CN114714726B

CN114714726B - Aluminum plastic film and preparation method and application thereof

Info

Publication number: CN114714726B
Application number: CN202210154985.8A
Authority: CN
Inventors: 张潇; 夏旭峰; 雷中伟
Original assignee: Zhejiang Huazheng Energy Material Co ltd
Current assignee: Zhejiang Huazheng Energy Material Co ltd
Priority date: 2022-02-21
Filing date: 2022-02-21
Publication date: 2024-04-05
Anticipated expiration: 2042-02-21
Also published as: CN114714726A

Abstract

The invention belongs to the technical field of flexible packaging of lithium batteries, and particularly relates to an aluminum plastic film and a preparation method and application thereof. The aluminum plastic film comprises an SEBS modified nylon layer, an outer bonding layer, an outer anti-corrosion treatment layer, an aluminum foil layer, an inner anti-corrosion treatment layer, an inner bonding layer and a heat sealing layer which are sequentially overlapped from the outer side to the inner side, wherein the SEBS modified nylon layer comprises a nylon surface layer, a core layer and a corona layer which are sequentially overlapped from the outer side to the inner side, and SEBS is contained in the core layer and the corona layer. According to the invention, by combining the phenomenon that the aluminum plastic film is easy to warp towards the outer layer material after deep punching, the SEBS modified nylon film with low thermal expansion coefficient is adopted to reduce the thermal stress between the aluminum foil and the outer layer material after the processes of drying, compounding and curing, so that the warp is improved; in addition, through SEBS modified nylon core layer and second top layer corona layer, the impact toughness of outer layer material has been strengthened under a certain extent, and then the deep drawing shaping performance of plastic-aluminum membrane has been promoted.

Description

Aluminum plastic film and preparation method and application thereof

Technical Field

The invention belongs to the technical field of flexible packaging of lithium batteries, and particularly relates to an aluminum plastic film and a preparation method and application thereof.

Background

Lithium batteries are classified into prismatic batteries, pouch batteries, and cylindrical batteries. Because of the obvious advantages of the soft package battery in energy density, safety, module design flexibility and the like, the soft package battery has been widely used in the field of 3C consumer electronics, energy storage and power batteries. The aluminum plastic film is used as a key material for packaging the battery cells of the flexible package lithium battery, plays a role in protecting contents, and has strict requirements on barrier property, cold stamping formability, puncture resistance and the like.

The aluminum-plastic film is formed by compounding multiple layers of materials, and can be divided into a dry method aluminum-plastic film and a thermal method aluminum-plastic film according to different preparation processes. The dry-method aluminum-plastic film is formed by compounding an outer protective layer, an intermediate aluminum foil layer and an inner heat seal layer through an adhesive. The outer layer and the middle aluminum foil layer of the thermal aluminum-plastic film are compounded through an adhesive, and the inner heat sealing layer and the aluminum foil layer are bonded through a high-temperature bonding resin layer MPP. Because the inner layer and the outer layer of the aluminum plastic film are made of high polymer materials, and the middle aluminum foil layer is made of metal materials, compared with the thermal expansion coefficient of the metal materials, the thermal expansion coefficient of part of high polymer materials such as the outer nylon material and the inner CPP material is about 4-10 times of that of the metal materials. The difference between the thermal expansion coefficients of the layers is large, so that the aluminum plastic film is subjected to thermal stress caused by the drying and compounding and the curing process of glue along with the change of temperature, and is easy to cause curling deformation. Therefore, the manufactured aluminum-plastic composite film is easy to generate the problem of edge warpage in the deep drawing and forming process due to the existence of the stress and the thermal stress, and has certain influence on the efficiency and the yield of the packaging and liquid injection procedures on the production site.

The patent document with the application number of CN201910488640.4 discloses a deep-drawing low-warpage aluminum plastic film, wherein a polyamide film is added between an intermediate aluminum foil layer and an inner heat sealing layer of a conventional dry aluminum plastic film, and the purpose of preventing deep drawing warpage is achieved by utilizing the counteracting effect of stress of a first polyamide layer and a second polyamide layer in the deep drawing process, and different combinations and preparation methods of the layers. In addition, patent document with application number of CN201910627081.0 discloses an aluminum plastic film with low warpage and high heat sealing strength after deep drawing and a preparation method thereof, and the purpose of preventing deep drawing warpage is achieved by counteracting stress generated by a polyamide film by using stress generated in the deep drawing process of a high-strength cast polypropylene film layer. However, in the prior art, the warpage is counteracted and improved by stress action, and the difference of the thermal expansion coefficients of the composite materials is unavoidable, so that the thermal stress of the composite materials under the temperature change is influenced, and the depth of the drawing and the degree of the warpage are positively correlated. Accordingly, there is still a need in the art to further develop low warpage high draw down aluminum plastic films.

Disclosure of Invention

Based on the above-mentioned drawbacks and deficiencies of the prior art, it is an object of the present invention to at least solve one or more of the above-mentioned problems of the prior art, in other words, to provide an aluminium-plastic film satisfying one or more of the above-mentioned needs, and a method for preparing and using the same.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

the utility model provides an plastic-aluminum membrane, includes from outside to inboard superimposed nylon layer modified by SEBS, outer tie coat, outer anticorrosive treatment layer, aluminium foil layer, interior anticorrosive treatment layer, interior tie coat, heat seal layer in proper order, SEBS modified nylon layer includes from outside to inboard superimposed nylon surface layer, sandwich layer, corona layer in proper order, all contains the SEBS in sandwich layer and the corona layer.

Preferably, the nylon surface layer comprises 96-98 parts by mass of polyamide PA6 and 2-4 parts by mass of auxiliary agent.

Preferably, the core layer comprises 80-90 parts by mass of polyamide PA6 and 10-20 parts by mass of SEBS.

Preferably, the corona layer comprises 72-82 parts by mass of polyamide PA6, 15-25 parts by mass of SEBS and 2-4 parts by mass of auxiliary agent.

Preferably, the auxiliary agent comprises an opening agent and a slipping agent, the opening agent comprises at least one of fumed silica and precipitated silica, and the slipping agent comprises one or two of polysiloxane and modified polysiloxane.

As a preferable scheme, the thicknesses of the nylon surface layer, the core layer and the corona layer in the SEBS modified nylon layer are respectively 13-17%, 73-77% and 8-12%.

Preferably, the SEBS modified nylon layer has a thickness of 20-40 μm.

As a preferable scheme, the outer bonding layer and the inner bonding layer are both 3-5 mu m, the aluminum foil layer is 30-60 mu m, and the heat sealing layer is 30-80 mu m.

The invention also provides a preparation method of the aluminum plastic film according to any scheme, which comprises the following steps:

(1) Preparation of SEBS modified nylon layer

Respectively mixing the raw materials of the nylon surface layer, the core layer and the corona layer, respectively carrying out melt extrusion, converging and casting to a chill roll in a die head to obtain a cast sheet, and then sequentially carrying out longitudinal stretching, transverse stretching and corona treatment to obtain an SEBS modified biaxially oriented nylon film;

(2) Preparation of aluminium-plastic film

Carrying out double-sided anti-corrosion treatment on the aluminum foil layer to obtain an outer anti-corrosion treatment layer and an inner anti-corrosion treatment layer; and then respectively attaching an outer bonding layer and an inner bonding layer to the outer corrosion-resistant treatment layer and the inner corrosion-resistant treatment layer, and finally respectively compounding the SEBS modified biaxially oriented nylon film and the heat sealing layer with the outer bonding layer and the inner bonding layer to obtain the aluminum plastic film.

The invention also provides an application of the aluminum plastic film according to any scheme, which is characterized by being used as a lithium battery packaging material.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, by combining the phenomenon that the aluminum plastic film is easy to warp towards the outer layer material after deep punching, the SEBS modified nylon film with low thermal expansion coefficient is adopted to reduce the thermal stress between the aluminum foil and the outer layer material after the processes of drying, compounding and curing, so that the warp is improved; in addition, through SEBS modified nylon core layer and second top layer corona layer, the impact toughness of outer layer material has been strengthened under a certain extent, and then the deep drawing shaping performance of plastic-aluminum membrane has been promoted.

Drawings

FIG. 1 is a schematic structural diagram of an aluminum plastic film according to various embodiments of the present invention;

fig. 2 is a schematic view showing the warpage height of the aluminum plastic film after deep drawing.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention, specific embodiments of the present invention will be described below with reference to the accompanying drawings. It is evident that the drawings in the following description are only examples of the invention, from which other drawings and other embodiments can be obtained by a person skilled in the art without inventive effort.

Example 1:

as shown in fig. 1, the aluminum plastic film of the present embodiment comprises a SEBS (hydrogenated styrene-butadiene block copolymer, shell, kraton, FG 1901X) modified nylon layer 1, an outer tie layer 2, an outer corrosion-resistant treatment layer 3, an aluminum foil layer 4, an inner corrosion-resistant treatment layer 5, an inner tie layer 6, and a heat seal layer 7, which are laminated in this order from the outside to the inside.

The SEBS modified nylon layer comprises a nylon surface layer (called A layer for short), a core layer (called B layer for short) and a corona layer (called C layer for short) which are sequentially overlapped from the outer side to the inner side.

Specifically, the preparation method of the aluminum plastic film comprises the following steps:

(1) Preparation of SEBS modified nylon layer

Weighing a layer A comprising 97 parts by mass of polyamide PA6 and 3 parts by mass of auxiliary agent, a layer B comprising 90 parts by mass of polyamide PA6 and 10 parts by mass of SEBS, and a layer C comprising 87 parts by mass of polyamide PA6, 10 parts by mass of SEBS and 3 parts by mass of auxiliary agent; and mixing the materials of each layer by a high-speed mixer to uniformly disperse the materials, adding the materials into three extruders to melt, converging and casting the materials in a die head to a chill roll to obtain a cast sheet, and forming the SEBS modified biaxially oriented nylon film with low thermal expansion coefficient by longitudinal stretching, transverse stretching and corona treatment.

Wherein the total thickness is controlled to be (25+/-1) mu m, the A layer accounts for 15 percent, the B layer accounts for 75 percent, and the C layer accounts for 10 percent.

(2) Preparation of aluminium-plastic film

Carrying out double-sided corrosion prevention treatment on the aluminum foil layer 4 to obtain an outer corrosion prevention treatment layer 3 and an inner corrosion prevention treatment layer 5; and then the outer adhesive layer 2 and the inner adhesive layer 6 are respectively attached to the outer anti-corrosion treatment layer 3 and the inner anti-corrosion treatment layer 5, and finally the SEBS modified biaxially oriented nylon film 1 and the heat sealing layer 7 are respectively compounded with the outer adhesive layer 2 and the inner adhesive layer 6 to obtain the aluminum plastic film.

The aluminum plastic film of the embodiment is used as a lithium battery packaging material.

Example 2:

the aluminum plastic film of this embodiment is different from embodiment 1 in that: the SEBS modified nylon layers are different.

Specifically, the preparation of the SEBS modified nylon layer of this example includes:

weighing a layer A comprising 97 parts by mass of polyamide PA6 and 3 parts by mass of auxiliary agent, a layer B comprising 85 parts by mass of polyamide PA6 and 15 parts by mass of SEBS, and a layer C comprising 82 parts by mass of polyamide PA6, 15 parts by mass of SEBS and 3 parts by mass of auxiliary agent; and mixing the materials of each layer by a high-speed mixer to uniformly disperse the materials, adding the materials into three extruders to melt, converging and casting the materials in a die head to a chill roll to obtain a cast sheet, and forming the SEBS modified biaxially oriented nylon film with low thermal expansion coefficient by longitudinal stretching, transverse stretching and corona treatment.

Wherein, the total thickness is controlled to be (25+/-1) mu m, the A layer accounts for 15 percent, the B layer accounts for 75 percent and the C layer accounts for 10 percent.

Otherwise, the same as in example 1 was conducted.

Example 3:

weighing a layer A comprising 97 parts by mass of polyamide PA6 and 3 parts by mass of auxiliary agent, a layer B comprising 85 parts by mass of polyamide PA6 and 15 parts by mass of SEBS, and a layer C comprising 77 parts by mass of polyamide PA6, 20 parts by mass of SEBS and 3 parts by mass of auxiliary agent; and mixing the materials of all layers by a high-speed mixer to uniformly disperse the materials, adding the materials into three extruders to melt, converging and casting the materials in a die head to a chill roll to obtain a cast sheet, and forming the SEBS modified biaxially oriented nylon film 3 with low thermal expansion coefficient by longitudinal stretching, transverse stretching and corona treatment.

Example 4:

weighing a layer A comprising 97 parts by mass of polyamide PA6 and 3 parts by mass of auxiliary agent, a layer B comprising 80 parts by mass of polyamide PA6 and 20 parts by mass of SEBS, and a layer C comprising 72 parts by mass of polyamide PA6, 25 parts by mass of SEBS and 3 parts by mass of auxiliary agent; and mixing the materials of all layers by a high-speed mixer to uniformly disperse the materials, adding the materials into three extruders to melt, converging and casting the materials in a die head to a chill roll to obtain a cast sheet, and forming the SEBS modified biaxially oriented nylon film 3 with low thermal expansion coefficient by longitudinal stretching, transverse stretching and corona treatment.

Comparative example 1:

the aluminum plastic film of this comparative example is different from example 1 in that: the SEBS modified nylon layers are different.

Specifically, the preparation of the SEBS modified nylon layer of this comparative example includes:

the layer A and the layer C are weighed to comprise 97 parts by mass of polyamide PA6 and 3 parts by mass of auxiliary agent, and the layer B is polyamide PA6. And mixing the materials of each layer by a high-speed mixer to uniformly disperse the materials, adding the materials into three extruders to melt, merging and casting the materials in a die head to a chill roll to obtain a cast sheet, and forming a conventional biaxially oriented nylon film by longitudinal stretching, transverse stretching and corona treatment.

In contrast to the SEBS-modified biaxially oriented nylon film of low thermal expansion coefficient, comparative example 1 did not incorporate SEBS.

Comparative example 2:

the aluminum plastic film of this comparative example is different from example 1 in that: the SEBS modified nylon layer was replaced with a commercially available 25 μm biaxially oriented polyamide nylon film.

In addition, in examples 1 to 4 and comparative examples 1 to 2 described above:

the outer bonding layer is a commercially available polyurethane adhesive for the double-component aluminum-plastic film compounding, and the thickness is 3 mu m; the inner and outer anticorrosive treatment layers are anticorrosive layers treated by trivalent chromium passivating agents; the aluminum foil layer is O-state 8021 aluminum foil with the thickness of 40 μm; the inner bonding layer is a commercially available modified polyolefin resin for compounding the double-component aluminum plastic film and an isocyanate curing agent adhesive, and the thickness is 3 mu m; the heat-seal layer was a commercially available maleic anhydride modified cast polypropylene film (CPP) 40 μm thick.

The performance of the aluminum plastic films of examples 1 to 4 and comparative examples 1 to 2 was tested as follows.

1. And (3) deep drawing limit test of the aluminum plastic film: the aluminum plastic film is subjected to humidity adjustment for more than 24 hours at the temperature of 23+/-2 ℃ and the RH environment of 50+/-10%, the die model is 104050, the R angle is 1.5 degrees, the aluminum plastic film is punched under the pressure of 0.6MPa, the appearance of a sample is checked, and the punching depth is measured by a measuring tool with the precision of 0.01 mm.

2. Warpage of aluminum plastic films: the aluminum plastic film is subjected to humidity adjustment for more than 24 hours at the temperature of 23+/-2 ℃ and the RH environment of 50+/-10%, the die model is 104050, the R angle is 1.5 degrees, the aluminum plastic film is punched under the pressure of 0.6MPa, the warping height of the rear edge of the 4-angle punching depth at the depth of 7.0mm is measured, as shown in figure 2, and the total warping height of four angles is counted.

Table 1 performance test parameters of the plastic-aluminum films of each example and comparative example

Sample preparation	Depth limit per mm	Total warp height/mm
			Example 1	7.0	90.5
Example 2	7.5	77.4
			Example 3	7.8	56.6
Example 4	7.0	63.8
			Comparative example 1	6.7	114.9
Comparative example 2	7.0	106.3

Based on the comparison of the performance tests, the invention can be found that the SEBS is introduced into the nylon layer to prepare the SEBS modified nylon film with low expansion coefficient so as to reduce the thermal stress between the aluminum foil and the outer layer material after the procedures of drying, compounding and curing, thereby improving the warping condition of the aluminum plastic film after deep punching; when the SEBS content is introduced to be more than 15%, the warping condition starts to be obviously improved; the subsequent continuous increase of the SEBS content can lead to insufficient strength of the nylon layer and further influence the deep drawing forming performance of the aluminum plastic film. Therefore, due to the introduction of a proper amount of SEBS with low modulus and good toughness, and the formation of a gradient in the contents of the A layer, the B layer and the C layer, the warping condition of the aluminum plastic film after deep drawing and the deep drawing forming performance of the aluminum plastic film can be obviously improved.

Therefore, the aluminum plastic film prepared by the invention has the advantages of low deep drawing warp phenomenon and good deep drawing forming performance.

The foregoing is only illustrative of the preferred embodiments and principles of the present invention, and changes in specific embodiments will occur to those skilled in the art upon consideration of the teachings provided herein, and such changes are intended to be included within the scope of the invention as defined by the claims.

Claims

1. The aluminum plastic film is characterized by comprising an SEBS modified nylon layer, an outer bonding layer, an outer anti-corrosion treatment layer, an aluminum foil layer, an inner anti-corrosion treatment layer, an inner bonding layer and a heat sealing layer which are sequentially overlapped from the outer side to the inner side, wherein the SEBS modified nylon layer comprises a nylon surface layer, a core layer and a corona layer which are sequentially overlapped from the outer side to the inner side, and the core layer and the corona layer both contain SEBS; wherein the thickness of the external bonding layer is 3 mu m; the inner and outer anticorrosive treatment layers are anticorrosive layers treated by trivalent chromium passivating agents; the aluminum foil layer is O-state 8021 aluminum foil with the thickness of 40 μm; the thickness of the inner bonding layer is 3 mu m; the thickness of the heat seal layer is 40 mu m;

the preparation method of the aluminum plastic film comprises the following steps:

(1) Preparation of SEBS modified nylon layer

Weighing a nylon surface layer which comprises 97 parts by mass of polyamide PA6 and 3 parts by mass of auxiliary agent, a core layer which comprises 85 parts by mass of polyamide PA6 and 15 parts by mass of SEBS, and a corona layer which comprises 77 parts by mass of polyamide PA6, 20 parts by mass of SEBS and 3 parts by mass of auxiliary agent; mixing the materials of each layer by a high-speed mixer to uniformly disperse the materials, adding the materials into three extruders to melt, converging and casting the materials in a die head to a chill roll to obtain a cast sheet, and forming an SEBS modified biaxially oriented nylon film with low thermal expansion coefficient by longitudinal stretching, transverse stretching and corona treatment; wherein, the total thickness of the SEBS modified nylon layer is controlled to be 25+/-1 mu m, the nylon surface layer accounts for 15 percent, the core layer accounts for 75 percent, and the corona layer accounts for 10 percent;

(2) Preparation of aluminium-plastic film

2. Use of an aluminium-plastic film according to claim 1 as a lithium battery packaging material.