A method of reducing silver paste resistance in electrochromic glass

Abstract

The application provides a curing method for reducing the resistance of silver paste in electrochromic glass, and the curing method comprises the following steps: electrochromic glass coated with silver paste is sequentially subjected to preheating treatment, heating treatment, constant temperature curing, temperature decreasing treatment and cooling treatment to complete curing; the preheating treatment, the heating treatment, the constant temperature curing and the temperature decreasing treatment are all carried out in a flow line tunnel furnace. Through stage-by-stage heating and independent temperature control in each stage, the silver paste is completely cured, the resistance of the silver paste after curing is low, the conductivity of the silver paste is improved, the adhesion between the silver paste and the electrochromic glass is effectively improved, and the service life of the electrochromic glass is improved.

Description

Technical Field

[0001] This invention relates to the field of electrochromic materials technology, and in particular to a curing method for reducing the resistance of silver paste in electrochromic glass. Background Technology

[0002] In electrochromic glass, silver paste mainly serves to connect circuits within the film layer. Because the film layer is thin and the line width is only on the micrometer scale, the cross-section after the silver paste is filled is small. Therefore, it is necessary to ensure that this part of the silver paste is fully cured to improve conductivity and reduce resistance.

[0003] The existing technology uses high-temperature heating in an oven / tunnel furnace for curing. Due to the different silver paste materials, the curing temperature is also different. The mismatch of curing processes will cause the silver paste mixed solvent to evaporate rapidly, destroying the silver ion combination, and the cured silver paste will have a high resistance.

[0004] CN120097641A discloses a method for curing conductive silver paste and a method for preparing electrochromic glass. The curing method includes: contact heating the other side of the device substrate coated with conductive silver paste relative to the conductive silver paste. The contact heating process includes heating at a first temperature and then heating at a second temperature, wherein the first temperature is lower than the second temperature. After the contact heating is completed, the substrate is left to stand to complete the curing process.

[0005] CN114706250A discloses a high-transmittance aerogel composite electrochromic glass and its preparation method, comprising a first substrate, a PVB casting film layer, a second substrate and an aerogel filling layer arranged sequentially. The first substrate comprises a first substrate, a first antireflective dielectric film layer, a barrier layer, a conductive layer, a first transparent conductive layer and a cathodic color-changing layer arranged sequentially. The second substrate comprises a second substrate, a second antireflective dielectric film layer, a second transparent conductive film layer and an anodic color-changing layer arranged sequentially.

[0006] CN111650795A discloses an electrochromic glass, comprising a substrate, the substrate including a first substrate and a second substrate, an electrochromic device being included between the first substrate and the second substrate, the electrochromic device being sequentially disposed from the first substrate with a first conductive layer, an electrochromic layer, an ion conducting layer, an ion storage layer, and a second conductive layer; an electrode being configured to supply power to the electrochromic device; the inner surface of the substrate including a groove, the groove being positioned opposite to the electrode, the depth of the groove being less than the thickness of the substrate, and the outer periphery of the groove and the periphery of the substrate being sealed by an edge sealing material.

[0007] However, the aforementioned electrochromic glass still has problems such as high resistance of the cured silver paste and weak adhesion between the cured silver paste and the electrochromic glass. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a curing method for reducing the resistance of silver paste in electrochromic glass. The electrochromic glass coated with silver paste is subjected to preheating treatment, heating treatment, constant temperature curing, cooling treatment and cooling treatment in sequence to fully cure the silver paste, effectively reduce the resistance of silver paste, improve the adhesion between silver paste and electrochromic glass, and thus improve the service life of electrochromic glass, which is suitable for widespread application.

[0009] To achieve this objective, the present invention adopts the following technical solution: This invention provides a curing method for reducing the resistance of silver paste in electrochromic glass, the curing method comprising the following steps: Electrochromic glass coated with silver paste undergoes a series of processes, including preheating, heating, constant temperature curing, cooling, and refrigeration, to complete the curing process. The preheating treatment, heating treatment, constant temperature curing and cooling treatment are all carried out in a continuous tunnel oven.

[0010] The curing method for reducing the resistance of silver paste in electrochromic glass described in this invention involves curing the silver paste coated on electrochromic glass in a tunnel furnace on a production line. First, a preheating treatment is performed to evaporate the solvent in the silver paste, allowing the silver ions in the paste to initially bind. This avoids directly heating to the heating treatment temperature, which could cause a large temperature difference and breakage of the electrochromic glass, and also avoids rapid evaporation of the solvent in the silver paste, which could damage the silver ion binding and result in high silver paste resistance. Next, a heating treatment and isothermal curing are performed to fully cure the silver paste. Then, a cooling treatment is performed to prevent excessive temperature differences from causing breakage of the electrochromic glass. Finally, a cooling treatment is performed to cool to room temperature. The curing method of this invention uses staged heating, with independent temperature control at each stage, to ensure complete curing of the silver paste, achieving lower resistance. The conductivity of the cured silver paste is improved, and the adhesion between the silver paste and the electrochromic glass is effectively enhanced, thus increasing the service life of the electrochromic glass.

[0011] The cooling process described in this invention is carried out outside the automated tunnel furnace.

[0012] Preferably, the silver paste comprises 80-95 wt% silver powder, for example, 80 wt%, 83 wt%, 86 wt%, 89 wt%, 92 wt%, or 95 wt%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0013] The resin content is 4 to 10 wt%, for example, it can be 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt% or 10 wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] The curing agent is 0.5~3wt%, for example, it can be 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt% or 3.0wt%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] The solvent is 0.5~3wt%, for example, it can be 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt% or 3.0wt%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] Preferably, the resin comprises any one or a combination of at least two of epoxy resin, polyimide resin, polyurethane resin or acrylic resin, wherein typical but not limited combinations include a combination of epoxy resin and polyimide resin, a combination of polyurethane resin and acrylic resin or a combination of epoxy resin and polyurethane resin.

[0017] Preferably, the curing agent comprises any one or a combination of at least two of isocyanate curing agents, amine curing agents, or imidazole curing agents, wherein typical but non-limiting combinations include a combination of isocyanate curing agents and amine curing agents, a combination of imidazole curing agents and isocyanate curing agents, or a combination of amine curing agents and imidazole curing agents.

[0018] For example, the isocyanate curing agent includes a blocked isocyanate.

[0019] For example, the amine curing agent includes dicyandiamide.

[0020] For example, the imidazole curing agent includes 2-methylimidazole.

[0021] The solvents described in this invention are conventional reagents in the art, and those skilled in the art can select the solvent type according to actual needs.

[0022] For example, the solvent includes at least one of acetone, ethyl acetate, isopropanol, or dimethylformamide.

[0023] Preferably, the preheating treatment is carried out in a preheating cavity.

[0024] Preferably, the heat treatment is performed in a heating chamber.

[0025] Preferably, the isothermal curing is carried out in an isothermal cavity.

[0026] Preferably, the number of constant temperature cavities is 1 to 2, for example, 1 or 2.

[0027] Preferably, the number of constant temperature chambers in this invention is 1 to 2 to ensure sufficient curing of the silver paste. Using too many constant temperature chambers will increase the processing time of the entire curing process and reduce the curing effect of the silver paste.

[0028] Preferably, the cooling process is performed in a cooling cavity.

[0029] The preheating treatment, heating treatment, constant temperature curing and cooling treatment described in this invention are carried out in different cavities, and the temperature in each cavity is independently controlled, thereby making the silver paste more fully cured.

[0030] Preferably, the electrochromic glass coated with silver paste is conveyed by a conveyor belt through a preheating chamber, a heating chamber, a constant temperature chamber, and a cooling chamber in sequence. The time of the electrochromic glass in different processing stages can be controlled by adjusting the speed of the conveyor belt.

[0031] Preferably, the temperature of the preheating treatment is 80~130℃, for example, it can be 80℃, 90℃, 100℃, 110℃, 120℃ or 130℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] The preferred temperature for the preheating treatment in this invention is 80~130℃, which allows the solvent in the silver paste to fully evaporate and promotes the initial bonding of silver ions. If the preheating temperature is too low, the solvent in the silver paste will evaporate slowly, and abnormal appearances such as bubbles and peeling will occur in the high-temperature zone; if the preheating temperature is too high, the electrochromic glass will heat up too quickly and unevenly, resulting in breakage.

[0033] Preferably, the preheating time is 5 to 8 minutes, for example, 5 minutes, 5.5 minutes, 6 minutes, 7 minutes, 7.5 minutes or 8 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] Preferably, the temperature of the heat treatment is 160~190℃, for example, it can be 160℃, 165℃, 170℃, 175℃, 180℃ or 190℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] The preferred temperature for the heat treatment in this invention is 160~190℃ to ensure the silver paste is fully cured. Lower heat treatment temperatures result in poorer curing of the silver paste, leading to higher resistance after curing. Higher heat treatment temperatures cause a greater difference in internal stress between the electrochromic glass and the silver paste, resulting in silver paste detachment, performance failure, and increased equipment energy consumption.

[0036] Preferably, the heating treatment time is 5 to 8 minutes, for example, 5 minutes, 5.5 minutes, 6 minutes, 7 minutes, 7.5 minutes or 8 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the temperature for constant temperature curing is 160~190℃, for example, it can be 160℃, 165℃, 170℃, 175℃, 180℃ or 190℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the isothermal curing time is 5 to 8 minutes, for example, 5 minutes, 5.5 minutes, 6 minutes, 7 minutes, 7.5 minutes or 8 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the temperature of the cooling treatment is 70~80℃, for example, it can be 70℃, 72℃, 74℃, 76℃, 78℃ or 80℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, the cooling process takes 5 to 8 minutes, for example, 5 minutes, 5.5 minutes, 6 minutes, 7 minutes, 7.5 minutes or 8 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] Preferably, the cooling temperature is 20~30℃, for example, it can be 20℃, 22℃, 24℃, 26℃, 28℃ or 30℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the cooling time is 5 to 8 minutes, for example, 5 minutes, 5.5 minutes, 6 minutes, 7 minutes, 7.5 minutes or 8 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the resistance of the cured silver paste is 0.05~0.1Ω / m, for example, it can be 0.05Ω / m, 0.06Ω / m, 0.07Ω / m, 0.08Ω / m, 0.09Ω / m or 0.10Ω / m, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the adhesion between the cured silver paste and the electrochromic glass is >40N, for example, it can be 41N, 43N, 45N, 47N, 49N or 50N, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] As a preferred technical solution of the present invention, the curing method includes the following steps: Electrochromic glass coated with silver paste is conveyed by a conveyor belt through a preheating chamber, a heating chamber, a constant temperature chamber, and a cooling chamber. It undergoes a series of treatments: preheating at 80-130℃ for 5-8 minutes, heating at 160-190℃ for 5-8 minutes, constant temperature curing at 160-190℃ for 5-8 minutes, cooling at 70-80℃ for 5-8 minutes, and cooling at 20-30℃ for 5-8 minutes, completing the curing process. The resistivity of the cured silver paste is 0.05-0.1 Ω / m; the adhesion between the cured silver paste and the electrochromic glass is >40 N. The preheating treatment, heating treatment, constant temperature curing and cooling treatment are all carried out in a tunnel furnace on an assembly line; the silver paste includes: 80~95wt% silver powder, 4~10wt% resin, 0.5~3wt% curing agent and 0.5~3wt% solvent; the number of constant temperature chambers is 1~2.

[0046] Compared with the prior art, the present invention has at least the following beneficial effects: The curing method for reducing the resistance of silver paste in electrochromic glass provided by this invention involves a staged process with independent temperature control at each stage, which allows the silver paste to be completely cured. The resistance of the cured silver paste is 0.05~0.1Ω / m, and the adhesion between the cured silver paste and the electrochromic glass is >40N, which significantly improves the service life of the electrochromic glass. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the apparatus used in the curing method for reducing the resistance of silver paste in electrochromic glass in Embodiment 1 of the present invention.

[0048] In the diagram: 1-Preheating chamber; 2-Heating chamber; 3-First constant temperature chamber; 4-Second constant temperature chamber; 5-Cooling chamber; 6-Conveyor belt. Detailed Implementation

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0050] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0051] Example 1 This embodiment provides a curing method for reducing the resistance of silver paste in electrochromic glass. The curing method includes the following steps: A schematic diagram of the apparatus used in the curing method is shown below. Figure 1 As shown. Figure 1 The thick blue arrow indicates the direction of the conveyor belt.

[0052] In this embodiment, there are two constant temperature cavities, which are named the first constant temperature cavity 3 and the second constant temperature cavity 4, respectively.

[0053] Electrochromic glass coated with silver paste is conveyed by conveyor belt 6 through preheating chamber 1, heating chamber 2, constant temperature chamber and cooling chamber 5 in sequence. It undergoes preheating treatment at 130℃ for 7 minutes, heating treatment at 180℃ for 7 minutes, constant temperature curing at 180℃ for 7 minutes, cooling treatment at 80℃ for 7 minutes and cooling treatment at 30℃ for 7 minutes to complete the curing. The silver paste comprises: 85wt% silver powder, 10wt% epoxy resin, 3wt% dicyandiamide, and 2wt% ethyl acetate; the preheating treatment, heating treatment, constant temperature curing, and cooling treatment are all carried out in a continuous tunnel furnace.

[0054] Example 2 This embodiment provides a curing method for reducing the resistance of silver paste in electrochromic glass, the curing method comprising the following steps: Electrochromic glass coated with silver paste is conveyed by a conveyor belt through a preheating chamber, a heating chamber, a constant temperature chamber, and a cooling chamber. It undergoes a preheating treatment at 80°C for 5 minutes, a heating treatment at 180°C for 5 minutes, a constant temperature curing treatment at 190°C for 5 minutes, a cooling treatment at 70°C for 8 minutes, and a cooling treatment at 20°C for 8 minutes to complete the curing process. The silver paste comprises: 95wt% silver powder, 4wt% acrylic resin, 0.5wt% 2-methylimidazole, and 0.5wt% dimethylformamide; the preheating treatment, heating treatment, constant temperature curing, and cooling treatment are all carried out in a continuous tunnel oven.

[0055] Example 3 This embodiment provides a curing method for reducing the resistance of silver paste in electrochromic glass, the curing method comprising the following steps: Electrochromic glass coated with silver paste is conveyed by a conveyor belt through a preheating chamber, a heating chamber, a constant temperature chamber, and a cooling chamber. It undergoes a preheating treatment at 100°C for 8 minutes, a heating treatment at 160°C for 8 minutes, a constant temperature curing treatment at 160°C for 8 minutes, a cooling treatment at 80°C for 5 minutes, and a cooling treatment at 30°C for 5 minutes to complete the curing process. The silver paste comprises: 90 wt% silver powder, 4 wt% polyurethane resin, 3 wt% dicyandiamide, and 3 wt% acetone; the preheating treatment, heating treatment, constant temperature curing, and cooling treatment are all carried out in a continuous tunnel furnace.

[0056] Based on embodiments 1-3, the curing method for reducing the resistance of silver paste in electrochromic glass provided by the present invention is reasonably designed. Through staged processing and independent temperature control of each stage, the silver paste is completely cured, and the resistance of the cured silver paste is 0.05~0.1Ω / m; the adhesion between the cured silver paste and the electrochromic glass is >40N.

[0057] Example 4 This embodiment provides a curing method for reducing the resistance of silver paste in electrochromic glass. The curing method is the same as in Embodiment 1, except that the preheating temperature is 70°C.

[0058] Example 5 This embodiment provides a curing method for reducing the resistance of silver paste in electrochromic glass. The curing method is the same as in Embodiment 1, except that the preheating temperature is 140°C.

[0059] Combining Examples 1 and 4-6, the preheating temperature in Example 4 is relatively low, which leads to slower solvent evaporation in the silver paste and causes abnormal appearances such as bubbles and peeling in the high-temperature zone; the preheating temperature in Example 5 is relatively high, which leads to the electrochromic glass heating up too quickly and uneven heating, resulting in breakage.

[0060] Example 6 This embodiment provides a curing method for reducing the resistance of silver paste in electrochromic glass. The curing method is the same as in Embodiment 1, except that the heating temperature is 150°C.

[0061] Example 7 This embodiment provides a curing method for reducing the resistance of silver paste in electrochromic glass. The curing method is the same as in Embodiment 1, except that the heating temperature is 200°C.

[0062] Combining Examples 1 and 6-7, the lower heating temperature in Example 6 leads to a poorer curing effect of the silver paste, resulting in higher resistance of the cured silver paste. The higher heating temperature in Example 7 leads to a greater difference in internal stress between the electrochromic glass and the silver paste, causing the silver paste to fall off, resulting in performance failure and increased energy consumption of the equipment.

[0063] Comparative Example 1 This comparative example provides a curing method for reducing the resistance of silver paste in electrochromic glass. The curing method is the same as in Example 1, except that preheating treatment is not performed and the heating treatment time is extended to 14 minutes.

[0064] This comparative example does not undergo preheating treatment, and the heating treatment time is extended to 14 minutes. Directly heating to the heating treatment temperature will result in a large temperature difference, causing the electrochromic glass to break. In addition, the solvent in the silver paste evaporates rapidly, destroying the silver ion combination and resulting in high silver paste resistance.

[0065] Comparative Example 2 This comparative example provides a curing method for reducing the resistance of silver paste in electrochromic glass. The curing method is the same as in Example 1, except that constant temperature curing is not performed and the heat treatment time is extended to 14 minutes.

[0066] This comparative example did not undergo constant temperature curing, and the heating treatment time was extended to 14 minutes, which resulted in the silver paste not being fully cured, having a high resistance, and low adhesion between the silver paste and the electrochromic glass.

[0067] Comparative Example 3 This comparative example provides a curing method for reducing the resistance of silver paste in electrochromic glass. The curing method is the same as in Example 1, except that it does not perform a cooling treatment and is directly cooled after constant temperature curing.

[0068] This comparative example does not undergo cooling treatment. After constant temperature curing, it is directly cooled, which will cause the electrochromic glass to break due to excessive temperature difference. The adhesion between the silver paste and the electrochromic glass is also low.

[0069] It should be noted that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A curing method for reducing the resistance of silver paste in electrochromic glass, characterized in that, The curing method includes the following steps: Electrochromic glass coated with silver paste undergoes a series of processes, including preheating, heating, constant temperature curing, cooling, and refrigeration, to complete the curing process. The preheating treatment, heating treatment, constant temperature curing and cooling treatment are all carried out in a continuous tunnel oven.

2. The curing method according to claim 1, characterized in that, The silver paste comprises: 80-95 wt% silver powder, 4-10 wt% resin, 0.5-3 wt% curing agent, and 0.5-3 wt% solvent.

3. The curing method according to claim 1 or 2, characterized in that, The preheating process is carried out in a preheating chamber; Preferably, the heat treatment is performed in a heating chamber; Preferably, the isothermal curing is carried out in an isothermal cavity; Preferably, the number of the constant temperature chambers is 1 to 2; Preferably, the cooling process is performed in a cooling cavity.

4. The curing method according to any one of claims 1 to 3, characterized in that, The electrochromic glass with silver paste coated on its surface is conveyed by a conveyor belt through a preheating chamber, a heating chamber, a constant temperature chamber, and a cooling chamber in sequence.

5. The curing method according to any one of claims 1 to 4, characterized in that, The temperature of the preheating treatment is 80~130℃; Preferably, the preheating treatment time is 5-8 minutes.

6. The curing method according to any one of claims 1 to 5, characterized in that, The temperature of the heat treatment is 160~190℃; Preferably, the heat treatment time is 5 to 8 minutes.

7. The curing method according to any one of claims 1 to 6, characterized in that, The temperature for constant temperature curing is 160~190℃; Preferably, the isothermal curing time is 5-8 minutes.

8. The curing method according to any one of claims 1 to 7, characterized in that, The cooling process is performed at a temperature of 70~80℃; Preferably, the cooling process takes 5 to 8 minutes.

9. The curing method according to any one of claims 1 to 8, characterized in that, The cooling temperature is 20~30℃; Preferably, the cooling process takes 5 to 8 minutes.

10. The curing method according to any one of claims 1 to 9, characterized in that, The resistivity of the cured silver paste is 0.05~0.1Ω / m; Preferably, the adhesion between the cured silver paste and the electrochromic glass is >40N.

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