US3636678A

US3636678A - Packaging method and package made thereby

Info

Publication number: US3636678A
Application number: US17694A
Authority: US
Inventors: Frank George Maros; Jeffrey Scott May; Harold Eugene Ramsey
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1970-03-09
Filing date: 1970-03-09
Publication date: 1972-01-25
Anticipated expiration: 1989-01-25
Also published as: CA952811A

Abstract

A method of packaging an article between at least two moving package members, such as plastic film in web form, including drawing one member into skinlike engagement with the article and into sealing contact with the other member by means of a suction means positioned between the members. The method is continuous in operation and one of the package members may be electrostatically treated prior to drawing. A third package member is positioned between the suction means and the package member drawn into engagement with the article and the other package member thereby to shield the suction means from the drawn member during the drawing operation. The third package member also may serve as a tear strip in the package formed by this method.

Description

United States Patent Mares et al 51 Jan. 25, 1972 PACKAGING METHOD AND PACKAGE MADE THEREIBY Inventors: Frank George Maros, Media; Jeffrey Scott May, Claymont; Harold Eugene Ramsey, Wilmington, all of Del.

E. I. du Pont de Nemours and Company, Wilmington, Del.

Filed: Mar. 9, 1970 Appl. No.: 17,694

Assignee:

U.S.Cl ..53/l4,53/22 A,53/l 12A ...B65b 61/18, B65b 31/04 ..53/22 A, 112 A, 14

References Cited UNITED STATES PATENTS Dallas Anderson Young et al. Morse ..53/22 FOREIGN PATENTS OR APPLICATIONS 795,397 5/1958 Great Britain .53/22 Primary ExaminerTravis S. McGehee AttarneyHoge T. Sutherland [5 7 ABSTRACT A method of packaging an article between at least two moving package members, such as plastic film in web form, including drawing one member into skinlike engagement with the article and into sealing contact with the other member by means ofa suction means positioned between the members.

The method is continuous in operation and one of the package members may be electrostatically treated prior to drawing. A third package member is positioned between the suction means and the package member drawn into engagement with the article and the other package member thereby to shield the suction means from the drawn member during the drawing operation. The third package member also may serve as a tear strip in the package formed by this method.

7 Claims, 4 Drawing Figures PMENIEm-zsme 3636x578 iLJV/%/%L L N INVENTOR NK AROS FRE MAY HAROLD E. RAMSEY ATTORNEY PACKAGING METHOD AND PACKAGE MADE THEREBY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is a package-making method and, more particularly, is directed to a novel method of continuously skinpackaging an article or a plurality of articles in plastic film.

More specifically, the invention relates to a method of packaging an article, such as a piece of meat, in plastic film to form a skin package including the steps of drawing a moving plastic web into skinlike engagement with the article being packaged and into sealing engagement with another moving plastic web carrying the article by means of a suction means located between the webs.

2. Description of the Prior Art Packaging methods of this general type are old. It is known, for example, to skin package an article by drawing a top web into engagement with an article and a bottom web by sucking air through perforations or other means providing air passages in the bottom web.

US. Pat. No. 1,856,694 to De Correvont, which is exemplary of the prior art, discloses an apparatus for covering articles including a movable support for a core and means for providing a condition of lesser pressure on the supported side of a heated sheet to draw the sheet around the core.

U.S. Pat. No. 2,690,593 to Abercrombie discloses moving a heater housing and platen towards a base to envelop an article positioned thereon in a plastic sheet, followed by subjecting the surface of the plastic sheet to reduced pressure to shrink it about the article.

US. Pat. No. 2,799,589 to Grinstead discloses placing a product within packaging material, the edges of which are clamped to produce a fiuidtight joint, after which a greater pressure is applied to the outer surface of the material than that existing on the inner surface of the material.

US. Pat. No. 3,260,032 to Hill et al. discloses clamping means for film shrunk around an article by suction in a package-making apparatus.

US. Pat. No. 3,290,858 to Eberman et al. discloses a continuous package-forming machine in which vacuum means are provided for holding an upper film out of the way of an article to define an article-receiving pocket therefore, followed by shrinking the upper film about the article and into sealing contact with a lower film in a continuous operation.

U.S. Pat. No. 2,855,735 to Groth discloses a method of packaging articles consisting of applying or coating an adhesive only onto parts of a porous paper substrate and sucking air through the uncoated areas thereof (i.e., the areas where adhesive has not been applied, or has been removed) to draw a film into engagement with an article on the substrate and with the adhesive thereon to form a skin package.

These methods require that one of the packaging members be porous or air-permeable or that the packaging operation be noncontinuous, which imposes severe limitations upon packaging speeds or the type of package made using such methods.

SUMMARY OF THE INVENTION Briefly described, the method of packaging of this invention includes the steps of:

positioning an article to be packaged between a top web and a bottom web of plastic film, with at least parts of the article resting on the bottom web;

heating at least the top web to render it drapable;

moving the article and the top web relative to each other thereby to drape the heated film over the article;

withdrawing air from between the top and bottom webs by means of suction whereby the top web is drawn into skinlike engagement with the article and whereby the top and bottom webs are drawn into engagement with each other along at least the side edges thereof to seal these edges together and are drawn into engagement with each other along at least portions of the leading and trailing edges thereof to at least partially seal these edges together, the suction being applied by means of a suction means extending between the top and bottom webs and extending in the direction of movement of the webs and below the article whereby the article slides over the suction means as the article is carried by the bottom web;

removing the suction means from between those portions of the webs forming an individual package; and

sealing any unsealed portions of the leading and trailing edges of the top and bottom webs together after the suction means has cleared the trailing edge.

In skin packaging systems for packaging articles, such as meat, one of the major requirements is that the package-making apparatus or machine be capable of operating at relatively high speeds.

Obtaining such high speeds is a difficult mechanical task. This is particularly so if any of the packaging machine operations are other than substantially continuous. For this reason, it is highly desirable to avoid any drastic intermittent motions which would greatly decrease the high-speed capabilities of the machine or packaging method.

This invention provides a method of skin-packaging articles in a substantially continuous manner.

In known methods of skin-packaging articles, such as hardware items, a thermoplastic film is placed over an air-permeable base member on which the article to be packaged rests, is heated to a temperature at which it is readily formable, and is subjected to a partial vacuum by withdrawing air from between the thermoplastic film and the base member through the air-permeable base member. By the combination of such actions and package components, the thermoplastic film assumes a contour-conforming configuration with the article and is bonded to the air-permeable base member in all radial directions from the article. The base members are generally coated with an adhesive and are air-permeable either because they are perforated or because of the natural porosity of the material of the base member. Packages formed using these methods are not sealed from their ambient atmosphere. This greatly limits the types of products which can be so skin packaged. It is most desirable, for example, to seal meat products from their ambient atmosphere in order to extend their display life; therefore, such methods would have no utility in this packaging area.

Certain skin-packaging methods are known wherein impermeable packaging members are employed for overwrapping the article being packaged. Such packages are formed noncontinuously in vacuum chambers. A high vacuum is formed between the packaging members and around the article being packaged within the vacuum chamber. This vacuum is then maintained between the members while the two web members are bonded to each other.

This invention provides a method of and an apparatus for making hermetically sealed skin packages in a continuous manner using impermeable packaging members.

The package of this invention is formed in a continuous operation around a fixed evacuation no71le or suction means. A narrow porous web member having the articles to be packaged resting thereon is passed immediately above the fixed suction means while a top web member passes above the narrow web member and the articles located thereon. A bottom web member is passed below the articles and the suction means and the top web member and the bottom web member are brought together to form a transverse lineal contact while the space in the vicinity of the article immediately following the lineal contact of the top and bottom web members is evacuated causing the heated top web member to be urged against and sealed to the bottom web member'while simultaneously conforming to the shaped outline of the article located between the web members. In a subsequent operation, the narrow porous third or intermediate web member is transversely sealed to the top and the bottom web members between articles, and individual packages are formed by severing the continuously formed strip of skin-packaged articles between the articles in a manner to maintain a seal between all three web layers on each side of the path of severance.

In a preferred embodiment of this invention, the top web member is electrostatically treated so that the electrostatic forces resulting from the potential difference in the charges of the top and the bottom web members assists in draping the top web member over the article when the article is in the work area being evacuated by the suction means.

This invention further provides a method of making a hermetically sealed package consisting of an article contained between a bottom impermeable package member and a top impermeable package member including the steps of:

moving the bottom member in web form in a first direction below and in sliding contact with a fixedly positioned suction means;

moving an intermediate air-permeable package member in web form in a first direction at the same rate of speed as the bottom member and above and in sliding contact with the suction means with parts of the intermediate member resting on the upper surface of the bottom member, the intermediate member being narrower'than the bottom member and having surfaces that are heat-sealable to the bottom member and to the top member;

positioning the article on the intermediate member with side parts thereof resting on the bottom member;

heating the top member;

moving the heated top member in web form in a second direction at substantially the same rate of speed as the bottom member and into a position above the article whereby the respective movements of the bottom, top and intermediate member and article drape the top member over the article and into contact with the intermediate member and bottom member;

evacuating the region around the article lying between the bottom and top members by means of the suction means whereby the heated top membef is sealed to at least the bottom member; and

sealing the top member, bottom member and intermediate member together by means of a heat-sealing means.

According to the present invention, there is provided a package-making method including the step of continuously sealing a heated top web to a bottom web to form a package without the heated web sticking to the suction means.

This is accomplished by providing heat-shielding means for preferentially masking the suction means next adjacent the top web during the drawing of the top web into sealing contact with the bottom web. Such heat-shielding means is a part of or is operatively associated with the article and the package components; thus, the continuous movement of the top and bottom webs and the spaced articles (and hence, the continuous operation of the machine) is not affected by the heat-shielding operation. It is this combination which particularly adapts the method of the present invention to operate at high speeds, with relative simplicity of motions, and without the use of complex additional parts.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentaryperspective view of an apparatus for practicing the method of this invention of continuously making skin packages;

FIG. 2 is a longitudinal fragmentary cross-sectional view taken along lines 2-2 of FIG. 1;

FIG. 3 is a transverse fragmentary cross-sectional view taken along lines 33 of FIG. 2; and

FIG. 4 is a transverse fragmentary cross-sectional view taken along lines 4-4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, and FIG. 1 in particular, it will be seen that the present invention is embodied in a method of and apparatus for skin-packaging articles in thermoformable film.

Such package-making apparatus generally comprises a first package member supply section 10, a second package member supply section 20, a third package member supply section 30, and a package-forming section 40.

Means for driving the various mechanical components of the apparatus are shown in FIG. I and generally comprise a drive section 50.

The mechanical members or parts of the apparatus of the invention are supported by a suitable frame, not shown.

The essential components of a skin package P produced by the method and the apparatus of this invention comprise an article A, a first package member 1, a second package member 2 that is cosealable with the first package member 1, and a third package member 3 having upper and lower surfaces that are cosealable with the adjacent package members 1 and 2. Preferably, the package members 1 and 2 are of impenneable material and are in web form.

The word impermeable" as used herein does not refer to the low gas and water vapor transmission rates of the web material. Instead, it characterizes the web as one which is incapable of having air passed through it by use of a differential pressure across the two web surfaces. Thus, nonperforated organic thermoplastic webs and nonperforated fibrous and nonfibrous cellulosic webs having continuous organic thermoplastic coatings thereon are considered to be impermeable materials for purposes of this specification.

Referring particularly to FIG. 1, the articles A to be packaged by the package-making apparatus of this invention are supplied from any convenient source such as an article supply section, which includes means to feed the articles A in a predetermined path to the package-forming section 40. Such feed means consists of an endless conveyor 5 which is adapted to move the articles A continuously in the direction indicated by arrow 6 and to the package-forming section or area 40. The endless conveyorS is appropriately mounted for movement and may be of any suitable material.

The article supply section, not shown, is preferably provided with a sensor means for monitoring the flow of articles. The sensor means may be in the form of a proximity switch adapted to halt the operation of the apparatus upon detecting the absence of any flow of articles A in the supply section.

The first package member or bottom web 1 is supplied to the apparatus from a first package member supply roll 7 and is carried through the apparatus in cooperative association with an endless bottom web conveyor 8. The conveyor 8 and the other components of the apparatus are mounted on an apparatus frame, not shown, and are driven from the main drive 50.

An evacuation nozzle or suction means 9, shown in its preferred location in FIG. 2, is connected to a vacuum-forming means 11 for sucking air from between the package members l and 2. The evacuation nozzle 9 is positioned in a fixed location so that it is in substantial alignment with the upper run of endless conveyor 8. This enables the bottom web 1 to be passed directly under and around the evacuation nozzle 9 and the third package member or intermediate web 3 to be passed directly above the evacuation nozzle 9 so as to extend along and be superimposed with the bottom web I on each side of the evacuation nozzle or suction means 9.

The intermediate web 3 preferably is porous and is supplied from an intermediate web supply roll 12 in a manner known to the art.

The second package member or top web 2 is supplied to the apparatus from a top web supply roll 13 via a pair of tension control rolls 14.

Located along the path of the top web 2 is a top-web-heating means 15 consisting of a series of radiant-heating elements, not shown, for preheating the top web 2 prior to its passage to the package-forming section 40 of the apparatus.

The skin packages P made by the method of this invention are formed by concurrently moving the bottom web I, the heated top web 2, the intermediate web 3 and the article A into proximate locations with respect to the fixed evacuation noule or suction means 9. In the package-forming position, as shown, the article A rests on the intermediate web 3 that is narrower in transverse dimension than is the bottom web I which. in turn, lies beneath the article A and the web 3 while the suction means 9 generally lies between the bottom web 1 and the intermediate web 3.

The intermediate web 3 extends across both sides of the fixed evacuation nozzle 9 and contacts the bottom web 2 in a nonslipping superimposed relationship at least along each longitudinal side of the suction means 9.

The heated top web 2 is draped over the bottom web 1, the intermediate web 3 and the article A, as shown in FIG. 1, so as to have transverse contact between the bottom and top webs l and 2. As this combination of components passes by the suction means 9, as shown in FIG. 2, the air in the region around the article A between the bottom and top webs 1 and 2 is substantially removed by the suction means 9 so as to cause the preheated top web 2 to adhere to or be sealed to at least the bottom web 1. It is desirable when employing certain web combinations to employ a heated plate beneath the upper run of the endless conveyor 8 in the vicinity of the package-forming area 40 in order to preheat the bottom web 1 also.

The bottom ans top webs l and 2 are then sealed between articles to the intermediate web 3 by a heat-sealing means 16, as shown in FIGS. 1 and 2. This sealing means 16 rotates about a fixed axis, not shown, and effects a bond between the top web 2 and the intermediate web 3 and between the bottom web 1 and the intermediate web 3 in a lane of substantial width. This sealing means or bar 16 can also contain a cutting device or, as shown diagrammatically in FIG. 1, a synchronized rotating severing means or blade 17 can be used to form individual packages P by severing the continuous strip of intermittently positioned skin-packaged articles A between the article locations and within the transverse heat-sealed lanes so that the effective seals between the three continuous webs 1, 2 and 3 of thepackage P remain on both sides of the path of severance.

A cross-sectional view of a typical package P produced by use of this invention is shown in FIG. 4.

The method of this invention of continuously making a skin package P consisting of an article A or articles contained between a first web 1 and a second web 2 of impermeable, thermoplastic material includes the steps of:

moving the first web 1 below and adjacent to the fixed suction means 9;

passing the article A above the suction means 9 at substantially the same rate of speed as the first web 1 and a third web 3; moving the third web 3 in a first direction at the same rate of speed as the first web 1 and above and in sliding contact with the suction means 9 with parts of the third web 3 resting on the upper surface of the first web 1, the third web 3 being narrower than the first web I and having surfaces that are heat-scalable to the first web 1 and to the second web 2;

heating the second web 2;

moving the heated second web 2 in a second direction at substantially the same rate of speed as the first web 1 and into a position above the article A whereby the respective movements of the webs l, 2 and 3 and the article A drape the second web 2 over the article A and into contact with the third web 3 and the second web 2;

evacuating the region around the suction means 9 and the article A lying between the first and second webs l and 2 sealing the second web 2 to the first web 1 at least except in the area of the third web 3; and

sealing the first web 1, the third web 3 and the second web 2 together in the area of the third web 3 to form a hermetically sealed package P being substantially free of air therewithin.

In the preferred method of this invention for making a skin package P, an electrostatic web-treating means 18 is also em ployed to charge the top web 2 with reference to the electrostatic potential of the bottom web 1. A suitable treating means 18 for effecting this electrostatic charge is disclosed in US. Pat. No. 3,462,909 to Anderson.

As shown in FIG. 2, in this method the web 2 is passed between a planar array of electrodes 19 and a grounded conductive plate 20. A second grounded conductive plate 21 is located directly below the upper run of the endless conveyor 8. A high direct-current voltage is impressed between the planar array of electrodes 19 and ground to establish an electrostatic field in the region through which the top web 2 passes causing an electrostatic charge to form on the passing web 2 and electrostatic forces to exist between the top web 2 and the bottom web 1 which is maintained at substantially ground potential by the presence of grounded conductive plate 21. These electrostatic forces existing between the top web 2 and the bottom web I combine with the forces resulting from the differential pressure existing across the surfaces of the two webs l and 2 as a result of the action of the suction means 9 and cause the top web 2 to closely conform to the configuration of the article A and to be bonded to or be sealed to the cooperating surface of the bottom web 1.

If desired, the evacuation nozzle 9 can be in a flattened configuration and positioned in a fixed location so that its lower flattened surface is in substantial alignment with the upper run of the endless conveyor 8. Thus, the bottom web 1 would pass directly under the flattened evacuation nozzle 9 and the porous web 3 would pass directly above the flattened evacuation nozzle 9 and would extend to and be superimposed with the bottom web 1 on each side of the evacuation nozzle'9. When this embodiment is employed, the bottom web 1 need not be a flexible web since it is not caused to pass around the lower confines of the evacuation nozzle. This permits coated paperboard stock to be employed as the lower impermeable web material.

The article A being skin packaged by the method and the apparatus of this invention can consist of a single unit, such as a cut of meat, or it can consist of a group of individual items such as a group of frankfurters or cans. If a fairly wide group of items is being packaged, more than one evacuation nozzle or suction means 9 can successfully be employed in a cooperative association with one another such that the entire region around the group of items is evacuated by the group of nozzles. In such an arrangement, the porous web 3 is widened that it covers the top portions of all of the evacuation nozzles 9 employed and it joins with the bottom web 1 beyond the evacuation region.

Coated regenerated cellulose and many flexible organic thermoplastic films can be used as the web material in one or more of the requisite webs in this invention. Examples of organic thermoplastic film materials that can be used solely or in composite webs include polyethylene, polypropylene ionomers and other similar thermoplastic materials.

The thickness of the bottom and top webs l and 2 of the package P made by this invention can vary depending on the type of web material employed. Thicknesses in the 0.0005 inch to 0.004 inch range are commonly used. The essential requirement is that the webs must be flexible enough to form packages having smooth top and bottom webs or laminates. The heavier gauge webs are used in the preferred embodiment where electrostatic forces are employed to assist in the forming, attracting and sealing of the preheated top web 2 around the confines of the articie A being packaged and to the other two webs l and 2.

The paperboard stocks which can be employed as the bottom web 1 in fabricating a skin package P by the present invention are normally bleached paperboard stocks that are coated with a clay or a carboxyl methyl cellulose coating and either top-primed or coated with an extrusion, hot-melt or aqueous dispersion coating of a thermoplastic material such as a polyolefin. Since the material of the bottom web 1 preferably is impermeable, there is no need to carefully control the coating process and materials in order to maintain board porosity as is normally done in preparation of such board for use in known skin-packaging methods.

The third or intermediate web 3 can be fabricated from a double-coated and perforated cloth, kraft paper. reinforced kraft and thermoplastic materials. The stronger types of materials are preferably used when the narrow porous web 3 is intended to be used as a tear-opening device. In packages employing such dual-function porous tapes, notches are usually cut at the packages outer edge where the porous web 3 terminates in order to provide a quick-opening feature for the finished package P.

The intermediate web 3 serves a dual function. The first, and most important, is a heat-shielding function for separating or shielding the top heated web 2 from the suction means 9 during the draping and drawing of the top web 2 over the article and into contact with the bottom web 1. By positioning the web 3 between the top web 2 and the suction means 9-actually, it overlaps and completely covers the suction meansthe heated top web 2 is prevented from contacting the suction means 9 and sticking to it due to its heated or tacky state and, hence, preventing its sliding clear of the stationary suction means 9 as the webs move therepast. Since the suction means 9 is required to be positioned, or at least is preferably positioned, to extend in the direction of movement of the webs and since the suction means 9 must be positioned between the webs 1 and 2 to be able to suck air from between them after they have been brought together along substantially all of their opposed surfaces (i.e., in all their surface-contacting areas except in the area occupied by the third web 3), any web touching the suction means 9 must be capable of slidingly contacting it during movement. For the unheated first web 1, this is no problem; for the heated second web 2, it is; hence, the shielding means or web 3 is positioned between the top web 2 and the suction means 9 to solve this problem and prevent sticking during the packaging operation.

Preferably, the shielding intermediate web 3 is air-permeable to permit the suction means 9 to effectively suck air from between the webs l and 2. And it is further important to note that shielding web 3 in the finished package P serves as a tear strip; thus, the dual function.

It is important to obtain good initial contact between the top web 2 and the bottom web 1 in the initial stages of the package-making step. The relative motion of the article A on the bottom web 1 into the top web 2, of course, brings about some initial contact between the webs l and 2 during the initial draping of the top web 2 over the article A. This contact may be dramatically enhanced by the use of electrostatic treating techniques as has been explained and, also, it is contemplated that this invention can include mechanical or pneumatic means to accomplish good initial contact between the webs l and 2. It is important to note that by establishing this contact, tenting is dramatically reduced and, in so doing, the amount of air entrapped is reduced, whereby the suction requirements are considerably lessened.

it is particularly difficult to effectively skin package highprofile articles because the increased distance between the top and bottom packaging members or webs l and 2 creates excessive tenting" (the presence of air between the webs produces a ballooning effect) and increases the time it takes the top web 2 to reach the bottom web 1 during the packagefonning operation.

The use of extreme or constant high vacuum will decrease "tenting" but often some air remains and prevents the top web 2 from being brought into skinlike engagement with the article A, hence, creating undesirable wrinkles in the formed package,

Further, in packaging high-profile articles, it is difficult to evacuate the package effectively and the air pockets that remain adversely affect package appearance. This is particularly so if the package-making operation is continuous; in fact, effective evacuation in a continuous operation following known practices is essentially impossible.

This invention solves this problem of packaging high-profile articles A continuously by draping the top web 2 over the article A and by drawing it using suction into contact with the bottom web 1 and skinlike engagement with the article A and, additionally, if required, by treating either of the webs l or 2,

such as by electrostatic discharge, whereby they will positively and quickly seek contact with each other.

The method of this invention is capable of making satisfactory packages P from a wide variety of films. For example, such film may be of any suitable organic thermoplastic material, such as polyethylene, ethylene/vinyl acetate copolymers, ionomers, polyamides, polystyrene, polyvinyl chloride. vinylidene chloride/vinyl chloride copolymers. coated polyesters and the like.

A preferred film to be used in the practice of this invention is an ionomer film, available commercially under the trademark Iolon, owned by E. I. du Pont de Nemours and Company. its properties make this film particularly suitable for use in the present invention.

We claim:

1. A method of making a hermetically sealed package consisting of an article contained between a bottom package member and a top package member, such method including the steps of:

moving an intermediate permeable package member in web form in a first direction at the same rate of speed as the bottom member and above and in sliding contact with the suction means with parts of the intermediate member resting on the upper surface of the bottom member, the intermediate member being narrower than the bottom member and having surfaces that are heat-scalable to the bottom member and to the top member;

heating the top member;

moving the heated top member in web form in a second direction at substantially the same rate of speed as the bottom member and into a position above the article whereby the respective movements of the bottom, top and intermediate members and the article drape the top member over the article;

evacuating the region around the article lying between the bottom and top members by means of the suction means whereby the top member is drawn into skinlike engagement with the articles and into sealing contact with at least portions of the bottom member; and

2. The method of claim 1 further including the step of electrostatically charging the top member before it is sealed to the bottom member.

3. The method of claim 1 further including the step of sealing the top, bottom and intermediate members together between articles being packaged.

4. The method of claim 3 further including the step of severing the individually packaged articles within the seal between the packages so that an effective seal remains after severance.

5. A method of continuously making a skin package consisting of an article contained between a first web and a second web of thermoplastic material including the steps of:

moving the first web below and adjacent to a fixed suction means;

moving a third web of permeable material at the same rate of speed as the first web above and adjacent to the suction means and into contact with the upper surface of the first web on both sides of the suction means, the third web being narrower than the first web and having surfaces that are heat-scalable to the first and second webs;

heating the second web;

passing the article above the suction means at substantially the same rate of speed as the first and third webs;

moving the heated second web at substantially the same rate of speed as the first web into a position above the article and above a portion of the first and third webs; and

evacuating the region around the suction means and the article lying between the first and second webs so as to cause the heated second web to seal to at least the first web by means of the external force acting on the first and second webs resulting from the differential pressure existing across the surfaces of the first and the second webs.

6. The method of claim further including the step of transverse sealing the first, second and third webs together in lanes located between consecutively packaged articles.

7. A method of packaging including the steps of:

placing the article on an intermediate web of material with at least parts of the article resting on the intermediate web and other parts of the article resting on the bottom web, the intermediate web being positioned between the top web and a suction means whereby such intermediate web shields the top web from the suction means;

heating at least the top web to render it drapable;

moving the article and the top web relative to each other thereby to drape the heated film over the article; withdrawing air from between the top and bottom webs by means of suction whereby the top web is drawn into skinlike engagement with the article and whereby the top and bottom webs are drawn into engagement with each other along at least the side edges thereof to seal these edges together and are drawn into engagement with each other along at least portions of the leading and trailing edges thereof to at least partially seal these edges together, the suction being applied by means of the suction means extending between the top and bottom webs and extending in the direction of movement of the webs and below the article whereby the article slides over the suction means as the article is carried by the bottom web;

removing the suction means from between those portions of the webs forming an individual package;

sealing any unsealed portions of the leading and trailing edges of the top and bottom webs together after the suction means has cleared the trailing edge;

sealing the top web to the bottom web at least except in the area of the intermediate web by means of suction; and

sealing the bottom web, the intermediate web and the top web together in the area of the intermediate web to form a hermetically sealed package being substantially free of air therewithin.

Claims

1. A method of making a hermetically sealed package consisting of an article contained between a bottom package member and a top package member, such method including the steps of: moving the bottom member in web form in a first direction below and in sliding contact with a fixedly positioned suction means; moving an intermediate permeable package member in web form in a first direction at the same rate of speed as the bottom member and above and in sliding contact with the suction means with parts of the intermediate member resting on the upper surface of the bottom member, the intermediate member being narrower than the bottom member and having surfaces that are heat-sealable to the bottom member and to the top member; positioning the article on the intermediate member with side parts thereof resting on the bottom member; heating the top member; moving the heated top member in web form in a second direction at substantially the same rate of speed as the bottom member and into a position above the article whereby the respective movements of the bottom, top and intermediate members and the article drape the top member over the article; evacuating the region around the article lying between the bottom and top members by means of the suction means whereby the top member is drawn into skinlike engagement with the articles and into sealing contact with at leaSt portions of the bottom member; and sealing the top member, bottom member and intermediate member together by means of a heat-sealing means.

5. A method of continuously making a skin package consisting of an article contained between a first web and a second web of thermoplastic material including the steps of: moving the first web below and adjacent to a fixed suction means; moving a third web of permeable material at the same rate of speed as the first web above and adjacent to the suction means and into contact with the upper surface of the first web on both sides of the suction means, the third web being narrower than the first web and having surfaces that are heat-sealable to the first and second webs; heating the second web; passing the article above the suction means at substantially the same rate of speed as the first and third webs; moving the heated second web at substantially the same rate of speed as the first web into a position above the article and above a portion of the first and third webs; and evacuating the region around the suction means and the article lying between the first and second webs so as to cause the heated second web to seal to at least the first web by means of the external force acting on the first and second webs resulting from the differential pressure existing across the surfaces of the first and the second webs.

6. The method of claim 5 further including the step of transverse sealing the first, second and third webs together in lanes located between consecutively packaged articles.

7. A method of packaging including the steps of: positioning an article to be packaged between a top web and a bottom web of plastic film, with at least parts of the article resting on the bottom web; placing the article on an intermediate web of material with at least parts of the article resting on the intermediate web and other parts of the article resting on the bottom web, the intermediate web being positioned between the top web and a suction means whereby such intermediate web shields the top web from the suction means; heating at least the top web to render it drapable; moving the article and the top web relative to each other thereby to drape the heated film over the article; withdrawing air from between the top and bottom webs by means of suction whereby the top web is drawn into skinlike engagement with the article and whereby the top and bottom webs are drawn into engagement with each other along at least the side edges thereof to seal these edges together and are drawn into engagement with each other along at least portions of the leading and trailing edges thereof to at least partially seal these edges together, the suction being applied by means of the suction means extending between the top and bottom webs and extending in the direction of movement of the webs and below the article whereby the article slides over the suction means as the article is carried by the bottom web; removing the suction means from between those portions of the webs forming an individual package; sealing any unsealed portions of the leading and trailing edges of the top and bottom webs together after the suction means has cleared the trailing edge; sealing the top web to the bottom web at least except in the area of the intermediate web by means of suction; and sealing the bottom web, the intermediate web and the top web together in the area of the intermediate web to form a hermetically sealed package being sUbstantially free of air therewithin.