US2326955A - Coated foil - Google Patents

Description

Aug. 17, 1943. E'. I .MACK ET AL *Y 2,326,955,

COATED FOIL Filed June 11, 1938 Y INVENToRs Edmrd L Marl av'alkj arse ATTORNEY Patented Aug. 17, 1943 UNITED STATES PATENT 'OFFICE COATED FOIL Edward L. Mack, Douglaston, N. Y., and Earle H. Morse, ,Nutley, N. J., assignors to Reynolds Research Corporation, Richmond, Va., a corporation of Delaware Application June 11, 1938, Serial No. 213,160

16 Claims.

This invention relates to a new Aand improved product comprising a coated metal foil and par- -ticularly relates to an unannealed or partially annealed foil of aluminum coated -with a. thin layer of preferably transparent resilient material such as rubber or Vistanex, a polymerize'd straight chain petroleum hydro-carbon, which is in turn overcoated with a. cellulose derivative lm such as cellulose acetate plus an appropriate plasticizer, or generally similar nlm having like qualities, and to a method of forming such coated foils. Vistanex is the trade-name for a polymerized straight chain hydrocarbon, namely, polyisobutylene, and is a substantially permanently tacky adhesive of relatively high viscosity Vwhich issubstantially non-oxidizable at normal room temperature. In the practice of the invention those equivalents of` cellulose acetate which are recognizedxinv the art`may be employed.

Heretofore annealed metal foils particularly aluminum foils of thin gauge have often been found inappropriate for use with the high speed packaging methods which it is desired to use in packaging various consumer goods as the foil web tends to rupture and to break. It has been found a distinct advantage to have the foil wrapping material as strong as possible. Various 'coatings have been applied to foils but in many instances such coatings do not adhere ilrmly to the highly polished surface of the metal foil. When unannealed aluminum foil is used, a1-` though it is stronger it has. an unpleasant rattle, is brittle and hard, and cracks and crinkles.. This applies also to unannealed zinc foil. vThe edges of unannealed foil also are likely to cut the fingers of persons handling the same. Partially annealed foil is stronger than fully annealed foil but naturally in part has the undesirable attributes of unannealed foil.

Therefore, it is an object of our invention-to provide a new and novel product, namely apartly annealed or unannealed aluminum, aluminumzinc, or zinc foil, or metal foils-of like attributes which is coated with a thin layer of resilient rubber-like transparent Vmaterial such as rubber or Vistanex, which layer is in turn overcoated with 'a I ayer of cellulose derivative or film of like n qualities, such .new metal foil product having extremely desirablenew characteristics including lessened rattle, increased strength, a smooth and r soft handling effect includingan attractive draping quality, an increased luster andalso a desirable-folding characteristic in that after it has by weight in gasoline, thus applying a coating' tive base layer is rendered thermoplastic in character for its obviously desirable heat sealing quality -so that packages may be sealed merely by application of heat and pressure and without the employment of an additional adhesive.

It is a further object 'of our invention to provide such a. coated foil with printing matter underneath the coating by applying the printing matter to selected areas of the foil before coating the same; if desired the cellulose derivative base layer can be printed upon directly.

It is still a further object of our invention to continuously produce such coated foils by an eiiicient, rapid, and veconomical method as hereinafter described.

These and various other objects and advantages will be readily understood from the following description taken in connection with the accompanying drawing of preferred embodiments in the invention, in which modications may be made without departing from the scope of the appended claims. A

In the drawing:

Fig. 1 is-a diagrammatic showing of an appa-A ratus for the production of a coated metal foil 'made inaccordance with our invention.

AFig. 2 is a cross-section of a coated foil illustrating an embodiment of our invention. In these'tlgures, a roll of unannealed aluminum foil III is carried upon a spool I2. .The aluminum foil in this example may beof .0007" thick and the web Il of aluminum foil is led over guide roller I6 to a Vistanex applicatorV roll` I8 revolving in a bath 20 of Vistanex solution comprisedpreferably of 5% solution of Vistanex 20A of Vistanex to the foil web I4, which layer or coating of Vistanex when dry may be .000 f' thick. The coated web is led into lowerl compartment 22 of the drying apparatus indicated generally as 24, and the volatile solvent is driven off, leaving a tacky rubbery-like transparent Vistanex coating; it is diicult if not impossible to roller-coat the cellulose derivative base coating upon the tacky Vistanex. For commercial production spray coating, or coating with relatively high viscosity solutions from a wide slit- I like extrusion nozzle slightly spaced from web Il, as described and claimed in our colpending application, Serial No. 148,382, Method and apparatus for forming films and nlm coatings, is desirable. Therefore, the coated foil .is preferably led over roller 26. Extrusion nozzle 28 of pressure hopper 28A is slightly spaced, say from roller `2li and cellulose derivative base solution 30 is forced through nozzle 28, overco'ating if desired, in -the cellulose derivative coating sullcient plasticizer so that the cellulose yderiva-- the Vistanex coating 20A with a layer of cellulose derivative base lm 30A. Alternately spray- Acoating methods may be. utilized for coating the cellulose derivative layer upon the Vistanex coating.

The cellulose derivative base solution 30 may comprise about 25 parts oi' cellulose acetate, 10 parts of dimethyl phthalate by weight and 65 parts of acetone by weight and coatings of cellulose derivative base film of .0007" have been found to give a particularly satisfactory product. TheI web I4 is then led over guide roller 32 through upper compartment 34 of t'ne drying apparatus 24 where the acetone is driven off, past guide roller 36 to the rewind 38, thus giving a coated unannealed metal foil which includes a layer of foil .0007 thick, a layer of Vistanex .0002" thick co-extensive therewith, and a layer of cellulose derivative base m .0007" thick overlying the layer of VistaneX.

If it is desired to make the cellulose derivative layer "heat sealing or thermoplastic with moderate heat, various plasticizers may be employed, but we have found that 25 parts of cellulose acetate, 18 parts dimethyl phthalate, and 57 parts acetone, by weight, serve satisfactorily. v

It will be recognized that various foil gauges may be advantageously employed to form a new and improved foil wrapping material made in accordance with our invention; foil ranges will ordinarily vary between .0005" thick to .002 thick with the Vistanex" and cellulose derivative coatings proportionately varying in thickness for various desired effects. I'he Vistanex" may vary between .0001" thick to .0005" thick, and the cellulose derivative layer may vary'between .0005" thick to .002" thick. Also, various resilient rubbery materials, preferably transparent, may be substituted for the Vistanex, such as rubber dissolved in an appropriate solvent, for exam'ple a volatile hydrocarbon. Of course, dependent upon the method of coating employed, solutions oi various viscosities may be utilized, as will be recognized by those skilled in the art. The cellulose derivative layer tends to adhere rmly v to the Vistanex layer which latter is soft and rubbery and tends to be tacky; a further advantage is that foils which have some' traces of oil from rolling can be employed as a base for our new product, without cleaning, because of' the adherent qualities of Vistanex A coated unannealed or partially annealed foil made as described ha." a high luster, is strong for use in packaging machinery, has good foldability,.

is sound-deadened by particularly the Vistanex layer, and the coatings are exceptionally adherent one to another and to the foil. While the new product described includes a coated thin metallic foil of high temper, such coatings applied to low temper foils strengthen the foil, give a high luster, and are firmly adherent. Ii.' desired the foil may be printed upon inl selected areas before being coated, or the printing may be applied to the cellulose derivative base film.

It will be understood that while the illustrated forms of the invention which we have described.

represent certain preferred embodiments, we do not wish to limit ourselves to the details as shown since it, is obvious that the same maybe widely varied without departing from the spirit of the invention as described and claimed-inv the ap, pended claims.

We claim:

1. As a .new product a thin metal foil of relatively` high temper, a vcoating of Vistanex" thereupon and an overcoating of cellulose derivative film upon the said Vistanex coating.

2. The product as dened in claim 1 wherein lthe foil is unannealed aluminum foil.

3. The product as dened in claim 1 wherein the foil is partially annealed aluminum foil.-

4. The product as defined in claim l vwherein the foil is unannealed zinc foil.

5. The product as ,defined in claim 1 wherein the foil is partially annealed zinc foil.

6. As a new wrapping material having improved strength and luster, a thin metal foil of relatively high temper, a relatively permanently tacky, elastic, flexible, resilient, transparent, firmly metal adherent coating co-extensive therewith, and an overcoating of cellulose derivative base film upon said transparent coating.

'7. A wrapping material as defined in claim 6 wherein the said transparent coating is rubber.

8. A wrapping material as defined in claim 6 wherein the said transparent coating is Vistanex.,

9. A wrapping material as defined in claim 8 wherein the foil is not more than partially annealed aluminum foil of a thickness between .0005"-.002" and wherein said-transparent coating comprises Vistanex of a thickness between .0001.0005" and wherein said cellulose derivative layer is of a thickness between .0005"-.002".

10. A wrapping material'as dened in claim 6 wherein said cellulose vderivative film includes a plasticizer and is thermoplastic under moderate heat conditions so that the same is '"heat sealing.

11. As a new wrapping material having irnproved strength and luster, a metal foil, a relatively permanently tacky, elastic, ilexible, resilient, transparent, tenaciously metal adherent coating co-extensive therewith, and an Overcoating of cellulose derivative base film upon said transparent coating.

12. A wrapping material as defined in claim 11 wherein said cellulose derivative base film includes a plasticizer and is thermoplastic under moderate heat conditions so that the same is .heat sealing.

13. A new wrapping material which includes a metal foil of relatively high temper, a first layer' of relatively permanently tacky, elastic, flexible, resilient highly adhesive transparent material superposed thereupon, and a second layer of cellulose derivative base film superposed upon said first layer. Y

14. A material as defined in claim 13 wherein said rstlayer is tacky at ordinary room temperatures and said second layer is thermoplastic under moderate heat conditions so that the same is heatsealingn 15. As a new wrapping product, a thin flexible metal foil between .0005"-.002" thick normally having a crackle or rattle, a relatively permanently tacky metal adherent, flexible, resilient, elastic, continuous film coating between .000l.0005" thick'thereupon, and a. thin overcoating of cellulose derivative film between .0005" to .002" thick upon said first permanently tacky coating, whereby the rattle of the foil is substantially lessened and the same has improved creasing, draping and strength characteristics.

16. A product as defined in claim 15, wherein the permanently tacky film coating is Vistanex.

' EDWARD L. MACK. EARLE H. MORSE.

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