A tab tape with excellent insulation and corrosion resistance and its preparation method

Abstract

This invention relates to the field of adhesive tape technology, specifically disclosing a tab tape with excellent insulation and corrosion resistance, and its preparation method. The tab tape sequentially comprises a PI substrate layer and an acrylic pressure-sensitive adhesive layer on its upper surface. The tab tape provided by this invention has excellent insulation and adhesion performance, and its resistance to electrolyte corrosion is significantly improved compared to existing tab tapes, exhibiting good long-term stability.

Description

Technical Field

[0001] This invention belongs to the field of adhesive tape technology, and specifically relates to an electrode tab tape with good insulation and corrosion resistance, and its preparation method. Background Technology

[0002] In the assembly and production process of lithium-ion batteries, special tapes are generally used to fix, insulate, and protect the tabs of the lithium-ion batteries, preventing direct contact between the electrode and the aluminum-plastic film that could cause a short circuit. Currently, tab tapes are generally developed using acrylic adhesive systems to improve electrolyte resistance and enhance adhesion to the polyimide (PI) substrate and the tabs.

[0003] Currently, acrylic adhesives are commonly used to coat PI films to create tab tapes. While acrylic tab tapes exhibit good adhesion and are less prone to peeling during battery assembly, demonstrating good fixation and insulation, they also have poor electrolyte resistance and are prone to delamination.

[0004] Invention patent CN114015056 A discloses a voltage-resistant and electrolyte-resistant copolymer, a tab adhesive, and a tab tape. This copolymer introduces dicyclopentadienyl acrylate and acrylamidopropylheptyl-cage polysilsesquioxane into the side chains of a polyacrylate colloid, which crosslink with a curing agent to form an interpenetrating network three-dimensional crosslinked structure. The resulting tab adhesive maintains good adhesion of the polyacrylate system and also exhibits excellent voltage resistance and electrolyte resistance. However, it involves a variety of complex special monomers, resulting in high cost and limited applicability. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an electrode tab tape with excellent insulation and corrosion resistance, as well as a method for its preparation. The electrode tab tape provided by this invention exhibits superior insulation and adhesion, and its resistance to electrolyte corrosion is significantly improved compared to existing electrode tab tapes, demonstrating good long-term stability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides an electrode tab tape with good insulation and corrosion resistance, wherein the electrode tab tape comprises a PI substrate layer and an acrylic pressure-sensitive adhesive layer on its upper surface.

[0007] In some embodiments of the present invention, the thickness of the tab tape is 65~85μm.

[0008] Another aspect of the present invention provides a method for preparing an electrode tab tape with good insulation and corrosion resistance, comprising the following steps: taking a PI substrate as a PI substrate layer with a thickness of 20~30μm, coating an acrylic pressure-sensitive adhesive on the upper surface of the PI substrate layer to form an acrylic pressure-sensitive adhesive layer with a thickness of 45~55μm, thereby forming the tape body, drying and shaping the tape body, and then cutting, marking and packaging it to obtain the electrode tab tape.

[0009] In some embodiments of the present invention, the acrylic pressure-sensitive adhesive comprises the following raw materials in parts by weight: 30-60 parts polyacrylic acid resin, 0.5-1 part green ink and 0.8-2.4 parts isocyanate curing agent.

[0010] In some embodiments of the present invention, the preparation steps of the polyacrylic acid resin are as follows: (1) Add isoflurane diisocyanate to the reactor, add hydroxybutyl acrylate dropwise at 25~30℃, add catalyst, keep the reaction at 5~6h, raise the temperature to 80~90℃, add perfluorooctanol dropwise, add catalyst, keep the reaction at 2~3h to obtain fluorine-modified monomer. (2) Add n-butyl acrylate, methyl methacrylate, fluorinated monomer, hydroxyethyl acrylate and acrylic acid to a solvent and mix them evenly to obtain a mixture. Take 30-40 wt% of the mixture, add an initiator, stir and react for 30-40 min under an inert atmosphere, raise the temperature to 75-80℃, add the remaining mixture dropwise, add the initiator after the dropwise addition is complete, continue to keep the temperature and react for 3-5 h, cool, and the polyacrylic acid resin is obtained.

[0011] In some embodiments of the present invention, the mass ratio of isoflurane diisocyanate, hydroxybutyl acrylate and perfluorooctyl alcohol in step (1) is 1:(0.35~0.4):(1.2~1.7).

[0012] In some embodiments of the present invention, the mass ratio of n-butyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic acid in step (2) is (72~77):(8~10):(5~8):(3~5).

[0013] In some embodiments of the present invention, in step (2), the mass of the fluorinated monomer is 7 to 9% of the total mass of n-butyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic acid.

[0014] This invention prepares a copolymer of fluorinated modified monomers and acrylic monomers. When the fluorinated modified monomers migrate to the surface of the pressure-sensitive adhesive, they maintain the inner layer structure of the adhesive while improving the resistance to electrolyte corrosion. This is likely due to the spatial order introduced by the rigid rings, and the hydrogen bonding formed with the hydroxyl groups on the polyacrylic resin polymer segments. These factors together restrict the migration or rearrangement of the fluorinated modified monomers as the usage environment changes, making them less prone to detachment from the polymer segments. This suppresses phase separation phenomena that often occur during long-term use, improving stability. While enhancing corrosion resistance, it does not affect flexibility and conformability, avoiding adverse effects on adhesion and the conformability of the tape itself. Simultaneously, the presence of rigid rings and flexible segments introduced by the fluorinated modified monomers, in conjunction with other acrylic monomers in the system, forms a dense and corrosion-resistant cross-linked protective network, further improving the weather resistance and stability of the acrylic pressure-sensitive adhesive.

[0015] In some embodiments of the present invention, the preparation steps of the acrylic pressure-sensitive adhesive are as follows: Mix polyacrylic resin, isocyanate curing agent and green ink, stir evenly, and wait until the bubbles are completely eliminated to obtain acrylic pressure-sensitive adhesive.

[0016] In some embodiments of the present invention, the isocyanate curing agent is isophorone diisocyanate.

[0017] In some embodiments of the present invention, the PI substrate is a PI substrate obtained by corona treatment.

[0018] In some embodiments of the present invention, the power of the corona treatment is 1~2.5kW.

[0019] This invention preferably uses PI as the substrate and performs corona treatment on it, which reduces surface defects, further enhances the diffusion ability of surface charge, effectively reduces dielectric loss, improves long-term reliability, and gives the tab tape excellent insulation properties; at the same time, the increase of polar groups also improves the bonding effect between the PI substrate and the acrylic pressure-sensitive adhesive layer, and enhances the peel strength.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The tab tape provided by the present invention has good insulation and good adhesion, and its resistance to electrolyte corrosion is greatly improved compared with the existing tab tape, and its long-term stability is good.

[0021] (2) The present invention prepares a copolymer of fluorinated modified monomer and acrylic monomer, which effectively improves the electrolyte corrosion resistance of the tab tape. While enhancing the corrosion resistance, it does not affect the flexibility and conformability, thus avoiding adverse effects on the adhesion and conformability of the tape body. At the same time, possibly due to the presence of rigid rings and flexible segments introduced by the fluorinated modified monomer, the other acrylic monomers in the system form a dense and corrosion-resistant cross-linked protective network, which further improves the weather resistance and stability of the acrylic pressure-sensitive adhesive.

[0022] (3) In this invention, PI is preferred as the substrate and corona treatment is applied to it to reduce surface defects, further enhance the diffusion ability of surface charge, effectively reduce dielectric loss, improve long-term reliability, and make the tab tape have excellent insulation properties. At the same time, the increase of polar groups also improves the bonding effect between the PI substrate and the acrylic pressure-sensitive adhesive layer, and improves the peel strength. Detailed Implementation

[0023] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0024] Unless otherwise specified, all reagents used below are readily available from commercial companies.

[0025] Preparation Example 1 The preparation steps of polyacrylic acid resin are as follows: (1) Add 10g of isoflurane diisocyanate to the reactor, add 3.8g of hydroxybutyl acrylate dropwise over 0.8h at 28℃, add 1 drop of dibutyltin dilaurate, keep the reaction at the temperature for 5.5h, raise the temperature to 85℃, add 15g of perfluorooctyl alcohol dropwise over 1.5h, add 1 drop of dibutyltin dilaurate, keep the reaction at the temperature for 2.5h to obtain fluorine-modified monomer; (2) 75g of n-butyl acrylate, 9g of methyl methacrylate, 7.6g of fluorinated monomer, 7g of hydroxyethyl acrylate and 4g of acrylic acid were added to 150mL of ethyl acetate and mixed evenly to obtain a mixture. 35wt% of the mixture was taken and 0.2g of azobisisobutyronitrile was added. The mixture was stirred and reacted for 35min under a nitrogen atmosphere. The temperature was raised to 78℃ and the remaining mixture was added dropwise over 2.5h. After the addition was completed, 0.1g of azobisisobutyronitrile was added and the mixture was kept at the temperature for 4h. After cooling, polyacrylic acid resin was obtained.

[0026] Preparation Example 2 The specific preparation steps of polyacrylic acid resin are the same as those in Preparation Example 1, except that the amount of hydroxybutyl acrylate added in step (1) is 4.2g.

[0027] Preparation Example 3 The specific preparation steps of polyacrylic acid resin are the same as those in Preparation Example 1, except that the amount of perfluorooctanoic acid added in step (1) is 18g.

[0028] Preparation Example 4 The specific preparation steps of polyacrylic resin are the same as those in Preparation Example 1, except that in step (1), hydroxyethyl methacrylate is used instead of hydroxybutyl acrylate in an equal molar amount.

[0029] Preparation Example 5 The specific preparation steps of polyacrylic acid resin are the same as those in Preparation Example 1, except that the amount of fluorinated modified monomer added in step (2) is 9.5g.

[0030] Preparation Example 6 The specific preparation steps of polyacrylic acid resin are the same as those in Preparation Example 1, except that in step (2), the fluorine-modified monomer is replaced by an equal molar amount of dodecafluoroheptyl methacrylate.

[0031] Preparation Example 7 The preparation steps of acrylic pressure-sensitive adhesive are as follows: By weight, 45 parts of polyacrylic resin, 1.6 parts of isophorone diisocyanate and 0.7 parts of green ink are mixed and stirred until the bubbles are completely eliminated to obtain acrylic pressure-sensitive adhesive.

[0032] The polyacrylic acid resin used was obtained from Preparation Example 1.

[0033] Preparation Example 8 The preparation steps of acrylic pressure-sensitive adhesive are as follows: By weight, mix 30 parts of polyacrylic acid resin, 0.8 parts of isophorone diisocyanate and 0.5 parts of green ink, stir evenly, and wait until the bubbles are completely eliminated to obtain acrylic pressure-sensitive adhesive.

[0034] The polyacrylic acid resin used was obtained from Preparation Example 1.

[0035] Preparation Example 9 The preparation steps of acrylic pressure-sensitive adhesive are as follows: By weight, 60 parts of polyacrylic acid resin, 2.4 parts of isophorone diisocyanate and 1 part of green ink are mixed and stirred until the bubbles are completely eliminated to obtain acrylic pressure-sensitive adhesive.

[0036] The polyacrylic acid resin used was obtained from Preparation Example 1.

[0037] Preparation Example 10 The specific preparation steps of the acrylic pressure-sensitive adhesive are the same as those in Preparation Example 7, except that the polyacrylic acid resin used is obtained from Preparation Example 2.

[0038] Preparation Example 11 The specific preparation steps of the acrylic pressure-sensitive adhesive are the same as those in Preparation Example 7, except that the polyacrylic acid resin used is obtained from Preparation Example 3.

[0039] Preparation Example 12 The specific preparation steps of the acrylic pressure-sensitive adhesive are the same as those in Preparation Example 7, except that the polyacrylic acid resin used is obtained from Preparation Example 4.

[0040] Preparation Example 13 The specific preparation steps of the acrylic pressure-sensitive adhesive are the same as those in Preparation Example 7, except that the polyacrylic acid resin used is obtained from Preparation Example 5.

[0041] Preparation Example 14 The specific preparation steps of the acrylic pressure-sensitive adhesive are the same as those in Preparation Example 7, except that the polyacrylic acid resin used is obtained from Preparation Example 6.

[0042] Example 1 A method for preparing a tab tape with good insulation and corrosion resistance includes the following steps: taking a PI substrate as the PI substrate layer with a thickness of 25μm, coating an acrylic pressure-sensitive adhesive on the upper surface of the PI substrate layer to form an acrylic pressure-sensitive adhesive layer with a thickness of 50μm, forming the tape body, drying and shaping the tape body, and then cutting, marking and packaging it to obtain the tab tape with a thickness of 75μm. The acrylic pressure-sensitive adhesive used was prepared in Preparation Example 7; The PI substrate used was subjected to a 2kW corona treatment.

[0043] Example 2 A method for preparing an insulating and corrosion-resistant tab tape includes the following steps: taking a PI substrate as the PI substrate layer with a thickness of 20 μm, coating an acrylic pressure-sensitive adhesive on the upper surface of the PI substrate layer to form an acrylic pressure-sensitive adhesive layer with a thickness of 45 μm, forming the tape body, drying and shaping the tape body, and then cutting, marking and packaging it to obtain the tab tape with a thickness of 65 μm. The acrylic pressure-sensitive adhesive used was prepared in Preparation Example 8; The PI substrate used was subjected to a 1kW corona treatment.

[0044] Example 3 A method for preparing an insulating and corrosion-resistant tab tape includes the following steps: taking a PI substrate as the PI substrate layer with a thickness of 30μm, coating an acrylic pressure-sensitive adhesive on the upper surface of the PI substrate layer to form an acrylic pressure-sensitive adhesive layer with a thickness of 55μm, forming the tape body, drying and shaping the tape body, and then cutting, marking and packaging it to obtain the tab tape with a thickness of 85μm. The acrylic pressure-sensitive adhesive used was prepared in Preparation Example 9; The PI substrate used was subjected to a 2.5kW corona treatment.

[0045] Example 4 A method for preparing an insulating and corrosion-resistant tab tape is described, with the specific implementation method being the same as in Example 1, except that the acrylic pressure-sensitive adhesive used is prepared in Preparation Example 10.

[0046] Example 5 A method for preparing an insulating and corrosion-resistant tab tape is described, with the specific implementation method being the same as in Example 1, except that the acrylic pressure-sensitive adhesive used is prepared in Preparation Example 11.

[0047] Example 6 A method for preparing an insulating and corrosion-resistant tab tape is described, with the specific implementation method being the same as in Example 1, except that the acrylic pressure-sensitive adhesive used is prepared in Preparation Example 12.

[0048] Example 7 A method for preparing an insulating and corrosion-resistant tab tape is described, with the specific implementation method being the same as in Example 1, except that the acrylic pressure-sensitive adhesive used is prepared in Preparation Example 13.

[0049] Example 8 A method for preparing an insulating and corrosion-resistant tab tape is described, with the specific implementation method being the same as in Example 1, except that the acrylic pressure-sensitive adhesive used is prepared in Preparation Example 14.

[0050] Example 9 A method for preparing an insulating and corrosion-resistant tab tape is described, with the specific implementation method being the same as in Example 1, except that the PI substrate used is not subjected to corona treatment.

[0051] Performance testing: The tab tapes prepared in Examples 1-9 above were subjected to the following performance tests, and the specific test results are shown in Table 1: (1) Insulation performance test: The tab tapes prepared in Examples 1-3 and Example 9 were placed in an environment with a temperature of 25°C and a humidity of 50%RH for 24 hours. The DC breakdown voltage of each tab tape was tested according to the ASTM D149 standard. The test results are shown in Table 1. (2) Peel strength test: The 180° peel strength of the tab tapes prepared in each embodiment was tested using a BLD-200S electronic glass testing machine according to standard GB / T 2792-2014 at a peel speed of 300 mm / min. The test results are shown in Table 2. (3) Corrosion performance test: The electrode tapes prepared in each embodiment were subjected to high voltage lithium-ion electrolyte resistance test. Specifically, after soaking in high voltage lithium-ion electrolyte for 24 hours at 85°C, the 180° peel strength after soaking was obtained by reference performance test (2). The 180° peel strength retention rate was calculated. 180° peel strength retention rate = 180° peel strength after soaking / 180° peel strength × 100%. The test results are shown in Table 2.

[0052] Table 1

[0053] As shown in Table 1, the tab tapes disclosed in Examples 1-3 of this invention have good insulation properties. However, in Example 9, no further treatment was performed on the PI substrate, resulting in a decrease in the insulation performance of the tab tape.

[0054] Table 2

[0055] As shown in Table 2, the tab tapes disclosed in Examples 1-3 of this invention have good adhesive properties and good resistance to electrolyte corrosion.

[0056] A comparison of Examples 4 and 5 with Example 1 shows that Examples 4 and 5, by changing the amounts of hydroxybutyl acrylate and perfluorooctyl alcohol, respectively, affected the purity of the fluorinated monomers, thus affecting the polymerization of polyacrylate and leading to a decrease in the overall performance of the polyacrylic resin. This, in turn, affected the adhesive properties and electrolyte corrosion resistance of the tab tape. A comparison of Example 6 with Example 1 shows that Example 6, by replacing hydroxybutyl acrylate with an equimolar amount of hydroxyethyl methacrylate, may have caused the fluorinated monomers to affect the wetting of the acrylic pressure-sensitive adhesive layer and the PI substrate layer, resulting in a significant decrease in adhesion. A comparison of Example 7 with Example 1 shows that… Example 7 changed the amount of fluorinated modified monomer added, which may have caused phase separation due to compatibility issues, and the internal stress of the cured adhesive layer was concentrated, resulting in varying degrees of decrease in peel strength and resistance to electrolyte corrosion. Comparing Example 8 and Example 1, it can be seen that when Example 8 replaced the fluorinated modified monomer with an equimolar amount of dodecafluoroheptyl methacrylate, the distribution of the fluorocarbon chain was loose and disordered, which had a significant impact on the electrolyte corrosion resistance of the tab tape. Comparing Example 9 and Example 1, it can be seen that Example 9 did not further treat the PI substrate, resulting in insufficient interlayer force between the acrylic pressure-sensitive adhesive layer and the PI substrate, and a decrease in the overall performance of the tab tape.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A type of electrode tab tape with excellent insulation and corrosion resistance, characterized in that, The tab tape comprises a PI substrate layer and an acrylic pressure-sensitive adhesive layer on its upper surface.

2. The electrode tab tape with excellent insulation and corrosion resistance according to claim 1, characterized in that, The thickness of the tab tape is 65~85μm.

3. A method for preparing the electrode tab tape with good insulation and corrosion resistance as described in claim 1 or 2, characterized in that, The process includes the following steps: taking a PI substrate as the PI substrate layer with a thickness of 20~30μm, coating an acrylic pressure-sensitive adhesive on the upper surface of the PI substrate layer to form an acrylic pressure-sensitive adhesive layer with a thickness of 45~55μm, and forming the tape body. The tape body is dried and shaped, and then cut, labeled and packaged to obtain the tab tape.

4. The method for preparing the electrode tab tape with good insulation and corrosion resistance according to claim 3, characterized in that, The acrylic pressure-sensitive adhesive comprises the following raw materials in parts by weight: 30-60 parts polyacrylic acid resin, 0.5-1 part green ink, and 0.8-2.4 parts isocyanate curing agent.

5. The method for preparing the electrode tab tape with good insulation and corrosion resistance according to claim 4, characterized in that, The preparation steps of the polyacrylic acid resin are as follows: (1) Add isoflurane diisocyanate to the reactor, add hydroxybutyl acrylate dropwise at 25~30℃, add catalyst, keep the reaction at 5~6h, raise the temperature to 80~90℃, add perfluorooctanol dropwise, add catalyst, keep the reaction at 2~3h to obtain fluorine-modified monomer. (2) Add n-butyl acrylate, methyl methacrylate, fluorinated monomer, hydroxyethyl acrylate and acrylic acid to a solvent and mix them evenly to obtain a mixture. Take 30-40 wt% of the mixture, add an initiator, stir and react for 30-40 min under an inert atmosphere, raise the temperature to 75-80℃, add the remaining mixture dropwise, add the initiator after the dropwise addition is complete, continue to keep the temperature and react for 3-5 h, cool, and the polyacrylic acid resin is obtained.

6. The method for preparing the electrode tab tape with good insulation and corrosion resistance according to claim 5, characterized in that, The mass ratio of isoflurane diisocyanate, hydroxybutyl acrylate and perfluorooctyl alcohol in step (1) is 1: (0.35~0.4): (1.2~1.7).

7. The method for preparing the electrode tab tape with good insulation and corrosion resistance according to claim 5, characterized in that, In step (2), the mass of the fluorinated monomer is 7-9% of the total mass of n-butyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic acid.

8. The method for preparing the insulating and corrosion-resistant tab tape according to claim 4, characterized in that, The isocyanate curing agent is isophorone diisocyanate.

9. The method for preparing the electrode tab tape with good insulation and corrosion resistance according to claim 3, characterized in that, The PI substrate is a PI substrate obtained through corona treatment.

10. The method for preparing the electrode tab tape with good insulation and corrosion resistance according to claim 9, characterized in that, The power of the corona treatment is 1~2.5kW.

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