Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Physical dimension specified
Reexamination Certificate
1998-03-25
2003-02-25
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Physical dimension specified
C428S035300, C428S035400, C428S035800, C428S036600, C428S457000, C428S458000, C428S461000, C428S465000, C428S467000, C427S250000, C427S255600, C427S255700
Reexamination Certificate
active
06524698
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to improvements in composite sheets in general (hereinafter called foils for short), and more particularly to improvements in foils wherein at least one side of a substrate (e.g., a strip or web of plastic material) is coated with a metallic film, such as a film of aluminum. The invention also relates to a method of making foils which contain metallic films.
Foils of the above outlined character are in widespread use in a number of industries, particularly for the packing or wrapping of foodstuffs and many other products. An advantage of foils which consist of or include metallized substrates is that they enhance the appearance of the packed or wrapped products. Another advantage of such foils is that their initial as well as processing cost is but a fraction of the cost of foils which are made solely of a metallic material, such as aluminum. A further important advantage of foils wherein a usually nonmetallic substrate carries one or more films of metallic material is that they can be provided with one or more additional coats in a simple, time-saving and inexpensive manner.
A drawback of presently known foils wherein a substrate carries one or more films of metallic material is that they are not suitable for a number of important uses. For example, foodstuffs of many kinds, as well as many cosmetic substances, must be packaged or wrapped in such a way that the contents of the package are reliably sealed from the surrounding air as well as from moisture. Heretofore known attempts to produce foils which satisfy such requirements include the utilization of plastic substrates which are laminated with films of a metallic material, such as, aluminum. It is also known to coat metallized plastic foils with layers of polyvinylidene chloride. A drawback of such foils is that they are expensive as well as that they do not satisfy the exacting requirements of environmental protection agencies in many countries. Another drawback of such foils is that they are not fluidtight, or are not sufficiently fluidtight, for a number of purposes. Moreover, their ability to prevent the penetration of gaseous and/or liquid fluids is not predictable and often varies from area to area. While the inability of such conventional foils to prevent the passage of certain gases and/or vaporized liquids might not be detrimental for a number of uses, their permeability to oxygen and/or vapors (such as water vapors) renders them unacceptable for a number of important applications in the food processing and many other industries. Extensive and costly research in this field has so far failed to provide a solution which would broaden the field of application of metallized foils. Moreover, the permeability of conventional foils to oxygen and to certain other fluids increases drastically if their metallic films are permitted to rub against each other and/or against the substrates and/or against the confined product or products.
OBJECTS OF THE INVENTION
An object of the invention is to provide a foil which is not permeable to fluids.
Another object of the invention is to provide a foil which can be put to use as any conventional foil and is further suitable for a number of additional important uses.
A further object of the invention is to provide a foil which meets the requirements of environmental protection agencies and which can be utilized with advantage for the wrapping or packing or other confinement of all kinds of foodstuffs, cosmetics and many other products that should be sealed from the surrounding atmosphere.
An additional object of the invention is to provide a foil which is formed in such a way that its metallic layer or layers are reliably protected from scuffing, corrosion and/or other undesirable influences.
Still another object of the invention is to provide a foil which can be stored in convoluted form without any damage to its metallic film or films.
A further object of the invention is to provide a foil which can be made of readily available materials, at a low cost and in readily available machinery.
Another object of the invention is to provide a foil which is more versatile and safer than heretofore known foils even though its thickness need not exceed, and can be less than, the thickness of conventional foils.
An additional object of the invention is to provide a foil which can readily accept and retain printed matter.
Still another object of the invention is to provide a novel and improved method of making the above outlined foil.
A further object of the invention is to provide a method which renders it possible to reinforce and/or otherwise improve the appearance and/or other desirable characteristics of the basic substrate-metallic film combination in a number of different ways, to a desired extent and in a simple and time-saving manner.
Another object of the invention is to provide a method which renders it possible to convert a basic foil consisting of a substrate and one or more metallic films into a superior foil in a simple, inexpensive and timesaving way.
An additional object of the invention is to provide an apparatus for the practice of the above outlined method.
SUMMARY OF THE INVENTION
One feature of the invention resides in the provision of a foil which comprises a substrate having a first side and a second side, a metallic film which adheres to at least one side of the substrate and has a surface facing away from the one side of the substrate, and a protective layer which overlies and adheres to the entire surface of the film. The layer preferably contains or consists of an organic material which strongly adheres to the surface of the film. Such organic material can have a molecular weight of at least about 10,000 g/mol or a molecular weight of less than about 10,000 g/mol. The organic material can be selected from the group consisting of natural and synthetic resins and natural and synthetic waxes and lubricants. For example, the organic material can contain a resin for lacquers and varnishes, a non-smearing wax or caoutchouc. Furthermore, the organic material can constitute a priming which facilitates the application of printed matter to the protective layer. Even furthermore, the layer is substantially no-smearing.
The layer is preferably thin, most preferably very thin. For example, the layer can have a thickness of about 0.5&mgr; to about {fraction (1/15,000)} mm. Such layer is preferably applied to the metallic film while the latter is still devoid of scratches and/or other defects which would render the film permeable to gases. For example, the metallic material of the film can be vaporized onto the one side of the substrate and the organic material of the protective layer can be vaporized onto successive increments of the freshly vaporized film. A metal film is generally considered free of scratches if the film does not have uneven areas which are noticeable in light transmission. For example, in transmission, a foil which has pin windows is covered with small illuminated dots. The lower the number of such mechanical defects in the metal film, the less pervious the foil is to gases. A protective coating made of an organic material which is applied immediately after coating the metal film and which has a high affinity to the metal, reduces the permeability of the foil to gases to {fraction (1/10)} of that of an unprotected metal film.
The protective layer and the film can jointly constitute a fluidtight coating at the one side of the substrate. Furthermore, the layer can be resistant to corrosion, i.e., it can prevent oxidation of the metallic film.
The layer is preferably made in such a way that its thickness is constant along the entire surface of the film. Furthermore, the protective layer can be resistant to blocking. The organic material of the layer preferably exhibits high affinity for the metallic material of the film, and the layer is preferably made of an imprintable material.
The foil can further include a coating which overlies and adheres to the protective layer. The coating can constitute an extrusion which
Norris McLaughlin & Marcus P.A.
Yamnitzky Marie
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