Protective film for photovoltaic cell film screen printing plate

Abstract

The invention discloses a protective film for a photovoltaic cell film screen printing plate. The protective film sequentially comprises a first layer, a second layer and a third layer from top to bottom, wherein the first layer is a release film or release paper; the second layer is a TPI (thermoplastic polyimide) adhesive layer, is respectively connected with the first layer and the third layer, and is used for tightly bonding the first layer and the third layer; and the third layer is a PI (polyimide) film. Compared with the prior art, the protective film has the advantages that the PI (polyimide) film is used as a main body structure of the protective film and is matched with the TPI (thermoplastic polyimide) to prepare the composite film through a coating method, and then the composite film is attached to the release film or the release paper to obtain the protective film; the prepared protective film has good heat resistance, reliability, ion migration resistance, weather resistance and flame retardance.

Description

Technical Field

[0001] The invention relates to the technical field of chemical materials, and in particular to a photovoltaic cell film screen protective film and a preparation method thereof. Background Art

[0002] With the rapid development of the photovoltaic semiconductor industry, solar cell screen printing assembly line systems have been widely used at home and abroad. Solar cell screen printing systems are of great significance for improving the photoelectric conversion efficiency of photovoltaic cells, improving production efficiency, and reducing production costs. In this field, some industrial automation powers have always been in a leading position, while some Chinese companies have been in a state of imitation and following. The screen protective films currently produced on the market are mainly epoxy resin covering films and acrylic resin covering films. The thickness of epoxy resin cannot reach the corresponding thickness, and after the thickness of acrylic resin is reduced, the peeling force is low.

[0003] In view of this, based on the in-depth study of the screen printing process and the in-depth analysis of the factors affecting the quality of screen printing, it is necessary to draw on the advantageous technologies and experience in screen printing systems at home and abroad to design and develop a set of solar cell screen printing screen protective film. Summary of the invention

[0004] The purpose of the present invention is to provide a photovoltaic cell film screen protective film and a preparation method thereof, so as to solve the technical problem that the thickness of epoxy resin cannot reach the corresponding thickness and the peeling force is low after the thickness of acrylic resin is reduced.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A photovoltaic cell film screen protective film, the protective film comprises from top to bottom:

[0007] The first layer is a release film or release paper, which is used to protect the non-adhesiveness of the film during processing, storage and transportation;

[0008] The second layer is a TPI (thermoplastic polyimide) adhesive layer, which is connected to the first layer and the third layer respectively, and is used to tightly bond the first layer to the third layer and ensure the flexibility and durability of the entire protective film;

[0009] The third layer is the PI (polyimide) film, which serves as the main structure of the protective film and is used to protect the photovoltaic cell film screen from damage by the external environment.

[0010] Further, the thickness of the PI film ranges from 2 μm to 12.5 μm.

[0011] Furthermore, the thickness of the TPI adhesive layer ranges from 2 μm to 10 μm.

[0012] Furthermore, the thickness of the release film ranges from 20 μm to 100 μm; and the weight of the release paper ranges from 50 g to 150 g.

[0013] Furthermore, the protective film further comprises one or more additives.

[0014] Furthermore, a method for preparing a photovoltaic cell film screen protective film includes the following steps: coating a TPI adhesive solution on a PI film, controlling the dry adhesive thickness to be 2 μm to 10 μm, drying and partially cross-linking, and curing in an oven at 80°C for 3 hours to obtain a composite film, and then laminating the composite film with a release film or release paper to obtain a protective film.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] PI (polyimide) film is used as the main structure of the protective film, and TPI (thermoplastic polyimide) is combined with the coating method to obtain a composite film, and then the composite film is laminated with a release film or release paper to obtain a protective film. The prepared protective film has good heat resistance and reliability, ion migration resistance, weather resistance and flame retardancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the result of dynamic thermomechanical analysis of adhesive and PI composite film.

[0018] Figure 2 Comb circuit used for ion migration resistance test.

[0019] Figure 3 This is the test result of the protective film's resistance to ion migration.

[0020] Figure 4 This is the test result of the protective film peeling strength.

[0021] Figure 5 This is the flame retardant performance test result of the protective film. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] A photovoltaic cell film screen protective film, the protective film comprises from top to bottom: a first layer, which is a release film or release paper, used for the non-adhesion property of the protective film during processing, storage and transportation; a second layer, which is a TPI (thermoplastic polyimide) adhesive layer, which is respectively connected to the first layer and the third layer, and is used for tightly bonding the first layer and the third layer and ensuring the flexibility and durability of the entire protective film; the third layer, which is a PI (polyimide) film, serves as the main structure of the protective film and is used for protecting the photovoltaic cell film screen from damage by the external environment.

[0025] In this embodiment 1, TPI and PI provide excellent bonding performance, temperature resistance, high strength and light transmittance as well as overall flexibility and durability, thereby ensuring the safety and reliability of the photovoltaic cell film screen during production, storage, transportation and use.

[0026] Example 2

[0027] A photovoltaic cell film screen protective film, the protective film comprises from top to bottom: a first layer, which is a release film or release paper, used for the non-adhesion property of the protective film during processing, storage and transportation; a second layer, which is a TPI (thermoplastic polyimide) adhesive layer, which is respectively connected to the first layer and the third layer, and is used for tightly bonding the first layer and the third layer and ensuring the flexibility and durability of the entire protective film; the third layer, which is a PI (polyimide) film, serves as the main structure of the protective film and is used for protecting the photovoltaic cell film screen from damage by the external environment.

[0028] The thickness of the PI film ranges from 2 μm to 12.5 μm.

[0029] Based on Example 1, this Example 2 provides a more preferred thickness range of 2 μm to 12.5 μm for the PI film to meet the protection requirements for the photovoltaic cell film screen while maintaining good light transmittance and mechanical strength.

[0030] Example 3

[0031] A photovoltaic cell film screen protective film, the protective film comprises from top to bottom: a first layer, which is a release film or release paper, used for the non-adhesion property of the protective film during processing, storage and transportation; a second layer, which is a TPI (thermoplastic polyimide) adhesive layer, which is respectively connected to the first layer and the third layer, and is used for tightly bonding the first layer and the third layer and ensuring the flexibility and durability of the entire protective film; the third layer, which is a PI (polyimide) film, serves as the main structure of the protective film and is used for protecting the photovoltaic cell film screen from damage by the external environment.

[0032] The thickness of the TPI glue layer ranges from 2μm to 10μm.

[0033] Based on Example 1, Example 3 provides a more preferred thickness range of 2 μm to 10 μm for the TPI adhesive layer to ensure good bonding effect and suitable flexibility.

[0034] Example 4

[0035] A photovoltaic cell film screen protective film, the protective film comprises from top to bottom: a first layer, which is a release film or release paper, used for the non-adhesion property of the protective film during processing, storage and transportation; a second layer, which is a TPI (thermoplastic polyimide) adhesive layer, which is respectively connected to the first layer and the third layer, and is used for tightly bonding the first layer and the third layer and ensuring the flexibility and durability of the entire protective film; the third layer, which is a PI (polyimide) film, serves as the main structure of the protective film and is used for protecting the photovoltaic cell film screen from damage by the external environment.

[0036] The thickness of the release film ranges from 20 μm to 100 μm; the weight of the release paper ranges from 50 g to 150 g.

[0037] Based on Example 1, Example 4 provides a more preferred thickness range of 20 μm to 100 μm for the release film and a more preferred weight range of 50 g to 150 g for the release paper, so as to provide sufficient mechanical support while ensuring easy peeling.

[0038] Example 5

[0039] A photovoltaic cell film screen protective film, the protective film comprises from top to bottom: a first layer, which is a release film or release paper, used for the non-adhesion property of the protective film during processing, storage and transportation; a second layer, which is a TPI (thermoplastic polyimide) adhesive layer, which is respectively connected to the first layer and the third layer, and is used for tightly bonding the first layer and the third layer and ensuring the flexibility and durability of the entire protective film; the third layer, which is a PI (polyimide) film, serves as the main structure of the protective film and is used for protecting the photovoltaic cell film screen from damage by the external environment.

[0040] The protective film may further include one or more additives.

[0041] This embodiment 5 provides a more preferred structure based on embodiment 1, by adding flame retardants, toughening agents, etc. to improve its heat resistance, chemical resistance, and optical properties.

[0042] Example 6

[0043] A photovoltaic cell film screen protective film, the protective film comprises from top to bottom: a first layer, which is a release film or release paper, used for the non-adhesion property of the protective film during processing, storage and transportation; a second layer, which is a TPI (thermoplastic polyimide) adhesive layer, which is respectively connected to the first layer and the third layer, and is used for tightly bonding the first layer and the third layer and ensuring the flexibility and durability of the entire protective film; the third layer, which is a PI (polyimide) film, serves as the main structure of the protective film and is used for protecting the photovoltaic cell film screen from damage by the external environment.

[0044] The TPI adhesive solution is coated on the PI film, and the dry adhesive thickness is controlled to be 2μm to 10μm. After drying and partial cross-linking, it is placed in an oven at 80°C for curing for 3 hours to obtain a composite film. The composite film is then laminated to a release film or release paper to obtain a protective film.

[0045] This Example 6 provides a more preferred method for preparing the protective film based on Example 1. The protective film prepared by combining the polyimide resin with this method has good performance.

[0046] Test Case

[0047] The performance of the protective film prepared in Example 6 was tested, and the results are as follows: Figure 1-5 The glass transition temperature of the protective film was tested by dynamic thermal mechanical analysis (DMA), and the test curve is shown in Figure 1 As shown by Figure 1 It can be seen that the peak values ​​of the dielectric loss factor (tanδ) correspond to temperatures of 180°C and 333°C, which are the glass transition temperatures of the PAID protective film and the copper foil or copper plate, respectively. The glass transition temperature of the PAID adhesive is much higher than that of the epoxy resin adhesive and the acrylate adhesive used for the epoxy substrate (<100°C). This shows that the heat resistance and reliability of the protective film of the present invention are better than those of the epoxy resin adhesive and the acrylate adhesive. Figure 3 It can be seen that the protective film of the present invention has very high insulation reliability.

[0048] Depend on Figure 4 It can be seen that before treatment, the peel strength of a photovoltaic cell film screen protective film was 1.28kgf / cm. After 240h treatment, the peel strength decreased, but still remained at a high level (1.06kgf / cm), meeting the use requirements of a photovoltaic cell film screen protective film. The weather resistance test results show that the adhesive with polyimide as the main resin has good resistance to moisture and heat aging and can be used for the preparation of a photovoltaic cell film screen protective film. Figure 5This is the flame retardant test result of the protective film. During the test, the flame extinguishing time was less than 1s, which means that the flame retardant grade of the protective film reached UL94-V-0. The excellent flame retardant performance of the protective film is closely related to the PAID resin (limiting oxygen index is 47%). The addition of reactive phosphorus flame retardants (DOPO, SPH-100) in the adhesive can further improve the flame retardant performance of the protective film.

[0049] Table 1 is a comprehensive performance test table of the protective film. It can be seen from Table 1 that various properties of the protective film of the present invention meet the IPC standard.

[0050]

[0051] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or modifications made to the main design concept and spirit of the present invention that have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A photovoltaic cell film screen protective film, characterized in that: The protective film includes from top to bottom: The first layer is a release film or release paper, which is used to protect the non-adhesiveness of the film during processing, storage and transportation; The second layer is a TPI (thermoplastic polyimide) adhesive layer, which is connected to the first layer and the third layer respectively, and is used to tightly bond the first layer to the third layer and ensure the flexibility and durability of the entire protective film; The third layer is the PI (polyimide) film, which serves as the main structure of the protective film and is used to protect the photovoltaic cell film screen from damage by the external environment.

2. A photovoltaic cell film screen protective film according to claim 1, characterized in that: The thickness of the PI film ranges from 2 μm to 12.5 μm.

3. The photovoltaic cell film screen protective film according to claim 1, characterized in that: The thickness of the TPI glue layer ranges from 2μm to 10μm.

4. The photovoltaic cell film screen protective film according to claim 1, characterized in that: The thickness of the release film ranges from 20 μm to 100 μm; the weight of the release paper ranges from 50 g to 150 g.

5. The photovoltaic cell film screen protective film according to claim 1, characterized in that: The protective film may further include one or more additives.

6. A method for preparing a photovoltaic cell film screen protective film according to any one of claims 1 to 5, characterized in that: The following steps are involved: The TPI adhesive solution is coated on the PI film, and the dry adhesive thickness is controlled to be 2μm to 10μm. After drying and partial cross-linking, it is placed in an oven at 80°C for curing for 3 hours to obtain a composite film. The composite film is then laminated to a release film or release paper to obtain a protective film.

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