Multi-layer composite optical film subjected to film blowing and stretching as well as preparation method and application of multi-layer composite optical film

Abstract

The invention provides a blown and stretched multilayer composite optical film as well as a preparation method and application thereof. The multi-layer composite optical film is prepared by adopting a film blowing and stretching process, the production efficiency is relatively high, and the productivity of a single production line is huge. According to the multi-layer composite optical film disclosed by the invention, by combining materials with different refractive indexes, propagation and reflection of light can be accurately controlled, so that the transmissivity is improved, the reflectivity is reduced, and the light is more uniformly distributed. Therefore, the multi-layer composite optical film has important application in the fields of display technology, spectacle lenses, photographic equipment and the like.

Description

Technical Field

[0001] This invention belongs to the field of composite materials, specifically relating to a blown film stretching multilayer composite optical film, its preparation method, and its application. Background Technology

[0002] Cyclic olefin resin (COC / COP) films are amorphous transparent polymer materials with a cyclic olefin structure, and have been widely used in various fields in recent years. The applications of cyclic olefin resin films are extensive, including: Optics: Due to their excellent optical properties, such as low birefringence and good refractive index stability, cyclic olefin resin films are widely used in the manufacture of optical components such as cameras, printers, optical reading heads, and mirrors. Medical: The transparency, high shielding properties, and low impurity content of cyclic olefin resin films make them ideal for medical devices and related applications. For example, they can be used to manufacture medical devices and medical packaging, ensuring product safety and purity. Packaging: The excellent airtightness of cyclic olefin resin films, as well as their balanced performance in water vapor barrier, O2, and CO2 barrier rates, makes them promising for wide application in the packaging field. Other fields: In addition, cyclic olefin resin films can also be used in high-frequency connectors, antenna substrates, and other fields, utilizing their low permittivity and low dielectric loss characteristics.

[0003] Zeon Optical Films of Japan primarily employs uniaxial or biaxial stretching methods to prepare cyclic olefin resin films, resulting in films with high transmittance and high strength. However, the casting and biaxial stretching equipment is expensive and difficult to operate, increasing the processing cost and technical requirements of cyclic olefin resin films, thus hindering their widespread adoption and application. Furthermore, single-layer cyclic olefin resin films cannot meet the requirements of high-end applications in terms of transmittance and refractive index. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A method for preparing a multilayer composite optical film, wherein the preparation method is a blown film stretching method, and the preparation method specifically includes: preparing raw materials according to the film structure of the multilayer composite optical film, and preparing the multilayer composite optical film by multilayer co-extrusion, blown film stretching.

[0006] According to an embodiment of the present invention, the raw materials include a first raw material and a second raw material, wherein the first raw material is selected from cyclic olefin polymers having the structure shown in Formula 1, and the second raw material is selected from copolymers of ethylene and cyclic olefins having the structure shown in Formula 2.

[0007]

[0008] According to an embodiment of the present invention, in formulas 1 and 2, R1, R2, R3, and R4 may be the same or different, and are independently selected from hydrogen, C, and C. 1-10 Alkyl groups (e.g., at least one of methyl, n-propyl, and isopropyl);

[0009] m, n, and p can be the same or different, and can be selected independently from 1 to 1000, for example, 10, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900.

[0010] According to an embodiment of the present invention, the raw material may optionally include a third raw material selected from cyclic olefin polymers having the structure shown in Formula 1 or copolymers of ethylene and cyclic olefins having the structure shown in Formula 2.

[0011] According to an embodiment of the present invention, the ratio of the total amount of the cyclic olefin polymer to the total amount of the copolymer of ethylene and cyclic olefins in the raw materials is not specifically limited, for example, 10-90:10-90, preferably 20-80:20-80, for example 25:75, 30:70, 35:65, 40:55, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25.

[0012] According to an embodiment of the present invention, the first raw material is used to prepare layer A; the second raw material is used to prepare layer B; and the third raw material is used to prepare layer C.

[0013] According to an embodiment of the present invention, the multilayer co-extrusion can be carried out using methods known in the art, and no specific limitation is made in the present invention. For example, a melt extrusion device known in the art can be used.

[0014] According to an embodiment of the present invention, the temperature for multi-layer co-extrusion can be selected from temperatures known in the art, for example, an extrusion temperature of 150-260°C, preferably 180-250°C. Preferably, during multi-layer co-extrusion, the die temperature of the extruder is 190-240°C.

[0015] According to an embodiment of the present invention, a melt having the film structure is obtained through the multilayer co-extrusion.

[0016] According to an embodiment of the present invention, the melt further needs to be cooled. Preferably, the cooling can be air cooling. Exemplarily, air cooling refers to cooling using a gas (such as air).

[0017] According to an embodiment of the present invention, the air-cooling temperature is 15-30℃, preferably 20-25℃.

[0018] According to an embodiment of the present invention, the blown film stretching refers to: introducing a certain gas into the interior of the melt to inflate the melt, thereby achieving transverse stretching; subsequently, longitudinal stretching is performed. In the present invention, longitudinal refers to the direction along the film extrusion process, and transverse refers to the direction perpendicular to the film extrusion process.

[0019] According to an embodiment of the present invention, the blow-up ratio of the blown film stretching is 2-20, for example, 5, 10, or 15. In this invention, the blow-up ratio refers to the ratio of the maximum diameter of the blown film to the maximum diameter of the melt.

[0020] According to an embodiment of the present invention, the longitudinal stretching ratio is 3-30 times, preferably 5-20 times, for example 10 times or 15 times.

[0021] According to an embodiment of the present invention, the lateral stretching ratio is the blow-up ratio.

[0022] According to an embodiment of the present invention, the ratio of the transverse stretch ratio to the longitudinal stretch ratio is 1-5:1-5, for example, 1:1, 1:2, 1:3, 1:4, 1:5, 2:1, 3:1, 4:1, 5:1.

[0023] According to an embodiment of the present invention, the difference T1-Tg between the stretching temperature T1 and the highest glass transition temperature Tg' in the raw material is -10°C to 30°C, preferably 0°C to 30°C, for example 10°C or 20°C.

[0024] According to an embodiment of the present invention, after the blown film stretching is completed, a further shaping process is performed. Preferably, the shaping refers to heat treatment using a heat-setting roller. Further, the shaping temperature is 100-140°C, preferably 110-120°C. In this invention, shaping can eliminate the internal stress of the film and reduce the longitudinal shrinkage rate.

[0025] According to an embodiment of the present invention, after the blown film stretching is completed, the multilayer composite optical film can be subjected to secondary cooling. Preferably, the secondary cooling can be performed using methods known in the art, and no specific limitation is made in this invention.

[0026] The present invention also provides a multilayer composite optical film prepared by the above method.

[0027] According to an embodiment of the present invention, the multilayer composite optical film includes at least layer A and layer B, wherein the material of layer A comprises a cyclic olefin polymer having the structure shown in Formula 1, and the material of layer B comprises a copolymer of ethylene and cyclic olefin having the structure shown in Formula 2;

[0028]

[0029] In Equations 1 and 2, R1, R2, R3, and R4 may be the same or different, and are independently selected from hydrogen and C. 1-10 Alkyl groups (e.g., at least one of methyl, n-propyl, and isopropyl);

[0030] m, n, and p can be the same or different, and can be selected independently from 1 to 1000, for example, 10, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900.

[0031] According to an embodiment of the present invention, the glass transition temperature (Tg) of the cyclic olefin polymer is in the range of 80-200°C, preferably in the range of 100-180°C, for example, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, or 170°C.

[0032] According to an embodiment of the present invention, the glass transition temperature (Tg) of the copolymer of ethylene and cyclic olefins is 80-200°C, preferably 100-180°C, for example 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, or 170°C.

[0033] According to an embodiment of the present invention, the Tg difference between the cyclic olefin polymer and the copolymer of ethylene and cyclic olefins is no more than 30°C, preferably no more than 20°C.

[0034] According to an embodiment of the present invention, the refractive index of the cyclic olefin polymer is between 1.45 and 1.80, for example, 1.5, 1.6, or 1.7.

[0035] According to an embodiment of the present invention, the refractive index of the copolymer of ethylene and cyclic olefins is between 1.45 and 1.80, for example, 1.5, 1.6, or 1.7.

[0036] According to an embodiment of the present invention, the refractive index difference between the cyclic olefin polymer and the copolymer of ethylene and cyclic olefin is no more than 0.5, preferably no more than 0.2, for example no more than 0.1.

[0037] According to an embodiment of the present invention, the cyclic olefin polymer is selected from at least one of Zeonex K26R, K22R, E48R, F52R, T62R, 330R and 480R from Zeon Corporation of Japan.

[0038] According to an embodiment of the present invention, the copolymer of ethylene and cyclic olefins is preferably a copolymer of ethylene and norbornene, for example, including but not limited to at least one of TOPAS 5013F, TOPAS 6013F, TOPAS 7010F, TOPAS 8007F, and TOPAS 9506F from Japan.

[0039] According to a preferred embodiment of the present invention, the multilayer composite optical film further includes a C layer, the C layer structure of which may be disposed on the surface of the A layer or the B layer. Preferably, the material of the C layer may be selected from cyclic olefin polymers having the structure shown in Formula 1 or copolymers of ethylene and cyclic olefins having the structure shown in Formula 2.

[0040] According to a preferred embodiment of the present invention, the layer structure of the multilayer composite optical film refers to the structure from top to bottom.

[0041] According to a preferred embodiment of the present invention, the multilayer composite optical film has a layer A and a layer B.

[0042] According to a preferred embodiment of the present invention, the multilayer composite optical film has a layer A, a layer B, and a layer C, wherein the material of layer A is the same as the material of layer C, or the material of layer B is the same as the material of layer C.

[0043] According to a preferred embodiment of the present invention, the multilayer composite optical film has a layer structure of layer C, layer A, and layer B, wherein the material of layer A is the same as the material of layer C, or the material of layer B is the same as the material of layer C.

[0044] According to an embodiment of the present invention, the total thickness of the multilayer composite optical film is 10-50 micrometers, preferably 10-30 micrometers, for example 15 micrometers, 20 micrometers, or 25 micrometers.

[0045] According to an embodiment of the present invention, in the multilayer composite optical film, the ratio of the total thickness of the cyclic olefin polymer layer to the total thickness of the copolymer layer of ethylene and cyclic olefin can be 10-90:10-90, preferably 20-80:20-80, for example 25:75, 30:70, 35:65, 40:55, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25.

[0046] According to an embodiment of the present invention, the multilayer composite optical film has a tensile strength of 30-60 MN·m in the longitudinal and / or transverse directions. -2 For example, 35MN·m -2 40MN·m -2 50MN·m -2 55MN·m -2 .

[0047] According to an embodiment of the present invention, the multilayer composite optical film exhibits thermal deformation of less than 1% in the longitudinal and / or transverse directions, for example, 0.5%.

[0048] According to an embodiment of the present invention, the water absorption rate of the multilayer composite optical film is less than 0.5%, for example, 0.1%, 0.2%, 0.3%, or 0.4%.

[0049] According to an embodiment of the present invention, the transmittance of the multilayer composite optical film is not less than 91%, for example, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%.

[0050] According to an embodiment of the present invention, the refractive index of the multilayer composite optical film is 1.50-1.60.

[0051] The present invention also provides uses of the above-mentioned multilayer composite optical film in the optical field (e.g., display technology, eyeglass lenses and photographic equipment), such as in polarizers.

[0052] A polarizer comprising at least the aforementioned multilayer composite optical film.

[0053] The beneficial effects of this invention are:

[0054] Compared to single-layer COP films, the multilayer composite optical film provided by this invention has the following advantages:

[0055] (1) Higher optical performance: By combining materials with different refractive indices, the multilayer composite optical film of the present invention can precisely control the propagation and reflection of light, thereby improving transmittance and reducing reflectance, resulting in a more uniform distribution of light. Therefore, the multilayer composite optical film of the present invention has important applications in display technology, eyeglass lenses, and photographic equipment.

[0056] (2) Greater design flexibility: The design of multilayer composite films can be customized according to specific needs. By adjusting the combination of materials and thicknesses of each layer, optical composite films with both high light transmittance and high refractive index can be obtained, thereby achieving different optical effects and functions.

[0057] (3) The cost of blown film equipment is relatively low, which makes it affordable for small and medium-sized enterprises and relatively easy to introduce into production lines. Moreover, the production efficiency of blown film process is usually high because blown film machines can produce films continuously, and the capacity of a single production line is huge.

[0058] Terminology Definitions and Explanations

[0059] The term "C 1-10 "Alkyl" should be understood as representing a straight-chain or branched saturated monovalent hydrocarbon group having 1 to 10 carbon atoms. For example, "C 1-10 "alkyl" indicates a straight-chain or branched alkyl group having 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms, preferably "C". 1-8 Alkyl or C 1-6 Alkyl group. "C" 1-8 "Alkyl" refers to straight-chain and branched alkyl groups having 1, 2, 3, 4, 5, 6, 7, or 8 carbon atoms.1-6 "Alkyl" means a straight-chain or branched alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms. The alkyl group is, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl, or 1,2-dimethylbutyl, or their isomers. Detailed Implementation

[0060] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0061] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0062] Example 1:

[0063] The multilayer composite optical film in this embodiment has the following structure from top to bottom: layer A and layer B, with thicknesses of 8μm and 8μm respectively; where layer A is Zeonex 480R resin and layer B is TOPAS 6013F resin.

[0064] The specific method for preparing the multilayer composite optical film in this embodiment is as follows:

[0065] Using a two-layer co-extrusion equipment, the resins of layer A and layer B are extruded in equal proportions. The resulting molten resin extruded preform (i.e., melt) is cooled by room temperature air and pulled upwards. Air is introduced into the melt to inflate it, with an inflation ratio of 6. The traction roller speed ratio and the traction roller linear speed are adjusted to make the longitudinal stretch ratio 6 times (i.e., the ratio of the traction roller linear speed to the extruded preform linear speed). Then, it enters the heat setting roller at a temperature of 110°C, and then enters the cooling roller at a temperature of 30°C. A multilayer composite optical film with a thickness of 16±1 micrometers is prepared. The test data are listed in Table 2.

[0066] Example 2:

[0067] The multilayer composite optical film in this embodiment has the following structure from top to bottom: layer A and layer B, with thicknesses of 6 μm and 10 μm, respectively; where layer A is Zeonex 480R resin and layer B is TOPAS.

[0068] 6013F resin.

[0069] The specific method for preparing the multilayer composite optical film in this embodiment is as follows:

[0070] Using a two-layer co-extrusion equipment, the resins of layer A and layer B are extruded at a ratio of 6:10. The co-extruded molten resin preform (i.e., melt) is cooled by room temperature air and pulled upward. Air is introduced into the melt for inflation, with an inflation ratio of 5. The speed ratio of the traction rollers is adjusted, and the linear speed of the traction rollers is adjusted to make the longitudinal stretch ratio 7 times. Then it enters the heat setting roller at a temperature of 110°C, and then enters the cooling roller at a temperature of 30°C. A multilayer composite optical film with a thickness of 16±1 micrometers is prepared. Its test data are listed in Table 2.

[0071] Comparative Example 1:

[0072] The preparation method of the single-layer optical film is as follows: Zeonex 480R resin is used, and a single-layer extrusion device is used. The molten resin is cooled by room temperature air, pulled upward, and internally inflated with an inflation ratio of 6. The speed ratio of the traction roller is adjusted, and the linear speed of the traction roller is adjusted so that the longitudinal stretch ratio is 6 times (the ratio of the linear speed of the traction roller to the linear speed of the extruded film). Then it enters the heat setting roller with a roller temperature of 110°C, and then enters the cooling roller with a roller temperature of 30°C. A multilayer composite optical film with a thickness of 16±1 micrometers is prepared. The test data are listed in Table 2.

[0073] Example 3:

[0074] The multilayer composite optical film in this embodiment has the following structure from top to bottom: layer A, layer B, and layer C, with thicknesses of 4μm, 10μm, and 4μm, respectively; where layer A and layer C are Zeonex 480R resin, and layer B is TOPAS 6013F resin.

[0075] The specific method for preparing the multilayer composite optical film in this embodiment is as follows:

[0076] Using a three-layer co-extrusion equipment, the resins of layers A, B, and C are extruded in a ratio of 4:10:4. The co-extruded molten resin preform (i.e., melt) is cooled by room temperature air and pulled upward. Air is introduced into the melt for inflation, with an inflation ratio of 6. The speed ratio of the traction rollers is adjusted, and the linear speed of the traction rollers is adjusted to make the longitudinal stretch ratio 6 times. The film then enters the heat setting roller at a temperature of 110°C, and then enters the cooling roller at a temperature of 30°C. A multilayer composite optical film with a thickness of 18±1 micrometers is prepared. Its test data are listed in Table 2.

[0077] Example 4:

[0078] The multilayer composite optical film in this embodiment has the following structure from top to bottom: layer C, layer A, and layer B, with thicknesses of 6μm, 4μm, and 6μm, respectively; where layer A is Zeonex 480R resin, and layers B and C are TOPAS 6013F resin.

[0079] The specific method for preparing the multilayer composite optical film in this embodiment is as follows:

[0080] Using a three-layer co-extrusion equipment, the resins of layers C, A, and B are extruded in a ratio of 6:4:6. The co-extruded molten resin preform (i.e., melt) is cooled by room temperature air and pulled upward. Air is introduced into the melt for inflation, with an inflation ratio of 6. The speed ratio of the traction rollers is adjusted, and the linear speed of the traction rollers is adjusted to make the longitudinal stretch ratio 6 times. Then it enters the heat setting roller at a temperature of 110°C, and then enters the cooling roller at a temperature of 30°C. A multilayer composite optical film with a thickness of 16±1 micrometers is prepared. Its test data are listed in Table 2.

[0081] Table 2 Performance results of composite optical films

[0082]

[0083] The exemplary embodiments of the present invention have been described above. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a multilayer composite optical film, characterized in that, The preparation method is a blown film stretching method, which specifically includes: preparing raw materials according to the film structure of the multilayer composite optical film, and preparing the multilayer composite optical film by multilayer co-extrusion, blown film stretching, and other processes.

2. The preparation method according to claim 1, characterized in that, The raw materials include a first raw material and a second raw material, wherein the first raw material is selected from cyclic olefin polymers having the structure shown in Formula 1, and the second raw material is selected from copolymers of ethylene and cyclic olefins having the structure shown in Formula 2. Preferably, in Formulas 1 and 2, R1, R2, R3, and R4 may be the same or different, and are independently selected from hydrogen, C, and C. 1-10 alkyl; m, n, and p can be the same or different, and are selected independently from 1 to 1000. Preferably, the raw material may also optionally include a third raw material selected from cyclic olefin polymers having the structure shown in Formula 1 or copolymers of ethylene and cyclic olefins having the structure shown in Formula 2. Preferably, the first raw material is used to prepare layer A; the second raw material is used to prepare layer B; and the third raw material is used to prepare layer C.

3. The preparation method according to claim 1 or 2, characterized in that, The extrusion temperature for multi-layer co-extrusion is 150-260℃. Preferably, the melt having the film structure is obtained through the multi-layer co-extrusion. Preferably, the melt also needs to be cooled. Preferably, the cooling is performed by air cooling. Preferably, the air-cooling temperature is 15-30℃. Preferably, the blown film stretching refers to: introducing a certain gas into the film of the melt to inflate the melt, thereby achieving transverse stretching; and then performing longitudinal stretching in the longitudinal direction.

4. The preparation method according to any one of claims 1-3, characterized in that, The blow-up ratio of the blown film stretching is 2-20. Preferably, the longitudinal stretching ratio is 3-30 times. Preferably, the lateral stretching ratio is the blow-up ratio. Preferably, the ratio of the transverse stretching ratio to the longitudinal stretching ratio is 1-5:1-5. Preferably, the difference between the stretching temperature T1 and the highest glass transition temperature Tg' in the raw material, T1-Tg, is between -10°C and 30°C. Preferably, after the blown film stretching is completed, it is further shaped. Preferably, after the blown film stretching is completed, the multilayer composite optical film is further cooled.

5. The preparation method according to any one of claims 1-4 yields a multilayer composite optical film.

6. The multilayer composite optical film according to claim 5, characterized in that, The multilayer composite optical film includes at least layer A and layer B, wherein the material of layer A includes a cyclic olefin polymer having the structure shown in Formula 1, and the material of layer B includes a copolymer of ethylene and cyclic olefin having the structure shown in Formula 2. In Equations 1 and 2, R1, R2, R3, and R4 may be the same or different, and are independently selected from hydrogen and C. 1-10 alkyl; m, n, and p can be the same or different, and are selected independently from 1 to 1000. Preferably, the glass transition temperature (Tg) of the cyclic olefin polymer is between 80 and 200°C. Preferably, the glass transition temperature (Tg) of the copolymer of ethylene and cyclic olefins is between 80 and 200°C. Preferably, the Tg difference between the cyclic olefin polymer and the copolymer of ethylene and cyclic olefins does not exceed 30°C. Preferably, the refractive index of the cyclic olefin polymer is between 1.45 and 1.

80. Preferably, the refractive index of the copolymer of ethylene and cyclic olefins is between 1.45 and 1.

80. Preferably, the refractive index difference between the cyclic olefin polymer and the copolymer of ethylene and cyclic olefins is no more than 0.

5.

7. The multilayer composite optical film according to claim 5 or 6, characterized in that, The cyclic olefin polymer is selected from at least one of Zeonex K26R, K22R, E48R, F52R, T62R, 330R and 480R from Zeon Corporation of Japan. Preferably, the copolymer of ethylene and cyclic olefins is a copolymer of ethylene and norbornene, including but not limited to at least one of TOPAS 5013F, TOPAS 6013F, TOPAS 7010F, TOPAS 8007F, and TOPAS 9506F from Japan. Preferably, the multilayer composite optical film further includes a C layer, which can be disposed on the surface of the A layer or the B layer. Preferably, the material of the C layer can be selected from cyclic olefin polymers having the structure shown in Formula 1 or copolymers of ethylene and cyclic olefins having the structure shown in Formula 2.

8. The multilayer composite optical film according to any one of claims 5-7, characterized in that, The total thickness of the multilayer composite optical film is 10-50 micrometers. Preferably, the multilayer composite optical film has a tensile strength of 30-60 MN·m in the longitudinal and / or transverse directions. -2 . Preferably, the multilayer composite optical film exhibits thermal deformation of less than 1% in the longitudinal and / or transverse directions. Preferably, the water absorption rate of the multilayer composite optical film is less than 0.5%. Preferably, the transmittance of the multilayer composite optical film is not less than 91%. Preferably, the refractive index of the multilayer composite optical film is 1.50-1.

60.

9. Use of the multilayer composite optical film according to any one of claims 5-8 in the field of optics.

10. A polarizer, said polarizer comprising at least the multilayer composite optical film as described in any one of claims 5-8.

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