U.S. patent application number 09/854768 was filed with the patent office on 2001-12-13 for heat-insulating container.
This patent application is currently assigned to Fuji Seal, Inc.. Invention is credited to Imai, Hiroyuki, Namba, Toshiyuki, Ohi, Akira.
Application Number | 20010050287 09/854768 |
Document ID | / |
Family ID | 26591870 |
Filed Date | 2001-12-13 |
United States Patent
Application |
20010050287 |
Kind Code |
A1 |
Namba, Toshiyuki ; et
al. |
December 13, 2001 |
Heat-insulating container
Abstract
A heat-insulating food container includes an injection-molded
container body having a bottom wall, a circumferential wall
integrally connected to a periphery of the bottom wall and upwardly
extending therefrom for defining an inner space and an upper open
end, and vertical ribs vertically extending along the
circumferential wall. The circumferential wall includes
circumferential wall parts respectively having different diameters
and arranged in such a manner as to form the circumferential wall
with the diameter thereof decreasing in a stepwise manner as it
advances downwardly, thereby forming corresponding stepped portions
on an exterior surface and an interior surface thereof.
Inventors: |
Namba, Toshiyuki; (Osaka,
JP) ; Ohi, Akira; (Osaka, JP) ; Imai,
Hiroyuki; (Osaka, JP) |
Correspondence
Address: |
Jordan and Hamburg
122 East 42nd Street
New York
NY
10168
US
|
Assignee: |
Fuji Seal, Inc.
|
Family ID: |
26591870 |
Appl. No.: |
09/854768 |
Filed: |
May 14, 2001 |
Current U.S.
Class: |
220/592.17 ;
220/646; 220/651 |
Current CPC
Class: |
B65D 81/3865 20130101;
B65D 1/265 20130101 |
Class at
Publication: |
220/592.17 ;
220/646; 220/651 |
International
Class: |
B65D 083/72; B65D
001/42 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2000 |
JP |
2000-141365 |
Jul 3, 2000 |
JP |
2000-200998 |
Claims
What is claimed is:
1. A heat-insulating food container comprising an injection-molded
container body having a bottom wall, a circumferential wall
integrally coupled to a periphery of the bottom wall and upwardly
extending therefrom for defining an inner space and an upper open
end, and vertical ribs vertically extending along said
circumferential wall, said circumferential wall including
circumferential wall parts respectively having different diameters
and arranged in series in such a manner as to form said
circumferential wall with the diameter thereof decreasing in a
stepwise manner as it advances downwardly, thereby forming
corresponding stepped portions on an exterior surface and an
interior surface thereof.
2. A heat-insulating food container according to claim 1 further
comprising a downwardly-facing subsidiary rib extending along the
circumferential wall in the circumferential direction thereof with
a predetermined clearance with respect to said circumferential
wall.
3. A heat-insulating food container according to claim 1 further
comprising a plurality of downwardly-facing subsidiary rib s each
respectively extending along the circumferential wall in the
circumferential direction thereof at a different height with a
predetermined clearance with respect to said circumferential
wall.
4. A heat-insulating food container comprising an injection-molded
container body having a bottom wall, a circumferential wall
integrally coupled to a periphery of the bottom wall and upwardly
extending therefrom for defining an inner space and an upper open
end, vertical ribs vertically extending along said circumferential
wall, and at least one downwardly-facing subsidiary rib extending
along said circumferential wall in a circumferential direction
thereof to have a double layered annular portion with a
predetermined clearance between the circumferential wall and said
at least one downwardly-facing subsidiary rib, and each portion of
said at least one downwardly-facing subsidiary rib between adjacent
ones of said vertical ribs having laterally opposite edges being
coupled to said adjacent ones of said vertical ribs.
5. A heat-insulating food container comprising an injection-molded
container body having a bottom wall, a circumferential wall
integrally coupled to a periphery of the bottom wall and upwardly
extending therefrom for defining an inner space and an upper open
end, vertical ribs vertically extending along said circumferential
wall, a flange formed around said upper open end of the container
body, said container body having an annular stepped portion near
the upper open end of the interior surface, said stepped portion
serving as an indication line for indicating a suitable limit of
hot water or the like poured into the container body, and a
reinforcing means formed on said circumferential wall below said
indication line and above a middle portion between the bottom wall
and the open end for reinforcing said container body by providing a
stepped portion on said circumferential wall.
6. A heat-insulating food container according to claim 5, wherein
said circumferential wall is formed in a stepwise manner to have a
stepped portion serving as said reinforcing means.
7. A heat-insulating food container according to claim 5, wherein
said circumferential wall includes an upper circumferential wall
part and a lower circumferential wall part, both of which are
coupled together in a stepwise manner via an annular coupling part
having a horizontal surface, a downwardly-facing subsidiary rib
extending along a lower periphery of said upper circumferential
wall part with a predetermined clearance with respect to the lower
circumferential wall part, and with laterally opposite edges of
each portion of said downwardly-facing subsidiary rib between
adjacent ones of said vertical ribs being coupled to said adjacent
ones of the vertical ribs, wherein said coupling part and said
subsidiary strip together constitute said reinforcing means.
8. A heat-insulating food container according to claim 5, wherein
said reinforcing means positioned at a height of up to 50 to 70%
from the bottom wall to the upper open end.
9. A heat-insulating food container comprising an injection-molded
container body having a bottom wall, a circumferential wall
integrally coupled to a periphery of the bottom wall and upwardly
extending therefrom for defining an inner space and an upper open
end, and vertical ribs vertically extending along said
circumferential wall, wherein the width (T) of a base part of each
vertical rib and the thickness (t) of the circumferential wall are
formed based upon the relationship of t.ltoreq.T.ltoreq.4t.
10. A heat-insulating food container according to claim 9, wherein
said injection-molded container body is made of a polypropylene
resin having a melt index (MI) of 50 to 100, and has a wall
thickness (t) of 0.2 mm to 0.6 mm.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a heat-insulating container
that is suitable for containing therein instant noodles or any
other food blocks that can be served after pouring hot water
therein, or containing therein a low-temperature food such as a
deep-frozen or chilled food block.
[0003] 2. Discussion of the Background
[0004] In order to place instant noodles such as dried noodles,
snack noodles, miso-soup, or hot coffee or cold beverage in a
container, some specific structures are employed to provide
heat-insulating capability to the container, thereby providing
consumers with protection against burns, or ease hand grasping.
[0005] An expanded polystyrene foam or any other types of synthetic
resin foam, or injection-molding technique are employed to provide
such a heat-insulating container, among which an injection-molded
container made of polypropylene is frequently used due to a current
social demand to an environmentally benign material. An
injection-molded container body of the container is provided with
ribs extending vertically along the circumferential wall to prevent
heat of hot water poured in the container from transmitting to the
fingers of the user grasping the container.
[0006] The heat-insulating container of the above type must be
light-weight and low-cost. To achieve these, the container may be
formed with a thinner wall, thereby reducing the amount of a resin
material used. However, the thinner wall of the container poses a
problem of deteriorating the strength of the container body.
Particularly, when in contact with hot water, the container itself
is softened and easy to deform, resulting in the deterioration in
strength of the body.
[0007] Accordingly, it is an object of the present invention to
provide a heat-insulating container that has an excellent
heat-insulating capability and a relatively high strength
structure, as well as a light-weight structure.
SUMMARY OF THE INVENTION
[0008] According to the present invention, there is provided a
heat-insulating food container including an injection-molded
container body having a bottom wall, a circumferential wall
integrally coupled to a periphery of the bottom wall and upwardly
extending therefrom for defining an inner space and an upper open
end, and vertical ribs vertically extending along the
circumferential wall. The circumferential wall includes
circumferential wall parts respectively having different diameters
and arranged in such a manner as to form the circumferential wall
with the diameter thereof decreasing in a stepwise manner as it
advances downwardly, thereby forming corresponding stepped portions
on an exterior surface and an interior surface thereof
[0009] With the above arrangement, the container has an excellent
heat-insulating capability and a relatively high strength
structure. The container with the stepped portion can be made by a
relatively small amount of a resin material, resulting in reduced
material costs and light-weight structure, in comparison with the
container provided with a thicker wall portion for obtaining a
sufficient strength.
[0010] There may be provided a downwardly-facing subsidiary rib
extending along the circumferential wall in the circumferential
direction thereof with a predetermined clearance with respect to
the circumferential wall. The thus arranged downwardly-facing
subsidiary rib makes a double-layered structure in cooperation with
the circumferential wall, so that the container body may be
strengthened. In addition, the clearance defined between the
downwardly-facing subsidiary rib and the circumferential wall
prevents heat caused by hot water poured into the container body
from straightly transmitting to the subsidiary rib. Thus, the user
can easily grasp the container body with his or her fingers via the
subsidiary rib.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above, and other objects, features and advantages of the
present invention will become apparent from the detailed
description thereof in conjunction with the accompanying drawings
wherein.
[0012] FIG. 1 illustrates a container according to a first
embodiment of the present invention with a half part thereof in
section.
[0013] FIG. 2 is a cross section of an essential portion of the
container of FIG. 1.
[0014] FIG. 3 illustrates the containers stacked on each other with
half parts thereof in section.
[0015] FIG. 4 illustrates a container according to a second
embodiment of the present invention with a half part thereof in
section.
[0016] FIG. 5 illustrates a container according to a third
embodiment of the present invention with a half part thereof in
section.
[0017] FIG. 6A is a sectional plan view of an essential portion of
the container, illustrating a vertical rib.
[0018] FIG. 6B is a sectional bottom view of an essential portion
of the container, illustrating a bottom wall of the container
body.
[0019] FIG. 7 illustrates a container according to a fourth
embodiment of the present invention with a half part thereof in
section.
[0020] FIG. 8 is a sectional plan view of an essential portion of
the container, illustrating a vertical rib.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Embodiments of the present invention will hereinafter be
described with reference to the accompanying drawings. A container
according to the first embodiment of the present invention in FIGS.
1 to 3 is illustrated as that for containing therein an instant or
dried noodle block.
[0022] A container 1 includes a heat resistant container body 3
made of a plastic material such as polypropylene or high-density
polyethylene. It has a bottom wall and a circumferential wall 3a
integrally coupled to a periphery of the bottom wall and extending
upwardly therefrom for defining an interior space and an upper open
end. The container body 3 has a flange 2 around the upper open end,
which has a reverse U-shaped cross section. The upper open end of
the container body 3 is detachably sealed by a sealing lid (not
shown) formed by an aluminum foil layer and a laminate layer such
as a synthetic resin film or paper.
[0023] The container body 3 is formed by the injection-molding to
have its diameter decreasing as it advances towards the lower side.
The circumferential wall 3a of the container body 3 is also
provided with vertical ribs 7 vertically and continuously extending
along the exterior surface of the circumferential wall 3a. The
container body 3 has an upper part or larger-diameter part 5 which
has a flat surface with no concave or convex area and is formed in
a cylindrical shape. The vertical ribs 7 terminate at their upper
ends in the larger-diameter part 5 and have surfaces flush with a
surface 5a of the larger-diameter part 5.
[0024] The circumferential wall 3a of the container body 3 forms
corresponding stepped portion respectively on an interior surface
and an exterior surface thereof Specifically, the circumferential
wall 3a includes a plurality of cylindrical parts integrally
coupled to each other in stepwise manner. In this embodiment, two
cylindrical parts, namely an upper circumferential wall part 9a and
a lower circumferential wall part 9b are formed.
[0025] The upper circumferential wall part 9a includes a flared
part 11a having a smaller diameter than the larger-diameter part 5
and coupled to the same via a first coupling part 13 in the form of
an annular horizontal wall, and a straight part 11b with a
substantially uniform diameter extending downwardly from a lower
periphery of the flared part 11b. The straight part 11b has its
lower periphery coupled to the upper periphery of the lower
circumferential wall part 9b via a second coupling part 10 in the
form of an annular horizontal wall. The upper surface of the
annular horizontal wall of the first coupling part 13 is provided
near the upper open end of the container body 3 to act as an
indication line 13a indicating a suitable level of hot water poured
in the container body 3 for reconstituting the dried food. The
straight part 11b has a lower periphery, along which a
downwardly-facing subsidiary rib 14 extends with a clearance 22
defined with respect to the lower circumferential wall part 9b and
having each portion thereof between adjacent ones of the vertical
ribs 7 having laterally opposite ends respectively coupled to those
adjacent vertical ribs 7. The subsidiary rib 14 acts as a
reinforcing means in cooperation with the second coupling part 10
for reinforcing the container body 3 against the grasping force of
the user and has a lower periphery positioned below the indication
line 13a but above the middle portion of the container body 3
between a bottom wall 3b and the upper open end. The reinforcing
means is preferably positioned at a height of up to 50 to 70% from
the bottom wall 3b to the upper open end. The vertical ribs 7
project than the subsidiary rib 14, and slant at the same slanting
angle as the lower circumferential wall part 9b to extend
substantially in parallel relationship with the same. The
downwardly-facing subsidiary rib 14 preferably extends through all
the vertical ribs 7. However, the subsidiary rib 14 is not
necessarily limited to this. It is possible to partially omit the
subsidiary rib 14 at a portion or portions between predetermined
adjacent vertical ribs.
[0026] A holding rib 15 is formed on the inner circumferential
surface of the lower circumferential wall part 9b and below the
reinforcing means, which extends in the circumferential direction
to hold thereon the vertical ribs 7 or the like of another
container stacked on the container 1, as illustrated in FIG. 3. A
cylindrical leg part 17 is integrally coupled to a lower surface of
the bottom wall 3b.
[0027] A tubular label 18 having a heat-shrinkable characteristic
is applied on the circumference wall 3a. The label 18 has an
inwardly facing surface applied thereon with a heat-sensitive
bonding agent that is activated by heat at the time of
heat-shrinkage of the label 18 to possess adhesive power. The upper
circumferential wall part of the label 18 is bonded to a surface 5a
of the larger-diameter part 5 of the container body 3 via the
heat-sensitive bonding agent. Accordingly, the label 18, which has
a flared shape along the vertical ribs 7, is unlikely to slip
downwardly away from the container body 3, and can therefore be
held in place. Thus, the label 18 provides printed information with
good appearance.
[0028] According to the above arrangement, hot water poured in the
container 1 heats the circumferential wall 3a which provides a
grasping portion of the container body 3 to the user. However, the
vertical ribs 7 together act as radiation means of radiating heat
transmitting from the circumferential wall 3a so that the radially
outer ends or ridge parts of the vertical ribs 7 are heated only to
a relatively low temperature, and provide only a small contact area
with the fingers of the user. As a result, the user is unlikely to
excessively feel hot via his or her fingers grasping the container
1.
[0029] As an additional advantage according to this embodiment of
the present invention, even with a relatively strong grasping
force, the container body 3 is unlikely to be deformed because of
the reinforcing means. The reinforcing means is made up by the
second coupling part 10 and the subsidiary rib 14, and formed
around the circumferential wall 3a at a middle height of the
container body 3, which is a easily deformable part of the
container body 3, so that it can provide an improved strength
against the force effecting in the diametrical direction as
compared with the container having a circumferential wall 3a formed
with a flat surface.
[0030] A commonly used plastic material, from which the container
body 3, the subsidiary rib 14, and the like of the container are
formed in this embodiment, may be softened and decrease in
stiffness with heat, thereby causing the likelihood of
deteriorating the strength of the container body 3. However, the
radially outwardly positioned vertical ribs 7 than the subsidiary
rib 14 is unlikely to be heated to a high temperature, thereby
preventing deterioration in strength of the vertical ribs 7, even
if the subsidiary rib 14 along with the container body 3 is heated.
The flange 2, which is kept out of direct contact with the hot
water is positioned above the indication line 13a, enables the
container body 3 to maintain its stiffness even if the hot water is
placed therein.
[0031] The circumferential wall 3a of the container body 3 also has
stepped portions on an interior surface and an exterior surface
formed correspondingly to each other. This surface formation
contributes to the decrease in thickness of the circumferential
wall 3a of the container body 3 without the necessity of providing
a thicker portion for reinforcing the container body. Thus, the
amount of the synthetic resin material used can be reduced,
resulting in reduced material costs and light-weight structure.
[0032] As described above, the container body 3 has the vertical
ribs 7 extending in slanting relationship with the vertical axis of
the container body 3 and the circumferential wall 3a extending in
parallel or slanting relationship with the vertical axis of the
container body 3, and the subsidiary rib 14 solely provided on the
container body 3. The container body 3 having this outer
configuration thus has a substantially trapezoidal shape with the
bottom side having a smaller diameter, which enables the container
body 3 to be easily pulled out from a die in a direction towards
the smaller diameter side of the container body 3. The sole
arrangement of the subsidiary rib 14 is unlikely to deteriorate
smooth removing operation, and also provides a limited number of
stepped portions on the interior surface of the container body 3 to
prevent a fork,, chopsticks or the like from easily getting caught
on such portions, while assuring the necessary strength.
[0033] FIG. 4 illustrates the container according to the second
embodiment of the present invention, whose container body 3
includes the circumferential wall 3a made up by the upper
circumferential wall part 9a and the lower circumferential wall
part 9b in the same manner as the first embodiment. The flange 2 is
formed solely by the horizontal wall. The larger-diameter part 5
has the lower periphery, along which a downwardly-facing subsidiary
rib extends with a predetermined clearance 22 with respect to the
flared part 11a of the upper circumferential wall part 9a and has
each portion thereof between the adjacent vertical ribs 7 with
laterally opposite edges of each portion respectively coupled to
these adjacent vertical ribs 7. The subsidiary rib 14a is
positioned at a height equal to or closer to the indication line
13a, so that the relatively flat flange 2 can have substantially
the same strength as the flange having a reverse U-shaped cross
section. Through the flattening of the flange 2, the lid covering
the opening of the container body 3 can have an improved
productivity for obtaining a sufficient sealing ability, while the
flange 2 can have a reduced width. Also, in this embodiment, the
heat-shrinkable label 18 can be applied on the container body 3 in
the same manner as the first embodiment.
[0034] FIGS. 5 and 6 illustrate a container according to the third
embodiment of the present invention. The container of this
embodiment is also used to contain therein an instant or dried
noodle block as an example of dried foods.
[0035] The container 1 includes the cup-shaped container body 3
with the bottom wall. The container body 3 may be made of, for
example, polypropylene, high-density polyethylene, polystyrene or
any other types of plastic materials, as far as they each have a
proper heat-insulating characteristic and heat-resisting
characteristic suitable for a food container. Particularly, when
using a polypropylene resin such as a propylene-ethylene copolymer,
it preferably has a melt index (MI) of 50 to 100, and more
preferably 60 to 80.
[0036] The upper open end of the container body 3 is provided with
the flange 2, and is detachably sealed by a sealing lid (not shown)
formed by an aluminum foil layer and a laminate layer such as a
synthetic resin film or paper.
[0037] The container body 3 is formed by the injection-molding to
have its diameter decreasing as it advances towards the lower side.
The circumferential wall 3a of the container body 3 is also
provided with the vertical ribs 7 vertically and continuously
extending along the exterior surface of the circumferential wall
3a. The container body 3 has the upper part or larger-diameter part
5 which has a flat surface with no concave or convex area and is
formed in a cylindrical shape. The vertical ribs 7 terminate at
their upper ends in the larger-diameter part 5.
[0038] The vertical ribs 7 each are formed into a triangular shape
or trapezoidal shape with its width narrowing as it advances
towards a radially outer end or top part thereof, and are formed so
that the width T of the base part of each vertical rib 7 and the
thickness t of the circumferential wall 3a of the container body 3
can satisfy the relationship of t.ltoreq.T.ltoreq.4t. Where the
container is an instant food container with the bottom wall 3b
whose diameter is 50 to 80 mm and a height of 70 to 130 mm, an
applicable thickness t of the circumferential wall 3a of the
container body 3 is between the lower limit of 0.2 mm, less than
which a practical strength cannot be obtained, and the upper limit
of 1.0 mm, less than which short shot was conventionally easy to
occur during the injection molding. Particularly, it is preferable
to use a polypropylene resin with MI of 50 to 100, because the
container 1 having a thinner wall thickness, namely t of 0.2 mm to
0.6 mm can be manufactured.
[0039] Where the width T of the base part of each vertical rib 7 is
smaller than the thickness t of the circumferential wall 3a of the
container body 3, flowing passages of the resin used are not formed
so that the vertical ribs 7 cannot respectively act as grooves.
Accordingly, the molten resin are hard to sufficiently flow along
any vertical ribs, so that short shot may easy to occur. Where the
width T of the base part of each vertical rib 7 is larger than 4t,
the resistance force of the molten resin against the vertical ribs
is reduced. This enhances the flow of the molten resin to the
vertical ribs 7, but causes insufficient flow of the molten resin
into thinner parts between the adjacent vertical ribs 7 on the
circumferential wall 3a, which may result in uneven wall thickness
of the container body 3 and a higher likelihood of short shot
during the injection molding.
[0040] On the circumferential wall 3a of the container body 3
between the vertical ribs 7 are successively formed several
circumferential wall parts (three circumferential wall parts 9a, 9b
and 9c in this embodiment) defining stepped portions.
[0041] The circumferential wall parts 9a, 9b and 9c are
respectively coupled to the adjacent wall parts via corresponding
coupling parts 10. The downwardly-facing subsidiary rib 14a extends
along the lower periphery of the upper circumferential wall part 9a
with a predetermined clearance 22 with respect to the middle
circumferential wall part 9b, and is formed in the circumferential
direction of the container body 3 with each portion between the
adjacent vertical ribs 7 having laterally opposite ends
respectively coupled to these adjacent vertical ribs 7. A
subsidiary rib 14c also extends along the lower periphery of the
middle circumferential wall part 9b.
[0042] The vertical ribs 7 project than the subsidiary ribs 14b and
14c, and slant at the same slanting angle as the lower
circumferential wall part 9b to extend substantially in parallel
relationship therewith. In order to enhance the heat-insulating
characteristic of the container and reduce the material costs, the
height H of each vertical rib 7 with respect to the lower
circumferential wall part 9c is preferably in the range of 0.5
mm.ltoreq.H.ltoreq.5 mm, and more preferably in the range of 1.5
mm.ltoreq.H.ltoreq.4 mm.
[0043] Likewise to the first embodiment, the cylindrical leg part
17 is provided on the lower portion of the container body 3, and
the tubular label 18 having a heat-shrinkability is applied on the
circumferential wall 3a.
[0044] The container having the above arrangement is manufactured
by the injection molding, using a core die having a shape
corresponding to the interior surface of the container body 3 and a
cavity die having a shape corresponding to the exterior surface of
the container body 3. The cavity die forms an injection port at a
position corresponding to the center of the bottom wall of the
container body 3.
[0045] After putting the core die and the cavity die together, the
molten resin is poured under pressure through the injection port to
form the circumferential wall 3a along with numbers of the vertical
ribs 7. Since the molten resin flows at a high pressure, the
container body 3 is formed in a moment (e.g., about 0.5 to 1 sec.).
In this respect, the width T of the base part of each vertical rib
7 and the thickness t of the circumferential wall 3a of the
container body 3 are set based upon the relationship of
t.ltoreq.T.ltoreq.4t, so that the molten resin can smoothly flow
into distal ends of the circumferential wall part and the vertical
rib parts defined within the cavity. Thus, the container body 3
having a thinner wall can be manufactured with a high
formability.
[0046] For inject-molding the container for the instant food having
the bottom wall 3b of 50 to 80 mm in diameter, the container body 3
of 70 to 130 mm in height, the following conditions are
applied:
[0047] Injection pressure: 100 to 200 Mpa
[0048] Resin temperature (at the time of the injection): 200 to
280.degree. C.
[0049] Die temperature: 10 to 20.degree. C.
[0050] Even if the circumferential wall 3a providing a grasping
portion to the user is heated by such as hot water placed in the
heat-insulating container, the vertical ribs produce radiation
effect limiting the temperature increase of the ridge parts of the
vertical ribs, and provide relatively small contact area with the
fingers of the user. As a result, the user can easily grasp the
container without feeling the holder portion heated to a relatively
high temperature.
[0051] Also, even if the container body 3 is held with a relatively
large grasping force, the vertical ribs 7 radially projecting from
the container body 3 provides an improved strength against the
grasping force effecting in the diametrical direction in comparison
with the circumferential wall 3a having a flat surface, so that the
container body is unlikely to be deformed with such a grasping
force. It is common that synthetic resin is somewhat softened and
hence reduces its stiffness with heat. However, the subsidiary ribs
14b and 14c are unlikely to be heated with hot water or contents,
thereby preventing the deteriorated stiffness of the container body
3.
[0052] FIGS. 7 and 8 illustrate the container according to the
fourth embodiment of the present invention, in which corresponding
or identical parts to those of the second embodiment have been
given the same reference characters to omit a detailed description
thereof. The difference between this embodiment and the second
embodiment lies in that the container body 3 of this embodiment is
not provided with a stepped portion, and therefor has the ridge
parts of the vertical ribs 7 extending in parallel relationship
with the surface of the circumferential wall 3a of the container
body 3 throughout the length of the vertical ribs 7. In this case,
the height H of the vertical ribs 7 is preferably set in the range
of 1.5 to 4.0 mm.
Testing Examples
[0053] The testing was conducted to determine the formability for
the respective containers of the third and fourth embodiments. Test
results will be discussed below.
[0054] Under the injection-molding conditions shown in Table 1, the
heat-insulating container of the third embodiment was formed by
using a propylene-ethylene copolymer having an MI of 80, in which
the thickness t of the circumferential wall was 0.25 mm, the width
T of the base part of each vertical rib 7 was 0.7 mm, and the
height H of each vertical rib 7 was 1.5 mm at a lowest portion and
3.5 mm at a highest portion (Example 1).
[0055] Also, under the injection-molding conditions shown in Table
1, the heat-insulating container of the fourth embodiment was
formed by using a propylene-ethylene copolymer having an MI of 60,
in which the thickness t of the circumferential wall was 0.5 mm,
the width T of the base part of each vertical rib 7 was 0.8 mm, and
the height H of each vertical rib 7 was 1.9 mm (Example 2).
[0056] As a comparative example, the heat-insulating container
which was formed in the same manner as the Example 2, except that
the width T of the base part of each vertical rib 7 was 0.4 mm, was
prepared.
1 TABLE 1 Resin Injection Cycle time Number of temperature
(.degree. C.) pressure (Pa) (sec.) dies used Example 1 260 137.2M
9.2 2 Example 2 250 156.8M 9.1 6
[0057] To determine the formability in each example, the occurrence
of short shot near the upper open end of each container was
visually observed through insufficiently formed portion of the
container. A container on which no short shot was observed, was
determined as being made with a good formability. No short shot was
observed in the Examples 1 and 2, which were therefore determined
as being formed with a good formability. On the other hand, short
shot was observed in the Comparative Example, which was therefore
determined as being formed with a poor formability.
[0058] It is to be noted that the present invention is not limited
to the first to fourth embodiments as described above. For example,
a container of the present invention can be used for containing
therein not only dried noodles to be cooked with hot water but also
hot coffee or cold drink. The shape of the container body 3 is also
not limited to a circular shape in plan. Rather, it may have any
shape such as rectangular or elliptical shape.
[0059] This specification is by no means intended to restrict the
present invention to the preferred embodiments set forth therein.
Various modifications to the heat-insulating container of the
present invention, as described herein, may be made by those
skilled in the art without departing from the spirit and scope of
the present invention as defined in the appended claims.
* * * * *