CN106811143B - Structural adhesive paper - Google Patents

Abstract

The invention provides a structural adhesive paper, which is used for sticking on the object to be bonded. The dyne value of the outer surface of the structural adhesive tape opposite to the object to be bonded is 20 dyn/cm to 28 dyn/cm. The structural adhesive tape includes: an adhesive layer for sticking on the object to be bonded; and a substrate, one surface of the substrate is pasted on the adhesive layer, and the other surface of the substrate itself serves as the structure The outer surface of the adhesive paper opposite to the object to be bonded, or the other surface of the substrate is surface-treated and the surface-treated surface is used as the outer surface of the structural adhesive paper opposite to the object to be bonded. The structural adhesive paper of the present invention can eliminate the bulge of the active material layer at the edge of the structural adhesive paper. The structural adhesive paper of the invention can improve the utilization rate of the active material, avoid the waste of the active material, and at the same time improve the energy density, fast charging and fast discharging and heat dissipation performance of the battery.

Description

Structural tape

technical field

The invention relates to the field of adhesive paper, in particular to a structural adhesive paper.

Background technique

Currently, before the pole pieces of the lithium ion battery are coated, it is necessary to reserve the position of the tab on the current collector to ensure that the welding position of the tab is the empty foil area of the current collector that is not coated with the active material layer. In the prior art, conventional structural adhesive tape is added at the position of the tab before coating, and the adhesive surface corresponds to the empty foil area. After the coating operation is completed, the adhesive tape is removed to reserve a position for the tab. In the coating process, the active material layer covers the empty foil area and the tape, and then two temperature areas are set in the drying tunnel in the drying process, wherein the former temperature area is the drying temperature area of the active material layer, and the latter The warm area is the thermal peeling temperature area of the adhesive paper. The purpose of reserving an empty foil area in the active material layer is achieved by drying the active material layer and curling and peeling the adhesive paper when heated.

However, the use of conventional structural adhesive paper has the following problems: Referring to FIG. 13 , since the coating of the active material layer 3 ′ belongs to quantitative coating, the structural adhesive paper 1 will occupy part of the space of the active material layer 3 , resulting in 'The active material layer 3' at the edge forms a protrusion with a certain height difference. When the structural adhesive tape 1 is heated, curled and peeled off, the bulge at the peeling edge cannot be eliminated. In the subsequent rolling process, the current collector 2' at the bulge will be subjected to excessive shearing force, which will cause the foil to become brittle and even become brittle. Fractures occurred, resulting in the inability of the process to proceed normally. In addition, the thickness of the active material layer 3' at the peeled edge of the conventional structural adhesive tape 1' is larger than that of the active material layer 3' in the normal area, which leads to more prone to breakage in the subsequent rolling process.

SUMMARY OF THE INVENTION

In view of the problems existing in the background art, the purpose of the present invention is to provide a structural adhesive paper, which can eliminate the bulge of the active material layer at the edge of the structural adhesive paper.

Another object of the present invention is to provide a structural adhesive tape, which can improve the utilization rate of active materials, avoid waste of active materials, and at the same time improve the energy density, fast charging and fast discharging and heat dissipation performance of batteries.

In order to achieve the above object, in one aspect of the present invention, the present invention provides a structural adhesive tape, which is used for sticking on an object to be bonded. The dyne value of the outer surface of the structural adhesive tape opposite to the object to be bonded is 20 dyn/cm to 28 dyn/cm. The structural adhesive tape includes: an adhesive layer for sticking on the object to be bonded; and a substrate, one surface of the substrate is pasted on the adhesive layer, and the other surface of the substrate itself serves as the structure The outer surface of the adhesive paper opposite to the object to be bonded, or the other surface of the substrate is surface-treated and the surface-treated surface is used as the outer surface of the structural adhesive paper opposite to the object to be bonded.

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

The dyne value of the outer surface opposite to the object to be bonded of the structural adhesive tape of the present invention is low, so the surface energy is low, the bulge of the active material layer at the edge of the structural adhesive tape can be eliminated, and the extreme problem of the active material layer is solved. Edge bulge problem at ear position.

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

The structural adhesive paper of the present invention can meet the demand for mass production of batteries, and improve the productivity and high-quality rate of batteries.

Description of drawings

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

2 is a perspective view of the structure adhesive tape according to the present invention pasted on the current collector of the object to be bonded;

Fig. 3 is the perspective view of coating active material layer of structural adhesive tape according to the present invention;

Fig. 4 is the perspective view after peeling off the structural adhesive tape according to the present invention;

5 is a perspective view of another embodiment of the structure adhesive tape according to the present invention pasted on the current collector of the object to be bonded;

6 is a perspective view of yet another embodiment of the structural adhesive tape according to the present invention being attached to the current collector of the object to be bonded;

7 is a perspective view of an embodiment of the substrate of the structural adhesive tape according to the present invention;

8 is a perspective view of another embodiment of the base material of the structural adhesive tape according to the present invention;

9 is a perspective view of yet another embodiment of the base material of the structural adhesive tape according to the present invention;

10 is a perspective view of yet another embodiment of the base material of the structural tape according to the present invention;

11 is a cross-sectional view taken along line A-A of the structural adhesive tape of FIG. 3;

Figure 12 is an enlarged view of the circled portion of Figure 11;

13 is a cross-sectional view of the prior art structural adhesive tape coated with an active material layer applied to a current collector.

Among them, the reference numerals are described as follows:

1, 1' Structural Tape

11 Adhesive layer

12 Substrates

121 Sublayer

122 Sublayers

2, 2' glued object

21 Reserved area

3,3' active material layer

S, S _i , S _t , S _i1 , S _i2 , S _t1 , S _t2 surfaces

W width direction

L length direction

T thickness direction

Detailed ways

The structural tape according to the present invention will be described in detail below.

Referring to FIG. 1 to FIG. 4 , the structural adhesive tape 1 of the present invention is used for sticking on the object 2 to be bonded. The dyne value of the outer surface S of the structural tape 1 opposite to the object to be bonded 2 is 20 dyn/cm to 28 dyn/cm. Referring to FIGS. 5 to 6 , the structural adhesive tape 1 includes: an adhesive layer 11 for sticking on the object to be bonded 2 ; and a base material 12 . One surface of the substrate 12 is attached to the adhesive layer 11, and the other surface of the substrate 12 itself _Si (ie, the surface of the substrate 12 opposite to the one surface attached to the adhesive layer 11) serves as a structure The outer surface S of the adhesive tape 1 opposite to the object to be bonded 2, or the other surface of the substrate 12 (that is, the surface of the substrate 12 opposite to the one surface pasted on the adhesive layer 11) is subjected to surface treatment And the surface S _t after the surface treatment is used as the outer surface S of the structural adhesive tape 1 opposite to the object to be bonded 2 . 5 shows the other surface Si of the base material 12 itself, and FIG. 6 shows the surface S _t of the base material 12 after the surface treatment _. Both the surface S _i and the surface S _t can be used as the outer surface S of the structural adhesive tape 1 opposite to the object to be bonded 2 . The dyne value of the outer surface S of the structural adhesive tape 1 opposite to the object to be bonded 2 can be obtained by the dyne pen test.

In the structural adhesive tape 1 of the present invention, referring to FIGS. 1 to 4 , the object to be bonded 2 may be a current collector. Before coating the slurry of the active material layer 3 on the current collector, stick the structural tape 1 on the reserved area 21 of the current collector for forming the tabs, and bake the slurry after coating the slurry on the current collector Dry. After the drying is completed, the structural adhesive paper 1 is peeled off to form a reserved area 21 for the tabs.

In the structural adhesive tape 1 of the present invention, referring to FIGS. 11 to 12 , when the slurry of the active material layer 3 is coated on the outer surfaces of the object to be bonded 2 and the structural adhesive tape 1 , due to the The dyne value of the opposite outer surface S of the object to be bonded 2 is low, and the pulp located at the edge of the structural adhesive paper 1 is less bound by the structural adhesive paper 1. Therefore, under the action of the surface tension of the pulp, the pulp on the structural adhesive paper 1 The slurry at the edge slowly shrinks toward the nearby bonded object 2 (in Figure 7, it shrinks toward the bonded object 2 along the width direction W), and at the same time, the drying process of the slurry is also carried out simultaneously. When the residual amount of solvent in the material reaches a certain value, the slurry no longer migrates. At this time, the bulge at the edge of the structural tape 1 has been eliminated through the migration of the slurry, and the slurry forms an active material layer 3 after drying, and the active material layer 3 is formed. Substance layer 3 does not appear bulging. When the structural adhesive tape 1 is heated, curled and peeled off, there will be no bulge at the peeling edge, which solves the problem of the edge bulge at the position of the active material layer 3 tabs, and avoids tape breakage in the subsequent rolling process; at the same time, the active material is improved. It can improve the utilization rate of the battery and avoid the waste of active materials, thereby improving the energy density, fast charging and fast discharging, and heat dissipation performance of the battery.

When the active material slurry is used for a lithium ion battery, generally, the viscosity of the active material slurry of the lithium ion battery is 1000 mpa.s to 30000 mpa.s. For high-viscosity active material slurry (such as 30000mpa.s>viscosity>8000mpa.s), when the dyne value of the outer surface S of the structural tape 1 exceeds the upper limit, due to the poor fluidity of the high-viscosity active material slurry, certain conditions Lower (time control) cannot completely eliminate the edge protrusion of the structural adhesive paper 1; when the dyne value of the outer surface S of the structural adhesive paper 1 is lower than the lower limit, the interaction force between the pulp and the outer surface S of the structural adhesive paper 1 If it is too low, it is easy to cause all the slurry on the outer surface S of the structural adhesive tape 1 to migrate, and instead lead to aggravated edge protrusion. Preferably, the dyne value range of the outer surface S of the structural adhesive paper 1 satisfies 20 dyn/cm to 24 dyn/cm. For low-viscosity active material slurry (such as 8000mpa.s>viscosity>1000mpa.s), when the dyne value is lower than the lower limit, due to the good fluidity of the low-viscosity active material slurry, under certain conditions, it is easy to cause slurry Excessive migration results in increased edge bulge, and even when the dyne value exceeds the upper limit, edge bulge cannot be completely eliminated. Preferably, the dyne value range of the outer surface S of the structural adhesive paper 1 satisfies 24 dyn/cm to 28 dyn/cm.

The first type of structural tape 1 according to the present invention will be described below. Referring to FIG. 5 , the structural adhesive paper 1 may include an adhesive layer 11 and a base material 12 . The adhesive layer 11 is used to stick to the object to be bonded 2 . One surface of the base material 12 is pasted on the adhesive layer 11, the other surface Si of the base material 12 itself _serves as the outer surface S of the structural adhesive tape 1 opposite to the object to be bonded 2, and the other surface of the base material 12 is The _dyn value of Si on the surface itself is 20 dyn/cm to 28 dyn/cm. In the first type of structural adhesive paper, the substrate 12 with low surface energy is directly used to control the dyne value of the outer surface S of the structural adhesive paper 1 (ie the other surface of the substrate 12 itself Si) to 20 _dyn /cm～28dyn/cm, so as to achieve the purpose of eliminating edge bulge. In an embodiment of the first type of structural tape, referring to FIG. 7 , the substrate 12 may have a single-layer structure, and the surface S _i1 of the substrate 12 of the single-layer structure serves as the other surface S of the substrate 12 . _i , the substrate 12 may be polyfluoroolefin at this time.

In another embodiment of the first type of structural tape, referring to FIG. 8 , the substrate 12 may have N sub-layers, where N is greater than or equal to two. One surface of the sub-layer 121 of the substrate 12 close to the adhesive layer 11 (not shown) is pasted on the adhesive layer 11 , and the substrate 12 is far from the adhesive layer 11 and is at the outermost side of the substrate 12 . The outer surface S _i2 of the sub-layer 122 serves as the other surface S _i of the substrate 12 , and the material of the sub-layer 122 of the substrate 12 which is far from the adhesive layer 11 and at the outermost side of the substrate 12 can be polyfluoroolefin. The substrate 12 may have a multi-layer structure, as long as the material of the sub-layer 122 of the substrate 12 that is far from the adhesive layer 11 and is at the outermost side of the substrate 12 is polyfluoroolefin, and the materials of the remaining sub-layers are not affected. limit. Referring to FIG. 8 , the substrate 12 has a two-layer structure, as long as the material of the sub-layer 122 is polyfluoroolefin, and the material of the sub-layer 121 is not limited. Preferably, the material of the sub-layer 121 may be polyethylene terephthalate (PET), polyimide (PI) or polyamideimide (PAI).

The dyne value of the polyfluoroolefin surface can be 20 dyn/cm to 28 dyn/cm. Preferably, the polyfluoroolefin has a symmetrical structure. The polyfluoroolefin may be polytetrafluoroethylene or polyvinylidene fluoride. The carbon-fluorine bonds in polytetrafluoroethylene or polyvinylidene fluoride are symmetrical, so the polar bonds can cancel each other out. At the same time, due to the strong electronegativity of the fluorine atom and the strong ability to capture electrons, the non-overlapping of the positive center and the negative center caused by the instantaneous movement of electrons results in a small dispersion force, resulting in small surface tension and low surface energy. When the outer surface of the substrate 12 using polyfluoroolefin is in contact with the active material slurry, the force between the outer surface of the substrate 12 and the atoms or molecules of the active material slurry is small, the friction coefficient is low, and it is easy to achieve elimination. The purpose of the raised edge.

In the first type of structural tape, the material of the adhesive layer 11 may be acrylic resin or polyurethane.

In the first type of structural tape, the adhesive layer 11 may contain a foaming agent. When the structural adhesive tape 1 is heated, the foaming agent foams so that the structural adhesive tape 1 is curled from the opposite side edges of the width direction W to the middle part, effectively controlling the curling direction of the structural adhesive tape 1; The middle part of the adhesive tape is kept bonded to the bonded object 2 without peeling off, which can ensure an effective bonding area and prevent the structural adhesive tape 1 from falling off the bonded object 2 during the heating process. The blowing agent may be azodicarbonamide (AC) blowing agent or 4,4-oxobisbenzyl hydrazide (OBSH) blowing agent. The particle diameter of the blowing agent may be less than 30 μm. When the adhesive layer 11 contains a foaming agent, it is required that the thickness of the adhesive layer 11 may be larger than the particle diameter of the foaming agent and less than 70 μm. The thickness of the substrate 12 is not limited, and preferably may be less than 30 μm.

In the first type of structural adhesive tape, the base material 12 may be rectangular, which facilitates subsequent welding of the tabs.

Next, a second type of structural tape 1 according to the present invention will be explained. Referring to FIG. 6 , the structural adhesive paper 1 may include an adhesive layer 11 and a base material 12 . The adhesive layer 11 is used to stick to the object to be bonded 2 . One surface of the substrate 12 is pasted on the adhesive layer 11, the other surface of the substrate 12 is surface-treated, and the surface S _t after the surface treatment is used as the outer surface of the structural adhesive tape 1 opposite to the bonded object 2. For the surface S, the dyne value of the surface S _t of the substrate 12 after the surface treatment is 20 dyn/cm to 28 dyn/cm.

In the second type of structural adhesive tape, the surface treatment area on the other surface of the substrate 12 is at least the entire peripheral portion of the other surface of the substrate 12, so as to reduce the surface energy of the peripheral portion of the substrate 12, To achieve the purpose of subsequent elimination of edge bulges. Preferably, the surface treatment area of the other surface of the substrate 12 is the entire area of the other surface of the substrate 12 .

In the second type of structural adhesive paper, the surface-treated surface S _t of the substrate 12 can be obtained by coating the other surface of the substrate 12 with silicone oil. Because the molecular segments of the silicone oil are soft and the intermolecular force is small, the silicon-oxygen bond is easy to rotate. The oxygen atoms on the skeleton of the molecular segment are combined with the outer surface of the structural adhesive tape through intermolecular forces, so that the methyl groups in the silicone oil with low surface energy are aligned regularly on the outer surface of the structural adhesive tape. Groups such as methyl groups in this silicone oil have low electron attraction, form a low surface energy interface, and can keep their orientation stable in the temperature range of -40°C to 250°C, thereby achieving a stable isolation effect.

In the second type of structural adhesive paper, the silicone oil can be selected from one or more of polydimethylsiloxane, cyclomethicone, aminosiloxane, and polymethylphenylsiloxane. kind. The coating thickness of the silicone oil may be 0.2 μm to 1 μm. The silicone oil is coated at least on the entire peripheral portion of the other surface of the substrate 12 to reduce the surface energy of the substrate 12 and achieve the purpose of subsequently eliminating edge protrusions.

In the second type of structural adhesive paper, the surface-treated surface S _t of the substrate 12 can also be obtained by fluorinating the other surface of the substrate 12 . The surface after fluorination treatment can be grafted with fluorine group or fluorocarbon group of non-polar functional group to achieve the purpose of reducing the surface energy. The fluorinated area is at least the entire peripheral portion of the other surface of the substrate 12, so as to reduce the surface energy of the substrate 12 and achieve the purpose of subsequently eliminating edge protrusions. Specifically, the surface-treated surface can be obtained by performing fluorination treatment on the other surface of the substrate with a fluorine-containing plasma gas. The fluorine-containing plasma gas may be a plasma gas of CF ₄ or a mixed plasma gas of CF ₄ and CH ₄ .

In an embodiment of the second type of structural adhesive paper, referring to FIG. 9 , the substrate 12 may have a single-layer structure, and the other surface S _t1 of the substrate 12 of the single-layer structure is subjected to surface treatment to obtain the above-mentioned substrate 12 . Surface S _t after surface treatment. Since the surface-treated surface S _t of the substrate 12 is obtained by coating the other surface S _t1 of the substrate 12 with a single-layer structure with silicone oil or performing fluorination treatment, the material of the substrate 12 itself is not limited. Preferably, the substrate 12 may be polyethylene terephthalate (PET), polyimide (PI) or polyamideimide (PAI). The substrate 12 may also be a heat shrinkable material.

In another embodiment of the second type of structural adhesive paper, referring to FIG. 10 , the substrate 12 may also have an N-layer structure, where N is greater than or equal to 2. One surface of the sub-layer 121 of the substrate 12 close to the adhesive layer 11 (not shown) is pasted on the adhesive layer 11 , and the substrate 12 is far from the adhesive layer 11 and is at the outermost side of the substrate 12 . The outer surface S _t2 of the sub-layer 122 is subjected to surface treatment to obtain the surface S _t of the substrate 12 after the surface treatment. The surface-treated surface of the substrate 12 is obtained by applying silicone oil or fluorination to the outer surface S _t2 of the sub-layer 122 of the substrate 12 that is far from the adhesive layer 11 and is at the outermost side of the substrate 12 . S _t , so the material of the sub-layer 122 of the substrate 12 that is far from the adhesive layer 11 and is at the outermost side of the substrate 12 is not limited. Preferably, the material of the sub-layer 122 of the substrate 12 that is far from the adhesive layer 11 and is at the outermost side of the substrate 12 may be polyethylene terephthalate (PET), polyimide (PI) or Polyamideimide (PAI). The material of the sub-layer 122 of the substrate 12 that is far from the adhesive layer 11 and is at the outermost side of the substrate 12 may also be a heat-shrinkable material. The materials of the remaining sub-layers 121 are also not limited, and may preferably be polyethylene terephthalate (PET), polyimide (PI) or polyamideimide (PAI).

In the case where the base material 12 contains a heat-shrinkable material, when the structural tape 1 is heated, the heat-shrinkable material shrinks so that the structural tape 1 is curled from the opposite side edges in the width direction W to the middle portion, effectively controlling The curling direction of the structural adhesive tape 1; while the middle part of the structural adhesive tape 1 remains bonded to the bonded object 2 without peeling off, which can ensure an effective bonding area and prevent the structural tape 1 from being bonded from the bonded object during the heating process. 2 falls off. The heat shrinkable material may be polyvinyl chloride (PVC) heat shrinkable film, low molecular weight polyethylene terephthalate (PET) heat shrinkable film or biaxially oriented polyolefin (POF) heat shrinkable film. In the case where the substrate 12 includes a heat-shrinkable material, the thickness of the substrate 12 may be less than 45 μm. The thickness of the adhesive layer 11 is not limited, and preferably may be less than 10 μm.

In the second type of structural tape, the material of the adhesive layer 11 may be acrylic resin or polyurethane.

In the second type of structural tape, the adhesive layer 11 may contain a foaming agent. The particle diameter of the blowing agent may be less than 30 μm. When the adhesive layer 11 contains a foaming agent, it is required that the thickness of the adhesive layer 11 may be larger than the particle diameter of the foaming agent and smaller than 70 μm. The thickness of the substrate 12 is not limited, and preferably may be less than 30 μm.

In the second type of structural adhesive tape, the base material 12 can be a rectangle, which is convenient for subsequent welding of the tabs.

Claims (10)

1. A structural adhesive paper for adhering to an object to be adhered,

the dyne value of the outer surface of the structural adhesive paper opposite to the adhered object is 20 dyn/cm-28 dyn/cm;

the structural adhesive paper comprises:

an adhesive agent layer for adhering to an object to be adhered; and

a base material, one surface of which is adhered to the adhesive layer, and the other surface of which is subjected to surface treatment and which is used as the outer surface of the structural adhesive paper opposite to the adhered object; and is

The surface treatment is surface fluorination treatment.

2. The structural adhesive paper according to claim 1, wherein the substrate has a single-layer structure.

3. The structural adhesive paper according to claim 1, wherein the substrate has N sublayers, N being 2 or more;

one surface of the sublayer of the base material close to the adhesive layer is adhered to the adhesive layer, the outer surface of the sublayer of the base material, which is far away from the adhesive layer and is positioned at the outermost side of the base material, serves as the other surface of the base material, the other surface of the base material is subjected to surface treatment, and the surface subjected to surface treatment serves as the outer surface of the structural adhesive paper opposite to an adhered object.

4. The structural adhesive paper of claim 2, wherein the substrate is a polyfluoroolefin.

5. The structural adhesive paper according to claim 3, wherein the material of the sub-layer of the substrate which is far away from the adhesive layer and is located at the outermost side of the substrate is polyfluoroolefin.

6. The structural adhesive paper according to claim 2, wherein the substrate is polyethylene terephthalate, polyimide or polyamideimide, or the substrate is a heat-shrinkable material.

7. The structural adhesive paper as claimed in claim 3, wherein the material of the sub-layer of the substrate, which is far away from the adhesive layer and is located at the outermost side of the substrate, is polyethylene terephthalate, polyimide or polyamide imide, or the material of the sub-layer of the substrate, which is far away from the adhesive layer and is located at the outermost side of the substrate, is a heat-shrinkable material.

8. The structural adhesive paper according to claim 6 or 7, wherein the heat-shrinkable material is a polyvinyl chloride heat-shrinkable film, a low molecular weight polyethylene terephthalate heat-shrinkable film, or a biaxially oriented polyolefin heat-shrinkable film.

9. The structural adhesive paper according to claim 1, wherein the surface-treated region of the other surface of the base material is at least the entire peripheral portion of the other surface of the base material.

10. The structural adhesive paper according to claim 1, wherein the binder layer contains a foaming agent.

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