US 3031072 A
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April 24, 1962 H. G. KRAUT 3,031,072
PACKAGE AND METHOD OF FORMING SAME Filed Jan. 29, 1960 2 Sheets-Sheet 1 INVENTOR. HERMAN G- KRAUT BY Q; 46W
TORNEYS April 24, 1962 H. s. KRAUT PACKAGE AND METHOD OF FORMING SAME 2 Sheets-Sheet 2 Filed Jan. 29, 1960 FIG. 4
INVENTOR. HERMAN G. KRAUT A OPNEYS FIG. 6
United States Patent Ofiice The present invention relates to an improved package for holding an article of merchandise on a card with the article covered with a protective transparent covering, and also relates to the method of making the package. More particularly, the invention is directed to a package for articles of merchandise such as items of hardware and the like wherein the article is secured to a card by a closely fitting transparent covering web or sheathing formed of thermoplastic sheet material which overlies the card and is secured thereto byits own substance, and to the method of forming such a composite package.
This application is a continuation-in-part of my copending application Serial No. 793,889, filed February 17, 1959, now abandoned.
The packaging of articles on cards with transparent coverings is particularly advantageous from a merchandising standpoint because the articles packaged in this way are easy to handle and they are protected against damage and loss from the time the articles leave the manufacturer until they reach the ultimate consumer. At the same time, the articles are attractively displayed for visual inspection by the prospective purchaser, thus enhancing sales.
An aim of the present invention is to provide an article package of the type referred to and a method of making same without the use of adhesives wherein the cost is reduced so as to make it possible economically to package items in this manner including items Which are not of a character to warrent expensive packaging.
A further aim is to provide such a package and method wherein the package has improved physical properties and characteristics such as increased toughness and a lesser tendency to tear or rupture or to delamimate, and a desired transparency or clearness of the covering sheath. Included in this aim is the provision of a package and method wherein a relatively close formfitting sheathing of the article may be attained even with articles of larger size or of irregular configuration Which could not be satisfactorily mechandized in this general type of package heretofore.
Another aim is to provide a method which can be practiced without complex machinery or operating skills and which can attain high volume production of uniformly good quality with a minimum of rejects and down time.
Other objects will be in part obvious, and in part pointed out more in detail hereinafter.
The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.
In the accompanying drawings:
FIG. 1 is a perspective View of an exemplary package formed in accordance with the present invention, the package being severed from a plurality of packages formed simultaneously therewith as indicated by dotted line;
FIG. 2 is a transverse cross-sectional view of the package shown in FIG. 1; and
FIG. 3 is a schematic showing of-apparatus for performing the method of the present invention in the initial position thereof; and
FIGS. 4-6 are schematic showings of the essential por- 3,631,072 Patented Apr. 24, 1962 tion of the apparatus in FIG. 3 during various subsequent steps of the method.
It has now been found that the foregoing and related objects may be attained by a method in which the article to be packaged is placed on a paperboard base or substrate, a sheet of transparent thermoplastic film is heated sufficiently to render the film deformable and to activate at least the contacting surface thereof for heat-sealing to the base, and the film and base are brought into a position with the activated surface of the film closely overlying the article and base while drawing suction through the base. The heated film deforms and shapes itself about the article to be packaged and the artivated surface of the film bonds itself to the surface of the paperboard base by its own substance throughout the area surrounding the article.
Referring to FIGS. 1 and 2 of the drawings, therein illustrated is an exemplary composite package formed in accordance with the present invention. The package is comprised of a paperboard base or substrate 10 upon which is placed the article to be packaged, the illustrated part being a small cylindrical part 12. Overlying the article 12 and the paperboard base or substrate 10 and coextensive with the latter is a transparent covering web or sheath 14 formed of thermoplastic film. The thermoplastic film is drawn closely about the article 12 so as to hold the article tightly on the paperboard base. It does not, however, adhere to the surface of the article 12. The remaining portion of the thermoplastic film 14 is in intimate laminar contact with the upper surface of the paperboard base it} and is adhered or bonded thereto by its own substance. The lines 16 are score lines in the upper surface of the paperboard substrate which are desirably present in the preferred embodiment of the invention.
The paperboard base or substrate 16 is formed of a porous paperboard stock which is of sufficient rigidity for the packaging application and which will permit the drawing of a vacuum therethrough. The paperboard stock utilized for the present invention is free from any coating of adhesive or thermoplastic material, and is preferably only lightly calendered so as to preserve its inherently porous, gas-permeable nature. A suitable paperboard stock, for example, is the type known in the trade as patent coated which has a face or top layer composed essentially of virgin pulp and high grade Waste free of ground wood and presenting an attractive finish and appearance. In the event a' colored background or base color is to be used, which is frequently the case, it is preferred to select a paperboard Which has been vatdyed with the desired color during its manufacture. This is found to be an advantage because it eliminates the need to print that color on the paperboard.
As illustrated in the drawings and as described herein, the paperboard base or substrate it i not perforated for the present invention and the vacuum is drawn through the pores of the paperboard substantially uniformly throughout the area of laminar contact. The termsubstantially imperforate as used herein refers to such an essentially imperforate paperboard substrate but does not exclude incidental perforations such as those known in the art for the purpose of hanging the package.
When the paperboard is printed, care has to be taken to select an ink which will not interfere with the bonding process, since certain inks contain'sufficiently high quantities of binder to interfere with the porosity of the paperboard stock or otherwise interfere with the bonding operation. Exemplary of those inks found suitable for the present invention are Black BL9061 and Vaposet Black 58 NH-17l0, products of Interchemical Corporation.
The covering Web or sheath 14 is formed of thermoplastic film or sheet material which can be deformed readily when subjected to heat and air pressure and which can be bonded to the paperboard base or substrate by its own substance without the use of adhesives or bonding agents. To provide a suitable package, the thermoplastic film must be one which is transparent, tough and durable and One which is substantially free from webbing in the final package.
It has been found that certain polyolefin film can be heated to render them deformable and heat-sealable by their own substance to the paperboard substrate, without the use of adhesives, while maintaining substantially the integrity of the body of the film. Generally, these suitable films are characterized by having at least their contacting surface more susceptible to activation by heat than the body of the film for scaling to the paperboard. Although the phenomenon is not fully understood, this susceptibility to heat-activation is generally considered to be the result of oxidation of the molecules and/or of reduction of molecular weight. so that the surface of the material is more responsive to heat than the body of the film. Surface treatments commonly employed to render polyolefin film susceptible to ink printing have proven effective for the present invention, and among those treatments generally known are electrical discharge and irradiation. However, the surface oxidation occuring during certain processes of extrusion of the film onto the chill member will provide a surface of the desired nature, although not as highly susceptible to activation by heat as one which is further surface-treated by electrical discharge or like methods.
The term surface-treated polyolefin film, as used hereinafter, refers to polyolefin films having one or both surfaces at least partially oxidized or surface-treated to render the surface more susceptible to activation by heat than the body of the film.
Generally, the polyolefin films utilized in the present invention should be substantially unoriented to prevent shrinkage and stress, and should contain no appreciable quantities of additives which will migrate to the contacting surface of the film and interfere with the bonding operation by vaporization or otherwise. Among those additives which have been found to be detrimental are secondary plasticizers, slip additives, and appreciable quantities of primary plasticizers.
The polyolefin films utilized in the present invention have a thickness of about 3 to 11 mils, and p eferably about 4 to 7 mils depending upon the degree of distention required to form a sheath about the article.
Although polyethylene films have proven most advantageous in the practice of the present invention, polypropylene films may be utilized albeit their somewhat brittle nature and tendency to shrink render the commercial operation more critical. The preferred films are extruded and unoriented, low to medium density surfacetreated polyethylene films. Specific examples of the preferred films are those designated by the Shellmar-Betner Division of Continental Can Company, Mt. Vernon, Ohio, as 3324-4969 and by Ludlow Papers, Inc., Needham Heights, Massachusetts, as A-52. Although both of these films are electrostatically treated on only one side, the reverse surface is also partially oxidized during the process of extrusion, and this is particularly pronounced in the case of the Continental Can film.
Referring to the attached drawings, the method of the present invention may be more clearly understood by the schematic views of exemplary automatic or semiautomatic equipment during various stages of the operating cycle.
In the initial step, the articles to be packaged 12 are assembled on a paper board substrate 10 hearing a series of printed designs and adapted to be sub-divided into individual cards. The substrate is preferably provided with parallel score lines as at 16 in FIG. 1. These score lines are not essential but enhance the appearance since they provide an interesting background and tend to overcome the tendency of the package to curl as the result of any shrinkage of the film. Additionally, the score lines may possibly assist in promoting bonding of the film. This assembly of substrate and articles is placed on flanged metal trays 2%) having perforated bottoms which are so constructed as to enable drawing of a vacuum from the underside. The trays 20 carrying the assembled parts are advanced from the initial assembling station by means of a suitable transfer table 22 and are then transferred to the platform 24 of elevator 26. As shown in the drawings, a suction line 28 and an air line 30 are connected to the platform 24- and may be used to draw a vacuum or blow air through a paperboard substrate seated in the perforated metal tray 20.
Polyolefin film from the rotatably mounted roll 32 extends over a lower clamping frame 34 which is adapted to receive the platform 24. Upper clamping frame 36 is movable into engagement with lower clamping frame 34 to retain the polyolefin film therebetween in taut relationship. The major operating assembly is completed by a heater 38, conveniently comprised of a series of resistance coils or Calrod units, which i extensible into position overlying the clamping frame 36, and a cooling fan 40.
in the next step, illustrated by FIG. 4, the upper clamping frame 36 is moved into engagement and the heater 38 is operatively disposed above the upper clamping frame 36 a predetermined distance from the polyolefin film 28. The heater 34 generates sufficient heat to render the polyolefin film deformable by air pressure and to activate at least the lower or contacting surface thereof for heat-sealing to the paperboard substrate.
A Calrod unit capable of developing 1200" F. spaced about 8 inches from the film has proven quite satisfactory with heating cycles of about 2-12 seconds depending upon the thickness of the film. The exact length for the heating cycle is best determined by trial although visual observation of the distention of the film under its own weight will be an indication of the proper heating period. Overheating of the film is undesirable since it tends to destroy the film, cause clouding, and otherwise interfere with the satisfactory practice of the invention. Additional factors of importance in connection with the heating step will hereinafter be described.
In the next step, illustrated by FIG. 5, the platform 24 hearing the tray 20 is moved up into the frame 34 and into proximity with the heat-activated surface of the now deformable polyolefin film while suction is applied to the underside of the paperboard substrate. The suction deforms and draws the film into close skin-like contact on the parts 12 and into laminar contact with the upper surface of the paperboard substrate 10 over substantially the entire area surrounding the parts. The heat-activated surface of the polyolefin film is drawn by the suction into the pores of the paperboard substrate to form a laminated structure having a strong bond formed by the substance of the polyolefin film itself. The film deforms and shapes itself into close-fitting relationship with the articles but is not appreciably adherent thereto.
The suction applied to the bottom of the paperboard should be sufficient to distend the film over the articles and to draw the surface of the film into the pores of the paperboard. in a commercial embodiment, suction rated at 23 inches of mercury (about 11.5 pounds per square inch) has proven highly satisfactory. This will, of course, vary with the permeability of the paperboard and the conditions of operation. Generally, the suction is applied for about 2 to 20 seconds to bring the film and paper board into laminar bond, 3 to 5 seconds being satisfactory for most operations.
Although not essential to the satisfactory practice of the invention, it is often desirable to cool the package by the fan 4t) after withdrawal of the heater 3%. The circulation of cooling air tends to facilitate the set of the bond formed between the film and the board.
Finally, as indicated in FIG. '6, the upper frame 36 is removed from lower frame 34 and the elevator 26 is lowered to withdraw the platform 24 and tray 20 from the lower frame 34. Most conveniently, a blast of air through line 30 assists in disengaging the paperboard substrate from the tray 20. The polyolefin film is drawn outwardly to remove the packaged assembly from the apparatus, and the assembly is then severed from the film and cut or otherwise separated into individual packages.
The film should be initially distended away from the article and paperboard so that it will be drawn down into contact by the applied suction rather than sag into contact. This mode of operation substantially eliminates webbing and wrinkling. In operation with films of 3 to 6 mils thickness, an excessive amount of air tends to be entrapped between the paperboard and film which may overly expand and blow out the film. In dealing with films of this thickness, it is generally necessary to begin drawing the suction through the paperboard prior to bringing it into sealed engagement with the clamping frame so as to quickly reduce the entrapped air volume.
When employing polyolefin films of 6 to 11 mils thickness on articles of low height, the air normally entrapped therebetween will oftentimes be sufficient, but, in other instances, when the film tends to sag into contact with the articles prematurely, additional air is most desirably supplied to ensure distention of the film away from the paperboard, conveniently by supplying air under pressure through the air line 30 and thence through the gas-permeable paperboard.
Also, in using films of 3 to 6 mils thickness, heating the film sufiiciently to cause the film to sag and then grow taut again, a point which is called the shrink-temperature has proven most advantageous. Preferably, the bond is formed as closely in time to this point as possible to provide a package of superior clarity with substantially no cloudiness and ripples.
Exemplary of the present invention are the following examples wherein packages were made in apparatus of the type schematically illustrated in the attached drawings. In each of the examples, the parts packaged were metal chest handles of about 1% inches in height.
Example One A quantity of chest handles were arranged on a vatdyed patent coated paperboard substrate of about 0.032 inch thickness. Low-density, unoriented extruded polyethylene film of about 6 mils thickness (Ludlow A52) which had been surface treated on the contacting side, was heated by the Calrod heater for about 8 seconds, the heater being spaced about 8 inches from the film and developing a temperature of about 1050 F.
Immediately prior to the end of the heating period, the elevator platform was raised to bring the substrate and handles into contact with the film, suction being applied to the underside of the substrate as it entered into the clamping frame. The suction is rated at 23 inches of mercury (about 11.5 pounds per square inch) and was drawn for about 3 seconds-after contact. The heater was withdrawn and the cooling fan was operated for about 3 seconds, after which the elevator and clamping frame were disengaged and the bonded assembly withdrawn.
The film was found to be tightly drawn over the handles and strongly bonded to the paperboard substrate throughout the area surrounding the handles. The film was substantially clear and evidenced no webbing. Attempts to delaminate the assembly resulted in removal of the top surface of the paperboard with the film.
Example Two The operation of Example One was repeated utilizing an extruded, low-density unorientedpolyethylene film of 4 mils thickness having one side surface treated by electrical discharge (Continental Can-designated 3324- 1969). The treated side was placed down (in contacting position) and the film was heated for about 5 seconds during which period the film sagged and grew'taut again.
Immediately prior to the end of the heating period and shortly after the film became taut again, the substrate and handles were brought into contact with the film, the suction having been drawn on the bottom of the substrate prior to contact with the film and maintained for about 3 seconds thereafter.
Upon removal of the package from the equipment, the film was found to be clear and free from webbing, closely shaped to the handles and very strongly bonded to the substrate over the entire area surrounding the articles. Attempts to delaminate resulted in removal of the top surface of the paperboard substrate with the film.
Example Three The process of Example Two was repeated utilizing the same film but with the electrostatically-treated side up. The manufacturer describes this film as oxidized upon both sides during the process of extrusion. Utilizing the same conditions of operation, a package was formed.
Upon removal from the apparatus, the film was found to be clear and free from webbing, drawn closely over the handles and bonded to the substrate over the surface area of the substrate surrounding the handles. The strength of the film-substrate bond was found to be satisfactory for commercial use, although it was not as strong as that formed by the treated surface.
From the foreging examples and specifications, it can be seen that the packages of the present invention are relatively inexpensive to produce and durable. These packages are consistently attractive in appearance and sufiiciently rugged to resist rupture or tearing under extreme conditions of use. The method of the present invention lends itself to rapid and highly efiicient automatic and semi-automatic operation with consistent highquality results.
I claim: I
l. A composite package comprising a substantially imperforate, porous paperboard base sheet, an article of merchandise disposed on the upper surface of said base sheet, and a covering of surface-treated polyolefin film overlying said article and base sheet, said film forming a non-adherent sheath closely conforming to the periphery of said article and being in laminar contact with the surface area of said base sheet from adjacent the periphery of said article to the margins of said base sheet, said film having its lower side surface-treated and being bonded by its own substance to said base sheet with a portion thereof extending into the pores of the base sheet throughout said surface area to form a paper-tearing bond.
2. The package in accordance with claim 1 wherein said polyolefin film is a polyethylene film of about 3-11 mils in thickness.
3. A method of forming a composite package containing a sealed article of merchandise comprising the steps of placing an article on the topside of a substantially imperorate, porous paperboard base sheet; supporting at opposed margins a sheet of surface-treated polyolefin film above said base sheet and article, said film having been surface-treated on its lower side adjacent said paperboard base sheet; heating said polyolefin film to render the film deformable and to activate the treated surface for heatsealing to the base sheet while maintaining substantially the integrity of the body of the film; and immediately thereafter applying suction to the underside of the base sheet while supporting the heated polyolefin film in a position above and closely overlying the base sheet and article to draw the polyolefin film downwardly about the article into a sheath closely conforming to the periphery of said article and into laminar contact with the surface area of said base sheet from adjacent the periphery of said article to the margins of said base sheet and to bond said film immediately upon laminar contact by its own substance to the base sheet with portions of the film extending into the pores of the base sheet throughout said surface area to form a paper-tearing bond.
4. The method in accordance with claim 3 wherein said polyolefin film is polyethylene film of about 3-11 Kids in thickness.
References Cited in the file of this patent UNITED STATES PATENTS 8 Groth .Oct. 14, 1958 Hartford Nov. 25, 1958 Maynard Mar. 10, 1959 McCurry Mar. 21, 1961 FOREIGN PATENTS France Dec. 5, 1955 Great Britain July 11, 1956 Great Britain Nov. 7, 1956 Great Britain Oct. 9, 1957 OTHER REFERENCES A New Material; Irradiated Polyethylene-Chemical Enginecring Irradiation, September 1955, pages 228-234.