U.S. patent number 3,566,752 [Application Number 04/751,967] was granted by the patent office on 1971-03-02 for method of forming a tear strip on a packaging sheet.
This patent grant is currently assigned to General Cigar Co. Inc.. Invention is credited to Hans C. Dreher.
United States Patent |
3,566,752 |
Dreher |
March 2, 1971 |
METHOD OF FORMING A TEAR STRIP ON A PACKAGING SHEET
Abstract
This invention relates to the formation of a tear strip on a
packaging sheet having a surface which is heat or pressure
sealable. By trimming a narrow strip from the packaging sheet and
sealing the trimmed strip to the surface of packaging sheet, a
packaging sheet with an affixed tear strip of the same sheet
material is produced.
Inventors: |
Dreher; Hans C. (Dallas,
PA) |
Assignee: |
General Cigar Co. Inc. (New
York, NY)
|
Family
ID: |
25024275 |
Appl.
No.: |
04/751,967 |
Filed: |
August 12, 1968 |
Current U.S.
Class: |
493/197; 53/479;
156/264; 383/205; 493/207; 493/963; 53/412; 156/260; 229/87.05;
493/923 |
Current CPC
Class: |
B31B
50/00 (20170801); Y10S 493/963 (20130101); Y10T
156/1069 (20150115); Y10S 493/923 (20130101); Y10T
156/1075 (20150115); B31B 50/8126 (20170801) |
Current International
Class: |
B31B
1/90 (20060101); B31B 1/74 (20060101); B31d () |
Field of
Search: |
;93/1(TS) ;329/5(RT)
;156/260,264,512 ;53/14 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Stickney; Bernard
Claims
I claim:
1. The method of continuously forming a contrasting tear strip on
an opaque packaging sheet comprising a laminated paper and metal
foil with a heat-sealable coating on the paper surface of said
packaging sheet which comprises:
a. drawing said packaging sheet and cutting therefrom a tear strip
of desired width;
b. guiding and inverting said tear strip to a desired position on
said packaging sheet parallel to an edge thereof in such manner
that said sealable coating on said paper surface of said packaging
sheet contacts said sealable coating on said paper surface of said
tear strip; and
c. sealing with heat said tear strip to said packaging sheet by
means of the two contacting thicknesses of said sealable coating
disposed therebetween.
Description
BACKGROUND OF THE INVENTION
This invention relates to the method of continuously cutting a tear
strip from a roll of a packaging sheet having a surface which is
heat or pressure sealable and affixing the tear strip to the
surface of the packaging sheet thereby obviating the use of threads
and other materials conventionally applied to packaging sheets as
tear strips.
Numerous prior patents teach that pouches or packages can be formed
to include a tear strip sealed to the surface of the packaging
sheet to facilitate opening the finished package. Illustrative are
U.S. Pat. Nos. 2,970,736 granted Feb. 7, 1961, to Baughan,
3,057,539 granted Oct. 9, 1962, and 3,181,438 granted May 4, 1965,
both to Leary, which disclose that a pouch material comprising
laminations of metal foil, fibrous papery material and a coating of
thermoplastic material is suitable for manufacturing a
heat-sealable container with leakproof joints. Furthermore, U.S.
Pat. No. 2,683,401 granted Jul. 13, 1954 to Smith shows that narrow
rip strips can be cut from a wide roll of strip-forming material
just prior to applying the narrow strip to a packaging material,
thus precluding problems which arise from handling narrow coils of
rip strip material. In addition, U.S. Pat. No. 2,475,052 granted
Jul. 5, 1949 to Rosen discloses a package with a tear strip formed
by perforating along one of the longitudinal edges of the packaging
sheet, and then folding the edge of the sheet with the perforated
strip under and parallel to the overlying remainder of the
packaging sheet. This proposal suffers from the disadvantage that a
perforated tear strip is more difficult to pull off, does not tear
cleanly and requires more of the packaging sheet for the folded
portion.
SUMMARY OF THE INVENTION
By contrast, the present invention requires only that a flexible
packaging sheet having at least one surface which is heat or
pressure sealable be cut to form a tear strip of desired width as
the sheet is continuously withdrawn from a roll thereof and that
the tear strip cut from the sheet be adhered to the heat or
pressure sealable surface of the packaging sheet without the use of
any extraneous adhesive or other added material.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic representation showing one method of
continuously trimming a tear strip from a roll of packaging sheet,
and inverting, positioning and sealing this tear strip onto the
packaging sheet as it is longitudinally advanced;
FIG. 2A is a transverse sectional view of a typical metal foil,
paper and polyethylene laminate where the polyethylene coating on
the tear strip portion has been sealed to the same polyethylene
coating of the laminate packaging sheet;
FIG. 2B shows a similar section of a packaging metal foil having a
pressure-sensitive coating with a tear strip of the same foil
attached thereto;
FIG. 3 shows a segment of packaging sheet with a tear strip of the
same sheet affixed on the sheet and a tab cut on one edge of the
segment;
FIG. 4 shows in perspective the sheet segment of FIG. 3 wrapped
around five cigars with the tear strip inside the partially formed
pouch and the tab on the outside of the pouch; and
FIG. 5 shows the pouch of FIG. 4 in the completed form with the
opposite ends folded and sealed.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows packaging sheet 2 being drawn from a roll thereof with
its sealable surface 4 uppermost and metal foil surface 5 undermost
over cutting roller 6 which has a peripheral groove 8 cooperating
with rotary cutting blade 10. Tear strip 12 is thus continuously
trimmed from one edge of sheet 2 to an appropriate width, then
looped over to invert the strip and bring its sealable surface 4
into contact with the same surface of the remainder of packaging
sheet 2. Tear strip 12 is positioned on packaging sheet 2 by guide
bar 14 having a rectangular channel 16 milled therein. Strip 12 is
held loosely in channel 16 by guide cover 18 that drops into
channel 16 and is supported on bar 20 which is arcuately movable on
pivot 22.
As packaging sheet 2 is continuously advanced longitudinally with
tear strip 12 in an overlying position, sealer bar 24 of sealing
unit 30 seals tear strip 12 to packaging sheet 2 which is supported
by inverted bristle brush 34 positioned directly under sealer bar
24.
If packaging sheet 2 has a film or coating thereon which is heat
sensitive or sealable, heater 26 is provided in conjunction with
thermostat 28 to maintain sealer bar 24 at the proper temperature
to effect the sealing of tear strip 12 to packaging sheet 2. If
packaging sheet 2 has a film or coating thereon of a pressure
sensitive material, sealing unit 30 does not require heater 26.
Inverted brush 34 is on an adjustable support (not shown) which may
be adjusted to provide the desired amount of pressure against
sealer bar 24 depending on the heat and/or pressure sensitive
character of the film or coating on packaging sheet 2. Other known
means, such as a tandem series of rollers, may be used in place of
inverted brush 34 to cooperate with sealer bar 24 and apply the
desired pressure thereagainst.
It is obvious that two widths of packaging sheet with tear strips
of the same packaging sheet may be produced simultaneously by this
method by trimming both edges of sheet 2 and employing paired
cutting blades 10, guide bars 14 and sealing units 30, and then
slitting packaging sheet 2 longitudinally. It is also possible to
make a single packaging sheet with two tear strips of the same
sheet.
After tear strip 12 is affixed to packaging sheet 2, sheet 2 is
guided over idler roller 36 and led between driven roller 38 and
friction roller 40 which jointly act to pull packaging sheet 2 from
the roll thereof. If desired, driven roller 38 may be linked with a
Geneva gear (not shown) which intermittently advances sheet 2 under
knife 42 to cut segments 46 from sheet 2. To make tear strip 12
readily available, knife 42 is preferably shaped in the area of
portion 44, aligned with tear strip 12, to cut tab 48 which
concommittantly results in cutout 50 being formed on the opposite
edge of sheet segment 46 as will be seen in FIG. 3.
As known, each sheet segment 46 can be wrapped around one or more
articles 52 and sealed at overlap 54 as shown in FIG. 4 wherein
articles 52 are illustrated as five cigars. To form a pouch or
package, opposite ends 56 of sheet segment 46 are folded in and
transversely sealed along edges 58 as shown in FIG. 5. At the same
time, tab 48 is folded back over the sealed overlap so that tear
strip 12 becomes visible at the point where it is to be pulled to
open the sealed package.
The method of this invention is particularly applicable to
laminates comprising a metal foil and a film or coating on one
surface of the laminate that is pressure or heat sensitive. FIG. 2A
shows a laminate cross section of polyethylene film 4, paper 3 and
metal foil 5 with protective coating 7; FIG. 2B shows a cross
section of metal foil 13 bonded to thermoplastic layer 17. In both
FIGS. 2A and 2B, tear strip 12 of the same respective packaging
sheet is shown attached to its sheet in the inverted position,
i.e., the sealable surface of strip 12 is attached to the same
sealable surface of the sheet. This inversion of the tear strip is
preferred not only because it facilitates and ensures better
adhesion of the tear strip to the packaging sheet but also because
in nearly all instances the two surfaces of the packaging sheet are
different in color and/or texture so that the inverted tear strip
will be more conspicuous against the packaging sheet.
In a specific example of the invention involving the packaging of
cigars in the form of five-pack sealed pouches, a
rotogravure-printed aluminum foil of 3.5 mil thickness is
overcoated with a thin application of lacquer to protect the print
to ensure the resistance of the foil to moisture vapor
transmission. The other surface of the foil is laminated to a
25-pound bond paper. This paper has a half mil of polyethylene
coating on its other surface which will form the inside surface of
the finished pouch. A roll of this packaging sheet is passed
through the processing equipment illustrated in FIG. 1 with the
metal foil of the laminate facing down. A tear strip of
approximately 1/8-inch width is trimmed from a longitudinal edge of
the packaging sheet, is continuously inverted so that the
polyethylene surface of the tear strip is adjacent to the
polyethylene surface of the packaging sheet, is guided into a
desired position, and is heat sealed to the packaging sheet.
The resulting packaging sheet with the attached tear strip can then
be rolled onto spools for storage or fed directly into a packaging
machine in which segments as shown in FIG. 3 are cut and formed
into a sealed pouch containing cigars as shown in FIGS. 4 and
5.
The polyethylene coating on the paper-metal foil laminate was
selected for this specific example because it is readily heat
sealable, does not block with the cellophane overwrapping on the
cigars and increases the resistance of the pouch to moist vapor
transmission.
In view of the many possible modifications and variations of the
invention which will occur to those skilled in the art without
departing from the spirit or scope of the invention, only such
limitations should be imposed as are indicated by the appended
claims.
* * * * *