A low phase difference PMMA optical film and a method for manufacturing the same

Abstract

The application discloses a low-phase-difference PMMA optical film and a preparation method thereof, and belongs to the optical film material field. The low-phase-difference PMMA optical film is prepared from raw materials containing the following components by weight: 100 parts of PMMA resin, 6-8 parts of PC resin and 2.5-3.5 parts of a copolymer coated catalyst. The copolymer coated catalyst is prepared by copolymerization and coating of bismaleimide diphenylmethane and acrylate monomers on the surface of an ester exchange catalyst, and the mass ratio of the ester exchange catalyst, the bismaleimide diphenylmethane and the acrylate monomers is 1:(0.3-0.55):(2.2-2.8). The application has the effect of improving the high-temperature resistance of the PMMA film while keeping the PMMA film with low phase difference and high light transmittance.

Description

Technical Field

[0001] This application relates to the field of optical film materials, and in particular to a low phase difference PMMA optical film and its preparation method. Background Technology

[0002] PMMA, or polymethyl methacrylate, is widely used in many fields due to its excellent transparency and good processing properties. Especially in the application of optical films, PMMA has become an important choice for manufacturing various optical elements and devices due to its excellent light transmittance, low phase difference and low cost. It can be used as a key component in projector lenses and various optoelectronic devices.

[0003] One major drawback of PMMA is its poor high-temperature resistance, which limits its application in high-temperature environments. To improve the high-temperature resistance of PMMA films, high-temperature resistant polymers are often blended with PMMA to enhance the film's high-temperature performance. Furthermore, PC (polycarbonate) is a good blending choice to maintain a low phase difference in PMMA films.

[0004] However, due to the poor compatibility between PMMA and PC, the transmittance of PMMA films blended with PC is greatly reduced, affecting their use in the optical field. Summary of the Invention

[0005] In order to improve the high temperature resistance of PMMA film while maintaining a low phase difference and high transmittance, this application provides a low phase difference PMMA optical film and its preparation method.

[0006] Firstly, the low phase difference PMMA optical film provided in this application adopts the following technical solution:

[0007] A low-phase-difference PMMA optical film is prepared from raw materials comprising the following parts by weight:

[0008] 100 parts of PMMA resin;

[0009] 6-8 parts of PC resin;

[0010] 2.5–3.5 parts of the copolymer-coated catalyst;

[0011] The copolymer-coated catalyst is formed by copolymerizing bismaleimide diphenylmethane and acrylate monomers onto the surface of the transesterification catalyst, and the mass ratio of the transesterification catalyst, bismaleimide diphenylmethane and acrylate monomers is 1:(0.3-0.55):(2.2-2.8).

[0012] By adopting the above technical solution, under the action of the ester exchange catalyst, some PMMA resin and PC resin generate a compatible copolymer through ester exchange reaction. The compatible copolymer can improve the compatibility between PMMA resin and PC resin, thereby improving the interfacial bonding force between PMMA resin and PC resin, improving the light transmittance of PMMA film, and improving optical performance.

[0013] By coating the transesterification catalyst with bismaleimide diphenylmethane and acrylate monomers during the copolymerization process, the transesterification reaction can be moderated, and the dispersibility of the transesterification catalyst can be improved. This reduces problems such as heterogeneity or chain segment breakage caused by excessive local transesterification reaction in the blend system. Furthermore, the copolymer has high segment compatibility with PMMA resin and PC resin, which further reduces the surface tension between the two phases and reduces interfacial scattering caused by phase separation. Thus, while maintaining the low phase difference and high light transmittance of the PMMA film, the high temperature resistance of the PMMA film is improved.

[0014] Optionally, the transesterification catalyst includes an organotin catalyst or an inorganic tin catalyst.

[0015] By adopting the above technical solution, tin-based catalysts are effective catalysts for transesterification reactions, promoting transesterification reactions between PMMA resin and PC resin during blending to generate compatible copolymers, thereby improving the compatibility between PMMA resin and PC resin and increasing the light transmittance of PMMA film.

[0016] Optionally, the transesterification catalyst is stannous chloride.

[0017] By adopting the above technical solution, stannous chloride, as a type of tin catalyst, has a good catalytic effect on the transesterification reaction of PMMA resin and PC resin, and is suitable for coating bismaleimide diphenylmethane-acrylate copolymer, which can be uniformly dispersed while gently catalyzing the transesterification reaction.

[0018] Optionally, the acrylate monomer includes one or more of methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate.

[0019] By adopting the above technical solution, the segments of the copolymer formed by the acrylate monomers are similarly compatible with PMMA resin, thereby improving the interfacial compatibility between PMMA resin and PC resin.

[0020] Optionally, the acrylate monomer is selected from propyl acrylate.

[0021] By adopting the above technical solution and using propylene acrylate as the acrylate monomer, the interfacial bonding force of the blend system can be guaranteed, the chain segment flexibility can be effectively improved, and the force-dispersing effect can be played, thereby improving the toughness of the PMMA film.

[0022] Secondly, the method for preparing a low-phase-difference PMMA optical film provided in this application adopts the following technical solution:

[0023] A method for preparing a low-phase-difference PMMA optical film includes the following steps:

[0024] Acrylic ester monomers are dissolved in an organic solvent, heated, and then bismaleimide diphenylmethane is added. After uniform dispersion, an ester exchange catalyst is added, followed by the gradual addition of an initiator. After the reaction is complete, the mixture is filtered, washed, and dried to obtain a copolymer-coated catalyst. PMMA resin, PC resin, and the copolymer-coated catalyst are mixed, and the resulting blend is melted, extruded, plasticized, calendered, and traction-cooled to obtain a PMMA optical film.

[0025] By adopting the above technical solution, the copolymer is coated with the transesterification catalyst under the action of initiating copolymerization, and the PMMA resin and PC resin are blended and compatible by melt extrusion.

[0026] Optionally, in the step of preparing the copolymer-coated catalyst, after heating to 75-85°C, bismaleimide diphenylmethane is added, and after being dispersed evenly, the transesterification catalyst is added. The temperature is then raised to 90-95°C and held for 1-1.5 hours, while the initiator is gradually added. The temperature is then raised to 100-105°C and held for 0.5-1 hours. The heating is then stopped, the temperature is cooled, and the mixture is filtered.

[0027] By adopting the above technical solution, the gradient heating method helps to improve the stability of the copolymer-coated catalyst, and the copolymer and catalyst are less likely to separate during the high-speed mixing process of the blend.

[0028] Optionally, in the step of preparing the copolymer-coated catalyst, the organic solvent includes one or more of benzene, toluene, and xylene.

[0029] Optionally, in the step of preparing the copolymer-coated catalyst, the initiator includes one or both of benzoyl peroxide and azobisisobutyronitrile.

[0030] Optionally, in the step of preparing the PMMA optical film, the mixture is heated to 100–120°C during the mixing process.

[0031] By adopting the above technical solution, heating during the mixing process helps to improve the uniformity of blending.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. In the blend system of this application, under the action of the transesterification catalyst, some PMMA resin and PC resin generate a compatible copolymer through transesterification reaction. The compatible copolymer can improve the compatibility between PMMA resin and PC resin, increase the light transmittance of PMMA film, and the transesterification catalyst is coated with bismaleimide diphenylmethane and acrylate monomer during copolymerization, which can play a role in moderating the transesterification reaction and improving the dispersibility of the transesterification catalyst. This reduces problems such as heterogeneity or chain segment breakage caused by excessive local transesterification reaction in the blend system. In addition, the copolymer has high chain segment compatibility with PMMA resin and PC resin, further reducing the surface tension between the two phases and reducing interfacial scattering caused by phase separation. Thus, while maintaining the low phase difference and high light transmittance of PMMA film, the high temperature resistance of PMMA film is improved.

[0034] 2. This application uses propyl acrylate as the acrylate monomer, which can effectively improve the chain segment flexibility and play a role in dispersing the stress while ensuring the interfacial bonding force of the blend system, thereby improving the toughness of the PMMA film. Detailed Implementation

[0035] The following provides a further detailed description of this application.

[0036] Example 1

[0037] A method for preparing a low-phase-difference PMMA optical film includes the following steps:

[0038] Weigh out 100g of transesterification catalyst, 30g of bismaleimide diphenylmethane, 220g of acrylate monomer, 30g of initiator solution, and 1L of organic solvent.

[0039] Specifically, the transesterification catalyst is stannous chloride; the acrylate monomer is methyl methacrylate; the initiator solution is a toluene solution containing 10 wt% initiator, and the initiator is benzoyl peroxide; the organic solvent is toluene.

[0040] Under nitrogen protection, acrylate monomers were dissolved in an organic solvent and heated to 80°C. Then, bismaleimide diphenylmethane was added and dispersed evenly. After that, transesterification catalyst was added, and the temperature was raised to 90°C and held for 1.5 h. While holding the temperature, an initiator solution was gradually added dropwise. The initiator solution was added dropwise over 0.5 h. Then, the temperature was raised to 100°C and held for 1 h. The heating was then stopped, the temperature was cooled, filtered, washed with toluene, and dried to obtain the copolymer-coated catalyst.

[0041] Weigh out 10 kg of PMMA resin, 0.6 kg of PC resin, and 0.25 kg of copolymer-coated catalyst.

[0042] Specifically, the PMMA resin is Evonik 8N; and the PC resin is Teijin 1250Y.

[0043] PMMA resin, PC resin and copolymer-coated catalyst were added to a mixer and mixed for 30 minutes. During the mixing process, the mixture was heated to 100°C. The resulting blend was then fed into an extruder for melting and extrusion. The extruder temperature was 260°C and the extruder speed was 60 r / min. The extruded film was plasticized, calendered, and traction-cooled to a thickness of 50 μm to obtain a PMMA optical film.

[0044] Example 2

[0045] A method for preparing a low-phase-difference PMMA optical film includes the following steps:

[0046] Weigh out 100g of transesterification catalyst, 55g of bismaleimide diphenylmethane, 280g of acrylate monomer, 35g of initiator solution, and 1L of organic solvent.

[0047] Specifically, the transesterification catalyst is stannous chloride; the acrylate monomer is methyl methacrylate; the initiator solution is a toluene solution containing 10 wt% initiator, and the initiator is benzoyl peroxide; the organic solvent is toluene.

[0048] Under nitrogen protection, acrylate monomers were dissolved in an organic solvent and heated to 80°C. Then, bismaleimide diphenylmethane was added and dispersed evenly. After that, transesterification catalyst was added, and the temperature was raised to 95°C and held for 1 hour. While holding the temperature, an initiator solution was gradually added dropwise. The initiator solution was added dropwise over 0.5 hours. Then, the temperature was raised to 105°C and held for 0.5 hours. The heating was then stopped, the temperature was cooled, filtered, washed with toluene, and dried to obtain the copolymer-coated catalyst.

[0049] Weigh out 10 kg of PMMA resin, 0.8 kg of PC resin, and 0.35 kg of copolymer-coated catalyst.

[0050] Specifically, the PMMA resin is Evonik 8N; and the PC resin is Teijin 1250Y.

[0051] PMMA resin, PC resin and copolymer-coated catalyst were added to a mixer and mixed for 30 minutes. During the mixing process, the mixture was heated to 120°C. The resulting blend was then fed into an extruder for melting and extrusion. The extruder temperature was 260°C and the extruder speed was 60 r / min. The extruded film was plasticized, calendered, and traction-cooled to a thickness of 50 μm to obtain a PMMA optical film.

[0052] Example 3

[0053] A method for preparing a low-phase-difference PMMA optical film includes the following steps:

[0054] Weigh out 100g of transesterification catalyst, 0.5g of bismaleimide diphenylmethane, 2.5g of acrylate monomer, 3.5g of initiator solution, and 1L of organic solvent.

[0055] Specifically, the transesterification catalyst is stannous chloride; the acrylate monomer is methyl methacrylate; the initiator solution is a toluene solution containing 10 wt% initiator, and the initiator is benzoyl peroxide; the organic solvent is toluene.

[0056] Under nitrogen protection, acrylate monomers were dissolved in an organic solvent and heated to 80°C. Then, bismaleimide diphenylmethane was added and dispersed evenly. After that, transesterification catalyst was added, and the temperature was raised to 90°C and held for 1.5 h. While holding the temperature, an initiator solution was gradually added dropwise. The initiator solution was added dropwise over 0.5 h. Then, the temperature was raised to 100°C and held for 1 h. The heating was then stopped, the temperature was cooled, filtered, washed with toluene, and dried to obtain the copolymer-coated catalyst.

[0057] Weigh out 10 kg of PMMA resin, 0.7 kg of PC resin, and 0.29 kg of copolymer-coated catalyst.

[0058] Specifically, the PMMA resin is Evonik 8N; and the PC resin is Teijin 1250Y.

[0059] PMMA resin, PC resin and copolymer-coated catalyst were added to a mixer and mixed for 30 minutes. During the mixing process, the mixture was heated to 100°C. The resulting blend was then fed into an extruder for melting and extrusion. The extruder temperature was 260°C and the extruder speed was 60 r / min. The extruded film was plasticized, calendered, and traction-cooled to a thickness of 50 μm to obtain a PMMA optical film.

[0060] Example 4

[0061] A method for preparing a low phase difference PMMA optical film.

[0062] The difference between this embodiment and Example 3 is that the acrylate monomer is specifically propyl methacrylate.

[0063] Example 5

[0064] A method for preparing a low phase difference PMMA optical film.

[0065] The difference between this embodiment and Embodiment 3 is that the acrylate monomer is specifically ethyl acrylate.

[0066] Example 6

[0067] A method for preparing a low phase difference PMMA optical film.

[0068] The difference between this embodiment and Embodiment 3 is that the acrylate monomer is specifically propyl acrylate.

[0069] Comparative Example 1

[0070] A method for preparing a PMMA optical film includes the following steps:

[0071] Weigh out 10 kg of PMMA resin and 0.7 kg of PC resin.

[0072] Specifically, the PMMA resin is Evonik 8N; and the PC resin is Teijin 1250Y.

[0073] PMMA resin and PC resin were mixed in a mixer for 30 minutes. The mixture was heated to 100°C during the mixing process. The resulting blend was then fed into an extruder for melting and extrusion. The extruder temperature was 260°C and the extruder speed was 60 r / min. The extruded film was plasticized, calendered, and traction cooled to a thickness of 50 μm to obtain a PMMA optical film.

[0074] Comparative Example 2

[0075] A method for preparing a PMMA optical film includes the following steps:

[0076] Weigh out 10 kg of PMMA resin, 0.7 kg of PC resin, and 0.29 kg of catalyst.

[0077] Specifically, the PMMA resin is Evonik 8N; the PC resin is Teijin 1250Y; and the catalyst is stannous chloride.

[0078] PMMA resin, PC resin and catalyst were mixed in a mixer for 30 minutes. The mixture was heated to 100°C during the mixing process. The resulting blend was then fed into an extruder for melting and extrusion. The extruder temperature was 260°C and the extruder speed was 60 r / min. The extruded film was plasticized, calendered, and traction cooled to a thickness of 50 μm to obtain a PMMA optical film.

[0079] Comparative Example 3

[0080] A method for preparing a PMMA optical film includes the following steps:

[0081] Weigh out 100g of transesterification catalyst, 0.5g of styrene, 2.5g of acrylate monomer, 3.5g of initiator solution, and 1L of organic solvent.

[0082] Specifically, the transesterification catalyst is stannous chloride; the acrylate monomer is methyl methacrylate; the initiator solution is a toluene solution containing 10 wt% initiator, and the initiator is benzoyl peroxide; the organic solvent is toluene.

[0083] Under nitrogen protection, acrylate monomers were dissolved in an organic solvent and heated to 80°C. Styrene was then added and dispersed evenly. Transesterification catalyst was then added, and the temperature was raised to 90°C and held for 1.5 hours. While holding the temperature, an initiator solution was gradually added dropwise. The initiator solution was added completely over 0.5 hours. The temperature was then raised to 100°C and held for 1 hour. Heating was then stopped, the catalyst was cooled, filtered, washed with toluene, and dried to obtain the copolymer-coated catalyst.

[0084] Weigh out 10 kg of PMMA resin, 0.7 kg of PC resin, and 0.29 kg of copolymer-coated catalyst.

[0085] Specifically, the PMMA resin is Evonik 8N; and the PC resin is Teijin 1250Y.

[0086] PMMA resin, PC resin and copolymer-coated catalyst were added to a mixer and mixed for 30 minutes. During the mixing process, the mixture was heated to 100°C. The resulting blend was then fed into an extruder for melting and extrusion. The extruder temperature was 260°C and the extruder speed was 60 r / min. The extruded film was plasticized, calendered, and traction-cooled to a thickness of 50 μm to obtain a PMMA optical film.

[0087] Performance testing

[0088] Thermal stability test: The glass transition temperature (Tg) of the PMMA optical film was tested using differential scanning calorimetry. The test procedure included heating each sample from 30℃ to 240℃ under nitrogen protection, holding it at 240℃ for 4 min to eliminate thermal history, then cooling it to 30℃, and then heating it back to 240℃. The heating and cooling rates were both 10℃ / min. The test results are shown in Table 1.

[0089] Transmittance test: The transmittance of the PMMA optical film was tested using a transmittance tester. The test results are shown in Table 1.

[0090] Phase difference: The phase difference of the PMMA optical film was measured using an Axoscan phase difference tester. The test results are shown in Table 1.

[0091] Toughness test: Dumbbell-shaped specimens were prepared according to the composition of PMMA optical film, and the elongation at break was tested using a universal testing machine. The test results are shown in Table 1.

[0092] Table 1

[0093]

[0094] Based on the test analysis in Table 1, compared with the film prepared by directly blending PMMA resin and PC resin in Comparative Example 1, the PMMA optical film in Example 3 has higher light transmittance, higher glass transition temperature and lower phase difference. Therefore, the PMMA optical film has good optical performance and good high temperature resistance.

[0095] Compared with Comparative Example 2, the PMMA optical film of Example 3 has higher light transmittance and a greater advantage in glass transition temperature. This indicates that the coating of the copolymer with the transesterification catalyst can reduce problems such as heterogeneity or chain segment breakage caused by excessive local transesterification reaction in the blend system, thereby improving the high temperature resistance.

[0096] Compared with Comparative Example 3, Example 3 has a higher glass transition temperature and a greater advantage in light transmittance of the PMMA optical film. This indicates that the copolymer is formed by copolymerizing bismaleimide diphenylmethane and acrylate monomers, which has high compatibility with the blend system and further reduces interfacial scattering caused by phase separation, thereby improving the light transmittance of the PMMA optical film.

[0097] Compared with Examples 3, 4 and 5, the PMMA optical film of Example 6 showed a significant improvement in elongation at break, indicating that when propylene acrylate monomers were used in the copolymer, the toughness of the PMMA optical film was improved by increasing the flexibility of the chain segments.

[0098] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A low-phase-difference PMMA optical film, characterized in that: It is prepared from raw materials comprising the following parts by weight: 100 parts of PMMA resin; 6-8 parts of PC resin; 2.5 to 3.5 parts of copolymer-coated catalyst; The copolymer-coated catalyst is formed by copolymerizing bismaleimide diphenylmethane and acrylate monomers onto the surface of the transesterification catalyst, wherein the mass ratio of the transesterification catalyst, bismaleimide diphenylmethane and acrylate monomers is 1:(0.3~0.55):(2.2~2.8). The acrylate monomers include one or more of methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate.

2. The low phase difference PMMA optical film according to claim 1, characterized in that: The transesterification catalyst includes organotin catalysts or inorganic tin catalysts.

3. The low phase difference PMMA optical film according to claim 1, characterized in that: The transesterification catalyst is stannous chloride.

4. The low phase difference PMMA optical film according to claim 1, characterized in that: The acrylate monomer is propyl acrylate.

5. A method for preparing a low-phase-difference PMMA optical film according to any one of claims 1-4, characterized in that: Includes the following steps: The acrylate monomer was dissolved in an organic solvent, heated, and then bismaleimide diphenylmethane was added. After the mixture was dispersed evenly, an transesterification catalyst was added, followed by the gradual addition of an initiator. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the copolymer-coated catalyst. PMMA resin, PC resin and copolymer-coated catalyst are mixed, the resulting blend is melted, extruded, plasticized, calendered and traction-cooled to form a PMMA optical film.

6. The method for preparing a low-phase-difference PMMA optical film according to claim 5, characterized in that: In the step of preparing the copolymer-coated catalyst, after heating to 75~85℃, bismaleimide diphenylmethane is added, and after being dispersed evenly, the transesterification catalyst is added. The temperature is then raised to 90~95℃ and held for 1~1.5h, while the initiator is gradually added. Then the temperature is raised to 100~105℃ and held for 0.5~1h, the heating is stopped, the temperature is cooled, and the mixture is filtered.

7. The method for preparing a low phase difference PMMA optical film according to claim 5, characterized in that: In the step of preparing the copolymer-coated catalyst, the organic solvent includes one or more of benzene, toluene, and xylene.

8. The method for preparing a low phase difference PMMA optical film according to claim 5, characterized in that: In the step of preparing the copolymer-coated catalyst, the initiator includes one or both of benzoyl peroxide and azobisisobutyronitrile.

9. The method for preparing a low-phase-difference PMMA optical film according to claim 5, characterized in that: In the process of preparing PMMA optical film, the mixture is heated to 100~120℃.

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