U.S. patent application number 11/990538 was filed with the patent office on 2009-09-17 for heat source and heating device.
Invention is credited to Hisao Kimura, Yumiko Mine, Yukio Urume, Kaoru Usui.
Application Number | 20090229594 11/990538 |
Document ID | / |
Family ID | 37771363 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090229594 |
Kind Code |
A1 |
Usui; Kaoru ; et
al. |
September 17, 2009 |
Heat source and heating device
Abstract
The heat source 1 comprises a bag 10 and a heat-generating
composition 20 containing aluminum powder and calcium oxide powder,
packed in the bag 10. The bag 10 is formed by a packing material
made of a base material of nonwoven fabric of which one surface is
coated with a watertight layer. The packing material being
punctured with a plurality of pinholes and has a water permeable
rate of 45 to 310 milliliter/min/1 cm.sup.2 measured when head of
water is 27 cm. The heat source 1 can satisfy preferable
temperature conditions including rate of water temperature rise,
risen temperature of the water, duration of the risen temperature
of water, rate of vapor temperature rise, risen temperature of the
vapor and duration of the risen temperature of vapor under
conditions in which a heating device is conventionally used.
Accordingly, a heat source capable of causing a rapid and stable
heat-generating reaction and a heating device using the heat source
can be provided.
Inventors: |
Usui; Kaoru; (Tochigi,
JP) ; Urume; Yukio; (Tochigi, JP) ; Kimura;
Hisao; (Tochigi, JP) ; Mine; Yumiko; (Tochigi,
JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
220 Fifth Avenue, 16TH Floor
NEW YORK
NY
10001-7708
US
|
Family ID: |
37771363 |
Appl. No.: |
11/990538 |
Filed: |
June 23, 2006 |
PCT Filed: |
June 23, 2006 |
PCT NO: |
PCT/JP2006/312579 |
371 Date: |
February 15, 2008 |
Current U.S.
Class: |
126/263.08 |
Current CPC
Class: |
C09K 5/18 20130101; A47J
36/28 20130101; B65D 81/3484 20130101 |
Class at
Publication: |
126/263.08 |
International
Class: |
F24J 1/00 20060101
F24J001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 22, 2005 |
JP |
2005-239374 |
Claims
1. A heat source comprising a bag and a heat-generating composition
containing aluminum powder and calcium oxide powder, packed in said
bag, wherein said bag is formed by a packing material made of a
base material of nonwoven fabric of which one surface is coated
with a watertight layer, said packing material being punctured with
a plurality of pinholes and said packing material has a water
permeable rate of 45 to 310 milliliter/min/1 cm.sup.2 measured when
head of water is 27 cm.
2. A heating device comprising: a heat source according to claim 1;
a container having an exhaust vent and water for activating a
heat-generating reaction, wherein said heat source is put in said
container together with a subject to be heated, said water is added
to said container to be reacted with said heat source and the
subject is heated by the generated heat.
3. A heating device according to claim 2, wherein said subject is
attached to the lid mounted at the upper portion of said container
and is heated by water vapor produced by evaporating said water.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat source activated by
adding water and a heating device to heat a food (cooked food such
as a retort-packed food and canned drink) or other supplies such as
a hand-towel, using the heat source.
BACKGROUND ART
[0002] As a heat source activated by adding water, a mixture of
aluminum powder and calcium oxide powder has been popularly used
for a heat-generating composition (referring to Japanese Patent
number 3467729, for example). And, a heating device to heat a lunch
bag or Japanese sake, or to re-heat a cooked food such as a
retort-packed food in emergency situations, which uses the heat
source, has been also known.
[0003] In such the heat-generating composition, the calcium oxide
powder is reacted with the water to generate heat and also calcium
hydroxide produced by the reaction is reacted with the aluminum
powder to generate heat. The group of reactions makes it possible
to generate enough amounts of heat to warm the food within a short
period. The above Japanese Patent shows that the disclosed
heat-generating composition generates heat of about 100.degree. C.
after about 30 seconds from the reaction and the temperature is
kept for 20 minutes or longer. And, the heat-generating composition
has advantages in which it reacts without generating odor and a
small amount of the composition is enough for generating sufficient
amounts of heat.
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0004] In the aforesaid heating device, the heat-generating
composition is packed with an inner bag made by nonwoven fabric and
further tightly packed with a watertight outer bag. When to be
used, the packed heat-generating composition is taken out of the
outer bag and comes in contact with water, resulting in that the
heat-generating composition in the inner bag contacts the water to
be reacted. The water permeates the inner bag made by nonwoven
fabric and reacts with the heat-generating composition in the inner
bag. In this case, it is considered that the faster the water
contacts the heat-generating composition, the faster the
heat-generating reaction proceeds. The generated heat diffuses
through the heated water and water vapor. And, it is also
considered that the higher the water permeability of the inner bag
is, the faster the rate of the heat diffusion is. Accordingly, it
is possible that an efficiency of the water permeation of the inner
bag (water permeability) influences the proceeding of the
heat-generating reaction of the heat-generating composition.
However, in such the heating devices, development and proposal
concerning to the water permeability of the inner bag have not been
done.
[0005] In view of this regard, the present invention focuses
attention on the permeability of the inner bag and the object of
the present invention is to provide a heat source capable of a
rapid and stable heat-generating reaction and a heating device
using the heat source.
Means of Solving the Problems
[0006] A heat source according to the present invention comprises a
bag and a heat-generating composition containing aluminum powder
and calcium oxide powder, packed in said bag, wherein said bag is
formed by a packing material made of a base material of nonwoven
fabric of which one surface is coated with a watertight layer, said
packing material being punctured with a plurality of pinholes and
said packing material has a water permeable rate of 45 to 310
milliliter/min/1 cm.sup.2 measured when head of water is 27 cm.
[0007] A heat-generating composition containing aluminum powder and
calcium oxide powder is reacted with water to cause the following
heat-generating reaction:
CaO+H.sub.20.fwdarw.Ca(OH).sub.2+15.2 Kcal,
2Al+3Ca(OH).sub.2.fwdarw.3CaO.Al.sub.2O.sub.3+3H.sub.2+47 Kcal.
[0008] According to the present invention, by controlling water
permeable rate of the bag, the proceeding of the heat-generating
reaction is controlled. That is, when a water permeable rate of the
inner bag is set to 45 to 310 milliliter/min/1 cm.sup.2, preferably
45 to 190 milliliter/min/1 cm.sup.2, and more preferably 60 to 170
milliliter/min/1 cm.sup.2 measured when head of water is 27 cm,
preferable temperature conditions including rate of water
temperature rise, risen temperature of the water, duration of the
risen temperature of water, rate of vapor temperature rise, risen
temperature of the vapor and duration of the risen temperature of
vapor under conditions in which a heating device is typically used
can be obtained. And, leakage of the heat-generating composition
from the bag can be prevented.
[0009] Examples of the heat-generating composition and nonwoven
fabric for use in the prevent invention are described below.
[0010] Examples of the nonwoven fabric include natural fabric such
as cotton and wool; regenerated fiber such as viscose (rayon) and
cupra; polyamide such as nylon 6, nylon6,6; straight-chain or
branched polyesters having 20 or less carbon atoms such as
polyethylene terephthalate, polytrimethylene terephthalate,
polybutylene terephalate, polylactic acid and polyglycolic acid;
polyolefins such as polyethylene and polypropylene; and synthetic
fiber such as acrylic. Two or more kinds of those materials may be
used together. The nonwoven fabric may be made by a spunlaced
method, spunbond method and the like.
[0011] Exemplary properties of the nonwoven fabric are followed:
basis weight (g/m.sup.2); 40.about.70, thickness (.mu.m);
170.about.460, longitudinal tensile strength (N/5 cm);
35.about.380, transverse tensile strength (N/5 cm); 13.about.165,
longitudinal extensibility (%); 80 and below and transverse
extensibility (%); 120 and below.
[0012] The watertight layer may be formed by laminating a
synthetic-resin film on the nonwoven fabric. Exemplary
synthetic-resin films include polyolefin resin such as polyethylene
and polypropylene; polyamide resin; polyester resin; polyvinyl
chloride resin; polystyrene resin; copolymer polyamide resin;
copolymer polyester resin; ethylene-vinyl acetate resin; elastomer;
and mixed resin of two or more of those resins. The synthetic-resin
film may be a single layer or laminated layer. The synthetic-resin
film has a thickness of 0.01 to 0.3 mm, preferably 0.02 to 0.1
mm
[0013] When the heat-generating composition containing aluminum
powder and calcium oxide powder has a weight of 3 g or more, it
makes possible to heat a subject such as hand towel. A weight ratio
of the aluminum powder to the calcium oxide powder is set to
10:90.about.60:40. Especially, in view of rate of temperature rise
and duration of the risen temperature, a weight ratio of the
aluminum powder to the calcium oxide powder is preferably set to
35:65.about.50:50.
[0014] The aluminum powder preferably has following grain size
distribution: .about.45 .mu.m; 35.about.60%, 45.about.63 .mu.m;
15.about.30%, 63.about.75 .mu.m; 5.about.25% and +75 .mu.m;
10.about.28%. The calcium oxide powder preferably has following
grain size distribution: .about.75 .mu.m; 10.about.55%,
75.about.150 .mu.m; 25.about.55% and +150 .mu.m; 0.about.65%.
[0015] A heating device according to the present invention
comprises: a heat source described above; a container having an
exhaust vent and water for activating a heat-generating reaction,
wherein said heat source is put in said container together with a
subject to be heated, said water is added to said container to be
reacted with said heat source and the subject is heated by the
generated heat.
[0016] Examples to be heated by the heating device include a food
such as a retort-packed food, canned drink, boiled egg and lunch
bag, and other supplies such as a hand towel.
[0017] The container may have any forms including a bag, box and
pan. The exhaust vent is for discharging H.sub.2 and H.sub.2O
produced by the aforesaid heat-generating reaction. A size and
number of the port is selected such that expansion and breakage of
the container can be prevented while keeping heat-retaining
property.
[0018] In the present invention, it is possible to attach said
subject to the lid mounted at the upper portion of said container
and to heat the subject by water vapor produced by evaporating said
water. This case is suitable for heating a hand-towel.
ADVANTAGEOUS EFFECT OF THE INVENTION
[0019] As described above, according to the present invention, a
heat source and a heating device using the same, having preferable
temperature conditions including rate of water temperature rise,
risen temperature of the water, duration of the risen temperature
of water, rate of vapor temperature rise, risen temperature of the
vapor and duration of the risen temperature of vapor under
conditions in which a heating device is typically used, can be
provided. And, the present invention shows that heat-generating
ability of the heat source can be controlled by water permeability
of the inner bag as well as the property of the heat-generating
composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a drawing showing a structure of a heat source
according to the present invention; FIG. 1A is a plane drawing and
FIG. 1B is a cross-section drawing;
[0021] FIG. 2 is a drawing showing a heating device according to
the present invention;
[0022] FIG. 3 is a drawing showing the water permeable rate
measuring method in the present invention;
[0023] FIG. 4 is a graph showing a relation between the air
permeable rate and the water permeable rate;
[0024] FIG. 5 is a drawing showing the method for measuring the
temperature;
[0025] FIG. 6 is a graph showing a relation between the water
temperature and measuring time of each sample;
[0026] FIG. 7 is a graph showing a relation between the
environmental temperature and measuring time of each sample;
[0027] FIG. 8 are drawings showing a structure of a heating device
according to the second embodiment of the present invention; FIG.
8A is a perspective drawing and FIG. 8B is a sectional front
drawing; and
[0028] FIG. 9 is a drawing showing the method for measuring the
temperature.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] Hereinafter, preferred embodiments of the present invention
will be precisely described, referring to the drawings.
[0030] First, water permeability of an inner bag and a relation
between the water permeability and temperature of a heat source
will be described.
<Water Permeability>
[0031] Sample bags made by various base materials which are
punctured with pinholes in various densities were prepared. And,
water permeability (water permeable rate) of each sample was
measured.
(1) Base Material
[0032] As the base material, a non water-shedding nonwoven fabric
(made by 100% cotton, CO40s/PP40, manufactured by Unitika Ltd.) was
used. The nonwoven fabric has the following properties: basis
weight (g/m.sup.2); 40, thickness (.mu.m); 330, longitudinal
tensile strength (N/5 cm); 35, transverse tensile strength (N/5
cm); 15, longitudinal extensibility (%); 25 and transverse
extensibility (%); 75. The nonwoven fabric is made by a spunlaced
method in which columnar water flow injects toward fibers at high
pressure to entwine the fibers and thus to produce a nonwoven
fabric. The spunlaced method allows a production of a highly
flexible napless nonwoven fabric having high drape property. A
nonwoven fabric produced by the method is used for livelihood
materials such as diaper, medical supplies, food supplies and
cleaning supplies. On one surface of the nonwoven fabric, a
water-resistant layer (made by polypropylene) was laminated. Or,
the water-resistant layer may be made by a heating bonding and the
like in exchange for the laminating. The water-resistant layer had
a thickness of 40 .mu.m.
(2) Pinholes
[0033] Each of the prepared base materials was punctured with
pinholes in various densities using a pinhole opening machine,
which comprises a roller on which needles were arranged at
intervals of 3.3 mm in the transverse direction and at intervals of
3 mm in the longitudinal direction and a base material supporting
roller confronting to the former roller. Or, another type of the
pinhole opening machine may be used, which is provided with needles
capable of being heated and the heated needles are made to contact
the laminated film to fuse the film, resulting in opening pinholes.
After the base material was supported to the base material
supporting roller, each of the rollers rotated in opposite
directions. As the result, pinholes having a diameter of 0.1 to 0.4
mm were formed on the base material in substantially the uniform
density over the almost full area. And, a number of rows of the
needles on the roller, or a number of times in which the roller
passed on the base material was adjusted to vary the density of the
pinholes of the base material. In this embodiment, ten base
materials having various pinhole densities were prepared. The
pinhole densities varied over a range of 800 to 8000/100 cm.sup.2.
If the diameter of the pinhole is larger, the small particulate
heat-generating composition may be leaked through the pinhole from
the bag, causing unfavorable situation. Accordingly, the pinhole
density is preferably 2000 to 8000/100 cm.sup.2, more preferably
3800 to 7100/100 cm.sup.2.
[0034] Each of the base materials was cut into a piece having a
size of 50 mm by 50 mm to prepare a sample for measuring water
permeability.
(3) Water Permeability
[0035] There is no official standard showing water permeability of
fabric and the like. According to a method for measuring water
permeable rate of perforated film, water permeability of each
sample was examined by a water permeable rate measuring method,
described later.
[0036] FIG. 3 is a drawing showing the water permeable rate
measuring method in the present invention.
[0037] A stainless-steel measuring tank 51 (inside dimension of
335.times.535.times.178 mm) was prepared and filled with
ion-exchange water of 23.+-.3.degree. C. An inflow pipe 53 from
which the ion-exchange water flowed in the tank 51 was formed at
the under portion of the side wall of the tank 51 and an overflow
pipe 55 was formed at the upper portion of the side wall of the
tank 51. The pipes 53 and 55 were openable and closable by cocks 54
and 56, respectively. The ion-exchange water was poured into the
tank 51 from the inflow pipe 53 and overflowed through the overflow
pipe 55.
[0038] An outflow pipe 57 (diameter of 19.05 mm) extending downward
was formed on the bottom of the tank 51. The outflow pipe 57 was
openable and closable by a cock 58. The sample base materials S was
temporarily attached to the opening of the outflow pipe 57 by a
rubber band 59 with the watertight surface of the sample S being
upside. Then, the periphery of the sample was closely attached to
the pipe by a sealing tape to block the opening with the sample S
and then further tightly attached by a water impermeable adhesive
tape made by polypropylene. A distance H between the opening of the
outflow pipe 57 and the overflow port of the overflow pipe 55 was
270.+-.9.5 mm (head of water). Under the opening of the outflow
pipe 57, a collection vessel 61 was disposed. The collection vessel
61 was set on a measurement apparatus (not shown, GF-3000,
manufactured by A&D Co., Ltd.).
[0039] The tank 51 was kept the overflow state with the both cocks
54 and 56 opened. When the cock 58 of the outflow pipe 57 was
opened, the water was collected by the vessel 61. And, the amount
(milliliter) of the collected water was weighed. In this case,
after an amount of the permeated water per unit time had got
constant (after a variation in amount of the permeated water per 10
seconds was within 5% at least consecutive three times), an amount
of the permeated water measured in any one minute during the
measurement for one minute or more was defined as a water permeable
amount (milliliter). And, a water permeable amount per one minuet
per 1 cm.sup.2 of the sample was converted to water permeable rate
(milliliter/min/cm.sup.2). A specific gravity of the ion-exchange
water is set to 1.000 (g/cm.sup.3).
[0040] Then, a relation between the measured water permeable rate
and air permeability, which had been publicly known, was examined.
Because, the measurement of the water permeable rate needs
troublesome handling, and, therefore if the water permeable rate is
correlated with the air permeability, the measurement of the air
permeability can be employed in exchange for the measurement of the
water permeable rate.
[0041] The air permeability was measured using a gurley type
densometer (range; 300 ml, timer; s,t<1, a diameter of measuring
section; 30 mm, manufactured by Toyo Seiki Seisaku-Sho, Ltd., based
on JIS P8117). The measured value (sec/300 ml) was converted to an
air permeable rate (milliliter/min/cm.sup.2).
[0042] The prepared ten samples having various pinhole densities
were examined for water permeability using the aforesaid measuring
apparatus and also for air permeability using the gurley type
densometer.
[0043] Table 1 shows the measured air permeability, air permeable
rate converted from the measured air permeability, the measured
water permeability and water permeable rate converted from the
measured water permeability.
TABLE-US-00001 TABLE 1 air permeability water permeability measured
air permeable measured water permeable Sample value rate value rate
No. (sec/300 ml) (ml/min./cm.sup.2) (ml/min.) (ml/min./cm.sup.2) 1
40.7 62.57 60.66 21.28 2 11.0 231.50 39.28 13.78 3 9.9 257.22 52.87
18.55 4 7.3 348.83 52.46 18.41 5 6.8 374.48 63.89 22.42 6 3.0
848.83 190.83 66.95 7 1.9 1340.25 301.80 105.89 8 1.1 2314.98
478.23 167.79 9 0.7 3637.83 739.90 259.59 10 0.5 5092.96 1024.70
359.51
[0044] FIG. 4 is a graph showing a relation between the air
permeable rate and the water permeable rate. The vertical axis
indicates the water permeable rate converted from the measured
water permeability, and the horizontal axis indicates the air
permeable rate converted from the air permeability measured by the
gurley type densometer.
[0045] As shown in the graph, although the values varies when the
both rates are small (when the air permeable rate is less than 400
ml/min/cm.sup.2), the water permeable rate can be expressed by a
direct function of the air permeable rate when the both rate are
larger. Accordingly, the graph shows that the water permeable rate
is correlated with the air permeable rate. From the graph, a ratio
of the water permeable rate to the air permeable rate is
substantially equal to 1/13 in a case of the packing material of
the present invention.
[0046] The following examinations were carried out using the air
permeable rate capable of converting to the water permeable rate
because the measurement of the water permeable rate is a
time-consuming process as described above. Suppose that the water
permeable rate was expressed by the air permeable rate/13.
<Relation Between the Water Permeability of the Bag and the
Temperature of Heat Source>
[0047] A heat source was produced using each of the prepared bags.
And, a relation between the temperature of the heat source and the
air permeability of the bags was examined.
(1) Heat-Generating Composition
[0048] As the heat-generating composition, a mixed powder of
calcium oxide powder (manufactured by Tagen lime industry) of 30 g
and aluminum powder (manufactured by YAMAISHI METALS Co., Ltd.) of
20 g was used.
[0049] The calcium oxide powder has the following grain size
distribution: .about.75 .mu.m; 11.69%, 75.about.150 .mu.m; 29.27%
and +150 .mu.m; 59.04%. The aluminum powder has the following grain
size distribution: .about.45 .mu.m; 43.52%, 45.about.63 .mu.m;
19.85%, 63.about.75 .mu.m; 18.90% and +75 .mu.m; 17.73%.
[0050] The calcium oxide powder consists of the following elements:
calcium oxide (measured by an EDTA titration method (NN
indicator)); 93% or more, carbon dioxide (measured by a Sutorelain
method); 2.0% and below and impurities (measured by an EDTA
titration method, perchloric acid method, absorption spectroscopy);
3.2% and below. The impurities include silicon dioxide, aluminum
oxide, ferric oxide and magnesium oxide.
(2) Samples of the Bag
[0051] The same nonwoven fabric as that used for the measurement of
the water permeability was used. By varying a number of times in
which the roller of the pinhole opening machine passed on the base
material, the samples of nonwoven fabrics in various air permeable
rates, described below, were prepared.
[0052] Sample 1; 170.about.250 (milliliter/min/cm.sup.2),
[0053] Sample 2; 250.about.400 (milliliter/min/cm.sup.2),
[0054] Sample 3; 400.about.600 (milliliter/min/cm.sup.2),
[0055] Sample 4; 600.about.1300 (milliliter/min/cm.sup.2),
[0056] Sample 5; 1300.about.2000 (milliliter/min/cm.sup.2),
[0057] Sample 6; 2000.about.3600 (milliliter/min/cm.sup.2),
[0058] Sample 7; 3600.about.4000 (milliliter/min/cm.sup.2) and
[0059] Sample 8; 4000.about.5000 (milliliter/min/cm.sup.2).
[0060] By using the samples, the bag having a receptacle for
containing the heat-generating composition was produced. The
receptacle had a size of 90 mm.times.150 mm.
(3) Method for Measuring Temperature of the Heat-Generating
Composition
[0061] FIG. 5 is a drawing showing the method for measuring the
temperature.
[0062] The heat source 1, a food F (retort-packed cooked rice) and
water of 130 g were put in a heating bag 31 having exhaust vents
32. In this example, the heating bag 31 was openable and closable
and had two exhaust vents 32. In a temperature-controlled room of
which room temperature was kept at 20.degree. C., the heating bag
31 was supported in a stainless-steel container 73 set on a heat
insulating material 71. And, for 20 minutes after the
heat-generating reaction, a temperature in the heating bag 31
(steam temperature) T1, a temperature T2 of the heated water and an
environmental temperature T3 were measured by the measuring
apparatus D.
[0063] FIG. 6 is a graph showing a relation between the water
temperature and measuring time of each sample.
[0064] FIG. 7 is a graph showing a relation between the
environmental temperature and measuring time of each sample.
[0065] The horizontal axes indicate a measuring time (minute), and
the vertical axes indicate the water temperature T2 (FIG. 6) and
environmental temperature T1 (FIG. 7).
[0066] As shown in FIG. 6, the water temperature T2 of the sample 1
having slow air permeable rate rises rapidly just after the
heat-generating reaction; begins to fall down shortly thereafter
and falls down to about 40.degree. C. after 20 minutes. And, the
water temperature T2 of the sample 2 having slow air permeable
rate, as well sample 1, rises to about 50.degree. C. at a maximum.
On the contrary, the water temperature T2 of each of the samples 3,
4 and 5 having middle air permeable rate rises just after the
heat-generating reaction, to 70.degree. C. or higher after 5
minutes and the risen temperatures is maintained for 20 minutes.
The water temperature T2 of each of the samples 6, 7 and 8 having
faster air permeable rate rises to 90.degree. C. or higher just
after the heat-generating reaction, the risen temperatures is
maintained for 10 minutes after 5 minutes and then 80.degree. C. or
higher is maintained after 20 minutes.
[0067] As shown in FIG. 7, the steam temperature (environmental
temperature) T1 of each of the samples 1, 2, 3 and 4 having slow
air permeable rate does not rise to 50.degree. C. or higher. On the
contrary, the steam temperature of each of the samples 5, 6, 7 and
8 having fast air permeable rate rapidly rises to 70.degree. C. or
higher after 2 minutes and the risen temperature of 70.degree. C.
or higher is maintained for about 10 minutes.
[0068] Next, whether the samples satisfied the following
temperature conditions required for the food heating device was
considered.
[0069] 1) To keep the water temperature of 80.degree. C. or higher
for 13 minutes or more.
[0070] 2) To keep the steam temperature of 70.degree. C. or higher
for 10 minutes or more.
[0071] 3) To rise the steam temperature to 70.degree. C. or higher
after 2 minutes from the heat-generating reaction.
[0072] Table 2 shows a result whether or not the samples satisfied
the temperature conditions.
TABLE-US-00002 TABLE 2 1) water 2) steam air permeability
temperature temperature 3) rate of steam measured air permeable
80.degree. C. or higher 70.degree. C. or higher temperature rise
Sample value rate for 13 min. or for 10 min. or 70.degree. C. or
higher No. (sec/300 ml) (ml/min./cm.sup.2) more more in 2 min. 1
ab. 10.0~15.0 170~250 x x x 2 ab. 6.0~10.0 250~400 x x x 3 ab.
4.0~6.0 400~600 x x x 4 ab. 2.0~4.0 600~1300 .smallcircle. x x 5
ab. 1.3~2.0 1300~2000 .smallcircle. .smallcircle. .smallcircle. 6
ab. 0.7~1.3 2000~3600 .smallcircle. .smallcircle. .smallcircle. 7
ab. 0.6~0.7 3600~4000 .smallcircle. .smallcircle. .smallcircle. 8
ab. 0.5~0.67 4000~5000 .smallcircle. .smallcircle.
.smallcircle.
[0073] The samples 1, 2, 3 and 4 having the air permeable rate of
1300 and below does not satisfy all of the temperature conditions.
And, the food (retort-packed cooked rice) of each sample was not
warmed. On the contrary, the samples 5, 6, 7 and 8 having the air
permeable rate of 1300 to 5000 satisfy all of the temperature
conditions. And, the foods were warmed. But, in the sample 8 having
the air permeable rate of 4000 or more, the heat-generating
composition was leaked through the pinholes of the bag. Because,
the sample, having fast air permeable rate, had any large diameter
pinholes formed by lapping the pinholes owing to many times of pass
of the needles of the pinhole opening machine.
[0074] From these results, the following were obtained:
[0075] (1) Temperature of the heat source can be controlled by the
air permeable rate of the bag.
[0076] (2) The air permeable rate of the bag required for heating a
food (retort-packed cooked rice) is 1300 to 4000
milliliter/min/cm.sup.2 (water permeable rate is about 100 to 310
milliliter/min/cm.sup.2).
[0077] Note that the sample 4 having the air permeable rate of 600
to 1300 milliliter/min/cm.sup.2 (water permeable rate is about 46
to 100 milliliter/min/cm.sup.2) satisfies the aforesaid temperature
condition (1) (to keep the water temperature at 80.degree. C. or
higher for 13 minutes or more). Accordingly, if the subject to be
heated is so small as to be soaked with the water, the sample 4 can
heat such subject. Therefore, the water permeable rate of the bag
preferable for heating a subject is 45 to 310
milliliter/min/cm.sup.2.
[0078] Next, an effect of an amount of the heat-generating
composition consisting of the calcium oxide powder and the aluminum
powder on the temperature of the heat source will be described.
<An Amount and Amount Ratio of the Heat-Generating Composition
and the Temperature>
(1) Heat-Generating Composition
[0079] By using the aforesaid aluminum powder and calcium oxide
powder, the following samples were prepared.
[0080] (1) Sample 1; aluminum powder:calcium oxide powder=50:50, a
total weight: 10 g,
[0081] (2) Sample 2; aluminum powder:calcium oxide powder=50:50, a
total weight: 5 g,
[0082] (3) Sample 3; aluminum powder:calcium oxide powder=50:50, a
total weight: 3 g and
[0083] (4) Sample 4; aluminum powder:calcium oxide powder=10:90, a
total weight: 20 g.
(2) Method for Measuring the Temperature
[0084] FIG. 9 is a drawing showing the method for measuring the
temperature.
[0085] A disposable paper towel T was attached to an inside surface
of a lid 42 of a paper box 41 of which the inside surface was
water-resistant processed. The heat source 1 produced by using each
of the prepared four samples was put in the paper box 41. And,
after applying water W in the box, the lid 41 was closed. A weight
of the water was 2.6 times of a weight of the heat-generating
composition. Then, a temperature T1 of the paper towel T, a
temperature T2 of the heated water and an environmental temperature
T3 were measured with the measuring apparatus for 3 minutes after
the heat-generating reaction. The vapor and hydrogen gas produced
by the heat-generating reaction were leaked from the clearance
between the body of the box 41 and the lid 42.
[0086] Then, whether the samples satisfied the following
temperature condition required for a heating device was
discussed.
1) To Rise the Temperature T1 of the Paper Towel to about
50.degree. C. in 3 Minutes.
[0087] Table 3 shows results whether the samples satisfied the
temperature conditions.
TABLE-US-00003 TABLE 3 paper towel temperature (T1) Sample amount
ratio weight ab. 50.degree. C. No. (aluminum:calcium oxide) (g) in
3 min. result 1 50:50 10 .circleincircle. .largecircle. 2 50:50 5
.largecircle. .largecircle. 3 50:50 3 .largecircle. .largecircle. 4
10:90 20 .largecircle. .largecircle.
[0088] The heat source using either sample satisfies the
temperature condition. Note that the sample 1 (an amount ratio of
50:50, a total weight of log) shows most preferable temperature
rise.
[0089] From the results, in a case in which the subject to be
heated is small, a heat-generating composition having a low ratio
of the aluminum powder to the calcium oxide powder of 10:90 (sample
4) can be used. And, a heat-generating composition, having a
relatively large amount ratio of the aluminum powder to the calcium
oxide powder of 50:50, needs a small total weight (3 g, sample 3).
Accordingly, an amount of high-price aluminum powder can be
reduced.
Example 1
[0090] FIG. 1 is a drawing showing a structure of a heat source
according to the present invention; FIG. 1A is a plane drawing and
FIG. 1B is a cross-section drawing.
[0091] The heat source 1 comprises a bag 10 and a heat-generating
composition 20 packed in the bag 10.
[0092] The bag 10 is made of a cotton nonwoven fabric 11
(CO40s/PP40, manufactured by Unitika Ltd.) of which inner surface
is coated with a water-resistant layer 13 made of polypropylene.
Almost full area of the bag 10 is punctured with pinholes 15 in
substantially the uniform density. The pinhole 15 has a diameter of
0.2 to 0.4 mm. The bag 10 has a water permeable rate, measured by
the aforesaid method (as shown in FIG. 3), of 100
milliliter/min/cm.sup.2. The water permeable rate can be converted
from the air permeable rate measured by the gurley type densometer.
The bag 10 has a size of 90 mm.times.155 mm.
[0093] The heat-generating composition 30 is a mixed powder of
calcium oxide powder (manufactured by Tagen lime industry) of 30 g
and aluminum powder (VA-150, manufactured by YAMAISHI METALS Co.,
Ltd.) of 20 g. The heat-generating composition 30 is packed in the
bag 10 to produce the heat source 1.
Example 2
[0094] FIG. 2 is a drawing showing a heating device according to
the present invention. In this embodiment, the heating device is
used for warming a retort-packed cooked rice.
[0095] The heating device 30 comprises a heating bag (container) 31
having exhaust vents 32; the heat source 1 shown in FIG. 1 and
water for activating a heat-generating reaction. In this
embodiment, two circular exhaust vents 32 having a diameter of 5 mm
are formed. Or, one to two exhaust vents 32 having a diameter of 10
to 15 mm, or eight to ten exhaust vents 32 having a diameter of 1
to 2 mm may be formed. The shape of the exhaust vent is not limited
to a circular shape; may be any shape capable of venting water
vapor and hydrogen gas.
[0096] The heat source 1 is packed in an air-tight outer bag during
storing in order to prevent the heat-generating composition from
contacting moisture in air.
[0097] The heat source 1, taken out of the outer bag, and the
retort-packed cooked food F were put in the container 31, water of
130 g was added and then the container 31 was sealed. The heat
source 1 caused a heat-generating reaction to heat the
retort-packed cooked rice H in the container 31. Water vapor and
hydrogen gas produced by the heat-generating reaction were vent
through the exhaust vents 32. And, after 15 minutes from the
activation of the heat-generating reaction, the retort-packed
cocked rice H was heated sufficiently. And, leakage of the
heat-generating composition did not occur.
[0098] In exchange for the aforesaid nonwoven fabric, another type
of non water repellent nonwoven fabric may be used, for example,
Soflon EMR-50 (manufactured by Kokko Paper Mfg. Co., Ltd.), which
has the following properties: basis weight (g/m.sup.2);
50.0.+-.5.0, thickness (.mu.m); 0.40.+-.0.10, longitudinal tensile
strength (N/25 mm); 41.00.+-.10.00, transverse tensile strength
(N/25 mm); 9.50.+-.3.00, longitudinal extensibility (%); 27 and
below; transverse extensibility (%); 120 and below, longitudinal 5%
modulus (n/25 mm); 17.00.+-.7.00 and transverse 50% modulus;
3.10.+-.1.00. The nonwoven fabric was made by a spunlaced
method.
Example 3
[0099] FIG. 8 are drawings showing a structure of a heating device
according to the second embodiment of the present invention; FIG.
8A is a perspective drawing and FIG. 8B is a sectional front
drawing.
[0100] The heating device 40 comprises a heating box (container)
41, the heat source 1 and water for activating a heat-generating
reaction. The heat source 1 is packed in an air-tight outer bag
during storing in order to prevent the heat-generating composition
from contacting moisture in air.
[0101] The heat source 1 comprises a bag 10 and a heat-generating
composition 20 packed in the bag 10, as well Example 1. In this
Example, the bag 10 has a size of 50 mm.times.110 mm.
[0102] The heat-generating composition is a mixed powder of calcium
oxide powder of 5 g and aluminum powder of 5 g (a total weight of
10 g).
[0103] The heating box 41 is made of a paper of which inner surface
is water-resistant processed. The upper face of the box 41 is
openable and closeable by a lid 42. On the inner surface of the lid
42, a disposable paper towel T is detachably attached.
[0104] The heat source 1, taken out of the outer bag, was put in
the container 41, water of 26 g was added and then the lid 42 was
closed. The heat source 1 caused a heat-generating reaction to heat
the disposable paper towel attached to the inner surface of the lid
42. Water vapor and hydrogen gas produced by the heat-generating
reaction were vent through a clearance between the container 41 and
the lid 42. And, after 3 minutes from the activation of the
heat-generating reaction, the paper towel was heated
sufficiently.
[0105] A weight ratio of the aluminum power and the calcium oxide
powder, weight of the heat-generating composition and properties
are not limited to the aforesaid values.
* * * * *