, 5% - 10% wet palladium carbon, 10% Pd / C, Pd / BaSO 4 , Pt / SiO 2 , nickel acetylacetonate / triisobutylaluminum, (PPh 3 ) 3 RhCl / PPh 3 one of them.

[0055] In a preferred embodiment of the present invention, in steps 1 and 2, the precipitation is carried out using an acidified ethanol solution, where the acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, oxalic acid, and citric acid; the volume percentage of the acid in the ethanol solution is 1% - 10%.

[0056] The cycloolefin copolymer before hydrogenation will crosslink and its performance will deteriorate when used at room temperature for a long time or at high temperature. The performance of the saturated cycloolefin polymer obtained by hydrogenation is more stable.

[0057] The second aspect of the present invention provides a saturated cycloolefin copolymer prepared by the above preparation method. The number-average molecular weight of the saturated cycloolefin copolymer is between 10,000 and 500,000, the molecular weight distribution is between 1.2 and 3.0, the insertion rate is between 20% and 70%, and the glass transition temperature T g is between 30 and 180 °C.

[0058] The hydrogenation degree of the saturated cycloolefin copolymer prepared by the present invention can reach 100%, the light transmittance can reach more than 90%, and the thermal and mechanical properties are excellent. The monomer dicyclopentadiene for preparing the polymer is rich in source and low in price, the production cost is lower, the polymerization and hydrogenation conditions are mild, and it has a high industrialization prospect.

[0059] The test methods related to the present invention are as follows:

[0060] Using a Bruker AC400 nuclear magnetic resonance spectrometer at room temperature 1 1H NMR spectrum, deuterated tetrachloroethane as the solvent, and TMS as the internal standard; using a TA Q2000 differential scanning calorimeter to measure the glass transition temperature of the polymer, with a heating rate of 10 °C / min, a cooling rate of 10 °C / min, a scanning range of 30 - 200 °C, and a second heating curve; using a Shimadzu UV2700 visible-ultraviolet spectrophotometer to measure the light transmittance of the polymer at room temperature; using an Agilent PL-GPC220 high-temperature gel permeation chromatograph to measure the molecular weight and its distribution of the polymer, with a measurement temperature of 150 °C, a mobile phase of 1,2,4-trichlorobenzene added with 0.05 wt% of 2,6-di-tert-butyl-4-methylphenol as an antioxidant, a flow rate set at 1.0 mL / min, and using PL EasiCal PS-1 as the standard sample; using an Instron 3369 universal material testing machine to test the tensile mechanical properties of the obtained polymer.

[0061] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are all purchased from commercial channels or are publicly available.

[0062] The technical solutions provided by the present invention are described in detail below in conjunction with the examples, but they should not be construed as limiting the protection scope of the present invention.

[0063] Example 1

[0064] 1. Under anhydrous and anaerobic conditions, with a polymerization temperature of 40 °C and an ethylene pressure of 0.1 MPa, using xylene as the solvent, xylene, a xylene solution of dicyclopentadiene (containing 64 mmol of dicyclopentadiene in terms of amount of substance), 6 μmol of zirconium metal catalyst (main catalyst) and the corresponding cocatalyst system were successively added to the polymerization flask for the copolymerization reaction of ethylene / dicyclopentadiene. The copolymerization reaction time was 10 min, and the total volume of the reaction system was 40 mL to obtain an ethylene / dicyclopentadiene copolymer solution, where the main catalyst was Ph 2 C(Cp)(9-Flu)ZrCl 2, the cocatalyst is a mixture of triisobutylaluminum and trityl tetrakis(pentafluorophenyl)borate, and the molar ratio of the main catalyst to the cocatalyst is [Zr]:[Al]:[B] = 1:400:2. The polymer solution was poured into an ethanol solution containing 10% (by volume) hydrochloric acid for precipitation. After suction filtration, the filter cake was obtained. Subsequently, the filter cake was rinsed with acetone and dried in a vacuum oven at 40 °C for 24 hours to obtain the cycloolefin copolymer before hydrogenation;

[0065] 2. After dissolving the above cycloolefin copolymer before hydrogenation in methylcyclohexane, hydrogen and the hydrogenation catalyst nickel acetylacetonate / triisobutylaluminum were introduced into the reaction kettle for hydrogenation reaction. The hydrogenation pressure was 2.5 MPa, the hydrogenation temperature was 80 °C, and the hydrogenation time was 6 h;

[0066] 3. The polymer solution after hydrogenation was poured into an ethanol solution containing 10% (by volume) hydrochloric acid for precipitation. After suction filtration, the filter cake was obtained. Subsequently, the filter cake was rinsed with acetone and dried in a vacuum oven at 40 °C for 24 hours to obtain the cycloolefin copolymer after hydrogenation.

[0067] Figure 1 It is the 1 HNMR spectrum of the ethylene / dicyclopentadiene copolymer (cycloolefin copolymer) before and after hydrogenation in Example 1. It can be seen from the figure that the doublet at 5.5 - 5.6 ppm disappeared in the spectrum of the ethylene / dicyclopentadiene copolymer after hydrogenation treatment. This is the performance of the complete hydrogenation of the residual double bond peak in dicyclopentadiene after the hydrogenation reaction. It is proved that the complete hydrogenation effect can be obtained by hydrogenating the ethylene / dicyclopentadiene system with this hydrogenation catalyst system. The insertion rate of DCPD in Example 1 was calculated to be 41.9% by nuclear magnetic resonance hydrogen spectrum. By attributing the peaks of the nuclear magnetic resonance hydrogen spectrum of the polymer before hydrogenation, it can be known that the double bond on the norbornene ring of DCPD was opened during the polymerization process, and at the same time, the double bond on the cyclopentene ring remained unreacted, which proves that the catalyst used has the ability to selectively open double bonds, and the structure of the obtained polymer is clear.

[0068] Figure 2 It is the DSC curve of the ethylene / dicyclopentadiene copolymer before and after hydrogenation prepared in Example 1. It can be seen from the figure that the glass transition temperature of the ethylene / dicyclopentadiene copolymer before hydrogenation can reach 136.3 °C, which has a relatively high glass transition temperature. After hydrogenation, the glass transition temperature decreased by 6 °C, proving that the flexibility of the molecular chain decreased after hydrogenation.

[0069] Figure 6 It is the stress-strain curve of the cycloolefin copolymer after hydrogenation obtained in Example 1. It can be seen from the figure that the tensile strength of the obtained polymer is above 50 MPa and the elongation at break is 5%, proving that it has good mechanical properties.

[0070] Example 2

[0071] It is only different from Example 1 in that the main catalyst is changed from Ph 2 C(Cp)(9-Flu)ZrCl 2 to rac-Et(Ind) 2 ZrCl 2 , and the remaining steps and parameters are the same as those in Example 1.

[0072] Example 3

[0073] It is only different from Example 1 in that the main catalyst is changed from Ph 2 C(Cp)(9-Flu)ZrCl 2 to Me 2 C(Cp)(9-Flu)ZrCl 2 , and the remaining steps and parameters are the same as those in Example 1.

[0074] Figure 3 Figure [ID number] is the DSC curve of the ethylene / dicyclopentadiene copolymer before and after hydrogenation prepared in Example 3. It can be seen from the figure that the glass transition temperature of the ethylene / dicyclopentadiene copolymer before hydrogenation can reach 140.5 °C, having a relatively high glass transition temperature. After hydrogenation, the glass transition temperature decreases by 7.4 °C, proving that the flexibility of the molecular chain decreases after hydrogenation.

[0075] Figure 5 Figure [ID number] is the light transmittance curve of the ethylene / dicyclopentadiene copolymer prepared in Examples 1 - 3. It can be seen from the figure that the light transmittance of the obtained ethylene / dicyclopentadiene copolymer is above 85%, proving that the obtained polymer has good transparency in the visible light region.

[0076] Example 4

[0077] It is only different from Example 1 in that the main catalyst is changed from Ph 2 C(Cp)(9-Flu)ZrCl 2 to Me 2 Si(Ind) 2 ZrCl 2 , and the remaining steps and parameters are the same as those in Example 1.

[0078] Figure 4 Figure [ID number] is the GPC curve of the ethylene / dicyclopentadiene copolymer prepared in Examples 1 - 4. It can be seen from the figure that the obtained ethylene / dicyclopentadiene copolymer has a relatively low molecular weight distribution (PDI = 1.6 - 1.8), and at the same time, the obtained polymer also has a relatively high molecular weight (29 - 119 kDa).

[0079] Example 5

[0080] The difference from Example 3 is only that the amount of dicyclopentadiene in the xylene solution of dicyclopentadiene is 20 mmol, and the remaining steps and parameters are the same as those in Example 3.

[0081] Example 6

[0082] The difference from Example 3 is only that the amount of dicyclopentadiene in the xylene solution of dicyclopentadiene is 40 mmol, and the remaining steps and parameters are the same as those in Example 3.

[0083] Example 7

[0084] The difference from Example 3 is only that the amount of dicyclopentadiene in the xylene solution of dicyclopentadiene is 48 mmol, and the remaining steps and parameters are the same as those in Example 3.

[0085] Example 8

[0086] The difference from Example 3 is only that the amount of dicyclopentadiene in the xylene solution of dicyclopentadiene is 80 mmol, and the remaining steps and parameters are the same as those in Example 3.

[0087] Figure 7 This is the second heating curve of differential scanning calorimeter (DSC) for the unhydrogenated ethylene / dicyclopentadiene copolymer obtained in Example 3 and Examples 5 - 8 of the present invention. It can be seen from the figure that by regulating the addition amount of monomer DCPD, the glass transition temperature of the obtained polymer can be changed, and it has a wide adjustment range (T g = 60 - 170 °C).

[0088] The above - described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a saturated cycloolefin copolymer with a clear structure based on dicyclopentadiene, characterized in that: The following steps are involved: Step 1, in the absence of water and oxygen and in the presence of ethylene, adding an organic solvent, dicyclopentadiene, a main catalyst and a co-catalyst to a reaction system for polymerization reaction to obtain a copolymer solution; precipitating the copolymer solution to obtain a cycloolefin copolymer before hydrogenation; Step 2, adding the cycloolefin copolymer before hydrogenation into a solvent for dissolution, and then performing a hydrogenation reaction with hydrogen and a hydrogenation catalyst to obtain a hydrogenated polymer solution; Step 3, precipitating the hydrogenated polymer solution to obtain the saturated cycloolefin copolymer; The main catalyst is one of the metallocene complex catalysts having the following structure:

2. The preparation method according to claim 1, characterized in that: In step 1, the organic solvent is one or more of straight-chain hydrocarbon compounds, cyclic hydrocarbon compounds and aromatic hydrocarbon compounds.

3. The preparation method according to claim 1, characterized in that: The cocatalyst is one or more of methylaluminoxane, a mixture of triisobutylaluminum and tri(pentafluorophenyl)borane, a mixture of triisobutylaluminum and triphenylcarbon tetrakis-(pentafluorophenyl)borate, and modified methylaluminoxane.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the co-catalyst to the main catalyst is 2000:1 to 100:

1.

5. The preparation method according to claim 1, characterized in that: The polymerization reaction is carried out at a temperature of 20 to 100° C. and for a time of 1 to 90 minutes.

6. The preparation method according to claim 1, characterized in that: In step 1, the pressure of ethylene in the reaction system is 0.1 to 20 MPa.

7. The preparation method according to claim 1, characterized in that: In step 1, the concentration of dicyclopentadiene in the reaction system is 0.5 to 2 mmol / mL.

8. The preparation method according to claim 1, characterized in that: In step 2, the pressure of hydrogen in the reaction system is 1 to 20 MPa; the temperature of the hydrogenation reaction is 20 to 200° C., and the time is 0.5 to 72 h; The hydrogenation catalyst is one of Raney nickel, 5% to 10% wet palladium carbon, 10% Pd / C, Pd / BaSO4, Pt / SiO2, nickel acetylacetonate / triisobutylaluminum, and (PPh3)3RhCl / PPh3.

9. The preparation method according to claim 1, characterized in that: In step 1 and step 2, the precipitation is carried out using an acidified ethanol solution, wherein the acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, oxalic acid, and citric acid; and the volume percentage of the acid in the ethanol solution is 1% to 10%.

10. The saturated cycloolefin copolymer prepared according to the preparation method according to any one of claims 1 to 9.

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