Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
2001-05-30
2003-11-18
LaVilla, Michael (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C428S336000, C428S458000, C428S461000, C428S516000
Reexamination Certificate
active
06649279
ABSTRACT:
BACKGROUND
The invention relates to polymer films. More precisely, the present invention relates to multilayer, metallized polyolefin film structures that (a) exhibit excellent barrier properties, such as low water vapor transmission and low oxygen transmission properties, and (b) possess the necessary functionality both to protect the metallized layer and be receptive to surface printing and overlacquering, thereby rendering the present film structures (c) suitable for monoweb packaging applications.
Films to be used in food packaging applications desirably exhibit superior barrier properties that make the films as resistant as possible to the transmission of, for example, moisture and air.
Over the last decade, there has been an explosive growth in the use of metallized polymer films for packaging applications in general, and food packaging applications in particular. Metallized oriented polypropylene (OPP) and metallized oriented high-density polyethylene (OHDPE) exhibit improved food packaging properties, such as low light, oxygen, and water-vapor transmission properties, in comparison to unmetallized OPP and OHDPE. Packages made from metallized OPP or metallized OHDPE possess improved aesthetics due to their rich, metal-like appearance.
Typically, metallized OPP or metallized OHDPE is formed by vacuum depositing a thin layer, i.e. from about 100 Å to about 600 Å thick, of aluminum onto the surface of a clear OPP or OHDPE base film substrate. The deposited aluminum layer is particularly sensitive to damage, e.g. scratching, pinholes, and/or pickoff, and damage to the aluminum layer results in a deleterious effect on both the film's barrier properties and aesthetic properties.
Consequently, metallized OPP or metallized OHDPE films are conventionally used in an adhesive or polymount lamination, wherein the aluminum surface is protected by being buried in the lamination. For example, metallized OPP may be laminated to a clear OPP or oriented polyethylene terephthalate (OPET) film. Generally, the clear OPP or OPET film is reverse printed prior to being laminated to the metallized OPP. The printing allows for the necessary product details to be prominently displayed on the outside of the package. Thus, the reverse printed clear web faces the outside of the package and the metallized film with the aluminum layer buried in the lamination faces the inside of the package. Additionally, the surface of the metallized film opposite the aluminum surface is generally heat sealable or suitable for use with a cold seal, such that the finished package may be sealed to hold the product.
U.S. Pat. No. 5,194,318 discloses a metallized oriented film combination having a propylene polymer substrate with a high density polyethylene skin layer on at least one side thereof and a thin metal layer deposited on the surface of the high density polyethylene. The surface of these metallized oriented film combinations may be scratched and damaged resulting in a loss of barrier properties and aesthetics. Furthermore, the combinations are not directly suitable for surface printing.
U.S. Pat. No. 5,525,421 discloses a metallized film comprising an oriented polypropylene substrate having at least one surface coated with a vinyl alcohol homopolymer and a metal layer deposited thereon.
U.S. Pat. No. 5,591,520 discloses an oriented film combination of (a) a base layer of polypropylene, at least one surface of which comprises a maleic acid anhydride modified polypropylene; (b) on the at least one surface, a skin layer of an amorphous polyamide or a blend of an amorphous polyamide and a semicrystalline polyamide; and (c) a metal layer deposited on the polyamide skin layer. The surface of these oriented film combinations may be scratched and damaged resulting in a loss of barrier properties and aesthetics. Furthermore, the combinations are not directly suitable for surface printing.
U.S. Pat. No. 5,827,615 discloses a metallized multilayer film comprising either an OPP or an OHDPE core layer, maleic anhydride-modified polyolefin, which is either blended with the base polymer of the core layer or formed into an adhesion-promoting tie layer, and a metal receiving skin layer of an ethylene vinyl alcohol copolymer (EVOH), which is formed either on the maleic anhydride-modified polyolefin adhesion-promoting tie layer or on the maleic anhydride-containing core layer. A metal layer is deposited on the metal receiving skin layer. According to the '615 patent, it is essential to use a maleic anhydride-modified polyolefin in order to tie the core layer with the EVOH copolymer layer.
Application Ser. No. 09/490,477 filed Jan. 24, 2000, by Migliorini, et al., relates to improving the barrier properties of metallized films as opposed to the direct printability and scratch resistance of the metal deposit layer.
SUMMARY
There is provided a metallized multilayer film structure comprising:
(a) a core layer comprising a film-forming polyolefin selected from the group consisting of isotactic propylene homopolymer, high density polyethylene (HDPE), and linear low density polyethylene (LLDPE), the core layer having a first side and a second side;
(b) a metal receiving skin layer on the first side of the core layer, wherein the metal receiving skin layer comprises a film-forming polyolefin selected from the group consisting of high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), ethylene-propylene random copolymer, ethylene-propylene-butylene terpolymer, propylene-butylene copolymer, propylene homopolymer, and blends thereof;
(c) a metal layer deposited on the surface of the metal receiving skin layer opposite the core layer;
(d) a topcoat layer on the surface of the metal layer opposite the metal receiving skin layer, the topcoat layer comprising a coating selected from the group consisting of an ethylene acrylic acid copolymer (EM) coating, an ethylene methacrylic acid copolymer (EMA) coating, an acrylonitrile coating, a urethane coating, an epoxy coating, and blends thereof; and
(e) a polymer skin layer on the second side of the core layer, the polymer skin layer comprising a film-forming polyolefin selected from the group consisting of ethylene-propylene random copolymer, ethylene-propylene block copolymer, ethylene-propylene-butylene terpolymer, and propylene-butylene copolymer.
There is also provided a metallized multilayer film structure comprising:
(a) a core layer comprising isotactic propylene homopolymer, the core layer having a first side and a second side;
(b) a tie layer on the first side of the core layer, the tie layer comprising a maleic anhydride-modified polypropylene or a maleic anhydride-modified ethylene-propylene copolymer;
(c) a metal receiving skin layer on the surface of the tie layer opposite the core layer, wherein the metal receiving skin layer comprises either a film-forming amorphous polyamide or a film-forming blend of an amorphous polyamide and one or more semicrystalline polyamides;
(d) a metal layer deposited on the surface of the metal receiving skin layer opposite the tie layer;
(e) a topcoat layer on the surface of the metal layer opposite the metal receiving skin layer, the topcoat layer comprising a coating selected from the group consisting of an acrylic coating, an ethylene acrylic acid copolymer (EAA) coating, an ethylene methacrylic acid copolymer (EMA) coating, an acrylonitrile coating, a polyvinylidene chloride (PVdC) coating, a polyvinyl alcohol (PVOH) coating, a urethane coating, an epoxy coating, and blends thereof; and
(f) a polymer skin layer on the second side of the core layer, the polymer skin layer comprising a film-forming polyolefin selected from the group consisting of ethylene-propylene random copolymer, ethylene-propylene block copolymer, ethylene-propylene-butylene terpolymer, and propylene-butylene copolymer.
The present metallized multilayer film structure may optionally contain a primer layer interposed between the topcoat layer and the metal layer.
The present metallized multilayer film struc
Mallory William M.
Migliorini Robert A.
Osgood, Jr. Wayne Robert
Parr Larry A.
Bell Keith A.
ExxonMobil Oil Corporation
James Rick F.
LaVilla Michael
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