US3664498A

US3664498A - Package including envelope with heat-shrunk band

Info

Publication number: US3664498A
Application number: US861325A
Authority: US
Inventors: Fred C Dulmage
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1969-09-26
Filing date: 1969-09-26
Publication date: 1972-05-23
Anticipated expiration: 1989-05-23

Abstract

Strips of shrinkable material are secured to edge regions of a film package, and heat is applied to shrink the strips and thereby secure the package in such regions. For example, two such strips can be secured to opposite edges of a length of film, and the film wrapped as a sleeve about one or more articles such that the strips comprise peripherally continuous bands at the sleeve ends, respectively. Shrinking the bands gathers and secures the sleeve ends in a drawstring-like fashion.

Description

United States Patent Dulmage May 23, 1972 [s41 PACKAGE INCLUDING ENVELOPE 1,958,033 5/1934 Cohn ..206/45.34 ux WITH HEAT-SHRUNK BAND 1,937,468 1 1/1933 Talbot ..206/59 A X 9 3,093,448 6/ l963 Kirkpatrick et al.. ....229/DlG. I2 [72] FM ohm 2,751,952 6/1956 Mirus ..229/3.5 ux [73] Assignee: The Dow Chemical Company, Midland,

Mich. Primary Examiner-Leonard Summer AttorneyGriswold and Burdick, Burke M. Halldorson and [22] sept' 1969 Richard G. Waterman [2l] Appl. No.: 861,325

[57] ABSTRACT 206/4533, /D| l2 Strips of shrinkable material are secured to edge regions of a [51] lnLCl. ..B65d 71/00, 865d 65/ 16 m package and heat is appued w Shrink he strips and [58] Field of Search ..206/65 S, 65 C, 65, 45.33; thereby Secure the package in Such regions For examph' two 229/DIG- such strips can be secured to opposite edges of a length of film, and the film wrapped as a sleeve about one or more arti- [56] References and cles such that the strips comprise peripherally continuous UNITED STATES PATENTS bands at the sleeve ends, respectively. Shrinking the bands gathers and secures the sleeve ends 1n a drawstrmg-hke 3,262,245 7/1966 Snow ..206/45.33 X f hi 3,215,266 ll/l965 Dreyfus....

l2/l949 Magid 150/52 X 7 Claims, 9 Drawing Figures PATENTEDHAY 23 1912 INVENTOR. Frederick C. Du/n') O96 8% fla -441mm ATTORNfY PACKAGE INCLUDING ENVELOPE WITH HEAT- SHRUNK BAND DESCRIPTION OF THE PRESENT INVENTION The present invention is directed toward improvedpackaging concepts and has particular applicability toward those areas'where shrink films are employed to obtain an envelope or casing havinga tight fit about the article or articles it encloses.

It is therefore among the objects of the. present invention to provide:

Afilm package .wherein portions of the package are drawn closed or partially closed-by the use of bands or strips of shrinkable material;

A film package of a construction that permits shrinkage to occur at localized or strategic regions thereof, such as regions where it is most needed as relates to certain package designs;

A film package of a construction that assists in obtaining higher rates in its production or manufacture; and

A film package whereinthe thickness and/or shrink energy requirements of the film can be lessened somewhat to obtain economies in material costs while still maintaining-the quality of the package at a satisfactory level.

Briefly then, the present invention pertains to a film package construction wherein bands of high shrink energy material are employed at end or edge regions of the package to tightly gather and secure the film at such regions.'The use of such bands is applicable to both overwrap packaging concepts and preformed plastic bags. Specifically, such bands operate on a drawstring-like principle in that when subjected to.ap propriate amounts of heat, they contract rapidly to assist in pulling and gathering the film tightly about the enclosed product. A greater latitude in the selection of films for various shrink film packaging application is thus permitted.'Specifically, film selections can now be made giving more weight to factors, such as film costs or functionality, particularly film toughness as measured by tear resistance, impact resistance and the like, and discarding to an extent the shrink energy properties of the film. Still further benefits of the invention can reside in the reinforcement of the film edges at the ends of the package, due to the provision of such bands, thereby better permitting such ends to serve as carrying handles forthe package.

The preferred embodiments of the present invention are shown in the accompanying drawings wherein, wheresoever possible, like reference numerals designate corresponding materials andparts throughout the several viewsthereof in which:

FIG. 1 is an end view of an overwrap-type 'film bundle package constructed according to the principles of the present invention;

FIG. 2 is a side view with parts broken away, of the package of FIG. 1;

FIG. 3 is an enlarged fragmentary view of the upper right hand portion of the package of FIG. 2;

FIG. 4 is a top view of aJength of film of a construction suitable for use in assembling; the package of FIG. I;

FIG. 5 is a cross-sectional view of the film of- FIG. 4-taken along reference line 5-5 thereof;

FIGS. 6 and'7 are views like FIG. 5 only showing modified forms of the invention;

FIG. 8 is a top view of a package including a film bag constructed according to the principles of the present invention; and

FIG. 9 is a cross-sectional view of the package of FIG. 8 taken along reference line 99 thereof.

Referring now more particularly to the drawings, there is shown in FlGS. 1-3 a package 10 comprising a plurality of metal cans 12 positioned on their sides and stacked in two rows Hand 16 of four cans each. -Surrounding cans 12 is a tight fitting film envelope or sleeve 18 which is shrink fitted about cans 12 to securely bundle them together in their illustrated stacked relationship. Sleeve 18 characteristically includes openings or open regions 20and 22 at each of its ends 24 and 26, respectfully.

Package 10 structure to the extent described above embodies certain conventional shrink packaging concepts and designs. Similar package structure and their methods of manufacture including shrink film-selections, are exemplified for example, by U.S. Pat. Nos. 2,878,628, 3,087,610, 3,133,387, 3,239,991, 3,295,290 and 3,404,508. Additional conventional structure for such packages can include trays, inserts, and support members or cores of various designs and shapes to assist in retaining the packaged articles, i.e., metal cans, cartons, or the like in certain assembled relationship. For example, incorporation of such additional structure in various bundle package designs is illustrated in U.S. Pat. Nos. 2,864,212, 3,111,221 and 3,331,503.

The present invention pertains to an improvement on such known package designs in that it contemplates securing strips of shrinkable materials to certain areas of the package, particularly film edge regions, to assist in gathering and securing the film at such regions.

In the illustrated embodiment of the invention as depicted in FIGS. 1-3, two strips or

bands

28 and 30 are employed to achieve this end.

Bands

28 and 30 are fixed together with sleeve 18 at its

edges

32 and 34 defining

open regions

20 and 22, respectively. Such bands operate by means of sucker or drawstring-like principle in that upon application of appropriate amounts of heat to the ends of package 10, the bands rapidly contract to assist in gathering sleeve ends 24 and 26 into tight surrounding engagement about the cans 12, as illustrated.

Referring now to FIG. 4, package 10 can be manufactured from a length of shrink film 36 including strips of

shrinkable material

38 and 40 secured along its

side edges

42 and 44, respectfully. Specifically, film 36 is fabricated into package 10 by wrapping it endwise about cans 12 such as to form an open ended sleeve thereabout, i.e., sleeve l8-prior to shrink fitting the same. The end edges46 and 48 of film 36 are overlapped and seamed or otherwise joined together to secure the sleeve in place, as is generally indicated at 50 in FIG. 1.

Strips

38 and 40 are thus fabricated into the

aforesaid bands

28 and 30 at ends 24 and 26, respectfully.

Thereafter, sleeve 18 is shrink fitted about cans I2 such as by applying heat to ends 24 and 26, respectively, to tightly gather and secure the film at such regions, assisted by bands 28'and 30,-as described above;'and followed by heating midregions of package 10 to shrink fit the sleeve at such regions. Altemately, certain other conventional shrinking techniques can be employed such as by applying heat generally simultaneously to all regions of the package 10, such as for example, by means of a shrink tunnel, like that illustrated in U.S. Pat. No. 3,295,290.

FIGS. 5-7 illustrate various means of securing

strips

38 and 40 to

film side edges

42 and 44, respectfully. Referring to FIG. 5, film edge 44, for example, can be tunneled about strip 40 by folding the film over the strip material, and by joining the film to itself at area 52 such as by heat sealing or by the use of appropriate adhesive or glue layers. In FIG. 6 a separate layer of material 53 is employed to this end with material 53 being joined along its

opposite edges

56 and 58 to film 36 such as to encapsulate the strip between material 53 and film 36; and in FIG. 7 strip 38 is joined directly to the film 36 such as by means of an adhesive layer 54.

A low temperature adhesive system can be employed with adhesive layer 54 comprising, for example, a polyurethanetype adhesive such as is taught in U.S. Pat. No. 3,198,692. The temperature for activation of such an adhesive should be. less than that which would cause substantial shrinkage of

strips

38 and 40 at the point in time of their application to film 36. Rapid cooling of the strip material accompanying sealing, such as by use of a chill roll or by air cooling or water quenching can be beneficially employed, if necessary, to control or reduce shrinkage of

strips

38 and 40 during such operations.

Strips

38 and 40 can be employed in combination with either shrink or non-shrink films. The latter film type, of course, is normally shrinkable to a degree or has a certain level of shrink energy, but not a sufficient level that would characterize it as a shrink film.

In any event, the

material comprising strips

38 and 40 is characterized as having greater shrink energy than the film with which it is combined. Shrink energy can be defined as the measurable tension produced in a fully mono-directionally restrained strip of film when heated to a specified temperature. Sometimes shrink energy is referred to as shrink tension.

Moreover, such strip material is characterized as having a maximum percentage of shrink, i.e., shrink percentage change from original, at least commensurate or equal to the film to which it is attached. in other words, the strip material must be able to shrink in size an amount at least equal to the shrinkage of the film at ends 24 and 26, respectively, such that a drawstring-like effect is obtained.

For exemplary purposes only, a preferred material for

strips

38 and 40 comprise an irradiated polyethylene of a character, for example, as described in US. Pat. No. 3,022,543. Other materials contemplated for use as

strips

38 and 40 are such conventional shrink materials as listed in the 1968 Modern Packaging Encyclopedia, V0. 41, No. 7A, pages 222 and 223.

A modification of the present invention is shown in FIGS. 8 and 9 as embodied in a package 60 including a preformed bag 62. Bag 62 can comprise a low density, non-irradiated polyethylene such as is commonly employed in bag manufacture. Alternately, a shrink film can comprise bag 62.

Bag 62 contains a cylindrical metal container 64 closed at one end 66, such as for example, by a conventional snap-on plastic lid 68. A peripherally continuous band 70 of heat shrinkable material, i.e., of a character similar to that described with regard to

strips

38 and 40, is joined together with bag 12 at its edges defining bag opening 72. Opening 72 is gathered and drawn tightly around containers 64 by shrinkage of band 70 in a manner as described hereinbefore. The resulting package 60 is tamperproof due to the provision of bag 62 incorporating band 70. Moreover, such package can be conveniently opened by removing bag 62 therefrom and lifting snap-on lid 68 from container 64.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention.

Accordingly what is claimed as new is:

1. In a package of the general type comprising a flexible envelope and a product in the envelope, the envelope defining an open region, the improvement of which comprises, a band of separate material extending substantially peripherally about said open region and secured together with said envelope, said band comprising synthetic resinous thermoplastic material, and being in heat induced permanently set tension in the hoop direction to assist to tightly gather and secure said envelope about said product in the vicinity of said open region.

2. The package of claim 1 wherein the gathering and securing of said envelope in the vicinity of said open region is essentially entirely by means of the heat induced tension in said band.

3. The package of claim 1 wherein said band is continuous about said open region.

4. The package of claim 1 wherein said envelope comprises a preformed bag, said opening comprising the mouth of said bag.

5. The package of claim 1 wherein said envelope comprises a sleeve having open regions at its ends, and bands gathering and securing the sleeve at said open regions, respectively.

4. The package of claim 1 wherein said envelope comprises a prefonned bag, said opening comprising the mouth of said bag.

6. The package of claim 5 wherein said product comprises a plurality of objects.

7. The package of claim 6 wherein said objects are tightly bundled together by said envelope assisted by said band.