U.S. patent number 3,780,781 [Application Number 05/178,088] was granted by the patent office on 1973-12-25 for openable bag.
Invention is credited to Tatsuro Uramoto.
United States Patent |
3,780,781 |
Uramoto |
December 25, 1973 |
OPENABLE BAG
Abstract
A plastic film structure for forming a bag including a sheet of
thin plastic film with continuous shaped interlocking rib and
groove profiles thereon either integral with the film or on strips
which are fused to the film with the sheet having plastic
reinforcing strips thereon between the profiles with the
reinforcing strips providing tear guidelines for tearing off the
top of a bag formed from the sheet to thereafter provide gripping
flanges for separating the profiles and opening the bag.
Inventors: |
Uramoto; Tatsuro (Kohjimachi,
Chiyoda-ku, JA) |
Family
ID: |
22651135 |
Appl.
No.: |
05/178,088 |
Filed: |
September 7, 1971 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
882491 |
Dec 5, 1969 |
|
|
|
|
Current U.S.
Class: |
383/204; 383/65;
383/908 |
Current CPC
Class: |
B29C
66/474 (20130101); B29C 66/4722 (20130101); B65D
33/2533 (20130101); B29C 66/1122 (20130101); B65D
75/5805 (20130101); B29C 66/723 (20130101); B29C
65/02 (20130101); B29C 66/72328 (20130101); B29C
66/7234 (20130101); B29C 65/222 (20130101); Y10S
383/908 (20130101) |
Current International
Class: |
B29C
65/00 (20060101); B65D 33/25 (20060101); B65D
75/52 (20060101); B65D 75/58 (20060101); B65d
017/24 (); B65d 033/24 () |
Field of
Search: |
;150/3 ;24/21C
;229/66 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Norton; Donald F.
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of my copending
application Ser. No. 882,491 filed Dec. 5, 1969 and now abandoned.
Claims
I claim as my invention:
1. A bag structure comprising,
a bag body formed of a thin plastic film,
said film being continuous at the bag top,
facing mating interlocking profiles extending within the bag spaced
downwardly from the top edge of the bag,
a flat reinforcing strip means of plastic fused to the bag film
along the top between the top edge and said profiles defining a top
tear line spaced above said profiles.
2. A bag in accordance with claim 1 wherein said bag body has an
opening at the bottom for filling and sealing the bag.
3. A bag in accordance with claim 1 wherein said profiles are
carried by strips fused to the inner surface of the film of the bag
body.
4. A bag structure constructed in accordance with claim 1 wherein
the bag body has a seal along the top above said reinforcing strip
means.
5. A bag structure comprising,
a bag body formed of a flexible plastic film and having side walls,
interlocking rib and groove elements on the inner surfaces of the
side walls adjacent the top of the bag,
flanges projecting above the rib and groove elements for gripping
the bag and drawing the elements apart, and
strips fused to the surfaces of the flanges above the elements for
stiffening the flanges and providing improved gripping thereof.
6. A reclosable bag comprising,
a plastic film bag body being continuous at the top and closed by
seals at the sides and bottom, and
fastener strips fused to the inner surface of the bag adjacent the
top with said strips having interlocking profiles on the inner face
and a flat surface on the outer face with the flat surface being
joined to the film, with said strip containing means for tearing
open the top of the bag above the profiles along a line of weakened
tear resistance.
7. A reclosable bag structure comprising in combination, a bag body
including opposing bag walls of a flexible material, opposed
separate plastic fastener strips on the inner walls of the bag
adjacent the bag top having mating pressure interlocking separable
rib and groove elements projecting toward each other and having a
base with a flat surface extending above and below the profiles
with said base being joined to the inner surface of the bag wall,
and the upper ends of the bag walls being joined to each other at
the top of the bag to protect the bag contents above the fastener
strips.
8. A reclosable bag structure constructed in accordance with claim
7 wherein said bag walls have an inner surface of plastic and are
joined to the flat plastic base of the fastener strips by being
fused thereto above and below said rib and groove elements.
9. A reclosable bag structure constructed in accordance with claim
7 wherein the side edges of the bag are joined by cross seals and
the lower edges are joined by a bottom seal so that the bag
provides a complete barrier protecting the bag contents from both
above and below said fastener strips.
10. A reclosable bag structure constructed in accordance with claim
7 wherein the upper ends of the walls are joined by being
continuous and integral with the material of the two walls folded
at the extreme top of the bag.
11. A reclosable bag structure constructed in accordance with claim
7 wherein the opposing bag walls are of one piece and continuous at
the top of the bag.
12. A reclosable bag structure constructed in accordance with claim
7 wherein the bag walls are joined at the bottom edge of the bag
and are of one piece.
Description
BACKGROUND OF THE INVENTION
The present invention relates to improvements in plastic film sheet
structures for forming bags and the bags formed therefrom,
particularly to a structure which permits the bag to be more
readily opened.
More specifically, the invention relates to bags of the reopenable
type which have shaped rib and groove profiles extending along the
top that are openable by pulling apart top flanges above the
profiles and are reclosable by pressing the rib and groove elements
together. This type of bag is very useful for products which are
removed from the bags only a portion at a time, or where the bags
are to be reused. However, in many instances it is desirable to
provide a bag which is sealed in the store and cannot be opened
until eventually purchased. The advantages of this type of bag are
obvious for foodstuffs and like materials wherein the potential
customers must not be able to open the bag to remove a portion of
the contents or contaminate the interior.
It is accordingly an object of the present invention to provide an
improved sheet structure for forming a bag of the reclosable type
wherein the bag has a structure which is completely sealed until
used.
In the sealed reopenable type of bag, it is conventional to tear
open the top of the bag above the reclosable rib and groove
elements in such a manner as to provide flanges with which to
separate the elements. This may be done by having the side walls of
the bag either continuous or sealed at the top so that the top can
be either cut or torn above the rib and groove elements along a
line of weakened resistance or perforation before it is to be
opened. The flanges which remain at the top of the bag after it is
torn or cut enable the user to pull the rib and groove elements
apart for access to the bag interior.
It is an object of the invention to provide a reclosable bag of the
sealed type with an improved tearing strip arrangement at the top
which permits the bag to be made of very thin lightweight material
or a laminated material. A feature of the present invention is to
provide a bag structure wherein a tear line, where the film is too
thin to be scored or perforated is required, or where because the
film is of laminated construction and has sub-stantially greater
strength, additional tearability or tear guidance is required, or
wherein the functions of the interlocking rib and groove elements
are not encumbered because of the thinness of the material, so that
the provision of an easy to remove, yet strong tear strip at the
top of the bag is permitted.
Various modifications, forms and arrangements of the invention are
intended to be embodied and will become apparent to those skilled
in the art from the teaching of the principles of the invention in
connection with the disclosure of the claims, specification and
drawings, in which:
IN THE DRAWINGS
FIG. 1 is a plan view of a plastic film sheet structure for forming
a bag in accordance with the principles of the present
invention;
FIG. 2 is an elevational view of a bag formed from the sheet
structure of FIG. 1;
FIG. 3 is a vertical sectional view taken substantially along the
line III--III of FIG. 2;
FIG. 4 is a fragmentary view shown in perspective illustrating a
tear strip being removed from the top of a bag;
FIGS. 5 thru 10 are vertical sectional views similar to FIG. 3
illustrating different arrangements embodying the concepts of the
invention;
FIG. 11 is a fragmentary sectional view taken substantially along
line XI--XI of FIG. 10; and
FIGS. 12 thru 14 are vertical sectional views illustrating
additional arrangements embodying the concepts of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a thin plastic film sheet of polyethylene or similar
plastic material of the type used in thin bags. The sheet has side
edges 12c and 12d which will later form the bottom of a bag 19 as
shown in FIG. 2. The sheet has front and rear edges 12a and 12b
which will later form the side edges of the bag 19 of FIG. 2. The
sheet is preformed such as by a plastic extrusion process, and will
usually be formed in a continuous running strip and cut into
sections as shown in FIG. 1. When formed into a bag, the sheet is
doubled or folded down its center 12e to form the top of the bag as
shown in FIGS. 2 and 4. When doubled, seams will be formed to join
the doubled edges 12a and 12b to provide side seams for the bag.
When a series of bags are made from a continuous running sheet, the
seaming and cutting can be formed in a simultaneous operation such
as by a hot wire cutter and seamer as will be recognized by those
versed in the art.
Fused to the upper surface of the sheet (which will form the
interior of the bag after the sheet is folded and side sealed) are
a pair of plastic reinforcing strips 13 and 14. These reinforcing
strips carry the interlocking rib and groove elements with the rib
element shown at 13a and the groove element at 14a. These elements
are complementary shaped so as to interlock when pressed together
and to separate when forcibly pulled apart. It should be noted that
said reinforcing strips can initially be formed as one piece.
The reinforcing strips 13 and 14 also function to define a tear
line for removing a strip 17a from the top of the bag in the manner
shown in FIG. 4. The tear line is formed by lines 13b and 14b of
weakened resistance so that when the top of the bag 19 is gripped
and pulled to the side or upwardly, as shown in FIG. 4, the strip
17a will be torn from the bag in a relatively straight line along
the tear lines 13b and 14b. This will leave flanges 17 and 18 which
can be gripped and pulled apart to forcibly separate the rib and
groove elements 13a and 14a. The remaining part of the reinforcing
strips also strengthen and stiffen the film flanges above the
profile. If too thin a film is being used from which to make the
bags, the opening flanges above the profile would bend at the point
the profile stem joins the film and would not separate the
profile.
In summary with respect to the sheet structure of FIG. 1, when it
is to be formed into the bag 19 of FIG. 2, it is doubled down its
center 12e to form a fold for the top of the bag, and the sides 12a
and 12b are seamed with the bottom edges 12c and 12d remaining
unattached to leave a bottom opening for filling the bag. The rib
and groove elements 13a and 14a are pressed together to interlock
so that the contents of the bag will not flow past these
interlocked elements. When the contents are placed in the bag, a
seam is formed along the bottom to join edges 12c and 12d to form a
seam 16 as shown in FIG. 3. The bag is then completed for shipping
and storage. It is completely hermetically sealed preventing
moisture and foreign elements from coming into contact with the
contents or coming into the top to contact the rib and groove
elements. When the bag is to be used, the user grips the top to
tear the strip 17 therefrom in the manner shown in FIG. 4. The
weakened tear lines 13b and 14b insure that a strip of uniform
width will be torn from the top leaving flanges 17 and 18 intact.
This prevents the tear from turning downwardly to tear into the
profiles or from turning upwardly so that only a portion of the top
is removed. Thus, the plastic sheet 12 for the bag can be chosen
from material that is transparent, flexible and has all the
properties desirable in a barrier film. The material can also be
chosen of minimum weight to effect a saving in cost of material and
yet, at the top of the bag the light weight of the bag material
does not hamper the function of the interlocking elements or does
not hamper the capability of removing a tear strip for access to
the interlocking rib and groove elements.
In some instances it may be desired to provide a flat reinforcing
tear strip separate from the strips which support the rib and
groove elements, as shown in the structures of FIGS. 5 thru 9.
In FIG. 5 a bag body 20 is formed of plastic film and has fused to
the inner surface, profile strips 21 and 22 carrying shaped
complementary interlocking rib and groove profiles. Also fused to
the inner surface of the sheet material of the bag are reinforcing
strips 23 and 24 which have tear lines of weakened resistance 23a
and 24a extending down their center. Thus, when the bag is opened,
the top can be torn and the bag will readily separate along lines
23a and 24a. If the plastic film is relatively light in weight,
this will enhance the removal of the top strip.
It may be desired to form the profile strips 21 and 22, and the
reinforcing tear strips 23 and 24 of different materials. The
profile strips 21 and 22 will be of a stiff plastic having
characteristics necessary for optimum performance of the
interlocking rib and groove profiles. the reinforcing strips 23 and
24 will be of a tough material which resists lateral tearing and
encourages the tearing of the strips down through the center
tearlines 23a and 24a. The plastic of the reinforcing tear strips
may be only sufficiently thick to guide the tear for obtaining
economy in production. A plastic which has an oriented grain so
that it tears more easily in a longitudinal direction is
particularly well suited for this function.
When the tear strip is removed from the bag, in the manner shown in
FIG. 4, the lower portions of the reinforcing strip which remain,
i.e., in FIG. 5 the portions below the lines 23a and 24a, provide
reinforced gripping flanges. These remaining portions of the strips
reinforce the lips to aid the user in pulling apart the
interlocking rib and groove elements.
In another form, as shown in FIG. 7, the reinforcing film strips 28
and 29 are constructed so that the bag must tear between the strips
28 and 29 and the profile strips 26 and 27. The strips are fused to
the inside wall of the bag 25, and when the top is torn from the
bag, the tear will follow along the lines 25a and 25b of the bag
material itself.
In most instances it will be apparent to the user where to grip the
bag for tearing the strip from the top, but index markings or color
lines may be added to the plastic material to illustrate where the
tear is to be begun. Also, the strips such as 28 and 29 may be
colored so as to show up through the transparent bag to indicate to
the user where to grip. In addition an end notch may be provided
such as shown at 52 in FIG. 11 as will be later described
herein.
In the form illustrated in FIG. 8, reinforcing ribs are provided in
the reinforcing tear strip so as to guide the tear along said ribs.
In the bag 36 of FIG. 8, profile strips 37 and 38 are fused to the
inner surface. Reinforcing tear strips 39 and 40 are also fused to
the inner surface of the bag, above the profile strips. These
reinforcing strips 39 and 40 each have parallel ribs extending
along the surface such as shown at 39a and 39b for the strip 39,
and at 40a and 40b for the strip 40. The ribs are positioned so as
to be in alignment or immediately adjacent with each other in the
collapsed bag so that when the user grips the top of the bag, the
strips 39 and 40 will tear down the center between the ribs. The
ribs will prevent the line of tear from deviating sideways.
In the arrangement of FIG. 6, separate parallel reinforcing strips
are provided to compel the line of tear to travel between the
strips. In the bag 30, profile strips 31 and 32 are attached to the
inner surface. Above the profile strips of one side wall of the bag
are the reinforcing tear strips 33 and 34 and on the other side,
opposite them, are reinforcing tear strips 35 and 36. These strips
are in alignment so that the tear lines 30a and 30b are opposite
each other. When a user grips the top of the bag, the top portion
including the strips 33 and 35 will be removed from the bag
top.
In the structure of FIG. 9, the reinforcing tear strip 44 is formed
as a single strip. In this bag 41, rib and groove profile strips 42
and 43 are fused to the inner surface of the bag wall. The
reinforcing tear strip 44 is fused to the film above the profile
strips and has tear lines 45 and 46 of weakened tear resistance
positioned to be opposite each other so that the top portion of the
bag will be smoothly removed when it is gripped and torn.
FIG. 10 illustrates an arrangement wherein the profiles 48 and 49
are formed integral with the wall of a bag 47. Tear strips 50 and
51 are fused to the inner surface of the bag above the profiles and
have tear lines 50a and 51b. It will be understood that with each
of the arrangements shown in FIGS. 7 thru 9, the profiles may be
integral with the bag wall rather than being carried on strips
attached to the bag wall. The provision of strips carrying the
profiles permits the bag wall to be of thinner material.
In the arrangement of FIG. 10, an end notch 52 may be provided as
shown in FIG. 11. This end notch provides a starting point to help
insure that the tear will begin at the correct location. It will be
understood that the starting notch 52 may be utilized with each of
the structures shown in the drawings. The notch is preferably
formed by providing a small indentation or cut in the plastic
material and then sealing around the edges of the cut to reatin the
moisture and dust-proof integrity of the bag, or by making a broad
fin type seal and then cutting a notch into it.
In FIG. 12 a bag 55 has profile strips 56 and 57 fused to the inner
surface thereof. These profile strips have mating interlocking rib
and groove elements similar to the strips earlier described herein.
Above the profile strips are positioned reinforcing strips 58 and
59, which are fused to the material of the bag 55. The reinforcing
strip 58 has a tear line 58a extending therealong, and the strip 59
has a tear line 59a which is positioned to coincide with the tear
line 58a. Thus, when the top is torn off the bag, the two tear
lines 58a and 59a, being opposite each other, will permit removal
of a strip to release the flanges for separating the rib and groove
elements. To aid in guiding the tearing of the bag along the tear
lines, guiding ribs are positioned above and below the tear lines.
The strip 58a has ribs 58b and 58c. The strip 59 has ribs 59b and
59c. These ribs confine the direction of tear to a straight line
along the top, i.e., along the tear lines 58a and 59a.
In the arrangement of FIG. 13, a one-piece strip 61 is positioned
within a bag 60. This strip 61 carries the interlocking profiles
61a and 61b as well as the tear lines 61c and 61f. The tear lines
are opposite each other for permitting tearing off a strip from the
top of the bag. To guide the tear of the material along the tear
lines, ribs are positioned above and below the tear lines. Ribs 61d
and 61e are positioned on each side of the tear line 61c, and ribs
61g and 61h are positioned on each side of the tear line 61f. When
the top strip is torn off, the ribs 61e and 61h will remain with
the bag and provide additional gripping surfaces for grasping the
flanges and pulling them apart to separate the rib and groove
elements 61a and 61b.
In FIG. 14 a bag 70 is formed of plural layers 70a and 70b of
material. 70a, for example, may be thermoplastic bonded to an outer
layer 70b of paper or foil and various numbers and types of layers
may be employed which provide the physical properties required by a
bag for a particular use. Bonded to the inner layer of the bag are
rib and groove profile strips 73 and 74. Above the profile strips
are reinforcing strips 71 and 72 which are bonded to the inner
layer of the bag and have tear guide ribs, or other tear guide
means thereon.
The bag 70 is shown closed at the top with a seam 70c. It will be
understood that various forms of profile strips and reinforcing
strips shown and described with the other figures may be employed
with a multilayer bag, such as shown in FIG. 14, and the bags may
be seamed at the top for certain purposes, rather than being
continuous at the top. With the arrangement of FIG. 14, the
separate layers of the bag may each be of a material optimumly
suited to perform the function of giving the bag wall stiffness,
impermeability, transparency or opacity, or whatever physical
property that is required, and yet, the profile strips may be
formed of a plastic of optimum physical properties for the
interlocking rib and groove elements. Further, the reinforcing
strips may also be formed of a plastic or other material which has
optimum properties for functioning as a tear guide, stiffener and
flange strengthening means. Thus, by making the bag of multiple
components, a substantial saving can be effected while actually
enhancing the properties of the bag and its parts.
The profile strips and the tear strips of the various embodiments
are fused to the sheet material by a suitable fusing process. The
continuous sheet material and strips will conventionally be
provided from rolls with the strips being fused to the preprepared
sheet material. The strips may be fused immediately after they are
extruded, as described in the above copending applications, or may
be preformed and fused by the application of heat and pressure at a
later time. The sheet with the strips fused thereto then may be
wound upon a roll or in some instances, it may be desirable to form
the bag immediately by doubling over the sheet and forming the bag
as illustrated in FIG. 2.
While a bag is shown that has the top formed of continuous film
doubled over, in some instances separate sheets may be formed with
a seam formed at the very top of the bag above the reinforcing tear
strips. It will be understood that in the claims wherein reference
is made to a plastic film structure for forming a bag, the intent
is to cover the film structure in its condition in a sheet as shown
in FIG. 1 before being formed into a bag as well as after the film
structure is embodied in a bag in the condition shown in FIGS. 2
and 3, for example.
The bag material will preferably be transparent, though not
necessarily when made from barrier films, and in some instances,
the tear strips may be colored so that the user can readily see
where the tear is to be made. In the arrangement of FIG. 8, for
example, the material of the bag 36 may be transparent and the
strips 39 and 40 may also be transparent with the ribs 39a and 39b
and the ribs 40a and 40b being colored, or in FIG. 6 the strips 33
and 35 could be colored.
In the arrangement of FIG. 8, while the strips 39 and 40 may be
uniformly fused to the film, and the center portions of the strips
39 and 40 between the ribs may be sealed by a cross-weave
pattern.
While the reinforcing tear strips are shown in the drawings as
fused to the inner surface of the film sheet material of the bag,
in some instances it may be desired to laminate them to the outer
surface.
* * * * *