AU747013B2

AU747013B2 - Hydroxy-functional polyether laminates

Info

Publication number: AU747013B2
Application number: AU39096/99A
Authority: AU
Inventors: Terry H. Fiero; Robert H. Kelch; Bradley Day Stevens
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1997-12-19
Filing date: 1998-10-23
Publication date: 2002-05-09
Anticipated expiration: 2018-10-23
Also published as: NZ504927A; CA2314243A1; WO1999032281A1; AU3909699A; JP2001526130A; CN1282292A; KR20010033280A; ID22593A; EP1040000A1; ZA9811646B; BR9813782A

Description

I~iLLPh~T~TII UYI TII- 43397 HYDROXY-FUNCTIONAL POLYETHER LAM INATES This invention relates to metal-polymer laminates useful for fabricating articles, such as beverage containers and aerosol containers.

Metal-polymer laminates are known and are described, for example, in U.S. Patents 4.626,157; 4,423,823; 4,034,132; 4,686,152; 4,734,303 and 4,361,020. The polymers employed in preparing the laminates include polyesters, polypropylene, polyethylene, polycarbonate, polyimide and blends thereof. Films prepared from these polymers suffer from their inadequate adhesion to the metal, their inability to elongate during metal forming due to the highly oriented nature of the polymer film, and their tendency to delaminate during forming and/or end-use application. Thin polyolefin-based films with polar comonomer adhesive layers, while offering good adhesion characteristics to metal, and good elongation during metal laminate forming, can suffer from inadequate laminate cuttability (resulting in coating "stringing"), and inadequate scratch resistance and end-use toughness.

It would be desirable to provide polymer films with such characteristics as adequate toughness, abrasion resistance, thermal stability, ductility, formability, good barrier properties and chemical resistance to many chemicals.

In a first aspect, the present invention is a laminate structure comprising one or more layers of a metal and one or more layers of a hydroxy-functional polyether and, optionally, one or more layers of an organic polymer which is not hydroxy-functional polyether.

In a second aspect, the present invention is a container comprising a laminate structure having one or more layers of a metal and one or more layers of a hydroxy-functional polyether and, optionally, one or more layers of an organic polymer which is not hydroxy-functional polyether.

Preferably, the hydroxy-functional polyetherhydroxy-functional polyethers employed in the practice of the present invention for preparing the polymer layer(s) are: hydroxy-functional polyethers having repeating units represented by the formula:

SOH

I 0 OCH20CH20Ar

I

S R 'n- '44 T^ A)1- AMENDED

SHEET

WO 99/32281 WO 9932281PCTIUS98/22430 amide- and hydroxymethyl-functional polyethers having repeating units represented by the formula: OH OH

OCH

2 6Y 2 OArl

OCH

2

L~H

2 OAr 2 R R )x 1-x L -J n hydroxy-functional poly(ether sulfonamides) having repeating units represented by the formula: OH R 2 0 P OH I 1 1I 1 11 1 1 IOCH 2 CCH2 N-S-R- S-NCH 2 CCH:k 2 Ar l l R 0 0P n or

OH

OCH

2

CCH

2

-N-H-

2

CH

2 OAr IIIb 2 n poly(hydroxy amide ethers) having repeating units represented independently by any one of the following formulas: OH 0 0 1 1 1 11 OC~h 2 CCi 2 A-NHC-R-CNHAr Iva n OH 0 0 1 11 1 11 UCk1 2

CH

2 .K -CN- -NHCAr IVb

R

n or WO 99/32281 WO 9932281PCT/US98/22430 OH 0 UL:1' 2

UUCH

2 uArCNHAr IVc poly(hydroxy ester ethers) having repeating units represented by the formula: OH 0 0 OH 0 0 CH 2 0H 1 11 1 11 1 0 11 1 1 1

OCH

2

CCH

2 C-R -CO CH 2

CCH

2 OR OC-R -COC-CE RXY Y R R x poly(hydroxy amide ethers) having repeating units represented by any one of the following formulas: VIa VIb

VIC

poly(hydroxyamino ethers) having repeating units represented by the formula: OH OH

OCH-

2 CCH1 2 A-CHi- 2

CCH

2 OAr R n

VII

WO 99/32281 PCT/US98/22430 and hydroxy-functional polyethers having repeating units represented by the formula: OH OH

OCH

2 CCH2- X- CH 2

CCH

2 0-Ar VIII R R n wherein each Ar individually represents a divalent aromatic moiety, substituted divalent aromatic moiety or heteroaromatic moiety, or a combination of different divalent aromatic moieties, substituted aromatic moieties or heteroaromatic moieties; R is individually hydrogen or a monovalent hydrocarbyl moiety; each Ar' is a divalent aromatic moiety or combination of divalent aromatic moieties bearing amide or hydroxymethyl groups; each Ar 2 is the same or different than Ar and is individually a divalent aromatic moiety, substituted aromatic moiety or heteroaromatic moiety or a combination of different divalent aromatic moieties, substituted aromatic moieties or heteroaromatic moieties; R' is individually a predominantly hydrocarbylene moiety, such as a divalent aromatic moiety, substituted divalent aromatic moiety, divalent heteroaromatic moiety, divalent alkylene moiety, divalent substituted alkylene moiety or divalent heteroalkylene moiety or a combination of such moieties; R 2 is individually a monovalent hydrocarbyl moiety; A is an amine moiety or a combination of different amine moieties; X is an amine, an arylenedioxy, an arylenedisulfonamido or an arylenedicarboxy moiety or combination of such moieties; and Ar 3 is a "cardo" moiety represented by any one of the following formulas:

R

2

R

2 R R ,0A, WO 99/32281 PCT/US98/22430 SII or or

R

2

R

2

Y

N R 3 0 wherein Y is nil, a covalent bond, or a linking group, wherein suitable linking groups include, for example, an oxygen atom, a sulfur atom, a carbonyl atom, a sulfonyl group, or a methylene group or similar linkage; n is an integer from 10 to 1000; x is 0.01 to 1.0; and y is 0 to The term "predominantly hydrocarbylene" means a divalent radical that is predominantly hydrocarbon, but which optionally contains a minor amount of heteroatomic moiety such as oxygen, sulfur, imino, sulfonyl, or sulfoxyl.

The hydroxy-functional polyethers represented by Formula I can be prepared, for example, by allowing a diglycidyl ether or combination of diglycidyl ethers to react with a dihydric phenol or a combination of dihydric phenols using the process described in U.S. Patent 5,164,472. Alternatively, the hydroxy-functional polyethers are obtained by allowing a dihydric phenol or combination of dihydric phenols to react with an epihalohydrin by the process described by Reinking, Barnabeo and Hale in the Journal of Applied Polymer Science, Volume 7, page 2135 (1963).

The amide- and hydroxymethyl-functional polyethers represented by Formula II can be prepared, for example, by reacting the diglycidyl ethers, such as the diglycidyl ether of bisphenol A, with a dihydric phenol having pendant amido, N-substituted amido and/or hydroxyalkyl moieties, such as 2,2-bis(4-hydroxyphenyl)acetamide and WO 99/32281 PCT/US98/22430 These polyethers and their preparation are described in U.S. Patents 5,115,075 and 5,218,075.

The hydroxy-functional poly(ether sulfonamides) represented by Formula III are prepared, for example, by polymerizing an N,N'-dialkyl or N,N'-diaryldisulfonamide with a diglycidyl ether as described in U.S. Patent 5,149,768.

The poly(hydroxy amide ethers) represented by Formula IV are prepared by contacting a bis(hydroxyphenylamido)alkane or arene, or a combination of 2 or more of these compounds, such as N,N'-bis(3-hydroxyphenyl) adipamide or N,N'-bis(3-hydroxyphenyl)glutaramide, with an epihalohydrin as described in U.S. Patent 5,134,218.

The poly(hydroxy ester ethers) represented by Formula V are prepared by reacting diglycidyl ethers of aliphatic or aromatic diacids, such as diglycidyl terephthalate, or diglycidyl ethers of dihydric phenols with, aliphatic or aromatic diacids such as adipic acid or isophthalic acid. These polyesters are described in U.S. Patent 5,171,820.

The poly(hydroxy amide ethers) represented by Formula VI are preferably prepared by contacting an N,N'-bis(hydroxyphenylamido)alkane or arene with a diglycidyl ether as described in U.S. Patents 5,089,588 and 5,143,998.

The polyetheramines represented by Formula VII are prepared by contacting one or more of the diglycidyl ethers of a dihydric phenol with an amine having two amine hydrogens under conditions sufficient to cause the amine moieties to react with epoxy moieties to form a polymer backbone having amine linkages, ether linkages and pendant hydroxyl moieties. These polyetheramines are described in U.S. Patent5,275,853.

The hydroxy-functional polyethers represented by Formula VIII are prepared, for example, by contacting at least one dinucleophilic monomer with at least one diglycidyl ether of a cardo bisphenol, such as 9,9-bis(4-hydroxyphenyl)fluorene, phenolphthalein, or phenolphthalimidine or a substituted cardo bisphenol, such as a substituted bis(hydroxyphenyl)fluorene, a substituted phenolphthalein or a substituted phenolphthalimidine under conditions sufficient to cause the nucleophilic moieties of the dinucleophilic monomer to react with epoxy moieties to form a polymer backbone containing pendant hydroxy moieties and ether, imino, amino, sulfonamido or ester linkages. These hydroxy-functional polyethers are described in U.S. Application Serial No. 131,110, filed October 1,1993.

WO 99/32281 PCT/US98/22430 The hydroxy-functional polyethers commercially available from Phenoxy Associates, Inc. are suitable for use in the present invention. These hydroxyfunctional polyethers are the condensation reaction products of a dihydric polynuclear phenol, such as bisphenol A, and an epihalohydrin and have the repeating units represented by Formula I wherein Ar is an isopropylidene diphenylene moiety. The process for preparing them are described in U.S. Patent 3,305,528.

Most preferably, the hydroxy-functional polyethers employed in the practice of the present invention are the polyetheramines represented by Formula VII.

Preferably, the hydroxy-functional polyethers exhibit a molecular weight of at least 20,000 but less than 100,000, and preferably at least 30,000 and less than 80,000.

Hydroxy-functional polyethers having low molecular weight or exceedingly high molecular weight are difficult to process and exhibit insufficient physical properties to form into flexible films or adequately wet-out and adhere to a metal substrate.

To improve the chemical resistance, hardness, thermal resistance or other performance characteristics of the hydroxy-functional polyethers, the polyethers can be modified by known copolymerization or graft copolymerization techniques or by cross-linking with ethylenically unsaturated dicarboxylic acid anhydride or anhydride precursor such as succinic or maleic anhydride; diisocyanates, or formaldehydes, such as phenol-, urea- or melamine formaldehyde. Such reactions (copolymerization, cross-linking) can be performed by a reactive extrusion process wherein the reactants are fed into and reacted in an extruder using the conditions described in U.S. Patent 4,612,156. Such reactions can also take place after the films or laminates are formed by thermal, moisture or UV-induced reactions.

Monolayer and multilayer films can be prepared from the hydroxy-functional polyethers by using conventional extrusion techniques such as feedblock extrusion, multimanifold or die coextrusion or combinations of the two, or by slot-die casting or annular blown film extrusion; extrusion coating onto another substrate layer; or by solvent spraying or solution casting. Solution casting is a well known process and is described, for example, in the Plastics Engineering Handbook of the Society of the Plastics Industry, Inc, 4th Edition, page 448. Additionally, multiple plies of hydroxy-functional polyethers and/or other organic polymers can be adhered together via a conventional process such as hot-roll thermal lamination in order to produce a multi-ply structure. This lamination of multiple separate layers or plies is especially beneficial when significant melt viscosity differences between the 43397 various layers prevent uniform coextrusion of the layers. The films can be subsequently oriented monoaxially, in the machine or transverse direction, or blaxially, in both machine and transverse directions, to further improve their physical properties, such as increased tensile strength and secant modulus and reduced elongation. These property changes can be beneficial when stamping or cutting a polymer-metal laminate. In general, multilayer films can be formed from the hydroxy-functional polyethers of the present invention by coextruding one or more layers of the hydroxy-functional polyethers and one or more layers of an organic polymer which is not a hydroxy-functional polyether.

Such multilayered structures, whether formed via coextrusion, extrusion coating, liquid coating or multi-ply lamination, can be beneficially used to achieve composite properties not attainable by monolayer film or multicomponent blends. One such example involves the use of coextrusion to add an organic adhesive layer to an otherwise poorly adhering hydroxy-functional polyether to bond the phenoxyether polymer to a metal substrate. In preparing the monolayer and multilayer films, thermoplastic polyurethanes

(TPU),

thermoplastic elastomer (TPE), polyester (PET), glycol-modified copolyester (PETG), polyolefins or other thermoplastic resins can be blended with the hydroxy-functional polyether at levels of less than 50 weight percent and, preferably less than 30 weight percent, based on the weight of the hydroxy-functional polyether layer. These other polymers can be blended into the hydroxy-functional polyether in order to reduce composition cost, to modify physical properties, barrier or permeability properties, or adhesion characteristics.

Additives such as fillers, pigments, stabilizers, impact modifiers, plasticizers, carbon black, conductive metal particles, abrasives and lubricating polymers may be incorporated into the hydroxy-functional polyether films. The method of incorporating the additives is not critical. The additives can conveniently be added to the hydroxy-functional polyether prior to preparing the films. If the polymer is prepared in solid form, the additives can be added to the melt prior to preparing the films.

Preferably, the hydroxy-functional polyether films exhibit an ultimate tensile strength of at least 48.3 M N/m 2 (7,000 psi), a yield elongation of 4 to 10 percent, an ultimate elongation of 50 to 400 percent arid a 2 percent secant modulus of at least 1379.0 M N/m 2 (200,000 psi.) The relatively high tensile strength, high modulus and low elongation of the film allows the film laminate to be cut and stamped in a high speed die cutting operation without undesirable film elongation and stringing over the edge of the cut metal laminate in an operation used to produce aerosol valve mounting cups. As used herein, the term "stringing" refers to a partially attached polymeric coating fiber or "hair" caused by the incomplete cutting of the metal -8- 'AMENDE SIEfE WO 99/32281 PCT/US98/22430 laminate coating. The tough, elongatable polymeric coating is stretched over the cut edge of the metal where it is partially cut off, leaving either a ragged edge of polymer or a thin partially detached polymer strip, hair, string or fiber. It is also desirable that the hydroxyfunctional polyether film exhibits a minimum of 2.0 lb/inch adhesion to a metal substrate, preferably a minimum of at least 3.0 Ib/inch.

The monolayer film comprises the hydroxy-functional polyether.

Organic polymers which are not hydroxy-functional polyethers can be adhered to one or both sides of the hydroxy-functional polyether film layer to produce a multilayer film. Thus, the multilayer film can be in the form of the following structures: a two-layer film comprising a first layer of the hydroxy-functional polyether and a second layer comprising an organic polymer which is not a hydroxy-functional polyether.

a three-layer film comprising a first outer layer of an organic polymer, a core layer of the hydroxy-functional polyether and a second outer layer of an organic polymer which is the same as or different from the organic polymer of the first outer layer; a three-layer film comprising a first outer layer of the hydroxy-functional polyether, a core layer of an organic polymer which is not a hydroxy-functional polyether and a second outer layer of an organic polymer which is the same as or different from the organic polymer of the core layer; or a three-layer film comprising a first outer layer of the hydroxy-functional polyether, a core layer of an organic polymer which is not a hydroxy-functional polyether and a second outer layer of a hydroxy-functional polyether which is the same as or different from the hydroxy-functional polyether of the first outer layer.

Organic polymers which are not hydroxy-functional polyethers which can be employed in the practice of the present invention for preparing the multilayer film include crystalline thermoplastic polyesters, such as polyethylene terephthalate (PET), amorphous thermoplastic polyesters such as glycol modified polyester (PETG); polyamides, polyolefins, and [polyolefins] styrenics based on monovinyl aromatic monomers; carboxylic acid modified olefin copolymers, such as ethylene-acrylic acid and ethylene-methacrylic acid copolymers, and anhydride-modified polymers, such as polyethylene grafted with maleic anhydride, ethylene-vinyl acetate-grafted with maleic anhydride and ethylene-butylacrylate-maleic anhydride terpolymer.

l..T lL.| 1 i ,I U 43397 Polyesters and methods for their preparation are well known in the art and reference is made thereto for the purposes of this invention. For purposes of illustration and not limitation, reference is particularly made to pages 1-62 of Volume 12 of the Encyclopedia of Polymer Science and Engineering, 1988 revision, John Wiley Sons.

Polyamides which can be employed in the practice of the present invention include the various grades of nylon, such as nylon 6, nylon 66 and nylon 12.

Also included are lower molecular weight and lower viscosity polyamide copolymers which are used as hot-melt adhesives and which are well known in the art and are commercially available from numerous suppliers.

Polyolefins which can be employed in the practice of the present invention for preparing the multilayer laminate structure include polypropylene, polyethylene, and copolymers and blends thereof, as well as ethylene-propylenediene terpolymers. Preferred polyolefins are polypropylene, linear high density polyethylene (HDPE), heterogeneously branched linear low density polyethylene (LLDPE) such as DOWLEXTM polyethylene resin (a Trademark of The Dow Chemical Company) heterogeneously-branched ultra low linear density polyethylene (ULDPE) such as

ATTANE

T

M ULOPE (a Trademark of The Dow Chemical Company); homogeneouslybranched, linear ethylene/x-olefin copolymers such as TAFMERr (a trademark of Mitsui PetroChemicals Company Limited) and EXACT T (a trademark of Exxon Chemical Company); homogeneously-branched, substantially linear ethylene/a-olefin polymers such as AFFINITYT (a Trademark of The Dow Chemical Company) and ENGAGE T (a Trademark of du Pont Dow Elastomers polyolefin elastomers, which can be prepared as disclosed in U.S. Patents 5,272,236 and 5,278,272; and high pressure, free radical polymerized ethylene polymers and copolymers such as low density polyethylene (LDPE), ethylene-acrylic acid (EAA) copolymers such as PRIMACOR T (Trademark of The Dow Chemical Company), and ethylene-vinyl acetate (EVA) copolymers such as

ESCORENE

T polymers (a Trademark of Exxon Chemical Company), and ELVAX T (a Trademark of E.I, du Pont de Nemours The more preferred polyolefins are the homogeneously-branched linear and substantially linear ethylene copolymers with a density (measured in accordance with ASTM D-792) of 0.85 to 0.965 g/cc, a weight average molecular weight to number average molecular weight ratio (MJMo) from 1.5 to a measured melt index (measured in accordance with ASTM D-1238 (19012.16)) of 0.01 to 100 g/10 min, and an of 6 to 20 (measured in accordance with ASTM D-1238 (190/10)).

D e 43397 In general, high density polyethylene (HDPE) has a denslty of at least about 0.94 grams per cubic centimeter (ASTM rest Method D-1505). HOPE is commonly AMENDED SH1EET 43397 produced using techniques similar to the preparation of linear low density polyethylenes. Such techniques are described in U.S. Patents 2,825,721; 2,993,876; 3.250,825 and 4.204,050. The preferred HDPE employed in the practice of the present invention has a density of from 0.94 to 0.99 g/cc and a melt index of from 0.01 to 35 grams per 10 minutes as determined by ASTM Test Method D-1238.

Styrenics based on monovinyl aromatic monomers which can be employed in the practice of the present invention include polystyrene, polymethylstyrene, styrene-acrylonitrile, styrene-maleic anhydride copolymers, styrene/methylstyrene or styrene/chlorostyrene copolymers.

Other organic polymers which can be employed in the practice of the present invention for preparing the multilayer film include polyhexamethylene adipamide, polycaprolactone, polyhexamethylene sebacamide, polyethylene 2,6-naphthalate and polyethylene 1.5-naphthalate, polytetramethylene 1,2-dioxybenzoate and copolymers of ethylene terephthalate and ethylene isophthalate.

The thickness of the monolayer or multilayer film Is dependent on a number of factors, including the intended use, materials stored in the container, the length of storage prior to use and the specific composition employed in each layer of the laminate structure.

In general, the monolayer film will have a thickness of from 2.5 to 250 pm (0.1 to 10.0 mils), preferably from 5.08 to 127 prn (0.2 to 5.0 mils) and most preferably, 10.2 to 25.1 pm (0.4 to 1.0 mils). The multilayer film will have a total thickness of from 2.5 to 250 pm (0.1 to 10.0 mils), preferably from 5.08 to 127 pm (0.2 to 5.0 mils); with the thickness of the hydroxyfunctional polyether layer(s) being from 10 percent to 90 percent, and preferably 20 percent to percent of the total film thickness.

The metals which can be employed in the practice of the present invention for preparing the polymer-metal or polymer-metal-polymer laminate include tin plate steel (TPS), tinfree steel (TFS), electrochrome-coated steel (ECCS), galvanized steel, high strength low alloy steel, stainless steel, copper-plated steel, copper and aluminum. The preferred metals are tin plate steel and tin-free steel. Preferably, the metal is in the form of a flat sheet having two major surfaces.

For most metal packaging applications, the metal typically ranges from 76.2 to 508 pm (3 to 20 mils) in thickness, although the hydroxy-functional polyether film can be adhered to any gauge metal. It is within the scope of this present invention to laminate the hydroxyfunctional polyether film to thin metal foil such as 5.08 to 50.8 pm (0.2 to 2 mil) aluminum foil used in flexible packaging.

-11- AMENDED SHEET WO 99/32281 PCT/US98/22430 The polymer-metal or polymer-metal-polymer laminates of the present invention can be prepared by conventional lamination techniques. As is known in the art, specific laminating techniques include thermal lamination, that is, whereby an inherently melt activated adhesive film is heated and melt-bonded to a metal substrate by means of heat and pressure; or liquid coating and laminating, that is, whereby a separate adhesive such as a solvent-borne or aqueous-based adhesive is applied to the polymeric film or metal substrate at a desired thickness, the liquid driven off by a drying oven, and combining the film and the metal with heat and pressure to bond the two layers together. In a similar fashion to liquid coating, a hot-melt adhesive can be melted and applied by means of slot die coating or roll coating onto either the film or the metal and joining the two plies of film and metal together with pressure using the molten hot-melt adhesive to intimately bond the structure together, followed by cooling.

In general, a two-ply laminate comprising a polymer film layer and a metal layer can be prepared in accordance with the present invention by contacting one of the major surfaces of the metal layer with the polymer film at an elevated temperature with concurrent application of pressure. Similarly, a three-ply laminate comprising a polymer film layer, a metal layer and a polymer film layer is formed by applying to the remaining major surface of the metal layer another polymer film layer which is the same as or different from the other polymer film layer.

The polymer-metal or polymer-metal-polymer laminates can have any one of the following structures: a two-ply laminate comprising a first layer of a hydroxy-functional polyether (hydroxy-functional polyether) and a second layer of a metal; a three-ply laminate comprising a first outer layer of an organic polymer which is not hydroxy-functional polyether, a core layer of HPEE and a second outer layer of a metal; a three-ply laminate comprising a first outer layer of hydroxy-functional polyether, a core layer of an organic polymer which is not hydroxy-functional polyether and a second outer layer of a metal; -12- WO 99/32281 PCT/US98/22430 a three-ply laminate comprising a first outer layer of a hydroxy-functional polyether, a core layer of a metal and a second outer layer of an organic polymer which is not a hydroxy-functional polyether; and a three-ply laminate comprising a first outer layer of a co-extruded hydroxy-functional polyether/PETG film, a core layer of a metal and a second outer layer of an organic polymer which is not a hydroxy-functional polyether.

Preferably, the organic polymer which is not a hydroxy-functional polyether is polypropylene.

In the above structures, the organic polymer which is not a hydroxy-functional polyether (hydroxy-functional polyether) can be a blend of two or more different organic polymers.

The polymer-metal or polymer-metal-polymer laminates of the present invention are suitable for use in the manufacture of three-dimensional metal structures, such as, for example, aerosol containers and its various parts, where pressure sealing is obtained by forming a crimped edge with the polymeric layer tightly engaged between two layers of a steel sheet. Typically, an aerosol container comprises a can body or wall, which may be formed in one piece, or which may comprise a can body cylinder closed at its bottom end by an end member and at its top end by a domed cover member. The one-piece aerosol can body, or the domed cover member, has a mouth which is itself closed by a valve cup, carrying the aerosol dispensing valve. The valve cup is usually swaged on to the body. The polymer-metal or polymer-metal-polymer laminates of the present invention are particularly suitable for use in the manufacture of aerosol valve mounting cups, aerosol can domes and bottoms and can wall or body assembly.

In addition, the polymer-metal or polymer-metal-polymer laminates of the present invention may be employed in the preparation of other containers where a chemical, corrosion and pressure resistant seal is desired. Furthermore, in the manufacture of metal paint cans, the bottom of such cans may be stamped and formed from metal-polymer laminates and joined to the cylindrical sides of the can by formation of a crimped seal. The resulting seam is impervious to solvents and other chemicals shipped in the container and maintains a leak-proof seal. Formation of such metal cans using the components formed from the present metal-polymer laminate eliminates the need for separate application of a gasketing material such as an isoprene rubber around the perimeter of a circular-shaped blank and the curing thereof with its concomitant solvent emissions. Utilizing coated metals -13- S'-I ,yi. o 43397 according to the present invention streamlines the metal paint can manufacturing process, resulting in improved efficiency.

The polymer-metal laminates of the present invention can be deepdrawn into formed containers such as beverage containers or food packaging containers or metal bulk packaging containers. The thermoplastic nature of the hydroxy-functional polyether film allows the polymeric coating to sufficiently elongate and draw as the can structure is mechanically formed. Conventional thermoset coatings such as cured epoxy coatings are fairly brittle and will fracture upon significant elongation of the metal substrate.

such as occurs during deep drawing of 1-piece can bodies.

Additionally, large metal structures such as domestic appliance shells can be fabricated from the polymer-metal laminates of the present invention. Domestic appliances, which include refrigerator, washing machine, clothes dryer, and dishwasher, require exterior and interior surface finishes that are adherable to metal, and are formable, durable, scratch and abrasion resistant, solvent resistant, and aesthetically pleasing.

A

hydroxy-functional polyether (hydroxy-functional polyether) film laminate can replace the cured solvent-based primer and/or paint finish typically used with preformed postpainted appliance shells. The ductility and formability of pigmented hydroxy-functional polyether film-metal laminate permits the precoated coiled steel to be formed into the appliance shell without needing to be painted after forming." The following examples are for illustrative purposes only and are not intended to limit the scope of this invention. Unless otherwise indicated, all parts and percentages are by weight.

Example 1 A monolayer 0.8 mil (20 micron) hydroxy-phenoxyether (phenoxy) film was produced via conventional cast film extrusion using a phenoxy resin having a Tg of 100°C and a molecular weight of 50,000, available from Phenoxy Associates as PaPhen PKFE. The film was extruded at a melt temperature of225 0 C, quenched on a chill roll at further cooled to 30'C, and wound into a film roll. The 20 micron film was then separately thermally laminated onto pre-heated 267 micron (10.5 mil) tin plate steel at a temperature of 204 0 C using a continuous coil metal lamination process and then quenched to room temperature using forced air cooling, followed by water-cooled chill rolls. The phenoxy film exhibits excellent adhesion to the metal and could not be delaminated from the metal without cohesive failure (tearing) of the film at peel levels greater than 5.25 N/cm lb/inch).

-14- SRAtMENDED SHIEET 3J f JSLLLAA__ 77- I I-V j) 43397 Example 2 A two-layer coextruded 15 micron (0.6 MID) film was produced from a glycol-modifled copolyester (PETG), available from Eastman Chemical Company as PETG 6763 resin and a phenoxy resin (PaPhen PKFE). A conventional multilayered cast film line was used. The PEVG resin was extruded at a melt temperature of 225*C in one layer, while the phenoxy resin was extruded at 225 0 C in a second adjacent layer. The 15 micron film comprises a 60 percent PETG layer and 40 percent phenoxy layer, based on the film thickness. The coextruded two-layer film was quenched on a chill roll at 651C, further cooled to 30"C, and wound into a film roll. The 15 micron was then thermally laminated onto pre-heated 267 micron (10.5 mil) tin plate steel at a temperature of 20411C (400 0

F)

with the phenoxy layer bonded to the metal and then quenched to room temperature using forced-air cooling followed by water-cooled chill rolls. The phenoxy/PETG film could not be delarninated from the metal without destructive tearing of the film.

Physical Properties of Films of Example 1 2: Film MD Ullkate T DL1.1timate I MD%

TO%

Tensile Tensile Yield Yield M N/rn 2 M NIm 2 Elongation Eb-aion ex) MD% Ultimate Elongation Ex. 1 69.0 1 55.2 9 6 170 (10000 psi) 1. (8000 psi) F~A. 4 60.0 (8700 psi) 37.2 (.5400 _psi) 8 8 170 Physical Properties of Films of Example 1 2 (continued): Film TD% Ufta MID 2% 1TO 2% MD Elm. TD Elm.

Ekigti() Secant JSecant Tear Tea r Modulus Modulus Strength Strength MN/n 2 M Nn (q/pjrn (glujm) Spencer Impact Wgpm)

I

Ex 1 200 1909.9 1882.3 (273000 lsi) 305 330 I I (2T1O00oSi) EX. 2

I

1813.3 1703.6 (2M00pQ~ (251000psi) (12 glmil) (3g/mii) (295 g/mil~ 254 6858

HEI

*aJMn....jT. I jI I 43397 Example3 The two-layer phenoxy/PET- film of Example 2 was thermally laminated to a 267 micron (10.5 mil) tin plate steel at a temperature of 204 0 C (400 0 F) with the PETG layer contacting the preheated metal. The film exhibited excellent adhesion to the metal and could not be delariated.

ExaMcole 4 A monolayer film of a poly(hydroxy amino ether) (PHAE) resin was made on a conventional cast film line. The PHAE resin was produced from the reaction of the diglycidyl ether of bisphenol A (DGEBA) and monoethanolamine (MEA) followng the procedure described in U.S. Patent 5,275.853, and had a T 9 of 70r00 and a molecular weight of 60,000. The 12.7 micron (0.5 mil) film was extruded at a melt temperature of 210'C arnd quenched on a cooled casting roll at 65 0 C. prior to being further quenched to 0 C and wound into a roll. The film was thermally laminated to a 267 micron (10.5 mil) tin plate steel, a 5 mil aluminum and a 6 mil ECCS at a temperature of 2040C. In all three cases, the PHAE film exhibits excellent adhesion to metal and could not be peeled from the metal.

A two-layer coextruded film of PHAE and ethylene -acrylic acid (9 percent AA) was made via conventional cast film coextrusian. Both resins were extruded at 21011C and quenchec at 6511C prior to being further cooled to 30"C and rolled into a film roll. The 25.4 micron (1.0 mil) film was produced with a layer raiio of 50 percent of PHAE and percent of ethylene-acrylic acid (EAA). The film was then thermally laminated to a preheated tin plate steel at 20400, with the EPA layer of the coextruded film contacting and adhering to the steel. The film exhibited in excess of 5.25 N/cm (3.0 lbinch) adhesion to the metal and could not be peeled without destruction of the film.

Exmpe 6 A 15 mnicron (0.6 mil) biaxially oriented polyester (OPET) film was coated with a solvent-based phenoxy solution (40 percent phenoxy solids in methyl-ethyl ketone, available fromn Phenoxy Associates as UCAR PKH-S-40). A conventional liquid coater was used to apply the wet liquid coating to one side of the OPET film. The wet-coated film was then transported through a multizone hot air impingement drying oven (zone temperatures: to 150-F, 32-C to 651C) to dry off the solvent, leaving a 5.08 pm (0.2 mil) solid phenoxy layer on the -16mr (0.6 mil) OPET film. The 20.3 pm (0.8 mil) coated OPET film was then wound into a roll. The film was later thermally laminated onto pre-heated tin plate steel at 204°C using a coil metal lamination line, with the phenoxy layer adhered to the metal surface. The hot laminate was then quenched to room temperature using forced.air cooling and water-cooled chill rolls.

Example 7 The metal laminates of Examples 1, 2, 3, 4, 5 and 6 were drawn and formed into a 33 mm diameter by 12 mm deep cup using a Tinius Olsen Ductomatic

BUP

200 metal forming press. Cups with the laminate thin film on the outside of the cup and with the laminate thin film on the inside of the cup were produced, The thin films exhibitedexcellent adhesion to the formed metal with no film delamination observed.

Example 8 Multilayered metal laminates using the same pherioxy-based films of Examples 1,2,3 and 4 were produced with a coextruded 183 I m (7.2 mil) polypropylene (PP)-ultra linear low density polyethylene (ULLDPE) blend film simultaneously laminated onto the opposite side of the metal from the phenoxy-based film. The polypropylene film was a two-layer coextrusion with a 50 percent PP and 50 percent ULLDPE main layer percent of film gauge) and a maleic anhydride grafted polyethylene adhesive layer (15 percent of film gauge), which was made in accordance with the teachings of 20 U.S. Patent 5, 006,383. The 183pm PP film was laminated to the top side of a preheated 267 pm (10.5 mil) tin plate steel and the respective Example 1, 2, 3 or 4 phenoxy-based *:.film of 0.5 to 0.8 mil gauge was laminated to the bottom side of the steel. Thermal lamination was conducted at 204°C on a continuous coil steel lamination coating process.

After lamination, the two-sided coated steel was cooled, wound into a roll, and later slit to 25 desired widths. The slit narrow web coils ware later stamped into intricately shaped 25 mm diameter aerosol valve mounting cups (AVMC) using a commercial continuous 14-station multidie press. Each of the laminated structures exhibited good formability and drawability and no signs or film delamination. The aerosol valve mounting cups were then further converted into aerosol valve assemblies by the addition of a valve, actuator and stem 30 assembly using a commercial valve assembly operation.

The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge in Australia as at the priority date of any of the claims.

Throughout the description and claims of the specification the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.

17

Claims

1. A laminate structure comprising one or more layers of a metal and one or more layers of a hydroxy-functional polyether and, optionally, one or more layers of an organic polymer which is not a hydroxy-functional polyether, wherein said hydroxy-functional polyether layer bonds sufficiently to the metal to resist delamination from the metal layer without tearing of the hydroxy-functional polyether layer.

2. The laminate structure of claim 1 wherein said hydroxy-functional polyether layer exhibits a minimum of 3.5 N/cm (2.0 Ib/inch) adhesion to the metal layer.

3. The laminate structure of claim 1 wherein said hydroxy-functional polyether layer exhibits a minimum of 5.25 N/cm (3.0 Ib/inch) adhesion to the metal layer.

4. The laminate structure of claim 1 comprising a first outer layer of an organic polymer which is not a hydroxy-functional polyether, a core layer of a hydroxy-functional polyether and a second outer layer of a metal and, optionally, an adhesive layer interposed between the first outer layer and the core layer and/or between the second outer layer and the core layer.

5. The laminate structure of claim 1 comprising a first outer layer of 20 a hydroxy-functional polyether, a core layer of an organic polymer which is not a hydroxy-functional polyether and a second outer layer of a metal and, optionally, an adhesive layer interposed between the first outer layer and the core layer and/or between the second outer layer and the core layer.

6. The laminate structure of claim 1 comprising a first outer layer of 25 a hydroxy-functional polyether, a core layer of a metal and a second outer layer of an organic polymer which is not a hydroxy-functional polyether and, optionally, an adhesive layer interposed between the first outer layer and the core layer and/or between the second outer layer and the core layer.

7. The laminate structure of claim 6 wherein the organic polymer 30 which is not a hydroxy-functional polyether is polypropylene.

8. The laminate structure of claim 1 comprising a first outer layer of a hydroxy-functional polyether, a core layer of a metal and a second outer layer of a hydroxy-functional polyether and, optionally, an adhesive layer interposed between the first outer layer and the core layer and/or between the second outer layer and the core layer. 18 W:UanetlSPECIS39096.doc

9. The laminate structure of Claim 1 comprising a first outer layer of a hydroxy-functional polyether or a coextruded hydroxy-functional polyether/glycol-modiied copolyester (PETG) film, a core layer of a metal and a second outer layer of polypropylene and, optionally, an adhesive layer interposed between the first outer layer and the core layer and/or between the second outer layer and the core layer. The laminate structure of Claim 7 in the form of a three-dimensional metal structure.

11. The laminate structure of Claim 10 wherein the three-dimensional metal structure is an aerosol container, an aerosol valve mounting cup, a can bottom, a can wall, a beverage can, a food packaging can or a metal bulk packaging container.

12. The laminate structure of Claim 8 in the forrrrof a three-dimensional metal structure.

13. The laminate structure of Claim 12 wherein the three-dimensional metal structure is an aerosol container, an aerosol valve mounting cup, a can bottom, a can wall, a 15 beverage can, a food packaging can or a metal bulk packaging container.

14. The laminate structure of Claim 9 in the form of a three-dimensional metal structure.

15. The laminate structure of Claim 14 wherein the three-dimensional metal structure is an aerosol container, an aerosol valve mounting cup, a can bottom, a can wall, a 20 beverage can, a food packaging can or a metal bulk packaging container.

16. The laminate structure of Claim 14 wherein the polypropylene layer is laminated to the underside of the metal and the hydroxy-functional polyether or co-extruded hydroxy-functional polyether/glycol-modified copolyester (PETG) film layer is laminated to top surface of the metal.

17. The laminate structure of Claim 7 in the form of a large metal structure.

18. The laminate structure of Claim 17 wherein the large metal structure is a refrigerator, washing machine, clothes dryer, or dishwasher. I '19. The laminate structure of Claim 8 in the form of a large metal structure. -19- The laminate structure of Claim 19 wherein the large metal structure is a refrigerator, washing machine, clothes dryer, or dishwasher.

21. The laminate structure of Claim 9 in the form of a large metal structure.

22. The laminate structure of Claim 21 wherein the large metal structure is a refriqerator, washina machine, clothes dryer, or dishwasher.

23. The laminate structure of claim 1 substantially as hereinbefore described with reference to any of the examples. DATED: 15 February, 2002 PHILLIPS ORMONDE FITZPATRICK Attorneys for: THE DOW CHEMICAL COMPANY *oo S* *oo* 20