US2668403A

US2668403A - Method of making heat-sealed and heat-shrunk package

Info

Publication number: US2668403A
Application number: US211530A
Authority: US
Inventors: Jr Herbert Rumsey
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-02-17
Filing date: 1951-02-17
Publication date: 1954-02-09
Anticipated expiration: 1971-02-09

Description

Feb- 9, 1954 H. RUMsEY, JR 2,668,403

METHOD OF MAKING HEAT-SEALED AND HEAT-SHRUNK PACKAGE Filed Feb. 17, 1951 I5 Sheets-Sheet l 3 INVENTOR. v 28 lf2 'hij 21a/15x95 BY .Y

r KAL Feb. 9, 1954 H. RuMsEY. .1R 2,668,403

METHOD OF MAKING HEAT-SEALED AND HEAT-,SHRUNK PACKAGE 3 Sheets-Sheet 2 Filed Feb. 17. 1951 im ZKM /7 TTU/EWEY Feb. 9, 1954 H. RuMsEY, JR 2,668,403

METHOD 0F' MAKING HEAT-*SEALED AND HEAT-SHRUNK PACKAGE '5 Sheets-Sheet 3 Filed Feb. 17. 1951 41 INVENToR f6 isf/Zeri Fur/15e /ff MM f @L Patented F eb. 9, 1954 METHOD OF MAKING HEAT-SEALED HEAT-SHRUNK PACKAGE AND Herbert Rumsey, Jr., Rochester, N. Y. Application February 17, 1951, Serial No. 211,530

This invention relates to an improved heat sealed package and. to a method of making the same.

My invention has particular relation to a package encased in thermoplastic sheet material and it isan object of the invention to provide an improved package and method of this type wherein the thermoplastic sheet material is wrapped and secured around the package in an improved tightly wrapped manner so as to present an attractive appearance substantially free from wrinkles and irregularities.

My invention contemplates an improved package having a relatively stii support for protecting the package contents and providing the desired contour and shape tothe package and a wrapping of exible sheet materialwhich may be applied relatively loosely but is then shrunk around the package so asto complete the assembly of the package andy then retain it in properly assembled relationship. The wrapping also presents a smooth finished appearance to the package.

My improved method and package are relatively inexpensive, do not require highly skilled or trained employees and result in an improved attractive package in which the contents are effectively protected.

In the accompanying drawing- 4 Fig. 1 is a perspective View illustrating the I'lrst step in carrying out my improved process;

Fig. 2 is a similar View of a further step; I

Fig. 3 is a perspective View showing the manner in which the package may be placed on heat sealing apparatus for the heat sealing step;

Fig. 4 is a side elevational view illustrating the step of heat sealing;

Fig. 5 is a detailed view showing the engagement between the package being wrapped and one of the heat sealing prongs of the apparatus shown -in Figs. 3 and 4;

Fig. 6 is a similar detailed view showing the manner in which the thermoplastic wrapping material of the package is heat sealed or fused;

Fig. 7 is a perspective view of a partially wrapped package which has been heat sealed along one edge;

Fig. 8 is a similar view in which another edge of the wrapping material has Ibeen folded over and heat sealed;

' Fig. 9 is a similar view in'which the final edge has been folded over and heat sealed;

Fig. 10 is a perspective View illustrating the step in my process wherein the thermoplastic Wrapping material is heat shrunk around the Package; Y f- .55. I8 is not essential and may beeliminated.

3 Claims. (Cl. 5310.5)

Fig. 11 is a view of the completed package with the thermoplastic wrapping material shrunk therearound so as to present a smooth, unwrinked appearance. s j

Fig. 12 is a. plan View of a blank for a supporting member which may be used in a modiiied form of package;

Fig. 13 is a perspective View of the supporting member after it has been folded around the package contents; l'

Fig. 14 is a perspective View similar to Fig. 13 illustrating the manner in which a sheet of thermoplastic wrapping material may be wrapped thcrearound;

Fig. 15 is a perspective view'from the underside of the package with the thermoplastic wrapping material heat sealed around the package but prior to the shrinking of the lwrapping material;

Fig. 16. is a longitudinal sectional View in v'the direction of the arrows on line Iii- I6 of Fig. 15 ;V

Fig. 1'7 is a cross-sectional View in the direc*- tion of the arrowson the line l'l-l'l of Fig. 15

Fig. 18 is a perspective view of the completed package with the thermoplastic sheet material tightly shrunk around thepackage so as tocomplete the assembly and retain it in position; and Fig. 19 is a cross-sectional View in the direction of the arrows onV the line lil- I9 of Fig. 18. n d My invention is applicable to packages wrapped in thermoplastic sheet material and may be used in connection with packages of Varying types and shapes. However, it has particular application to relatively ilat packages and to packages having a relatively stiff supporting member or base and a flexible wrapping which is tightened around the package to complete the assembly and retain it in assembled relationship and also to present a neat, nished appearance. Y In the accompanying drawings I have illustrated my invention as applied to at packages of this type having a supporting member or base. Thus, in Figs. 1 to 11, I have illustrated a package l5 of shingled bacon disposed in a support in the form of a relatively stiff member or base i6 made of cardboard or other suitable material. The iiat base portion extends Vacross the bottom of the package and three integral flaps l1 extend upwardly and overlap theV face along three marginal edges. The outer surfaceof the support may have a coating I8 of thermoplastic material such as wax, parain, thermoplastic resin orthe like having a lower melting or fusingv point than the sheet wrapping material. How'- ever, it should be understood that `the coating In accordance with my method the support and its contents are wrapped in the manner hereinafter described in a sheet I9 cf thermoplastic wrapping material. The thermoplastic sheet inaterial may be of any known type such as cellulose acetate, or other cellulose esters, Pliolm or preferably a thermoplastic sheet material of the type which shrinks when heat is applied thereto such as a polyvinyl film, specifically polyvinylidene chloride of the type available commercially under the trade name of Saran. l

The rst step of my method may be carried out on a suitable station such as platform 20. The package contents and support are placed face downwardly on the sheet I9 of thermoplastic wrapping material on top of platform 2E and a relatively narrow strip of the wrapping material is folded over the back of the package on the supporting member along one marginal edge as shown at 2l. Thereafter, the sheet of thermoplastic wrapping material is drawn upwardly cn thev platform 20 and the entire package is folded over upon itself in the mannerl illustrated in Fig. 2.

It Will thus be seen that the thermoplastic wrapping material has been wrapped around the package forming a tube ofY wrapping material open at both ends of the package and with the wrapping material arranged in overlapping relationship along one marginal area at the back of the package as shown at 2 I.

The next step in my method is to heat seal the overlapping marginal edges of the Wrapping material together and to sever the sheet wrapping material along an edge of the package from the supply source. The heat sealing should preferably take the form of a plurality of proximately positioned heat sealed or fused points or spots extending along the overlapping marginal areas inthe manner taught in my patent application Serial No. 37,978, filed July l0, 1948, for Package Encased in Plastic Material and Method of Making the Same, now Patent No. 2,545,243, granted October l0, 1950. v

VI prefer to accomplish the heat sealing and the severing of the web of wrapping material from the source of supply by-means of a single operation in the manner taught in my copending application Serial No. 198,107, lcd on November 29, 1950, for Apparatus for Heat Sealing and Severing Thermoplastic Materials,A now Patent No. 2,635,672, granted April 2l, 1953. Thus, as shown in Figs. 3, 4, and 5 the package l5 is transferred to another station taking the ferm of a hinged platform 22 pivotally mounted at 23 and normally held in elevated or horizontal position by means of a helical spring 24. The package is placed upon the platform in upright position with the reinforcing backing i6 facing downwardly and with the overlapping margins 2l positioned above apertures 25 formed in the platform. Beneath the respective apertures 25 are a` plurality of heat sealing prongs 26 made of copper or other suitable material and arranged in a row in alignment with the apertures. The prongs are suitably heated as by means of an electric heating element. When the left-hand end of the platform, as viewed in the drawings, is depressed the prongs enter through the apertures 25 and engage the overlapping marginal portion of the Wrapping material. The heat of the prongs is preferably controlled so that when they engage the thermoplastic Wrapping material they` cause the overlapping layers of the material to fuse at the points of contact thereby forming a plurality of apertures 2l through the layersv of material` as shown in Figs. 5 and 6. When the force is removed from the platform the spring 24 returns it to horizontal position thereby withdrawing the engagement of the prongs from the wrapping material. The result is that the fused thermoplastic material sets Vor hardens sealing the layers of wrapping material together around the apertures as shown in Fig` 6.

The overlapping layers of material will thus be heat sealed or fused together at a plurality of proximately positioned points throughout the marginal area. ff desired, the temperature of the prongs 26 may be maintained at a level where they will not form apertures completely through the` thermoplastic sheet material but will only cause spot adhesions similar to spot welding. The control of the temperature may be accomplished by thermostatic means or by reducing the diameter of the prongs or by making them of a material which is a less efficient conductor such` as ferrous metal rather than copper.

The prongs 26 are suitably supported so that they rest upon the copper plate 28 and heat from the plate will readily transfer to the prongs. The plate 28 has an upstanding flange 29 at the edge thereof forming a heat severing blade. The blade 2Q is maintained at a temperature whereby it will fuse the thermoplastic material so that it can be readily heat severed from the source of supply. The blade 2) is arranged so that normally it is cut of contact with the web of wrapping material as shown in Fig. 3. Thus, platform 22 has an upturned flange or edge 3G serving as a stop for positioning the package. The upper edge of the stop or flange 30 is positioned substantially above the upper edge of the blade 29 when platform 22 is in elevated position. However, when the platform is depressed as shown in Figs. 4 and 5 the upper edge of flange 3G is positioned beneath the upper edge of the heat severing blade with the result that the heat severing blade engages the web of thermoplastic wrapping material and causes it to` be severed from its source of supply. Thus, in one operation the wrapping material is severed along one edge of the package from its source of supply and the wrapping material is spot welded or fused together in the marginal overlapping area.

At this stage in my method the package is encased in a tube of thermoplastic wrapping material as shown in Fig. 7 with the ends of the Wrapping material in open condition and with the wrapping material having an overlapping marginal area on the undersurface thereof. The layers of wrapping material in the overlapping area are spot welded or fused together at a. plurality of proximately positioned points.

In the illustrated embodiment the sheet Wrapping material is of such a Width thatthe open ends project beyond the two sides of the package, as indicated at 3l and 32. When the Wrapping material is thus wider than the package the respective ends are folded inwardly against the undersurface of the package and heat sealed together in the same manner as the overlapping marginal band portion. Thus, as shown in Fig. 8, the end portion 3| is first turned under and the package is placed upon the platform 22 with the inturned end 3l disposed upon the apertures 25. The platform is then depressed so that the heated prongs 26 engage the overlapped ends of the material forming aI plurality of apertures 21 which are heat sealed or fused around their marginal edges. The end 32 is then turned inwardly against the undersurface of the package and the-package is again positioned-on the platform 22 with the inturned ends 32 resting over the apertures 25 and the operation-is again repeated. In this connection, it should be noted that the prongs 26 can penetrate any desired number of layers of the thermoplastic sheet material and in the marginal areas 3l and 32 a plurality of layers of the material are penetrated and fused together.

When all of the marginal areas have thus been heat fused or sealed together as shown in Fig. 9, it will be seen that the package is encased in the thermoplastic wrapping. However, as indicated the thermoplastic wrapping vmaterial is not stretched tightly around the package and is wrinkled rather than smooth.' vWhere the sheet wrapping material is of a character which can be shrunk as, for instance, polyvinylidene chloride which can be heat shrunk, I then shrink the wrapping material around the package to provide a smooth, taut surface presenting an attractive appearance free from wrinkles. The shrinking also serves to press the supporting member tightly against the package contents and to hold the package in properly assembled relationship.

This may be accomplished in the manner indicated in Fig. by means of a heated plate The plate 33 is heated to a temperature which will cause shrinkage of the thermoplastic wrapping material but will not fuse or melt the material. However, where the supporting member I6 has a coating I8 of wax or thermoplastic resin, the temperature of the plate should be such that it Will cause fusing or melting of the wax or similar coating.

In shrinking the material around the package I first piace the package face downwardly on the plate 33 so that as the wrapping material contracts, the air inside the package can escape through the apertures 2l. Thereafter, the back of the package is pressed downwardly on the hot plate 33 in the manner shown in Fig. 10 causing the shrinking of the wrapping material in that area and simultaneously melting or fusing the wax or other coating i8, where such a coating is employed. The melting of the wax coating andits subsequent setting causes an adhesion, sealing cr fusing together of the wrapping material and the supporting member of the package with the result that the contents of the package are effectively protected from undue exposure to the atmosphere.

The nished package as shown in Fig. 1 presents an attractive appearance with the thermoplastic wrapping material tightly stretched in smooth relationship around the package so as to retain it in properly assembled relationship and so as to be substantially free from wrinkles. The apertures 2i present spot fused or sealed spots in proximately positioned relationship along the overlapping marginal portions of the wrapping material. The adhesion between the waxed surface of the supporting member l 6 and the wrapping material prevents undue exposure of the contents of the package to the atmosphere.

It should be noted that by making the package in the manner herein illustrated and described a flap 34 is provided along the edge of the package immediately adjacent the overlapped margin 2l and parallel to the side of the package. This ap forms a convenient tab that can be grasped in the hand and pulled for the purpose of opening the package. Also, due to the fact that the ap extends upwardly away from the overlapped opened due to frictional engagement with protruding members.

In the modified package shown in Figs. 12 to 19 the Wrapping material is in the form of a tube wrapped around the package and open at both ends` It will be seen that I have provided a relatively stiff supporting member 35 which serves to protect the package contents and to retain the package in relatively flatform. No coating need be applied to the supporting memberk but may be if desired. The supporting member may extend over one surface only of the package or as shown may extend completelyv around the package contents. Thus, I have il-V lustrated the supporting member as having a base portion 35 with side naps 3l, a top portion 38 and an overlapping flap 39 for overlapping the bottom of the package. The top portion 38 may be provided with a suitable window opening 40 through which the package contents are displayed.

The supporting member may be provided in blank form as shown in Fig. 12. The rst step in my method is to place the package contents upon the upper surface of the base portion 36 and to wrap the supporting member around the contents in the manner shown in Fig. 13 so that the flaps 31 are folded inwardly over the ends of the package contents, the top portion 38 extends over the upper surface of the contents and the flap 3Q is folded beneath the base portion 3S. Because the supporting member is relatively stiff, it resists the folding action and the various panels and flaps ID tend to bulge outwardly as shown in Fig. 13.

Thereafter a sheet 42 of thermoplastic wrapping material of the type which can be shrunk around the package such as a polyvinyl nlm, par-` ticularly polyvinylidene chloride, is wrapped around the outside of the supporting member in ie manner indicated in Figs. 14 and 15. The sheet 42 should preferably be of a size to extend Y for substantially the length of the package as l shown and so as to extend completely around the package in tubular form with its ends in overlapping relationship.

The overlapping edges of the wrapping material are vpreferably positioned on the undersurface of the pack-age as shown in Figs. 15 to 19 adjacent flap 39. These edges are heat sealed in the manner previously described in connection with the first form of my invention so as to form aplurality of spots or apertures 43 extending through both layers of the thermoplastic material with the peripheral edges fused or sealed together.

As shown in Figs. l5, 16 and 17, after the sheet of wrapping material has thus been wrapped around the package and heat fused or sealed in position it lits rather loosely and the flaps and panels of the supporting member, because of the stiiness thereof, continue to bulge outwardly. Under those circumstances, the package does not present a finished appearance and the assembly of the supporting member around the package contents is not complete.

In order to complete the assembly of the package and present a finished, attractive appearance, I thereafter heat shrink the wrapping material 42 around the package in the manner described in connection with the first form of my invention. This may be accomplished by pressing the upper and lower surfaces of the package against a hot plate of the type shown in Fig. 10.

The shrinking of the wrapping material around the package pulls the flaps and panels tightly into proper position and also eliminates the wrinkles and surplus material from the wrapping material as shown in Figs. 18 and 19. The nished package, as shown in Figs. 18 and 19, is held in proper, assembled relationship by means or" the wrapping material and presents a neat, attractive and nnished appearance.

It will thus be seen that I have provided an improved heat sealed package and method of making the same wherein a package of attractive appearance affording protection to the contents thereof can he made in a relatively simple and lnexpensive manner. Modications may be made in the illustrated and described embodiment of my invention without departing from the invention as set forth in the accompanying claims.

I claim:

l. The method of making a package which comprises: placing package contents on a relatively stii supporting member having a coating of thermoplastic material on the outer surface thereof; wrapping thermoplastic sheet material of the type which shrinks when subjected to heat and which has a higher melting point than the thermoplastic coating, around the package contents and support with marginal areas of the sheet material arranged in overlapping relationship in contact with the support; heat sealing the overlapping marginal areas of the sheet material together; and subjecting the wrapped package to a temperature lower than the melting point of the sheet material but higher than the melting point of the thermoplastic coating so as to shrink the sheet material tightly around the package and so as to seal the wrapping material to the support.

2. The method of making a package which comprises: placing package contents in relatively iiat form on a flat stiff supporting memberl having a thermoplastic coating on the outer surface thereof; then wrapping thermoplastic sheet material of the type which shrinks when subjected to heat and which has a higher melting point than the thermoplastic coating, around the package contents and support with marginal areas in overlapping relationship in Contact with the support; next securing the marginal areas together by subjecting the sheet material to heat higher than the melting point thereof at a plurality cf spaced points so as to form spaced apertures extending through the overlapping layers of the sheet material with the edges of the material around the apertures fused together; and nally subjecting the wrapped package to a temperature lower than the melting point of the sheet material but higher than the melting point of the thermoplastic coating so as to shrink the sheet material tightly around the package and seal the sheet material to the support.

3. The method of making a package which comprises: placing package contents on a relatively stiff supporting member having a coating of thermoplastic material on the outer surface thereof; Wrapping thermoplastic sheet material of the type which shrinks when subjected to heat and which has a higher melting point than the thermoplastic coating around the package contents and support with marginal areas of the sheet; material arranged in overlapping relationship in contact With the support; securing the marginal areas of the sheet material together by subjecting these areas of the sheet material to heat higher than the melting point thereof at a plurality of spaced points so as to form spaced apertures extending through the overlapping layers of sheet material with the edges of the material around the apertures fused together; subjecting the sheet material over the face of the package to an elevated temperature lower than the melting point thereof with the apertures in the marginal areas left unobstructed so as to shrink the sheet material over the face of the package and so that the air may escape through the apertures; and finally subjecting the sheet material over the supporting member to an elevated temperature lower than the melting point thereof but higher than the melting point of the thermoplastic coating so as to shrink the sheet material tightly over the supporting member and seal the sheet material thereto.

HERBERT RUMSEY, JR.

References Cited in the ille of this patent UNITED STATES PATENTS Number Name Date 1,923,452 Neumillel Aug. 22, 1923 2,008,167 Bergstein July 16, 1935 2,029,131 Shoemaker Jan. 28, 1936 2,131,699 ONeill et al. Sept. 27, 1938 2,149,030 Moore Feb. 28, 1939 2,168,651 McCoy Aug. 8, 1939 2,179,504 Hasbrook Nov. 14, 1939 2,301,086 Snyder Nov. 3, 1942 2,331,794 Mallory Oct. 12, 1943 2,518,711 Mulford Aug. l5, 1950 2,545,243 Rumsey Mar. 13, 1951