Composition for transfer printing, preparation method of composition and preparation method of electrode grid line

Abstract

The invention relates to a composition for transfer printing and a preparation method and application thereof, and relates to the technical field of photovoltaic cell manufacturing, and the composition for transfer printing comprises the following components by mass: 3-20% of polyethylene glycol; 0.05 to 10% of a plasticizer; 1-15% of a coalescing agent; 0.01 to 2 percent of a surfactant; 0.5-1% of a pore forming agent; 0.01 to 1% of a cross-linking agent; 0.01%-0.5% of a release agent; 0.01%-0.5% of a flatting agent; and the balance of water. By optimizing the proportion of all the components, the requirement for rapid film removal is met, the strength and integrity of the film are guaranteed, and the production efficiency and quality are improved; the polyethylene glycol has good water solubility and biocompatibility, and does not react with the conductive slurry or the silicon wafer; the plasticizer enhances the flexibility and stability of the film, avoids rupture and keeps the pattern intact; the coalescing agent improves the surface smoothness, strength and water resistance of the film and improves the stability; an organic solvent is replaced by a water solvent, so that the environmental protection property is higher, environmental and operation hazards are reduced, and green production requirements are met.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic cell manufacturing, and in particular to a composition for transfer printing, a preparation method thereof, and an electrode grid line preparation method. Background Art

[0002] In the production of photovoltaic cells, electrode grid lines are a key component for current collection and conduction. The quality of their preparation directly affects the photoelectric conversion efficiency and stability of the cell. Currently, common methods for preparing electrode grid lines include screen printing and electroplating.

[0003] Screen printing is the most widely used technology, offering advantages such as simplicity and suitability for large-scale production. However, as photovoltaic cell efficiency increases, the demand for finer grid lines is also increasing. Traditional screen printing faces precision limitations, making it difficult to meet the demand for finer and more precise grid lines. Furthermore, silver paste waste and screen stencil wear increase production costs and affect efficiency.

[0004] Electroplating offers certain advantages in terms of precision and material waste control, but the process is complex and requires precise control of parameters such as the composition, concentration, temperature, and current density of the plating solution, placing high demands on both equipment and operators. Furthermore, the chemical liquids used in the electroplating process contain hazardous substances, potentially polluting the environment. Furthermore, the electroplating process can damage the silicon wafer surface, thereby affecting the performance of photovoltaic cells.

[0005] In recent years, some studies have begun to try to use water-soluble films as carriers of electrode grid lines, aiming to improve production efficiency and reduce material waste. Although water-soluble films have certain advantages in the film removal process, the problems they have cannot be ignored. The dissolution time of some water-soluble films is too long, which affects the production rhythm, while the dissolution time is too short, which may cause the film to dissolve prematurely during the transfer process, affecting the quality. In addition, some water-soluble films contain harmful substances, which may pose a potential threat to the environment and human health. At the same time, they may react chemically with silicon wafers or silver paste during the transfer process, resulting in performance degradation. The mechanical properties of water-soluble films are poor, and they are easily deformed or broken during the transfer process, affecting the integrity of the grid line pattern.

[0006] Therefore, although the existing technology has solved some problems in the preparation of electrode grid lines to a certain extent, it still faces challenges in terms of accuracy, efficiency, cost and environmental protection, and there is an urgent need to develop a more efficient and environmentally friendly preparation method. Summary of the Invention

[0007] In order to solve the problems that existing water-soluble films will chemically react with silicon wafers or silver paste, and that the films take a long time to dissolve in water, have poor environmental protection, and have poor mechanical properties, the present application provides a composition for transfer, a preparation method thereof, and an electrode grid line preparation method.

[0008] The following technical solutions are adopted: A composition for transfer printing comprises the following components, calculated by mass percentage: polyethylene glycol: 3-20%; plasticizer: 0.05-10%; film-forming aid: 1-15%; surfactant: 0.01-2%; pore-forming agent: 0.5-1%; cross-linking agent: 0.01-1%; release agent: 0.01-0.5%; leveling agent: 0.01-0.5%; and the balance is water.

[0009] By adopting the above-mentioned technical scheme, the composition for transfer of the present application can realize efficient and environmentally friendly electrode grid line transfer applications; by reasonably selecting the ratio of low molecular weight to high molecular weight of polyethylene glycol, plasticizers, film-forming aids and other ingredients, the dissolution rate, mechanical strength, flexibility and chemical stability of the film are optimized; the film can be quickly dissolved and has good stability, ensuring that the quality of the electrode grid line is not affected after the film removal process, and through the addition of surfactants, pore-forming agents and cross-linking agents, the surface properties, pore structure and mechanical properties of the film are significantly improved, thereby improving the environmental protection, production efficiency and adaptability of the film material.

[0010] In a specific embodiment, the polyethylene glycol includes low molecular weight polyethylene glycol and high molecular weight polyethylene glycol, and the mass ratio of the low molecular weight polyethylene glycol to the high molecular weight polyethylene glycol is 1:(0.1-10.0).

[0011] By adopting this technical solution, the flexibility of low-molecular-weight polyethylene glycol allows the film to better adapt to different shapes and surfaces during removal and is less prone to cracking. High-molecular-weight polyethylene glycol increases the film's mechanical strength, making it more resistant to stretching, compression, and tearing when subjected to stress, thereby improving the film's overall mechanical properties. By optimizing the ratio of low-molecular-weight to high-molecular-weight polyethylene glycol, the film's dissolution rate, mechanical properties, and stability can be precisely controlled, making it more adaptable to the needs of different production processes.

[0012] In a specific embodiment, the average molecular weight of the low molecular weight polyethylene glycol is 600-4000, and the average molecular weight of the high molecular weight polyethylene glycol is 10000-100000.

[0013] By adopting the above technical solution, using a combination of low molecular weight polyethylene glycol (600-4000) and high molecular weight polyethylene glycol (10000-100000), better dissolution control, enhanced mechanical properties and stability can be achieved in film materials, while improving environmental performance.

[0014] In a specific embodiment, the plasticizer is one or more of polyols and polyol ethers.

[0015] By adopting the above technical solution and using plasticizers, not only the flexibility, solubility, mechanical properties and water solubility of the film are optimized, but also the biodegradability and environmental performance of the film are improved.

[0016] In a specific embodiment, the film-forming aid includes one or more of polyvinyl pyrrolidone, polyvinyl alcohol, carboxymethyl cellulose, gelatin, polyacrylamide, polypropylene glycol and derivatives thereof.

[0017] By adopting the above technical solution, the formula can improve the flexibility, solubility, mechanical strength, transparency and stability of the film by adding the above film-forming aid, while ensuring that the film has good biodegradability and environmental protection.

[0018] In a specific embodiment, the surfactant includes one or more of polyoxyethylene ethers, alkyl glycosides, fatty acid methyl ester sulfonates, soybean lecithin and alkyl alcohol amides.

[0019] By adopting the above technical solution, the above surfactant has the ability to reduce the interfacial tension between liquid and solid, and between liquid and liquid, and can improve the wettability and fluidity of the solution, making the PEG solution easier to apply and spread, and improving the uniformity and quality of the film formation; by adjusting the type and content of the surfactant, the flexibility, tensile strength, hygroscopicity and water solubility of the PEG film can be improved.

[0020] In a specific embodiment, the pore-forming agent is one or more of ammonium bicarbonate, ammonium chloride, hydrogen peroxide, and azodicarbonamide.

[0021] By adopting the above-mentioned technical solution and using these pore-forming agents, a pore structure can be created in the film, significantly increasing the contact area between the membrane and water, thereby accelerating the speed at which water passes through the membrane; at the same time, the role of the pore-forming agent can also promote the disintegration process of the membrane, effectively avoiding scaling and clogging problems of the membrane, and improving the overall performance and service life of the membrane.

[0022] In a specific embodiment, the cross-linking agent is one or more of glutaraldehyde, dopamine, and diamino compounds.

[0023] By adopting the above-mentioned technical solution and using the above-mentioned green cross-linking agent, the mechanical properties and durability of the membrane can be significantly enhanced, and the anti-pollution ability and thermal stability of the membrane can be improved; at the same time, the green cross-linking agent has advantages in environmental protection, meets the needs of sustainable development, and can improve the performance of membrane materials and reduce environmental impact.

[0024] In a specific embodiment, the release agent includes one or more of polyethylene glycol derivatives, silane coupling agents, fatty acid salts, and composite emulsification systems.

[0025] By adopting the above technical solution, the above-mentioned release agent can improve the demoulding performance, reduce the adhesion of residues on the mold surface, and improve production efficiency. At the same time, it has excellent lubricity, interfacial activity and dispersibility, is suitable for the demoulding requirements of different materials, and provides a more stable and efficient demoulding effect.

[0026] In a specific embodiment, the leveling agent includes one or more of an organosilicon-modified leveling agent and a non-silicone leveling agent.

[0027] By adopting the above technical solution, the above-mentioned leveling agent can improve the leveling and flatness of the coating, reduce surface defects such as bubbles and brush marks, enhance the gloss and uniformity of the coating, and at the same time improve the adhesion and weather resistance of the coating, thereby extending the service life of the product.

[0028] A method for preparing a composition for transfer printing comprises the following steps: Disperse polyethylene glycol in water and stir until completely dissolved; Add film-forming aid, surfactant and plasticizer in sequence and perform homogenization; Then add a crosslinking agent, a pore-forming agent, a release agent, and a leveling agent to carry out a crosslinking and foaming reaction, heat at 50-70°C for 5-15 minutes to ensure that the components in the solution are fully dissolved, and then dry at 40-60°C to obtain a composition for transfer.

[0029] The weight percentages of the components are as follows: polyethylene glycol: 3-20%; plasticizer: 0.05-10%; film-forming aid: 1-15%; surfactant: 0.01-2%; pore-forming agent: 0.5-1%; cross-linking agent: 0.01%-1%; release agent: 0.01-0.5%; leveling agent: 0.01-0.5%; and the balance is water.

[0030] By adopting the above-mentioned technical solution, the components used in this application are all biodegradable and meet environmental protection requirements, so that the film can be quickly decomposed after use, reducing the impact on the environment; in addition, the composition for transfer prepared by this application, combined with the patterning process, the film material can play a role in applications with high precision requirements and has excellent compatibility, especially when combined with silver paste or silicon wafers in the preparation of electrode grid lines, it shows good stability.

[0031] A method for preparing an electrode grid line, comprising: Using the composition for transfer according to any one of claims 1 to 10, a polymer layer having a groove pattern is prepared, wherein the size and distribution of the groove pattern correspond to the size and distribution of the electrode grid lines; filling the groove pattern of the polymer layer with a conductive paste; Providing a silicon wafer, with the side coated with the conductive paste facing the silicon wafer, and covering the polymer layer on the silicon wafer; Performing hot pressing transfer to transfer the conductive paste onto the silicon wafer; The polymer layer is dissolved and removed by using an aqueous solution to obtain the electrode grid lines.

[0032] In a specific embodiment, making a polymer layer having grooves includes: providing a mold, the mold including protrusions corresponding to the electrode grid line pattern, coating the composition on the mold, using the mold to imprint a groove pattern on the composition, and curing the composition to obtain a polymer layer having a groove pattern.

[0033] By adopting the above technical solution, the composition used for transfer serves as an electrode grid line transfer carrier, which has the advantages of water-soluble and rapid film removal, simplifies the process, improves production efficiency, and meets environmental protection requirements, making this method have great application potential in the fields of microelectronics and flexible electronics; and during the transfer process, the composition used for transfer can maintain a stable structure and good surface quality, ensuring the integrity and fineness of the electrode grid line after transfer, and is particularly suitable for the transfer of fine structures.

[0034] In summary, the beneficial technical effects of this application are: 1. Optimize the solubility and mechanical properties of the film: By rationally controlling the molecular weight ratio of polyethylene glycol, the dissolution time and mechanical properties of the film are optimized, which can not only meet the needs of rapid film removal, but also ensure the strength and integrity of the film, thereby improving production efficiency and product quality; 2. Environmental friendliness and biodegradability: This solution uses water as a solvent, avoiding the use of organic solvents, significantly improving environmental friendliness and reducing harm to the environment and operators during production. Furthermore, all materials used are biodegradable, meeting the requirements of green production and sustainable development.

[0035] 3. Improve the flexibility and stability of the film: The use of plasticizers and film-forming aids enhances the flexibility and plasticity of the film, avoiding the film from breaking during the transfer process. Film-forming aids improve the surface smoothness and uniformity of the film, and enhance its mechanical strength and water resistance.

[0036] 4. Adjustable film properties: The ratio of low-molecular-weight and high-molecular-weight polyethylene glycols can precisely control the dissolution rate and mechanical properties of the film, thereby adapting to the needs of different production processes. In addition, the rational combination of surfactants, pore-forming agents, and cross-linking agents further improves the wettability, air permeability, anti-fouling ability, and thermal stability of the film. 5. Improve the transfer accuracy of electrode grid lines: In the preparation of electrode grid lines, the composition used for transfer can efficiently transfer the pattern, ensuring the integrity and fineness of the electrode grid lines after transfer. The groove pattern of the film accurately corresponds to the electrode grid line structure, ensuring the precise transfer of micron-level structures and avoiding defects or errors caused by mold mismatch; 6. Enhance the simplicity and efficiency of the production process: The film exhibits excellent water solubility during the transfer process of the electrode grid lines, which facilitates rapid film removal, simplifies the process flow, and improves production efficiency, making this technology particularly suitable for the fields of microelectronics and flexible electronics, and has great application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic flow chart of the preparation method of the composition used for transfer printing in the present application.

[0038] Figure 2 This is a flow chart of the electrode grid line preparation method in this application. DETAILED DESCRIPTION

[0039] The present application discloses a composition for transfer, which includes but is not limited to being used for the preparation of electrode grid lines. The composition for transfer can be used as a transfer carrier for the electrode grid lines. After the transfer is completed, the composition for transfer can be quickly removed by water dissolution. The composition for transfer printing comprises the following components in percentage by mass: Polyethylene glycol: 3-20%; as the core component of the film, polyethylene glycol has excellent water solubility and biocompatibility. Due to its stable chemical properties, polyethylene glycol does not undergo adverse chemical reactions with other materials such as conductive pastes or silicon wafers. Therefore, it can ensure the stability and compatibility of the film during use. The molecular weight and specific ratio of polyethylene glycol can be adjusted according to the application requirements of the film to achieve a balance between dissolution rate and mechanical properties; Plasticizer: 0.05-10%; the main function of the plasticizer is to improve the flexibility and plasticity of the film, making the film easier to handle during film formation; Film-forming aid: 1-15%; the addition of film-forming aid can effectively optimize the film-forming process and improve the surface smoothness and uniformity of the film; Surfactant: 0.01-2%; the main function of the surfactant is to change the hydrophilicity and lipophilicity of the film surface, thereby improving the film forming property, operability and surface wettability of the film; Pore-forming agent: 0.5-1%; the pore-forming agent can generate a microporous structure during the film formation process, so that the film has a certain air permeability or a controllable pore structure; Cross-linking agent: 0.01-1%; the main function of the cross-linking agent is to promote the cross-linking reaction between polyethylene glycol molecules; Release agent: 0.01-0.5%; Leveling agent: 0.01-0.5%; The balance is water; in this embodiment, the water is deionized water. Using water as a solvent improves the environmental friendliness of the film, reduces environmental pollution during the production process, and meets the requirements of green production and sustainable development; By rationally controlling the proportions of the above components, the dissolution rate of the composition for transfer printing in the present application is significantly optimized; it can dissolve rapidly in water while maintaining excellent strength and integrity, can meet the needs of rapid film removal, and ensure that after removal, it can still maintain its stability and functionality during the application process, thereby improving production efficiency and quality, not only meeting the requirements of rapid production, but also ensuring performance in high-intensity working environments.

[0040] In this embodiment, the polyethylene glycol includes low molecular weight polyethylene glycol and high molecular weight polyethylene glycol. The average molecular weight of the low molecular weight polyethylene glycol is 600-4000. The low molecular weight polyethylene glycol is mainly used to increase the dissolution rate of the film. Its smaller molecular weight allows it to dissolve more quickly in water. In applications requiring rapid film removal, the introduction of low molecular weight polyethylene glycol helps accelerate the dissolution process of the film, thereby improving production efficiency. In addition, the low molecular weight polyethylene glycol can also provide a certain degree of flexibility when forming the film, making the film easier to shape during operation. The average molecular weight of high molecular weight polyethylene glycol is 10,000-100,000; the introduction of high molecular weight polyethylene glycol helps to improve the mechanical strength, water resistance and stability of the film. Due to its large molecular weight, high molecular weight polyethylene glycol can enhance the cross-linking of polymer chains during the film formation process, improve the toughness and tensile strength of the film, and in addition, high molecular weight polyethylene glycol can also improve the surface smoothness of the film, prevent uneven surface defects in the film, and thus improve the overall quality of the film.

[0041] The mass ratio of low molecular weight polyethylene glycol to high molecular weight polyethylene glycol is 1: (0.1-10.0). In this embodiment, preferably, the mass ratio of low molecular weight polyethylene glycol to high molecular weight polyethylene glycol is 2: 1. By reasonably adjusting the ratio of low molecular weight polyethylene glycol to high molecular weight polyethylene glycol, the solubility, mechanical strength and operability of the film can be precisely adjusted in different applications. For example, when the proportion of low molecular weight polyethylene glycol is higher, a faster film removal speed can be achieved. When the proportion of high molecular weight polyethylene glycol is higher, the strength and toughness of the film will be improved. By controlling the ratio of the two, the comprehensive performance of the film can be optimized according to actual needs, so that it can perform the best effect in different environments. By using this ratio design, the film can achieve a good balance between multiple properties, which not only meets the needs of rapid dissolution, but also ensures the mechanical strength and stability of the film, and has excellent comprehensive performance and wide application potential.

[0042] In this embodiment, the plasticizer includes one or more of a polyol and a polyol ether. In this embodiment, the polyol is preferably glycerol. Glycerol as a plasticizer can improve the flexibility of the film, so that the film has better mechanical properties and durability during application. It can also improve the chemical stability of the film, prevent the film from reacting with the conductive paste or the silicon wafer, avoid degradation of the film performance due to chemical reactions, and ensure that the film still maintains excellent physical and chemical properties under high temperature, high humidity and other environmental conditions. In this embodiment, the film-forming aid comprises, by weight percentage, 3-5% polyvinyl pyrrolidone (PVP). Adding 3-5% polyvinyl pyrrolidone to the film can improve the mechanical strength and adhesion of the film, and can enhance the surface smoothness and uniformity of the film, thereby improving the accuracy of the electrode grid lines during the transfer process. Polyvinyl alcohol (PVA): 0.5-5%; adding polyvinyl alcohol can further improve the water solubility and operability of the film, and can also increase the speed of the film's water dissolution process, making the film removal process more efficient and environmentally friendly; Carboxymethyl cellulose (CMC): 0.5-1%; adding carboxymethyl cellulose helps thicken the film, further improves the toughness and stability of the film, and supports the integrity and uniformity of the film structure; Gelatin: 0.5-1%; adding gelatin can enhance the flexibility of the film and improve the stability of the film layer. Gelatin is soluble in water, which increases the softness and adaptability of the film, making the film more suitable for transfer requirements on complex surfaces; Polyacrylamide (PAM): 0.1-1%; polyacrylamide can reduce melt viscosity, improve processing fluidity, and enhance film strength and toughness; Polypropylene glycol (PPG) or its derivatives, 0.1-1%; PPG has good compatibility with PEG and can provide internal lubrication during processing, improve fluidity, and enhance the flexibility and water solubility of the film; By adding glycerol and other film-forming aids, the film has high flexibility after formation, which can effectively adapt to the stress generated during the transfer process and avoid film breakage or deformation; it can also avoid chemical reactions between the film and the conductive paste or silicon wafer, reduce the performance degradation caused by chemical reactions, and ensure the chemical stability of the film; in the preparation of electrode grid lines, due to the addition of polyvinyl alcohol, carboxymethyl cellulose and other ingredients, after the film is transferred, it can be dissolved in water to remove the film. The film removal process is not only faster, but also completely dependent on water, avoiding the use of organic solvents and meeting environmental protection requirements. In this embodiment, the surfactant includes one or more of polyoxyethylene ethers, alkyl glycosides, fatty acid methyl ester sulfonates, soybean lecithin, and alkylolamides. The use of the above surfactants in the water-soluble PEG film can improve the solubility, disintegration, and uniformity of the film. By reducing the surface tension of the film and increasing the hydrophilicity of the film, the dissolution and disintegration process of the film in water is accelerated, and the surface smoothness and structural stability of the film are improved. In addition, these surfactants can improve the wettability of the film, so that the film exhibits better hydration and disintegration speed under different environmental conditions, especially in hard water or low temperature environments. The surfactant is preferably a polyoxyethylene ether, which includes polyoxyethylene sorbitan monooleate (Tween 80) and polyoxyethylene lauryl ether (Brij series). They have an amphiphilic structure, which can not only interact with PEG molecules but also reduce the friction between molecular chains, thereby playing an internal demolding role. They have good water solubility and will not have a negative impact on the solubility of the PEG film.

[0043] Pore-forming agents include one or more of ammonium bicarbonate, ammonium chloride, hydrogen peroxide, and azodicarbonamide. By using these pore-forming agents, a pore structure can be created in the film, significantly increasing the contact area between the membrane and water, thereby accelerating the rate at which water passes through the membrane. At the same time, the pore-forming agent can also promote the disintegration process of the membrane, effectively avoiding fouling and clogging problems of the membrane, and improving the overall performance and service life of the membrane. In this embodiment, the pore-forming agent is preferably ammonium bicarbonate. As a pore-forming agent, ammonium bicarbonate can decompose to produce carbon dioxide gas during the heat treatment of the film, thereby forming pores. The use of ammonium bicarbonate can achieve a more uniform and controllable pore structure while avoiding the complex chemical reactions that may be introduced by other pore-forming agents, thereby simplifying the production process.

[0044] The crosslinking agent includes one or more of glutaraldehyde, dopamine, and diamino compounds. By using the above-mentioned green crosslinking agents, the mechanical properties and durability of the membrane can be significantly enhanced, and the membrane's anti-fouling ability and thermal stability can be improved. At the same time, the green crosslinking agent has advantages in terms of environmental protection, meets the needs of sustainable development, and can improve the performance of membrane materials and reduce environmental impact. In this embodiment, the cross-linking agent is preferably dopamine. As a natural cross-linking agent, dopamine has a mild and uniform cross-linking effect, which can enhance the structural strength and durability of the film while maintaining the flexibility of the film. In addition, dopamine does not produce toxic by-products during the cross-linking process, meets green environmental protection requirements, and is suitable for high-standard film preparation.

[0045] In this embodiment, the release agent is an internal release agent, which includes one or more of polyethylene glycol derivatives, silane coupling agents, fatty acid salts, and composite emulsification systems; Polyethylene glycol derivatives such as PEG-200 and PEG-400 have inherent lubricity and can be directly added as internal release agents. They migrate to form a low-adhesion lubricating layer. They have excellent compatibility with the PEG matrix and can reduce the friction between molecular chains without affecting the water solubility of the film. Silane coupling agents such as aminosilane and epoxysilane act as auxiliary mold release components to enhance the separation effect of polyethylene glycol from the mold surface through chemical bonding, thereby reducing the amount of release agent used; Fatty acid salts such as calcium stearate and sodium stearate can form weak interactions with PEG molecules. When added at a level of 0.1-1%, they can promote internal migration and form an isolation layer without significantly affecting water solubility. Composite emulsification system: some formulas use a combination of paraffin wax, stearic acid, and vegetable oil (e.g., 5-20% paraffin wax + 5-8% stearic acid). This forms a stable dispersion system through an emulsification process, improving demoulding efficiency. The internal release agent of polyethylene glycol water-soluble film uses polyethylene glycol itself as the core ingredient, supplemented by silane coupling agents, fatty acid salts or composite emulsification systems. It achieves efficient demoulding through internal migration or chemical bonding, while taking into account water solubility and processing stability.

[0046] Leveling agents include one or more of silicone-modified leveling agents and non-silicone leveling agents; Silicone-modified leveling agents include, but are not limited to, polyether-modified organosiloxanes (e.g., DP-215, DP-210). They enhance wettability by reducing surface tension, improving film flatness and slip, and have good compatibility with the PEG matrix. Non-silicone leveling agents include, but are not limited to, fluorocarbon-modified polyacrylates (e.g., DP-260) and acrylate copolymers (e.g., DP-267). Fluorocarbon modified polyacrylate reduces surface tension without affecting recoatability and is suitable for PEG films with high transparency requirements. Acrylate copolymers can avoid subsequent coating adhesion problems that may be caused by silicone components and are suitable for scenarios with high requirements for interlayer bonding strength.

[0047] When selecting a leveling agent, the leveling agent must be compatible with the PEG solution to avoid precipitation or gelation; low-viscosity leveling agents are preferred; formulations containing silicones need to control the drying temperature to ≤60°C to prevent thermal degradation of PEG; in addition, water-based or solvent-free leveling agents (such as the DP series) are preferred to meet the requirements of pharmaceutical or food contact materials; by rationally selecting the leveling agent composition and addition amount, the yield and surface quality of PEG water-soluble films can be significantly improved.

[0048] Reference Figure 1 This embodiment provides a method for preparing a composition for transfer, which is used to prepare the above-mentioned composition for transfer. In this embodiment, the components and their proportions in the method for preparing the composition for transfer are as described above. The preparation method comprises the following steps: Disperse low molecular weight polyethylene glycol and high molecular weight polyethylene glycol in water at a mass ratio of 1: (0.1-10.0) and stir until completely dissolved; Add film-forming aid, surfactant and plasticizer in sequence and perform homogenization; Then add a crosslinking agent, a pore-forming agent, a release agent, and a leveling agent to carry out a crosslinking and foaming reaction, heat at 50-70°C for 5-15 minutes to ensure that the components in the solution are fully dissolved, and then dry at 40-60°C to obtain a composition for transfer.

[0049] The weight percentages of the components are as follows: polyethylene glycol: 3-20%; plasticizer: 0.05-10%; film-forming aid: 1-15%; surfactant: 0.01-2%; pore-forming agent: 0.5-1%; cross-linking agent: 0.01-1%; release agent: 0.01-0.5%; leveling agent: 0.01-0.5%; and the balance is water.

[0050] In this embodiment, preferably, the preparation method of the composition specifically includes: 1. Disperse high molecular weight polyethylene glycol and low molecular weight polyethylene glycol in water at a mass ratio of 1: (0.1-10.0) and stir until completely dissolved. In this embodiment, the water is deionized water. The average molecular weight of the low molecular weight polyethylene glycol is preferably 1000, which is mainly used to increase the dissolution rate of the film and promote the rapid dissolution of the film in water. The average molecular weight of the high molecular weight polyethylene glycol is preferably 50,000, which has good mechanical strength, water resistance and stability, and helps to improve the tensile strength and durability of the film. A reasonable ratio of the two can achieve a balance between the dissolution rate and strength of the film. During the dissolution process, high-speed stirring is used to ensure that the polyethylene glycol is completely dissolved to avoid the presence of particles or undissolved substances.

[0051] 2. Add polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, gelatin, Tween 80, and glycerol in sequence. After all ingredients are mixed evenly, homogenize them to ensure the uniformity and stability of the solution, laying the foundation for the subsequent film-forming process.

[0052] 3. Add dopamine, ammonium bicarbonate, polyethylene glycol derivative, and polyether-modified organosiloxane, heat at 60°C for 10 minutes to ensure that the components in the solution are fully dissolved, and then dry at 50°C to obtain a composition for transfer.

[0053] In this embodiment, the obtained composition for transfer has good water solubility, and the pH value is controlled in the neutral range (6.5-7.5), ensuring that it has ideal physical and chemical properties in various use environments.

[0054] The technical effects of this embodiment include: Co-designed formulation: Low molecular weight polyethylene glycol (PEG) provides high solubility and a faster dissolution rate, optimizing the film's dissolution behavior in water. The addition of carboxymethyl cellulose (CMC) helps enhance the film's mechanical properties and improve its stability in water. CMC can form a cross-linked structure in water, improving the film's strength and durability. Polyvinylpyrrolidone (PVP), as a hydrophilic material, contributes to the film's water solubility and stability in a humid environment, further balancing the film's dissolution rate and mechanical properties to ensure controllability and durability. The synergistic effect of these ingredients can improve the film's dissolution rate while maintaining good mechanical properties, resulting in a film with high reliability and applicability in practical applications. Environmental compatibility: The ingredients used in this application are all biodegradable and meet environmental requirements, allowing the film to quickly decompose after use, reducing the impact on the environment. The composition used for transfer printing has a neutral pH (6.5-7.5) to avoid reaction with conductive paste or silicon wafers. Reference Figure 2This embodiment also provides a method for preparing an electrode grid line, using the above-mentioned transfer composition as a transfer carrier; 1. Providing a mold, the mold including protrusions corresponding to the electrode grid line pattern, and using the above-mentioned composition for transfer to produce a polymer layer having a groove pattern, wherein the size and distribution of the groove pattern correspond to the size and distribution of the electrode grid lines; The method of preparing the polymer layer having the groove pattern specifically includes: coating the composition on a mold, imprinting the groove pattern on the composition using the mold, and curing the composition to obtain the polymer layer having the groove pattern; In this embodiment, the groove pattern is formed by mold imprinting or laser etching, and the groove pattern has a width of 4-10 μm, a depth of 10-25 μm, and an aspect ratio of >1; 2. Filling the groove pattern of the polymer layer with conductive paste; 3. Provide a silicon wafer, with the side coated with the conductive paste facing the silicon wafer, and cover the silicon wafer with a polymer layer; 4. Perform hot pressing transfer, maintaining the temperature of 80-200°C and the pressure of 1-20 MPa for 0.1-10 minutes to firmly transfer the conductive paste to the silicon wafer; 5. Place the transferred silicon wafer in room temperature water to completely dissolve the transfer composition, leaving the electrode grid lines; 6. Place the silicon wafer with the electrode grid lines into a heating furnace and solidify and sinter it under appropriate temperature and air environment to make the conductive paste form electrode grid lines with good conductivity and stability. Specific embodiments Some specific implementation methods will be further introduced below to further explain the technical solution of this application in detail.

[0056] Example 1 Preparation method: High molecular weight polyethylene glycol and low molecular weight polyethylene glycol are dispersed in water and stirred until completely dissolved; polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, gelatin, Tween 80, and glycerol are added in sequence, all ingredients are mixed evenly, and then homogenized to ensure the uniformity and stability of the solution, laying the foundation for the subsequent film-forming process; dopamine and ammonium bicarbonate, polyethylene glycol derivatives, and polyether-modified organosiloxane are then added, heated at 60°C for 10 minutes to ensure that the ingredients in the solution are fully dissolved, and then dried at 50°C to form a film of uniform thickness to obtain a composition for transfer printing; The polymer layer having the groove pattern is prepared using the transfer composition. Specifically, the composition is coated on a mold, the groove pattern is embossed on the composition using the mold, and the composition is cured to obtain the polymer layer having the groove pattern.

[0057] Example 2 The difference from Example 1 is that the mass percentage of high molecular weight polyethylene glycol is changed from 4% to 8%; the other components are the same as those in Example 1, and the other method steps are the same as those in Example 1 Example 3 The difference from Example 1 is that the mass percentages of high molecular weight polyethylene glycol and low molecular weight polyethylene glycol are 2.5% and 2.5% respectively; the remaining components are the same as those in Example 1, and the remaining method steps are the same as those in Example 1.

[0058] Example 4 The difference from Example 1 is that the glycerol content is 0.5%; the remaining components are the same as those in Example 1, and the remaining method steps are the same as those in Example 1.

[0059] Comparative Example 1 Preparation method: Add 15% PVA1788 to water and stir and dissolve at 90°C for 1 hour to form a polyvinyl alcohol solution; After the polyvinyl alcohol solution was cooled to 65°C, glycerol was added and stirred for 0.5 hours to obtain a mixed solution; The mixed solution was poured into a mold with a pattern and cast to form a film at a casting speed of 8 cm / min. The mold with the film was placed in a drying oven and dried at 85°C for 5 minutes to obtain a traditional PVA film.

[0060] Related test descriptions: 1. Dissolution performance test: Place the prepared membrane sample (30 micron thick) in deionized water at 25°C. Start timing and record the time it takes for the membrane sample to completely dissolve from the moment it contacts the water surface. This test evaluates the dissolution efficiency of the membrane material and verifies the dissolution rate.

[0061] 2. Mechanical properties testing: The membrane samples are tested for tensile strength and elongation at break using a universal material testing machine. During the test, the membrane sample is clamped in the testing machine's fixture and stretched at a constant speed until the membrane breaks. By recording the maximum force during stretching and the elongation at break, the tensile strength and elongation of the membrane sample can be calculated. This assesses the mechanical stability of the membrane material and ensures its shape retention during subsequent processing.

[0062] 3. Silver paste transfer accuracy test. During the silver paste transfer test, silver paste is first filled into the grooves of the film sample. The film sample with silver paste is then transferred to the silicon wafer surface. Subsequently, the film layer is dissolved to release the silver paste, and then sintered and solidified at high temperature to ensure a close bond between the silver paste and the silicon wafer. Finally, the width and resistivity of the gate lines are measured using precision measurement tools to evaluate the transfer accuracy and the bonding quality of the silver paste to the silicon wafer.

[0063] Please refer to the table below for specific test results. The advantages of the transfer composition of the present application compared with traditional PVA films are as follows: 1. Solubility performance advantage Rapid disintegration mechanism: The composition for transfer printing of the present application generates CO2 bubbles through the decomposition of bicarbonate, forming microporous channels and accelerating the disintegration of the film layer.

[0064] Wide pH adaptability: The composition used for transfer has stable solubility in the pH range of 5-9, while PVA film is prone to cross-linking at high pH, resulting in decreased solubility.

[0065] 2. Environmental protection and biocompatibility Boric acid-free cross-linking: Dopamine is used as a green cross-linking agent to avoid the potential corrosion of silver paste glass powder by boric acid in traditional PVA film.

[0066] Bio-based alternatives: Support bio-based polyethylene glycol (such as corn sugar sources) to reduce carbon footprint.

[0067] 3. Compatibility with photovoltaic processes Groove shape retention: The composition used for transfer has a synergistic effect of gelatin and carboxymethyl cellulose, and the groove deformation rate of the film under transfer pressure (0.1-0.5MPa) is less than 0.5%.

[0068] Compatible with low-temperature sintering: After the transfer composition is dissolved, there is no need for high-temperature cleaning. The silver paste can be directly sintered at low temperatures (200-300°C), reducing thermal stress damage to the silicon wafer.

[0069] 4. Economic efficiency and industrialization potential Continuous production: The transfer composition can be produced roll-to-roll through an extrusion coating process, increasing efficiency by 50%.

[0070] Recycling and reuse: The dissolved composition solution used for transfer can be concentrated and reused to reduce the waste of raw materials.

[0071] The transfer composition of the present application is significantly superior to traditional PVA films in terms of dissolution rate, mechanical properties, environmental friendliness, process compatibility, and economy. Specific advantages include: Disruptive dissolution mechanism: micropore disintegration + low molecular chain synergy, achieving rapid dissolution in 50 seconds; Green process chain: pollution-free from raw materials (bio-based polyethylene glycol) to waste liquid treatment; High-precision transfer: The groove structure stability and low-temperature compatibility meet the needs of the new generation of high-efficiency photovoltaic cells; Industrialization cost advantage: reduction in both raw material and energy consumption, promoting photovoltaic process upgrades; The composition for transfer in this application achieves rapid dissolution of the water-soluble film, high mechanical properties, environmental compatibility and high-precision transfer through innovative formula and structural design, solving key problems in the preparation of photovoltaic cell electrode grid lines, and has significant technical advantages and application value; this technical solution has clear technical substitutability and market application potential in the photovoltaic field.

[0072] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A composition for transfer printing, characterized in that: Calculated by mass percentage, it includes the following components: Polyethylene glycol: 3-20%; Plasticizer: 0.05-10%; Film-forming aid: 1-15%; surfactant: 0.01-2%; Pore forming agent: 0.5-1%; Cross-linking agent: 0.01-1%; Release agent: 0.01-0.5%; Leveling agent: 0.01-0.5%; the balance is water.

2. The composition for transfer according to claim 1, characterized in that: The polyethylene glycol includes low molecular weight polyethylene glycol and high molecular weight polyethylene glycol, and the mass ratio of the high molecular weight polyethylene glycol to the low molecular weight polyethylene glycol is 1:(0.1-10.0).

3. The composition for transfer according to claim 2, characterized in that: The average molecular weight of the low molecular weight polyethylene glycol is 600-4000, and the average molecular weight of the high molecular weight polyethylene glycol is 10000-100000.

4. The composition for transfer according to claim 1, characterized in that: The plasticizer includes one or more of polyols and polyol ethers.

5. The composition for transfer according to claim 1, characterized in that: The film-forming aid includes one or more of polyvinyl pyrrolidone, polyvinyl alcohol, carboxymethyl cellulose, gelatin, polyacrylamide, and polypropylene glycol.

6. The composition for transfer printing according to claim 1, wherein: The surfactant includes one or more of polyoxyethylene ethers, alkyl glycosides, fatty acid methyl ester sulfonates, soybean lecithin and alkyl alcohol amides.

7. The composition for transfer printing according to claim 1, wherein: The pore-forming agent is one or more of ammonium bicarbonate, ammonium chloride, hydrogen peroxide, and azodicarbonamide.

8. The composition for transfer printing according to claim 1, wherein: The cross-linking agent is one or more of glutaraldehyde, dopamine, and diamino compounds.

9. The composition for transfer printing according to claim 1, wherein: The release agent includes one or more of polyethylene glycol derivatives, silane coupling agents, fatty acid salts, and composite emulsification systems.

10. The composition for transfer printing according to claim 1, characterized in that: The leveling agent includes one or more of an organosilicon-modified leveling agent and a non-silicone leveling agent.

11. A method for preparing the composition for transfer according to any one of claims 1 to 10, characterized in that: include: Disperse polyethylene glycol in water and stir until completely dissolved; Add film-forming aid, surfactant and plasticizer in sequence and perform homogenization; Then add a crosslinking agent, a pore-forming agent, a release agent, and a leveling agent to carry out a crosslinking foaming reaction, heat at 50-70°C for 5-15 minutes to ensure that the components in the solution are fully dissolved, and then dry at 40-60°C to obtain a composition for transfer. The weight percentages of the components are as follows: polyethylene glycol: 3-20%; plasticizer: 0.05-10%; film-forming aid: 1-15%; surfactant: 0.01-2%; pore-forming agent: 0.5-1%; cross-linking agent: 0.01-1%; release agent: 0.01-0.5%; leveling agent: 0.01-0.5%; and the balance is water.

12. A method for preparing an electrode grid line, characterized in that: include: Using the transfer composition according to any one of claims 1 to 10, a polymer layer having a groove pattern is prepared, wherein the size and distribution of the groove pattern correspond to the size and distribution of the electrode grid lines; filling the groove pattern of the polymer layer with a conductive paste; Providing a silicon wafer, with the side coated with the conductive paste facing the silicon wafer, and covering the polymer layer on the silicon wafer; Performing hot pressing transfer to transfer the conductive paste onto the silicon wafer; The polymer layer is dissolved and removed by using an aqueous solution to obtain the electrode grid lines.

13. The method for preparing an electrode grid line according to claim 12, wherein: The preparation of a polymer layer with grooves includes: providing a mold, the mold including protrusions corresponding to the electrode grid line pattern, coating the composition on the mold, using the mold to imprint a groove pattern on the composition, and curing the composition to obtain a polymer layer with a groove pattern.

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