Colored adhesive film

Abstract

The invention relates to a colored adhesive film, which comprises at least one colored layer, the colored layer comprises a bearing layer and a color layer, the bearing layer has a first VA content, the color layer has a second VA content, the first VA content is gradually increased to the second VA content in gradient distribution, and the first VA content and the second VA content are gradually increased through the gradient between the first VA content and the second VA content. And the flatness of the color layer on the surface of the bearing layer is enhanced. Therefore, the colored adhesive film has the advantages of high light transmittance, good weather resistance, good migration resistance and the like, and the appearance color of the photovoltaic module adopting the colored adhesive film is uniform and full.

Description

Technical Field

[0001] This application relates to the photovoltaic field, and in particular to a colored adhesive film. Background Technology

[0002] Building-integrated photovoltaics (BIPV) is a new concept in solar power generation. Based on the different ways in which the photovoltaic array is integrated with the building, BIPV can be divided into two main categories: one is the combination of the photovoltaic array and the building; the other is the integration of the photovoltaic array and the building. In addition to power generation, BIPV modules also need to be aesthetically pleasing.

[0003] There are several ways to add color to photovoltaic modules, such as coloring the anti-reflective coating on the cells, coloring the photoelectric layer, coloring the encapsulating film, and coloring the front glass. For economic and efficiency reasons, most commercially available colored crystalline silicon photovoltaic products currently achieve the desired color on the front glass through printing coatings, glass coatings, and other methods.

[0004] Photovoltaic modules produced by printing colored enamel onto the surface of tempered glass using screen printing technology have excellent color effects, but the production cost is high, the production cycle is long, the yield is low, and it is not suitable for producing irregularly shaped modules.

[0005] Inorganic pigments are added to the particles and extruded to form a film. The film is brightly colored and can cover the background color of crystalline silicon, but the light transmittance is low, resulting in low power generation efficiency.

[0006] Adding organic pigments to the film produces a film with bright colors and increased light transmittance compared to inorganic pigments. However, organic pigments have relatively poor weather resistance and are prone to migration, resulting in poor appearance of the components.

[0007] Furthermore, the existing manufacturing process for colored films is not yet mature, and it is impossible to simultaneously achieve good color saturation and high power generation efficiency.

[0008] See CN213660431U (hereinafter referred to as Case 431), an invention application filed by Hangzhou FiberNano Optoelectronics Technology Co., Ltd. on December 29, 2022. The first independent claim of this case describes a structure comprising a color layer, an upper interface adhesive layer, and a lower interface adhesive layer, wherein the color layer is disposed between the upper and lower interface adhesive layers, and the materials of the upper and lower interface adhesive layers are respectively polymer film materials...

[0009] In the second independent claim of this case, it can be seen that the colored adhesive film includes a colored layer and an upper interface adhesive layer. The colored layer is disposed below the upper interface adhesive layer. The material of the upper interface adhesive layer is a polymer adhesive film material. The film thickness of the upper interface adhesive layer is 0.45µm~5mm. The film thickness of the colored layer is 200nm~4mm. The upper interface adhesive layer is transparent or semi-transparent.

[0010] After reviewing the scope of each independent claim in Case 431, a closer look was taken at the detailed description in Case 431. It can be seen that the overall description of the colored adhesive film in Case 431 focuses on the configuration of the entire laminated structure. For example, the upper adhesive layer can be an EVA layer or a POE layer, and the lower adhesive layer can also be an EVA layer or a POE layer. Furthermore, the EVA layer or POE layer in both the upper and lower adhesive layers can selectively have a degree of crosslinking.

[0011] Looking at the entire text of Case 431, we can see that there is no definition of the colored layer throughout the entire document. At the same time, the material of the colored layer is not explicitly described or indicated in the detailed description. Therefore, without knowing what the material is, it is reasonable to suspect that there is a high probability of interlayer compatibility issues between the colored layer and the adhesive layer on one side, which may lead to delamination in subsequent processes.

[0012] The overall arrangement of Case 431 does not provide any information about the materials used in the colored layers, nor does it offer any justification for the choice of materials that would allow someone skilled in the art to readily grasp the structure of this application upon reviewing the description in Case 431. Therefore, this application aims to address this issue and proposes solutions to the problem of interlayer compatibility.

[0013] Furthermore, since the subject of the application is to provide a colored adhesive film, and in order to prevent color mixing problems in subsequent processes, the key technical point involved is to pre-crosslink the colored layer to ensure its flatness. Summary of the Invention

[0014] To address the aforementioned problems in the prior art, this application provides a colored adhesive film that has advantages such as good weather resistance, high light transmittance, and migration resistance.

[0015] This application provides a colored adhesive film, comprising at least one colored layer, the colored layer including:

[0016] A bearing layer; and

[0017] A color layer that is tightly bonded to the substrate.

[0018] The carrier layer has a first VA content, and the color layer has a second VA content. The first VA content is distributed in a gradient from the second VA content to the first VA content. The gradient between the first VA content and the second VA content enhances the smoothness of the color layer on the surface of the carrier layer.

[0019] In the colored adhesive film provided in this application, the first VA content is less than 40%, and the second VA content is 70%~90%.

[0020] In the colored adhesive film provided in this application, the thickness of the color layer is 5μm-50μm.

[0021] In the colored adhesive film provided in this application, the light transmittance of the color layer is greater than 80%.

[0022] In the colored adhesive film provided in this application, the pre-crosslinking degree of the color layer is 15%~50%.

[0023] In a colored adhesive film provided in this application, the pre-crosslinking degree of the carrier layer is 20%-70%.

[0024] The colored adhesive film provided in this application further includes at least one first transparent layer, which is tightly adhered to at least one side of the colored layer.

[0025] In a colored adhesive film provided in this application, the colored layer has a first melt flow index, the first transparent layer has a second melt flow index, and the first melt flow index is distributed in an increasing gradient from the second melt flow index.

[0026] In a colored adhesive film provided in this application, the colored layer has a first pre-crosslinking degree, the first transparent layer has a second pre-crosslinking degree, and the first pre-crosslinking degree is distributed in a gradient decreasing from the second pre-crosslinking degree, such that the first melt flow index is less than the second melt flow index.

[0027] The colored adhesive film provided in this application further includes a first transparent layer, which is tightly adhered to one side of the colored layer, and a second transparent layer, which is tightly adhered to the side of the colored layer opposite to the first transparent layer.

[0028] In a colored adhesive film provided in this application, the colored layer has a first melt flow index, the first transparent layer has a second melt flow index, and the second transparent layer has a third melt flow index, and the first melt flow index has an increasing gradient distribution to the second melt flow index, and the second melt flow index has an increasing gradient distribution to the third melt flow index.

[0029] In a colored adhesive film provided in this application, the colored layer has a first pre-crosslinking degree, the first transparent layer has a second pre-crosslinking degree, and the second transparent layer has a third pre-crosslinking degree. The first pre-crosslinking degree is distributed in a decreasing gradient from the second pre-crosslinking degree to the third pre-crosslinking degree, and the second pre-crosslinking degree is distributed in a decreasing gradient from the third pre-crosslinking degree to the first pre-crosslinking degree, such that the first melt flow index is less than the second melt flow index, and the second melt flow index is less than the third melt flow index.

[0030] In the colored adhesive film provided in this application, the first pre-crosslinking degree is 10%-70%. Preferably, the first pre-crosslinking degree is 30%-50%.

[0031] In the colored adhesive film provided in this application, the second pre-crosslinking degree is 9%-50%. Preferably, the second pre-crosslinking degree is 20%-30%.

[0032] In the colored adhesive film provided in this application, the carrier layer, the first transparent layer, and the second transparent layer are independently selected from one of EVA, POE, and PVB. Preferably, the carrier layer is EVA.

[0033] In the colored adhesive film provided in this application, the color layer is preferably VAE.

[0034] In a colored film provided in this application, the color layer is coated with pearlescent pigment.

[0035] In the colored adhesive film provided in this application, the thickness of the colored layer is 0.01mm-0.1mm. Preferably, the thickness of the colored layer is 0.02mm-0.04mm. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of an embodiment of the colored adhesive film of this application.

[0037] Figure 2 This is a schematic diagram of another embodiment of the colored adhesive film of this application.

[0038] Figure 3 This is a schematic diagram of another embodiment of the colored adhesive film of this application.

[0039] Labeling explanation: 10-Color layer; 11-Carrier layer; 12-Color layer; 20-First transparent layer; 30-Second transparent layer. Detailed Implementation

[0040] The following is in conjunction with the appendix Figures 1-3 This application will be described in further detail.

[0041] It should be noted that:

[0042] EVA: Abbreviation for ethylene-vinyl acetate copolymer;

[0043] POE: Abbreviation for ethylene-butene copolymer or ethylene-octene copolymer;

[0044] PVB: Abbreviation for ethylene-vinyl alcohol copolymer butyral;

[0045] VAE: Abbreviation for vinyl acetate-ethylene copolymer.

[0046] VOC: The abbreviation for volatile organic compounds.

[0047] VA content: The content of vinyl acetate in the polymer molecule.

[0048] Pearlescent pigments: a type of optical effect pigment, also known as non-metallic pigments with metallic luster because they exhibit a certain metallic sheen. Pearlescent pigments possess the shimmering effect of metallic pigments while producing the soft luster of natural pearls. When exposed to sunlight, they produce multi-layered reflections, and the interaction of reflected light creates a soft yet dazzling luster and color.

[0049] See Figure 1 As shown, this application provides a colored adhesive film comprising at least one colored layer 10, which includes a carrier layer 11 and a color layer 12 tightly adhered to the carrier layer 11. The carrier layer 11 has a first VA content, and the color layer 12 has a second VA content. The first VA content increases in a gradient distribution towards the second VA content. This gradient enhances the smoothness of the color layer 12 on the surface of the carrier layer 11. The color layer 12 is adhered to the surface of the carrier layer 11 in the form of a coating. The color layer 12 needs to have a certain degree of smoothness to present the best color. Therefore, the compatibility between the color layer 12 and the carrier layer 11 needs to be sufficiently strong, while also meeting stringent environmental protection requirements. Oil-based coatings with high VOC emissions are preferentially excluded. The matrix material used for the color layer 12 is preferably an aqueous VAE emulsion, which helps to disperse pigments evenly. The carrier layer 11 is selected from EVA, POE, and PVB, thus creating an increasing gradient distribution of the first VA content towards the second VA content. VAE exhibits strong compatibility with any of EVA, POE, and PVB. Therefore, the color layer 12 can be smoothly adhered to the surface of the carrier layer 11 as a coating, while ensuring sufficient compatibility between the color layer 12 and the carrier layer 11. This increases the interlayer adhesion between the color layer 12 and the carrier layer 11, preventing delamination and other defects. It should be noted that commercially available EVA, POE, and PVB exist in solid form. Using any of these materials to create a liquid coating would require a large amount of organic solvents, which does not meet the stringent VOC emission requirements.

[0050] Preferably, the first VA content is less than 40%, and the second VA content is 70%~90%.

[0051] Preferably, the color layer 12 is coated with pearlescent pigment. The pearlescent pigment imparts color to the colored film.

[0052] Preferably, the thickness of the color layer 12 is 5μm-50μm. Since pearlescent pigments are in the form of flakes, the thickness of the color layer 12 is set at 5μm-50μm. The main reason for this is that within this thickness range, the pearlescent pigment flakes can be arranged as horizontally as possible, thus allowing the color of the color layer 12 to exhibit the most saturated color. Furthermore, the light transmittance of the color layer 12 can be greater than 80%.

[0053] Preferably, the pre-crosslinking degree of the color layer 12 is 15%~50%, and the pre-crosslinking degree of the carrier layer 11 is 20%-70%. This gives the carrier layer 11 a certain degree of hardness, which can support the color layer 12, ensure the flatness of the color layer 12, and also prevent the flatness of the color layer 12 from being damaged by the melting and flowing of the carrier layer 11 when the colored film is applied to the photovoltaic module.

[0054] Further, see Figure 2 As shown, this application provides a colored adhesive film comprising at least one colored layer 10, which includes a carrier layer 11 and a color layer 12 tightly adhered to the carrier layer, and a first transparent layer 20 tightly adhered to at least one side of the colored layer 12. Preferably, the first transparent layer 20 is tightly adhered to the color layer 12. The colored layer 10 has a first melt flow index, and the first transparent layer 20 has a second melt flow index, with the first melt flow index exhibiting an increasing gradient distribution towards the second melt flow index. Thus, the first transparent layer 20 enhances the adhesion of the colored adhesive film and protects the color layer 12, thereby preventing the color layer 12 from melting and flowing and damaging its smoothness when the colored adhesive film is applied to photovoltaic modules.

[0055] The reason why the first melt flow index shows an increasing gradient distribution from the second melt flow index is that the colored layer 10 has a first pre-crosslinking degree, and the first transparent layer 20 has a second pre-crosslinking degree. The first pre-crosslinking degree shows a decreasing gradient distribution from the second pre-crosslinking degree, so the first melt flow index is smaller than the second melt flow index. The second pre-crosslinking degree is smaller than the first pre-crosslinking degree, which is also the reason why the first transparent layer 20 both enhances the adhesion of the colored adhesive film and protects the colored layer 12. The principle is that the greater the pre-crosslinking degree, the smaller the melt flow index of the resin film, the lower the fluidity, and the worse the adhesion to media such as glass. However, the color layer 12 needs to remain consistent under all circumstances. Therefore, the color layer 12 should not have excessive fluidity. Thus, the color layer 10, which includes the color layer 12 and the carrier layer 11 that carries the color layer 12, needs to be pre-crosslinked. The pre-crosslinking degree of the color layer 10 needs to be greater than that of the first transparent layer 20, that is, the first pre-crosslinking degree is greater than the second pre-crosslinking degree. Only in this way can the flatness of the color layer 12 be guaranteed to remain consistent. It will not cause interlayer interpenetration due to melt flow, forming obvious wrinkles. Instead, it will show a uniform and full appearance.

[0056] Further, see Figure 3 As shown, this application provides a colored adhesive film comprising at least one colored layer 10, which includes a carrier layer 11 and a color layer 12 tightly bonded to the carrier layer. It also includes a first transparent layer 20 tightly bonded to one side of the colored layer and a second transparent layer 30 tightly bonded to the side of the colored layer 10 opposite to the first transparent layer 20. Preferably, the first transparent layer 20 is tightly bonded to the color layer 12, and the second transparent layer 30 is tightly bonded to the carrier layer 11. The colored layer 10 has a first melt flow index, the first transparent layer 20 has a second melt flow index, and the second transparent layer 30 has a third melt flow index, with the first melt flow index exhibiting an increasing gradient distribution from the second melt flow index to the third melt flow index, and vice versa. Thus, the first transparent layer 20 enhances the adhesion of the colored adhesive film and protects the color layer 12, preventing damage to the smoothness of the color layer 12 after melting and flowing when the colored adhesive film is applied to photovoltaic modules. Meanwhile, the second transparent layer 30 compensates for the insufficient adhesion of the carrier layer 11 and further enhances the adhesion of the colored adhesive film.

[0057] The gradient distribution of the first melt flow index increasing towards the second melt flow index, and the gradient distribution of the second melt flow index increasing towards the third melt flow index, is due to the fact that the colored layer 10 has a first pre-crosslinking degree, the first transparent layer 20 has a second pre-crosslinking degree, and the second transparent layer 30 has a third pre-crosslinking degree. Furthermore, the gradient distribution of the first pre-crosslinking degree decreasing towards the second pre-crosslinking degree, and the gradient distribution of the second pre-crosslinking degree decreasing towards the third pre-crosslinking degree, means that the first melt flow index is less than the second melt flow index, and the second melt flow index is less than the third melt flow index. The fundamental principle behind the first melt flow index being less than the second melt flow index is the same as described above and will not be repeated here. The second melt flow index being less than the third melt flow index is because the second transparent layer 30 needs to bond photovoltaic cells. Since the surface roughness of photovoltaic cells is much smaller than that of photovoltaic glass, the photovoltaic encapsulation film needs to have a higher melt flow index to fully wet the surface of the photovoltaic cells and ensure excellent adhesion. Therefore, the second melt flow index is less than the third melt flow index, allowing the second transparent layer 30 to bond the photovoltaic cells more firmly.

[0058] The better the adhesion and aging resistance of the aforementioned colored adhesive film to photovoltaic glass or photovoltaic cells, the better it can ensure that photovoltaic modules using the aforementioned colored adhesive film can generate electricity in a long-term and stable manner. Therefore, without considering the performance of the colored adhesive film, simply stacking the layers cannot guarantee that photovoltaic modules can generate electricity in a long-term and stable manner.

[0059] Furthermore, in the above-mentioned colored adhesive film, the first pre-crosslinking degree is 10%-70%. Preferably, the first pre-crosslinking degree is 30%-50%.

[0060] Furthermore, in the above-mentioned colored adhesive film, the second pre-crosslinking degree is 9%-50%. Preferably, the second pre-crosslinking degree is 20%-30%.

[0061] Furthermore, in the aforementioned colored adhesive film, the first transparent layer 20 and the second transparent layer 30 are independently selected from one of EVA, POE, and PVB. Preferably, the carrier layer is EVA.

[0062] Furthermore, in the aforementioned colored adhesive film, the thickness of the colored layer is 0.01mm-0.1mm. Preferably, the thickness of the colored layer is 0.02mm-0.04mm. Thus, adding the first transparent layer 20 and the second transparent layer 30 can increase the overall thickness of the colored adhesive film, which is necessary to bond the battery surface with the solder ribbon, and to prevent the colored adhesive film from being too thin, causing the solder ribbon to penetrate the colored adhesive film and resulting in defects such as leakage in the photovoltaic module.

[0063] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A colored adhesive film comprising at least one colored layer, characterized in that, The color layer includes: A bearing layer; and A color layer that is tightly bonded to the supporting layer. The carrier layer has a first VA content, and the color layer has a second VA content. The first VA content is distributed in a gradient from the second VA content to the first VA content. The gradient between the first VA content and the second VA content enhances the smoothness of the color layer on the surface of the carrier layer.

2. The colored adhesive film according to claim 1, characterized in that: It also includes at least one first transparent layer, which is tightly adhered to at least one side of the colored layer.

3. The colored adhesive film according to claim 1, characterized in that: It also includes a first transparent layer that is tightly attached to one side of the color layer, and a second transparent layer that is tightly attached to the side of the color layer opposite to the first transparent layer.

4. The colored adhesive film according to claim 2, characterized in that: The colored layer has a first melting index, the first transparent layer has a second melting index, and the first melting index has an increasing gradient distribution towards the second melting index.

5. The colored adhesive film according to claim 4, characterized in that: The colored layer has a first pre-crosslinking degree, and the first transparent layer has a second pre-crosslinking degree. The first pre-crosslinking degree is distributed in a decreasing gradient from the second pre-crosslinking degree, such that the first melt flow index is less than the second melt flow index.

6. The colored adhesive film according to claim 3, characterized in that: The colored layer has a first melting index, the first transparent layer has a second melting index, and the second transparent layer has a third melting index. The first melting index has an increasing gradient distribution towards the second melting index, and the second melting index has an increasing gradient distribution towards the third melting index.

7. The colored adhesive film according to claim 6, characterized in that: The colored layer has a first pre-crosslinking degree, the first transparent layer has a second pre-crosslinking degree, and the second transparent layer has a third pre-crosslinking degree. The first pre-crosslinking degree is distributed in a decreasing gradient from the second pre-crosslinking degree, and the second pre-crosslinking degree is distributed in a decreasing gradient from the third pre-crosslinking degree, such that the first melt flow index is less than the second melt flow index, and the second melt flow index is less than the third melt flow index.

8. The colored adhesive film according to any one of claims 1-7, characterized in that: The first VA content is less than 40%, and the second VA content is 70%~90%; The thickness of the color layer is 5μm-50μm.

9. The colored adhesive film according to claim 8, characterized in that: The light transmittance of the color layer is greater than 80%.

10. The colored adhesive film according to claim 8, characterized in that: The pre-crosslinking degree of the color layer is 15%~50%.

11. The colored adhesive film according to any one of claims 1-7, characterized in that: The pre-crosslinking degree of the carrier layer is 20%-70%.

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