A method for repairing battery blue film

Abstract

The present invention relates to a method for repairing a battery blue film, and belongs to the technical field of packaging repair. The present invention provides a method for repairing a battery blue film, comprising the following steps: (1) grinding the damaged part of the blue film to make it smooth; (2) performing functional group modification on the damaged part of the blue film after grinding, so that its surface has functional groups that can react with UV glue; (3) spraying UV glue on the damaged part of the blue film by a spray dispensing method, and then performing UV curing. The blue film repair method of the present invention performs functional group modification on the damaged part, so that the glue reacts with the modified blue film surface, thereby increasing the peeling strength between the glue and the damaged part of the blue film, and replaces the existing patching method with the dispensing method, so that the obtained battery has good insulation performance and good appearance, does not affect the user experience, reduces the rework rate, and improves production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of packaging repair, and in particular relates to a method for repairing a battery blue film. Background Art

[0002] The last step in the preparation of lithium-ion batteries is to wrap the battery with a layer of blue protective film (referred to as "blue film"). During the coating process, bubbles and wrinkles are easily generated, and during the battery transportation process, the blue film is easily damaged, resulting in problems such as damage to the blue film. The existing treatment plan is to tear off the blue film that produces bubbles or wrinkles and re-wrap it, but this method has defects such as high raw material costs, waste of working hours and manpower. Although the insulation effect can be achieved by spraying glue to repair the damaged position, and unnecessary rework can be reduced, reducing the cost of the battery, the existing glue is difficult to use directly after spraying, and there are problems such as low peeling force, color mismatch after spraying, and the thickness of the spraying cannot be well controlled. Summary of the invention

[0003] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and provide a method for repairing battery blue film by dispensing glue instead of the existing patching and spraying glue, so that the blue film has high peeling strength and good battery insulation after repair.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention provides a method for repairing a battery blue film, comprising the following steps:

[0006] (1) Grind the damaged part of the blue film smooth;

[0007] (2) Performing functional group modification on the damaged part of the blue film after polishing so that its surface has functional groups that can react with UV glue;

[0008] (3) Use the spray dispensing method to spray UV glue on the damaged part of the blue film, and then perform UV curing.

[0009] The present invention polishes the excess blue film or residual glue at the damaged part of the blue film to the same level as the undamaged part, which is convenient for the flatness of the subsequent spraying of the glue layer. The damaged part of the blue film is functionally modified so that its surface has functional groups that can react with UV glue, thereby enhancing the adhesion between the adhesive and the blue film surface substrate and increasing the peeling strength between the adhesive and the damaged part. Further, the existing patching and spraying method is replaced by the dispensing method, so that the repaired lithium-ion battery has good insulation performance and good appearance, does not affect the user experience, reduces the rework rate, and improves production efficiency.

[0010] Preferably, the blue film damage of the present invention includes but is not limited to blue film blister, blue film wrinkle, blue film missing and damaged. The blue film damage of the present invention can be a blue film with poor appearance, such as blue film blister and blue film wrinkle, or a blue film missing and damaged caused by external force.

[0011] As a preferred embodiment of the battery blue film repair method of the present invention, in the step (1), before the polishing, the damaged part of the blue film is subjected to laser ablation or hardware hole cutting.

[0012] After the blue film is damaged, it is easy to adhere to the outer surface of the battery and produce wrinkles. Before polishing, laser ablation or hardware hole cutting is used to peel off the blue film adhered to the surface, and then the blue film is polished, which can better process the blue film and facilitate the next step of spray dispensing. The polishing can be mechanical polishing, and specifically can be performed using tools such as sandpaper or files.

[0013] As a preferred embodiment of the battery blue film repair method of the present invention, the step (1) further comprises the following steps: after polishing, cleaning the damaged part of the blue film. Preferably, the cleaning is to wipe the polished damaged part of the blue film with alcohol or non-woven fabric.

[0014] During the polishing process, impurities produced by polishing may remain at the damaged part of the blue film, and the presence of impurities will affect the adhesion of the subsequent adhesive layer. Therefore, the impurities are removed by cleaning the damaged part of the blue film after polishing to avoid the influence of impurities on the adhesion of the adhesive layer.

[0015] As a preferred embodiment of the method for repairing the battery blue film of the present invention, in the step (2), the method for modifying the functional group includes at least one of corona discharge, plasma irradiation, and electron beam radiation.

[0016] The present invention does not impose any special restrictions on the time for functional group modification, which can be selected according to the area of ​​blue film damage, and is preferably 30s-5min.

[0017] Before the damaged part of the blue film is modified with functional groups, the reaction principle between the blue film and the UV adhesive is: X-COOH+HCY→X-COOH…HCY, where X is the main chain of the adhesive and Y is the surface substrate of the blue film. The chemical reaction between the blue film and the adhesive is very weak. However, after the damaged part of the blue film is modified with functional groups so that its surface has functional groups that can react with UV adhesive, the reaction principle between the blue film and the UV adhesive is: X-COOH+HO-CY→X-CO-OC-Y+H2O. By modifying the surface substrate of the blue film, the surface has functional groups that can react with the photocurable acrylate adhesive, thereby enhancing the adhesion between the blue film and the adhesive and greatly improving the repair effect.

[0018] As a preferred embodiment of the battery blue film repair method of the present invention, the UV glue is an acrylate photocuring adhesive, the viscosity of the acrylate photocuring adhesive is 2000cps-3500cps, the bonding strength with the blue film is 1MPa-5MPa, and the color is Pantone 2728C-2748C or Pantone285C-288C.

[0019] Specifically, the color of the UV glue is Pantone 2728C, Pantone 2738C, Pantone 2748C, Pantone 285C, Pantone 286C, Pantone 287C or Pantone 288C.

[0020] As a preferred embodiment of the battery blue film repair method of the present invention, in the step (3), the wavelength of the UV curing is 300nm-400nm, specifically, it can be 300nm, 320nm, 365nm, 385nm, 395nm; the time is 10s-60s, specifically, it can be 10s, 20s, 30s, 40s, 50s, 60s.

[0021] The viscosity, color and bonding strength of the adhesive will affect the blue film repair effect. Acrylic light-curing adhesive has the advantages of fast deep curing and good surface drying. The preferred acrylic light-curing adhesive of the present invention has a moderate viscosity. When it is not within the preferred range, too high a viscosity will cause the sprayed adhesive to be too thick, and too low a viscosity will cause the sprayed adhesive to not form a film, resulting in a poor repair effect, that is, too low a bonding strength will lead to a poor bonding effect; too large a color difference will affect the appearance. The preferred acrylic light-curing adhesive of the present invention has an appropriate viscosity and good bonding strength to the blue film, so that the insulation performance of the repaired battery is good, the appearance is good, and the use experience is not affected.

[0022] As a preferred embodiment of the battery blue film repair method of the present invention, in the step (3), a needle-type spray valve is used for spray dispensing, and the working air pressure of the needle-type spray valve is 4kgf / cm 2 -7kgf / cm 2 , feed pressure <10kg.

[0023] As a preferred embodiment of the battery blue film repair method of the present invention, in the step (3), the amount of glue spitted each time in the spray dispensing method is 0.01-0.1ml. Specifically, it can be 0.01ml, 0.02ml, 0.04ml, 0.06ml, 0.08ml, 0.1ml. By controlling the amount of glue spitted, on the one hand, it can be avoided that the amount of glue spitted is too small, resulting in multiple glue coating times, and on the other hand, it can be avoided that the amount of glue spitted is too large, resulting in difficulty in scraping to a suitable thickness. The specific amount of glue spitted can be selected according to the area of ​​the blue film damage.

[0024] As a preferred embodiment of the battery blue film repair method of the present invention, in step (3), the thickness of the adhesive coating after spraying is 0.02mm-0.2mm. By controlling the thickness of the coating, the thickness difference between the coating and the blue film can be controlled within a suitable range, on the one hand to ensure the insulation performance of the coating; on the other hand, it can avoid the coating from protruding obviously from the blue film to ensure a good appearance.

[0025] The present invention preferably adopts a spray dispensing method, which ensures that the thickness of the glue layer is moderate by controlling the number of spraying times, thereby avoiding color difference affecting the appearance. Before UV curing, the UV glue can be scraped to make it flat. In addition, the glue layer of the repair method of the present invention can be wiped off with alcohol, which is conducive to rework of abnormal glue coating, is convenient to operate, and improves production efficiency.

[0026] The invention has the following beneficial effects: the blue film repair method of the invention performs functional group modification on the damaged part, so that the glue reacts with the modified blue film surface, thereby increasing the peel strength between the glue and the damaged part of the blue film, and replaces the existing patching method by dispensing glue, so that the obtained battery has good insulation performance and good appearance, and the appearance effect is as follows: Figure 3 As shown, there is no color difference at the damaged part, and the patch repair method is as follows Figure 2 As shown, color difference and poor bonding strength will occur. The peel strength of the coating obtained by the method of the present invention with the blue film can reach 20N / m-90N / m, and the peel strength with the battery shell can reach 400N / m-700N / m. The peel strength is high, does not affect the use experience, reduces the rework rate, and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the damage of the blue film of a lithium-ion battery coating; wherein 1 is the top cover and the top cover patch, 2 is the positive pole, 3 is the explosion-proof valve, 4 is the QR code, 5 is the negative pole, 6 is the blue film, and 7 is the location of the damage of the blue film;

[0028] Figure 2A schematic diagram of spraying and patching a damaged blue film of a lithium-ion battery coating; 1 is the top cover and the top cover patch, 2 is the positive pole, 3 is the explosion-proof valve, 4 is the QR code, 5 is the negative pole, 6 is the blue film, and 8 is the patching situation;

[0029] Figure 3 It is a schematic diagram of a damaged point of a blue film of a lithium-ion battery coating after being repaired by the repair method of the present invention; wherein 1 is a top cover and a top cover patch, 2 is a positive pole, 3 is an explosion-proof valve, 4 is a QR code, 5 is a negative pole, 6 is a blue film, and 9 is a dispensing situation; the black one is a dispensing machine. DETAILED DESCRIPTION

[0030] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] Unless otherwise specified, the experimental methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0032] Example 1

[0033] A method for repairing a battery blue film comprises the following steps:

[0034] (1) For incoming battery materials, manually identify the damaged position of the blue film, smooth the damaged part with sandpaper, and reshape the excess blue film at the damaged part to the level of the undamaged part;

[0035] (2) Wipe the polished and leveled area with alcohol, and perform functional group modification on the damaged area of ​​the leveled blue film by corona discharge, so that the surface has functional groups that can react with UV glue;

[0036] (3) Manual high-frequency spray dispensing, the working air pressure of the ejector spray valve is 4kgf / cm 2 The feeding pressure is 6kg, the micrometer is fine-tuned, the glue spitting amount each time is 0.01ml, and after multiple spraying, the UV glue is scraped flat, and the thickness of the adhesive coating obtained after UV curing is 0.02mm; the UV glue used is an acrylic light-curing adhesive with a viscosity of 2000cps, a bonding blue film strength of 1MPa, and a color of Pantone 2748C; then the sprayed battery is placed in a UV oven and light-cured under 365nm ultraviolet light for 10s to obtain the required intact battery after glue repair.

[0037] The blue film after repair in this embodiment has a good appearance without color difference, and the obtained battery has good insulation performance.

[0038] If the damaged blue film is not polished in step (1), the glue layer after glue application will be uneven and produce burrs. If the leveled blue film is not wiped with alcohol in step (2), the adhesive force of the glue layer after glue application will decrease and the durability will be poor.

[0039] Example 2

[0040] A method for repairing a battery blue film comprises the following steps:

[0041] (1) For incoming battery materials, the damaged position of the blue film is manually identified, the damaged part of the blue film is flattened by laser ablation, and the blue film at the damaged part is reshaped to the level of the undamaged part;

[0042] (2) Wipe the polished and leveled area with alcohol, and perform functional group modification on the damaged area of ​​the leveled blue film by electron beam radiation, so that the surface has functional groups that can react with UV glue;

[0043] (3) Manual high-frequency spray dispensing, the working air pressure of the ejector spray valve is 7kgf / cm 2 The feeding pressure is 6kg, the micrometer is fine-tuned, and the glue dispensing amount is 0.01ml each time. After multiple spraying, the UV glue is scraped flat, and the thickness of the adhesive coating obtained after UV curing is 0.2mm; the UV glue used is an acrylic light-curing adhesive with a viscosity of 3500cps, a bonding blue film strength of 5MPa, and a color of Pantone285C. Then, the sprayed battery is placed in a UV oven and light-cured under 365nm ultraviolet light for 60s to obtain the required intact battery after glue repair.

[0044] The blue film after repair in this embodiment has a good appearance without color difference, and the obtained battery has good insulation performance.

[0045] Example 3

[0046] A method for repairing a battery blue film comprises the following steps:

[0047] (1) For incoming battery materials, the damaged position of the blue film is manually identified, the damaged part of the blue film is flattened by laser ablation, and the blue film at the damaged part is reshaped to the level of the undamaged part;

[0048] (2) Wipe the polished and leveled area with alcohol, and perform functional group modification on the damaged area of ​​the leveled blue film by plasma irradiation, so that the surface has functional groups that can react with UV glue;

[0049] (3) Manual high-frequency spray dispensing, the working air pressure of the ejector spray valve is 6kgf / cm 2The feeding pressure is 6kg, the micrometer is fine-tuned, and the glue spraying amount is 0.01ml each time. After multiple spraying, the battery UV glue is scraped flat, and the thickness of the adhesive coating obtained after UV curing is 0.1mm; the UV glue used is an acrylic light-curing adhesive with a viscosity of 3000cps, a bonding blue film strength of 2MPa, and a color of Pantone 288C. Then put the sprayed battery into the UV oven and light-cured under 365nm ultraviolet light for 40s to obtain the required intact battery after glue repair.

[0050] The blue film after repair in this embodiment has a good appearance without color difference, and the obtained battery has good insulation performance.

[0051] Comparative Example 1

[0052] The only difference between the blue film repair method of this comparative example and Example 1 is that the viscosity of the UV glue used is 1000cps, and the rest are the same. Since the viscosity of the UV glue is too low to form a film, the blue film after repair in this comparative example has low peeling force and poor bonding strength.

[0053] Comparative Example 2

[0054] A method for repairing a battery blue film comprises the following steps:

[0055] (1) For incoming battery materials, the damaged position of the blue film is manually identified, the damaged part of the blue film is flattened by laser ablation, and the blue film at the damaged part is reshaped to the level of the undamaged part;

[0056] (2) Wipe the polished and leveled area with alcohol, and perform functional group modification on the damaged area of ​​the leveled blue film by plasma irradiation, so that the surface has functional groups that can react with UV glue;

[0057] (3) Manual high-frequency spray dispensing, the working air pressure of the ejector spray valve is 6kgf / cm 2 The feeding pressure is 6kg, the micrometer is fine-tuned, and the glue ejection amount is 0.01ml each time. After multiple spraying (the same number of spraying times as in Example 1), the battery UV glue is scraped and UV cured; the UV glue used is an acrylic light-curing adhesive with a viscosity of 4500cps, a bonding blue film strength of 2MPa, and a color of Pantone288C. Then, the sprayed battery is placed in a UV oven and light-cured under 365nm ultraviolet light for 40s to obtain the required intact battery after glue repair.

[0058] The difference between the blue film repair method of this comparative example and Example 1 is that the viscosity of the UV glue used is 4500cps. At this time, due to the high viscosity of the UV glue, the UV glue is difficult to be scraped flat, and thus a flat adhesive layer with a thickness of 0.02mm cannot be obtained. Therefore, although the UV glue at this viscosity will have a good bonding strength, due to the high viscosity of the UV glue, the glue layer obtained by spraying is difficult to be scraped flat, and a coating with moderate thickness and flatness cannot be obtained, resulting in bulges on the blue film at the repaired part, poor flatness, and poor appearance.

[0059] Comparative Example 3

[0060] The blue film repair method of this comparative example is different from that of Example 1 in that the damaged part of the blue film is not functionally modified, and the rest are the same. The repaired blue film has low adhesion and poor repair effect.

[0061] Comparative Example 4

[0062] The difference between the blue film repair method of this comparative example and Example 1 is that the color of the UV glue used is Pantone 2725C, and the rest are the same. After repair, there is an obvious color difference between the coating and the blue film, and the appearance is poor.

[0063] The peel strength of the adhesive layer of Examples 1-3 and Comparative Examples 1 and 3 with the aluminum shell and the blue film was tested, and the test standard was GB2792-1988, 180°. The test method was: 2 cm wide adhesive was applied on the aluminum shell / blue film, one end was torn open, and a strip of blue film was used to stick it tightly, and a tensile test machine was used to perform a peel strength test, and the test results are shown in Table 1.

[0064] Table 1 Peel strength of the adhesive layer between Examples 1-3 and Comparative Examples 1 and 3 and the aluminum shell and blue film

[0065] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 3 Glue-blue film peel strength (N / m) 40 90 60 5 12 Glue-aluminum shell peel strength (N / m) 400 700 550 200 70

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for repairing a battery blue film, characterized in that: The following steps are involved: (1) Grind the damaged part of the blue film smooth; (2) Performing functional group modification on the damaged part of the blue film after polishing so that its surface has functional groups that can react with UV glue; (3) Spraying UV glue on the damaged part of the blue film by spray dispensing method, and then UV curing; The UV glue is an acrylic light-curing adhesive, the viscosity of the acrylic light-curing adhesive is 2000cps-3500cps, the bonding strength with the blue film is 1MPa-5MPa, and the color is Pantone 2728C-2748C or Pantone 285C-288C; In the step (3), the amount of glue dispensed each time in the spray dispensing method is 0.01-0.1 ml. Before UV curing, the UV glue is scraped flat, and the thickness of the adhesive coating after spraying is 0.02 mm-0.2 mm.

2. The method for repairing the battery blue film according to claim 1, characterized in that: In the step (1), before polishing, the damaged part of the blue film is subjected to laser ablation or hardware hole cutting.

3. The method for repairing the battery blue film according to claim 1, characterized in that: The step (1) further comprises the following steps: after polishing and leveling, cleaning the damaged part of the blue film.

4. The method for repairing the battery blue film according to claim 1, characterized in that: In the step (2), the method of functional group modification includes at least one of corona discharge, plasma irradiation, and electron beam radiation.

5. The method for repairing the battery blue film according to claim 1, characterized in that: In the step (3), the wavelength of the UV curing is 300nm-400nm, and the time is 10s-60s.

6. The method for repairing the battery blue film according to claim 1, characterized in that: In the step (3), a needle-type spray valve is used for spray dispensing, and the working air pressure of the needle-type spray valve is 4 kgf / cm 2 -7kgf / cm 2 , feed pressure <10kg.

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