High expansion ratio expansion tape and preparation method thereof

Abstract

The invention discloses a high expansion ratio expansion tape and a preparation method thereof, wherein the expansion tape comprises a first substrate layer, a first expansion adhesive layer, a second substrate layer and a second expansion adhesive layer which are sequentially stacked. The high expansion ratio expansion tape of the invention adopts a secondary expansion structure, so that the tape can expand under heat and swell in an electrolyte, and exert the expansion effect to the maximum extent; the heat-expandable microspheres added in the first expansion adhesive layer are polymer particles with a core-shell structure, and when the microspheres are heated, the internal foaming agent vaporizes or decomposes to generate pressure, and at the same time the shell softens and expands, and the thermoplastic polymer shell and the gas pressure generated by the high temperature are balanced with each other, and after cooling, the polymer shell does not shrink, and the expansion effect is achieved; the second expansion adhesive layer produces an obvious swelling effect in the solvent environment of the electrolyte to achieve the effect of secondary expansion.

Description

Technical Field

[0001] The invention relates to the field of expansion tape materials, and in particular to an expansion tape with a high expansion ratio and a preparation method thereof. Background Art

[0002] Usually, there is a certain gap between the bare cell and the shell of a cylindrical or square lithium-ion battery. During the use of the battery, there is a risk that the bare cell and the shell will shake relative to each other, causing the cell to fail. Since a certain gap must be left when the bare cell enters the shell, only post-expansion expansion tape can be used to fill the gap. Among the common small cylindrical cells, expansion tapes based on oriented polystyrene (OPS) are the most widely used. This type of expansion tape is based on the swelling of OPS in the electrolyte. In actual use, this type of tape has problems such as easy dissolution, low strength, and low expansion ratio.

[0003] The purpose of using expansion tape is to connect the bare cell and the shell together, so as to avoid relative movement between the bare cell and the shell when the battery encounters vibration, and solve the problems such as short circuit of single cell and desoldering of the tab caused by vibration, thereby ensuring and extending the safety and service life of the battery.

[0004] Patent CN111995957A discloses a high expansion ratio oriented polystyrene expansion tape and its preparation method, wherein the high expansion ratio oriented polystyrene expansion tape and its preparation method are composited by a single-sided release oriented polystyrene film substrate and an acrylate adhesive layer. The characteristic is that the oriented polystyrene film substrate is composited by a single-sided release oriented polystyrene film substrate and an acrylate adhesive layer. The high expansion ratio oriented polystyrene expansion tape is characterized in that the oriented polystyrene film substrate is extruded by a general-purpose polystyrene resin and then stretched 3 to 5 times in the transverse direction. The polystyrene film used in this patent has problems such as poor thermal stability and easy solubility in electrolyte, which limits its application scope to a certain extent.

[0005] Patent CN213037690U discloses a high expansion tape that prevents battery internal parts from vibrating and prolongs battery life, and relates to the field of battery protection technology. It includes a tape body, and the tape body includes a substrate layer, an upper high temperature expansion adhesive layer, an upper low temperature expansion adhesive layer, an upper pressure-sensitive adhesive layer, an upper release film layer, a lower high temperature expansion adhesive layer, a lower low temperature expansion adhesive layer, a lower pressure-sensitive adhesive layer and a lower release film layer. The upper surface of the substrate layer is fixedly attached with an upper high temperature expansion adhesive layer, the upper surface of the upper high temperature expansion adhesive layer is fixedly attached with an upper low temperature expansion adhesive layer, and the upper surface of the upper low temperature expansion adhesive layer is fixedly attached with an upper pressure-sensitive adhesive layer. This method improves the mechanical and temperature resistance properties of polystyrene through multi-layer composite of complex structures, but the preparation process of this scheme is too complicated, which limits its application. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an expansion tape with a high expansion ratio and a preparation method thereof in view of the deficiencies in the above-mentioned prior art.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a high expansion ratio expansion tape, which comprises a first substrate layer, a first expansion adhesive layer, a second substrate layer and a second expansion adhesive layer which are stacked in sequence;

[0008] The first substrate layer and the second substrate layer are both PP / PE copolymer microporous films, the first expansion adhesive layer is a heat expansion adhesive layer, the second expansion adhesive layer is a solvent expansion adhesive layer, and the first expansion adhesive layer is prepared by the following steps:

[0009] 1-1) dissolving an acrylic resin in a solvent to obtain an acrylic resin solution 1;

[0010] 1-2) adding toluene diisocyanate, a curing agent, and heat-expandable microspheres to the acrylic resin solution 1 obtained in step 1-1) in sequence under stirring, and stirring and dispersing them into a colloid 1;

[0011] 1-3) dissolving bisphenol A epoxy resin in a solvent to obtain an epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring, and standing;

[0012] 1-4) adding a defoaming agent to the product obtained in step 1-3), stirring, filtering, and discarding the filter residue to obtain a first expansion glue, and the first expansion glue is coated and dried to obtain the first expansion glue layer.

[0013] Preferably, the first expansion adhesive layer is prepared by the following steps:

[0014] 1-1) dissolving 15-60 g of acrylic resin in 5-20 g of solvent to obtain acrylic resin solution 1;

[0015] 1-2) adding 0.15-0.6 g toluene diisocyanate, 1.5-6 g curing agent, and 1-4 g heat-expandable microspheres to the acrylic resin solution 1 obtained in step 1-1) in sequence under stirring, stirring and dispersing for 15-60 min to obtain a colloid 1;

[0016] 1-3) dissolving 0.05-0.3 g of bisphenol A epoxy resin in a solvent to obtain an epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring for 15-60 min, and standing for 0.5-2 h;

[0017] 1-4) adding a defoaming agent to the product obtained in step 1-3), stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a first expansion glue, and the first expansion glue is coated and dried to obtain the first expansion glue layer.

[0018] Preferably, the heat-expandable microspheres are polymethacrylimide heat-expandable microspheres.

[0019] Preferably, the heat-expandable microspheres are prepared by Pickering emulsion suspension polymerization of an alkane foaming agent wrapped by an unsaturated olefin monomer, and the unsaturated olefin monomer includes the following components in percentage by mass: 70% acrylonitrile, 20% methacrylic acid, 6% acrylamide, and 4% acrylate.

[0020] Preferably, the second expansion adhesive layer is prepared by the following steps:

[0021] 2-1) dissolving an acrylic resin in a solvent to obtain an acrylic resin solution 2;

[0022] 2-2) adding toluene diisocyanate, terpene resin and curing agent to the acrylic resin solution 2 in sequence under stirring, stirring and dispersing, to obtain colloid 2;

[0023] 2-3) dissolving bisphenol A epoxy resin in a solvent to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) into the epoxy resin solution 2 under stirring, stirring, and standing;

[0024] 2-4) adding a defoaming agent to the product obtained in step 2-3), stirring, filtering, and discarding the filter residue to obtain a second expansion glue, and the second expansion glue is coated and dried to obtain the second expansion glue layer.

[0025] Preferably, the second expansion adhesive layer is prepared by the following steps:

[0026] 2-1) dissolving 15-60 g of acrylic resin in 5-20 g of solvent to obtain acrylic resin solution 2;

[0027] 2-2) 0.15-0.6 g of toluene diisocyanate, 2-9 g of terpene resin, and 1.5-6 g of curing agent are sequentially added to the acrylic resin solution 2 under stirring conditions, and stirred and dispersed for 15-60 minutes to obtain colloid 2;

[0028] 2-3) dissolving 0.05-0.3 g of bisphenol A epoxy resin in a solvent to obtain an epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring for 15-60 min, and standing for 0.5-2 h;

[0029] 2-4) adding a defoaming agent to the product obtained in step 2-3), stirring, filtering with a 200-mesh filter, discarding the filter residue to obtain a second expansion glue, and coating and drying the second expansion glue to obtain the second expansion glue layer.

[0030] Preferably, the PP / PE copolymer microporous membrane is prepared by melt blending linear polypropylene and long-chain branched polyethylene in a mass ratio of 9:1, extruding and casting, and then stretching and heat-setting.

[0031] Preferably, the acrylic resin is a long-chain thermosetting acrylic resin, the solvent is ethyl acetate, the curing agent is an aziridine curing agent, and the defoaming agent is isooctyl alcohol.

[0032] Preferably, the thickness of the first expansion adhesive layer and the second expansion adhesive layer are both 50 μm-150 μm.

[0033] The present invention also provides a method for preparing the high expansion ratio expansion tape as described above, comprising the following steps:

[0034] S1, corona-treating the bottom surface of the first substrate layer, coating the first expansion glue on the corona-treated surface, and drying and curing to form a first expansion glue layer;

[0035] S2, laminating the second substrate layer on the adhesive surface of the first expansion adhesive layer;

[0036] S3, after corona treatment, coating the second expansion glue on the bottom surface of the second substrate layer, drying and curing to form a second expansion glue layer, and finally attaching a release film to the bottom surface of the second expansion glue layer, and rolling it up to obtain the high expansion ratio expansion tape.

[0037] The beneficial effects of the present invention are:

[0038] (1) The high expansion ratio expandable tape of the present invention adopts a secondary expansion structure, so that the tape can expand under heat and swell in the electrolyte, thereby maximizing the expansion effect; wherein, the heat-expandable microspheres added to the first expandable adhesive layer are polymer particles with a core-shell structure. When the microspheres are heated, the internal foaming agent vaporizes or decomposes to generate pressure, and at the same time the shell softens and expands. The thermoplastic polymer shell and the gas pressure generated by the high temperature are balanced with each other. After cooling, the polymer shell does not shrink, thereby achieving the expansion effect. The second expandable adhesive layer forms a structural system with a high degree of cross-linking due to the selection of long-chain acrylic resin and the combination of the curing system. Therefore, in the solvent environment of the electrolyte, it produces a significant swelling effect and achieves the effect of secondary expansion.

[0039] (2) The present invention uses a PP / PE copolymer microporous membrane as a substrate, and its microporous structure can provide an ion transmission channel. The selection of the substrate can not only meet the material requirements for long-term use of the electrolyte, but also ensure that the present invention minimizes the impact on ion conduction;

[0040] (3) The composite multi-layer structure of the high expansion ratio expansion tape of the present invention can achieve gradient adaptation of thickness, thereby being able to meet the use requirements in different scenarios and protecting the expansion functional adhesive layer to the maximum extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic structural diagram of the high expansion ratio expansion tape of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0043] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0044] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0045] Reference Figure 1 The present invention provides a high expansion ratio expansion tape, which comprises a first base material layer, a first expansion adhesive layer, a second base material layer and a second expansion adhesive layer stacked in sequence from top to bottom;

[0046] In the present invention, both the first substrate layer and the second substrate layer are PP / PE copolymer microporous membranes. In a preferred embodiment, the PP / PE copolymer microporous membrane is prepared by melt blending linear polypropylene (PP) and long-chain branched polyethylene (PE) at a mass ratio of 9:1, extruding and casting, and stretching and heat setting. The PP / PE copolymer microporous membrane can provide strength support for the expansion tape, and the material can also avoid reaction with the electrolyte and does not hinder ion conduction.

[0047] In the present invention, the first expansion adhesive layer is a heat expansion adhesive layer. In a preferred embodiment, the first expansion adhesive layer is prepared by the following steps:

[0048] 1-1) dissolving 15-60 g of acrylic resin in 5-20 g of solvent to obtain acrylic resin solution 1;

[0049] 1-2) 0.15-0.6 g of toluene diisocyanate, 1.5-6 g of curing agent, and 1-4 g of heat-expandable microspheres are sequentially added to the acrylic resin solution 1 obtained in step 1-1) under stirring conditions, and stirred and dispersed for 15-60 minutes to obtain a colloid 1;

[0050] 1-3) dissolving 0.05-0.3 g of bisphenol A epoxy resin in a solvent to obtain an epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring for 15-60 min, and standing for 0.5-2 h;

[0051] 1-4) adding a defoaming agent to the product obtained in step 1-3), stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a first expansion glue. The first expansion glue is coated and dried to obtain a first expansion glue layer.

[0052] The heat-expandable microspheres are polymethacrylimide heat-expandable microspheres. In a preferred embodiment, the heat-expandable microspheres are made of unsaturated olefin monomers wrapped with alkane foaming agents through Pickering emulsion suspension polymerization, and the unsaturated olefin monomers include the following components in mass percentage: 70% acrylonitrile, 20% methacrylic acid, 6% acrylamide, and 4% acrylate.

[0053] In the present invention, the second swelling adhesive layer is a solvent swelling adhesive layer, which is prepared by the following steps:

[0054] 2-1) dissolving 15-60 g of acrylic resin in 5-20 g of solvent to obtain acrylic resin solution 2;

[0055] 2-2) 0.15-0.6 g of toluene diisocyanate, 2-9 g of terpene resin, and 1.5-6 g of curing agent are sequentially added to the acrylic resin solution 2 under stirring conditions, and stirred and dispersed for 15-60 minutes to obtain colloid 2;

[0056] 2-3) dissolving 0.05-0.3 g of bisphenol A epoxy resin in a solvent to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring for 15-60 min, and standing for 0.5-2 h;

[0057] 2-4) adding a defoaming agent to the product obtained in step 2-3), stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a second expansion glue. The second expansion glue is coated and dried to obtain a second expansion glue layer.

[0058] In a preferred embodiment, the acrylic resin used in the first expansion adhesive layer and the second expansion adhesive layer is a long-chain thermosetting acrylic resin, the solvent is ethyl acetate, the curing agent is aziridine curing agent, and the defoaming agent is isooctyl alcohol.

[0059] In a preferred embodiment, the thickness of the first expansion adhesive layer and the second expansion adhesive layer are both 50μm-150μm. The first expansion adhesive layer can produce an expansion effect of 2-3 times the thickness of the tape under the heat of 90℃-120℃, and the second expansion adhesive layer can produce an expansion effect of 2-3 times the thickness of the tape after being immersed in a room temperature electrolyte for 12 hours; thus, the high expansion ratio expansion tape of the present invention can produce an expansion effect of 4-6 times the thickness of the tape after undergoing thermal expansion and electrolyte expansion.

[0060] The present invention also provides a method for preparing the above high expansion ratio expansion tape, comprising the following steps:

[0061] S1, corona-treating the bottom surface of the first substrate layer, coating the first expansion glue on the corona-treated surface, and drying and curing to form a first expansion glue layer;

[0062] S2, laminating the second substrate layer on the adhesive surface of the first expansion adhesive layer;

[0063] S3, after corona treatment, coating the second expansion glue on the bottom surface of the second substrate layer, drying and curing to form a second expansion glue layer, finally attaching a release film to the bottom surface of the second expansion glue layer, and rolling it up to obtain a high expansion ratio expansion tape.

[0064] Detailed examples and comparative examples are provided below to further illustrate the present invention.

[0065] Example 1

[0066] A high expansion ratio expansion tape is prepared by the following steps:

[0067] S1, corona-treating the bottom surface of the first substrate layer, coating the first expansion glue on the corona-treated surface, and drying and curing to form a first expansion glue layer;

[0068] S2, laminating the second substrate layer on the adhesive surface of the first expansion adhesive layer;

[0069] S3. After corona treatment, the second expansion glue is coated on the bottom surface of the second substrate layer, and dried and solidified to form a second expansion glue layer. Finally, a release film is attached to the bottom surface of the second expansion glue layer and rolled up to obtain a high expansion ratio expansion tape with a thickness of 300 μm.

[0070] The first expansion adhesive layer is prepared by the following steps:

[0071] 1-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 1;

[0072] 1-2) 0.3 g of toluene diisocyanate, 3 g of aziridine curing agent, and 2 g of heat-expandable microspheres were sequentially added to the acrylic resin solution 1 obtained in step 1-1) under stirring conditions, and stirred and dispersed for 30 minutes to obtain a colloid 1;

[0073] 1-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring for 30 min, and standing for 1 h;

[0074] 1-4) Add 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 1-3) to improve coating performance, stir, filter with a 200-mesh filter, discard the filter residue, and obtain a first expansion glue. The first expansion glue can be coated and dried to obtain a first expansion glue layer.

[0075] The second swellable adhesive layer is a solvent swellable adhesive layer prepared by the following steps:

[0076] 2-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 2;

[0077] 2-2) 0.3 g of toluene diisocyanate, 4.5 g of terpene resin, and 3 g of curing agent were sequentially added to the acrylic resin solution 2 under stirring conditions, and stirred and dispersed for 30 minutes to obtain colloid 2;

[0078] 2-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring for 30 min, and standing for 1 h;

[0079] 2-4) adding 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 2-3) to improve coating performance, stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a second expansion glue. The second expansion glue is coated and dried to obtain a second expansion glue layer.

[0080] The heat-expandable microspheres are prepared by Pickering emulsion suspension polymerization of unsaturated olefin monomers wrapped with alkane foaming agents, and the unsaturated olefin monomers include the following components in mass percentage: acrylonitrile 70%, methacrylic acid 20%, acrylamide 6%, and acrylate 4%. The specific preparation method refers to patent CN110698721A, a polymethacrylimide heat-expandable microsphere and its preparation method.

[0081] Example 2

[0082] The difference between this embodiment and embodiment 1 is only in the preparation method of the first expansion adhesive layer and the second expansion adhesive layer. Only the differences are listed below.

[0083] The first expansion adhesive layer is prepared by the following steps:

[0084] 1-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 1;

[0085] 1-2) 0.3 g of toluene diisocyanate, 3 g of aziridine curing agent, and 3 g of heat-expandable microspheres were sequentially added to the acrylic resin solution 1 obtained in step 1-1) under stirring conditions, and stirred and dispersed for 30 minutes to obtain a colloid 1;

[0086] 1-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring for 30 min, and standing for 1 h;

[0087] 1-4) Add 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 1-3) to improve coating performance, stir, filter with a 200-mesh filter, discard the filter residue, and obtain a first expansion glue. The first expansion glue can be coated and dried to obtain a first expansion glue layer.

[0088] The second swellable adhesive layer is a solvent swellable adhesive layer prepared by the following steps:

[0089] 2-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 2;

[0090] 2-2) 0.3 g of toluene diisocyanate, 4.5 g of terpene resin, and 4 g of curing agent were sequentially added to the acrylic resin solution 2 under stirring conditions, and stirred and dispersed for 30 minutes to obtain colloid 2;

[0091] 2-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring for 30 min, and standing for 1 h;

[0092] 2-4) adding 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 2-3) to improve coating performance, stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a second expansion glue. The second expansion glue is coated and dried to obtain a second expansion glue layer.

[0093] Example 3

[0094] The difference between this embodiment and embodiment 1 is only in the preparation method of the first expansion adhesive layer and the second expansion adhesive layer. Only the differences are listed below.

[0095] The first expansion adhesive layer is prepared by the following steps:

[0096] 1-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 1;

[0097] 1-2) 0.3 g of toluene diisocyanate, 3 g of aziridine curing agent, and 4 g of heat-expandable microspheres were sequentially added to the acrylic resin solution 1 obtained in step 1-1) under stirring conditions, and stirred and dispersed for 30 minutes to obtain a colloid 1;

[0098] 1-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring for 30 min, and standing for 1 h;

[0099] 1-4) Add 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 1-3) to improve coating performance, stir, filter with a 200-mesh filter, discard the filter residue, and obtain a first expansion glue. The first expansion glue can be coated and dried to obtain a first expansion glue layer.

[0100] The second swellable adhesive layer is a solvent swellable adhesive layer prepared by the following steps:

[0101] 2-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 2;

[0102] 2-2) 0.3 g of toluene diisocyanate, 4.5 g of terpene resin, and 5 g of curing agent were sequentially added to the acrylic resin solution 2 under stirring conditions, and stirred and dispersed for 30 minutes to obtain colloid 2;

[0103] 2-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring for 30 min, and standing for 1 h;

[0104] 2-4) adding 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 2-3) to improve coating performance, stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a second expansion glue. The second expansion glue is coated and dried to obtain a second expansion glue layer.

[0105] Comparative Example 1

[0106] The difference between this example and Example 2 is only in the preparation method of the first expansion adhesive layer and the second expansion adhesive layer. Only the differences are listed below.

[0107] The first expansion adhesive layer is prepared by the following steps:

[0108] 1-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 1;

[0109] 1-2) 0.3 g of toluene diisocyanate and 3 g of aziridine curing agent were sequentially added to the acrylic resin solution 1 obtained in step 1-1) under stirring conditions, and stirred and dispersed for 30 minutes to obtain a colloid 1;

[0110] 1-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring for 30 min, and standing for 1 h;

[0111] 1-4) Add 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 1-3) to improve coating performance, stir, filter with a 200-mesh filter, discard the filter residue, and obtain a first expansion glue. The first expansion glue can be coated and dried to obtain a first expansion glue layer.

[0112] The second swellable adhesive layer is a solvent swellable adhesive layer prepared by the following steps:

[0113] 2-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 2;

[0114] 2-2) 0.3 g of toluene diisocyanate, 4.5 g of terpene resin, and 4 g of curing agent were sequentially added to the acrylic resin solution 2 under stirring conditions, and stirred and dispersed for 30 minutes to obtain colloid 2;

[0115] 2-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring for 30 min, and standing for 1 h;

[0116] 2-4) adding 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 2-3) to improve coating performance, stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a second expansion glue. The second expansion glue is coated and dried to obtain a second expansion glue layer.

[0117] Comparative Example 2

[0118] The difference between this example and Example 2 is that the materials of the first substrate layer and the second substrate layer are different. In this example, the first substrate layer and the second substrate layer are both made of PET material.

[0119] Comparative Example 3

[0120] The difference between this example and Example 1 is only in the preparation method of the first expansion adhesive layer and the second expansion adhesive layer. Only the differences are listed below.

[0121] The first expansion adhesive layer is prepared by the following steps:

[0122] 1-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 1;

[0123] 1-2) 0.3 g of toluene diisocyanate and 3 g of heat-expandable microspheres were sequentially added to the acrylic resin solution 1 obtained in step 1-1) under stirring conditions, and stirred and dispersed for 30 minutes to obtain a colloid 1;

[0124] 1-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring for 30 min, and standing for 1 h;

[0125] 1-4) Add 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 1-3) to improve coating performance, stir, filter with a 200-mesh filter, discard the filter residue, and obtain a first expansion glue. The first expansion glue can be coated and dried to obtain a first expansion glue layer.

[0126] The second swellable adhesive layer is a solvent swellable adhesive layer prepared by the following steps:

[0127] 2-1) dissolving 30 g of long-chain thermosetting acrylic resin (BS9417B) in 10 g of ethyl acetate to obtain acrylic resin solution 2;

[0128] 2-2) 0.3 g of toluene diisocyanate and 4.5 g of terpene resin were added to the acrylic resin solution 2 in sequence under stirring conditions, and the mixture was stirred and dispersed for 30 minutes to obtain colloid 2;

[0129] 2-3) dissolving 0.15 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring for 30 min, and standing for 1 h;

[0130] 2-4) adding 0.3 g of isooctyl alcohol as a defoaming agent to the product obtained in step 2-3) to improve coating performance, stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a second expansion glue. The second expansion glue is coated and dried to obtain a second expansion glue layer.

[0131] The expansion tapes prepared in Examples 1-3 and Comparative Examples 1-3 were baked in a high temperature oven at 120°C for 4 hours, and then immersed in an electrolyte (solvent EC:DEC:DMC=1:1:3, 5wt% lithium hexafluorophosphate was added to the above solvent system to obtain an electrolyte) at room temperature for 12 hours, and then performance tests were performed. The test results are shown in Table 1 below:

[0132] Table 1

[0133] Peel force (gf / inch) Foaming ratio (%) Shrinkage rate (%) Compressive strength(MPa) Appearance Embodiment 1 350 550 1 1.2 whole Embodiment 2 330 600 1 1.2 whole Embodiment 3 300 660 1 1.2 whole Comparative Example 1 325 300 1 1.2 whole Comparative Example 2 260 450 1 1.3 whole Comparative Example 3 280 400 1 1.0 Edge Dissolve

[0134] The thickness of the expansion tape prepared in the above examples and comparative examples is 300 μm. The thickness of Examples 1-3 can reach about 1100 μm after baking for 4 hours, and can reach about 2000 μm after being immersed in the electrolyte at room temperature for 12 hours. The highest expansion ratio of the expansion tape is 660%, and the product shrinkage is small, the appearance is complete, and the compressive strength can reach 1.2 MPa. The expansion ratio and other properties of Comparative Examples 1-3 are significantly lower than those of Examples 1-3.

[0135] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A high expansion ratio expansion tape, characterized in that: It comprises a first base material layer, a first expansion adhesive layer, a second base material layer and a second expansion adhesive layer which are stacked in sequence; The first substrate layer and the second substrate layer are both PP / PE copolymer microporous films, the first expansion adhesive layer is a heat expansion adhesive layer, the second expansion adhesive layer is a solvent expansion adhesive layer, and the first expansion adhesive layer is prepared by the following steps: 1-1) dissolving an acrylic resin in a solvent to obtain an acrylic resin solution 1; 1-2) adding toluene diisocyanate, a curing agent, and heat-expandable microspheres to the acrylic resin solution 1 obtained in step 1-1) in sequence under stirring, and stirring and dispersing them into a colloid 1; 1-3) dissolving bisphenol A epoxy resin in a solvent to obtain epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring, and standing; 1-4) adding a defoaming agent to the product obtained in step 1-3), stirring, filtering, and discarding the filter residue to obtain a first expansion glue, and the first expansion glue is coated and dried to obtain the first expansion glue layer; The second expansion adhesive layer is prepared by the following steps: 2-1) dissolving an acrylic resin in a solvent to obtain an acrylic resin solution 2; 2-2) adding toluene diisocyanate, terpene resin and curing agent to the acrylic resin solution 2 in sequence under stirring, stirring and dispersing, to obtain colloid 2; 2-3) dissolving bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring, and standing; 2-4) adding a defoaming agent to the product obtained in step 2-3), stirring, filtering, and discarding the filter residue to obtain a second expansion glue, and the second expansion glue is coated and dried to obtain the second expansion glue layer; The acrylic resin is a long-chain thermosetting acrylic resin.

2. The high expansion ratio expansion tape according to claim 1, characterized in that: The first expansion adhesive layer is prepared by the following steps: 1-1) dissolving 15-60 g of acrylic resin in 5-20 g of solvent to obtain acrylic resin solution 1; 1-2) 0.15-0.6 g of toluene diisocyanate, 1.5-6 g of curing agent, and 1-4 g of heat-expandable microspheres are sequentially added to the acrylic resin solution 1 obtained in step 1-1) under stirring conditions, and stirred and dispersed for 15-60 minutes to obtain a colloid 1; 1-3) dissolving 0.05-0.3 g of bisphenol A epoxy resin in a solvent to obtain an epoxy resin solution 1, adding the colloid 1 prepared in step 1-2) to the epoxy resin solution 1 under stirring, stirring for 15-60 min, and standing for 0.5-2 h; 1-4) Add a defoaming agent to the product obtained in step 1-3), stir, filter with a 200-mesh filter, discard the filter residue to obtain a first expansion glue, and apply and dry the first expansion glue to obtain the first expansion glue layer.

3. The high expansion ratio expansion tape according to claim 1, characterized in that: The heat-expandable microspheres are polymethacrylimide-type heat-expandable microspheres.

4. The high expansion ratio expansion tape according to claim 3, characterized in that: The heat-expandable microspheres are prepared by unsaturated olefin monomers encapsulating an alkane foaming agent through Pickering emulsion suspension polymerization. The unsaturated olefin monomers include the following components in percentage by weight: 70% acrylonitrile, 20% methacrylic acid, 6% acrylamide, and 4% acrylate.

5. The high expansion ratio expandable tape according to claim 1, characterized in that: The second expansion adhesive layer is prepared by the following steps: 2-1) dissolving 15-60 g of acrylic resin in 5-20 g of solvent to obtain acrylic resin solution 2; 2-2) 0.15-0.6 g of toluene diisocyanate, 2-9 g of terpene resin, and 1.5-6 g of curing agent are sequentially added to the acrylic resin solution 2 under stirring conditions, and stirred and dispersed for 15-60 minutes to obtain colloid 2; 2-3) dissolving 0.05-0.3 g of bisphenol A epoxy resin in ethyl acetate to obtain epoxy resin solution 2, adding the colloid 2 prepared in step 2-2) to the epoxy resin solution 2 under stirring, stirring for 15-60 min, and standing for 0.5-2 h; 2-4) Adding a defoaming agent to the product obtained in step 2-3), stirring, filtering with a 200-mesh filter, discarding the filter residue, and obtaining a second expansion glue. The second expansion glue is coated and dried to obtain the second expansion glue layer.

6. The high expansion ratio expansion tape according to claim 1, characterized in that: The PP / PE copolymer microporous membrane is prepared by melt blending linear polypropylene and long-chain branched polyethylene in a mass ratio of 9:1, extruding and casting, and then stretching and heat-setting.

7. The high expansion ratio expandable tape according to claim 1, characterized in that: The solvent is ethyl acetate, the curing agent is aziridine curing agent, and the defoaming agent is isooctyl alcohol.

8. The high expansion ratio expandable tape according to claim 1, characterized in that: The thickness of the first expansion adhesive layer and the second expansion adhesive layer are both 50 μm-150 μm.

9. A method for preparing a high expansion ratio expandable tape according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, corona-treating the bottom surface of the first substrate layer, coating the first expansion glue on the corona-treated surface, and drying and curing to form a first expansion glue layer; S2, laminating the second substrate layer on the adhesive surface of the first expansion adhesive layer; S3, after corona treatment, coating the second expansion glue on the bottom surface of the second substrate layer, drying and curing to form a second expansion glue layer, and finally attaching a release film to the bottom surface of the second expansion glue layer, and rolling it up to obtain the high expansion ratio expansion tape.

Images