Low-shrinkage base film

Abstract

The utility model discloses a low-shrinkage base film, which is a co-extrusion film and comprises a composite core layer, which comprises a PET (polyethylene terephthalate) base layer and a heat-resistant base layer and is provided with a first surface and a second surface opposite to each other along the film thickness direction; the functional layer is arranged on the first surface and / or the second surface; the functional layer is a heat conducting layer and / or a heat reflecting layer; the heat-resistant base layer is a TPU base layer and / or a PI base layer. The low-shrinkage base film is reasonable in structure, the composite core layer containing the heat-resistant base layer is combined with the heat conduction layer and / or the heat reflection layer to serve as the surface layer of the base film, the heat stability of the base film is improved, heat shrinkage of the base film is prevented, and the low-shrinkage effect of the base film is achieved.

Description

Technical Field

[0001] The utility model relates to the field of film technology, in particular to a low-shrinkage base film. Background Art

[0002] Composite films have a wide range of applications in the fields of electronic products, metal products, etc., such as functional protective films, release films, conductive films, etc. During their manufacturing process, they all go through many heating steps and chemical treatment steps. When the base film in the above composite film has poor thermal stability, the base film undergoes thermal shrinkage, resulting in an uneven base film plane and uneven plating or coating on the base film, affecting the optical performance and quality of the composite film. Composite films usually contain polyester films as the base film, which not only have good optical properties but also excellent mechanical properties. However, shrinkage is likely to occur during the preparation of composite films in a high-temperature environment.

[0003] Therefore, it is necessary to improve the base 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-shrinkage base film. By means of a composite core layer containing a heat-resistant base layer, combined with a heat-conducting layer and / or a heat-reflecting layer as the surface layer of the base film, the thermal stability of the base film is improved, its thermal shrinkage is prevented, and the low-shrinkage effect of the base film is achieved.

[0005] To achieve the above technical effects, the technical solution of the utility model is: a low-shrinkage base film, which is a coextruded film and includes:

[0006] A composite core layer, including a PET base layer and a heat-resistant base layer, having a first surface and a second surface opposite to each other in the film thickness direction;

[0007] A functional layer, disposed on the first surface and / or the second surface;

[0008] The functional layer is a heat-conducting layer and / or a heat-reflecting layer;

[0009] The heat-resistant base layer is a TPU base layer and / or a PI base layer.

[0010] The preferred technical solution is that the composite core layer is a laminated structure of TPU / PET / TPU, or PET / TPU / PET, or TPU / PET / PI, or PI / PET / PI, or PET / PI / PET.

[0011] The preferred technical solution is that the heat-conducting layer is one of an aluminum oxide heat-conducting layer, an aluminum nitride heat-conducting layer, and a boron nitride heat-conducting layer.

[0012] The preferred technical solution is that the heat-reflecting layer is one of an aluminum oxide reflecting layer, a titanium dioxide reflecting layer, a zinc oxide reflecting layer, and a tin oxide reflecting layer.

[0013] Preferably, the layer thickness of the TPU base layer in the composite core layer is 10% - 20% of the total layer thickness of the composite core layer.

[0014] Preferably, the layer thickness of the PI base layer in the composite core layer is 5% - 10% of the total layer thickness of the composite core layer.

[0015] Preferably, the total layer thickness of the heat conduction layer and / or the heat reflection layer is 4% - 9% of the total film thickness of the base film, and the total film thickness of the base film is 25 - 150 μm.

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

[0017] The low - shrinkage base film has a reasonable structure. Through the composite core layer containing a heat - resistant base layer, combined with the heat conduction layer and / or the heat reflection layer as the surface layer of the base film, the heat conduction layer guides the temperature on its surface to a uniform state, and the heat reflection layer can reduce the heat transmitted to the surface of the composite core layer. Furthermore, the thermal stability of the base film is improved, preventing its thermal shrinkage and achieving the low - shrinkage effect of the base film. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 2 is a schematic structural diagram of Embodiment 2 of the low - shrinkage base film of the present utility model;

[0020] Figure 3 is a schematic structural diagram of Embodiment 3 of the low - shrinkage base film of the present utility model.

[0021] In the figure: 1. Composite core layer; 2. Functional layer; 11. PET base layer; 12. TPU base layer; 13. PI base layer; 21. Heat reflection layer; 22. Heat conduction layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following combines the drawings and embodiments to further describe the specific implementation manners 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.

[0023] "Surface" is referenced to the normal use state of the low - shrinkage base film. It is only for the convenience of describing the present utility model 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, and thus cannot be understood as a limitation to the present utility model.

[0024] Furthermore, terms such as "first", "second", etc. are for descriptive purposes only and should not 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 creation of the present utility model, unless otherwise stated, the meaning of "a plurality" is two or more.

[0025] Definition

[0026] The PET base layer is a polyethylene terephthalate film;

[0027] The TPU base layer is a thermoplastic polyurethane film;

[0028] The PI base layer is a polyimide film.

[0029] A low-shrinkage base film disclosed by the present utility model is a co-extruded film, including a composite core layer 1 and a functional layer 2. The composite core layer 1 includes a PET base layer 11 and a heat-resistant base layer, and has a first surface (not marked) and a second surface (not marked) that are opposite to each other along the film thickness direction.

[0030] In some embodiments, the functional layer 2 is disposed on the first surface or the second surface, and the functional layer 2 is a heat-conducting layer 22 or a heat-reflecting layer 21.

[0031] In some embodiments, the functional layer 2 is disposed on the first surface and the second surface. Both layers of the functional layer 2 are heat-conducting layers 22; or both layers of the functional layer 2 are heat-reflecting layers 21; or one of the functional layers 2 is a heat-reflecting layer 21 and the other functional layer 2 is a heat-conducting layer 22.

[0032] Furthermore, the heat-conducting layer 22 is one of an aluminum oxide heat-conducting layer, an aluminum nitride heat-conducting layer, and a boron nitride heat-conducting layer. The heat-reflecting layer 21 is one of an aluminum oxide reflecting layer, a titanium dioxide reflecting layer, a zinc oxide reflecting layer, and a tin oxide reflecting layer.

[0033] Titanium dioxide (TiO2) has a high refractive index, can effectively reflect visible light and near-infrared light, and has a relatively low cost; zinc oxide (ZnO) is transparent in the ultraviolet and visible light regions, has good reflectivity in the near-infrared region, and has antibacterial and self-cleaning properties; aluminum oxide (Al2O3) has high thermal stability, can improve the wear resistance and corrosion resistance of materials, and α-Al2O3 has a high refractive index and a dense crystal structure, thereby enhancing infrared reflection; tin oxide (SnO2) can selectively reflect infrared radiation while maintaining visible light transmittance and has good transparency.

[0034] Aluminum oxide (Al2O3) is one of the most common thermal conductive fillers, with a moderate price and good thermal conductivity; boron nitride (BN) has good thermal stability and electrical insulation, and can still maintain its performance at high temperatures; nitrides: aluminum nitride (AlN) has high thermal conductivity and good electrical insulation, and is divided into hexagonal boron nitride (h-BN) and cubic boron nitride (c-BN), among which h-BN has good insulation and high thermal conductivity.

[0035] The heat-resistant base layer is the TPU base layer 12 and / or the PI base layer 13. PET may shrink during heating because the thermal expansion coefficient of PET is relatively high and it will soften at a specific temperature. Composite with TPU and / or PI can improve the thermal stability of PET, thereby reducing shrinkage during the heat treatment process. Especially polyimide (PI), due to its low thermal expansion coefficient and high thermal stability, can significantly improve the dimensional stability and heat resistance of the composite material after being compounded with PET. Compounding TPU with PET can increase the flexibility and impact resistance of PET, while improving its low-temperature resistance and dimensional stability at high temperatures. Further, the composite core layer is a laminated structure of TPU / PET / TPU, or PET / TPU / PET, or TPU / PET / PI, or PI / PET / PI, or PET / PI / PET.

[0036] The layer thickness of the TPU base layer 12 in the composite core layer 1 is 10% - 20% of the total layer thickness of the composite core layer 1.

[0037] The layer thickness of the PI base layer 13 in the composite core layer 1 is 5% - 10% of the total layer thickness of the composite core layer 1.

[0038] The total layer thickness of the thermal conductive layer 22 and / or the thermal reflective layer 21 is 4% - 9% of the total film thickness of the base film, and the total film thickness of the base film is 25 - 150 μm. Since both the thermal conductive layer and the thermal reflective layer have a negative impact on the optical properties of the base film by adding functional particles, therefore, by adjusting the layer thickness of the thermal conductive layer and the thermal reflective layer, the influence of the functional layer on the optical properties of the base film can be optimized, and by selecting and controlling the size of the functional particles, the influence of the functional layer on the optical properties of the base film can be optimized.

[0039] Example 1

[0040] As Figure 1As shown in the figure, the low-shrinkage base film of Example 1 is a co-extruded film, including a composite core layer 1 and a functional layer 2. The composite core layer 1 includes a PET base layer 11 and a heat-resistant base layer, having a first surface and a second surface opposite to each other in the film thickness direction. The functional layer 2 is disposed on the first surface and the second surface. One functional layer 2 is a heat-reflective layer 21, and the other functional layer 2 is a heat-conductive layer 22. Among them, the heat-conductive layer 22 is the inner surface layer, and the heat-reflective layer 21 is the outer surface layer, that is, the surface of the heat-reflective layer 21 is the spraying surface or the plating surface. The composite core layer 1 is a laminated structure of PET / TPU / PET.

[0041] Example 2

[0042] As Figure 2 shown in the figure, Example 2 is based on Example 1, the difference is that the composite core layer 1 is a laminated structure of TPU / PET / TPU, the heat-conductive layer 22 is disposed on the first surface, and the heat-conductive layer 22 is the inner surface layer, and the TPU base layer 12 in the composite core layer 1 is the outer surface layer.

[0043] Example 3

[0044] As Figure 3 shown in the figure, Example 2 is based on Example 1, the difference is that the composite core layer 1 is a laminated structure of TPU / PET / PI, the heat-conductive layer 22 is disposed on the first surface, and the heat-conductive layer 22 is the inner surface layer, and the PI base layer 13 in the composite core layer 1 is the outer surface layer.

[0045] The cost of the base film product of Example 3 is higher than that of the base film products of Example 1 and Example 2, but it can be applied to a higher temperature environment, that is, it has the best high-temperature resistance performance.

[0046] The toughness of the base film product of Example 2 is better than that of the base film product of Example 1.

[0047] The base film product of Example 1 conducts the temperature on its surface to a uniform state through the heat-conductive layer, preventing one surface of the base film from shrinking due to heat. When heated during the coating preparation, due to the setting of the heat-reflective layer, the heat transferred to the surface of the composite core layer is reduced, thereby preventing the other surface of the base film from shrinking due to heat.

[0048] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. A low shrinkage base film, which is a co-extruded film, characterized in that: include: The composite core layer includes a PET base layer and a heat-resistant base layer, and has a first surface and a second surface opposite to each other along a film thickness direction; A functional layer is disposed on the first surface and / or the second surface; The functional layer is a heat conducting layer and / or a heat reflecting layer; The heat-resistant base layer is a TPU base layer and / or a PI base layer.

2. The low shrinkage base film according to claim 1, characterized in that: The composite core layer is a laminated structure of TPU / PET / TPU, or PET / TPU / PET, or TPU / PET / PI, or PI / PET / PI, or PET / PI / PET.

3. The low shrinkage base film according to claim 1 or 2, characterized in that: The heat conducting layer is one of an aluminum oxide heat conducting layer, an aluminum nitride heat conducting layer and a boron nitride heat conducting layer.

4. The low shrinkage base film according to claim 1 or 2, characterized in that: The heat reflection layer is one of an aluminum oxide reflection layer, a titanium dioxide reflection layer, a zinc oxide reflection layer and a tin oxide reflection layer.

5. The low shrinkage base film according to claim 1 or 2, characterized in that: The thickness of the TPU base layer in the composite core layer is 10% to 20% of the total thickness of the composite core layer.

6. The low shrinkage base film according to claim 1 or 2, characterized in that: The thickness of the PI base layer in the composite core layer is 5% to 10% of the total thickness of the composite core layer.

7. The low shrinkage base film according to claim 1, characterized in that: The total thickness of the heat-conducting layer and / or the heat-reflecting layer is 4% to 9% of the total thickness of the base film, and the total thickness of the base film is 25 to 150 μm.

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