US 3860117 A
The elimination of the heretofore unsightly mottled appearance of skin packaged articles by interposing a thin blanket of powdered material between the contiguous surfaces of the article and the thermoplastic film by which the article is mounted on the display and carrying card of the package.
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United States Patent Walus et al.
[ METHOD OF SKIN PACKAGING AND PACKAGE RESULTING THEREFROM  Inventors: Richard L. Walus, Columbia Heights; Gary E. Olson, Brooklyn Center, both of Minn.
 Assignee: Possis Corporation, Minneapolis,
 Filed: Oct. 23, 1973  Appl. No.: 409,007-
 US. Cl. 206/461, 53/37  Int. Cl... B65d 75/42, B65d 75/46, B65d 83/04  Field of Search 206/461; 53/37, 30
PRODUCT [4 1 Jan. 14, 1975  References Cited UNITED STATES PATENTS 3,476,239 11/1969 Jacob 206/461 3,757,937 9/1973 Weinstein 206/461 Primary Examiner-George T. Hall  ABSTRACT The elimination of the heretofore unsightly mottled appearance of skin packaged articles by interposing a thin blanket of powdered material between the contiguous surfaces of the article and the thermoplastic film by which the article is mounted on the display and carrying card of the package.
17 Claims, 6 Drawing Figures mam JAN 1 3.860.117
' SHEET 20F 3 sum 3 0F 3 PATENTEU JAN 1 4l975 METHOD OF SKIN PACKAGING AND PACKAGE RESULTING THEREFROM This invention relates broadly to the packaging of articles or products by the technique known as skin packaging, and has as its purpose and object an improvement in the appearance of such packages.
Packages produced by the skin packaging technique customarily consist of a paperboard card with customer-attracting or product describing indicia printed on its front face, and the packaged article or product mounted on the card by a thin usually transparent thermoplastic film adhered to the front face of the card and drawn tightly over the packaged article or product.
As described in the Straub et al. US. Pat. No. 3,596,432, skin packaging can be practiced by different methods. With one method a heated sheet of thermoplastic material is draped over a number of the articles or products placed in spaced apart relationship on an air pervious panel, such as a sheet of cardboard, and then by means of suction applied to the underside of that panel, the heat-softened plastic sheet is drawn down over the articles or products and into firm engagement with the surrounding surface areas of the panel. To assure good adhesion between the panel and those portions of the plastic sheet in engagement therewith, the panel surface is usually treated to give it good affinity for the material of which the thermoplastic sheet is made.
In another method of skin packaging, for which the machine of the aforesaid Straub et al patent was developed, the articles or products to be packaged are sequentially deposited upon a traveling substrate which may be a web of paperboard drawn from a roll, or a series of discrete lengths of paperboard as in the Schuette Pat. No. 3,676,979, to be carried thereby through a descending curtain or sheet of molten thermoplastic material. As the molten material contacts the advancing substrate and the articles thereon, it congeals or freezes intoa thin film. Directly downstream from the nozzle by which the curtain is formed, the substrate passes over a vacuum chamber or suction nozzle by which the space between the covering thermoplastic film and the substrate is evacuated by virtue of the air pervious nature of the substrate.
In each of these two methods, the substrate with articles or products held thereto by the plastic film, is cut into sections, each of which forms one of the desired packages. To enable these packages to be conveniently displayed with a view to generating impulse buying at the retail level, the cards have holes in their upper portions by which they are hung on a display rack.
Obviously the sales appeal created by the packages thus displayed, to a major degree depends upon the attractiveness of the packages. If their appearance is in anywise less than pleasing, the hoped for sales stimulation will not be achieved. But, perhaps, even more important, a less than perfect appearance of the packaged article or part will inevitably have a damaging effect upon the reputation of the manufacturer thereof.
Unfortunately, for years the attainment of the desired appealing appearance has been thwarted by an unnaturally mottled appearance of the packaged articleor part. No matter how carefully the package was made, the surface of the article or part seen through the clear plastic film stretched thereover had a damaged appearance. Removal of the article or part from the package would reveal that it'had no surface imperfections; but unless the package sold itself to a customer, the lack of surface imperfections of the article or product would not be established.
It is quite evident, therefore, that the mottled appearance of an article or part prepared for retail sales by the skin packaging technique has been a serious matter with the industry. The search for a solution to this problem has claimed the attention of many experts in skin packaging, but until the advent of the present invention the problem was not solved.
Just what caused the mottled appearance is not fully understood. According to one theory, it resulted from localized air entrapment between the surface of the article or part and the overlying clear plastic film. The fact that the film and air have different light refraction indexes, gives credance to this theory.
It has also been thought that lack of uniformity in the tensioning of the film during the evacuation of the space beneath it, resulted in localized stressing of the plastic film, thereby creating areas of differing light refraction.
The inability to explain scientifically what caused the objectionable mottling, also makes it difficult to understand how or why this invention has overcome the problem. One thing, however, is certain it has been discovered that if contact between the contiguous surfaces of the article or part and the covering plastic film is prevented, the appearance of the packaged article or part is in no way impaired.
The manner in which the invention achieves its purpose will be appreciated from the following description and the accompanying drawings. This disclosure is in- A tended merely to exemplify the invention. The invention is not limited to the specific structure or method disclosed, and changes can be made therein which lie within the scope of the appended claims without departing from the invention.
Before proceeding with .the detailed description of the invention by reference to the accompanying drawings, it will no doubt be helpful'to'define briefly the method by which the invention achieves its purpose. In accordance with accepted skin packaging technique, and consideringthe packaging of only a single article or part, the article or part to be packaged is laid onto the paperboard card (substrate) to which it is to be attached. Now, before the thermoplastic film either preformed or formed in situ from a curtain of molten plastic issuing from a nozzle, as in the aforesaid Straub et al. or Schuette Pats. is laid onto the card and over the article, a thin blanket of finely powdered material is interposed between the film and the surfaces of the articles or part to which the film will be contiguous. This may be done by projecting (as by means of an air brush) an aerated dispersion of the powdered material onto all the surfaces of the article or part not in contact with the card or supporting substrate; or by projecting the aerated dispersion onto the underside of the plastic film before it is laid onto the substrate.
In either case, when the space beneath the plastic ing, avoids the formation of the objectionable mottled appearance. Because of the relatively rough surface of the porous substrate there is no such uniform spacing between the film and the substrate. In fact, since the particles of the powdered material enter the pores of the substrate, there are few areas in which the film is not tightly adhered to the substrate. FIG. 2 attempts to illustrate that condition.
There are a number of substances that can be used to form the thin blanket. Some of them are as follows: a dry fluorocarbon lubricant which is a active ingredient dispersion of white waxy tetrafluoroethylene telomer in a freon solvent; polyethylene; Teflon (which is a polytetrafluoroethylene); polypropylene; cornstarch; tapioca; and talcum powder. All of these materials have in common a high degree of lubricity and the capability of being reduced to a very fine particle size. Preferably the particle size of the material used should be on the order of five microns. A particle size greater than fifteen microns can give the plastic film a grainy fee], which may be undesirable.
No doubt there are other materials that can be used to form the intervening blanket, the identification of which would be well within the purview of anyone having a knowledge of the properties of pulverizable materials and which of such materials would be compatible with the thermoplastic material used in skin packaging.
Some of the listed materials are best applied in the dry state, while others must be a dispersion thereof in a liquid solvent. Thus, the cornstarch, tapioca and talcum powder are simply entrained in a pressurized stream of air which is projected onto the recipient surface or sufaces by an air brush. The other listed materials, in their pulverized state, are dispersed in an appropriate liquid carrier as for instance, freon for the fluorocarbon and the polyethylene, and water for the polypropylene and the resulting dispersion in an aerated state is similarly projected onto the recipient surface or surfaces.
In every .case, the layer or blanket which adhers to the recipient surface or surfaces is very thin and of a uniform layer of one particle thickness.
The application of the powdered material takes place in a zone connected with a source of suction that is strong enough only to withdraw the material that does not adhere to the recipient surface or surfaces. The withdrawn material is, of course, recycled.
The accompanying drawings illustrate two specific embodiments of the apparatus used in the practice of the invention, constructed in accordance with the best modes devised for the practical application of the principles thereof, and in which:
FIG. 1 is a perspective view of a package produced by the skin packaging technique, in accordance with this invention;
FIG. 2 is a cross-sectional view through the package shown in FIG. 1, on a greatly enlarged scale and with the thickness of the blanket of powdered material that is interposed between the contiguous surfaces of the thermoplastic film and the packaged article greatly exaggerated;
FIG. 3 is a perspective view of one embodiment of the structure that has been devised for the practice of this invention with the machines of the aforesaid Straub et al and Schuette patents;
FIG. 4 is a cross-sectional view through FIG. 3 on the plane of the line 4-4;
FIG. 5 is a sectional view through FIG. 4 on the plane of the line 5-5; and
FIG. 6 is a diagrammatic view illustrating another way of practicing the invention.
Referring to the drawings, the numeral 6 (FIG. I) indicates generally a package produced by the skin packaging technique in accordance with this invention. The package consists of a paperboard card 7 and the packaged article 8 held on the card by a thin transparent thermoplastic film 9 which covers the entire front face of the card and is drawn tautly about the article. As indicated, the card has suitable indicia printed on it and a hole 10 in its upper portion by which the package, along with other similar packages may be hung from pegs on a display rack.
Since thepackage 6 embodies the present invention, the contiguous surfaces of the article 8 and the thermoplastic film 9 are held out of contact by a thin layer or blanket 11 of powdered material possessing the lubricity and small grain size characteristic of the materials hereinbefore identified as suitable for the practice of this invention.
In FIGS. 3 and 4 one method of making the package is illustrated. In this method a series of air pervious cards 12, each having placed thereon two of the articles 8, is carried along a defined path by an endless conveyor 13. This conveyor like that of the Schuette Pat. No. 3,676,979, has grooves and ports (indicated in FIG. 3 but not shown in FIGS. 4 and 5) that enable the cards on the conveyor to be subjected to suction applied to the underside of the conveyor, and thereby held tightly thereon.
As the cards pass through a film applying station 14, a descending curtain or stream of molten thermoplastic material descends upon the advancing cards and forms a film which covers'the articles and the surrounding surface areas of the cards. The molten thermoplastic material issues from a nozzle (not shown) which is preferably like that of the Straub et al. Pat. No. 3,596,432. Downstream from the station 14, the film is drawn down onto the cards and tautly about the articles by evacuating the space beneath the film with a suction nozzle or vacuum chamber (not shown) as in the Schuette patent. Beyond the location at which suction is applied to the underside of the film, the cards may be slit to form two packages, and a hole 10 punched into each card.
The procedure and apparatus thus far described is essentially that of the Schuette patent, but in accordance with this invention, the cards with thearticles thereon pass through a powder applying station 15 before they reach the film applying station. The apparatus at the powder applying station comprises an arched hood 16 having legs 17 by which the hood may be suitably mounted on the stationary frame of the machine, and a top wall 18. The hood straddles the path along which the conveyor carries the cards, and extends along this path for a distance great enough to assure that the articles on the cards will be in the hood long enough to be coated with powdered material issuing from a pair of air brushes 19 as aerated streams or sprays indicated by broken lines in FIG. 4. The air brushes are of course suitably mounted and are positioned to assure that all surfaces of the articles not actually in contact with the cards will have powdered material applied thereto. The surrounding surfaces of the cards, will of course also be coated.
Hoses 21 connect the air brushes 19 with a tank 22 which contains a supply of the powdered material, and other hoses 23 connect the air brushes with a source of pressurized air, by which the powdered material (either in the dry state as in the case of cornstarch, or as a liquid dispersion of the selected material) is educed and projected as an aerated spray from the air brushes.
Excess powdered material is withdrawn by suction from the hood 16 through a duct 24 which connects an outlet port 25 in the top wall of the hood with a separator 26 in which the excess material accumulates to be recycled. As seen in FIG. 5, the outlet port 25 does not open directly to the hood interior but rather through a branched withdrawal passage 27, the entrances 28 of which are located upstream and downstream of the area onto which the air brushes project the powdered material.
Since there is no point in having the air brushes in action when no articles or parts to be packaged are in position to be coated, they are in effect turned on and off as the articles enter and leave the target area onto which the air brushes are trained. This can be done in any suitable way, as by strategically located photo-cells indicated at 29 in FIG. 3, that provide input signals to adjustable control instrumentalities 30.
While it may be preferable to provide the spacing blanket 11 by coating the articles in the manner just described, it can also be done by projecting the material onto the underside of the film before it is laid onto the substrate and over the articles thereon, as diagrammatically depicted in FIG. 6. As there shown, preformed thermoplastic film 31 is drawn from a roll 32 and around a positioning roller 32' located a short distance above the path of the traveling substrate 33 by which the articles are carried through the machine. Downstream from the roller 32 the film lays itself onto the substrate and then passes under a heat source 34 which softens the film sufficiently to enable it to be drawn tautly about the articles and onto the substrate by evacuation of the space beneath the film.
The blanket of powdered material is applied to the underside of the film preferably by air brush means 35 positioned to project the material onto the film as it moves towards the roller 32'.
The net result of the operation depicted in FIG. 6 is the same as that accomplished with the apparatus shown in FIGS. 3-5, for in each case the thin thermoplastic film by which the articles are held on the display card, is uniformly spaced from all surface areas of the articles contiguous to the film.
Those skilled in the art will appreciate that the invention can be embodied in forms other than as herein disclosed for purposes of illustration.
The invention is defined by the following claims:
1. In the method of skin packaging of articles wherein a thin substantially clear thermoplastic film laid onto an air pervious substrate bearing the article to be packaged is drawn tautly about the article and onto the surface of the substrate surrounding the article to thereby secure the article to the substrate, by evacuating the space between the film'and the substrate through the air pervious substrate, the improvement which assures a uniform unmottled appearance for the packaged article, and which improvement is achieved by spacing the thermoplastic film from the surface of the article by interposing therebetween a thin blanket of finely powdered material that is not incompatible with the thermoplastic film and has good lubricity and the capability of being reduced to very fine grain size.
2. The invention defined by claim 1, wherein said thin blanket of finely powdered material is applied to the surface of the article before the thermoplastic film is laid thereon.
3. The invention defined by claim 1, wherein said thin blanket of finely powdered material is applied to the underside of the thermoplastic film before it is laid onto the substrate.
4. The invention defined by claim 1, wherein said thin blanket of finely powdered material is formed by projecting an aerated dispersion thereof onto all surfaces of the article not in contact with the substrate, before the film is laid thereon.
5. The invention defined by claim 1, wherein said thin blanket of finely powdered material is formed by projecting an aerated dispersion thereof onto the underside of the film before it is laid onto the substrate.
6. The invention of claim 1, wherein the substrate with the article thereon is moved along a defined substantially horizontal path that crosses an evacuation station at which the film is drawn down onto the substrate and about the article thereon, wherein the film is laid onto the substrate and the article thereon at a location upstream from the evacuation station, and wherein said thin blanket of finely powdered material is interposed between the film and the article by projecting an aerated dispersion of the powdered material onto one of them as the article, traveling with the substrate, approaches the location at which the film is laid onto the substrate and over the article thereon.
7. The invention of claim 6, wherein the aerated dispersion of the powdered material is projected onto all surfaces of the article not in contact with the substrate.
8. The invention of claim 6, wherein the aerated dispersion of the powdered material is projected onto the underside of the film before it is laid onto the substrate and the article thereon.
9'. The invention defined by claim 6, further characterized by subjecting the zone in which projection of the aerated powdered material takes place to suction so that the powdered material in excess of the amount thereof needed to coat the surface onto which it is projected can be recycled.
10. The invention defined by claim 1, wherein said powdered material has a particle size not in excess of fifteen microns.
11. The invention defined by claim 10, wherein the particle size of the powdered material is on the order of five microns.
12. The invention defined by claim 1, wherein the powdered material constituting said thin blanket has the characteristics common to dry fluorocarbon lubricant, polypropylene, polytetrafluoroethylene, polyethylene, tapioca, cornstarch and talcum powder.
13. The invention defined by claim 1, wherein the powdered material constituting said thin blanket is chosen from the class consisting of dry fluorocarbon lubricant, polypropylene, polytetrafiuoroethylene, polyethylene, tapioca, cornstarch and talcum powder.
14. An improved package produced by the skin packaging technique, comprising, a substrate; the packaged article; a substantially transparent plastic film adhered to the surface of the substrate surrounding the article and snugly embracing the article to hold the same on the substrate; and means to assure an unmottled apthe characteristics common to dry fluorocarbon lubricant, polypropylene, polytetrafluoroethylene, polyethylene, tapioca, cornstarch and talcum powder.
17. The invention defined by claim 14, wherein the powdered material constituting said thin blanket is chosen from the class consisting of dry fluorocarbon lubricant, polypropylene, polytetrafluoroethylene,
polyethylene, tapioca, cornstarch and talcum powder. l i
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