U.S. patent application number 11/720599 was filed with the patent office on 2008-08-14 for heat insulated container.
This patent application is currently assigned to THERMOS K.K.. Invention is credited to Takafumi Fujii, Yu Kobayashi.
Application Number | 20080190942 11/720599 |
Document ID | / |
Family ID | 37053012 |
Filed Date | 2008-08-14 |
United States Patent
Application |
20080190942 |
Kind Code |
A1 |
Fujii; Takafumi ; et
al. |
August 14, 2008 |
Heat Insulated Container
Abstract
A heat insulated container, in which the presence of this heat
insulation performance can be confirmed from the outward
appearance. In a heat insulated container formed by coating a
radiation preventing film on at least one surface of an external
surface of an internal glass container and an internal surface of
an external glass container, disposing the internal container
inside the external container with a gap provided therebetween,
joining the internal container and the external container, and
evacuating the gap to a vacuum and sealing it, an average particle
diameter of particles on the surface of the radiation preventing
film is made a predetermined value or more. According to the heat
insulated container, since the average particle diameter of the
particles on the surface of the radiation preventing film is a
predetermined value or more, sufficient heat retaining performance
can be obtained.
Inventors: |
Fujii; Takafumi; (Niigata,
JP) ; Kobayashi; Yu; (Niigata, JP) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770, Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
THERMOS K.K.
Tsubame-shi
JP
|
Family ID: |
37053012 |
Appl. No.: |
11/720599 |
Filed: |
March 28, 2005 |
PCT Filed: |
March 28, 2005 |
PCT NO: |
PCT/JP05/05778 |
371 Date: |
May 31, 2007 |
Current U.S.
Class: |
220/592.27 ;
215/12.2 |
Current CPC
Class: |
A47J 41/0077
20130101 |
Class at
Publication: |
220/592.27 ;
215/12.2 |
International
Class: |
B65D 81/38 20060101
B65D081/38; B65D 23/08 20060101 B65D023/08 |
Claims
1. A heat insulated container formed by coating a radiation
preventing film on at least one surface of an external surface of
an internal glass container and an internal surface of an external
glass container, disposing said internal container inside said
external container with a gap provided therebetween, joining an
opening area of said internal container with an opening area of
said external container, and evacuating said gap to a vacuum and
sealing it, wherein said heat insulated container is formed such
that an average particle diameter of particles on the surface of
said radiation preventing film is a predetermined value or more,
and heat insulation performance can be evaluated from said particle
diameter.
2. A heat insulated container formed by coating a radiation
preventing film on at least one surface of an external surface of
an internal glass container and an internal surface of an external
glass container, disposing said internal container inside said
external container with a gap provided therebetween, joining an
opening area of said internal container with an opening area of
said external container, and evacuating said gap to a vacuum and
sealing it, wherein said heat insulated container is formed such
that an average particle diameter of particles on the surface of
said radiation preventing film on a part present in at least a side
portion of said heat insulated container is a predetermined value
or more, and heat insulation performance can be evaluated from said
particle diameter.
3. A heat insulated container according to claim 1 wherein said
predetermined value is 50 nm.
4. A heat insulated container according to claim 1, wherein a film
thickness of said radiation preventing film is 150 nm or more.
5. A heat insulated container according to claim 1, wherein said
radiation preventing film is an ITO film.
6. A heat insulated container formed by coating a radiation
preventing film on at least one surface of an external surface of
an internal glass container and an internal surface of an external
glass container, disposing said internal container inside said
external container with a gap provided therebetween, joining an
opening area of said internal container with an opening area of
said external container, and evacuating said gap to a vacuum and
sealing it, wherein an average particle diameter (x) of particles
on the surface of said radiation preventing film, and a film
thickness (y) thereof, have a relationship: y=4.4 x -43, where x is
between 50 nm and 200 nm.
7. A heat insulated container formed by coating a radiation
preventing film on at least one surface of an external surface of
an internal glass container and an internal surface of an external
glass container, disposing said internal container inside said
external container with a gap provided therebetween, joining an
opening area of said internal container with an opening area of
said external container, and evacuating said gap to a vacuum and
sealing it, wherein an average particle diameter (x) of particles
on the surface of said radiation preventing film on a part present
in at least a side portion of said heat insulated container, and a
film thickness (y) thereof, have a relationship: y=4.4 x-43, where
x is between 50 nm and 200 nm.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a U.S. national phase application under 35 U.S.C.
.sctn.371 of International Patent Application No.
PCT/JP2005/005778, filed Mar. 28, 2005. The International
Application was published in Japanese on Oct. 5, 2006 as
International Publication No. WO 2006/103739 A1 under PCT Article
21(2), the content of which are incorporated herein in its
entirety.
TECHNICAL FIELD
[0002] The present invention relates to a heat insulated container,
and more specifically, relates to a glass heat insulated container
formed by uniting an internal container with an external container
and evacuating a gap provided between the internal container and
the external container to a vacuum.
BACKGROUND ART
[0003] Conventionally, a glass heat insulated container is produced
by disposing a glass internal container inside a glass external
container with a constant gap provided therebetween, melting the
vicinity of the opening area to thereby integrally unite the
internal container with the external container, and evacuating the
gap to a vacuum to thereby provide a vacuum insulating layer.
Moreover an external surface of the internal container is coated
with a radiation preventing film such as an ITO film (a substance
produced by doping indium (In) oxide with tin (Sn)) so as to
decrease movement of heat between the inside and outside of the
heat insulated container, and this coating is carried out by means
of sputtering, CVD, PVD, and the like (for example, refer to
Japanese Unexamined Patent Publication No. 2003-299582).
SUMMARY OF THE INVENTION
[0004] However, even when coating of this radiation preventing film
is carried out using the same device, the heat retaining
performance of the radiation preventing film can vary. For example,
when coating of the radiation preventing film is carried out by
means of sputtering, even if the other conditions of sputtering are
exactly the same, the heat retaining performance of the radiation
preventing film can differ before and after replacing targets in
some cases.
[0005] It is considered that this heat retaining performance is
related to the thickness of the radiation preventing film. However,
the heat insulated container needs to be cut in order to measure
the film thickness and a container that has been cut cannot be used
as a product. Therefore, whether or not a heat insulated container
has a predetermined heat retaining performance needs to be
determined directly, not by measuring the film thickness, but by
measuring the temperature of hot water that has been poured into
the heat insulated container a few hours prior to measurement,
after the heat insulated container has been assembled up to the
final process. This examination is time consuming, and results in
increased manufacturing cost. Also, even if it is determined that
the heat retaining performance of the heat insulated container does
not meet a criterion, the radiation preventing film cannot be
re-coated on a heat insulated container that has already been
completed, and the heat insulated container is discarded. As a
result, the overall manufacturing cost increases.
[0006] The present invention has been achieved to solve these
problems, and it is an object of the present invention to provide a
heat insulated container having a constant heat insulation
performance, in which the presence of this heat insulation
performance can be non-destructively confirmed.
[0007] The present inventors earnestly carried out research in
order to solve the problems mentioned above and, as a result, have
discovered that there is a constant relationship between the
average particle diameter of particles of the radiation preventing
film surface and its heat retaining performance. Consequently, it
has been discovered that a constant performance can be ensured by
maintaining this particle diameter at or above a predetermined
value, leading to the present invention.
[0008] A heat insulated container according to a first aspect of
the present invention, is a heat insulated container formed by
coating a radiation preventing film on at least one surface of an
external surface of an internal glass container and an internal
surface of an external glass container, disposing the internal
container inside the external container with a gap provided
therebetween, joining an opening area of the internal container
with an opening area of the external container, and evacuating the
gap to a vacuum and sealing it, wherein an average particle
diameter of particles on the surface of the radiation preventing
film is a predetermined value or more.
[0009] A heat insulated container according to a second aspect of
the present invention, is a heat insulated container formed by
coating a radiation preventing film on at least one surface of an
external surface of an internal glass container and an internal
surface of an external glass container, disposing the internal
container inside the external container with a gap provided
therebetween, joining an opening area of the internal container
with an opening area of the external container, and evacuating the
gap to a vacuum and sealing it, wherein an average particle
diameter of particles on the surface of the radiation preventing
film on a part present in at least a side portion of the heat
insulated container is a predetermined value or more.
[0010] A heat insulated container according to a third aspect of
the present invention is characterized in that in the foregoing
aspects, the predetermined value is 50 nm.
[0011] A heat insulated container according to a fourth aspect of
the present invention is characterized in that in any one of the
foregoing aspects, the film thickness of the radiation preventing
film is 150 nm or more.
[0012] A heat insulated container according to a fifth aspect of
the present invention is characterized in that in any one of the
foregoing aspects, the radiation preventing film is an ITO
film.
[0013] According to the heat insulated container of the present
invention, by making the average particle diameter of the particles
on the surface of the radiation preventing film to be a
predetermined value or more, sufficient heat retaining performance
can be obtained. In addition, since the particle diameter can be
measured non-destructively by observation from the outside,
examination can be made quickly and, in the case where the coating
is judged to be insufficient, a film can be formed over the top.
Therefore, the examined heat insulated container is not wasted, and
the overall manufacturing cost can be reduced as a result.
[0014] The portion of the radiation preventing film that greatly
influences the heat retaining performance of the heat insulated
container is the portion on the side of the heat insulated
container. Therefore, as long as the average particle diameter of
the surface particles on the portion of the radiation preventing
film on at least the side portion of the heat insulating container
is a predetermined value or more, sufficient heat retaining
performance can be ensured.
[0015] Moreover, by making the average particle diameter of the
surface particles of the radiation preventing film to be 50 nm or
more, a heat insulating container provided with the radiation
preventing film, after being filled with 1000 cc of hot water at
95.degree. C. and sealed, and then left in a room of a temperature
of 20.degree. C. for six hours, will be able to maintain the
temperature of the hot water thereinside at 60.degree. C. or
more.
[0016] Moreover, by making the thickness of the radiation
preventing film to be 150 nm or more, a heat insulating container
provided with the radiation preventing film, after being filled
with 1000 cc of hot water at 95.degree. C. and sealed, and then
left in a room of a temperature of 20.degree. C. for six hours,
will be able to maintain the temperature of the hot water
thereinside at 60.degree. C. or more.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a sectional view of a heat insulated container of
a preferred embodiment of the present invention.
[0018] FIG. 2 is a graph showing a relationship between an ITO
particle diameter, heat retaining performance, and the thickness of
an ITO film.
[0019] FIG. 3 is a graph showing a relationship between an ITO
particle diameter, heat retaining performance, and the thickness of
an ITO film under conditions different from that of FIG. 2.
[0020] FIG. 4 shows enlarged photographs of ITO films of various
particle diameters.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Hereunder is a description of a preferred embodiment of the
present invention, with reference to the accompanying drawings.
[0022] FIG. 1 is a sectional view of a heat insulated container 10
in the embodiment of the present invention. As shown in the figure,
the heat insulated container 10 of the present embodiment includes
a glass internal container 12, and a glass external container 16
arranged outside of the internal container 12 with a gap 14 having
a constant width. The external container 16 is formed by joining an
upper external container 16a and a lower external container 16b
with each other, and the internal container 12 and the upper
external container 16a are joined with each other at an opening
area 18. The gap 14 between an internal surface of the external
container 16 and an external surface of the internal container 12
is maintained in a vacuum state. Furthermore, the external surface
of the internal container 12 is coated with an ITO film 20 that
serves as a radiation preventing film for reducing heat radiation.
This ITO film 20 is coated by means of a sputtering method and the
surface thereof, when observed from the outside, has particles
having a diameter at or above a predetermined value. The entire
surface of the ITO film 20 in the present embodiment has particles
of a diameter at or above the predetermined value. However, it is
not limited to this, and only the average particle diameter of the
surface particles on at least a portion present in a side section
22 of the heat insulated container 10 need to be of a predetermined
value or more.
[0023] Here, this predetermined diameter refers to the minimum
particle diameter at which, even after filling and sealing 1000 cc
of hot water at 95.degree. C. inside the heat insulated container
provided with the ITO film, the surface of which has particles of a
diameter at or above this predetermined value, and then leaving it
in a room temperature at 20.degree. C. for six hours, the
temperature of the hot water inside the heat insulated container is
still maintained at 60.degree. C. or more. In the present
specification, the temperature of the hot water after 1000 cc of
hot water at approximately 95.degree. C. has been filled in and
sealed inside the heat insulated container and the container has
been left in a room at 20.degree. C. for six hours, is referred to
as the heat retaining performance, and this 60.degree. C. is the
minimum temperature that the functionality of a heat insulated
container is generally required to achieve.
[0024] Therefore, the temperature of the hot water inside the heat
insulated container 10 will be measured at 60.degree. C. or more if
1000 cc of the hot water at 95.degree. C. has been filled in and
sealed inside the heat insulated container 10 of the present
embodiment and the container has been left in a room at 20.degree.
C. for six hours.
[0025] Thus, the heat insulated container 10 of the present
embodiment is a heat insulated container 10 formed by coating the
ITO film 20 on the external surface of the glass internal container
12, disposing the internal container 12 inside the external
container 16 with the gap 14, joining the internal container 12 and
the external container 16, and evacuating the gap 14 to a vacuum
and sealing it, wherein the average particle diameter of the
particles on the surface of the ITO film 20 is at the predetermined
value or more.
[0026] According to this heat insulated container 10, by making the
average particle diameter of the particles on the surface of the
ITO film 20 to be of the predetermined value or more, the heat
retaining performance of 60.degree. C. can be obtained.
Furthermore, since the particle diameter can be non-destructively
examined by external observation, the examination can be carried
out quickly. Moreover, even if the coating is determined to be
insufficient, a film can be additionally formed on the coated ITO
film since it has been non-destructively examined. Therefore, the
examined heat insulated container is not wasted, and the overall
manufacturing cost can be reduced as a result.
[0027] In the present embodiment the ITO film 20 is used as the
radiation preventing film. However, the type of the radiant heat
preventing film is not limited to this, and it may be a metal oxide
(semiconductor) such as ZnO, SiO.sub.x, SnO.sub.2, or TiO.sub.x.
The average particle diameter of the surface particles of the
radiation preventing film in this case is a particle diameter that
is at least the minimum particle diameter at which, after filling
and sealing 1000 cc of hot water at 95.degree. C. inside a heat
insulated container provided with the radiation preventing film,
and then leaving it a room at 20.degree. C. for six hours, the
temperature of the hot water inside the heat insulated container
can be maintained at 60.degree. C. or more. Moreover, in the
present embodiment the ITO film 20 is coated on the external
surface of the internal container 12. However the surface to be
coated is not limited to this, and it may be another surface, for
example, the internal surface of the external container 16 or the
like.
EXAMPLE 1
[0028] An investigation was made into the relationship between: the
average particle diameter (ITO particle diameter) of the surface
particles of an ITO film; the thickness of the ITO film; and the
heat retaining performance of a finished product of a heat
insulated container provided with an internal container covered
with the ITO film, for the case where the ITO had been sputtered
onto the external surface of the internal container in an
atmosphere where the weight ratio of argon to oxygen was 76 to
7.
[0029] Graph A in FIG. 2 is a graph showing the relationship
between heat retaining performance and ITO particle diameter, with
the heat retaining performance (.degree. C.) of a heat insulated
container on the vertical axis, and the ITO particle diameter (nm)
on the horizontal axis. Moreover on the left side of the graph, a
heat retaining performance scale is shown. As this graph A shows,
in the case of a heat insulated container in which the external
surface of the internal container is covered with an ITO film with
surface particles of an average particle diameter of 50 nm or more,
even after 6 hours, the temperature of the hot water can be
maintained at 60.degree. or more. Moreover, even if the particle
diameter increases, the temperature retaining performance does not
increase proportionately, and above 150 nm the influence of
particle diameter on heat retaining performance becomes smaller. In
particular, over 200 nm, even if the particle diameter is
increased, there is almost no change in the heat retaining
performance. Therefore, under the conditions of the present
example, the particle diameter is preferably 50 nm or more, and
more preferably 60 nm or more. Furthermore, considering sputtering
efficiency, the particle diameter is preferably no more than 200
nm, and considering efficiency still further, it is preferably no
more than 150 nm.
[0030] Furthermore, graph B is a graph showing the relationship
between the ITO film thickness and the particle diameter, with the
ITO film thickness (nm) shown on the vertical axis, and the
diameter of the ITO particles (nm) shown on the horizontal axis as
in graph A. The right hand side of the graph shows a scale of the
ITO film thickness. This straight line deviates slightly from the
actual plot. However, this is because this straight line represents
an approximation formula found from the measured values shown in
FIG. 3 of an example 2 described below. According to this graph, a
particle diameter of 50 nm corresponds to a film thickness of 150
nm, a particle diameter of 60 nm to a film thickness of 200 nm, a
particle diameter of 200 nm to a film thickness of 800 nm, and a
particle diameter of 150 nm to a film thickness of 600 nm.
Therefore, expressing the conditions of the above particle
diameters as film thicknesses, the ITO film is preferably 150 nm or
more, and more preferably 200 nm or more. Furthermore, considering
sputtering efficiency, the ITO film thickness is preferably no more
than 800 nm, and considering efficiency still further, it is
preferably no more than 600 nm.
[0031] From the result of this experiment, it can be seen that in a
heat insulated container 10 covered with an ITO film formed by
sputtering ITO in an atmosphere of an argon to oxygen weight ratio
of 76 to 7, in the case where the average particle diameter of the
surface particles is 50 nm or more, even after six hours, a heat
retaining performance of at least 60.degree. C. will be maintained.
Moreover, it can be seen that in the case where the ITO film
thickness is 150 nm or more, even after six hours has elapsed a
heat retaining performance of at least 60.degree. C. will be
maintained.
EXAMPLE 2
[0032] An investigation was made into the relationship between: the
average particle diameter (ITO particle diameter) of the surface
particles of an ITO film; the thickness of the ITO film; and the
heat retaining performance of a finished product of a heat
insulated container provided with an internal container covered
with that ITO film, for the case where the ITO had been sputtered
onto the external surface of the internal container 12 in an
atmosphere where the weight ratio of argon to oxygen was 76 to
12.
[0033] Graph A in FIG. 3 is a graph showing the relationship
between heat retaining performance and ITO particle diameter, with
the heat retaining performance (.degree. C.) of a heat insulated
container on the vertical axis, and the ITO particle diameter (nm)
on the horizontal axis. Moreover, as with FIG. 2, on the left side
of the graph, a heat retaining performance scale is shown. As this
graph A shows, even under different conditions from those of
example 1, it can be seen that in the case of a heat insulated
container in which the external surface of the internal container
is covered with an ITO film with surface particles of an average
particle diameter of 50 nm or more, even after 6 hours, the
temperature of the hot water can be maintained at 60.degree. or
more. Moreover, as with example 1, even if the particle diameter
increases, the temperature retaining performance does not increase
proportionately, and above 120 nm, the influence of particle
diameter on heat retaining performance becomes smaller. In
particular, over 150 nm, even if the particle diameter is
increased, there is almost no change in the heat retaining
performance. Therefore, under the conditions of the present
example, the particle diameter is preferably 50 nm or more, and
more preferably 60 nm or more. Furthermore, considering sputtering
efficiency, the particle diameter is preferably no more than 150
nm, and considering efficiency still further, it is preferably no
more than 120 nm.
[0034] Furthermore, graph B is a graph showing an approximation
formula found from actual measured values, of the relationship
between the ITO film thickness and the ITO particle diameter, with
the ITO film thickness (nm) shown on the vertical axis, and the
diameter of the ITO particles (nm) shown on the horizontal axis as
in graph A. The right hand side of the graph shows a scale of the
ITO film thickness. According to this graph, a particle diameter of
50 nm corresponds to a film thickness of 150 nm, a particle
diameter of 60 nm to a film thickness of 200 nm, a particle
diameter of 120 nm to a film thickness of 500 nm, and a particle
diameter of 150 nm to a film thickness of 600 nm. Therefore,
expressing the conditions of the above particle diameters as film
thicknesses, the ITO film is preferably 150 nm or more, and more
preferably 200 nm or more. Furthermore, considering sputtering
efficiency, the ITO film thickness is preferably no more than 600
nm, and, considering efficiency still further, it is preferably no
more than 500 nm.
[0035] From the result of this experiment, it can be seen that in a
heat insulated container covered with an ITO film of ITO sputtered
in an atmosphere of an argon to oxygen weight ratio of 76 to 12, in
the case where the average particle diameter of the surface
particles is 50 nm or more, even after six hours, a heat retaining
performance of at least 60.degree. C. will be maintained. Moreover,
is can be seen that in the case where the ITO film thickness is 150
nm or more, even after six hours has elapsed a heat retaining
performance of at least 60.degree. C. will be maintained.
[0036] FIG. 4 is enlarged photographs of the surfaces of ITO films.
As these photographs show, the particles of the ITO film surface
are not only spherical, and particles of differing sizes are mixed
together. Particularly where the particles become as large as
approximately 0.2 .mu.m for example, compared with particles of
approximately 0.06 .mu.m, the shape may become elliptical or
polygonal, and the size becomes varied. In the present
specification, the average particle diameter of the particles on
the ITO film surface refers to the average diameter of a particle
of average size, as shown in the photograph.
The preferred embodiment of the present invention has been
described above, however the present invention is not limited to
the above embodiment, and various modifications are possible.
* * * * *