High-strength low-melting-point glass binder and application thereof in photovoltaic glass

Abstract

The invention discloses a high-strength low-melting-point glass binder and application thereof in photovoltaic glass. According to the binder, Bi2O3-B2O3-ZnO is used as a main body system, and SiO2, Al2O3, CeO2, ZrO2 and other components are introduced, so that the glass network stability and the interface bonding strength are remarkably improved while the low softening temperature is kept. When being used for a reflective coating of photovoltaic backboard glass, the coating can form a compact coating under a low-temperature sintering condition, and has excellent damp-heat durability and optical stability.

Description

Technical Field

[0001] This invention relates to the technical field of glass adhesives, and in particular to a high-strength, low-melting-point glass adhesive and its application in photovoltaic glass. Background Technology

[0002] With the rapid development of the photovoltaic industry, the importance of backsheet glass in module structure is becoming increasingly prominent. To improve the module's light utilization efficiency, enhance back reflectivity, and improve overall weather resistance, a glass slurry composed of inorganic glass powder, organic carrier, and functional additives is typically applied to the surface of the backsheet glass, followed by sintering and curing to form a reflective coating. In this process, low-melting-point glass powder acts as a binder, playing a crucial role in coating densification, pigment fixation, and interfacial bonding with the glass substrate. In recent years, to reduce sintering temperatures and ensure compatibility with photovoltaic glass heat treatment processes, the industry has widely adopted low-melting-point glass systems based on Bi2O3-B2O3-ZnO, which offer advantages such as lower glass transition temperatures, good fluidity, and the ability to achieve surface melting and film formation at lower temperatures. However, as photovoltaic modules develop towards long-term outdoor use, high power density, and high reliability, the backsheet glass coating needs to withstand complex conditions such as long-term high temperature, high humidity, ultraviolet radiation, and cold / heat cycling. The shortcomings of traditional low-melting-point glass systems in terms of chemical stability, interfacial bonding ability, and damp heat durability are gradually becoming apparent, making it difficult to meet the requirements of long-term stable operation of the new generation of photovoltaic modules.

[0003] In existing technologies, low-melting-point glass powders, due to their high proportion of non-bridging oxygen in their network structure and loose glass skeleton, are prone to water molecule and hydroxyl infiltration and hydrolysis reactions under humid and hot conditions, disrupting the limited chemical bonds already established between the low-melting-point glass and the backsheet glass. Furthermore, the low melting temperature and rapid viscosity change of low-melting-point glass result in limited wettability with high-silicon photovoltaic glass during sintering, making it difficult to form a sufficient number of stable Si-OM (M being Bi, Zn, etc.) bridging structures in the resulting interface layer. This makes them more susceptible to interface hydration, structural relaxation, and microcrack initiation in humid and hot environments. The combined effect of these factors gradually weakens the adhesion between the reflective coating and the glass substrate in long-term humid and hot environments, especially under harsh aging conditions of 85℃ / 85%RH. Microscopic peeling layers easily form at the interface and extend outwards, ultimately leading to sheet-like coating detachment or large-area failure, severely impacting the reflection efficiency and reliability of photovoltaic modules. Existing technologies, limited by the inherent structural characteristics of low-melting-point glass systems, generally cannot achieve a balance between low melting point, good fluidity, and high humid and hot stability. Therefore, there is an urgent need to develop a high-strength, low-melting-point glass adhesive that can form a high-strength, stable interface under low-temperature sintering conditions, while possessing excellent damp heat durability and chemical stability, so as to significantly improve the durability and adhesion reliability of photovoltaic backsheet glass reflective coatings under long-term high temperature and high humidity environments. Summary of the Invention

[0004] This application provides a high-strength, low-melting-point glass adhesive, comprising the following components by weight: 40-60 parts Bi2O3, 10-20 parts B2O3, 5-15 parts ZnO, 5-10 parts SiO2, 3-8 parts Al2O3, 1-5 parts CeO2, 1-4 parts ZrO2, and 0.5-2 parts CaF2; the high-strength, low-melting-point glass adhesive has a glass transition temperature of 350-450℃ and a softening temperature of 400-500℃.

[0005] It should be noted that the high-strength, low-melting-point glass binder described in this application uses Bi2O3-B2O3-ZnO as its core system. Bi2O3, as the main network exogenous body, provides excellent low-melting-point properties and good flowability. B2O3, as the network forming body, further reduces viscosity and promotes melting. ZnO, as an intermediate oxide, enhances chemical stability and mechanical strength. The introduction of SiO2 and Al2O3 strengthens the glass skeleton's density and hydrolysis resistance, reduces the proportion of non-bridging oxygen, and inhibits hydrolysis reactions caused by water molecule infiltration under humid and hot conditions. The key lies in the appropriate addition of CeO2 and ZrO2 as network modifiers. CeO2, through Ce… 3+ / Ce 4+ The variable valence inhibits oxygen ion migration and promotes the conversion of [BO3] to [BO4], increasing the degree of network crosslinking. ZrO2 strengthens the structural compactness with [ZrO6] or [ZrO4] units, and reacts with the high-silicon network of the photovoltaic glass matrix during low-temperature sintering to form a large number of stable multi-element metal oxides, significantly improving interfacial bonding strength and hydrolysis resistance. CaF2 acts as a flux to further optimize fluidity and lower melting temperature. The synergistic effect of these components achieves a balance between low melting point and high strength. While maintaining excellent sintering fluidity, it significantly improves the chemical stability and damp heat durability of the glass, solving the problems of interfacial hydration, structural relaxation, and delamination that are common in traditional Bi-based low-melting-point glasses. This makes it particularly suitable for long-term reliable application of photovoltaic backsheet glass reflective coatings in high-temperature and high-humidity environments.

[0006] As a preferred technical solution for a high-strength, low-melting-point glass adhesive, it further includes 0.5-3 parts TiO2 and / or 0.5-2 parts MgO by weight.

[0007] It should be noted that, in the high-strength, low-melting-point glass binder described in this application, 0.5-3 parts by weight of TiO2 and / or 0.5-2 parts by weight may be added to further optimize the overall performance of the glass. TiO2, as an intermediate oxide, can exhibit a [TiO4] or [TiO6] coordination structure in the glass network. On the one hand, it improves the chemical durability and hydrolysis resistance of the glass, reduces the exposure of non-bridging oxygen under humid and hot conditions, and inhibits water molecule penetration; on the other hand, it enhances optical stability and UV resistance, reduces reflectivity decay caused by long-term outdoor exposure, and improves the refractive index of the glass and its compatibility with TiO2 pigments, promoting high reflectivity and uniformity of the coating during sintering. MgO, as a network modifier, can further strengthen the cross-linking degree of the glass skeleton, reduce the coefficient of thermal expansion, improve the thermal compatibility with the photovoltaic glass substrate, and enhance the overall mechanical strength and thermal stability. This optional addition, without significantly affecting the low melting point and fluidity, works synergistically with CeO2 and ZrO2 to improve the glass's anti-aging ability and interface durability, enabling the reflective coating to exhibit superior long-term reliability in complex outdoor environments, making it particularly suitable for backsheet applications of high power density photovoltaic modules.

[0008] In addition, this application provides a method for preparing a high-strength, low-melting-point glass adhesive, comprising the following steps:

[0009] Step S1. Raw material preparation: Weigh each component raw material according to the weight parts, dry them at 120℃ for 2-4 hours to remove moisture, and mix all raw materials evenly in the preliminary stage;

[0010] Step S2. Melting process: Place the mixed raw materials in a platinum crucible, and in an air atmosphere, first heat to 800-1000℃ at 5-10℃ / min, hold for 30-60 minutes to remove air bubbles, then heat to 1200-1400℃, hold for 2-4 hours, and stir intermittently to form a uniform glass melt.

[0011] Step S3. Water quenching into blocks: Pour the molten glass into deionized water at 10-20℃ for water quenching to form glass fragments. After drying, check that the glass is transparent or translucent and free of bubbles.

[0012] Step S4. Vacuum annealing treatment - ball milling: Place the dried glass fragments in a vacuum furnace (vacuum degree ≤ 10). -3 The glass fragments were heated to 300-400 ℃ at a rate of 5-10 ℃ / min and held for 1.5 hours. Then, they were cooled to room temperature at the same rate. The glass fragments after vacuum annealing were manually broken into small pieces and placed in a ball mill with a ball-to-material ratio of 5:1-10:1. 10wt%-20wt% anhydrous ethanol was added and the milling was carried out at a speed of 200-400 rpm for 4-8 hours. The pieces were then dried and sieved.

[0013] Step S5. Quality Inspection: Test the glass transition temperature, softening temperature, particle size distribution, and chemical composition.

[0014] It should be noted that the preparation method of the high-strength, low-melting-point glass binder described in this application employs a melting-water quenching-vacuum annealing-ball milling process. By precisely controlling the parameters of each step, the high purity, uniformity, and excellent performance of the glass powder are ensured. In step S1, the raw material drying and preliminary mixing effectively remove moisture and volatiles, preventing bubble formation or component segregation due to water vapor during melting, and promoting the uniformity of subsequent reactions. In step S2, the material is heated in stages under a platinum crucible and air atmosphere. First, medium-temperature holding removes bubbles and low-melting-point volatiles, followed by high-temperature melting with intermittent stirring, promoting the full reaction and uniform distribution of components such as Bi₂O₃ and B₂O₃, forming a stable amorphous glass network, while simultaneously preventing Bi₂O₃ from being absorbed into the glass. 3+ The reduction process leads to color changes or performance degradation; Step S3, water quenching and rapid cooling, quickly solidifies the high-temperature glass melt into amorphous fragments. Thermal shock inhibits crystal precipitation and maintains low melting point characteristics. The resulting fragments are transparent or translucent, and the absence of bubbles indicates sufficient melting and a complete network structure. Step S4 introduces vacuum annealing, which, through gentle annealing under vacuum conditions, promotes the uniform distribution and local microcrystallization of CeO2 and ZrO2 in the glass network, forming a more stable nanoscale bridging structure. This improves the chemical stability and damp heat durability of the glass powder, reduces the bubble defect rate during subsequent sintering, and releases residual internal stress from the water quenching process, improving the structural stability of the glass fragments and preventing microcracks during subsequent crushing. Subsequently, by optimizing the ball-to-powder ratio, adding anhydrous ethanol as a dispersant, and controlling the rotation speed and time, fine crushing and anti-agglomeration are achieved, ultimately obtaining powder with uniform particle size, improving powder flowability and sintering activity. Step S5, quality inspection, ensures product consistency. Through the synergistic optimization of the above parameters, the modification effect of CeO2 and ZrO2 in the glass network is improved, which promotes the formation of more stable multi-element metal oxides during subsequent sintering. This significantly enhances the interfacial bonding strength and damp heat durability of the glass binder, making it particularly suitable for the low-temperature preparation and long-term reliable application of photovoltaic backsheet glass reflective coatings.

[0015] As a preferred technical solution for the application of a high-strength, low-melting-point glass adhesive in the reflective coating of photovoltaic backsheet glass, the high-strength, low-melting-point glass adhesive is mixed with pigments, organic carriers and functional additives to form a glass slurry, which is then applied to the surface of the photovoltaic backsheet glass and sintered and cured at 450-550℃ to form a reflective coating.

[0016] It should be noted that the coating is applied to the surface of the photovoltaic backsheet glass by means of screen printing or spraying, and then sintered and cured at a low temperature of 450-550℃ to form a dense, high-reflectivity coating, thereby significantly improving the back light utilization efficiency and damp heat durability of the photovoltaic module.

[0017] As a preferred technical solution for the application of a high-strength, low-melting-point glass adhesive in the reflective coating of photovoltaic backsheet glass, the glass slurry contains 50-70 parts of high-strength, low-melting-point glass adhesive, 20-40 parts of pigment, 5-15 parts of organic carrier, and 1-5 parts of functional additives.

[0018] It should be noted that in the glass slurry formulation described in this application, the proportion of high-strength, low-melting-point glass binder is 50-70 wt%, which serves as the main binder to ensure the density of the coating and the interfacial bonding strength. The proportion of pigment is 20-40 wt%, which provides high reflectivity. The proportion of organic carrier is 5-15 wt%, which adjusts the viscosity and printability of the slurry. The proportion of functional additives is 1-5 wt%, which improves the leveling and dispersibility. This formulation synergistically optimizes the slurry's workability and the reflectivity and damp heat durability of the coating after sintering.

[0019] As a preferred technical solution for the application of a high-strength, low-melting-point glass adhesive in the reflective coating of photovoltaic backsheet glass, the reflective coating has a thickness of 10-50 μm. Under the conditions of 85℃ / 85%RH humid heat aging, after 1000 hours of testing, the coating peeling rate is less than 5% and the reflectivity attenuation is less than 2%.

[0020] It should be noted that the thickness of the reflective coating described in this application is controlled at 10-50μm to optimize light reflection efficiency and mechanical strength. After 1000 hours of testing under harsh humid heat aging conditions of 85℃ / 85%RH, the coating peeling rate is less than 5% and the reflectivity decay is less than 2%. This excellent performance is due to the CeO2 and ZrO2-strengthened glass network and the stable multi-metal oxides formed, which effectively inhibit hydrolysis reaction and microcrack propagation. It is far superior to the durability of traditional low-melting-point glass systems and significantly improves the reliability and light utilization efficiency of photovoltaic backsheet glass under long-term high temperature and high humidity environments.

[0021] As a preferred technical solution for the application of a high-strength, low-melting-point glass adhesive in the reflective coating of photovoltaic backsheet glass, the sintering and curing process includes: a preheating stage of 200-300℃ for 20-30 minutes; a sintering stage of 450-550℃ for 30-60 minutes; and a cooling stage with a cooling rate of 10℃ / min.

[0022] It should be noted that the sintering and curing process described in this application adopts a staged temperature control process. In the preheating stage, the temperature is kept at 200-300℃ for 20-30 minutes to gradually remove organic carriers and additives, avoiding pores or cracks caused by rapid volatilization. In the sintering stage, the temperature is kept at 450-550℃ for 30-60 minutes to promote the full melting and flow of the glass binder, fix the pigments, and react with the photovoltaic glass substrate to form a stable multi-element metal oxide, achieving a dense high-reflectivity coating. In the cooling stage, the cooling rate is controlled within 10℃ / min to alleviate thermal stress and prevent the generation of microcracks. These process parameters synergistically optimize the uniformity, adhesion, and damp heat durability of the coating, are compatible with existing photovoltaic glass heat treatment equipment, and ensure the high reliability and excellent optical performance of the reflective coating under long-term high temperature and high humidity environments.

[0023] Compared with existing low-melting-point glass adhesives, this application, by synergistically introducing SiO2, Al2O3, and multi-component oxide components such as CeO2 and ZrO2 into the Bi2O3-B2O3-ZnO system, significantly improves the cross-linking density and chemical stability of the glass network while maintaining a low glass transition temperature and softening temperature and meeting the requirements of low-temperature sintering processes of 450–550 °C. This allows the sintered coating to form a more stable multi-component metal-oxygen bridging structure on the surface of the photovoltaic glass substrate, thereby effectively enhancing the interfacial bonding strength and suppressing hydration, structural relaxation, and microcrack propagation under humid and hot conditions. Combined with vacuum annealing and fine ball milling processes, the uniformity of the glass powder and the sintering densification behavior are further improved, enabling the resulting reflective coating to maintain a low peeling rate and reflectivity decay even under long-term aging conditions of 85 °C / 85%RH. This significantly improves the long-term reliability, environmental durability, and optical stability of the photovoltaic backsheet glass reflective coating, demonstrating good process adaptability and engineering application value. Attached Figure Description

[0024] Figure 1 The XPS full spectrum of the coating after sintering in Example 1;

[0025] Figure 2 The O 1s high-resolution XPS spectrum of the coating after sintering in Example 1;

[0026] Figure 3 The high-resolution XPS spectrum of Bi4f after coating sintering in Example 1;

[0027] Figure 4 The XRD patterns are of the sintered coatings of Example 1 and Comparative Examples 1 to 3. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0031] Example

[0032] Example 1

[0033] This embodiment provides a high-strength, low-melting-point glass adhesive, its preparation method, and its application.

[0034] Composition: By weight, Bi2O3 40 parts, B2O3 15 parts, ZnO 10 parts, SiO2 8 parts, Al2O3 5 parts, CeO2 3 parts, ZrO2 1 part, CaF2 1 part.

[0035] Preparation method:

[0036] Step S1. Raw material preparation: Accurately weigh high-purity (≥99.5%) Bi2O3, B2O3, ZnO, SiO2, Al2O3, CeO2, ZrO2 and CaF2 raw materials according to the above weight proportions, using a precision electronic balance with an error not exceeding 0.1%; place all raw materials in a 120℃ oven to dry for 3 hours to fully remove moisture and volatiles, then transfer to a V-type mixer and stir at low speed for 45 minutes to ensure uniform color and no obvious agglomeration;

[0037] Step S2. Melting process: Transfer the uniformly mixed raw materials to a platinum crucible and place it in a muffle furnace with an air atmosphere. Heat the material to 900°C at a heating rate of 6°C / min and hold for 45 minutes to remove bubbles and low-melting-point volatiles. Then continue heating to 1200°C and hold for 3 hours. Stir with a platinum rod for 5-10 minutes every 30 minutes to promote full reaction and uniform distribution of the components, forming a uniform glass melt with a suitable viscosity. At the same time, monitor to avoid excessive volatilization.

[0038] Step S3. Water quenching into blocks: After melting, quickly pour the molten glass into 10℃ deionized water (the volume of water is 8 times the volume of the molten glass) for water quenching, which produces a rapid cooling effect to form amorphous glass fragments; after quenching, collect the fragments, filter them with a sieve, and dry them in a 90℃ oven for 1.5 hours. Check the appearance of the fragments; they should be transparent or translucent, without obvious bubbles or unmelted particles.

[0039] Step S4. Vacuum annealing treatment - ball milling: Place the dried glass fragments in a vacuum furnace (vacuum degree ≤ 10). -3 The glass fragments were heated to 350℃ at a rate of 7℃ / min and held for 1.5 hours. Then, they were cooled to room temperature at the same rate. The glass fragments after vacuum annealing were manually broken into small pieces and placed in a planetary ball mill. Zirconia balls were used as the grinding medium at a ball-to-material ratio of 5:1. Anhydrous ethanol (10 wt% of the fragment weight) was added as a dispersant to prevent agglomeration. The mixture was first dry-milled for 1 hour, then wet-milled at 200 rpm for 8 hours. After ball milling, the grinding medium was filtered to separate the slurry. The slurry was dried in a vacuum drying oven (70℃, vacuum degree -0.08MPa) for 2 hours to obtain fine powder. Finally, the powder was passed through a 300-mesh sieve to remove large particles.

[0040] Step S5. Quality inspection: Test the glass transition temperature and softening temperature of the obtained glass powder.

[0041] Specific applications:

[0042] The aforementioned high-strength, low-melting-point glass binder was mixed with pigments, organic carriers, and functional additives to prepare a glass slurry. The glass slurry, by weight, comprised: 60 parts of high-strength, low-melting-point glass binder, 30 parts of TiO2 pigment, 8 parts of organic carrier (ethyl cellulose dissolved in terpineol), and 2 parts of functional additives (dispersant and leveling agent). After uniform mixing, the slurry was screen-printed onto the surface of a photovoltaic backsheet glass, controlling the coating thickness to 20 μm. It was then sintered and cured at 450-550℃ to form a reflective coating. The specific sintering and curing process included: a preheating stage at 250℃ for 25 minutes; a sintering stage at 500℃ for 45 minutes; and a cooling stage with a cooling rate of 10℃ / min.

[0043] Example 2

[0044] This embodiment provides a high-strength, low-melting-point glass adhesive, its preparation method, and its application.

[0045] Composition: By weight, Bi2O3 50 parts, B2O3 20 parts, ZnO 5 parts, SiO2 5 parts, Al2O3 3 parts, CeO2 1 part, ZrO2 3 parts, CaF2 0.5 parts, TiO2 3 parts, MgO 0.5 parts.

[0046] Preparation method:

[0047] Step S1. Raw material preparation: Accurately weigh high-purity (≥99.5%) Bi2O3, B2O3, ZnO, SiO2, Al2O3, CeO2, ZrO2, CaF2, TiO2 and MgO raw materials according to the above weight proportions, using a precision electronic balance with an error not exceeding 0.1%; place all raw materials in a 120℃ oven and dry for 2.5 hours to fully remove moisture and volatiles, then transfer to a V-type mixer and stir at low speed for 40 minutes to ensure uniform color and no obvious agglomeration;

[0048] Step S2. Melting process: Transfer the uniformly mixed raw materials to a platinum crucible and place it in a muffle furnace with an air atmosphere; raise the temperature to 800°C at a rate of 5°C / min and hold for 50 minutes to remove bubbles and low-melting-point volatiles; then continue to raise the temperature to 1280°C and hold for 2.5 hours, stirring with a platinum rod for 5-10 minutes every 40 minutes to promote full reaction and uniform distribution of components, forming a uniform glass melt with appropriate viscosity, while monitoring to avoid excessive volatilization;

[0049] Step S3. Water quenching into blocks: After melting, quickly pour the molten glass into 12°C deionized water (the volume of water is 7 times the volume of the molten glass) for water quenching, which produces a rapid cooling effect to form amorphous glass fragments; after quenching, collect the fragments, filter them with a sieve, and dry them in a 95°C oven for 1.2 hours; check the appearance of the fragments, which should be transparent or translucent, without obvious bubbles or unmelted particles;

[0050] Step S4. Vacuum annealing treatment - ball milling: Place the dried glass fragments in a vacuum furnace (vacuum degree ≤ 10). -3 The glass fragments were heated to 300℃ at a rate of 5℃ / min and held for 2 hours. Then, they were cooled to room temperature at the same rate. The glass fragments after vacuum annealing were manually broken into small pieces and placed in a planetary ball mill. Zirconia balls were used as the grinding medium at a ball-to-material ratio of 7:1. Anhydrous ethanol, accounting for 12wt% of the weight of the fragments, was added as a dispersant to prevent agglomeration. The milling was first dry-milled for 1.5 hours, followed by wet-milling at 350 rpm for 5.5 hours. After the ball milling was completed, the grinding medium was filtered to separate the milling medium. The slurry was dried in a vacuum drying oven (75℃, vacuum degree -0.08MPa) for 1.5 hours to obtain fine powder. Finally, the powder was passed through a 250-mesh sieve to remove large particles.

[0051] Step S5. Quality inspection: Test the glass transition temperature and softening temperature of the obtained glass powder.

[0052] Specific applications:

[0053] The high-strength, low-melting-point glass binder is mixed with pigments, organic carriers, and functional additives to form a glass slurry. The glass slurry, by weight, comprises: 55 parts high-strength, low-melting-point glass binder, 35 parts TiO2 pigment, 7 parts organic carrier (ethyl cellulose dissolved in terpineol), and 3 parts functional additives (dispersant and leveling agent). After uniform mixing, the slurry is sprayed onto the surface of the photovoltaic backsheet glass, controlling the coating thickness to 30 μm, and then sintered and cured at 450-550℃ to form a reflective coating. The specific sintering and curing process includes: a preheating stage at 220℃ for 28 minutes; a sintering stage at 480℃ for 50 minutes; and a cooling stage with a cooling rate of 10℃ / min.

[0054] Example 3

[0055] This embodiment provides a high-strength, low-melting-point glass adhesive, its preparation method, and its application.

[0056] Composition: By weight, Bi2O3 55 parts, B2O3 18 parts, ZnO 8 parts, SiO2 7 parts, Al2O3 4 parts, CeO2 4 parts, ZrO2 1.5 parts, CaF2 0.8 parts, TiO2 0.5 parts.

[0057] Preparation method:

[0058] Step S1. Raw material preparation: Accurately weigh high-purity (≥99.5%) Bi2O3, B2O3, ZnO, SiO2, Al2O3, CeO2, ZrO2, CaF2 and TiO2 raw materials according to the above weight proportions, using a precision electronic balance with an error not exceeding 0.1%; place all raw materials in a 120℃ oven to dry for 3.5 hours to fully remove moisture and volatiles, and then transfer them to a V-type mixer and stir at low speed for 50 minutes to ensure uniform color and no obvious agglomeration.

[0059] Step S2. Melting process: Transfer the uniformly mixed raw materials to a platinum crucible and place it in a muffle furnace with an air atmosphere; raise the temperature to 950°C at a heating rate of 6°C / min and hold for 40 minutes to remove bubbles and low-melting-point volatiles; then continue to raise the temperature to 1350°C and hold for 3.5 hours, stirring with a platinum rod for 5-10 minutes every 35 minutes to promote full reaction and uniform distribution of components, forming a uniform glass melt with appropriate viscosity;

[0060] Step S3. Water quenching into blocks: After melting, quickly pour the molten glass into 18°C ​​deionized water (the volume of water is 9 times the volume of the molten glass) for water quenching, which produces a rapid cooling effect to form amorphous glass fragments; after quenching, collect the fragments, filter them with a sieve, and dry them in an 85°C oven for 1.8 hours; check the appearance of the fragments, which should be transparent or translucent, without obvious bubbles or unmelted particles;

[0061] Step S4. Vacuum annealing treatment - ball milling: Place the dried glass fragments in a vacuum furnace (vacuum degree ≤ 10). -3 The glass fragments were heated to 400℃ at a rate of 10℃ / min and held for 1 hour. Then, they were cooled to room temperature at the same rate. The glass fragments after vacuum annealing were manually broken into small pieces and placed in a planetary ball mill. Zirconia balls were used as the grinding medium at a ball-to-material ratio of 9:1. Anhydrous ethanol, accounting for 18wt% of the weight of the fragments, was added as a dispersant to prevent agglomeration. The mills were first dry-milled for 0.5 hours, then wet-milled at 250 rpm for 7 hours. After the ball milling was completed, the grinding medium was filtered to separate the milling medium. The slurry was dried in a vacuum drying oven (65℃, vacuum degree -0.08MPa) for 2.5 hours to obtain fine powder. Finally, the powder was passed through a 350-mesh sieve to remove large particles.

[0062] Step S5. Quality inspection: Test the glass transition temperature and softening temperature of the obtained glass powder.

[0063] Specific applications:

[0064] The high-strength, low-melting-point glass binder is mixed with pigments, organic carriers, and functional additives to prepare a glass slurry. The glass slurry, by weight, comprises: 65 parts high-strength, low-melting-point glass binder, 25 parts TiO2 pigment, 8 parts organic carrier (ethyl cellulose dissolved in terpineol), and 2 parts functional additives (dispersant and leveling agent). After uniform mixing, the slurry is applied to the surface of a photovoltaic backsheet glass via screen printing, controlling the coating thickness to 15 μm. It is then sintered and cured at 450-550℃ to form a reflective coating. The specific sintering and curing process includes: a preheating stage at 280℃ for 22 minutes; a sintering stage at 520℃ for 40 minutes; and a cooling stage with a cooling rate of 10℃ / min.

[0065] Example 4

[0066] This embodiment provides a high-strength, low-melting-point glass adhesive, its preparation method, and its application.

[0067] Composition: By weight, Bi2O3 60 parts, B2O3 10 parts, ZnO 15 parts, SiO2 10 parts, Al2O3 8 parts, CeO2 5 parts, ZrO2 4 parts, CaF2 2 parts, MgO 2 parts.

[0068] Preparation method:

[0069] Step S1. Raw material preparation: Accurately weigh high-purity (≥99.5%) Bi2O3, B2O3, ZnO, SiO2, Al2O3, CeO2, ZrO2, CaF2 and MgO raw materials according to the above weight proportions, using a precision electronic balance with an error not exceeding 0.1%; place all raw materials in a 120℃ oven to dry for 4 hours to fully remove moisture and volatiles, then transfer to a V-type mixer and stir at low speed for 60 minutes to ensure uniform color and no obvious agglomeration;

[0070] Step S2. Melting process: Transfer the uniformly mixed raw materials to a platinum crucible and place it in a muffle furnace with an air atmosphere; raise the temperature to 1000°C at a rate of 10°C / min and hold for 60 minutes to remove bubbles and low-melting-point volatiles; then continue to raise the temperature to 1400°C and hold for 4 hours, stirring with a platinum rod for 5-10 minutes every 30 minutes to promote full reaction and uniform distribution of components, forming a uniform glass melt with appropriate viscosity, while monitoring to avoid excessive volatilization;

[0071] Step S3. Water quenching into blocks: After melting, quickly pour the molten glass into 20°C deionized water (the volume of water is 10 times the volume of the molten glass) for water quenching, which produces a rapid cooling effect to form amorphous glass fragments; after quenching, collect the fragments, filter them with a sieve, and dry them in a 100°C oven for 2 hours; check the appearance of the fragments, which should be transparent or translucent, without obvious bubbles or unmelted particles;

[0072] Step S4. Vacuum annealing treatment - ball milling: Place the dried glass fragments in a vacuum furnace (vacuum degree ≤ 10). -3 The glass fragments were heated to 350℃ at a rate of 5℃ / min and held for 1.5 hours. Then, they were cooled to room temperature at the same rate. The glass fragments after vacuum annealing were manually broken into small pieces and placed in a planetary ball mill. Zirconia balls were used as the grinding medium at a ball-to-material ratio of 10:1. Anhydrous ethanol (20 wt% of the fragment weight) was added as a dispersant to prevent agglomeration. The mixture was first dry-milled for 2 hours, then wet-milled at 400 rpm for 8 hours. After ball milling, the grinding medium was filtered to separate the slurry. The slurry was dried in a vacuum drying oven (80℃, vacuum degree -0.08 MPa) for 3 hours to obtain fine powder. Finally, the powder was passed through a 400-mesh sieve to remove large particles.

[0073] Step S5. Quality inspection: Test the glass transition temperature and softening temperature of the obtained glass powder.

[0074] Specific applications:

[0075] The high-strength, low-melting-point glass binder is mixed with pigments, organic carriers, and functional additives to prepare a glass slurry. The glass slurry, by weight, comprises: 50 parts high-strength, low-melting-point glass binder, 40 parts TiO2 pigment, 6 parts organic carrier (ethyl cellulose dissolved in terpineol), and 4 parts functional additives (dispersant and leveling agent). After uniform mixing, the slurry is sprayed onto the surface of a photovoltaic backsheet glass, controlling the coating thickness to 40 μm, and then sintered and cured at 450-550℃ to form a reflective coating. The specific sintering and curing process includes: a preheating stage at 200℃ for 30 minutes; a sintering stage at 450℃ for 60 minutes; and a cooling stage with a cooling rate of 10℃ / min.

[0076] Comparison Example

[0077] Compare with Example 1

[0078] The difference from Example 1 is that CeO2 is not added; that is, the composition, by weight, is: 43 parts Bi2O3, 15 parts B2O3, 10 parts ZnO, 8 parts SiO2, 5 parts Al2O3, 1 part ZrO2, and 1 part CaF2. The preparation method and specific application are the same as in Example 1.

[0079] Compare with Example 2

[0080] The difference from Example 1 is that ZrO2 is not added. The composition, by weight, is: Bi2O3 41 parts, B2O3 15 parts, ZnO 10 parts, SiO2 8 parts, Al2O3 5 parts, CeO2 3 parts, and CaF2 1 parts. The preparation method and specific applications are the same as in Example 1.

[0081] Compare with Example 3

[0082] The difference from Example 1 is that CaF2 is not added. The composition, by weight, is: Bi2O3 41 parts, B2O3 15 parts, ZnO 10 parts, SiO2 8 parts, Al2O3 5 parts, CeO2 3 parts, and ZrO2 1 part. The specific application is the same as in Example 1.

[0083] Compare with Example 4

[0084] The difference from Example 1 is that the components are the same, the blocks are water-quenched without vacuum annealing, and are directly manually broken into small pieces. The specific application is the same as in Example 1.

[0085] Performance testing

[0086] 1. Test method for glass transition temperature

[0087] The glass transition temperature (Tg) was measured using differential scanning calorimetry (DSC). A 20 mg glass powder sample was placed in an aluminum sample pan and heated from room temperature to 600 °C at a heating rate of 10 °C / min under a nitrogen atmosphere. The heat flow curve was recorded.

[0088] 2. Test method for softening temperature

[0089] The softening temperature (Ts) was measured using a thermomechanical analyzer (TMA). The glass powder was pressed into a standard rod-shaped sample (e.g., 25 mm in length and 5 mm in diameter), and a constant stress was applied at a heating rate of 5 °C / min in air. The deformation curve of the sample was then monitored.

[0090] 3. Test method for coating peel rate

[0091] The coating peel rate was tested using a cross-cut test combined with image analysis after damp heat aging. First, the coating sample was placed in a constant temperature and humidity chamber and aged for 1000 hours at 85℃ and 85% relative humidity. After aging, a 10x10 grid (2mm spacing) was cut on the coating surface using a cross-cut tester, standard adhesive tape (such as 3M Scotch tape) was applied and quickly peeled off, and the proportion of peeled grids to the total grid was counted using an optical microscope to calculate the peel rate.

[0092] 4. Test method for reflectivity attenuation

[0093] Reflectance decay was tested using a UV-Vis-NIR spectrophotometer after humid heat aging. The sample was placed under 85℃ / 85%RH conditions for 1000 hours of aging, and the diffuse reflectance spectrum in the wavelength range of 400-1100nm was measured. Scattered light was collected using an integrating sphere, and the average reflectance was calculated. The decay value was the percentage of the difference in reflectance before and after aging.

[0094] Table 1

[0095]

[0096] In conjunction with Example 1 and Figures 1 to 3It can be seen that the surface of the coating in Example 1 after sintering is mainly composed of Bi, Zn, Si, B, Al, Ce, Zr, Ca, and O elements, and the characteristic peak positions of each element are consistent with their stable oxidation states, with no metallic peaks appearing. This indicates that the sintering process promotes the full oxidation of each component and forms a stable inorganic oxide glass structure. Among them, the O 1s high-resolution spectrum can be decomposed into a main peak of about 530.0 eV and a secondary peak of about 531.6 eV. The former corresponds to the metal-oxygen bonds in the glass framework such as Bi–O and Si–O, while the latter is related to the oxygen coordination environment containing Ce, Zr, and B, reflecting the modulation effect of rare earth and high-valence metal oxides on the glass network structure. The binding energies of Bi 4f, Zn 2p, Si 2p, B 1s, and Al 2p are all within the typical oxide range, indicating that each oxide maintains good chemical stability during sintering. The appearance of characteristic peaks for Ce 3d and Zr 3d further confirms that Ce and Zr are uniformly distributed in the coating in their oxidized forms. XPS results show that after sintering, Example 1 formed a dense glass network structure composed of multiple metal oxides, which is consistent with the improved interfacial bonding strength and structural stability under humid and hot conditions.

[0097] like Figure 4 As shown, the XRD results of Example 1 and Comparative Examples 1-3 indicate that all coatings are dominated by an amorphous glass phase after sintering, but their structural stability varies significantly. Example 1 exhibits the broadest diffuse peak in the range of 2θ≈20°-35°, with almost no sharp diffraction peaks, indicating the formation of a highly vitrified amorphous structure after sintering. This result is consistent with the characteristics of each element existing in a stable oxidation state in XPS and the presence of a multi-metal-oxygen coordination environment in O 1s, suggesting that glass framework oxides such as Bi, Si, and B, along with high-valence metal oxides such as Ce and Zr, synergistically construct a stable oxide glass network. In contrast, the XRD dispersion peaks of Comparative Examples 1-3 gradually narrowed, and weak diffraction characteristics of varying degrees appeared in the 2θ≈27°–31° region, reflecting that in the absence of CeO2, ZrO2, or CaF2, the stability of the glass network decreased, and local ordering or microcrystalline structures were more easily formed; this corresponds to the relatively simple oxygen coordination environment and weakened network modulation effect reflected by XPS. The above results indicate that Example 1 effectively suppressed the crystallization behavior during sintering through the synergistic effect of multiple oxides, significantly improving the stability of the coating structure.

[0098] As can be seen from Examples 1 to 4 and Table 1, the glass transition temperature Tg of Examples 1 to 4 is in the range of 377 to 422 ℃, and the softening temperature Ts is in the range of 426 to 479 ℃. This indicates that the low melting point glass binder system maintains good thermal stability while keeping the softening temperature low. At the same time, the initial reflectivity of the coating is controlled at a low level of 2.4% to 4.1%, and the reflectivity decay rate is 0.7% to 1.9%, with small overall fluctuations. This shows that different examples can still form a stable and consistent coating structure after formula adjustment, and have good process stability and performance repeatability.

[0099] Combining Example 1, Comparative Example 1, and Table 1, it can be seen that the Tg of Comparative Example 1 is 372 °C and the Ts is 429 °C, which are similar to those of Example 1. However, the initial reflectivity of its coating increases to 8.4%, and the reflectivity attenuation rate increases to 3.6%, which is significantly higher than the 2.5% and 1.3% of Example 1. This indicates that although Comparative Example 1 has a certain foundation in thermal performance, due to the lack of the synergistic regulatory effect of the multi-component oxides in Example 1, it is difficult to form a dense and uniform inorganic glass network structure after sintering, resulting in a decrease in the optical uniformity and environmental stability of the coating surface, thus exhibiting higher reflectivity and more severe aging attenuation.

[0100] Combining Example 1, Comparative Example 2, and Table 1, it can be seen that the Tg of Comparative Example 2 is 384 °C and the Ts is 435 °C, which is not significantly different from that of Example 1. However, the initial reflectivity of its coating is increased to 7.9%, and the reflectivity attenuation rate is 2.8%, both significantly higher than that of Example 1. This indicates that due to the lack of key structural modulation components, the cross-linking degree and structural stability of the glass network in Comparative Example 2 are insufficient, making it more prone to microstructural inhomogeneity or interface defects during sintering and subsequent aging, thereby weakening the anti-reflection effect and long-term stability of the coating.

[0101] Combining Example 1, Comparative Example 3, and Table 1, it can be seen that the Tg and Ts of Comparative Example 3 are 379 ℃ and 432 ℃, respectively, but its initial reflectivity is as high as 9.5%, and the reflectivity attenuation rate reaches 3.9%, which is the highest level among all samples. This result indicates that, in the absence of the appropriate flux and network stabilizing components used in Example 1, although the glass system can still soften at a lower temperature, the insufficient fluidity and spreadability of the glass phase during sintering leads to poor coating density and increased structural defects, thereby significantly deteriorating optical performance and aging resistance.

[0102] Combining Example 1, Comparative Example 4, and Table 1, it can be seen that the Tg and Ts of Comparative Example 4 are 384 ℃ and 433 ℃, respectively, which are at a moderate level. Its initial reflectivity is 6.5%, and its reflectivity decay rate is 2.5%, which is lower than that of Comparative Examples 1-3, but still significantly higher than that of Example 1. This result shows that it is difficult to simultaneously achieve low reflectivity and aging resistance stability of the coating by simply adjusting local components or optimizing a single performance. In contrast, Example 1, through the synergistic design of the multi-element oxide system, makes the glass network structure more uniform and dense, thereby achieving a better balance between optical performance and long-term stability.

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength, low-melting-point glass adhesive, characterized in that, The high-strength, low-melting-point glass adhesive comprises the following components by weight: 40-60 parts Bi2O3, 10-20 parts B2O3, 5-15 parts ZnO, 5-10 parts SiO2, 3-8 parts Al2O3, 1-5 parts CeO2, 1-4 parts ZrO2, and 0.5-2 parts CaF2; the glass transition temperature of the high-strength, low-melting-point glass adhesive is 350-450℃, and the softening temperature is 400-500℃.

2. The high-strength, low-melting-point glass adhesive according to claim 1, characterized in that, It also includes 0.5-3 parts TiO2 and / or 0.5-2 parts MgO by weight.

3. The method for preparing the high-strength, low-melting-point glass adhesive according to claim 1, characterized in that, Includes the following steps: Step S1. Raw material preparation: Weigh each component raw material according to the weight parts, dry them at 120℃ for 2-4 hours to remove moisture, and mix all raw materials evenly in the preliminary stage; Step S2. Melting process: Place the mixed raw materials in a platinum crucible, and in an air atmosphere, first heat to 800-1000℃ at 5-10℃ / min, hold for 30-60 minutes to remove air bubbles, then heat to 1200-1400℃, hold for 2-4 hours, and stir intermittently to form a uniform glass melt. Step S3. Water quenching into blocks: Pour the molten glass into deionized water at 10-20℃ for water quenching to form glass fragments. After drying, check that the glass is transparent or translucent and free of bubbles. Step S4. Vacuum annealing treatment - ball milling: Place the dried glass fragments in a vacuum furnace (vacuum degree ≤ 10). -3 The glass fragments were heated to 300-400 ℃ at a rate of 5-10 ℃ / min and held for 1.5 hours. Then, they were cooled to room temperature at the same rate. The glass fragments after vacuum annealing were manually broken into small pieces and placed in a ball mill with a ball-to-material ratio of 5:1-10:

1. 10wt%-20wt% anhydrous ethanol was added and the milling was carried out at a speed of 200-400 rpm for 4-8 hours. The pieces were then dried and sieved. Step S5. Quality Inspection: Test the glass transition temperature, softening temperature, particle size distribution, and chemical composition.

4. The application of the high-strength, low-melting-point glass adhesive according to claim 1 in the reflective coating of photovoltaic backsheet glass, characterized in that, The high-strength, low-melting-point glass adhesive is mixed with pigments, organic carriers, and functional additives to form a glass slurry, which is then applied to the surface of the photovoltaic backsheet glass and sintered and cured at 450-550℃ to form a reflective coating.

5. The application according to claim 4, characterized in that, The glass slurry contains 50-70 parts of high-strength, low-melting-point glass binder, 20-40 parts of pigment, 5-15 parts of organic carrier, and 1-5 parts of functional additives.

6. The application according to claim 5, characterized in that, The reflective coating has a thickness of 10-50 μm. After 1000 hours of testing under 85℃ / 85%RH humid heat aging conditions, the coating peeling rate is less than 5% and the reflectivity attenuation is less than 2%.

7. The application according to claim 6, characterized in that, The sintering and solidification process includes: a preheating stage at 200-300℃ for 20-30 minutes; a sintering stage at 450-550℃ for 30-60 minutes; and a cooling stage with a cooling rate of 10℃ / min.

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