Curing method of conductive silver paste and preparation method of electrochromic glass

Abstract

The invention provides a curing method of conductive silver paste and a preparation method of electrochromic glass, the curing method comprises the following steps: a device substrate coated with the conductive silver paste is used for carrying out contact heating on the other surface, opposite to the conductive silver paste, of the device substrate, and the contact heating process comprises the following steps: firstly, heating at a first temperature, and then heating at a second temperature; and then heating is conducted at a second temperature, the first temperature is lower than the second temperature, standing is conducted after contact type heating is finished, and the curing process is completed. According to the curing method provided by the invention, the heating mode of conductive silver paste curing is optimized, the combination of anions in the silver paste is better, lower resistance can be achieved, the conductivity is improved, the adhesive force of the silver paste on a film layer can be improved, and the service life of a device is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochromic technology, and specifically relates to a method for curing a conductive silver paste and a method for preparing electrochromic glass. Background Art

[0002] Electrochromic glass is a material whose transparency or color can be controlled by applying voltage. It is widely used in the fields of architecture, automobiles, aerospace, etc., especially in energy saving and privacy protection. The working principle of this glass is based on the electrochromic effect, that is, when electric current passes through the electrochromic material in the glass, its optical properties (such as transparency and color) will change reversibly. Electrochromic glass is usually composed of multiple layers of thin films, which include electrochromic materials, conductive materials, electrolyte layers, etc.

[0003] In electrochromic glass, the conductive layer is one of the key parts. In order to achieve good electrical performance and stability, a layer of conductive silver paste is often coated on the surface of the glass. Silver paste is a conductive coating material composed of silver particles, solvents and other auxiliary components, with good conductivity, stability and low resistance. In electrochromic glass, silver paste is usually used to make the electrode layer, which plays the role of connecting the circuit so that the color-changing effect of the electrochromic layer can be effectively controlled when voltage is applied.

[0004] The curing process of silver paste is crucial to the performance of electrochromic glass. The purpose of silver paste curing is to stably combine the silver particles in the silver paste with other components to form a solid conductive film. The main components of silver paste are generally conductive silver powder, resin organic polymer bonding phase, and organic solvent. During curing, the organic solvent in the silver paste will evaporate and the volume will shrink. The resin organic polymer bonding phase will undergo a series of reactions to form a network structure, which serves as the basic skeleton of the conductive silver paste, ensuring that the conductive particles are stably suspended and bonded therein, thereby achieving the bonding of the conductive silver paste to the object to be bonded. The conductive particles are filled in the network structure, and the volume further shrinks. The conductive particles that were originally not in contact with each other are close together to form a conductive channel. During the curing process, the binding force between the silver particles is enhanced, the conductive performance is improved, and the mechanical strength and durability of the film layer are also improved.

[0005] CN115712218A discloses an electrochromic glass and its preparation method and application. During the preparation process, when preparing an electrode layer on a conductive layer, a conductive silver paste is added to a dispensing device for dispensing. After the dispensing is completed, a curing cabinet is used to heat and dry at 120-350°C to complete the curing of the conductive silver paste. In the preparation method of electrochromic glass of the existing technology, the commonly used method of curing the silver paste is high-temperature heating in an oven. This heating method is conducted from the outside of the silver paste to the inside, resulting in a temperature difference between the surface and the inside of the silver paste. In addition, direct high-temperature heating will cause the silver paste mixed solvent to evaporate rapidly, destroying the silver ion combination, resulting in high resistance and affecting the conductive effect.

[0006] Therefore, based on the problems existing in the existing curing methods, the present invention provides a curing method for conductive silver paste and a preparation method for electrochromic glass. Summary of the invention

[0007] The purpose of the present invention is to provide a method for curing a conductive silver paste and a method for preparing an electrochromic glass, optimize the curing mode of the conductive silver paste in the electrochromic glass, improve the electrical properties of the conductive silver paste, and further improve the performance of the electrochromic glass.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for curing a conductive silver paste, the curing method comprising:

[0010] The device substrate coated with conductive silver paste is contact-heated on the other side of the device substrate relative to the conductive silver paste. The contact heating process includes first 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 device substrate is allowed to stand to complete the curing process.

[0011] The curing method provided by the present invention heats from the other side relative to the conductive silver paste, and with the help of glass heat conduction, the conductive silver paste is first heated from the inside, so that the silver paste mixed solvent filled in the film layer is fully volatilized. At the same time, a two-stage heating curing method is adopted. First, heating is performed at a lower temperature lower than the curing temperature to initially combine the silver ions in the silver paste, and finally the silver paste is allowed to stand to quickly cure the silver paste on the surface of the silver paste film layer to complete the curing process. Compared with the existing high-temperature drying and curing, the anion combination in the silver paste is better, and lower resistance can be achieved, the conductive performance is reduced, and the adhesion of the silver paste on the film layer can be improved, thereby improving the service life.

[0012] Preferably, the first temperature is 50-120°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] In the present invention, during the curing process, the first stage of the curing process is first carried out at 50-120° C., which is slightly lower than the complete curing temperature of the silver paste, so that the silver paste is initially cured and the anions in the silver paste are initially combined. If the temperature is too low, the silver ions cannot achieve the initial combination effect, and the subsequent curing effect is poor, resulting in insufficient performance of the silver film layer; if the temperature is too high, the silver paste has been completely cured in this step, which is equivalent to only one step of curing, and the silver ion binding effect is not good, resulting in the same decrease in the performance of the silver film layer.

[0014] Preferably, the holding time of the first temperature is 10-40min, for example, it can be 10min, 15min, 20min, 25min, 30min, 35min or 40min, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. Preferably, the second temperature is 130-180°C, for example, it can be 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or 180°C, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0015] Preferably, the second temperature is 130-180°C, for example, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, the insulation time of the second temperature is 5-40 min, for example, it can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min or 40 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the standing temperature is 25-45°C, for example, it can be 25°C, 26°C, 28°C, 30°C, 32°C, 34°C, 35°C, 36°C, 38°C, 40°C, 42°C, 44°C or 45°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the standing time is 10-40 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min or 40 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the heating area of ​​the contact heating is larger than the coating area of ​​the conductive silver paste.

[0020] Preferably, the contact heating uses a platform heating device.

[0021] Preferably, the components of the conductive silver paste include: 80-95wt% silver powder, 4-10wt% resin, 0.5-3wt% curing agent, and 0.5-3wt% solvent.

[0022] In the conductive silver paste, the silver powder content is 80-95wt%, for example, it can be 80wt%, 82wt%, 84wt%, 85wt%, 86wt%, 88wt%, 90wt%, 92wt%, 94wt% or 95wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] In the conductive silver paste, the resin content is 4-10wt%, for example, it can be 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] In the conductive silver paste, the curing agent content is 0.5-3wt%, for example, it can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt% or 3wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In the conductive silver paste, the solvent content is 0.5-3wt%, for example, it can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt% or 3wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the resin includes any one of epoxy resin, polyimide resin, polyurethane resin or acrylic resin, or a combination of at least two of them.

[0027] Preferably, the curing agent includes any one of an isocyanate curing agent, an amine curing agent or an imidazole curing agent, or a combination of at least two of them.

[0028] Exemplarily, the isocyanate curing agent includes blocked isocyanate.

[0029] Exemplarily, the amine curing agent includes dicyandiamide.

[0030] Exemplarily, the imidazole curing agent includes 2-methylimidazole.

[0031] In the present invention, the solvent is a conventional reagent in the art, and those skilled in the art can select the type of solvent according to actual needs.

[0032] Exemplarily, the solvent includes at least one of acetone, ethyl acetate, isopropanol or dimethylformamide.

[0033] In a second aspect, the present invention provides a method for preparing electrochromic glass, the preparation method comprising: coating a conductive silver paste on a device substrate on which an electrochromic glass functional layer is prepared, curing it using the curing method described in the first aspect, and completing packaging to obtain the electrochromic glass.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The curing method provided by the present invention optimizes the heating mode of curing the conductive silver paste, and the anion combination in the silver paste is better, so that lower resistance can be achieved, the conductive performance is improved, and the adhesion of the silver paste on the film layer can be improved, thereby increasing the service life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of a curing method of a conductive silver paste provided in Example 1;

[0037] Among them: 1-glass substrate; 2-electrochromic functional film layer; 3-conductive silver paste; 4-platform heating equipment. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0039] In order to clearly illustrate the technical solution of the present invention, in a specific implementation, an electrochromic functional film layer is prepared on a glass substrate by a deposition method, laser scratching is performed on the electrochromic functional film layer to form grooves, and conductive silver paste is filled in the grooves to obtain an electrochromic glass substrate coated with conductive silver paste.

[0040] In order to clearly illustrate the technical solution of the present invention, in a specific implementation manner, the glass substrate is FTO glass (Shanghai Yaopi Glass), and the material of the electrochromic functional film layer is ITO.

[0041] Example 1

[0042] This embodiment provides a Figure 1 The curing method of the conductive silver paste is shown.

[0043] In this embodiment, the conductive silver paste comprises: 92 wt % of silver powder, 6 wt % of epoxy resin, 1 wt % of dicyandiamide curing agent, and 1 wt % of acetone solvent.

[0044] The epoxy resin is NPEL-128.

[0045] The curing method comprises the following steps:

[0046] (1) setting the temperature of the platform heating device to 80° C. and preheating for 30 minutes to make the temperature uniform, placing the electrochromic glass substrate coated with the conductive silver paste on the platform of the platform heating device, making the other side of the electrochromic glass substrate opposite to the conductive silver paste completely contact with the platform, and heating at 80° C. for 30 minutes to volatilize the silver paste solvent in the film layer;

[0047] (2) Then, the temperature of the platform heating device is set to 130° C., and the electrochromic glass substrate is heated for 10 minutes to allow the conductive silver paste to continue to solidify;

[0048] (3) After heating, the electrochromic glass substrate is left to stand at 30° C. for 30 minutes to allow the silver paste solvent to fully evaporate and complete the curing process.

[0049] Example 2

[0050] This embodiment provides a method for curing a conductive silver paste.

[0051] In this embodiment, the conductive silver paste comprises: 95 wt % of silver powder, 4 wt % of epoxy resin, 0.5 wt % of dicyandiamide curing agent, and 0.5 wt % of acetone solvent.

[0052] The epoxy resin is NPEL-128.

[0053] The curing method comprises the following steps:

[0054] (1) setting the temperature of the platform heating device to 50° C. and preheating for 30 minutes to make the temperature uniform, placing the electrochromic glass substrate coated with the conductive silver paste on the platform of the platform heating device, making the other side of the electrochromic glass substrate opposite to the conductive silver paste completely contact with the platform, and heating at 50° C. for 40 minutes to volatilize the silver paste solvent in the film layer;

[0055] (2) Then, the temperature of the platform heating device is set to 150° C., and the electrochromic glass substrate is heated for 40 minutes to allow the conductive silver paste to continue to solidify;

[0056] (3) After heating, the electrochromic glass substrate is left to stand at 25° C. for 40 minutes to allow the silver paste solvent to fully evaporate and complete the curing process.

[0057] Example 3

[0058] This embodiment provides a method for curing a conductive silver paste.

[0059] In this embodiment, the conductive silver paste comprises: 85 wt % of silver powder, 9 wt % of epoxy resin, 3 wt % of dicyandiamide curing agent, and 3 wt % of acetone solvent.

[0060] The epoxy resin is NPEL-128.

[0061] The curing method comprises the following steps:

[0062] (1) setting the temperature of the platform heating device to 120° C. and preheating for 30 minutes to make the temperature uniform, placing the electrochromic glass substrate coated with the conductive silver paste on the platform of the platform heating device, making the other side of the electrochromic glass substrate opposite to the conductive silver paste completely contact with the platform, and heating at 120° C. for 10 minutes to volatilize the silver paste solvent in the film layer;

[0063] (2) Then, the temperature of the platform heating device is set to 180° C., and the electrochromic glass substrate is heated for 5 minutes to allow the conductive silver paste to continue to solidify;

[0064] (3) After heating, the electrochromic glass substrate is left to stand at 45° C. for 10 minutes to allow the silver paste solvent to fully evaporate and complete the curing process.

[0065] Example 4

[0066] This embodiment provides a method for curing a conductive silver paste. Compared with Embodiment 1, the heating temperature of step (1) is set to 30° C., and the rest is the same as Embodiment 1.

[0067] Example 5

[0068] This embodiment provides a method for curing a conductive silver paste. Compared with Embodiment 1, the heating temperature of step (1) is set to 140° C., and the rest is the same as Embodiment 1.

[0069] Comparative Example 1

[0070] This comparative example provides a method for curing a conductive silver paste. Compared with Example 1, the heating temperature of step (1) is set to 130° C., that is, the electrochromic glass substrate is directly heated at 130° C. for 40 minutes. The rest is the same as Example 1.

[0071] Comparative Example 2

[0072] This comparative example provides a method for curing a conductive silver paste. Compared with Example 1, the step (3) of standing still is not performed, and the rest is the same as Example 1.

[0073] That is, the electrochromic glass substrate after the silver paste is cured is directly used for testing or packaging.

[0074] Comparative Example 3

[0075] This comparative example provides a method for curing a conductive silver paste, the curing method comprising:

[0076] The electrochromic glass substrate coated with the conductive silver paste was placed in an oven for drying at a temperature of 130° C. for 40 min to complete the curing process.

[0077] The resistance value of the silver paste was tested using a multimeter on the electrochromic glass substrate after the silver paste was cured in the embodiment and the comparative example, and the adhesion between the silver paste and the glass substrate was tested. The results are listed in Table 1.

[0078] The test method for the adhesion between the silver paste and the glass substrate is: welding a joint on the silver paste, using a tensile gauge to pull it, and obtaining the adhesion value.

[0079] Table 1

[0080]

[0081] As can be seen from Table 1, the silver paste curing method provided by the present invention can significantly improve the curing effect of the silver paste. After curing, the resistance value of the silver paste is significantly reduced, and the adhesion of the silver paste to the substrate is significantly improved, thereby improving the service life of the electrochromic device. Compared with Example 1, in Examples 4 and 5, when the first curing temperature is adjusted to be too high or too low, the resistance value and the adhesion effect of the silver paste are slightly reduced, which may be caused by the poor silver ion binding effect. In Comparative Example 1, the substrate is directly heated to a higher temperature for a single curing, lacking the gradual volatilization of the solvent, and the gradual combination of silver ions. The curing speed is too fast, resulting in a significant deterioration in the effect; in Comparative Example 2, no standing is performed, the solvent volatilization effect is not good, and the silver paste curing is poor; in Comparative Example 3, the drying method is adopted, which will cause the surface of the film layer to cure faster, the internal heating is uneven, the silver ion binding effect is not good, and at the same time, the solvent is also difficult to volatilize outward, and the final silver film layer effect is significantly deteriorated.

[0082] In summary, the curing method provided by the present invention optimizes the heating method for curing the conductive silver paste, and the anion combination in the silver paste is better, which can achieve lower resistance, reduce the conductivity, and improve the adhesion of the silver paste on the film layer, thereby improving the service life.

[0083] The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for curing a conductive silver paste, characterized in that: The curing method comprises: The device substrate coated with conductive silver paste is contact-heated on the other side of the device substrate relative to the conductive silver paste. The contact heating process includes first 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 device substrate is allowed to stand to complete the curing process.

2. The curing method according to claim 1, characterized in that: The first temperature is 50-120°C.

3. The curing method according to claim 1 or 2, characterized in that: The insulation time at the first temperature is 10-40 minutes.

4. The curing method according to any one of claims 1 to 3, characterized in that: The second temperature is 130-180°C.

5. The curing method according to any one of claims 1 to 4, characterized in that: The second temperature holding time is 5-40 minutes.

6. The curing method according to any one of claims 1 to 5, characterized in that: The standing temperature is 25-45°C.

7. The curing method according to any one of claims 1 to 6, characterized in that: The standing time is 10-40 min.

8. The curing method according to any one of claims 1 to 7, characterized in that: The heating area of ​​the contact heating is larger than the coating area of ​​the conductive silver paste; Preferably, the contact heating uses a platform heating device.

9. The curing method according to any one of claims 1 to 8, characterized in that: The components of the conductive silver paste include: 80-95wt% of silver powder, 4-10wt% of resin, 0.5-3wt% of curing agent, and 0.5-3wt% of solvent.

10. A method for preparing electrochromic glass, characterized in that: The preparation method comprises: coating a conductive silver paste on a device substrate on which an electrochromic glass functional layer is prepared, curing the device by the curing method according to any one of claims 1 to 9, and completing packaging to obtain the electrochromic glass.

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