Titanium-free white glass glaze for photovoltaic backboard and preparation method of titanium-free white glass glaze

Abstract

The invention discloses a titanium-free white glass glaze for a photovoltaic backboard and a preparation method of the titanium-free white glass glaze, and belongs to the technical field of glass glazes, the titanium-free white glass glaze for the photovoltaic backboard comprises inorganic powder and an organic carrier; the inorganic powder comprises the following raw materials in percentage by weight: 52-78% of glass powder; 20%-40% of a white pigment composition composed of zinc sulfide and silicon nitride; 2%-8% of a supplement; according to the invention, zinc sulfide and silicon nitride are adopted to completely replace easily reduced titanium dioxide, so that the insulativity and PID resistance of the glaze layer are improved, the photovoltaic backboard glazed glass prepared from the glaze layer has excellent and durable white shading property and reflectivity, and the aging resistance of a component can be greatly improved after the glaze layer is used.

Description

A titanium-free white glass glaze for photovoltaic backsheets and its preparation method Technical Field

[0001] This invention belongs to the field of glass glaze technology, specifically relating to a titanium-free white glass glaze for photovoltaic backsheets and its preparation method. Background Technology

[0002] The white glass enamel used for photovoltaic backsheets has a high reflectivity, which can reflect some of the sunlight that the solar cells cannot absorb at once back onto the cells for secondary use. This can effectively improve the module's efficiency in utilizing light energy and ultimately increase the module's power output, which is crucial for the photovoltaic industry that is pursuing cost reduction and efficiency improvement.

[0003] Currently, mainstream white glazes generally use rutile titanium dioxide as the main white pigment and opacifier. For example, Chinese patent CN11363656A discloses a water-based environmentally friendly white glaze for high-reflectivity anti-PID photovoltaic backsheet glass and its preparation method. The water-based environmentally friendly white glaze includes the following raw material components: 20-25 parts of ink oil, 0.5-1.0 parts of dispersant, 30-45 parts of low melting point glass powder, and 40-50 parts of titanium dioxide.

[0004] However, titanium dioxide has high photocatalytic activity, generating photogenerated electron-hole pairs under ultraviolet light irradiation, which catalyzes the degradation of the encapsulation material, leading to component performance degradation. Furthermore, titanium dioxide is easily reduced, especially under high temperature and humidity environments (particularly under bias conditions). 4+ Easily reduced to Ti³ + This leads to the glaze turning gray and black, reducing electrical insulation and exacerbating the PID effect. After long-term UV aging, glazes using titanium dioxide as a white pigment are prone to yellowing, chalking, and significant reduction in reflectivity. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a titanium-free white glass glaze for photovoltaic backsheets and its preparation method. Zinc sulfide and silicon nitride are used to completely replace easily reduced titanium dioxide, thereby improving the insulation and anti-PID performance of the glaze layer.

[0006] The present invention also provides a photovoltaic backsheet glazed glass, wherein the surface of the photovoltaic backsheet glazed glass is coated with the titanium-free white glass glaze for photovoltaic backsheets described in the present invention, which has excellent and durable white light-blocking properties and reflectivity, and can significantly improve the aging resistance of the module after use.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a titanium-free white glass glaze for photovoltaic backsheets, comprising inorganic powder and an organic carrier; the inorganic powder comprises the following raw materials by weight percentage: 52% to 78% glass powder, 20% to 40% white pigment composition composed of zinc sulfide and silicon nitride, and 2% to 8% supplements.

[0009] The glass powder has a D50 of 3~4μm and a D100 of <10μm.

[0010] The supplement is barium sulfate.

[0011] The weight ratio of zinc sulfide to silicon nitride is 1~3:1.

[0012] The organic carrier comprises the following raw materials by weight percentage: 65%~75% propylene glycol methyl ether, 10%~15% ethylene glycol dimethyl ether, 10%~18% methacrylic acid resin copolymer, 1%~5% leveling agent, 1%~5% dispersant, and 1%~5% wetting agent.

[0013] Furthermore, the grade of the leveling agent is BYK-358N.

[0014] The brand name of the dispersant is Clariant SPS.

[0015] The wetting agent is designated as TEGO 4568.

[0016] The amount of the organic carrier is 35% to 40% of the weight of the inorganic powder.

[0017] The present invention also provides a method for preparing the titanium-free white glass enamel for photovoltaic backsheets, the method comprising the following steps:

[0018] S1. Mix zinc sulfide and silicon nitride, ball mill with water as the medium for 1 to 5 hours, dry and sieve to obtain a white pigment composition;

[0019] S2 mixes and stirs glass powder, white pigment composition, supplements, and organic carrier evenly to obtain titanium-free white glass glaze for photovoltaic backsheets.

[0020] In step S1, the amount of water used is 30% to 50% of the sum of the masses of zinc sulfide and silicon nitride.

[0021] In step S1, the drying temperature is 80℃~150℃; the sieving is done through a 300-mesh sieve.

[0022] The present invention also provides a photovoltaic backsheet glazed glass, wherein the surface of the photovoltaic backsheet glazed glass is coated with the titanium-free white glass glaze for photovoltaic backsheets described in the present invention, the photovoltaic backsheet glazed glass has an adhesion grade of 0 and a reflectivity of more than 78%, and PID288 is completely colorfast, the reflectivity difference after UV120 is ≤1%, and the yellowness value difference is ≤3.

[0023] The present invention also provides a method for preparing the photovoltaic backsheet enamel glass, the method comprising the following steps: printing the photovoltaic backsheet enamel glass of the present invention onto the photovoltaic backsheet glass by screen printing, drying at 100℃~180℃, and tempering in a tempering furnace at 680℃~720℃ for 85s~120s.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1) Fundamentally solve the PID problem: This invention uses zinc sulfide and silicon nitride to completely replace the easily reduced titanium dioxide. Zinc sulfide and silicon nitride have extremely high chemical stability and electrical insulation. They are not prone to oxidation-reduction reaction under PID test conditions, which physically cuts off the current leakage path caused by the reduction of titanium dioxide, thereby greatly improving the insulation and anti-PID performance of the glaze. No discoloration of the glaze appears after PID288.

[0026] 2) Significantly improve the aging resistance of the components: The present invention uses zinc sulfide and silicon nitride to completely replace titanium dioxide with high photocatalytic activity. Zinc sulfide and silicon nitride are chemically inert materials and do not have photocatalytic activity, which fundamentally eliminates a major cause of ultraviolet aging and significantly extends the service life and reliability of photovoltaic modules. After UV120, △R≤1% and △YI≤3.

[0027] 3) Stable reflectivity: Zinc sulfide itself has a high refractive index (~2.37), which works synergistically with silicon nitride (~2.0), barium sulfate (~1.64), and glass powder (refractive index 1.5~1.7) to form a high-medium-low gradient refractive index system, providing excellent and durable white opacity and reflectivity. It can maintain a reflectivity of over 78% under different tempering processes. At the same time, the high whiteness and chemical inertness of barium sulfate can inhibit the slight oxidation of zinc sulfide at high temperatures, ensuring that the glaze does not fade or yellow over long-term use.

[0028] 4) Excellent surface quality and adhesion: This invention uses an organic carrier as a diluent and dispersant for inorganic powders. In the organic carrier, propylene glycol methyl ether and ethylene glycol dimethyl ether serve as a mixed solvent, synergistically regulating the solubility of the organic carrier and matching the surface polarity with glass powder, zinc sulfide, and silicon nitride, reducing van der Waals forces between powders and preventing agglomeration. The dispersant can be adsorbed onto the surface of the inorganic powder through electrostatic repulsion, forming a double-layer structure, further preventing particle agglomeration. The wetting agent can reduce the contact angle between the organic carrier and the inorganic powder, accelerating the wetting of the powder surface by the solvent and ensuring that the powder is completely encapsulated in the carrier. The leveling agent can reduce the surface tension of the organic carrier. Surface tension improves the spreadability of the glaze on the glass surface, ensuring a smooth and even glaze surface free from defects such as orange peel and pinholes after coating. Methacrylic acid resin copolymer, acting as a film-forming agent, forms a continuous and uniform film during screen printing, enhancing the contact between the inorganic powder and the substrate and preventing defects such as sagging and pinholes after coating. It completely decomposes during glass tempering without releasing harmful gases, and the decomposition products are CO2 and H2O, which do not react with the inorganic powder, ensuring no residual impurities in the glaze after tempering. During tempering, the glass powder in the glaze melts and forms Si-O-Si bonds with the SiO2 on the glass surface, achieving a zero-level adhesion between the glaze and glass, making it suitable for use in harsh environments such as high temperature and humidity. Detailed Implementation

[0029] Unless otherwise specified, the experimental methods in the following examples are conventional methods, and the experimental reagents and materials involved are conventional chemical reagents and materials unless otherwise specified.

[0030] The organic carriers used in each embodiment and comparative example are composed of the following raw materials in weight percentage: 70% propylene glycol methyl ether, 12% ethylene glycol dimethyl ether, 14% methacrylic acid resin copolymer, 1.5% BYK-358N leveling agent, 1.5% Clariant SPS dispersant, and 1% TEGO 4568 wetting agent; wherein, the methacrylic acid resin copolymer is a copolymer of methyl methacrylate and butyl acrylate, CAS number 25852-37-3.

[0031] The present invention will now be described in detail with reference to the embodiments.

[0032] Example 1

[0033] A titanium-free white glass glaze for photovoltaic backsheets comprises inorganic powder and an organic carrier; the inorganic powder comprises the following raw materials by weight percentage: 72% glass powder; 20% white pigment composition composed of zinc sulfide and silicon nitride in a weight ratio of 3:1; 8% barium sulfate; the amount of the organic carrier is 35% of the weight of the inorganic powder.

[0034] The preparation method of titanium-free white glass enamel for photovoltaic backsheets includes the following steps:

[0035] S1. Preparation of white pigment composition: Zinc sulfide and silicon nitride are mixed, and water, which accounts for 30% of the sum of their masses, is added as a medium. The mixture is ball-milled for 3 hours, then dried at 80°C, and passed through a 300-mesh sieve to obtain a white pigment composition.

[0036] S2 glaze preparation: Glass powder, white pigment composition, barium sulfate, and organic carrier are mixed and stirred evenly to obtain titanium-free white glass glaze for photovoltaic backsheets.

[0037] Example 2

[0038] A titanium-free white glass glaze for photovoltaic backsheets comprises inorganic powder and an organic carrier; the inorganic powder comprises the following raw materials by weight percentage: 63% glass powder; 32% white pigment composition composed of zinc sulfide and silicon nitride in a weight ratio of 2:1; 5% barium sulfate; the amount of the organic carrier is 37% of the weight of the inorganic powder.

[0039] The preparation method of titanium-free white glass enamel for photovoltaic backsheets includes the following steps:

[0040] S1. Preparation of white pigment composition: Zinc sulfide and silicon nitride are mixed, and water, which accounts for 40% of the sum of their masses, is added as a medium. The mixture is ball-milled for 4 hours, then dried at 120°C, and passed through a 300-mesh sieve to obtain a white pigment composition.

[0041] S2 glaze preparation: Glass powder, white pigment composition, barium sulfate, and organic carrier are mixed and stirred evenly to obtain titanium-free white glass glaze for photovoltaic backsheets.

[0042] Example 3

[0043] A titanium-free white glass glaze for photovoltaic backsheets comprises inorganic powder and an organic carrier; the inorganic powder comprises the following raw materials by weight percentage: 58% glass powder; 40% white pigment composition composed of zinc sulfide and silicon nitride in a weight ratio of 1:1; 2% barium sulfate; the amount of the organic carrier is 40% of the weight of the inorganic powder.

[0044] The preparation method of titanium-free white glass enamel for photovoltaic backsheets includes the following steps:

[0045] S1. Preparation of white pigment composition: Zinc sulfide and silicon nitride are mixed, and water, which accounts for 50% of the sum of their masses, is added as a medium. The mixture is ball-milled for 2 hours, then dried at 150°C and passed through a 300-mesh sieve to obtain a white pigment composition.

[0046] S2 glaze preparation: Glass powder, white pigment composition, barium sulfate, and organic carrier are mixed and stirred evenly to obtain titanium-free white glass glaze for photovoltaic backsheets.

[0047] Comparative Example 1

[0048] The rest is the same as in Example 2, except that the white pigment composition is replaced with an equal mass of rutile titanium dioxide. The preparation method is as follows: glass powder, rutile titanium dioxide, barium sulfate, and organic carrier are mixed and stirred evenly.

[0049] Comparative Example 2

[0050] A titanium-free white glass glaze for photovoltaic backsheets comprises inorganic powder and an organic carrier; the inorganic powder comprises the following raw materials by weight percentage: 72% glass powder; 18% silicon nitride; 10% barium sulfate; the amount of the organic carrier is 35% of the weight of the inorganic powder.

[0051] The preparation method of titanium-free white glass glaze for photovoltaic backsheets includes the following steps: mixing and stirring glass powder, silicon nitride, barium sulfate and organic carrier evenly to obtain titanium-free white glass glaze for photovoltaic backsheets.

[0052] Comparative Example 3

[0053] A titanium-free white glass glaze for photovoltaic backsheets comprises inorganic powder and an organic carrier; the inorganic powder comprises the following raw materials by weight percentage: 58% glass powder; 42% white pigment composition composed of zinc sulfide and silicon nitride in a weight ratio of 1:4; and the organic carrier is used in an amount of 40% of the weight of the inorganic powder.

[0054] The preparation method of titanium-free white glass enamel for photovoltaic backsheets includes the following steps:

[0055] S1. Preparation of white pigment composition: Zinc sulfide and silicon nitride are mixed, and water, which accounts for 50% of the sum of their masses, is added as a medium. The mixture is ball-milled for 5 hours, then dried at 150°C and passed through a 300-mesh sieve to obtain a white pigment composition.

[0056] S2 glaze preparation: Glass powder, white pigment composition and organic carrier are mixed and stirred evenly to obtain titanium-free white glass glaze for photovoltaic backsheets.

[0057] Comparative Example 4

[0058] A titanium-free white glass glaze for photovoltaic backsheets comprises inorganic powder and an organic carrier; the inorganic powder comprises the following raw materials by weight percentage: 72% glass powder; 18% zinc sulfide; 10% barium sulfate; the amount of the organic carrier is 35% of the weight of the inorganic powder.

[0059] The preparation method of titanium-free white glass glaze for photovoltaic backsheets includes the following steps: mixing and stirring glass powder, zinc sulfide, barium sulfate and organic carrier evenly to obtain titanium-free white glass glaze for photovoltaic backsheets.

[0060] The raw materials and amounts of glaze used in each embodiment and comparative example are shown in Table 1.

[0061] Table 1

[0062]

[0063] Test case

[0064] The glazes used in the various embodiments and comparative examples were screen-printed onto the photovoltaic backsheet glass. After drying at 100°C to 180°C, the glass was tempered in a tempering furnace at 680°C to 720°C for 85 to 120 seconds to obtain the final product, glazed photovoltaic backsheet glass.

[0065] Then, the following tests were performed on the photovoltaic backsheet enamel-coated glass prepared in each embodiment and comparative example:

[0066] The reflectance in the visible light band was tested using a colorimeter. Six different locations were tested on each piece of glass, and the average value was taken.

[0067] Adhesion was tested using a cross-cut adhesion tester, referring to GB / T 9286-2021 "Paints and Varnishes - Cross-cut Test".

[0068] After preparing PID samples according to IEC TS 63209-2 "Photovoltaic modules - Extended-stress testing - Part 2: Polymeric component materials", PID tests were conducted at 85%RH, 85℃, and -1500V for 288 hours.

[0069] Referring to JC / T 2170-2013 "Antireflective Film Glass for Solar Photovoltaic Modules", two samples were placed in a UV test chamber for UV 120h testing. The reflectance and yellowness changes of each sample before and after the UV test were measured and the differences were calculated. Six different positions were tested for each piece of glass and the average value was taken.

[0070] The test results of the photovoltaic backsheet enamel-coated glass prepared under different tempering conditions for each embodiment and comparative example are shown in Tables 2 and 3 below:

[0071] Table 2 Performance Testing of Examples and Comparative Examples - 1

[0072]

[0073] Table 3 Performance testing of examples and comparative examples - 2

[0074]

[0075] As can be seen from Tables 2 and 3:

[0076] The photovoltaic backsheet glazed glass prepared from the glazes in each embodiment has an adhesion level of 0 and a reflectivity of over 78% under different tempering processes. Furthermore, it exhibits no discoloration under PID288, and the reflectivity difference after UV120 is ≤1%, while the yellowness difference is ≤3.

[0077] Specifically as follows:

[0078] By mixing zinc sulfide and silicon nitride in different proportions as a white colorant, rutile titanium dioxide can be effectively replaced as a reflectance enhancer in the white glaze of titanium-free glass for white photovoltaic backsheets. At this ratio, both materials combine their respective advantages in adhesion and reflectance, and work synergistically with a small amount of barium sulfate to further improve glaze performance. By adjusting various parameters in glaze preparation, the glaze layer can achieve both Grade 0 adhesion and over 78% reflectance. Furthermore, after 288 hours of PID treatment, there is no discoloration or blackening. After 120 hours of UV treatment, the reflectance and yellowness changes of the glaze surface are within standard ranges, meeting the needs of a wider range of photovoltaic applications.

[0079] The photovoltaic backsheet enamel-coated glass prepared from the enamels in the comparative examples cannot simultaneously meet the requirements for adhesion and reflectivity, as detailed below:

[0080] In Comparative Example 1, the white pigment mixture was replaced with an equal mass of rutile titanium dioxide, based on Example 2. The difference in reflectance was not significant, demonstrating that the reflectance effect of the white pigment composition was not weaker than that of titanium dioxide. However, the photovoltaic backsheet glazed glass prepared in Comparative Example 1 had very poor adhesion, and it turned severely black after PID288. The reflectance and yellowness changes after UV120 also far exceeded the performance standards.

[0081] Comparative Example 2 used silicon nitride as the white pigment and added more barium sulfate as a supplement. Its reflectance decreased sharply compared to Example 1, demonstrating that even with more barium sulfate, reducing the amount of zinc sulfide in the white pigment significantly reduces the reflectance of the glazed glass. Furthermore, the increased amount of barium sulfate resulted in a more pronounced chalking effect in the glaze, leading to a severely excessive change in reflectance after UV120, and the yellowness change also slightly exceeded the standard.

[0082] In Comparative Example 3, barium sulfate was replaced with a white pigment composition in addition to that in Example 3. While the reflectivity improved, the adhesion decreased significantly. Even extending the mixing time of the white pigment composition and increasing the proportion of silicon nitride in the white pigment could not maintain a 0-level adhesion for the glaze. This demonstrates that barium sulfate, as a supplement, needs to be added appropriately to maintain glaze adhesion.

[0083] Comparative Example 4, based on Comparative Example 2, replaced all the white pigment compositions with zinc sulfide, which has a higher reflectivity, and added more barium sulfate as a supplement. However, the reflectivity still could not meet the performance standards, and the adhesion was also significantly reduced.

[0084] The above detailed description of a titanium-free white glass glaze for photovoltaic backsheets and its preparation method is illustrative rather than limiting. Several embodiments can be listed within the defined scope. Therefore, variations and modifications without departing from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A titanium-free white glass enamel for photovoltaic backsheets, characterized in that, The titanium-free white glass glaze for photovoltaic backsheets comprises inorganic powder and organic carrier; the inorganic powder comprises the following raw materials by weight percentage: 52% to 78% glass powder, 20% to 40% white pigment composition composed of zinc sulfide and silicon nitride, and 2% to 8% supplements.

2. The titanium-free white glass enamel for photovoltaic backsheets according to claim 1, characterized in that, The supplement is barium sulfate.

3. The titanium-free white glass enamel for photovoltaic backsheets according to claim 1 or 2, characterized in that, The weight ratio of zinc sulfide to silicon nitride is 1~3:

1.

4. The titanium-free white glass enamel for photovoltaic backsheets according to claim 1 or 2, characterized in that, The organic carrier comprises the following raw materials by weight percentage: 65%~75% propylene glycol methyl ether, 10%~15% ethylene glycol dimethyl ether, 10%~18% methacrylic acid resin copolymer, 1%~5% leveling agent, 1%~5% dispersant, and 1%~5% wetting agent.

5. The titanium-free white glass enamel for photovoltaic backsheets according to claim 1 or 2, characterized in that, The amount of the organic carrier is 35% to 40% of the weight of the inorganic powder.

6. The method for preparing titanium-free white glass enamel for photovoltaic backsheets as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: S1, mixing zinc sulfide and silicon nitride, ball milling with water as the medium for 1h~5h, drying and sieving to obtain a white pigment composition; S2, mixing and stirring glass powder, white pigment composition, supplements and organic carrier evenly to obtain titanium-free white glass glaze for photovoltaic backsheets.

7. The preparation method according to claim 6, characterized in that, In step S1, the amount of water used is 30% to 50% of the sum of the masses of zinc sulfide and silicon nitride.

8. The preparation method according to claim 6, characterized in that, In step S1, the drying temperature is 80℃~150℃; the sieving is done through a 300-mesh sieve.

9. A photovoltaic backsheet enamel-coated glass, characterized in that, The surface of the photovoltaic backsheet enamel glass is coated with the titanium-free white glass enamel for photovoltaic backsheets as described in any one of claims 1-5.

10. The method for preparing photovoltaic backsheet enamel-coated glass as described in claim 9, characterized in that, The preparation method includes the following steps: printing the titanium-free white glass glaze for photovoltaic backsheets as described in any one of claims 1-5 onto the photovoltaic backsheet glass by screen printing, drying at 100℃~180℃, and then tempering it in a tempering furnace at 680℃~720℃ for 85s~120s.

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