WO2018081941A1

WO2018081941A1 - Structural adhesive tape, preparation method therefor, and method for reserving tab space in electrode plate

Info

Publication number: WO2018081941A1
Application number: PCT/CN2016/104319
Authority: WO
Inventors: 戴志芳; 龙海; 陶兴华; 张盛武
Original assignee: 宁德新能源科技有限公司
Priority date: 2016-11-02
Filing date: 2016-11-02
Publication date: 2018-05-11

Abstract

Provided in the present invention are a structural adhesive tape, a preparation method therefor, and a method for reserving a tab space in an electrode plate. The structural adhesive tape comprises: an adhesive layer, for affixing to an object to be affixed; and a substrate, located on a side of the structural adhesive tape which is far away from the object to be affixed. The adhesive layer includes a first adhesive, a first curing agent, a second adhesive, a second curing agent, and foaming agent particles which are distributed therein. The curing temperature of the first adhesive and the first curing agent is 20°C-80°C; and the curing temperature of the second adhesive and second curing agent is greater than 80°C and less than or equal to 180°C. The structural adhesive tape of the invention has extremely high viscous consistency with respect to the object to be affixed, and is easy to be mass-produced, thus solving the problem wherein the viscosity of foaming agent particles in a conventional adhesive tape fluctuates significantly after foaming. The structural adhesive tape of the present invention may improve the utilization ratio of the active material of a battery, avoid wasting the active material, while at the same time improving the energy density, quick charging and discharging performances and heat dissipation performances of a battery.

Description

Structural adhesive tape and preparation method thereof, and method for preserving polar vacancies in electrode sheets

Technical field

The invention relates to the field of adhesive tape, in particular to a structural adhesive tape and a preparation method thereof, and a method for leaving a ferrule in an electrode sheet.

Background technique

The prior art adhesive tape generally uses a PET substrate and an acrylate-based pressure-sensitive adhesive plus a foaming agent particle to effect foaming to peel off from the current collector to reserve a crater on the current collector. Referring to FIGS. 7A and 7B, when the residual solvent amount of the adhesive layer 2' is excessively large (>10%), the blowing agent particles 21' are completely coated in the adhesive in the adhesive layer 2'. Even if the foaming agent particles 21' expand after foaming, the contact area between the adhesive and the current collector cannot be effectively reduced, and the adhesive paper is difficult to be peeled off, and the polar ear vacancies cannot be reserved on the current collector. Referring to FIGS. 8A and 8B, when the amount of residual solvent of the adhesive layer 2' is relatively suitable (5% to 10%), part of the blowing agent particles 21' are placed at the interface between the adhesive and the current collector. After the foaming agent particles 21' are foamed, the contact area between the adhesive and the current collector can be effectively reduced, and the adhesive tape can be peeled off normally, but the process is demanding and the yield is low, which cannot meet the demand for mass production. Referring to FIGS. 9A and 9B, when the residual solvent amount of the adhesive layer 2' is too low (<5%), most of the blowing agent particles 21' have been exposed outside the adhesive, and the blowing agent particles 21' After foaming, the adhesive almost loses its bond with the current collector, causing the adhesive paper to become tacky and contaminate the membrane.

Since the foaming agent particles generally have a wide particle size distribution (5 μm to 30 μm), they are mixed and coated in an adhesive for drying and drying, and two failure modes are apt to occur. In the first type, the adhesive layer is too thick, and the foaming expansion of the foaming agent particles cannot effectively reduce the contact area between the adhesive and the current collector, resulting in excessive viscosity after foaming, and cannot be peeled off from the empty foil region of the current collector. Causes a broken belt. Secondly, the adhesive layer is too thin, and the foaming agent particles are exposed outside the adhesive, which hinders the contact between the adhesive and the empty foil area of the current collector, resulting in weak viscosity after foaming, due to the foaming agent particles. When the foaming agent is not completely dried during foaming, when the foaming agent particles are weakly viscous, the adhesive tape is easily taken up by the hot air and sticks to the wet film area. After the wet film is dried, the foaming agent particles are intensively increased and cannot be normalized. Peeling can also cause broken belts.

In addition, since the thickness of the adhesive layer is usually required to be small, the precision of the conventional coating process cannot meet the requirements, and the thickness fluctuation causes a large amount of products to be scrapped.

Summary of the invention

In view of the problems in the prior art, an object of the present invention is to provide a structural adhesive tape and a method for preparing the same, and a method for preserving a vacancy of a tab on an electrode sheet, wherein the structural adhesive sheet is in conformity with the object to be pasted. High and easy to carry out Batch production has solved the problem of serious viscosity fluctuation after foaming agent particles in conventional adhesive tape.

Another object of the present invention is to provide a structural adhesive tape and a preparation method thereof, and a method for preserving a vacancy of a tab on an electrode sheet, which can improve the utilization rate of the active material of the battery and avoid waste of the active material, and at the same time Improve battery energy density, fast-shooting performance and heat dissipation.

In order to achieve the above object, in one aspect of the invention, the present invention provides a structural adhesive tape comprising: an adhesive layer for attaching to an object to be pasted; and a substrate located at a distance from the structural adhesive tape Paste one side of the object. The adhesive layer includes a first adhesive, a first curing agent, a second adhesive, a second curing agent, and blowing agent particles distributed therein. The curing temperature of the first adhesive and the first curing agent is 20 ° C to 80 ° C; the curing temperature of the second adhesive and the second curing agent is greater than 80 ° C and less than or equal to 180 ° C.

In another aspect of the present invention, the present invention provides a method for preparing a structural adhesive tape for preparing the structural adhesive tape according to one aspect of the present invention, comprising the steps of: first adhesive, first curing agent, The second adhesive and the second curing agent are dissolved in the solvent, and after being uniformly stirred, the foaming agent particles are added to form a slurry; the slurry is coated on one surface of the substrate, and then dried in an oven. The solvent is removed; the structural adhesive tape is taken out from the oven and then matured to complete the preparation of the structural adhesive tape.

In still another aspect of the present invention, the present invention provides a method of preserving a tab vacancy in an electrode sheet, comprising the steps of: pasting a structure according to an aspect of the invention on a reserved area on a current collector of the electrode sheet Adhesive paper, the adhesive layer of the structural adhesive paper is pasted on the current collector, and the electrode slurry is coated on the surface of the structural adhesive paper substrate to obtain a wet film; the wet film is sent to the low temperature zone of the oven for baking. The structural adhesive paper still remains bonded to the current collector, wherein the baking temperature in the low temperature zone is less than the initial foaming temperature of the foaming agent particles; the wet film is continuously sent to the high temperature zone of the oven for baking, so that the structural adhesive tape is The foaming agent particles are foamed, the structural adhesive paper is curled, and the bonding force between the structural adhesive paper and the current collector is not more than 4 N/cm ² , wherein the baking temperature in the high temperature region is greater than or equal to the blowing agent particles. The initial foaming temperature; after the baking is finished, the structural adhesive tape is peeled off, and the tab hole is reserved in the electrode sheet.

Compared with the prior art, the beneficial effects of the present invention are:

The structural adhesive paper of the invention has extremely high viscosity consistency with the object to be pasted, and is easy to be mass-produced, and solves the problem that the viscosity of the foaming agent particles in the conventional adhesive paper is severe after foaming.

The structural adhesive tape of the invention can improve the utilization rate of the active material of the battery, avoid the waste of the active material, and at the same time improve the energy density, fast-release performance and heat dissipation performance of the battery.

DRAWINGS

1 is a perspective view of a current collector of a bonded object to which a structural adhesive tape according to the present invention is applied;

Figure 2 is a perspective view of a structural adhesive tape adhered to a current collector of a bonded object according to the present invention;

Figure 3 is a perspective view of a structural adhesive coated electrode slurry according to the present invention;

Figure 4 is a perspective view of the structural adhesive tape after peeling according to the present invention;

Figure 5 is a perspective view of a structural adhesive tape according to the present invention;

Figure 6 is a front view of Figure 5;

7A to 7B are respectively schematic views of an embodiment of a prior art adhesive tape, wherein FIG. 7A shows a schematic view of the foaming agent particles before foaming, and FIG. 7B shows a schematic view of the foaming agent particles after foaming;

8A to 8B are respectively schematic views of another embodiment of the prior art adhesive tape, wherein FIG. 8A shows a schematic view of the foaming agent particles before foaming, and FIG. 8B shows a schematic view of the foaming agent particles after foaming;

9A to 9B are respectively schematic views of still another embodiment of the prior art adhesive tape, wherein Fig. 9A shows a schematic view of the foaming agent particles before foaming, and Fig. 9B shows a schematic view of the foaming agent particles after foaming.

Among them, the reference numerals are as follows:

1 structural adhesive tape

11 adhesive layer

111 foaming agent particles

12 substrate

2 current collector

21 reserved area

3 electrode paste

W width direction

L length direction

T thickness direction

1' substrate

2' adhesive layer

21' foaming agent particles

detailed description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a structural adhesive tape according to the present invention and a method for preparing the same will be described in detail, and a method of vacating a tab in an electrode sheet will be described.

First, the structural adhesive tape according to the first aspect of the invention will be explained.

Referring to FIG. 3, FIG. 5 to FIG. 6, the structural adhesive tape 1 according to the first aspect of the present invention comprises: an adhesive layer 11 for sticking on an object to be pasted; and a substrate 12 which is located away from the structural adhesive tape 1. The side of the object being pasted. The adhesive layer 11 includes a first adhesive, a first curing agent, a second adhesive, a second curing agent, and blowing agent particles 111 distributed therein. The curing temperature of the first adhesive and the first curing agent is 20 ° C to 80 ° C; the curing temperature of the second adhesive and the second curing agent is greater than 80 ° C and less than or equal to 180 ° C.

In the structural adhesive sheet 1 according to the first aspect of the present invention, preferably, the first adhesive and the second curing agent do not Cross-linking curing occurs; the second adhesive does not crosslink and cure with the first curing agent.

In the structural adhesive sheet 1 according to the first aspect of the present invention, a curing accelerator may be further included in the adhesive layer 11, and the first adhesive is adjusted by adjusting the composition and the content ratio of the curing accelerator. The curing temperature of a curing agent and the curing temperature of the second adhesive and the second curing agent.

In the structural adhesive sheet 1 according to the first aspect of the invention, the first adhesive may be selected from a hydroxyl group-containing (meth) acrylate copolymer. Preferably, the hydroxyl group-containing (meth) acrylate copolymer may be selected from a solvent type hydroxy group-containing (meth) acrylate copolymer.

In the structural adhesive sheet 1 according to the first aspect of the invention, the monomer component of the hydroxyl group-containing (meth) acrylate copolymer may include a hydroxyl group-containing (meth) acrylate functional monomer. The hydroxyl group-containing (meth) acrylate functional monomer may be selected from one or more selected from the group consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

In the structural adhesive sheet 1 according to the first aspect of the invention, the monomer component of the hydroxyl group-containing (meth) acrylate copolymer may further include: a (meth)acrylic monomer. The (meth)acrylic monomer may be selected from the group consisting of acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and tert-butyl methacrylate. Ester, hexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, One or more of n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, ethyl 2-ethyl acrylate, 2-ethylhexyl acrylate.

In the structural adhesive sheet 1 according to the first aspect of the invention, the monomer component of the hydroxyl group-containing (meth) acrylate copolymer may further include a vinyl-based monomer. The vinylic monomer may be selected from vinyl acetate.

In the structural adhesive sheet 1 according to the first aspect of the invention, the first curing agent may be selected from one or more of a polythiol, a polyisocyanate. Wherein, the polythiol may be selected from one or more of n-dodecyl mercaptan, secondary dodecyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, thioglycolic acid. The polyisocyanate may be selected from the group consisting of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), benzene dimethylene diisocyanate ( XDI), one or more of methylcyclohexyl diisocyanate (HTDI), dicyclohexylmethane diisocyanate (HMDI), p-phenylene diisocyanate (PPDI), dimethylbiphenyl diisocyanate (TODI).

In the structural adhesive sheet 1 according to the first aspect of the invention, the second adhesive may be selected from an amine group-containing (meth) acrylate copolymer. Preferably, the amine group-containing (meth) acrylate copolymer may be selected from a solvent type amine group-containing (meth) acrylate copolymer.

In the structural adhesive sheet 1 according to the first aspect of the invention, the monomer component of the amine group-containing (meth) acrylate copolymer may include: an amine group-containing (meth) acrylate functional sheet body. The amine group-containing (meth) acrylate functional monomer may be selected from dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, and tert-butyl methacrylate. One or more of aminoethyl ethyl ester, diethylaminoethyl methacrylate, and N,N-diethylaminoethyl acrylate.

In the structural adhesive sheet 1 according to the first aspect of the invention, the monomer component of the amine group-containing (meth) acrylate copolymer may further include: a (meth)acrylic monomer. The (meth)acrylic monomer may be selected from the group consisting of acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and tert-butyl methacrylate. Ester, hexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, One or more of n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, ethyl 2-ethyl acrylate, 2-ethylhexyl acrylate.

In the structural adhesive sheet 1 according to the first aspect of the invention, the monomer component of the amine group-containing (meth) acrylate copolymer may further include a vinyl-based monomer. The vinylic monomer may be selected from vinyl acetate.

In the structural adhesive sheet 1 according to the first aspect of the invention, the second curing agent may be selected from epoxy resins. The specific kind of the epoxy resin is not limited. Preferably, the epoxy resin may be selected from one or more of E42, E44, E51, E54, Ex40, Ex48, F44, F48, F51, JF43, JF45.

In the structural adhesive tape 1 according to the first aspect of the present invention, when the curing temperature of the first adhesive and the first curing agent is less than 20 ° C, it is easy to cause curing at room temperature, resulting in an adhesive layer. The slurry gel of 11 can not be coated on the substrate 12, so that the structural adhesive paper 1 is scrapped; when the curing temperature of the first adhesive and the first curing agent is greater than 80 ° C, the curing temperature is lower than the structural adhesive. At the curing temperature of the paper 1, the adhesive layer 11 is incompletely cured during the curing process, and the residual glue appears on the current collector 2, and the residual glue cannot be peeled off, that is, the ear can not be reserved on the current collector 2. Vacancies for soldering the ears.

In the structural adhesive sheet 1 according to the first aspect of the invention, preferably, the curing temperature of the first adhesive and the first curing agent is from 40 ° C to 50 ° C.

In the structural adhesive tape 1 according to the first aspect of the present invention, when the curing temperature of the second adhesive and the second curing agent is less than 80 ° C, the structural adhesive paper 1 is liable to cause early loss of adhesion during use. Referring to Figures 3 and 4, the structural adhesive tape 1 is easily carried by the hot air, adhered to the wet film area (wet electrode paste 3), contaminating the finally formed film; when the second adhesive and the second curing agent are When the curing temperature is higher than 180 ° C, the surface adhesive sheet 3 is excessively dried during the use of the structural adhesive paper 1 , and a series of problems such as cracking of the film, streaking, and denaturation of the active material occur.

In the structural adhesive sheet 1 according to the first aspect of the invention, preferably, the curing temperature of the second adhesive and the second curing agent is from 105 ° C to 115 ° C.

In the structural adhesive sheet 1 according to the first aspect of the invention, the structural adhesive sheet 1 may have a total thickness of from 20 μm to 120 μm. Preferably, the structural adhesive paper 1 may have a total thickness of 40 μm to 70 μm. The total thickness of the structural adhesive tape 1 means the sum of the thickness of the substrate 12 and the thickness of the adhesive layer 11.

In the structural adhesive sheet 1 according to the first aspect of the invention, the area of the structural adhesive sheet 1 may be from 1 mm ² to 600 mm ² . Preferably, the area of the structural adhesive tape 1 may be from 80 mm ² to 480 mm ² .

In the structural adhesive sheet 1 according to the first aspect of the invention, the substrate 12 may be selected from polyethylene terephthalate.

In the structural adhesive sheet 1 according to the first aspect of the invention, the particle size of the blowing agent particles 111 may be from 5 μm to 30 μm.

In the structural adhesive sheet 1 according to the first aspect of the invention, the foaming agent particles 111 may have a foaming temperature of from 105 ° C to 150 ° C. Preferably, the foaming agent particles 111 may have a foaming temperature of from 110 ° C to 140 ° C. Further preferably, the foaming agent particles 111 may have a foaming temperature of from 120 ° C to 130 ° C.

In the structural adhesive sheet 1 according to the first aspect of the invention, the blowing agent particles 111 may be a physical foaming agent and/or a chemical foaming agent. Wherein, the physical foaming agent is an alkane long-chain series foaming agent. Preferably, the physical blowing agent may be selected from one or more of an isopentane blowing agent, an isobutane blowing agent, and a cyclopentane blowing agent. The chemical blowing agent may be selected from the group consisting of azodicarbonamide (AC), azobisisobutyronitrile (AIBN), N,N-dinitrosopentamethylenetetramine (DPT), 4,4' One or more of oxobisbenzenesulfonylhydrazide (OBSH) and p-toluenesulfonylhydrazide (TSH).

Next, a method for preparing the structural adhesive paper 1 according to the second aspect of the present invention for preparing the structural adhesive paper 1 according to the first aspect of the present invention includes the steps of: first adhesive, first curing agent, and The second adhesive and the second curing agent are dissolved in the solvent, and after being uniformly stirred, the foaming agent particles 111 are added to form a slurry; the slurry is coated on one surface of the substrate 12, and then dried in an oven. To remove the solvent; the structural adhesive paper 1 was taken out from the oven and then matured to complete the preparation of the structural adhesive paper 1.

In the method for preparing the structural adhesive paper 1 according to the second aspect of the present invention, a curing accelerator may be added during the preparation of the slurry, and the first adhesive is adjusted by adjusting the composition and the content ratio of the curing accelerator. The curing temperature of the adhesive and the first curing agent and the curing temperature of the second adhesive and the second curing agent.

In the method for preparing the structural adhesive sheet 1 according to the second aspect of the present invention, the oven temperature may be set to be not lower than the curing temperature of the first adhesive and the first curing agent, and lower than the second adhesive. The curing temperature with the second curing agent.

In the method of producing the structural adhesive sheet 1 according to the second aspect of the present invention, the oven temperature can be set to 70 ° C to 80 ° C.

In the method of producing the structural adhesive sheet 1 according to the second aspect of the present invention, the baking time may be from 1 min to 2 min.

In the method for producing the structural adhesive sheet 1 according to the second aspect of the present invention, the curing temperature is not excessively high, otherwise the outer wall of the blowing agent particles 111 is easily hardened, so that the foaming force is reduced. Specifically, the curing temperature may be from 20 ° C to 60 ° C. Preferably, the curing temperature may be from 40 ° C to 60 ° C. Further preferably, the aging temperature is from 40 ° C to 45 ° C.

In the method of producing the structural adhesive sheet 1 according to the second aspect of the present invention, the aging time may be 60 h or more.

A method of reserving the vacancies of the tabs on the electrode sheets according to the third aspect of the invention will be explained again.

Referring to FIGS. 1 through 6, a method of preserving a pole vacancy in an electrode sheet according to a third aspect of the present invention includes the steps of: pasting a reserved area 21 on a current collector 2 of an electrode sheet according to the first aspect of the present invention The adhesive tape 1 is adhered to the current collector 2 of the adhesive tape 1 of the structural adhesive paper 1, and the electrode paste 3 is coated on the surface of the substrate 12 of the structural adhesive paper 1 to obtain a wet film; After being sent to the low temperature zone of the oven for baking, the structural adhesive paper 1 remains bonded to the current collector 2, wherein the baking temperature in the low temperature zone is lower than the initial foaming temperature of the foaming agent particles 111; the wet film is continuously fed into the oven The high temperature zone is baked to foam the foaming agent particles 111 in the structural adhesive paper 1, the structural adhesive paper 1 is curled, and the bonding force between the structural adhesive paper 1 and the current collector 2 is not more than 4 N/cm ² Wherein, the baking temperature in the high temperature zone is greater than or equal to the initial foaming temperature of the foaming agent particles 111; after the baking is completed, the structural adhesive tape 1 is peeled off, and the tab space is reserved in the electrode sheet.

In the method for preserving the vacancies of the electrode pads according to the third aspect of the present invention, the oven temperature should be set to a low temperature zone and a high temperature zone, and the baking temperature of the low temperature zone is used for preheating drying of the electrode paste 3, The fluidity of the electrode paste 3 is reduced, and the baking temperature of the high temperature region is used to cure the second adhesive and the second curing agent, and to foam the blowing agent particles 111.

In the method for preserving the vacancy of the electrode tab in the electrode sheet according to the third aspect of the present invention, the baking temperature in the low temperature region is too low, which easily causes the electrode paste 3 to be effectively dried during the baking process, resulting in poor drying; The baking temperature in the low temperature zone is too high, and the foaming agent particles 111 are easily foamed in advance, and the structural adhesive tape 1 is prone to early premature sticking during use. Referring to FIG. 3 and FIG. 4, the structural adhesive tape 1 is easily taken up by the hot air. , adhered to the wet film area (wet electrode paste 3), contaminating the electrode film that is finally formed.

In the method of preserving the tab vacancies in the electrode sheet according to the third aspect of the present invention, specifically, the baking temperature in the low temperature region may be 40 ° C to 105 ° C. Preferably, the baking temperature in the low temperature zone may be from 80 ° C to 100 ° C.

In the method of preserving the vacancies in the electrode sheets according to the third aspect of the present invention, the baking temperature in the high temperature region is too low, and the foaming agent particles 111 cannot be effectively foamed, resulting in poor foaming of the structural adhesive paper 1. After the current collector 2 is removed from the oven, the structural adhesive paper 1 cannot be peeled off from the current collector 2, and thus the pole vacancies cannot be reserved on the current collector 2; the baking temperature in the high temperature region is too high, which easily leads to structural adhesive The electrode paste 3 on the surface of the paper 1 is excessively dried, and a series of problems such as cracking of the film, streaking, and denaturation of the active material occur.

In the method of preserving the tab vacancies in the electrode sheet according to the third aspect of the present invention, specifically, the baking temperature in the high temperature region may be from 105 ° C to 180 ° C. Preferably, the baking temperature in the high temperature zone may be from 125 ° C to 145 ° C. Further preferably, the baking temperature in the high temperature region may be from 130 ° C to 135 ° C.

In the method of preserving the tab vacancies in the electrode sheet according to the third aspect of the present invention, the baking time in the low temperature region may be 30 s to 300 s. Preferably, the baking time in the low temperature zone may be 30 s to 60 s.

In the method of preserving the tab vacancies in the electrode sheet according to the third aspect of the present invention, the baking time in the high temperature region may be 30 s to 300 s. Preferably, the baking time in the high temperature zone may be from 30 s to 120 s.

In the method for preserving the vacancies of the electrode tab according to the third aspect of the present invention, the adhesion between the structural adhesive tape 1 and the current collector 2 after the end of the low temperature region is not more than 50 N/cm ² , After the end of the baking in the low temperature zone, the structural adhesive paper 1 remains bonded to the current collector 2.

In the method of preserving the tab vacancies in the electrode sheet according to the third aspect of the present invention, preferably, the bonding force between the structural adhesive tape 1 and the current collector 2 after the end of the low temperature region baking may be 1 N/ Cm ² to 23 N/cm ² .

In the method of preserving the tab vacancies in the electrode sheet according to the third aspect of the present invention, the coating thickness of the electrode paste 3 is thick. The degree may be from 40 μm to 300 μm. Preferably, the electrode paste 3 may have a coating thickness of 60 μm to 180 μm.

The present application is further illustrated below in conjunction with the embodiments. It is to be understood that the examples are not intended to limit the scope of the application.

The structural adhesive sheets of Examples 1-5 and Comparative Examples 1-20 were prepared as follows:

At room temperature, the first adhesive (2-ethylhexyl acrylate + vinyl acetate + hydroxyethyl acrylate copolymer), the first curing agent (toluene diisocyanate, TDI), the second adhesive (acrylic acid - 2-ethylhexyl ester + vinyl acetate + dimethylaminoethyl methacrylate copolymer), second curing agent (epoxy resin E51) and curing accelerator dissolved in solvent toluene and ethyl acetate 1:1 (V / The mixture of V) was stirred at a number of revolutions of 40 rpm to 60 rpm for 30 minutes; then, foaming agent particles AC (foaming temperature of 115 ° C to 125 ° C) were added, and stirring was continued for 30 minutes at a number of revolutions of 40 rpm to 60 rpm to obtain a slurry.

The slurry was coated on a substrate PET (thickness: 15 μm) using a conventional doctor blade to form a roll I (total thickness of 60 μm), and then the solvent was removed by baking in an oven, and the running speed of the roll I was 15 m/min.

The structural adhesive tape is matured and cut and shipped.

The curing temperature of the first adhesive and the first curing agent, the curing temperature of the second adhesive and the second curing agent, the baking process parameters, and the curing process parameters are shown in Table 1.

Table 1 Preparation parameters of structural adhesive sheets of Examples 1-5 and Comparative Examples 1-20

Next, the structural adhesive sheets of Examples 1-5 and Comparative Examples 1-20 were pasted on a reserved area on the current collector aluminum foil, and the adhesive layer of the structural adhesive paper was stuck on the current collector, and a pressure of 2 kg was used. The roller was rolled back and forth 6 times, and then the structural adhesive tape was peeled off to observe whether or not residual glue appeared on the surface of the current collector. If no residual glue appears, re-take a piece of structural adhesive paper and paste it on the reserved area on the current collector aluminum foil, and apply the positive electrode slurry on the surface of the substrate PET of the structural adhesive paper to obtain a wet film; The film is sent to the low temperature zone of the oven for baking; then the wet film is sent to the high temperature zone of the oven for baking, so that the structural adhesive tape is foamed and curled; after the baking is finished, the structural adhesive tape is peeled off, and the film can be reserved in the positive electrode sheet. The ear is empty. Among them, the low temperature zone baking temperature and time, the high temperature zone baking temperature and time are shown in Table 2.

Table 2 Baking parameters and test results of structural adhesive sheets of Examples 1-5 and Comparative Examples 1-20

As can be seen from Table 2, in the examples 1-5, when the structural adhesive paper is baked in a low temperature zone, the structural adhesive paper remains bonded to the current collector, and at this time, the foaming agent particles have not been foamed; When the structural adhesive paper is baked in the high temperature zone, the foaming agent particles foam to make the structural adhesive paper curl, and the second adhesive and the epoxy resin E51 are quickly cross-linked and solidified, and the cohesive force inside the adhesive layer rises rapidly, and the adhesive The viscosity of the adhesive layer drops rapidly, and the structural adhesive tape is easily peeled off from the current collector (for example, by a mechanical brush) without causing residual glue.

In Comparative Examples 1-5, the curing temperature of the first adhesive and the first curing agent is too low, resulting in opening at room temperature. The curing begins, causing the slurry gel of the adhesive layer to be coated on the substrate, and the structural adhesive paper is scrapped.

In Comparative Examples 6-7, the curing temperature of the second adhesive and the second curing agent was 70 ° C, and the curing temperature was low. When baking in the high temperature region, the second adhesive was cured by crosslinking with the epoxy resin E51. Too fast, the cohesive force inside the adhesive layer rises rapidly, so that the adhesiveness of the adhesive layer of the structural adhesive paper drops too fast, resulting in early loss of adhesion of the structural adhesive tape and contamination of the film.

In the comparative examples 9-12, 19, the curing temperature of the first adhesive and the first curing agent is 80 ° C, which is greater than the curing temperature of the structural adhesive paper, resulting in incomplete curing of the first adhesive and the first curing agent. When the surface of the current collector is pasted, residual glue appears, which causes the structural adhesive paper to be scrapped.

In Comparative Examples 13-15, the baking temperature in the high temperature region is lower than the curing temperature of the second adhesive and the epoxy resin E51, and the second adhesive and the epoxy resin E51 cannot be cured in the high temperature region. The structural adhesive tape and the current collector still maintain a strong bond, which causes the structural adhesive tape to be peeled off, and thus the pole vacancies cannot be reserved on the current collector. In addition, the baking temperature in the high temperature zone is lower than the initial foaming temperature of the foaming agent particles, and the foaming agent particles cannot be effectively foamed, resulting in poor foaming of the structural adhesive paper, so that after the current collector is removed from the oven, the structure The adhesive tape cannot be peeled off from the current collector, and it is impossible to reserve a tab space on the current collector.

Similarly, in Comparative Examples 8, 16-17, although the baking temperature in the high temperature region is higher than the curing temperature of the second adhesive and the epoxy resin E51, the second adhesive and the epoxy resin E51 can be normally cured, but Since the baking temperature in the high temperature zone is still lower than the initial foaming temperature of the foaming agent particles, the foaming agent particles cannot be effectively foamed, resulting in poor foaming of the structural adhesive paper, so that the structural adhesive is removed after the current collector is removed from the oven. The paper cannot be peeled off from the current collector, and it is impossible to reserve a tab space on the current collector.

In Comparative Examples 14, 18, and 20, since the baking temperature in the low temperature region was too low, the positive electrode slurry could not be effectively dried during the baking process, and poor drying occurred.

Claims

A structural adhesive tape (1) comprising:

An adhesive layer (11) for adhering to the object to be pasted;

a substrate (12) located on a side of the structural adhesive tape (1) away from the object to be pasted;

It is characterized in that

The adhesive layer (11) includes a first adhesive, a first curing agent, a second adhesive, a second curing agent, and a blowing agent particle (111) distributed therein;

The curing temperature of the first adhesive and the first curing agent is 20 ° C ~ 80 ° C;

The curing temperature of the second adhesive and the second curing agent is greater than 80 ° C and less than or equal to 180 ° C.
The structural adhesive paper (1) according to claim 1, wherein the first adhesive is selected from a hydroxyl group-containing (meth) acrylate copolymer, and the hydroxy group-containing (meth) acrylate copolymer The monomer component includes: a hydroxyl group-containing (meth) acrylate functional monomer.
The structural adhesive paper (1) according to claim 2, wherein the hydroxyl group-containing (meth) acrylate copolymer is selected from a solvent type hydroxy group-containing (meth) acrylate copolymer.
The structural adhesive paper (1) according to claim 2, wherein the hydroxyl group-containing (meth) acrylate functional monomer is selected from the group consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxyethyl methacrylate. One or more of hydroxypropyl methacrylate.
The structural adhesive sheet (1) according to claim 2, wherein the monomer component of the hydroxyl group-containing (meth) acrylate copolymer further comprises: a (meth)acrylic monomer.
The structural adhesive paper (1) according to claim 5, wherein the (meth)acrylic monomer is selected from the group consisting of acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, and methyl group. N-butyl acrylate, isobutyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, acrylic acid Methyl ester, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, ethyl 2-ethyl acrylate, One or more of 2-ethylhexyl acrylate.
The structural adhesive paper (1) according to claim 5, wherein the hydroxyl group-containing (meth) propyl group The monomer component of the enoate copolymer further includes a vinyl monomer.
The structural adhesive paper (1) according to claim 7, wherein the vinyl monomer is selected from the group consisting of vinyl acetate.
The structural adhesive sheet (1) according to claim 1, wherein the first curing agent is one or more selected from the group consisting of polythiols and polyisocyanates.
The structural adhesive tape (1) according to claim 9, wherein

The polythiol is selected from one or more of n-dodecyl mercaptan, secondary dodecyl mercaptan, tert-dodecyl mercaptan, mercaptoethanol, thioglycolic acid;

The polyisocyanate is selected from the group consisting of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, benzene dimethylene diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate One or more of p-phenylene diisocyanate and dimethylbiphenyl diisocyanate.
The structural adhesive paper (1) according to claim 1, wherein the second adhesive is selected from the group consisting of an amine group-containing (meth) acrylate copolymer, and the amine group-containing (meth) acrylate The monomer component of the copolymer includes: an amine group-containing (meth) acrylate functional monomer.
The structural adhesive paper (1) according to claim 11, wherein the amine group-containing (meth) acrylate copolymer is selected from the group consisting of solvent-based amine group-containing (meth) acrylate copolymers.
The structural adhesive paper (1) according to claim 11, wherein the amine group-containing (meth) acrylate functional monomer is selected from the group consisting of dimethylaminoethyl acrylate and dimethylamine methacrylate One or more of an ester, t-butylaminoethyl methacrylate, diethylaminoethyl methacrylate, and N,N-diethylaminoethyl acrylate.
The structural adhesive sheet (1) according to claim 11, wherein the monomer component of the amine group-containing (meth) acrylate copolymer further comprises: a (meth)acrylic monomer.
The structural adhesive paper (1) according to claim 14, wherein the (meth)acrylic monomer is selected from the group consisting of acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, and methyl group. N-butyl acrylate, isobutyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, acrylic acid Methyl ester, ethyl acrylate, n-propyl acrylate, acrylic acid One of isopropyl ester, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, ethyl 2-ethyl acrylate, 2-ethylhexyl acrylate or Several.
The structural adhesive sheet (1) according to claim 14, wherein the monomer component of the amine group-containing (meth) acrylate copolymer further comprises a vinyl monomer.
A structural adhesive tape (1) according to claim 16, wherein the vinylic monomer is selected from the group consisting of vinyl acetate.
The structural adhesive tape (1) according to claim 1, wherein the second curing agent is selected from the group consisting of epoxy resins.
The structural adhesive tape (1) according to claim 1, wherein

The curing temperature of the first adhesive and the first curing agent is 40 ° C ~ 50 ° C;

The curing temperature of the second adhesive and the second curing agent is from 105 ° C to 115 ° C.
The structural adhesive paper (1) according to claim 1, characterized in that the total thickness of the structural adhesive paper (1) is from 20 μm to 120 μm, preferably, the total thickness of the structural adhesive paper (1) is from 40 μm to 70 μm.
The structural adhesive paper (1) according to claim 1, wherein the structural adhesive paper (1) has an area of from 1 mm 2 to 600 mm 2 , preferably, the structural adhesive paper (1) has an area of from 80 mm 2 to 480 mm 2 . .
A structural adhesive tape (1) according to claim 1, characterized in that the substrate (12) is selected from the group consisting of polyethylene terephthalate.
The structural adhesive paper (1) according to claim 1, wherein the foaming agent particles (111) have a particle diameter of from 5 μm to 30 μm.
The structural adhesive paper (1) according to claim 1, wherein the foaming agent particles (111) have a foaming temperature of from 105 ° C to 150 ° C, preferably a foaming temperature of the blowing agent particles (111) It is more preferably from 110 ° C to 140 ° C, and further preferably, the foaming agent particles (111) have a foaming temperature of from 120 ° C to 130 ° C.
A structural adhesive paper (1) according to claim 24, characterized in that the blowing agent particles (111) are physical A blowing agent and/or a chemical blowing agent.
A structural adhesive tape (1) according to claim 25, wherein

The physical blowing agent is selected from one or more of an isopentane blowing agent, an isobutane blowing agent, and a cyclopentane blowing agent;

The chemical blowing agent is selected from the group consisting of azodicarbonamide, azobisisobutyronitrile, N,N-dinitrosopentamethylenetetramine, 4,4'-oxobisbenzenesulfonyl hydrazide, One or more of tosylhydrazide.
A method for preparing a structural adhesive paper (1) for preparing the structural adhesive paper (1) according to any one of claims 1 to 26, comprising the steps of:

Dissolving the first adhesive, the first curing agent, the second adhesive, and the second curing agent in a solvent, stirring uniformly, and adding the blowing agent particles (111) to form a slurry;

Coating the slurry on one of the surfaces of the substrate (12), followed by drying in an oven to remove the solvent;

The structural adhesive paper (1) is taken out from the oven and then matured to complete the preparation of the structural adhesive paper (1).
The method for preparing a structural adhesive tape (1) according to claim 27, wherein the oven temperature is not lower than a curing temperature of the first adhesive and the first curing agent, and lower than the second adhesive and the second adhesive The curing temperature of the second curing agent.
The method of producing a structural adhesive sheet (1) according to claim 27, wherein the oven temperature is set to 70 ° C to 80 ° C.
The method for preparing a structural adhesive sheet (1) according to claim 27, wherein the baking time is from 1 min to 2 min.
The method for producing a structural adhesive sheet (1) according to claim 27, wherein the curing temperature is from 20 ° C to 60 ° C, preferably, the curing temperature is from 40 ° C to 60 ° C, and more preferably, the curing temperature is 40 °C ~ 45 °C.
The method for producing a structural adhesive sheet (1) according to claim 27, wherein the ripening time is 60 h or more.
A method for preserving a pole vacancy in an electrode sheet, comprising the steps of:

Adhesive layer (1) according to any one of claims 1-26 is adhered to a reserved area (21) on the current collector (2) of the electrode sheet to make the adhesive layer of the structural adhesive paper (1) (11) pasting on the current collector (2), coating the electrode slurry (3) on the surface of the substrate (12) of the structural adhesive paper (1) to obtain a wet film;

The wet film is sent to the low temperature zone of the oven for baking, and the structural adhesive paper (1) remains bonded to the current collector (2), wherein the baking temperature in the low temperature zone is lower than the initial foaming of the foaming agent particles (111). temperature;

The wet film is continuously sent to the high temperature zone of the oven for baking, the foaming agent particles (111) in the structural adhesive paper (1) are foamed, the structural adhesive paper (1) is curled, and the structural adhesive paper (1) is The binding force between the current collectors (2) is not more than 4 N/cm 2 , wherein the baking temperature in the high temperature region is greater than or equal to the initial foaming temperature of the blowing agent particles (111);

After the baking is finished, the structural adhesive tape (1) is peeled off, and the tabs are reserved in the electrode sheets.
The method for preserving a tab space in an electrode sheet according to claim 33, wherein the baking temperature in the low temperature region is 40 ° C to 105 ° C, preferably, the baking temperature in the low temperature region is 80 ° C to 100 ° C .
The method for preserving a tab space in an electrode sheet according to claim 33, wherein the baking temperature in the high temperature region is 105 ° C to 180 ° C, preferably, the baking temperature in the high temperature region is 125 ° C to 145 ° C Further preferably, the baking temperature in the high temperature region is from 130 ° C to 135 ° C.
The method for preserving the vacancies in the electrode sheets according to claim 33, wherein the baking time in the low temperature region is 30 s to 300 s, and preferably, the baking time in the low temperature region is 30 s to 60 s.
The method for preserving the vacancies in the electrode sheets according to claim 33, wherein the baking time in the high temperature region is 30 s to 300 s, and preferably, the baking time in the high temperature region is 30 s to 120 s.
The method for preserving a pole vacancy in an electrode sheet according to claim 33, wherein the bonding force between the structural adhesive tape (1) and the current collector (2) after the baking in the low temperature region is not more than 50N /cm 2 , preferably, the adhesion between the structural adhesive tape (1) and the current collector (2) after the end of baking in the low temperature zone is from 1 N/cm 2 to 23 N/cm 2 .
A method of preserving a vacancy of a tab on an electrode sheet according to claim 33, wherein the coating thickness of the electrode paste (3) is from 40 μm to 300 μm, preferably, the coating thickness of the electrode paste (3) It is 60 μm to 180 μm.