High-adhesion adhesive-residue-free insulating battery cell adhesive tape and preparation method thereof

Abstract

The invention relates to the field of adhesive tapes, and provides a high-adhesion residual-adhesive-free insulating battery cell adhesive tape and a preparation method thereof.The adhesive tape sequentially comprises a transparent PET base material layer, an acrylic acid pressure-sensitive adhesive layer, a blue PET base material layer, an acrylic acid pressure-sensitive adhesive layer and a release layer from bottom to top; the acrylic pressure-sensitive adhesive layer is prepared from the following raw materials in parts by weight: 80-100 parts of polyacrylic resin, 1-4 parts of a curing agent, 10-20 parts of modified shellac resin, 4-8 parts of filler, 1-4 parts of an initiator, 0.5-3.5 parts of a coupling agent, 1-3 parts of a dispersing agent and 55-75 parts of a solvent; and the release layer is a PET release layer. The adhesive tape provided by the invention has the characteristics of high adhesion, no adhesive residue, high temperature resistance and good insulation protection effect.

Description

Technical Field

[0001] The present invention relates to the field of adhesive tapes, and in particular to a high-adhesion adhesive-residue-free insulating battery core adhesive tape and a preparation method thereof. Background Art

[0002] With the continuous development of science and technology, people's demand for battery performance continues to increase. Lithium-ion batteries, as a high-performance battery, are becoming more and more popular. Battery tape, as a key auxiliary material for lithium-ion battery cells, is mainly used to isolate the positive and negative electrodes, prevent short circuits, and ensure that the battery remains stable in high temperature, electrolyte and other environments. It also plays an important role in insulation protection. Its performance directly determines the battery cell yield, safety and cycle life.

[0003] At present, most battery tapes are made of PET as the base material and coated with acrylic pressure-sensitive adhesive on its surface. They have the advantages of high cleanliness, easy flushing, excellent battery wrapping and insulation properties, etc. However, there may still be some unresolved defects in actual application. For example, the polyacrylic acid pressure-sensitive adhesive is not stable enough under high temperature and other conditions, which may cause the viscosity of the battery tape to decrease and fail to meet the high viscosity requirements under certain specific conditions. In addition, the battery tape of the acrylic pressure-sensitive adhesive system may also have residual adhesive problems when it is removed.

[0004] Patent CN 112778933 A discloses a high-adhesion, shear-resistant acrylic pressure-sensitive tape. The raw materials for preparing the tape include acrylic hard monomer, acrylic soft monomer, n-butyl methacrylate, solvent, methoxydimethyl ether-modified alkylphenol-formaldehyde resin, isophorone diisocyanate, azo initiator, and polydimethylsiloxane. The tape has high adhesion, shear resistance, and puncture resistance, but does not involve research on high-temperature resistance, and the temperature resistance may not meet the requirements of working in ultra-high temperature environments.

[0005] Therefore, there is an urgent need on the market for a battery core tape that has the characteristics of high adhesion, no residual glue, high temperature resistance and good insulation protection. Summary of the Invention

[0006] In response to the problems existing in the prior art, the present invention selects polyacrylic resin as the main component, designs to add modified shellac resin, and prepares an acrylic pressure-sensitive adhesive in combination with a curing agent, an initiator, a coupling agent, a filler and a dispersant. The acrylic pressure-sensitive adhesive is then combined with a transparent PET substrate layer, a blue PET substrate layer, an acrylic pressure-sensitive adhesive layer and a release layer to form a five-layer adhesive tape with the characteristics of high adhesion, no residual adhesive, high temperature resistance and good insulation protection.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On one hand, the present invention provides a high-bonding and adhesive-residue-free insulating battery tape, which comprises, from bottom to top, a transparent PET substrate layer, an acrylic pressure-sensitive adhesive layer, a blue PET substrate layer, an acrylic pressure-sensitive adhesive layer, and a release layer;

[0009] The acrylic pressure-sensitive adhesive layer is prepared by the following raw materials, calculated by weight: 80-100 parts of polyacrylic resin, 1-4 parts of curing agent, 10-20 parts of modified shellac resin, 4-8 parts of filler, 1-4 parts of initiator, 0.5-3.5 parts of coupling agent, 1-3 parts of dispersant, and 55-75 parts of solvent;

[0010] The release layer is a PET release layer.

[0011] In some embodiments of the present invention, the thickness of the transparent PET substrate layer is 0.028-0.032 mm, the thickness of the acrylic pressure-sensitive adhesive layer is 0.026-0.030 mm, the thickness of the blue PET substrate layer is 0.023-0.027 mm, and the thickness of the release layer is 0.023-0.027 mm.

[0012] In some embodiments of the present invention, the curing agent is an isocyanate curing agent.

[0013] Preferably, the isocyanate curing agent is toluene diisocyanate.

[0014] In some embodiments of the present invention, the method for preparing the modified shellac resin comprises the following steps:

[0015] Mix shellac resin, ethylene glycol bis(thioglycolate), azobisisobutyronitrile and anhydrous ethanol, introduce inert gas, stir at 60-70° C. for 35-37 hours, rotary evaporate and dry to obtain modified shellac resin.

[0016] In some embodiments of the present invention, the mass ratio of the shellac resin to ethylene glycol bis(thioglycolate) is 1:(0.04-0.06).

[0017] Preferably, the mass ratio of the shellac resin to ethylene glycol bis(thioglycolate) is 1:0.05.

[0018] Shellac resin is a natural resin derived from insects. It is non-toxic and biodegradable, and also has excellent adhesion, insulation and wear resistance. Adding it to acrylic pressure-sensitive adhesive can effectively improve the insulation, adhesion and durability of the acrylic pressure-sensitive adhesive, and further prevent the formation of adhesive residue on the tape. However, when shellac resin is stored or transported in a high temperature and high humidity environment, the carbon-carbon double bonds in the sesquiterpene acid components in the shellac resin may cross-link or oxidize, causing the shellac resin to deteriorate and become unusable, which in turn results in the adhesion of the acrylic pressure-sensitive adhesive not being well improved.

[0019] The applicant selected ethylene glycol bis(thioglycolate) as a modifier and modified the shellac resin in the presence of azobisisobutyronitrile as an initiator and anhydrous ethanol as a solvent. The thiol group in the ethylene glycol bis(thioglycolate) structure reacted with the carbon-carbon double bond in the shellac resin, converting the carbon-carbon double bond into a saturated sulfide bond. This imparted to the shellac resin excellent high-temperature resistance and storage stability. The sulfide bond also exhibited excellent bond flexibility, further enhancing the shellac resin's intramolecular toughening properties and effectively improving the mechanical properties of the shellac resin. This resulted in the adhesive tape having the advantages of high-temperature resistance, high adhesion, and no residual adhesive.

[0020] In some embodiments of the present invention, the filler is any one of boehmite, nano-silicon dioxide, and nano-aluminum oxide.

[0021] In some embodiments of the present invention, the dispersant is fatty alcohol polyoxyethylene ether.

[0022] In some embodiments of the present invention, the initiator is azobisisobutyronitrile or dimethyl azobisisobutyrate.

[0023] In some embodiments of the present invention, the coupling agent is silane coupling agent KH550 or KH560.

[0024] In some embodiments of the present invention, the solvent is toluene or ethyl acetate.

[0025] Another aspect of the present invention further provides a method for preparing the high-adhesion, adhesive-residue-free insulating battery tape described in the above technical solution, comprising the following steps:

[0026] S1, mixing polyacrylic acid resin, modified shellac resin, filler, initiator, coupling agent, dispersant and solvent, heating, stirring, cooling, adding curing agent, stirring to obtain acrylic pressure-sensitive adhesive for use;

[0027] S2. Apply the acrylic pressure-sensitive adhesive prepared in step S1 to the upper surface of the transparent PET substrate layer to form an acrylic pressure-sensitive adhesive layer. Then, laminate the blue PET substrate layer, the acrylic pressure-sensitive adhesive layer, and the release layer on the acrylic pressure-sensitive adhesive layer in sequence, bake, and roll up to obtain a high-bond, adhesive-residue-free insulating battery tape.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention selects polyacrylic acid resin as the main component, designs to add modified shellac resin, and prepares an acrylic pressure-sensitive adhesive in combination with a curing agent, an initiator, a coupling agent, a filler and a dispersant, and then prepares the acrylic pressure-sensitive adhesive with a transparent PET substrate layer, a blue PET substrate layer, an acrylic pressure-sensitive adhesive layer and a release layer to form a five-layer structure of the adhesive tape. Through the synergistic effect of the various components, the adhesive tape has the characteristics of high adhesion, no residual adhesive, high temperature resistance and good insulation protection, and can be widely used in the field of battery tapes.

[0030] (2) The present invention uses ethylene glycol bis(thioglycolate) as a modifier to modify the natural resin shellac resin, thereby improving the storage stability, toughness and mechanical properties of the shellac resin, thereby making the adhesive tape have the advantages of high temperature resistance, high adhesion and no residual glue. DETAILED DESCRIPTION

[0031] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0032] In the following examples and comparative examples, except for the modified shellac resin, the remaining compound monomers and related reagents used can be purchased from the market. Among them, the polyacrylic acid resin was purchased from Hubei Dali Chemical Co., Ltd.; the shellac resin is purple shellac resin, which was purchased from the Forestry Chemical Plant of Shuangjiang Lahu, Wa, Bulang and Dai Autonomous County.

[0033] Preparation Example 1

[0034] The synthetic method of modified shellac resin A comprises the following steps:

[0035] 100 g of shellac resin, 5 g of ethylene glycol bis(thioglycolate), 2 g of azobisisobutyronitrile and 200 ml of anhydrous ethanol were mixed, nitrogen was introduced for 30 min, stirred at 65° C. for 36 h, rotary evaporated, and dried at 30° C. to constant weight to obtain modified shellac resin A.

[0036] Preparation Example 2

[0037] The specific implementation of modified shellac resin B is the same as that of modified shellac resin A, except that the mass of ethylene glycol bis(thioglycolate) is replaced with 3 g.

[0038] Preparation Example 3

[0039] The specific implementation of modified shellac resin C is the same as that of modified shellac resin A, except that the mass of ethylene glycol bis(thioglycolate) is replaced with 7 g.

[0040] Example 1

[0041] A high-bonding, adhesive-residue-free insulating battery tape, comprising, from bottom to top, a transparent PET substrate layer, an acrylic pressure-sensitive adhesive layer, a blue PET substrate layer, an acrylic pressure-sensitive adhesive layer, and a release layer;

[0042] The acrylic pressure-sensitive adhesive layer is prepared by the following raw materials, calculated by weight: 90 parts of polyacrylic resin, 2.5 parts of toluene diisocyanate, 15 parts of modified shellac resin A, 6 parts of nano-silica, 2.5 parts of dimethyl azobisisobutyrate, 2 parts of silane coupling agent KH550, 2 parts of fatty alcohol polyoxyethylene ether, and 65 parts of ethyl acetate;

[0043] The release layer is a PET release layer.

[0044] The preparation method of the high-adhesion and adhesive-residue-free insulating battery tape in this embodiment includes the following steps:

[0045] S1. Mix polyacrylic acid resin, modified shellac resin A, nano-silica, dimethyl azobisisobutyrate, silane coupling agent KH550, fatty alcohol polyoxyethylene ether and ethyl acetate, heat to 70° C., stir for 30 minutes, cool to room temperature, add toluene diisocyanate, and stir for 30 minutes to obtain an acrylic pressure-sensitive adhesive for use;

[0046] S2. Apply the acrylic pressure-sensitive adhesive of step S1 on the upper surface of a transparent PET substrate layer with a thickness of 0.030 mm to form an acrylic pressure-sensitive adhesive layer with a thickness of 0.028 mm. Then, laminate a blue PET substrate layer with a thickness of 0.025 mm, an acrylic pressure-sensitive adhesive layer with a thickness of 0.027 mm, and a release layer with a thickness of 0.025 mm on the acrylic pressure-sensitive adhesive layer in sequence. Bake at 60° C. for 4 h, and roll up to obtain a high-bond, adhesive-residue-free insulating battery tape.

[0047] Example 2

[0048] A high-bonding, adhesive-residue-free insulating battery tape, comprising, from bottom to top, a transparent PET substrate layer, an acrylic pressure-sensitive adhesive layer, a blue PET substrate layer, an acrylic pressure-sensitive adhesive layer, and a release layer;

[0049] The acrylic pressure-sensitive adhesive layer is prepared by the following raw materials, calculated by weight: 80 parts of polyacrylic resin, 1 part of toluene diisocyanate, 10 parts of modified shellac resin A, 4 parts of nano-aluminum oxide, 1 part of azobisisobutyronitrile, 0.5 parts of silane coupling agent KH560, 1 part of fatty alcohol polyoxyethylene ether, and 55 parts of toluene;

[0050] The release layer is a PET release layer.

[0051] The preparation method of the high-adhesion and adhesive-residue-free insulating battery tape in this embodiment includes the following steps:

[0052] S1. Mix polyacrylic acid resin, modified shellac resin A, nano-aluminum oxide, azobisisobutyronitrile, silane coupling agent KH560, fatty alcohol polyoxyethylene ether and toluene, heat to 65° C., stir for 30 minutes, cool to room temperature, add toluene diisocyanate, and stir for 30 minutes to obtain an acrylic pressure-sensitive adhesive for use;

[0053] S2. Apply the acrylic pressure-sensitive adhesive of step S1 on the upper surface of a transparent PET substrate layer with a thickness of 0.030 mm to form an acrylic pressure-sensitive adhesive layer with a thickness of 0.028 mm. Then, laminate a blue PET substrate layer with a thickness of 0.025 mm, an acrylic pressure-sensitive adhesive layer with a thickness of 0.027 mm, and a release layer with a thickness of 0.025 mm on the acrylic pressure-sensitive adhesive layer in sequence. Bake at 60° C. for 4 h, and roll up to obtain a high-bond, adhesive-residue-free insulating battery tape.

[0054] Example 3

[0055] A high-bonding, adhesive-residue-free insulating battery tape, comprising, from bottom to top, a transparent PET substrate layer, an acrylic pressure-sensitive adhesive layer, a blue PET substrate layer, an acrylic pressure-sensitive adhesive layer, and a release layer;

[0056] The acrylic pressure-sensitive adhesive layer is prepared from the following raw materials, calculated by weight: 100 parts of polyacrylic resin, 4 parts of toluene diisocyanate, 20 parts of modified shellac resin A, 8 parts of boehmite, 4 parts of dimethyl azobisisobutyrate, 3.5 parts of silane coupling agent KH560, 3 parts of fatty alcohol polyoxyethylene ether, and 75 parts of ethyl acetate;

[0057] The release layer is a PET release layer.

[0058] The preparation method of the high-adhesion and adhesive-residue-free insulating battery tape in this embodiment includes the following steps:

[0059] S1. Mix polyacrylic acid resin, modified shellac resin A, boehmite, dimethyl azobisisobutyrate, silane coupling agent KH560, fatty alcohol polyoxyethylene ether, and ethyl acetate, heat to 70° C., stir for 30 minutes, cool to room temperature, add toluene diisocyanate, and stir for 30 minutes to obtain an acrylic pressure-sensitive adhesive for later use;

[0060] S2. Apply the acrylic pressure-sensitive adhesive of step S1 on the upper surface of a transparent PET substrate layer with a thickness of 0.030 mm to form an acrylic pressure-sensitive adhesive layer with a thickness of 0.028 mm. Then, laminate a blue PET substrate layer with a thickness of 0.025 mm, an acrylic pressure-sensitive adhesive layer with a thickness of 0.027 mm, and a release layer with a thickness of 0.025 mm on the acrylic pressure-sensitive adhesive layer in sequence. Bake at 60° C. for 4 h, and roll up to obtain a high-bond, adhesive-residue-free insulating battery tape.

[0061] Example 4

[0062] This embodiment provides a high-adhesion, adhesive-residue-free insulating battery tape and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that the modified shellac resin A is replaced by an equal amount of modified shellac resin B.

[0063] Example 5

[0064] This embodiment provides a high-adhesion, adhesive-residue-free insulating battery tape and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that the modified shellac resin A is replaced by an equal amount of modified shellac resin C.

[0065] Comparative Example 1

[0066] This comparative example provides a high-adhesion, adhesive-residue-free insulating battery tape and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that an equal amount of shellac resin is used to replace the modified shellac resin A.

[0067] Performance Testing

[0068] The performance of the high-bonding, adhesive-residue-free insulating battery tapes of Examples 1-5 and Comparative Example 1 was tested, and the test results are shown in Table 1.

[0069] (1) Adhesion performance

[0070] The adhesive strength of the tape is determined by testing its initial tack, peel strength, and lasting tack.

[0071] 1) Initial tack: According to the test method of FINAT FTM9 of the Global Association for Non-Drying Labels and Related Products;

[0072] 2) Peel Strength: Place the tape in a constant temperature oven at 100°C for 80 hours. Then, according to GB / T2792-2014, apply a standard tape (25 mm wide, 100 mm long) to a stainless steel plate cleaned with alcohol. Press back and forth with a 2 kg roller. Leave at room temperature for 24 hours. Test the tape using a peel strength tester. Measure the tape three or more times, and calculate the average value.

[0073] 3) Adhesion retention: Place the tape in a constant temperature box at 100°C for 80 hours. Then, according to the standard GB / T4851-2014, stick the standard tape (25mm wide, 100mm long) on ​​the stainless steel plate, align the upper end with the standard line, cut off the excess part of the lower end, press back and forth three times with a 2kg roller, and place it at room temperature for 30 minutes. Hang the stainless steel plate with the sample vertically on the test frame and keep it still. Hang a 500g weight below. The time it takes for the tape to fall represents the adhesion of the pressure-sensitive adhesive. The greater the adhesion, the better the adhesion.

[0074] (2) Removability

[0075] The test plate is a stainless steel plate (forming a sandwich structure with the tape); the tape size is 12mm×110mm, the pressing condition is 0.25MPa, the pressure is maintained for 10s, the immersion time is 24h, the test environment is 23±1℃, 50±5%RH, and the tape is stretched and removed at a 30° angle and a removal rate of 300mm / min. The removal process records whether the tape breaks and whether there is any residual adhesive on the plate.

[0076] Table 1

[0077]

[0078]

[0079] As shown in Table 1, the tapes in Examples 1-3 of the present invention exhibit excellent initial tack and sustained adhesion, high peel strength, high temperature resistance, and good removability. Specifically, Examples 4-5 varied the ratio of ethylene glycol bis(thioglycolate) to shellac resin in the modified shellac resin, resulting in decreased storage stability, toughness, and mechanical properties. This reduced the tape's initial tack, high-temperature sustained adhesion, and peel strength, and also impacted removability, with slight adhesive residue present. Comparative Example 1, in which shellac resin was substituted for modified shellac resin A in equal amounts, exhibited poor adhesive and removability.

[0080] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-bonding, no-residue adhesive insulating battery tape, characterized in that: The adhesive tape comprises, from bottom to top, a transparent PET substrate layer, an acrylic pressure-sensitive adhesive layer, a blue PET substrate layer, an acrylic pressure-sensitive adhesive layer and a release layer; The acrylic pressure-sensitive adhesive layer is prepared by the following raw materials, calculated by weight: 80-100 parts of polyacrylic resin, 1-4 parts of curing agent, 10-20 parts of modified shellac resin, 4-8 parts of filler, 1-4 parts of initiator, 0.5-3.5 parts of coupling agent, 1-3 parts of dispersant, and 55-75 parts of solvent; The release layer is a PET release layer.

2. The high-bonding, residue-free insulating battery tape according to claim 1, characterized in that: The thickness of the transparent PET substrate layer is 0.028-0.032 mm, the thickness of the acrylic pressure-sensitive adhesive layer is 0.026-0.030 mm, the thickness of the blue PET substrate layer is 0.023-0.027 mm, and the thickness of the release layer is 0.023-0.027 mm.

3. The high-bonding, residue-free insulating battery tape according to claim 1, characterized in that: The curing agent is an isocyanate curing agent.

4. The high-bonding, adhesive-residue-free insulating battery tape according to claim 1, characterized in that: The preparation method of the modified shellac resin comprises the following steps: Mix shellac resin, ethylene glycol bis(thioglycolate), azobisisobutyronitrile and anhydrous ethanol, introduce inert gas, stir at 60-70° C. for 35-37 hours, rotary evaporate and dry to obtain modified shellac resin.

5. The high-bonding, adhesive-residue-free insulating battery tape according to claim 4, characterized in that: The mass ratio of the shellac resin to ethylene glycol bis(thioglycolate) is 1:(0.04-0.06).

6. The high-bonding, adhesive-residue-free insulating battery tape according to claim 1, characterized in that: The filler is any one of boehmite, nano silicon dioxide and nano aluminum oxide.

7. The high-bonding, residue-free insulating battery tape according to claim 1, characterized in that: The dispersant is fatty alcohol polyoxyethylene ether.

8. The high-bonding, adhesive-residue-free insulating battery tape according to claim 1, characterized in that: The initiator is azobisisobutyronitrile or dimethyl azobisisobutyrate.

9. The high-bonding, residue-free insulating battery tape according to claim 1, characterized in that: The solvent is toluene or ethyl acetate.

10. A method for preparing the high-adhesion, adhesive-residue-free insulating battery tape according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, mixing polyacrylic acid resin, modified shellac resin, filler, initiator, coupling agent, dispersant and solvent, heating, stirring, cooling, adding curing agent, stirring to obtain acrylic pressure-sensitive adhesive for use; S2. Apply the acrylic pressure-sensitive adhesive prepared in step S1 to the upper surface of the transparent PET substrate layer to form an acrylic pressure-sensitive adhesive layer. Then, laminate the blue PET substrate layer, the acrylic pressure-sensitive adhesive layer, and the release layer on the acrylic pressure-sensitive adhesive layer in sequence, bake, and roll up to obtain a high-bond, adhesive-residue-free insulating battery tape.

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