U.S. patent application number 10/849917 was filed with the patent office on 2004-12-02 for plastic bag for the vacuum preservation of food.
This patent application is currently assigned to NUOVA POLIVER DI ODDONE COLOMBA & C. S.n.c.. Invention is credited to Malaspina, Alberto.
Application Number | 20040240756 10/849917 |
Document ID | / |
Family ID | 33105054 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040240756 |
Kind Code |
A1 |
Malaspina, Alberto |
December 2, 2004 |
Plastic bag for the vacuum preservation of food
Abstract
A bag of plastic material for vacuum preservation of food
comprises two rectangular walls joined together along three sides.
The width of one of the walls is larger than the width of the other
wall by a predetermined quantity, preferably about 5%.
Inventors: |
Malaspina, Alberto; (Ovada,
IT) |
Correspondence
Address: |
MODIANO & ASSOCIATI
Via Meravigli, 16
MILANO
20123
IT
|
Assignee: |
NUOVA POLIVER DI ODDONE COLOMBA
& C. S.n.c.
|
Family ID: |
33105054 |
Appl. No.: |
10/849917 |
Filed: |
May 21, 2004 |
Current U.S.
Class: |
383/105 |
Current CPC
Class: |
B31B 70/10 20170801;
B65D 81/2023 20130101; B31B 2155/002 20170801; B31B 2155/00
20170801; B65D 31/00 20130101; B31B 2160/10 20170801; B31B 70/00
20170801 |
Class at
Publication: |
383/105 |
International
Class: |
B65D 033/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 27, 2003 |
IT |
TO2003U000089 |
Claims
What is claimed is:
1. A bag of plastic material for the vacuum preservation of
foodstuffs, comprising two rectangular walls joined together along
three sides, wherein the width of one of the walls is larger than
the width of the other wall by a predetermined quantity.
2. The bag of claim 1, wherein the quantity by which the width of
one wall exceeds the width of the other wall is in the range 2% to
10%.
3. The bag of claim 2, wherein said excess quantity is 5% of the
width of said other wall.
4. A process for mass-producing bags according claim 1, wherein two
superposed ribbons of plastic sheet are continuously fed along a
path and transverse welding bars are applied at intervals to the
ribbons to obtain welds joining the ribbons together to form
longitudinal sides of the bag, characterized in that one of the
ribbons is fed at a higher speed than the other ribbon.
5. A process for mass-producing bags according claim 1, wherein two
superposed ribbons of plastic sheets are continuously fed along a
path and longitudinal welding bars are applied to the opposite
edges of the ribbons to obtain welds joining the ribbons together
to form longitudinal sides of the bag, wherein a humped plate is
inserted between the ribbons.
Description
BACKGROUND OF THE INVENTION
[0001] This invention is concerned with a bag of plastic material
for the vacuum preservation of foodstuffs in home.
[0002] It is a widespread practice nowadays to pack vegetables,
meat, cheese and other foodstuffs in bags or envelopes for
protection and preservation, the bags being then stocked in
refrigerators. The bags comprise two walls of a plastic material,
welded together along three sides. The walls are usually
many-layered polyethylene sheets, which are compatible with food
but are impermeable to gas. In order to improve preservation of
certain quick-spoiling foodstuffs, it has recently become more
usual to evacuate the bag. Air is evacuated from the bag by means
of a vacuum pump or by other means, and the bag is then tightly
sealed at its mouth by hot-welding.
[0003] However, the internal bag surfaces in conventional bags are
liable to adhere locally to each other or to any smooth, wet
surface of the food, thereby giving rise to self-contained air
pockets which are not emptied during air extraction and therefore
remain in the sealed bag. In order to prevent the formation of such
air pockets, it has been proposed to provide one of the bag walls
with embossed blobs or projections or crests, in order to provide a
network of furrows or channels which will afford the air a path to
the bag mouth, where suction takes place.
[0004] EP-A 1 281 625 discloses a different device for preventing
the formation of air pockets, whereby the inside of one of the bag
walls is hot-printed with two or three rectilinear rough bands,
extending longitudinally over the entire length of the bag. The
bands are produced by applying a welding bar lined with teflon
against the sheet comprising the bag wall.
SUMMARY OF THE INVENTION
[0005] It is now the main object of the invention to provide a bag
of plastic material for vacuum preservation of foodstuffs, which
avoids the drawback of the trapped air pockets, and which, at the
same time, is cheaper to manufacture than bags with embossed or
rough walls, and which allows the bag to be manufactured cheaply on
conventional assembly lines, without a need for additional complex
machinery.
[0006] The above and other objects and advantages, such as will
appear from the following disclosure, are achieved by the invention
with a bag of plastic material having the features recited in claim
1, the dependent claims reciting other advantageous features.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] A preferred embodiment of the invention will now be
described, by way of non-limiting example, with reference to the
attached drawings, wherein:
[0008] FIG. 1 is a perspective view of a bag according to the
invention;
[0009] FIG. 2 is a front view of the inventive bag during air
extraction;
[0010] FIG. 3 is a diagrammatical side view of equipment for mass
manufacturing bags according to the invention;
[0011] FIG. 4 is a diagrammatical front view of an alternative
technique for mass manufacturing bags according to the
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0012] With reference to the Figures of the drawings, a bag 10
comprises two rectangular walls 12 and 14, which are joined
together along their edges on three sides 30, 32, 34 by welding.
Each wall, as known per se, is made of a many-layered plastic
material, comprising an inner polyamide layer, which imparts a good
mechanical resistance to the bag and also is an effective barrier
to the leaking of air, and sandwiched between two outer layers of
polyethylene, a material that is food-compatible and is easily
weldable.
[0013] According to the invention, the width of wall 12 across the
side welds 30, 34 exceeds the width L of wall 14 by a quantity in
the range 2% to 10%, preferably 5%. Consequently, wall 12 is slack
with respect to wall 14 in the transverse direction, so that it
will show undulations when wall 14 is distended.
[0014] As shown on FIG. 2, during the evacuation of air, when the
opposite walls are squeezed between the lips of the extractor near
the mouth of the bag (not shown), passages are created, such as 18,
in a substantially longitudinal direction and with random
distribution, the passages providing exit paths for the air.
[0015] The slack wall of the bag will of course be crumpled into
small folds at the transverse weld 32 along the bottom of the bag,
and in order to insure that a dependable, air-tight weld is
obtained, the weld will preferably be made wider than the
longitudinal welds 30, 34. This will improve the sealing at spots
where leak passages might develop along the joining line between
the flat surface of wall 14 and the wavy surface of wall 12.
[0016] A known system for manufacturing conventional bags
comprises, as shown on FIG. 3, two reels 20, 22, from which
respective ribbons 24, 26 are unrolled to form the walls of the
bag. Transverse welds 28 are made at predetermined intervals along
the ribbons by means of welding bars B1, B2, in order to define the
side borders of the bag, and longitudinal welds are also made on
one of the edges of the ribbon to define the bottom of the bag. In
order to have one slack wall, ribbon 24 is pulled at a speed V1
slightly in excess of the speed V2 of ribbon 26, so that excess
material is fed forward between successive welds.
[0017] According to an alternative technique for the manufacture of
bags, the sides of the bag are defined by longitudinal welds 130,
132, made along the edges 124, 126 of the ribbons as they unroll
from the reels (not shown), and the bottom of the bag is made by
transverse, spaced welds. In this case, as shown on FIG. 4, the
slackness in one of the walls is obtained by interposing a humped
plate 134 between the ribbons.
[0018] The bag according to the invention can be manufactured by
making only minor modifications to conventional bag manufacturing
equipment.
[0019] As a further advantage of the invention, the bag has the
same degree of pliability of a conventional bag, so that it can
easily match the changing shapes of the contents.
[0020] A preferred embodiment of the invention has been described,
but modifications can of course be made to it by a person skilled
in the art within the scope of the same inventive concept. By way
of example, both walls might be integral with each other along one
of the longitudinal edges, with welds made only on the other side
and along the bottom.
[0021] The disclosures in Italian Utility Model Application No.
TO2003U000089 from which this application claims priority are
incorporated herein by reference.
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