Cyclic olefin copolymer, preparation method and application thereof in virtual reality head mounted display

Abstract

The present invention relates to the technical field of polymer compounds obtained by reacting only carbon-carbon unsaturated bonds, and specifically discloses a cycloolefin copolymer, a preparation method and its application in a virtual reality head-mounted display. The present invention uses a solvent as a medium, and uses norbornene, spirofluorene-based olefin monomers and ethylene as polymerization monomers, and performs polymerization reaction under the condition of the presence of a catalyst to obtain the cycloolefin copolymer. The cycloolefin copolymer not only has a high transparency, but also has excellent refractive index and mechanical properties, thereby expanding the application range of the polymer.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer compounds obtained by reacting only carbon-carbon unsaturated bonds, and in particular to a cycloolefin copolymer, a preparation method and an application thereof in a virtual reality-level head-mounted display. Background Art

[0002] Cyclic olefin copolymer is a type of amorphous polymer formed by copolymerization of ethylene or α-olefin and cycloolefin. It has many outstanding excellent properties, such as high light transmittance, high chemical stability, high thermal stability, low birefringence, low density, low hygroscopicity, low dielectric loss, etc. Cyclic olefin copolymer is widely used in the field of optical devices, such as: mobile phone lens, security lens, car lens, camera, camera lens, printer lens, terahertz lens, AR / VR, HUD, mirror reflector, light guide panel, light control panel and reflective film of LCD, thin film for LCD background, optical disc, optical fiber, etc. Compared with other fields, such as packaging and medical fields, the application of cyclic olefin copolymer in the optical field has the highest requirements for various properties of materials. Compared with traditional optical glass, optical grade cyclic olefin copolymer material has the advantages of light weight and strong plasticity, making it the preferred material for preparing optical components.

[0003] Compared with PMMA (polymethyl methacrylate), cycloolefin copolymer materials have comparable optical properties and higher heat resistance than PC (polycarbonate), and also have better dimensional stability than PMMA and PC. Therefore, cycloolefin copolymer materials are the preferred materials for optical lenses such as mobile phones, AR / VR, etc. In addition to lenses, film materials made of cycloolefin copolymers can be used for various screens, such as display polarizers in electronic products.

[0004] CN202011549213.1 relates to the field of cycloolefin copolymers, and more specifically, the invention relates to a cycloolefin copolymer and a method for preparing the same, wherein the structural units of the cycloolefin copolymer are (a) and (b) and / or the glass transition temperature of the cycloolefin copolymer is 100-400°C, the number average molecular weight is 1000-10000000; and the molecular weight distribution is 1.1-3.5. The invention uses styrene monomers and cycloolefin monomers to copolymerize to prepare cycloolefin copolymers, the polymerization system has high activity, and the structure and properties of the polymer, such as molecular weight, molecular weight distribution, cycloolefin content, glass transition temperature, etc., can be adjusted over a wide range. At the same time, the number average molecular weight of the cycloolefin in the invention can meet the requirements of industrial application. In addition, the method for preparing cycloolefin copolymers described in the invention is suitable for the current industrial production conditions and processing methods of polymers.

[0005] CN201510705169.1 provides a cycloolefin copolymer having a structure of formula I, wherein 240≤x≤480, 30≤y≤150. The cycloolefin copolymer provided by the invention has good thermal stability and mechanical properties. In addition, the molecular weight of the cycloolefin copolymer provided by the invention is adjustable and has good transparency. The experimental results show that the glass transition temperature of the cycloolefin copolymer provided by the invention is 137.9℃~221.5℃, the 10% thermal weight loss is more than 320℃, the tensile strength is 43MPa~50MPa, the tensile modulus is 2300MPa~3000MPa, the elongation at break is 2.2%~8.6%, the number average molecular weight of the cycloolefin copolymer provided by the invention is 180kg / mol~370kg / mol, and the light transmittance of the cycloolefin copolymer provided by the invention is >90%.

[0006] In recent years, the field of virtual reality (VR) has developed rapidly and is considered to be the next generation computing platform. Its display form, head-mounted displays, has high requirements for optical performance. Glass lenses are a common solution, but as consumer electronics products, they have the need for lightweight and cost reduction, providing good development opportunities for optical plastics. Cyclic olefin copolymers are used as AR / VR optical lenses, which can also effectively achieve the lightweight and thinness of AR / VR devices and provide beneficial optical properties. However, the current cyclic olefin copolymers have problems with insufficient refractive index and transparency, making it difficult to meet the requirements of optical lenses. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a cyclic olefin copolymer, a preparation method and an application thereof in a virtual reality-level head-mounted display.

[0008] High refractive index is crucial for optical devices. When the refractive index of the material is higher, the optical device can be thinner, which not only means the improvement of performance but also can achieve the goal of lightweight materials, which is very important for the role of virtual reality head-mounted displays. In the present invention, the inventor introduces an aromatic group with a high molar refractive index into a spirofluorene-based olefin monomer, and then polymerizes it with norbornene and ethylene to obtain a cycloolefin copolymer. Since the fluorene part is perpendicular to the polymer main chain, the free volume fraction around the fluorene part provides high solubility and processability. In terms of optical properties, polarization anisotropy can be offset by the cardo structure, and the spirofluorene part of the vertically oriented polymer main chain can offset the high refractive index in the stretching direction, thereby reducing polarization anisotropy, achieving low birefringence and high refraction, thereby achieving high transmittance. Due to the influence of the high refractive group, a high refractive index cycloolefin copolymer with a certain toughness is obtained, and the large steric hindrance and strong rigid structure of the spirofluorene base itself can also bring about the improvement of mechanical properties, thereby further improving the performance of the cycloolefin copolymer.

[0009] To achieve the above object, the present invention provides a method for preparing a cycloolefin copolymer, comprising the following steps:

[0010] In a nitrogen atmosphere, norbornene and spirofluorene monomers are mixed with a solvent and heated.

[0011] A mixed solution of the catalyst and the solvent is added, ethylene is passed until the pressure reaches 0.1-0.2 MPa, the mixture is stirred for 1-2 hours, heating is stopped, and ethanol acidified with hydrochloric acid is injected to terminate the reaction. The product is washed, filtered, and then dried in vacuum to obtain the cycloolefin copolymer.

[0012] Furthermore, the concentration of norbornene is 0.2-1 mol / L.

[0013] Furthermore, the concentration of the spirofluorene monomer is 0.1-0.5 mol / L.

[0014] Furthermore, the molar ratio of the catalyst to norbornene is 1:1-10.

[0015] Furthermore, the solvent is one of n-hexane, cyclohexane, cyclopentane, methylcyclohexane, benzene, toluene and xylene.

[0016] Furthermore, the heating temperature ranges from 70 to 80°C.

[0017] Furthermore, the catalyst is a metallocene, which may be Cp 2 ZrCl 2 、(Ind) 2 ZrCl 2 ,rac-[Et(Ind) 2 ]ZrCl 2 rac-[Et(Ind-H 4 ) 2 ]ZrCl 2 One of them.

[0018] Furthermore, the catalyst also includes an aluminoxane compound, which may be methylaluminoxane or modified methylaluminoxane.

[0019] Preferably, the molar ratio of the metallocene to norbornene is 1:1000-4000, and the molar ratio of the metallocene to the aluminoxane compound is 1:500.

[0020] The method for preparing the spirofluorene-based olefin monomer comprises the following steps:

[0021] X1. Add 10-20 parts by weight of p-toluenesulfonyl chloride and 0.1-0.5 parts by weight of 4-dimethylaminopyridine to 60-80 parts by weight of pyridine to obtain solution A, and add 2-8 parts by weight of 5-norbornene-2-endo,3-endo-dimethanol to 10-20 parts by weight of pyridine to obtain solution B; add solution A to solution B, cool to 0-5°C and stir for 12-18h, concentrate to remove the solvent after stirring, extract the residue with chloroform, wash with water and brine, and dry for the next step;

[0022] X2. Add 10-20 parts by weight of 2,7-bis(phenylmethyl)-9H-fluorene to 20-50 parts by weight of tetrahydrofuran, mix well, then add dropwise 50-100 parts by weight of n-butyllithium in n-hexane at -80--70°C, and continue stirring at -80--70°C for 1-2 hours to obtain a mixture C; add 10-20 parts by weight of the product in step X1 to 100-200 parts by weight of tetrahydrofuran, mix well to obtain a solution D; add dropwise solution D to mixture C at -80--70°C, warm to room temperature after the addition is complete, stir for 10-20 hours, extract with chloroform to obtain an organic phase, and then wash with water, dry, and concentrate to obtain a spirofluorene monomer.

[0023] The present invention also provides a cycloolefin copolymer prepared by the method and application of the cycloolefin copolymer in a virtual reality-level head-mounted display.

[0024] Beneficial effects of the present invention:

[0025] The present invention uses a solvent as a medium, and uses norbornene, spirofluorene monomers and ethylene as polymerization monomers, and performs polymerization reaction under the condition of the presence of a catalyst to obtain the cycloolefin copolymer. The cycloolefin copolymer not only has high transparency, but also has excellent refractive index and mechanical properties, thereby expanding the application range of the polymer. DETAILED DESCRIPTION

[0026] 2,7-bis(phenylmethyl)-9H-fluorene, CAS No.: 578766-02-6.

[0027] 2-phenyl-9H-fluorene, CAS number: 28065-98-7.

[0028] n-Butyl lithium in n-hexane solution, 1.6 mol / L.

[0029] rac-[Et(Ind) 2 ]ZrCl 2 ,witco company.

[0030] Comparative Example 1 A method for preparing a cycloolefin copolymer comprises the following steps:

[0031] In a nitrogen atmosphere, norbornene and 5-norbornene-2-methanol were mixed with toluene, the concentration of norbornene was 0.8 mol / L, and the concentration of 5-norbornene-2-methanol was 0.2 mol / L, and the mixture was heated to 80°C and added with rac-[Et(Ind) 2 ]ZrCl 2 , a mixture of methylaluminoxane and toluene, rac-[Et(Ind) 2 ]ZrCl 2 The molar ratio of rac-[Et(Ind) 2 ]ZrCl 2 The molar ratio of ethylene to methylaluminoxane is 1:500, ethylene is introduced until the pressure reaches 0.1 MPa, and the mixture is stirred for 2 hours, and then heating is stopped. Ethanol acidified with hydrochloric acid is injected to terminate the reaction. The product is washed, filtered, and then dried in vacuum to obtain the cycloolefin copolymer.

[0032] Embodiment 1 A method for preparing a cycloolefin copolymer comprises the following steps:

[0033] In a nitrogen atmosphere, norbornene and spirofluorene monomers were mixed with toluene, the concentration of norbornene was 0.8 mol / L, and the concentration of spirofluorene monomer was 0.2 mol / L, and the mixture was heated to 80°C and added with rac-[Et(Ind) 2 ]ZrCl 2 , a mixture of methylaluminoxane and toluene, rac-[Et(Ind) 2 ]ZrCl 2 The molar ratio of rac-[Et(Ind) 2 ]ZrCl 2 The molar ratio of ethylene to methylaluminoxane is 1:500, ethylene is introduced until the pressure reaches 0.1 MPa, and the mixture is stirred for 2 hours, and then heating is stopped. Ethanol acidified with hydrochloric acid is injected to terminate the reaction. The product is washed, filtered, and then dried in vacuum to obtain the cycloolefin copolymer.

[0034] The method for preparing the spirofluorene-based olefin monomer comprises the following steps:

[0035] X1. Add 15 g of p-toluenesulfonyl chloride and 0.3 g of 4-dimethylaminopyridine to 70 mL of pyridine to obtain solution A. Add 5 g of 5-norbornene-2-endo,3-endo-dimethanol to 15 mL of pyridine to obtain solution B. Add solution A to solution B, cool to 0°C and stir for 16 h. After stirring, concentrate to remove the solvent. Extract the residue with chloroform, wash with water and brine, and dry for the next step.

[0036] X2. Add 16 g of 2,7-bis(phenylmethyl)-9H-fluorene to 40 mL of tetrahydrofuran, mix well, then add dropwise 65 mL of n-butyllithium in n-hexane at -76°C, and continue stirring at -76°C for 2 h to obtain a mixture C; add 12 g of the product in step X1 to 150 mL of tetrahydrofuran, mix well to obtain a solution D; add solution D dropwise to mixture C at -76°C, warm to room temperature after the addition is complete, stir for 16 h, extract with chloroform to obtain an organic phase, and then wash with water, dry, and concentrate to obtain a spirofluorene monomer.

[0037] Embodiment 2 A method for preparing a cycloolefin copolymer comprises the following steps:

[0038] In a nitrogen atmosphere, norbornene and spirofluorene monomers were mixed with toluene, the concentration of norbornene was 0.8 mol / L, and the concentration of spirofluorene monomer was 0.2 mol / L, and the mixture was heated to 80°C and added with rac-[Et(Ind) 2 ]ZrCl 2 , a mixture of methylaluminoxane and toluene, rac-[Et(Ind) 2 ]ZrCl 2 The molar ratio of rac-[Et(Ind) 2 ]ZrCl 2 The molar ratio of ethylene to methylaluminoxane is 1:500, ethylene is introduced until the pressure reaches 0.1 MPa, and the mixture is stirred for 2 hours, and then heating is stopped. Ethanol acidified with hydrochloric acid is injected to terminate the reaction. The product is washed, filtered, and then dried in vacuum to obtain the cycloolefin copolymer.

[0039] The method for preparing the spirofluorene-based olefin monomer comprises the following steps:

[0040] X1. Add 15 g of p-toluenesulfonyl chloride and 0.3 g of 4-dimethylaminopyridine to 70 mL of pyridine to obtain solution A. Add 5 g of 5-norbornene-2-endo,3-endo-dimethanol to 15 mL of pyridine to obtain solution B. Add solution A to solution B, cool to 0°C and stir for 16 h. After stirring, concentrate to remove the solvent. Extract the residue with chloroform, wash with water and brine, and dry for the next step.

[0041] X2. Add 12 g of 2-phenyl-9H-fluorene to 40 mL of tetrahydrofuran, mix well, then add dropwise 65 mL of n-butyllithium in n-hexane at -76°C, and continue stirring at -76°C for 2 h to obtain a mixture C; add 12 g of the product in step X1 to 150 mL of tetrahydrofuran, mix well to obtain a solution D; add solution D dropwise to mixture C at -76°C, warm to room temperature after the addition is complete, stir for 16 h, extract with chloroform to obtain an organic phase, and then wash with water, dry, and concentrate to obtain a spirofluorene monomer.

[0042] Embodiment 3 A method for preparing a cycloolefin copolymer comprises the following steps:

[0043] In a nitrogen atmosphere, norbornene and spirofluorene monomers were mixed with toluene, the concentration of norbornene was 0.8 mol / L, and the concentration of spirofluorene monomer was 0.2 mol / L, and the mixture was heated to 80°C and added with rac-[Et(Ind) 2 ]ZrCl 2 , a mixture of methylaluminoxane and toluene, rac-[Et(Ind) 2 ]ZrCl 2 The molar ratio of rac-[Et(Ind) 2 ]ZrCl 2 The molar ratio of ethylene to methylaluminoxane is 1:500, ethylene is introduced until the pressure reaches 0.1 MPa, and the mixture is stirred for 2 hours, and then heating is stopped. Ethanol acidified with hydrochloric acid is injected to terminate the reaction. The product is washed, filtered, and then dried in vacuum to obtain the cycloolefin copolymer.

[0044] The method for preparing the spirofluorene-based olefin monomer comprises the following steps:

[0045] X1. Add 15 g of p-toluenesulfonyl chloride and 0.3 g of 4-dimethylaminopyridine to 70 mL of pyridine to obtain solution A. Add 5 g of 5-norbornene-2-endo,3-endo-dimethanol to 15 mL of pyridine to obtain solution B. Add solution A to solution B, cool to 0°C and stir for 16 h. After stirring, concentrate to remove the solvent. Extract the residue with chloroform, wash with water and brine, and dry for the next step.

[0046] X2. Add 8 g of fluorene to 40 mL of tetrahydrofuran, mix well, then add dropwise 65 mL of n-butyllithium in n-hexane at -76°C, and continue stirring at -76°C for 2 h to obtain a mixture C; add 12 g of the product in step X1 to 150 mL of tetrahydrofuran, mix well to obtain a solution D; add solution D dropwise to mixture C at -76°C, warm to room temperature after the addition is complete, stir for 16 h, extract with chloroform to obtain an organic phase, and then wash with water, dry, and concentrate to obtain a spirofluorene monomer.

[0047] Example 4 is the same as Example 1, the only difference being that the concentration of the spirofluorene monomer is 0.1 mol / L.

[0048] Example 5 is the same as Example 1, the only difference being that the concentration of the spirofluorene monomer is 0.3 mol / L.

[0049] Test Example The transmittance, refractive index and elongation at break of the cyclic olefin copolymer prepared in the control example and the embodiment were tested. Among them, the transmittance was measured by ultraviolet visible spectrophotometer, and the measuring wavelength was 400~800nm. The refractive index was measured by the Becke line method using an Abbe refractometer, and the measuring wavelength was 623nm. The elongation at break was based on GB / T1040.1-2018 "Determination of Tensile Properties of Plastics Part 1: General Principles", the spline spacing was 20.0mm, the test rate was 5mm / min, and each sample was tested 5 times to take the average value.

[0050] Table 1 Performance test of cycloolefin copolymer

[0051] Experimental protocol Transmittance / % Refractive Index Elongation at break / % Comparative Example 1 90.8 1.522 5.2 Example 1 93.1 1.581 8.1 Example 2 91.2 1.543 6.9 Example 3 90.1 1.529 6.3 Example 4 91.5 1.542 7.0 Example 5 92.2 1.576 6.8

[0052] From the comparison between the reference example 1 and the embodiment, it can be seen that the cycloolefin copolymer synthesized by the spirofluorene-based olefin monomer has better optical and mechanical properties. This may be because in the embodiment, an aromatic group with a high molar refractive index is introduced into the spirofluorene-based olefin monomer, and then polymerized with norbornene and ethylene to obtain a cycloolefin copolymer. Since the fluorene part is perpendicular to the polymer main chain, the free volume fraction around the fluorene part provides high solubility and processability. In terms of optical properties, polarization anisotropy can be offset by the cardo structure, and the spirofluorene part of the vertically oriented polymer main chain can offset the high refractive index in the stretching direction, thereby reducing polarization anisotropy, achieving low birefringence and high refraction, and thus achieving high transmittance. Due to the influence of the high refractive group, a high refractive index cycloolefin copolymer with a certain toughness is obtained, and the large steric hindrance and strong rigid structure of the spirofluorene itself can also bring about the improvement of mechanical properties, thereby further improving the performance of the cycloolefin copolymer. Compared with Examples 2-3, Example 1 has more aromatic rings, a larger molecular weight, and steric hindrance than Examples 2-3 because the (2,7-bis(phenylmethyl)-9H-fluorene used in the combination of the spirofluorene monomer has a larger optical property and mechanical property. It is precisely because of this that when the concentration of the added spirofluorene monomer increases, the mechanical property will increase first and then decrease. Therefore, the performance of Example 1 is the best compared with Examples 4-5.

[0053] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for preparing a cycloolefin copolymer, characterized in that: The steps include: In a nitrogen atmosphere, norbornene and spirofluorene monomers are mixed with a solvent, wherein the concentration of norbornene is 0.2-1 mol / L, and the concentration of spirofluorene monomer is 0.1-0.5 mol / L, and after heating, a mixed solution of the catalyst and the solvent is added, ethylene is passed until the pressure reaches 0.1-0.2 MPa, and the heating is stopped after stirring for 1-2 hours, and ethanol acidified with hydrochloric acid is injected to terminate the reaction, and the product is washed, filtered, and then dried in a vacuum to obtain the cycloolefin copolymer; The method for preparing the spirofluorene-based olefin monomer comprises the following steps: X1, adding 10-20 parts by weight of p-toluenesulfonyl chloride and 0.1-0.5 parts by weight of 4-dimethylaminopyridine to 60-80 parts by weight of pyridine to obtain a solution A, and adding 2-8 parts by weight of 5-norbornene-2,3-dimethanol to 10-20 parts by weight of pyridine to obtain a solution B; Solution A was added to solution B, and the mixture was cooled to 0-5°C and stirred for 12-18 hours. After the stirring was completed, the mixture was concentrated to remove the solvent. The residue was extracted with chloroform, washed with water and brine, and dried for the next step. X2. Add 10-20 parts by weight of 2,7-bis(phenylmethyl)-9H-fluorene to 20-50 parts by weight of tetrahydrofuran, mix well, then add dropwise 50-100 parts by weight of n-butyllithium in n-hexane at -80--70°C, and continue stirring at -80--70°C for 1-2 hours to obtain a mixture C; add 10-20 parts by weight of the product in step X1 to 100-200 parts by weight of tetrahydrofuran, mix well to obtain a solution D; add dropwise solution D to mixture C at -80--70°C, warm to room temperature after the addition is complete, stir for 10-20 hours, extract with chloroform to obtain an organic phase, and then wash with water, dry, and concentrate to obtain a spirofluorene monomer.

2. The method for preparing a cycloolefin copolymer according to claim 1, wherein The molar ratio of the catalyst to norbornene is 1:

110.

3. The method for preparing a cycloolefin copolymer according to claim 1, wherein The solvent is one of n-hexane, cyclohexane, cyclopentane, methylcyclohexane, benzene, toluene and xylene.

4. The method for preparing a cycloolefin copolymer according to claim 1, wherein The heating temperature range is 70-80°C.

5. The method for preparing a cycloolefin copolymer according to claim 1, wherein The catalyst is a metallocene, which is one of Cp2ZrCl2, (Ind)2ZrCl2, rac-[Et(Ind)2]ZrCl2, and rac-[Et(Ind-H4)2]ZrCl2; the catalyst also includes an aluminoxane compound, which is methylaluminoxane or modified methylaluminoxane; the molar ratio of the metallocene to norbornene is 1:1000~4000, and the molar ratio of the metallocene to the aluminoxane compound is 1:

500.

6. The method for preparing a cycloolefin copolymer according to claim 1, wherein The steps include: In a nitrogen atmosphere, norbornene and spirofluorene monomers are mixed with toluene, wherein the concentration of norbornene is 0.8 mol / L, and the concentration of spirofluorene monomer is 0.2 mol / L, and the mixture is heated to 80° C., and a mixed solution of rac-[Et(Ind)2]ZrCl2, methylaluminoxane and toluene is added, wherein the molar ratio of rac-[Et(Ind)2]ZrCl2 to norbornene is 1:3000, and the molar ratio of rac-[Et(Ind)2]ZrCl2 to methylaluminoxane is 1:500, ethylene is introduced until the pressure reaches 0.1 MPa, and the mixture is stirred for 2 h and then heating is stopped. Ethanol acidified with hydrochloric acid is injected to terminate the reaction, and the product is washed, filtered and then dried in vacuum to obtain the cycloolefin copolymer. The method for preparing the spirofluorene-based olefin monomer comprises the following steps: X1. Add 15 g of p-toluenesulfonyl chloride and 0.3 g of 4-dimethylaminopyridine to 70 mL of pyridine to obtain solution A, and add 5 g of 5-norbornene-2,3-dimethanol to 15 mL of pyridine to obtain solution B; add solution A to solution B, cool to 0°C and stir for 16 hours, concentrate to remove the solvent after stirring, extract the residue with chloroform, wash with water and brine, and dry for the next step; X2. Add 16 g of 2,7-bis(phenylmethyl)-9H-fluorene to 40 mL of tetrahydrofuran, mix well, then add dropwise 65 mL of n-butyllithium in n-hexane at -76°C, and continue stirring at -76°C for 2 h to obtain a mixture C; add 12 g of the product in step X1 to 150 mL of tetrahydrofuran, mix well to obtain a solution D; add solution D dropwise to mixture C at -76°C, warm to room temperature after the addition is complete, stir for 16 h, extract with chloroform to obtain an organic phase, and then wash with water, dry, and concentrate to obtain a spirofluorene monomer.

7. A cycloolefin copolymer, characterized in that: Prepared by the method according to any one of claims 1 to 6.

8. Use of the cyclic olefin copolymer as claimed in claim 7 in a virtual reality level head mounted display.