Low-precipitation optical film

Abstract

The utility model discloses a low-precipitation optical film, comprising a core layer having a first surface and a second surface opposite to each other along the film thickness; the high-temperature-resistant surface layers are arranged in a double-layer mode and arranged on the first surface and the second surface; the high-temperature-resistant transition layer is clamped between the core layer and the at least one high-temperature-resistant surface layer; and the intrinsic viscosity of each layer from the core layer to the high-temperature-resistant surface layer is gradually increased. The low-precipitation optical film is reasonable in structure, the optical film is prepared by setting that the intrinsic viscosity of the polyester material is gradually increased from the core layer to the surface layer and co-extruding the polyester material, and the polyester with higher intrinsic viscosity has a longer molecular chain, so that the mechanical strength and the thermal stability of the film are improved, the breakage of the chain and the generation of low-molecular-weight substances are reduced, and the yield of the film is improved. The compact surface layer obstructs precipitation of low molecular weight substances of the core layer, so that the high temperature resistance and the surface precipitation problem of the optical film are optimized, the problem that the surface of the optical film is uneven due to uneven thickness is solved, and the problems of incompatibility and layering caused by compounding of different high temperature resistant materials are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of membranes, in particular to a low-precipitation optical film. Background Art

[0002] Polyethylene terephthalate is a commonly used raw material for optical films. The optical film is made into a thick sheet by an extrusion method and then stretched. During its production and preparation process, the processing technology will cause the precipitation of low-molecular-weight substances. The main reasons are that the use of recycled materials will promote the generation of low-molecular-weight chain segments, and the high-temperature extrusion of the extruder will cause the molecular chains of polyester chips to break and generate low-molecular-weight chain segments. And in subsequent surface corona, heat treatment, etc., low-molecular-weight substances migrate to the film surface, which will cause the finished film to turn white and blurred, affecting the application of the optical film.

[0003] Therefore, it is necessary to improve the optical film in the prior art. Summary of the Utility Model

[0004] The purpose of the utility model is to overcome the defects existing in the prior art and provide a low-precipitation optical film. The optical film is made by co-extrusion with the characteristic viscosity of the polyester material gradually increasing from the core layer to the surface layer. The polyester with a higher characteristic viscosity has a longer molecular chain, thereby improving the mechanical strength and thermal stability of the film, reducing the breakage of chains and the generation of low-molecular-weight substances. The dense surface layer blocks the precipitation of low-molecular-weight substances in the core layer, not only optimizing the high-temperature resistance performance and surface precipitation problem of the optical film, overcoming the problem of uneven thickness leading to unevenness on the surface of the optical film, but also overcoming the problem of incompatibility and delamination caused by the combination of different high-temperature-resistant materials.

[0005] To achieve the above technical effects, the technical solution of the utility model is: a low-precipitation optical film, which is a polyester co-extrusion film, including:

[0006] A core layer having a first surface and a second surface opposite to each other along the film thickness;

[0007] A high-temperature-resistant surface layer, arranged in a double layer, respectively arranged on the first surface and the second surface;

[0008] A high-temperature-resistant transition layer, sandwiched between the core layer and at least one high-temperature-resistant surface layer;

[0009] The characteristic viscosity of each layer from the core layer to the high-temperature-resistant surface layer gradually increases.

[0010] The preferred technical solution is that the core layer includes at least one recycled material layer stacked in sequence along the layer thickness, and the recycled material layer is connected to the high-temperature-resistant transition layer or the high-temperature-resistant surface layer through a compatibilizing layer.

[0011] Preferably, the recycled material of the recycled material layer is one of PET, APET and PETG; the compatibilizing layer is a polyester containing a polyester-polyether block copolymer or a polyester containing a polyester-polysiloxane block copolymer.

[0012] Preferably, the high-temperature resistant transition layer is a polyester containing aluminum trioxide.

[0013] Preferably, at least one surface of the high-temperature resistant surface layer away from the core layer is provided with a high-temperature resistant coating.

[0014] Preferably, the high-temperature resistant coating is an epoxy-modified polyurethane coating.

[0015] Preferably, the thickness ratio of the high-temperature resistant surface layer to the core layer is (10~15):(60~80).

[0016] The advantages and beneficial effects of the present utility model are as follows:

[0017] The structure of the low-bleed optical film is reasonable. The optical film is prepared by co-extrusion with the intrinsic viscosity of the polyester material gradually increasing from the core layer to the surface layer. The polyester with a higher intrinsic viscosity has a longer molecular chain, thereby improving the mechanical strength and thermal stability of the film, reducing the breakage of the chain and the generation of low-molecular-weight substances. The dense surface layer blocks the bleeding of low-molecular-weight substances from the core layer, not only optimizing the high-temperature resistance performance and surface bleeding problem of the optical film, overcoming the problem of uneven surface of the optical film caused by uneven thickness, but also overcoming the problem of incompatibility and delamination caused by the lamination of different high-temperature resistant materials. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of Embodiment 1 of the low-bleed optical film of the present utility model;

[0019] Figure 2 is a schematic structural diagram of Embodiment 2 of the low-bleed optical film of the present utility model.

[0020] In the figure: 1, core layer; 2, high-temperature resistant surface layer; 3, high-temperature resistant transition layer; 4, high-temperature resistant coating; 10, recycled material layer; 11, compatibilizing layer. Detailed Embodiments

[0021] The following combines the drawings and embodiments to further describe the specific embodiments of the present utility model. The following embodiments are only used to more clearly illustrate the technical solutions of the present utility model and cannot be used to limit the protection scope of the present utility model.

[0022] The "surface layer" is based on the normal use state of the low-precipitation optical film. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0023] In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0024] The low-precipitation optical film disclosed by the present invention is a polyester co-extruded film, including a core layer 1, a high-temperature resistant surface layer 2, and a high-temperature resistant transition layer 3. The core layer 1 has a first surface (not labeled) and a second surface (not labeled) opposite to each other along the film thickness; the high-temperature resistant surface layer 2 is arranged in a double layer, and the high-temperature resistant surface layer 2 is respectively arranged on the first surface and the second surface; the intrinsic viscosity of each layer from the core layer 1 to the high-temperature resistant surface layer 2 gradually increases.

[0025] The optical film is prepared by co-extrusion with the intrinsic viscosity of the polyester material gradually increasing from the core layer to the surface layer. The polyester with a higher intrinsic viscosity has a longer molecular chain, thereby improving the mechanical strength and thermal stability of the film, reducing the breakage of the chain and the generation of low-molecular-weight substances. The dense surface layer blocks the precipitation of low-molecular-weight substances in the core layer, not only optimizing the high-temperature resistance performance and surface precipitation problem of the optical film, overcoming the problem of uneven surface of the optical film caused by uneven thickness, but also overcoming the problem of incompatibility and delamination caused by the lamination of different high-temperature resistant materials.

[0026] In some embodiments, the high-temperature resistant transition layer 3 is sandwiched between one high-temperature resistant surface layer 2 and the core layer 1.

[0027] In other embodiments, the high-temperature resistant transition layer 3 is sandwiched between the high-temperature resistant surface layer 2 and the core layer 1. The optical film with a symmetric structure has better mechanical properties and high-temperature resistance, and better processing stability.

[0028] Among them, the high-temperature resistant transition layer 3 is a polyester containing aluminum trioxide. To improve the mixing uniformity of aluminum trioxide in the polyester, aluminum trioxide with a particle size of 0.5 - 1.5 μm is preferably used; further, the aluminum trioxide is also modified by a coupling agent to improve its compatibility in the polyester. Adding aluminum trioxide to the polyester has high thermal stability, which can improve the dimensional stability and mechanical properties of the film in a high-temperature environment; it can also enhance the barrier performance, effectively preventing oxygen, water vapor, and other gases from passing through the film and prolonging the usability of the packaged material; by adjusting the particle size of aluminum oxide, the transparency and gloss of the film can be improved, and at the same time, the uniformity of the film can be improved and the haze can be reduced; it can improve the tensile strength and tear strength of the film, making it more durable.

[0029] In some embodiments, the core layer 1 includes at least one recycled material layer 10 stacked in sequence along the layer thickness, and the recycled material layer 10 is connected to the high-temperature resistant transition layer 3 or the high-temperature resistant surface layer 2 through a compatibilizing layer 11. Further, the recycled material of the recycled material layer 10 is one of PET, APET, and PETG; the compatibilizing layer 11 is a polyester containing a polyester-polyether block copolymer or a polyester containing a polyester-polysiloxane block copolymer.

[0030] Among them, to improve the toughness and mechanical properties of the optical film, as well as the compatibility and stability between layers, the raw material of the recycled material layer 10 includes 30% - 50% recycled material and 50% - 70% mixed material, and the material of the mixed material is polyester, which is the same as the material of the compatibilizing layer 11. The polyether part of the polyester-polyether block copolymer imparts good softness and elasticity to the material; the polyether chain segment helps to improve the low-temperature performance of the material, enabling it to remain flexible at low temperatures; the polyether chain segment can improve the processing performance of the material, such as improving fluidity and plasticity. The polysiloxane in the polyester-polysiloxane block copolymer has excellent heat resistance and can maintain stable performance at high temperatures; the polysiloxane chain segment imparts good flexibility to the material, especially maintaining good elasticity even under low-temperature conditions; the polysiloxane chain segment helps to improve the anti-aging performance of the material and extend its service life.

[0031] Mixing different materials changes the surface energy of the polyester, and through the compatibilizing layer 11, the connection firmness between the recycled material layer 10 and the high-temperature resistant transition layer 3 or the high-temperature resistant surface layer 2 is improved, that is, the adhesion between layers is improved through the compatibilizing layer 11; it also effectively improves the problem that the hardness of the optical film is too large due to the gradual increase in the intrinsic viscosity of the polyester.

[0032] On the surface of at least one heat-resistant surface layer 2 away from the core layer 1, a heat-resistant coating 4 is provided. Further, the heat-resistant coating 4 is an epoxy-modified polyurethane coating, and the epoxy-modified polyurethane coating has the following advantages: Epoxy resin itself has strong adhesion, and the modified polyurethane coating can better adhere to a variety of substrates; it has excellent chemical corrosion resistance and can resist the erosion of a variety of acids, alkalis, solvents, and other corrosive chemicals; the surface of the coating is hard and wear-resistant, and can effectively resist scratching and abrasion; it usually has good high and low temperature resistance and is suitable for protection in extreme temperature environments; the coating is dense, not only has good waterproof and moisture-proof properties and is suitable for anti-corrosion protection in humid environments, but also further prevents the precipitation of low molecular weight substances to the surface.

[0033] The total film thickness of the optical film is 50 - 150 μm, and the thickness ratio of the heat-resistant surface layer 2, the heat-resistant transition layer 3, and the core layer 1 is (10 - 15):(15 - 20):(60 - 80). The layer thickness of the heat-resistant coating 4 is 5 - 10 μm.

[0034] Example 1

[0035] As Figure 1 shown, the low-precipitation optical film of Example 1 is a polyester coextrusion film, including a core layer 1, a heat-resistant surface layer 2, and a heat-resistant transition layer 3. The core layer 1 has a first surface (not labeled) and a second surface (not labeled) opposite to each other along the film thickness; the heat-resistant surface layer 2 is arranged in a double layer, and the heat-resistant surface layer 2 is respectively arranged on the first surface and the second surface; the intrinsic viscosity of each layer from the core layer 1 to the heat-resistant surface layer 2 gradually increases. A heat-resistant transition layer 3 is interposed between the heat-resistant surface layer 2 and the core layer 1. The optical film with a symmetric structure has better mechanical properties and heat resistance, and better processing stability. The material of the core layer 1 is polyester and does not contain recycled materials.

[0036] Among them, the heat-resistant transition layer 3 is a polyester containing aluminum oxide, and a heat-resistant coating 4 is provided on the surface of one heat-resistant surface layer 2 away from the core layer 1.

[0037] Example 2

[0038] As Figure 2 shown, Example 2 is based on Example 1, and the difference is that the core layer 1 is a laminated structure of a compatibilizer layer 11 / recycled material layer 10 / compatibilizer layer 11, that is, the recycled material layer 10 is connected to the heat-resistant transition layer 3 through the compatibilizer layer 11. Through the sequential arrangement of the compatibilizer layer 11, the heat-resistant transition layer 3, and the heat-resistant surface layer 2, not only the mechanical properties of the optical film are optimized, but also the problem of precipitation of low molecular weight substances from the recycled materials is reduced.

[0039] The above are only the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present utility model, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present utility model.

Claims

1. A low precipitation optical film, which is a polyester co-extruded film, characterized in that: include: A core layer having a first surface and a second surface opposite to each other along the film thickness; The high temperature resistant surface layer is double-layered and is disposed on the first surface and the second surface; A high temperature resistant transition layer, sandwiched between the core layer and at least one high temperature resistant surface layer; The intrinsic viscosity of each layer from the core layer to the high temperature resistant surface layer gradually increases.

2. The low precipitation optical film according to claim 1, characterized in that: The core layer comprises at least one recycled material layer stacked in sequence along the layer thickness, and the recycled material layer is connected to the high temperature resistant transition layer or the high temperature resistant surface layer through a compatible layer.

3. The low precipitation optical film according to claim 2, characterized in that: The recycled material of the recycled material layer is one of PET, APET and PETG; the compatible layer is polyester containing polyester-polyether block copolymer or polyester containing polyester-polysiloxane block copolymer.

4. The low precipitation optical film according to claim 1, characterized in that: A surface of at least one of the high temperature resistant surface layers away from the core layer is provided with a high temperature resistant coating.

5. The low precipitation optical film according to claim 4, characterized in that: The high temperature resistant coating is an epoxy modified polyurethane coating.

6. The low precipitation optical film according to claim 1, characterized in that: The thickness ratio of the high temperature resistant surface layer and the core layer is (10-15): (60-80).

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