Release film for phase change sheet
By introducing a barrier layer structure of EVOH layer and metallocene polyethylene layer into the release film for phase change sheets, the problem of aging of PET substrate release film under extreme conditions is solved, achieving better protection and durability.
Patent Information
- Application Number
- CN202423269196.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2034-12-30
AI Technical Summary
Existing PET-based release films are prone to aging under extreme conditions, leading to the failure of phase change thermal conductive materials and insufficient weather resistance.
The barrier layer, which consists of a laminate of EVOH layer and metallocene polyethylene layer, is combined with a substrate layer made of polyethylene terephthalate to enhance the barrier and mechanical properties of the release film.
It improves the barrier properties, mechanical properties and durability of the release film, protects the phase change sheet from environmental impacts during transportation and storage, and extends its service life.
Smart Images
Figure CN223890595U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of release film technology, and in particular to a release film for phase change sheets. Background Technology
[0002] The primary purpose of covering the surface of phase change sheets (such as phase change thermal conductive materials used for heat dissipation) with release films is to prevent contamination, scratches, or other physical damage during transportation, storage, and installation. It may also be necessary to protect the material from environmental factors. Release films should possess good weather resistance, maintaining stable physical properties and adhesion even after prolonged storage under varying temperature and humidity conditions, without producing bubbles or edge lifting. While existing PET-based release films offer good weather resistance, long-term exposure to extreme conditions can still lead to performance degradation or aging, resulting in a failure to protect the phase change thermal conductive material.
[0003] Therefore, it is necessary to improve the release film used in existing phase change sheets. Utility Model Content
[0004] The purpose of this invention is to overcome the defects in the existing technology and provide a release film for phase change sheets. The release film is composed of a barrier layer made of EVOH layer and metallocene polyethylene layer, and is combined with a substrate layer made of polyethylene terephthalate, thereby improving the barrier performance, mechanical properties and durability of the release film.
[0005] To achieve the above-mentioned technical effects, the technical solution of this utility model is: a release film for phase change sheets, comprising:
[0006] The substrate layer has a first surface and a second surface opposite each other along the layer thickness, and is made of polyethylene terephthalate.
[0007] A barrier layer, disposed on the first surface and / or the second surface, includes at least one EVOH layer and a metallocene polyethylene layer;
[0008] A connecting layer is sandwiched between the barrier layer and the substrate layer;
[0009] A release layer is the surface layer of a release film, disposed on the surface of the substrate layer away from the barrier layer, or on the surface of the barrier layer away from the substrate layer.
[0010] A preferred technical solution is that the barrier layer is a laminated structure of linear low-density polyethylene layer / EVOH layer / metallocene polyethylene layer, or metallocene polyethylene layer / EVOH layer / metallocene polyethylene layer, or linear low-density polyethylene layer / EVOH layer / EVOH layer / linear low-density polyethylene layer / metallocene polyethylene layer.
[0011] A preferred technical solution is that the metallocene polyethylene layer is disposed on a surface away from the substrate layer.
[0012] A preferred technical solution is that the EVOH layer and the metallocene polyethylene layer, and the EVOH layer and the linear low-density polyethylene layer are connected by an adhesive layer, wherein the adhesive layer is a maleic anhydride-grafted linear low-density polyethylene layer.
[0013] A preferred technical solution is that the connecting layer is a hot melt adhesive layer.
[0014] A preferred technical solution is that the substrate layer and / or barrier layer contains an anti-ultraviolet unit layer.
[0015] The preferred technical solution is that the release layer is a silicone oil release layer.
[0016] The preferred technical solution is that the thickness of the substrate layer is 50~100μm, the thickness of the connecting layer is 8~12μm, the thickness of the barrier layer is 35~50μm, and the thickness of the release layer is 1~3μm.
[0017] The advantages and beneficial effects of this utility model are as follows:
[0018] The phase change sheet uses a reasonable release film structure, which consists of a barrier layer made of stacked EVOH layer and metallocene polyethylene layer, and is combined with a polyethylene terephthalate substrate layer to improve the barrier performance, mechanical properties and durability of the release film. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the release film structure for phase change sheets of this utility model;
[0020] Figure 2 This is a schematic diagram of the release film structure two for phase change sheets of this utility model.
[0021] In the figure: 1. Substrate layer; 2. Barrier layer; 3. Connecting layer; 4. Release layer; 20. Adhesive layer; 21. EVOH layer; 22. Metallocene polyethylene layer; 23. Linear low-density polyethylene layer. Detailed Implementation
[0022] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.
[0023] The terms "surface" and "surface layer" are used with reference to the normal operating state of the release film for phase change sheets. They are used only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.
[0024] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.
[0025] like Figures 1-2 As shown, the release film for phase change sheets of this utility model includes a substrate layer 1, a barrier layer 2, a connecting layer 3, and a release layer 4. The substrate layer 1 has a first surface (not marked) and a second surface (not marked) opposite each other along the layer thickness, and is made of polyethylene terephthalate. The barrier layer 2 includes at least one EVOH layer 21 and a metallocene polyethylene layer 22. The barrier layer 2 is a single layer or a double layer. The barrier layer 2 is connected to the substrate layer 1 through the connecting layer 3. The release layer 4 is the surface layer of the release film. When the barrier layer 2 is a single layer, the release layer 4 and the barrier layer 2 are respectively disposed on the two surfaces of the substrate layer 1. When the barrier layer 2 is a double layer, the release layer 4 is disposed on the surface of one of the barrier layers 2 away from the substrate layer 1.
[0026] The barrier layer 2, which is formed by stacking EVOH layer 21 and metallocene polyethylene layer 22, and then composited with a substrate layer 1 made of polyethylene terephthalate, improves the barrier performance, mechanical properties and durability of the release film.
[0027] Barrier layer stack structure 1: linear low-density polyethylene layer / EVOH layer / metallocene polyethylene layer;
[0028] Barrier layer stacked structure 2: metallocene polyethylene layer / EVOH layer / metallocene polyethylene layer;
[0029] Barrier layer stack structure three: linear low-density polyethylene layer / EVOH layer / EVOH layer / linear low-density polyethylene layer / metallocene polyethylene layer.
[0030] EVOH has excellent gas barrier properties, with extremely high barrier effects against oxygen, carbon dioxide and water vapor; it also has good transparency, revealing the state of the internal phase change sheet.
[0031] The metallocene polyethylene layer 22 is positioned on a surface away from the substrate layer. It has a relatively low surface energy, meaning it is less prone to adhering to contaminants such as dust and oil. The low surface energy also makes it more difficult for liquids and other particles to adhere to its surface, thus reducing the likelihood of contamination. Its uniform molecular weight distribution and high crystallinity result in a very smooth and flat surface. This smooth surface reduces the chance of contaminants embedding or remaining, making cleaning easier. The stable molecular structure prevents degradation or deterioration under long-term exposure to ultraviolet light, oxygen, and other environmental factors, thus maintaining its surface properties and anti-fouling effect for an extended period. It also enhances barrier properties, effectively protecting EVOH from moisture as an outer layer material, further improving the overall barrier effect, especially in humid environments. The high puncture and tear resistance provided by the metallocene polyethylene layer makes the composite material more robust and durable, particularly suitable for protecting products that may encounter harsh conditions during transportation and storage.
[0032] Linear low-density polyethylene (LLDPE) further improves the barrier properties, puncture resistance, and tear strength of release films, and also optimizes the toughness of release films. Without affecting key performance, it reduces the amount of EVOH and metallocene polyethylene used, thereby reducing material costs and improving economic efficiency.
[0033] The EVOH layer 21 and the metallocene polyethylene layer 22, and the EVOH layer 21 and the linear low-density polyethylene layer 23 are connected by an adhesive layer 20, which is a maleic anhydride-grafted linear low-density polyethylene layer.
[0034] The connecting layer 3 is a hot melt adhesive layer. Hot melt adhesive is liquid when heated, and rapidly cools and solidifies after application, forming a strong adhesive layer. This shortens processing time, improves production efficiency, and is particularly suitable for high-speed operations on continuous production lines. Hot melt adhesive is in solid form and does not require solvent dissolution during use; it is applied entirely by heating, avoiding the environmental pollution and health risks that solvent-based adhesives may pose, making it more environmentally friendly and safer. Hot melt adhesive maintains good bonding performance over a wide temperature range, and some special hot melt adhesives can even withstand high-temperature environments. Hot melt adhesive typically possesses a certain degree of flexibility and elasticity, allowing it to adapt to minor deformations between substrates without easily breaking. This enhances the overall durability of the composite material, especially in applications under dynamic stress.
[0035] To improve the durability of the release film, the substrate layer 1 and / or the barrier layer 2 contain UV-resistant unit layers. In the laminated structure of the barrier layer 3, the metallocene polyethylene layer 22 is a UV-resistant unit layer. The substrate layer 1 is formed by co-extrusion of a surface layer, a core layer, and a surface layer, wherein the surface layer may be a UV-resistant unit layer.
[0036] Release layer 4 is a silicone oil release layer, which can remain stable over a wide temperature range.
[0037] The thickness of the substrate layer 1 is 50~100μm, the thickness of the connecting layer 3 is 8~12μm, the thickness of the barrier layer 2 is 35~50μm, and the thickness of the release layer 4 is 1~3μm.
[0038] like Figure 1 As shown, the release film structure one consists of a release layer / substrate layer / connecting layer / barrier layer, with the barrier layer being a stacked structure of barrier layers.
[0039] like Figure 2 As shown, release film structure two consists of a release layer / substrate layer / connector layer / barrier layer, with the barrier layer being a stacked structure three. This structure offers superior barrier performance and mechanical properties compared to structure one.
[0040] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.
Claims
1. A release film for phase change sheets, characterized in that, include: The substrate layer has a first surface and a second surface opposite each other along the layer thickness, and is made of polyethylene terephthalate. A barrier layer, disposed on the first surface and / or the second surface, includes at least one EVOH layer and a metallocene polyethylene layer; A connecting layer is sandwiched between the barrier layer and the substrate layer; A release layer is the surface layer of a release film, disposed on the surface of the substrate layer away from the barrier layer, or on the surface of the barrier layer away from the substrate layer.
2. The release film for phase change sheets according to claim 1, characterized in that, The barrier layer is a stacked structure of linear low-density polyethylene layer / EVOH layer / metallocene polyethylene layer, or metallocene polyethylene layer / EVOH layer / metallocene polyethylene layer, or linear low-density polyethylene layer / EVOH layer / EVOH layer / linear low-density polyethylene layer / metallocene polyethylene layer.
3. The release film for phase change sheets according to claim 2, characterized in that, The metallocene polyethylene layer is disposed on a surface away from the substrate layer.
4. The release film for phase change sheets according to claim 3, characterized in that, The EVOH layer and the metallocene polyethylene layer, and the EVOH layer and the linear low-density polyethylene layer are connected by an adhesive layer, which is a maleic anhydride-grafted linear low-density polyethylene layer.
5. The release film for phase change sheets according to claim 1, characterized in that, The connecting layer is a hot melt adhesive layer.
6. The release film for phase change sheets according to claim 1, characterized in that, The substrate layer and / or barrier layer contain an anti-ultraviolet unit layer.
7. The release film for phase change sheets according to claim 1, characterized in that, The release layer is a silicone oil release layer.
8. The release film for phase change sheets according to claim 1, characterized in that, The substrate layer has a thickness of 50~100μm, the connecting layer has a thickness of 8~12μm, the barrier layer has a thickness of 35~50μm, and the release layer has a thickness of 1~3μm.