WO2018133030A1 - Tab sealant - Google Patents

Tab sealant Download PDF

Info

Publication number
WO2018133030A1
WO2018133030A1 PCT/CN2017/071918 CN2017071918W WO2018133030A1 WO 2018133030 A1 WO2018133030 A1 WO 2018133030A1 CN 2017071918 W CN2017071918 W CN 2017071918W WO 2018133030 A1 WO2018133030 A1 WO 2018133030A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
comonomer
tab sealant
monomer
polyolefin
Prior art date
Application number
PCT/CN2017/071918
Other languages
French (fr)
Inventor
Changsheng Liang
Tylor ZHOU
Xinhui Zhang
Original Assignee
Avery Dennison Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Avery Dennison Corporation filed Critical Avery Dennison Corporation
Priority to PCT/CN2017/071918 priority Critical patent/WO2018133030A1/en
Priority to TW106146596A priority patent/TWI655280B/en
Priority to CN201810048542.4A priority patent/CN108274869A/en
Publication of WO2018133030A1 publication Critical patent/WO2018133030A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/183—Sealing members
    • H01M50/186—Sealing members characterised by the disposition of the sealing members
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B23/00—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose
    • B32B23/04—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B23/08—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B32B27/281—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polyimides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B32B27/285—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polyethers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B32B27/286—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polysulphones; polysulfides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/302—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/304—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/308—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/322—Layered products comprising a layer of synthetic resin comprising polyolefins comprising halogenated polyolefins, e.g. PTFE
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/027—Thermal properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/183—Sealing members
    • H01M50/19—Sealing members characterised by the material
    • H01M50/193—Organic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/183—Sealing members
    • H01M50/19—Sealing members characterised by the material
    • H01M50/197—Sealing members characterised by the material having a layered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/183—Sealing members
    • H01M50/19—Sealing members characterised by the material
    • H01M50/198—Sealing members characterised by the material characterised by physical properties, e.g. adhesiveness or hardness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/03—3 layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B32B2250/242—All polymers belonging to those covered by group B32B27/32
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
    • B32B2307/206—Insulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/54—Yield strength; Tensile strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/546—Flexural strength; Flexion stiffness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/714—Inert, i.e. inert to chemical degradation, corrosion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/732—Dimensional properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/748—Releasability
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/10—Batteries
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2581/00—Seals; Sealing equipment; Gaskets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/172—Arrangements of electric connectors penetrating the casing
    • H01M50/174—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells
    • H01M50/178—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells for pouch or flexible bag cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates generally to tab sealants.
  • the tab sealants comprise three layers and in particular, at least one of the first and third layer contains a base polymer grafted with a monomer and comonomer comprising a benzene ring.
  • Tab sealants also referred to as terminal covering resin films, are generally used for covering tabs in battery cells.
  • the tabs have metal leads serving as a metal terminal and the tabs serve as electrode terminals to which electric power is supplied to a cell body.
  • Tab sealants desirably have good adhesion between the tab sealant and the metal lead to prevent peeling off of the tab sealant.
  • Tab sealants also desirably secure insulation of the lead with other parts of the cell body.
  • tab sealants desirably have good corrosion resistance.
  • US Pat. No. 7,972,722 discloses a lead sealant film and a non-aqueous electrolyte battery.
  • the lead sealant film includes a laminated structure composed of an inner layer, an intermediate layer, and an outer layer.
  • the intermediate layer includes a first acid-modified polypropylene having a high melting-point
  • each of the inner layer and the outer layer includes a second acid-modified polypropylene having a low melting-point.
  • a difference between the melting point of the first acid-modified polypropylene and the melting point of the second acid-modified polypropylene is from 20°C to 25°C.
  • US Pat. No. 9,123,922 discloses a lithium ion battery exterior material, including a base material layer and a sequentially laminated adhesive layer, aluminum foil layer provided with a corrosion prevention treated layer, and an adhesive resin layer on one surface of the base material layer; wherein, the adhesive resin layer contains an acid-modified polyolefin resin and a miscible elastomer dispersed in the acid-modified polyolefin at a dispersed phase size of 1 nm to less than 1 ⁇ m.
  • US Pub. No. 2010/0221601 discloses an electrical part comprising a lead conductor and a sealed vessel including a metal layer, the lead conductor extending from the inside of the sealed vessel to the outside, wherein the lead conductor and the sealed vessel are fusion-bonded through a thermal adhesive layer at the sealing portion, and wherein a softening-resistant layer having through holes made in the thickness direction is provided between the lead conductor and the metal layer at the sealing portion.
  • a nonaqueous electrolyte cell comprising an electrode and a nonaqueous electrolyte are both enclosed inside the sealed vessel. Both the sealed vessel and a lead conductor having an insulating coating layer can be used in the electrical part or the like.
  • US Pub. No. 2015/0311483 discloses a secondary battery metal terminal coating resin film having improved overall performance. It is capable of securing filling ability, adhesive properties, insulating properties of a lead end portion, and shape retention properties of a sealant. Also disclosed is a manufacturing method for the same. Also disclosed is a battery pack using the secondary battery metal terminal coating resin film provided in the lead end portion of a tab used for a laminate-type packaging material for a secondary battery. The secondary battery metal terminal coating resin film is laminated and a coating metal terminal is connected to a positive electrode or a negative electrode of a secondary battery. The melt flow rate of at least one layer of a resin that constitutes the resin film is within a range from about 0.1 g/10 minutes to about 2.5 g/10 minutes.
  • US Pub. No. 2016/0099446 discloses a resin film, which is adapted for use in a packaging material for secondary cell.
  • the secondary cell has a sealant layer formed of a polyolefin resin.
  • the resin film is disposed between the sealant layer and leads that are connected to a positive electrode and a negative electrode.
  • the layer includes a first layer disposed at a position close to the leads and a second layer disposed at a position close to the sealant layer.
  • a heat quantity of the second layer measured according to JIS K 7122, is larger than a heat quantity of fusion of the first layer.
  • US Pub. No. 2016/0099447 discloses a terminal covering resin film for a secondary cell, which is attached so as to cover part of an outer surface of a terminal connected to a power generation element of a secondary cell.
  • the film comprises an innermost layer contacting the terminal and an outermost layer forming a surface opposite to the innermost layer, wherein the innermost layer is a layer of not less than 20 ⁇ m in thickness containing an acid-modified polyolefin and a melt flow rate of the innermost layer is not less than 2.0 g/10 minutes.
  • JP 2016091939 discloses tensile storage modulus, dynamic viscoelasticity and melt flow rate values for a resin film.
  • the invention relates to a tab sealant comprising: (a) a first layer comprising a polyolefin grafted with a monomer; (b) a second layer comprising a polyolefin; and (c) a third layer comprising a polyolefin grafted with a monomer; wherein the second layer is disposed between the first layer and the third layer, and further wherein the polyolefin in at least one of the first layer and the third layer is grafted with a monomer and a comonomer containing a benzene ring.
  • the polyolefin of the first layer, second layer, and third layer may be independently selected from the group consisting of homo polypropylene, block polypropylene, and random polypropylene.
  • the monomer in the first layer and/or the third layer may be selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, ⁇ -methacrylic acid, methyl methacrylate, and glycidyl methacrylate.
  • the polyolefin in the first layer may be grafted with the monomer and a comonomer.
  • the polyolefin in the third layer may be grafted with the monomer and a comonomer.
  • the polyolefin in the first layer and the third layer may be grafted with the monomer and a comonomer.
  • the comonomer in the first layer is different than the comonomer in the second layer.
  • the comonomer in the first layer is the same as the comonomer in the second layer.
  • the comonomer may be selected from the group consisting of styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and ⁇ -methylstyrene.
  • the monomer may be present in the first layer from 1 to 20 wt. %.
  • the comonomer may be present in the first layer from 1 to 10 wt. %.
  • the monomer may be present in the third layer from 1 to 20 wt. %.
  • the comonomer may be present in the third layer from 1 to 10 wt. %.
  • the first layer and third layer may have substantially the same composition.
  • the thickness of the first layer may be from 1 to 50 ⁇ m.
  • the thickness of the second layer may be from 30 to 100 ⁇ m.
  • the first layer may have a melting point from 130 to 160°C.
  • the second layer may have a melting point from 130 to 190°C.
  • the third layer may have a melting point from 130 to 160°C.
  • the first layer may have a melt flow rate of 2 to 20 g/10 min.
  • the second layer may have a melt flow rate of 2 to 20 g/10 min.
  • the third layer may have a melt flow rate of 2 to 20 g/10 min.
  • the first layer may further comprise an additive.
  • FIG. 1 shows a perspective view of a cell pack in accordance with aspects of the invention
  • FIG. 2 shows a perspective view of a tab in accordance with aspects of the invention.
  • FIG. 3 shows a cross-sectional view of a tab sealant in accordance with aspects of the invention.
  • the present invention is directed to tab sealants that have superior adhesion, insulation, and corrosion resistance as compared to conventional tab sealants.
  • the tab sealant according to the present invention is a three layer film.
  • the first and third layers each (individually) comprise a polyolefin grafted with a monomer.
  • the second layer comprises a polyolefin.
  • the polyolefin is grafted with the monomer and with a comonomer comprising a benzene ring.
  • the first layer comprises a polyolefin grafted with a monomer and a comonomer comprising a benzene ring, also referred to as a benzene ring comonomer.
  • the third layer comprises a polyolefin grafted with a monomer and a benzene ring comonomer.
  • both the first layer and the third layer comprise a polyolefin grafted with a monomer and a benzene ring comonomer, and the composition of the first layer and third layer may be substantially the same.
  • the overall compositions of the first and third layers may vary widely (as long as the benzene ring comonomer is included in at least one of the layers) .
  • the base polymer may be the same in each layer while the monomer and/or inclusion of a comonomer may differ.
  • Further embodiments may include the same monomer in each layer but with a different base polymer.
  • the base polymer, monomer, and optional comonomer may be the same, but the weight percentages and/or molecular weights of each component may differ between the first and third layer.
  • FIG. 1 illustrates a cell pack 10 comprising a cell body 11, packaging material 12, tabs 13 and 14, lead 15, and tab sealant 16.
  • FIG. 2 shows tab 13 with a lead 15 serving as a metal terminal, and tab sealant 16.
  • the lead 15 has a first end portion 15A electrically connected to a power generation element inside of packaging material 12 (shown in FIG. 1) , and a second end portion 15B which is electrically conductive and which has an outer surface that is at least partially exposed to permit connection with an external device to which electric power may be supplied.
  • FIG. 3 shows a cross-sectional view of tab sealant 16.
  • tab sealant 16 contains a first layer 17 (an inner layer) , a second layer 18 (an intermediate layer) , and a third layer 19 (an outer layer) .
  • first layer 17 an inner layer
  • second layer 18 an intermediate layer
  • third layer 19 an outer layer
  • the tab sealant may be prepared by a co-extrusion casting process, a co-extrusion blowing process, or other processes known in the art.
  • the first, second, and third layer may be co-extruded together in a three-layer co-extrusion machine.
  • the processing temperature may depend on the tab sealant components. Generally, the processing temperature is in the range of 230 to 250°C.
  • the first layer 17, also referred to as an inner layer, is the layer which seals the outer surface of the lead 15 and is therefore in contact with the outer surface of the lead.
  • the first layer may be comprised of a base polymer grafted with a monomer.
  • the base polymer may be an olefin polymer.
  • the olefin polymer may include, but is not limited to, polyethylene, including low, medium and high density polyethylenes; polypropylene, including homo, block or random polypropylene; polymethylpentene, polybutene-1; and ethylene- ⁇ -olefin copolymers.
  • the olefin polymer is polypropylene.
  • the base polymer may be grafted with a monomer.
  • the monomer may include, but is not limited to acrylic acid, methacrylic acid, maleic acid, and maleic anhydride, ⁇ -methacrylic acid, methyl methacrylate, and glycidyl methacrylate. In some aspects, the monomer is maleic anhydride.
  • the base polymer in the first layer may also be grafted with a comonomer, e.g., a monomer containing a benzene ring.
  • a comonomer e.g., a monomer containing a benzene ring.
  • the comonomer may be an olefin monomer containing a benzene ring, such as styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and ⁇ -methylstyrene.
  • the inventors have now discovered that by including a comonomer with a benzene ring when grafting the base polymer and monomer, the grafting reaction rate is surprisingly increased, resulting in improved adhesion of the tab sealant. Additionally, the inclusion of a comonomer with a benzene ring when grafting the base polymer and monomer has been found to unexpectedly improve corrosion resistance of the base polymer, e.g., polypropylene.
  • the base polymer may be present in the first layer in an amount from to 70 to 98 wt. %, based on the entire weight of the first layer, e.g., from 78.5 to 96.5 wt. %or from 85 to 95 wt. %.
  • the first layer comprises at least 70 wt. % base polymer, based on the entire weight of the first layer, e.g., at least 78.5 wt. %or at least 85 wt. %.
  • the first layer comprises no more than 98 wt. % base polymer, based on the entire weight of the first layer, e.g., no more than 96.5 wt. % or no more than 95 wt. %.
  • the monomer may be present in the first layer in an amount from 1 to 20 wt.%, e.g., from 2 to 15 wt. %or from 3 to 10 wt. %, based on the entire weight of the first layer.
  • the first layer comprises at least 1 wt. %monomer, based on the entire weight of the first layer, e.g., at least 2 wt. %or at least 3 wt. %.
  • the first layer comprises no more than 20 wt. %monomer, based on the entire weight of the first layer, e.g., no more than 15 wt. %or no more than 10 wt. %.
  • the first layer may comprise from 1 to 10 wt.%comonomer, based on the entire weight of the first layer, e.g., from 1.5 to 7.5 wt. % or from 2 to 5 wt. %.
  • the first layer comprises at least 1 wt. % comonomer, based on the entire weight of the first layer, e.g., at least 1.5 wt. %or at least 2 wt. %.
  • the first layer comprises no more than 20 wt. % monomer, based on the entire weight of the first layer, e.g., no more than 15 wt. %or no more than 10 wt. %.
  • the first layer may comprise an additive.
  • the additive may be present from 1 to 15 wt. %, based on the entire weight of the first layer, e.g., from 1 to 12 wt. %or from 1 to 10 wt. %.
  • Additives known in the art may be included, such as antioxidants.
  • the first layer may be thinner than those of conventional tab sealants.
  • the first layer has a thickness ranging from 1 to 50 microns, e.g., from 5 to 25 microns, or from 10 to 20 microns. In terms of lower limits, the first layer may have a thickness of at least 1 micron, e.g., at least 5 microns, or at least 10 microns. It has now been discovered that a thinner first layer may lead to improved corrosion resistance as compared to a thicker first layer. In some cases, the thickness of the first layer may be selected based on the desired corrosion resistance. Without being bound by theory, it is believed that the existence of the polar groups in the first (and/or third layer) reduce corrosion resistance.
  • the second layer may not contain polar groups, its corrosion resistance is better as compared to the first and/or third layer. Therefore, by having a thinner first layer (and/or third layer) , the impact of the first (and/or third layer) on the corrosion resistance of the tab sealant is reduced.
  • the first layer may have a melting point from 130 to 160°C, e.g., from 130 to 150°C, or from 130 to 140°C. In terms of lower limits, the first layer may have a melting point of at least 130°C, e.g., at least 133°C or at least 135°C . In terms of upper limits, the first layer may have a melting point no greater than 160°C, e.g., no greater than 150°C or 140°C. A melting point below 130°C may not provide satisfactory heat resistance while a melting point above 160°C may require too much heat to seal the first layer to the lead, resulting in decreased adhesion and insulation.
  • the melt flow rate of the first layer may range from 2 to 20 g/10 minutes, e.g., from 3 to 10 g/10 minutes or from 5 to 6 g/10 minutes. In terms of lower limits, the first layer may have a melt flow rate of at least 2 g/10 minutes, e.g., at least 3 g/10 minutes or at least 5 g/10 minutes. In terms of upper limits, the first layer may have a melt flow rate of no greater than 20 g/10 minutes, e.g., no greater than 10 g/10 minutes or no greater than 6 g/10 minutes.
  • the melt flow rate is an index showing the fluidity of the layer during heating. If the melt flow rate is less than 2 g/10 minutes, sealing of the tab sealant around the lead may be insufficient due to reduced fluidity. If the melt flow rate is greater than 20 g/10 minutes, the first layer may flow too easily, resulting in thinning of the layer during sealing.
  • the second layer 18 may also be referred to as an intermediate layer, and is disposed between the first layer 17 and third layer 19 of the tab sealant.
  • the second layer may be comprised of a polyolefin.
  • the polyolefin film may vary widely.
  • the polyolefin may include polyethylene, including low, medium and high density polyethylenes; polypropylene, including homo, block or random polypropylene; polymethylpentene, polybutene-1; and ethylene- ⁇ -olefin copolymers.
  • the olefin polymer is polypropylene, and may be a casting polypropylene film.
  • the polyolefin film may comprise any polyolefin material that exhibits good mechanical strength and heat resistance.
  • Exemplary polyolefin films may comprise at least one of a polyimide, a polyester, a polyetherimide (PEI) , a polyethylene naphthalate (PEN) , a polyether sulfone (PES) , a polysulfone, polymethylpentene (PMP) , a polyvinylidene fluoride (PVDF) , an ethylene-chlorotrifluoroethylene (ECTFE) , or combinations thereof.
  • the polyolefin in the second layer may be the same polyolefin as in the first layer, though the molecular weight and/or melting point may differ.
  • Exemplary polyolefin films made of polyimide include available from DuPont, and available from Kaneka Texas Corporation, Exemplary polyolefin films made of polyester include avai lable from DuPont, and 2600 polyethylene terephthalate film, available from American Hoechst.
  • Other commercially available polyolefin films include Tempalux TM (PEI) , available from Westlake Plastics Company; Superio-UT TM (PEI) , available from Mitsubishi Plastics, Kaladex TM ; (PEN) and Teonex (PEN) , both available from DuPont.
  • the second layer may be thicker than the first layer and/or third layer.
  • the second layer may be at least 10%thicker, e.g., at least 20%thicker, at least 30%thicker, or at least 40%thicker than at least one of the first and third layer.
  • the second layer may have a thickness ranging from 30 to 100 microns, e.g., from 45 to 90 microns or from 60 to 80 microns.
  • the second layer may have a thickness of at least 30 microns, e.g., at least 45 microns, or at least 60 micros.
  • the second layer may have a thickness of no more than 100 microns, e.g., no more than 90 microns or no more than 80 microns.
  • the second layer may have a melting point from 130 to 190°C, e.g., from 140 to 180°C, or from 150 to 170°C. In terms of lower limits, the second layer may have a melting point of at least 130°C, e.g., at least 140°C or at least 150°C . In terms of upper limits, the second layer may have a melting point no greater than 190°C, e.g., no greater than 180°C or 170°C. As compared to at least one of the first and third layer, the melting point of the second layer may be at least 10°C greater, e.g., at least 20°C greater or at least 30°C greater.
  • the melt flow rate of the second layer may range from 2 to 20 g/10 minutes, e.g., from 5 to 10 g/10 minutes or from 7 to 9 g/10 minutes. In terms of lower limits, the second layer may have a melt flow rate of at least 2 g/10 minutes, e.g., at least 5 g/10 minutes or at least 7 g/10 minutes. In terms of upper limits, the second layer may have a melt flow rate of no greater than 20 g/10 minutes, e.g., no greater than 10 g/10 minutes or no greater than 9 g/10 minutes.
  • the tensile strength and flexural modulus of the second layer may be selected based on the desired heat and moisture resistance of the layer, since the second layer provides insulation for the tab sealant.
  • the tensile strength at yield ranges from 25 to 35 MPa, e.g., from 28 to 34 MPa or from 30 to 32 MPa.
  • the flexural modulus may range from 800 to 1500 MPa, e.g., from 900 to 1450 MPa or from 1100 to 1400 MPa.
  • the third layer 19 also referred to as an outer layer, is in contact with the second layer 18.
  • the third layer may be the same, substantially the same, or different than the first layer.
  • the third layer may be comprised of a base polymer grafted with a monomer.
  • the base polymer may be an olefin polymer.
  • the olefin polymer may include, but is not limited to, polyethylene, including low, medium and high density polyethylenes; polypropylene, including homo, block or random polypropylene; polymethylpentene, polybutene-1; and ethylene- ⁇ -olefin copolymers.
  • the olefin polymer is polypropylene.
  • the base polymer may be grafted with a monomer.
  • the monomer may include, but is not limited to acrylic acid, methacrylic acid, maleic acid, maleic anhydride, ⁇ -methacrylic acid, methyl methacrylate, and glycidyl methacrylate. In some aspects, the monomer is maleic anhydride.
  • the base polymer in the third layer may also be grafted with a comonomer, e.g., a monomer containing a benzene ring.
  • the comonomer may be an olefin monomer containing a benzene ring, such as styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and ⁇ -methylstyrene.
  • the base polymer may be present in the third layer in an amount from to 70 to 98 wt. %, based on the entire weight of the third layer, e.g., from 78.5 to 96.5 wt. %or from 85 to 95 wt. %.
  • the third layer comprises at least 70 wt. % base polymer, based on the entire weight of the third layer, e.g., at least 78.5 wt. %or at least 85 wt. %.
  • the third layer comprises no more than 98 wt. % base polymer, based on the entire weight of the third layer, e.g., no more than 96.5 wt.%or no more than 95 wt.
  • the base polymer in the third layer may be the same base polymer as in the first layer, or it may be substantially the same due to differences in melting point or molecular weight. In some aspects, a different base polymer is used in the third layer as compared to the first layer. In further aspects, the base polymer in the third layer may be the same as the polyolefin in the second layer or it may be substantially the same due to differences in melting point or molecular weight. In still further aspects, a different base polymer is used in the third layer as compared to the polyolefin in the second layer.
  • the monomer may be present in the third layer in an amount from 1 to 20 wt.%, e.g., from 2 to 15 wt. %or from 3 to 10 wt. %, based on the entire weight of the third layer.
  • the third layer comprises at least 1 wt. %monomer, based on the entire weight of the third layer, e.g., at least 2 wt. %or at least 3 wt. %.
  • the third layer comprises no more than 20 wt. %monomer, based on the entire weight of the third layer, e.g., no more than 15 wt. %or no more than 10 wt.%.
  • the monomer polymer in the third layer may be the same monomer as in the first layer, or it may be substantially the same due to differences in melting point or molecular weight. In some aspects, a different monomer is used in the third layer as compared to the first layer.
  • the third layer may comprise from 1 to 10 wt.%comonomer, based on the entire weight of the third layer, e.g., from 1.5 to 7.5 wt.%or from 2 to 5 wt. %. In terms of lower limits, the third layer comprises at least 1 wt.%comonomer, based on the entire weight of the third layer, e.g., at least 1.5 wt. %or at least 2 wt. %. In terms of upper limits, the third layer comprises no more than 20 wt. % monomer, based on the entire weight of the third layer, e.g., no more than 15 wt. %or no more than 10 wt. %.
  • the comonomer in the third layer may be the same comonomer as in the first layer, or it may be substantially the same due to differences in melting point or molecular weight. In some aspects, a different comonomer is used in the third layer as compared to the first layer.
  • the third layer may comprise an additive.
  • the additive may be present from 1 to 15 wt. %, based on the entire weight of the third layer, e.g., from 1 to 12 wt. %or from 1 to 10 wt. %.
  • Additives known in the art may be included, such as antioxidants.
  • the third layer may have a thickness ranging from 1 to 50 microns, e.g., from 5 to 25 microns, or from 10 to 20 microns. In terms of lower limits, the third layer may have a thickness of at least 1 micron, e.g., at least 5 microns, or at least 10 micros.
  • the thickness of the third layer may be selected based on the desired corrosion resistance. Without being bound by theory, it is believed that a thinner first layer leads to improved corrosion resistance as compared to a thicker first layer.
  • the thickness of the third layer may be the as the first layer, or it may be different. In some aspects, the thickness of the third layer is within ⁇ 30%of the thickness of the first layer, e.g., within ⁇ 20%or ⁇ 10%.
  • the total thickness of the first and third layer combined may range from 2 to 100 microns, e.g., from 10 to 80 microns, or from 20 to 40 microns.
  • the total thickness of the first layer, second layer, and third layer, combined may range from 32 to 200 microns, e.g., from 55 to 190 microns, or from 80 to 120 microns.
  • the third layer may have a melting point from 130 to 160°C, e.g., from 130 to 150°C, or from 130 to 140°C. In terms of lower limits, the third layer may have a melting point of at least 130°C, e.g., at least 133°C or at least 135°C. In terms of upper limits, the first layer may have a melting point no greater than 160°C, e.g., no greater than
  • the melting point of the third layer is within 10°C of the melting point of the first layer, e.g., within 5°C or within 3°C. In further aspects, the melting point of the third layer is within 40°C of the melting point of the first layer, e.g., within 35°C or within 30°C.
  • the melt flow rate of the third layer may range from 2 to 20 g/10 minutes, e.g., from 3 to 10 g/10 minutes or from 5 to 6 g/10 minutes. In terms of lower limits, the third layer may have a melt flow rate of at least 2 g/10 minutes, e.g., at least 3 g/10 minutes or at least 5 g/10 minutes. In terms of upper limits, the third layer may have a melt flow rate of no greater than 20 g/10 minutes, e.g., no greater than 10 g/10 minutes or no greater than 6 g/10 minutes. In some aspects, the melt flow rate of the third layer is within 3 g/10 minutes of the melt flow rate of the first layer, e.g., within 2 g/10 minutes or within 1 g/10 minutes. In some aspects, the melt flow rate of the third layer may be within 5 g/10 minutes of the melt flow rate of the second layer, e.g., within 4 g/10 minutes or within 3 g/10 minutes.
  • Embodiment 1 A tab sealant comprising: (a) a first layer comprising a polyolefin grafted with a monomer; (b) a second layer comprising a polyolefin; and (c) a third layer comprising a polyolefin grafted with a monomer; wherein the second layer is disposed between the first layer and the third layer, and further wherein the polyolefin in at least one of the first layer and the third layer is grafted with a monomer and a comonomer containing a benzene ring.
  • Embodiment 2 An embodiment of embodiment 1, wherein the polyolefin of the first layer, second layer, and third layer is independently selected from the group consisting of homo polypropylene, block polypropylene, and random polypropylene.
  • Embodiment 3 An embodiment of any one of the embodiments of embodiments 1-2, wherein the monomer in the first layer and/or the third layer is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, ⁇ -methacrylic acid, methyl methacrylate, and glycidyl methacrylate.
  • Embodiment 4 An embodiment of any one of the embodiments of embodiments 1-3, wherein the polyolefin in the first layer is grafted with the monomer and a comonomer.
  • Embodiment 5 An embodiment of any one of the embodiments of embodiments 1-4, wherein the polyolefin in the third layer is grafted with the monomer and a comonomer.
  • Embodiment 6 An embodiment of any one of the embodiments of embodiments 1-5, wherein the comonomer in the first layer is different than the comonomer in the second layer.
  • Embodiment 7 An embodiment of any one of the embodiments of embodiments 1-5, wherein the comonomer in the first layer is the same as the comonomer in the second layer.
  • Embodiment 8 An embodiment of any one of the embodiments of embodiments 1-7, wherein the comonomer is selected from the group consisting of styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and ⁇ -methylstyrene.
  • Embodiment 9 An embodiment of any one of the embodiments of embodiments 1-8, wherein the monomer is present in the first layer from 1 to 20 wt. %.
  • Embodiment 10 An embodiment of any one of the embodiments of embodiments 1-9, wherein the comonomer is present in the first layer from 1 to 10 wt. %.
  • Embodiment 11 An embodiment of any one of the embodiments of embodiments 1-10, wherein the monomer is present in the third layer from 1 to 20 wt. %.
  • Embodiment 12 An embodiment of any one of the embodiments of embodiments 1-11, wherein the comonomer is present in the third layer from 1 to 10 wt. %.
  • Embodiment 13 An embodiment of any one of the embodiments of embodiments 1-12, wherein the first layer and third layer have substantially the same composition.
  • Embodiment 14 An embodiment of any one of the embodiments of embodiments 1-13, wherein the thickness of the first layer is from 1 to 50 ⁇ m.
  • Embodiment 15 An embodiment of any one of the embodiments of embodiments 1-14, wherein the thickness of the second layer is from 30 to 100 ⁇ m.
  • Embodiment 16 An embodiment of any one of the embodiments of embodiments 1-15, wherein the thickness of the third layer is from 1 to 50 ⁇ m.
  • Embodiment 17 An embodiment of any one of the embodiments of embodiments 1-16,
  • Embodiment 18 An embodiment of any one of the embodiments of embodiments 1-17, wherein the first layer has a melting point from 130 to 160°C.
  • Embodiment 19 An embodiment of any one of the embodiments of embodiments 1-18: wherein the second layer has a melting point from 130 to 190°C.
  • Embodiment 20 An embodiment of any one of the embodiments of embodiments 1-19: wherein the third layer has a melting point from 130 to 160°C.
  • Embodiment 21 An embodiment of any one of the embodiments of embodiments 1-20: wherein the first layer has a melt flow rate of 2 to 20 g/10 min.
  • Embodiment 22 An embodiment of any one of the embodiments of embodiments 1-21: wherein the second layer has a melt flow rate of 2 to 20 g/10 min.
  • Embodiment 23 An embodiment of any one of the embodiments of embodiments 1-22: wherein the third layer has a melt flow rate of 2 to 20 g/10 min.
  • Embodiment 24 An embodiment of any one of the embodiments of embodiments 1-23: wherein the first layer further comprises an additive.
  • a tab sealant was prepared having the following composition:
  • First layer Polypropylene was grafted with maleic anhydride and styrene to form a polymer comprising 1-10 wt. %monomer and 2-5 wt. %comonomer.
  • the polymer was cast and had a thickness of 10-20 microns, a melting point of 135°C and a melt flow rate of 5-6 g/10 minutes.
  • Second layer Polypropylene having a melting point of 165°C and a melt flow rate of 8 g/10 minutes was cast to a thickness from 60 to 80 microns.
  • Third layer Identical to the first layer.
  • a tab sealant was prepared as in Example 1, except that the comonomer was allylbenzene.
  • a tab sealant was prepared as in Example 1, except that no comonomer was included in either the first or third layer.
  • a tab sealant was prepared as in Example 1, except that glycidyl acrylate, which lacks a benzene ring, was used as a comonomer.
  • a tab sealant was prepared as in Example 1, except that the comonomer was present in an amount of less than 1 wt. %.
  • the tab sealant was high frequency welded to the tab lead. Then the welded tab sealant and tab lead were immersed in an electrolyte solution for 72 hours at 85°C to test the peeling of the tab sealant from the tab lead.
  • the corrosion resistance and adhesive strength were rated as follows:
  • a score of 1 represented bad adhesion and the surface of the tab sealant was clear, indicating poor corrosion resistance.
  • a score of 2 represented medium adhesion and the surface of the tab sealant was partially white, indicating that the tab lead and tab sealant had good adhesion strength and that the tab sealant had good corrosion resistance, and partially clear.
  • a score of 3 represented strong adhesion and the surface of the tab sealant was completely white.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Laminated Bodies (AREA)
  • Sealing Battery Cases Or Jackets (AREA)

Abstract

Tab sealants are provided. The tab sealants may comprise three layers. The first and third layer each comprise a base polymer grafted with a monomer. At least one of the first and third layers is grafted with a monomer and a comonomer comprising a benzene ring. The second layer comprises a polyolefin polymer. The tab sealants have improved adhesion, corrosion resistance, and insulation as compared to conventional tab sealants.

Description

TAB SEALANT FIELD OF THE INVENTION
The present invention relates generally to tab sealants. The tab sealants comprise three layers and in particular, at least one of the first and third layer contains a base polymer grafted with a monomer and comonomer comprising a benzene ring.
BACKGROUND OF THE INVENTION
Tab sealants, also referred to as terminal covering resin films, are generally used for covering tabs in battery cells. The tabs have metal leads serving as a metal terminal and the tabs serve as electrode terminals to which electric power is supplied to a cell body. Tab sealants desirably have good adhesion between the tab sealant and the metal lead to prevent peeling off of the tab sealant. Tab sealants also desirably secure insulation of the lead with other parts of the cell body. Finally, tab sealants desirably have good corrosion resistance. Although tab sealants have been described in the art, they have not been able to achieve the desired adhesion and insulation.
US Pat. No. 7,972,722 discloses a lead sealant film and a non-aqueous electrolyte battery. The lead sealant film includes a laminated structure composed of an inner layer, an intermediate layer, and an outer layer. The intermediate layer includes a first acid-modified polypropylene having a high melting-point, and each of the inner layer and the outer layer includes a second acid-modified polypropylene having a low melting-point. A difference between the melting point of the first acid-modified polypropylene and the melting point of the second acid-modified polypropylene is from 20℃ to 25℃.
US Pat. No. 9,123,922 discloses a lithium ion battery exterior material, including a base material layer and a sequentially laminated adhesive layer, aluminum foil layer provided with a corrosion prevention treated layer, and an adhesive resin layer on one surface of the base material layer； wherein, the adhesive resin layer contains an acid-modified polyolefin resin and a miscible elastomer dispersed in the acid-modified polyolefin at a dispersed phase size of 1 nm to less than 1 μm.
US Pub. No. 2010/0221601 discloses an electrical part comprising a lead conductor and a sealed vessel including a metal layer, the lead conductor extending from the inside of the sealed vessel to the outside, wherein the lead conductor and the sealed vessel are fusion-bonded through a thermal adhesive layer at the sealing  portion, and wherein a softening-resistant layer having through holes made in the thickness direction is provided between the lead conductor and the metal layer at the sealing portion. A nonaqueous electrolyte cell comprising an electrode and a nonaqueous electrolyte are both enclosed inside the sealed vessel. Both the sealed vessel and a lead conductor having an insulating coating layer can be used in the electrical part or the like.
US Pub. No. 2015/0311483 discloses a secondary battery metal terminal coating resin film having improved overall performance. It is capable of securing filling ability, adhesive properties, insulating properties of a lead end portion, and shape retention properties of a sealant. Also disclosed is a manufacturing method for the same. Also disclosed is a battery pack using the secondary battery metal terminal coating resin film provided in the lead end portion of a tab used for a laminate-type packaging material for a secondary battery. The secondary battery metal terminal coating resin film is laminated and a coating metal terminal is connected to a positive electrode or a negative electrode of a secondary battery. The melt flow rate of at least one layer of a resin that constitutes the resin film is within a range from about 0.1 g/10 minutes to about 2.5 g/10 minutes.
US Pub. No. 2016/0099446 discloses a resin film, which is adapted for use in a packaging material for secondary cell. The secondary cell has a sealant layer formed of a polyolefin resin. The resin film is disposed between the sealant layer and leads that are connected to a positive electrode and a negative electrode. The layer includes a first layer disposed at a position close to the leads and a second layer disposed at a position close to the sealant layer. A heat quantity of the second layer, measured according to JIS K 7122, is larger than a heat quantity of fusion of the first layer.
US Pub. No. 2016/0099447 discloses a terminal covering resin film for a secondary cell, which is attached so as to cover part of an outer surface of a terminal connected to a power generation element of a secondary cell. The film comprises an innermost layer contacting the terminal and an outermost layer forming a surface opposite to the innermost layer, wherein the innermost layer is a layer of not less than 20 μm in thickness containing an acid-modified polyolefin and a melt flow rate of the innermost layer is not less than 2.0 g/10 minutes.
Other references, including JP 2016091939, JP5730243, disclose tensile storage modulus, dynamic viscoelasticity and melt flow rate values for a resin film.
None of the above-disclosed references, however, provide for tab sealants that have all three desirable traits: good adhesion, insulation, and corrosion resistance.  In view of the foregoing drawbacks, the need exists for a tab sealant with good adhesion, insulation, and corrosion resistance.
SUMMARY OF THE INVENTION
In one embodiment, the invention relates to a tab sealant comprising: (a) a first layer comprising a polyolefin grafted with a monomer； (b) a second layer comprising a polyolefin； and (c) a third layer comprising a polyolefin grafted with a monomer； wherein the second layer is disposed between the first layer and the third layer, and further wherein the polyolefin in at least one of the first layer and the third layer is grafted with a monomer and a comonomer containing a benzene ring. The polyolefin of the first layer, second layer, and third layer may be independently selected from the group consisting of homo polypropylene, block polypropylene, and random polypropylene. The monomer in the first layer and/or the third layer may be selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, α-methacrylic acid, methyl methacrylate, and glycidyl methacrylate. The polyolefin in the first layer may be grafted with the monomer and a comonomer. The polyolefin in the third layer may be grafted with the monomer and a comonomer. The polyolefin in the first layer and the third layer may be grafted with the monomer and a comonomer. In  some aspects, the comonomer in the first layer is different than the comonomer in the second layer. In other aspects, the comonomer in the first layer is the same as the comonomer in the second layer. The comonomer may be selected from the group consisting of styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and α-methylstyrene. The monomer may be present in the first layer from 1 to 20 wt. ％. The comonomer may be present in the first layer from 1 to 10 wt. ％. The monomer may be present in the third layer from 1 to 20 wt. ％. The comonomer may be present in the third layer from 1 to 10 wt. ％. The first layer and third layer may have substantially the same composition. The thickness of the first layer may be from 1 to 50 μm. The thickness of the second layer may be from 30 to 100 μm. The tab sealant of claim 1, wherein the thickness of the third layer is 1 to 50 μm. The first layer may have a melting point from 130 to 160℃. The second layer may have a melting point from 130 to 190℃. The third layer may have a melting point from 130 to 160℃. The first layer may have a melt flow rate of 2 to 20 g/10 min. The second layer may have a melt flow rate of 2 to 20 g/10 min. The third layer may have a melt flow rate of 2 to 20 g/10 min. The first layer may further comprise an additive.
BRIEF DESCRIPTION OF DRAWINGS
The invention is described in detail below with reference to the appended  drawings.
FIG. 1 shows a perspective view of a cell pack in accordance with aspects of the invention；
FIG. 2 shows a perspective view of a tab in accordance with aspects of the invention； and
FIG. 3 shows a cross-sectional view of a tab sealant in accordance with aspects of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to tab sealants that have superior adhesion, insulation, and corrosion resistance as compared to conventional tab sealants. The tab sealant according to the present invention is a three layer film. The first and third layers each (individually) comprise a polyolefin grafted with a monomer. The second layer comprises a polyolefin. In at least one of the first and third layers, the polyolefin is grafted with the monomer and with a comonomer comprising a benzene ring. Surprisingly and unexpectedly, by utilizing the benzene ring comonomer in this manner, the adhesion, insulation and corrosion resistance of the tab sealant is greatly improved as compared to conventional tab sealants, which do not achieve this desired combination of performance characteristics.
In some embodiments of the present invention, the first layer comprises a  polyolefin grafted with a monomer and a comonomer comprising a benzene ring, also referred to as a benzene ring comonomer. In other embodiments, the third layer comprises a polyolefin grafted with a monomer and a benzene ring comonomer. In yet further embodiments, both the first layer and the third layer comprise a polyolefin grafted with a monomer and a benzene ring comonomer, and the composition of the first layer and third layer may be substantially the same.
The overall compositions of the first and third layers may vary widely (as long as the benzene ring comonomer is included in at least one of the layers) . For example, the base polymer may be the same in each layer while the monomer and/or inclusion of a comonomer may differ. Further embodiments may include the same monomer in each layer but with a different base polymer. In yet further embodiments, the base polymer, monomer, and optional comonomer may be the same, but the weight percentages and/or molecular weights of each component may differ between the first and third layer.
As described herein, the tab sealant may be used as a terminal covering. FIG. 1 illustrates a cell pack 10 comprising a cell body 11, packaging material 12,  tabs  13 and 14, lead 15, and tab sealant 16.
FIG. 2 shows tab 13 with a lead 15 serving as a metal terminal, and tab  sealant 16. The lead 15 has a first end portion 15A electrically connected to a power generation element inside of packaging material 12 (shown in FIG. 1) , and a second end portion 15B which is electrically conductive and which has an outer surface that is at least partially exposed to permit connection with an external device to which electric power may be supplied.
FIG. 3 shows a cross-sectional view of tab sealant 16. As shown, tab sealant 16 contains a first layer 17 (an inner layer) , a second layer 18 (an intermediate layer) , and a third layer 19 (an outer layer) . Although the layers are depicted as identical in thickness, as described herein, the thickness of each layer may vary. Additionally, although three layers are shown, additional layers may be included, such as additional inner layers, intermediate layers, and outer layers. Each layer is described more fully below. The tab sealant may be prepared by a co-extrusion casting process, a co-extrusion blowing process, or other processes known in the art. The first, second, and third layer may be co-extruded together in a three-layer co-extrusion machine. The processing temperature may depend on the tab sealant components. Generally, the processing temperature is in the range of 230 to 250℃.
First Layer
The first layer 17, also referred to as an inner layer, is the layer which seals the outer surface of the lead 15 and is therefore in contact with the outer surface of the lead. The first layer may be comprised of a base polymer grafted with a monomer. Preferably, the base polymer may be an olefin polymer. The olefin polymer may include, but is not limited to, polyethylene, including low, medium and high density polyethylenes； polypropylene, including homo, block or random polypropylene； polymethylpentene, polybutene-1； and ethylene-α-olefin copolymers. In some aspects, the olefin polymer is polypropylene.
The base polymer may be grafted with a monomer. The monomer may include, but is not limited to acrylic acid, methacrylic acid, maleic acid, and maleic anhydride, α-methacrylic acid, methyl methacrylate, and glycidyl methacrylate. In some aspects, the monomer is maleic anhydride.
In addition to the base polymer being grafted with a monomer, the base polymer in the first layer may also be grafted with a comonomer, e.g., a monomer containing a benzene ring. For example, the comonomer may be an olefin monomer containing a benzene ring, such as styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and α-methylstyrene.
The inventors have now discovered that by including a comonomer with a benzene ring when grafting the base polymer and monomer, the grafting reaction rate is surprisingly increased, resulting in improved adhesion of the tab sealant. Additionally, the inclusion of a comonomer with a benzene ring when grafting the base polymer and monomer has been found to unexpectedly improve corrosion resistance of the base polymer, e.g., polypropylene.
The base polymer may be present in the first layer in an amount from to 70 to 98 wt. ％, based on the entire weight of the first layer, e.g., from 78.5 to 96.5 wt. ％or from 85 to 95 wt. ％. In terms of lower limits, the first layer comprises at least 70 wt. ％ base polymer, based on the entire weight of the first layer, e.g., at least 78.5 wt. ％or at least 85 wt. ％. In terms of upper limits, the first layer comprises no more than 98 wt. ％ base polymer, based on the entire weight of the first layer, e.g., no more than 96.5 wt. ％ or no more than 95 wt. ％.
The monomer may be present in the first layer in an amount from 1 to 20 wt.％, e.g., from 2 to 15 wt. ％or from 3 to 10 wt. ％, based on the entire weight of the first layer. In terms of lower limits, the first layer comprises at least 1 wt. ％monomer, based on the entire weight of the first layer, e.g., at least 2 wt. ％or at least 3 wt. ％. In terms of  upper limits, the first layer comprises no more than 20 wt. ％monomer, based on the entire weight of the first layer, e.g., no more than 15 wt. ％or no more than 10 wt. ％.
When a comonomer is included, the first layer may comprise from 1 to 10 wt.％comonomer, based on the entire weight of the first layer, e.g., from 1.5 to 7.5 wt. ％ or from 2 to 5 wt. ％. In terms of lower limits, the first layer comprises at least 1 wt. ％ comonomer, based on the entire weight of the first layer, e.g., at least 1.5 wt. ％or at least 2 wt. ％. In terms of upper limits, the first layer comprises no more than 20 wt. ％ monomer, based on the entire weight of the first layer, e.g., no more than 15 wt. ％or no more than 10 wt. ％.
In some aspects, the first layer may comprise an additive. The additive may be present from 1 to 15 wt. ％, based on the entire weight of the first layer, e.g., from 1 to 12 wt. ％or from 1 to 10 wt. ％. Additives known in the art may be included, such as antioxidants.
The first layer may be thinner than those of conventional tab sealants. In one embodiment, the first layer has a thickness ranging from 1 to 50 microns, e.g., from 5 to 25 microns, or from 10 to 20 microns. In terms of lower limits, the first layer may have a thickness of at least 1 micron, e.g., at least 5 microns, or at least 10 microns. It has now been discovered that a thinner first layer may lead to improved corrosion resistance as  compared to a thicker first layer. In some cases, the thickness of the first layer may be selected based on the desired corrosion resistance. Without being bound by theory, it is believed that the existence of the polar groups in the first (and/or third layer) reduce corrosion resistance. Since the second layer may not contain polar groups, its corrosion resistance is better as compared to the first and/or third layer. Therefore, by having a thinner first layer (and/or third layer) , the impact of the first (and/or third layer) on the corrosion resistance of the tab sealant is reduced.
The first layer may have a melting point from 130 to 160℃, e.g., from 130 to 150℃, or from 130 to 140℃. In terms of lower limits, the first layer may have a melting point of at least 130℃, e.g., at least 133℃ or at least 135℃ . In terms of upper limits, the first layer may have a melting point no greater than 160℃, e.g., no greater than 150℃ or 140℃. A melting point below 130℃ may not provide satisfactory heat resistance while a melting point above 160℃ may require too much heat to seal the first layer to the lead, resulting in decreased adhesion and insulation.
The melt flow rate of the first layer may range from 2 to 20 g/10 minutes, e.g., from 3 to 10 g/10 minutes or from 5 to 6 g/10 minutes. In terms of lower limits, the first layer may have a melt flow rate of at least 2 g/10 minutes, e.g., at least 3 g/10 minutes or at least 5 g/10 minutes. In terms of upper limits, the first layer may have a melt flow  rate of no greater than 20 g/10 minutes, e.g., no greater than 10 g/10 minutes or no greater than 6 g/10 minutes. The melt flow rate is an index showing the fluidity of the layer during heating. If the melt flow rate is less than 2 g/10 minutes, sealing of the tab sealant around the lead may be insufficient due to reduced fluidity. If the melt flow rate is greater than 20 g/10 minutes, the first layer may flow too easily, resulting in thinning of the layer during sealing.
Second Layer
As noted above, the second layer 18 may also be referred to as an intermediate layer, and is disposed between the first layer 17 and third layer 19 of the tab sealant. The second layer may be comprised of a polyolefin. The polyolefin film may vary widely. In some embodiments, the polyolefin may include polyethylene, including low, medium and high density polyethylenes； polypropylene, including homo, block or random polypropylene； polymethylpentene, polybutene-1； and ethylene-α-olefin copolymers. In some aspects, the olefin polymer is polypropylene, and may be a casting polypropylene film. In other embodiments, the polyolefin film may comprise any polyolefin material that exhibits good mechanical strength and heat resistance. Exemplary polyolefin films may comprise at least one of a polyimide, a polyester, a polyetherimide (PEI) , a polyethylene naphthalate (PEN) , a polyether sulfone (PES) , a  polysulfone, polymethylpentene (PMP) , a polyvinylidene fluoride (PVDF) , an ethylene-chlorotrifluoroethylene (ECTFE) , or combinations thereof. In some aspects, the polyolefin in the second layer may be the same polyolefin as in the first layer, though the molecular weight and/or melting point may differ.
Exemplary polyolefin films made of polyimide include 
Figure PCTCN2017071918-appb-000001
 available from DuPont, and 
Figure PCTCN2017071918-appb-000002
 available from Kaneka Texas Corporation, Exemplary polyolefin films made of polyester include 
Figure PCTCN2017071918-appb-000003
 avai lable from DuPont, and 2600 polyethylene terephthalate film, available from American Hoechst. Other commercially available polyolefin films include TempaluxTM (PEI) , available from Westlake Plastics Company； Superio-UTTM (PEI) , available from Mitsubishi Plastics, KaladexTM； (PEN) and Teonex (PEN) , both available from DuPont.
The second layer may be thicker than the first layer and/or third layer. For example, the second layer may be at least 10％thicker, e.g., at least 20％thicker, at least 30％thicker, or at least 40％thicker than at least one of the first and third layer. In terms of ranges, the second layer may have a thickness ranging from 30 to 100 microns, e.g., from 45 to 90 microns or from 60 to 80 microns. In terms of lower limits, the second layer may have a thickness of at least 30 microns, e.g., at least 45 microns,  or at least 60 micros. In terms of upper limits, the second layer may have a thickness of no more than 100 microns, e.g., no more than 90 microns or no more than 80 microns.
The second layer may have a melting point from 130 to 190℃, e.g., from 140 to 180℃, or from 150 to 170℃. In terms of lower limits, the second layer may have a melting point of at least 130℃, e.g., at least 140℃ or at least 150℃ . In terms of upper limits, the second layer may have a melting point no greater than 190℃, e.g., no greater than 180℃ or 170℃. As compared to at least one of the first and third layer, the melting point of the second layer may be at least 10℃ greater, e.g., at least 20℃ greater or at least 30℃ greater.
The melt flow rate of the second layer may range from 2 to 20 g/10 minutes, e.g., from 5 to 10 g/10 minutes or from 7 to 9 g/10 minutes. In terms of lower limits, the second layer may have a melt flow rate of at least 2 g/10 minutes, e.g., at least 5 g/10 minutes or at least 7 g/10 minutes. In terms of upper limits, the second layer may have a melt flow rate of no greater than 20 g/10 minutes, e.g., no greater than 10 g/10 minutes or no greater than 9 g/10 minutes.
The tensile strength and flexural modulus of the second layer may be selected based on the desired heat and moisture resistance of the layer, since the second layer provides insulation for the tab sealant. In some aspects, the tensile  strength at yield ranges from 25 to 35 MPa, e.g., from 28 to 34 MPa or from 30 to 32 MPa. The flexural modulus may range from 800 to 1500 MPa, e.g., from 900 to 1450 MPa or from 1100 to 1400 MPa.
Third Layer
The third layer 19, also referred to as an outer layer, is in contact with the second layer 18. The third layer may be the same, substantially the same, or different than the first layer. The third layer may be comprised of a base polymer grafted with a monomer. The base polymer may be an olefin polymer. The olefin polymer may include, but is not limited to, polyethylene, including low, medium and high density polyethylenes； polypropylene, including homo, block or random polypropylene； polymethylpentene, polybutene-1； and ethylene-α-olefin copolymers. In some aspects, the olefin polymer is polypropylene.
The base polymer may be grafted with a monomer. The monomer may include, but is not limited to acrylic acid, methacrylic acid, maleic acid, maleic anhydride, α-methacrylic acid, methyl methacrylate, and glycidyl methacrylate. In some aspects, the monomer is maleic anhydride.
In addition to the base polymer being grafted with a monomer, the base polymer in the third layer may also be grafted with a comonomer, e.g., a monomer  containing a benzene ring. For example, the comonomer may be an olefin monomer containing a benzene ring, such as styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and α-methylstyrene.
As described herein, surprisingly and unexpectedly, it has been discovered that by including a comonomer with a benzene ring when grafting the base polymer and monomer, the grafting reaction rate in increased, resulting in improved adhesion of the tab sealant. This effect is seen when the comonomer is included in the first layer, third layer, or both. Additionally, the inclusion of a comonomer with a benzene ring when grafting the base polymer and monomer results in improved corrosion resistance of the base polymer, e.g., polypropylene.
The base polymer may be present in the third layer in an amount from to 70 to 98 wt. ％, based on the entire weight of the third layer, e.g., from 78.5 to 96.5 wt. ％or from 85 to 95 wt. ％. In terms of lower limits, the third layer comprises at least 70 wt. ％ base polymer, based on the entire weight of the third layer, e.g., at least 78.5 wt. ％or at least 85 wt. ％. In terms of upper limits, the third layer comprises no more than 98 wt. ％ base polymer, based on the entire weight of the third layer, e.g., no more than 96.5 wt.％or no more than 95 wt. ％. The base polymer in the third layer may be the same base polymer as in the first layer, or it may be substantially the same due to differences  in melting point or molecular weight. In some aspects, a different base polymer is used in the third layer as compared to the first layer. In further aspects, the base polymer in the third layer may be the same as the polyolefin in the second layer or it may be substantially the same due to differences in melting point or molecular weight. In still further aspects, a different base polymer is used in the third layer as compared to the polyolefin in the second layer.
The monomer may be present in the third layer in an amount from 1 to 20 wt.％, e.g., from 2 to 15 wt. ％or from 3 to 10 wt. ％, based on the entire weight of the third layer. In terms of lower limits, the third layer comprises at least 1 wt. ％monomer, based on the entire weight of the third layer, e.g., at least 2 wt. ％or at least 3 wt. ％. In terms of upper limits, the third layer comprises no more than 20 wt. ％monomer, based on the entire weight of the third layer, e.g., no more than 15 wt. ％or no more than 10 wt.％. The monomer polymer in the third layer may be the same monomer as in the first layer, or it may be substantially the same due to differences in melting point or molecular weight. In some aspects, a different monomer is used in the third layer as compared to the first layer.
When a comonomer is included, the third layer may comprise from 1 to 10 wt.％comonomer, based on the entire weight of the third layer, e.g., from 1.5 to 7.5  wt.％or from 2 to 5 wt. ％. In terms of lower limits, the third layer comprises at least 1 wt.％comonomer, based on the entire weight of the third layer, e.g., at least 1.5 wt. ％or at least 2 wt. ％. In terms of upper limits, the third layer comprises no more than 20 wt. ％ monomer, based on the entire weight of the third layer, e.g., no more than 15 wt. ％or no more than 10 wt. ％. When both the first layer and the third layer include a comonomer, the comonomer in the third layer may be the same comonomer as in the first layer, or it may be substantially the same due to differences in melting point or molecular weight. In some aspects, a different comonomer is used in the third layer as compared to the first layer.
In some aspects, the third layer may comprise an additive. The additive may be present from 1 to 15 wt. ％, based on the entire weight of the third layer, e.g., from 1 to 12 wt. ％or from 1 to 10 wt. ％. Additives known in the art may be included, such as antioxidants.
The third layer may have a thickness ranging from 1 to 50 microns, e.g., from 5 to 25 microns, or from 10 to 20 microns. In terms of lower limits, the third layer may have a thickness of at least 1 micron, e.g., at least 5 microns, or at least 10 micros. The thickness of the third layer may be selected based on the desired corrosion resistance. Without being bound by theory, it is believed that a thinner first layer leads to improved  corrosion resistance as compared to a thicker first layer. The thickness of the third layer may be the as the first layer, or it may be different. In some aspects, the thickness of the third layer is within ± 30％of the thickness of the first layer, e.g., within ± 20％or ± 10％. The total thickness of the first and third layer combined may range from 2 to 100 microns, e.g., from 10 to 80 microns, or from 20 to 40 microns. The total thickness of the first layer, second layer, and third layer, combined, may range from 32 to 200 microns, e.g., from 55 to 190 microns, or from 80 to 120 microns.
The third layer may have a melting point from 130 to 160℃, e.g., from 130 to 150℃, or from 130 to 140℃. In terms of lower limits, the third layer may have a melting point of at least 130℃, e.g., at least 133℃ or at least 135℃. In terms of upper limits, the first layer may have a melting point no greater than 160℃, e.g., no greater than
150℃ or 140℃. In some aspects, the melting point of the third layer is within 10℃ of the melting point of the first layer, e.g., within 5℃ or within 3℃. In further aspects, the melting point of the third layer is within 40℃ of the melting point of the first layer, e.g., within 35℃ or within 30℃.
The melt flow rate of the third layer may range from 2 to 20 g/10 minutes, e.g., from 3 to 10 g/10 minutes or from 5 to 6 g/10 minutes. In terms of lower limits, the third layer may have a melt flow rate of at least 2 g/10 minutes, e.g., at least 3 g/10  minutes or at least 5 g/10 minutes. In terms of upper limits, the third layer may have a melt flow rate of no greater than 20 g/10 minutes, e.g., no greater than 10 g/10 minutes or no greater than 6 g/10 minutes. In some aspects, the melt flow rate of the third layer is within 3 g/10 minutes of the melt flow rate of the first layer, e.g., within 2 g/10 minutes or within 1 g/10 minutes. In some aspects, the melt flow rate of the third layer may be within 5 g/10 minutes of the melt flow rate of the second layer, e.g., within 4 g/10 minutes or within 3 g/10 minutes.
The following embodiments are contemplated. All combinations of features and embodiments are contemplated.
Embodiment 1: A tab sealant comprising: (a) a first layer comprising a polyolefin grafted with a monomer； (b) a second layer comprising a polyolefin； and (c) a third layer comprising a polyolefin grafted with a monomer； wherein the second layer is disposed between the first layer and the third layer, and further wherein the polyolefin in at least one of the first layer and the third layer is grafted with a monomer and a comonomer containing a benzene ring.
Embodiment 2: An embodiment of embodiment 1, wherein the polyolefin of the first layer, second layer, and third layer is independently selected from the group consisting of homo polypropylene, block polypropylene, and random polypropylene. 
Embodiment 3: An embodiment of any one of the embodiments of embodiments 1-2, wherein the monomer in the first layer and/or the third layer is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, α-methacrylic acid, methyl methacrylate, and glycidyl methacrylate.
Embodiment 4: An embodiment of any one of the embodiments of embodiments 1-3, wherein the polyolefin in the first layer is grafted with the monomer and a comonomer.
Embodiment 5: An embodiment of any one of the embodiments of embodiments 1-4, wherein the polyolefin in the third layer is grafted with the monomer and a comonomer.
Embodiment 6: An embodiment of any one of the embodiments of embodiments 1-5, wherein the comonomer in the first layer is different than the comonomer in the second layer.
Embodiment 7: An embodiment of any one of the embodiments of embodiments 1-5, wherein the comonomer in the first layer is the same as the comonomer in the second layer.
Embodiment 8: An embodiment of any one of the embodiments of embodiments 1-7, wherein the comonomer is selected from the group consisting of  styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and α-methylstyrene.
Embodiment 9: An embodiment of any one of the embodiments of embodiments 1-8, wherein the monomer is present in the first layer from 1 to 20 wt. ％.
Embodiment 10: An embodiment of any one of the embodiments of embodiments 1-9, wherein the comonomer is present in the first layer from 1 to 10 wt. ％.
Embodiment 11: An embodiment of any one of the embodiments of embodiments 1-10, wherein the monomer is present in the third layer from 1 to 20 wt. ％.
Embodiment 12: An embodiment of any one of the embodiments of embodiments 1-11, wherein the comonomer is present in the third layer from 1 to 10 wt. ％.
Embodiment 13: An embodiment of any one of the embodiments of embodiments 1-12, wherein the first layer and third layer have substantially the same composition.
Embodiment 14: An embodiment of any one of the embodiments of embodiments 1-13, wherein the thickness of the first layer is from 1 to 50 μm.
Embodiment 15: An embodiment of any one of the embodiments of  embodiments 1-14, wherein the thickness of the second layer is from 30 to 100 μm.
Embodiment 16: An embodiment of any one of the embodiments of embodiments 1-15, wherein the thickness of the third layer is from 1 to 50 μm.
Embodiment 17: An embodiment of any one of the embodiments of embodiments 1-16,
Embodiment 18: An embodiment of any one of the embodiments of embodiments 1-17, wherein the first layer has a melting point from 130 to 160℃.
Embodiment 19: An embodiment of any one of the embodiments of embodiments 1-18: wherein the second layer has a melting point from 130 to 190℃.
Embodiment 20: An embodiment of any one of the embodiments of embodiments 1-19: wherein the third layer has a melting point from 130 to 160℃.
Embodiment 21: An embodiment of any one of the embodiments of embodiments 1-20: wherein the first layer has a melt flow rate of 2 to 20 g/10 min.
Embodiment 22: An embodiment of any one of the embodiments of embodiments 1-21: wherein the second layer has a melt flow rate of 2 to 20 g/10 min.
Embodiment 23: An embodiment of any one of the embodiments of embodiments 1-22: wherein the third layer has a melt flow rate of 2 to 20 g/10 min.
Embodiment 24: An embodiment of any one of the embodiments of embodiments 1-23: wherein the first layer further comprises an additive.
The present invention will be better understood in view of the following non-limiting examples.
Examples
Example 1
A tab sealant was prepared having the following composition:
First layer: Polypropylene was grafted with maleic anhydride and styrene to form a polymer comprising 1-10 wt. ％monomer and 2-5 wt. ％comonomer. The polymer was cast and had a thickness of 10-20 microns, a melting point of 135℃ and a melt flow rate of 5-6 g/10 minutes.
Second layer: Polypropylene having a melting point of 165℃ and a melt flow rate of 8 g/10 minutes was cast to a thickness from 60 to 80 microns.
Third layer: Identical to the first layer.
Example 2
A tab sealant was prepared as in Example 1, except that the comonomer was allylbenzene.
Comparative Example 1
A tab sealant was prepared as in Example 1, except that no comonomer was included in either the first or third layer.
Comparative Example 2
A tab sealant was prepared as in Example 1, except that glycidyl acrylate, which lacks a benzene ring, was used as a comonomer.
Comparative Example 3
A tab sealant was prepared as in Example 1, except that the comonomer was present in an amount of less than 1 wt. ％.
Testing
In order to compare the effect of including a comonomer on corrosion resistance and adhesive strength, the tab sealant was high frequency welded to the tab lead. Then the welded tab sealant and tab lead were immersed in an electrolyte solution for 72 hours at 85℃ to test the peeling of the tab sealant from the tab lead. The corrosion resistance and adhesive strength were rated as follows:
A score of 1 represented bad adhesion and the surface of the tab sealant was clear, indicating poor corrosion resistance. A score of 2 represented medium adhesion and the surface of the tab sealant was partially white, indicating that the tab lead and  tab sealant had good adhesion strength and that the tab sealant had good corrosion resistance, and partially clear. A score of 3 represented strong adhesion and the surface of the tab sealant was completely white.
The results of the testing of tab sealant of Examples 1-2 and Comparative Examples 1-3 are shown below in Table 1.
Figure PCTCN2017071918-appb-000004
While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. It should be understood that aspects of the invention and portions of various embodiments and various features recited herein and/or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be  appropriately combined with other embodiments as will be appreciated by one of ordinary skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

Claims (24)

  1. A tab sealant comprising:
    (a) a first layer comprising a polyolefin grafted with a monomer；
    (b) a second layer comprising a polyolefin； and
    (c) a third layer comprising a polyolefin grafted with a monomer；
    wherein the second layer is disposed between the first layer and the third layer, and further wherein the polyolefin in at least one of the first layer and the third layer is grafted with a monomer and a comonomer containing a benzene ring.
  2. The tab sealant of claim 1, wherein the polyolefin of the first layer, second layer, and third layer is independently selected from the group consisting of homo polypropylene, block polypropylene, and random polypropylene.
  3. The tab sealant of any of the preceding claims, wherein the monomer in the first layer and/or the third layer is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, α-methacrylic acid, methyl methacrylate, and glycidyl methacrylate.
  4. The tab sealant of any of the preceding claims, wherein the polyolefin in the first layer is grafted with the monomer and a comonomer.
  5. The tab sealant of any of the preceding claims, wherein the polyolefin in the third layer is grafted with the monomer and a comonomer.
  6. The tab sealant of any of the preceding claims, wherein the polyolefin in the first layer and the third layer is grafted with the monomer and a comonomer.
  7. The tab sealant of claim 6, wherein the comonomer in the first layer is different than the comonomer in the third layer.
  8. The tab sealant of claim 6, wherein the comonomer in the first layer is the same as the comonomer in the third layer.
  9. The tab sealant of any of the preceding claims, wherein the comonomer is selected from the group consisting of styrene, dipropyl phthalate, diallyl phthalate, allylbenzene, methyleugenol, and α-methylstyrene.
  10. The tab sealant of any of the preceding claims, wherein the monomer is present in the first layer from 1 to 20 wt. ％.
  11. The tab sealant of any of the preceding claims, wherein the comonomer is present in the first layer from 1 to 10 wt. ％.
  12. The tab sealant of any of the preceding claims, wherein the monomer is present in the third layer from 1 to 20 wt. ％.
  13. The tab sealant of any of the preceding claims, wherein the comonomer is present in the third layer from 1 to 10 wt. ％.
  14. The tab sealant of any of the preceding claims, wherein the first layer and third layer have substantially the same composition.
  15. The tab sealant of any of the preceding claims, wherein the thickness of the first layer is from 1 to 50 μm.
  16. The tab sealant of any of the preceding claims, wherein the thickness of the second layer is from 30 to 100 μm.
  17. The tab sealant of any of the preceding claims, wherein the thickness of the third layer is from 1 to 50 μm.
  18. The tab sealant of any of the preceding claims, wherein the first layer has a melting point from 130 to 160℃.
  19. The tab sealant of any of the preceding claims, wherein the second layer has a melting point from 130 to 190℃.
  20. The tab sealant of any of the preceding claims, wherein the third layer has a melting point from 130 to 160℃.
  21. The tab sealant of any of the preceding claims, wherein the first layer has a melt flow rate of 2 to 20 g/10 min.
  22. The tab sealant of any of the preceding claims, wherein the second layer has a melt flow rate of 2 to 20 g/10 min.
  23. The tab sealant of any of the preceding claims, wherein the third layer has a melt flow rate of 2 to 20 g/10 min.
  24. The tab sealant of any of the preceding claims, wherein the first layer further comprises an additive.
PCT/CN2017/071918 2017-01-20 2017-01-20 Tab sealant WO2018133030A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
PCT/CN2017/071918 WO2018133030A1 (en) 2017-01-20 2017-01-20 Tab sealant
TW106146596A TWI655280B (en) 2017-01-20 2017-12-29 Joint seal
CN201810048542.4A CN108274869A (en) 2017-01-20 2018-01-18 Joint sealing body

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2017/071918 WO2018133030A1 (en) 2017-01-20 2017-01-20 Tab sealant

Publications (1)

Publication Number Publication Date
WO2018133030A1 true WO2018133030A1 (en) 2018-07-26

Family

ID=62804065

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2017/071918 WO2018133030A1 (en) 2017-01-20 2017-01-20 Tab sealant

Country Status (3)

Country Link
CN (1) CN108274869A (en)
TW (1) TWI655280B (en)
WO (1) WO2018133030A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021006351A1 (en) * 2019-07-10 2021-01-14 大日本印刷株式会社 Adhesive film for metal terminals, metal terminal with adhesive film for metal terminals, electricity storage device using said adhesive film for metal terminals, and method for producing electricity storage device
WO2021246472A1 (en) * 2020-06-03 2021-12-09 藤森工業株式会社 Sealing film, electrode lead wire member, and battery

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN86108901A (en) * 1985-11-29 1987-12-23 美国制罐公司 The packing that multilayered packaging film and current film form
JP2002361798A (en) * 2001-06-07 2002-12-18 Toppan Printing Co Ltd Laminated body
US20110159297A1 (en) * 2009-12-30 2011-06-30 Equistar Chemicals, Lp Multilayer structures with common tie layer
CN103155207A (en) * 2010-10-14 2013-06-12 凸版印刷株式会社 Exterior material for lithium ion battery
KR101366217B1 (en) * 2013-02-26 2014-02-24 한화폴리드리머 주식회사 Packaging material for polymer cell and process for producing the same

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100619654B1 (en) * 1998-10-30 2006-09-05 소니 가부시끼 가이샤 Non-aqueous Electrolytic Cell and Production Method Therefor
JP3615103B2 (en) * 1999-11-18 2005-01-26 日本製紙株式会社 Modified polyolefin composition and use thereof
JP4508199B2 (en) * 2007-02-05 2010-07-21 ソニー株式会社 Lead sealant film and non-aqueous electrolyte battery
CN103026528A (en) * 2010-08-11 2013-04-03 大仓工业株式会社 Method for producing tape for terminal adhesion and tape for terminal adhesion
WO2012063764A1 (en) * 2010-11-11 2012-05-18 藤森工業株式会社 Process for producing sealing film, and sealing film
KR101877594B1 (en) * 2011-05-11 2018-07-12 도판 인사츠 가부시키가이샤 Cladding for lithium ion cell, lithium ion cell, and method for producing lithium ion cell

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN86108901A (en) * 1985-11-29 1987-12-23 美国制罐公司 The packing that multilayered packaging film and current film form
JP2002361798A (en) * 2001-06-07 2002-12-18 Toppan Printing Co Ltd Laminated body
US20110159297A1 (en) * 2009-12-30 2011-06-30 Equistar Chemicals, Lp Multilayer structures with common tie layer
CN103155207A (en) * 2010-10-14 2013-06-12 凸版印刷株式会社 Exterior material for lithium ion battery
KR101366217B1 (en) * 2013-02-26 2014-02-24 한화폴리드리머 주식회사 Packaging material for polymer cell and process for producing the same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021006351A1 (en) * 2019-07-10 2021-01-14 大日本印刷株式会社 Adhesive film for metal terminals, metal terminal with adhesive film for metal terminals, electricity storage device using said adhesive film for metal terminals, and method for producing electricity storage device
JPWO2021006351A1 (en) * 2019-07-10 2021-12-02 大日本印刷株式会社 An adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals, a power storage device using the adhesive film for metal terminals, and a method for manufacturing the power storage device.
CN114097130A (en) * 2019-07-10 2022-02-25 大日本印刷株式会社 Adhesive film for metal terminal, metal terminal with adhesive film for metal terminal, electric storage device using adhesive film for metal terminal, and method for manufacturing electric storage device
EP3998650A4 (en) * 2019-07-10 2023-07-19 Dai Nippon Printing Co., Ltd. Adhesive film for metal terminals, metal terminal with adhesive film for metal terminals, electricity storage device using said adhesive film for metal terminals, and method for producing electricity storage device
WO2021246472A1 (en) * 2020-06-03 2021-12-09 藤森工業株式会社 Sealing film, electrode lead wire member, and battery

Also Published As

Publication number Publication date
TWI655280B (en) 2019-04-01
CN108274869A (en) 2018-07-13
TW201835281A (en) 2018-10-01

Similar Documents

Publication Publication Date Title
JP6157569B2 (en) Secondary battery and thermal adhesive insulating film for secondary battery
JP6381234B2 (en) Insulating film for sealing tab and electrochemical device
US10096811B2 (en) Separator for a non-aqueous secondary battery and non-aqueous secondary battery
JP5129895B2 (en) Nonaqueous secondary battery separator and nonaqueous secondary battery
JP7416979B2 (en) Pouch film laminates, pouch-type battery cases, and pouch-type secondary batteries
US20170222280A1 (en) Laminated battery
JP6497320B2 (en) Manufacturing method of terminal covering resin film for secondary battery
KR20180077190A (en) Separator for non-aqueous secondary battery and non-aqueous secondary battery
JP6325180B1 (en) Non-aqueous secondary battery separator and non-aqueous secondary battery
KR20190015105A (en) Separator for non-aqueous secondary battery, and non-aqueous secondary battery
JP7066719B2 (en) Electrode sheet manufacturing method, all-solid-state battery and all-solid-state battery manufacturing method
TWI623126B (en) Resin film, metal terminal member, and secondary battery
WO2018092640A1 (en) High power battery and battery case
JP5005935B2 (en) Nonaqueous electrolyte secondary battery
CN105340118A (en) Jelly-roll type electrode assembly and secondary battery having same
JP6974930B2 (en) Non-aqueous electrolyte secondary battery
WO2018133030A1 (en) Tab sealant
KR20180101182A (en) Separator for non-aqueous secondary battery, and non-aqueous secondary battery
JP2018137140A (en) Nonaqueous secondary battery separator and nonaqueous secondary battery
US9985269B2 (en) Highly heat-resistant film for electrode terminals
JP2015201387A (en) Sheath material for secondary battery, secondary battery, and manufacturing method of the same
JP4954468B2 (en) Winding electrode, manufacturing method thereof, and battery manufacturing method
JP6354167B2 (en) Power storage device exterior materials
JP2021517710A (en) Pouch for secondary battery and pouch type secondary battery
JP2002075297A (en) Battery

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17893474

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17893474

Country of ref document: EP

Kind code of ref document: A1