U.S. patent application number 09/845213 was filed with the patent office on 2001-09-20 for method of manufacturing a foot warming exothermic device and the foot warming exothermic device.
Invention is credited to Usui, Akio.
Application Number | 20010023366 09/845213 |
Document ID | / |
Family ID | 26453852 |
Filed Date | 2001-09-20 |
United States Patent
Application |
20010023366 |
Kind Code |
A1 |
Usui, Akio |
September 20, 2001 |
Method of manufacturing a foot warming exothermic device and the
foot warming exothermic device
Abstract
A method of manufacturing a foot warming exothermic device
comprises placing an exothermic composition of a viscous fluid form
by printing or coating on one surface of a thin sheet base material
and in at least one predetermined portion of the one surface to
such a configuration as to cover a desired site of a human foot,
and then placing a thin sheet covering material on the fluid
exothermic composition so as to cover the exothermic composition,
at least one or part of the base material and the covering material
being gas permeable.
Inventors: |
Usui, Akio; (Tochigi-shi,
JP) |
Correspondence
Address: |
EDWIN E. GREIGG
GREIGG & GREIGG P.L.L.C.
1423 POWHATAN STREET, UNIT ONE
ALEXANDRIA
VA
22314
US
|
Family ID: |
26453852 |
Appl. No.: |
09/845213 |
Filed: |
May 1, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09845213 |
May 1, 2001 |
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09371957 |
Aug 11, 1999 |
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6264681 |
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09371957 |
Aug 11, 1999 |
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08827760 |
Apr 10, 1997 |
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Current U.S.
Class: |
607/111 |
Current CPC
Class: |
A61F 2007/0047 20130101;
A61F 7/034 20130101; A61F 2007/0098 20130101; A43B 1/0054 20130101;
A61F 2007/026 20130101; A61F 2007/038 20130101; A43B 7/02
20130101 |
Class at
Publication: |
607/111 |
International
Class: |
A61F 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 11, 1996 |
JP |
8-115312 |
Claims
1. A foot warming exothermic device which comprises a sheet base
material, an exothermic composition in a viscous fluid form, said
exothermic composition having a sufficient amount of water to form
a barrier layer that blocks oxygen when applied in a predetermined
area of said sheet base material, a covering material covering said
exothermic composition, and at least a part of at least one of said
base material or said covering material being gas permeable.
2. A foot warming exothermic device as set forth in claim 1, in
which said exothermic device is configured to cover a whole area of
a sole of a human foot.
3. A foot warming exothermic device as set forth in claim 1, in
which said exothermic device is configured to cover at least that
part of a sole of a human foot comprising toes, instep and/or heel
of the foot.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a method of manufacturing a
foot warming exothermic device and the foot warming exothermic
device. More particularly, the invention relates to a method of
manufacturing a foot warming exothermic device which can easily
produce an ultrathin foot warming exothermic device at low cost by
placing a fluid exothermic composition on a wrapper at high speed,
can securely fix a portion or the whole of the exothermic
composition in the wrapper and prevent movement thereof, and can
well conform to the user's foot configuration and efficiently warm
a desired site of the foot when it is applied to the site, and to
the foot warming exothermic device.
[0003] (2) Description of the Related Art
[0004] In recent years, exothermic devices of the type known as
disposable body warmers have been widely used such that the
exothermic device includes an exothermic composition enclosed in a
flat pouch comprised of a gas permeable or gas-tight thin sheet
base material and a gas permeable thin sheet covering material.
[0005] It is also common to use an exothermic device having an
adhesive layer attached to one side of a pouch of the above noted
type such that the exothermic device can be pasted directly or
through underwear to the skin of a living body. Further, it has
been proposed to utilize as a hot compress an adhesive layer with a
wet pack medication incorporated or carried therein, or as a
medication-containing layer with a skin absorbable medication
incorporated or carried therein (see Japanese Patent Application
published specification No. 2-149272).
[0006] As an old saying goes, "cooled head and warmed feet", it has
been believed that warming feet is a key to good health. With
widespread use of such exothermic devices, therefore, foot warming
exothermic devices for warming the sole of the foot have now become
commercially available. Various foot warming exothermic devices of
this type have been proposed including, for example, those
disclosed in Japanese Patent Application published specifications
Nos. 2-154762, 2-172460, 5-115310, Japanese Utility Model
Applications published Nos. 6-21616 and 5-84317, and Japanese
Patent Application published No. 5-176951.
[0007] In manufacturing such a foot warming endothermic device it
is general practice to place an exothermic composition of powder
form with some water content on a predetermined site in a base
material and then cover the same with a gas permeable covering
material. Thereafter, the base material and a peripheral edge
portion of the covering material are sealingly bonded by heat
sealing or with a hot melt adhesive over and along the entire
peripheral edge portion.
[0008] Such a foot warming exothermic device of the prior art
includes an exothermic composition containing, in traditionally
appropriate proportions, a metal powder, such as iron powder, and
water, and in addition an activated carbon for accelerating heat
generation, a metal chloride for fracturing an oxide film on the
surface of the metal powder and continuously generating an
exothermic reaction, and a water retainer for preventing a sticky
effect of the composition. The exothermic composition is in the
form of a water-containing powder and is placed on a base
material.
[0009] In the case where the exothermic composition, with all its
ingredients mixed together in an appropriate blend ratio as above
noted, is placed on the base material, the trouble is that after
the blending of the ingredients into the exothermic composition and
before the foot warming exothermic device is enclosed in an outer
pouch, an exothermic reaction occurs which results in a loss of
exothermic energy and a quality degradation of the exothermic
composition. Furthermore, a reaction product resulting from the
exothermic reaction involves various harmful effects, such as
decreased yield, handling inconvenience, complicated
maintenance-related problems, limitations affecting machine
operation time as well as operator working hours, and difficulties
involved in dealing with coagulated matter.
[0010] While the exothermic composition is provided through its
water content with a wetting characteristic, the proportion of the
water content is so low as to be suitable for an exothermic
reaction, so that the exothermic composition assumes a powder form
and has only poor fluidity. This poses a problem that it is
extremely difficult to allow the composition to be uniformly
distributed within a predetermined area on the base material
through mere placement of the same in position. In view of this
fact, it is common practice to equalize the distribution of the
exothermic composition to some extent by means of a roller or the
like during the process of covering the composition with a covering
material and sealing the same. With such a method, however, the
distribution of the exothermic composition tends to become inclined
toward the source of pouch material. In order to increase the
proportion of the exothermic composition distributed in the
direction of pouch material feed, it is necessary to increase the
height of a chamber defined within the pouch, thereby making it
possible to eliminate any offset in the distribution of the
exothermic composition as by manual shaking at the time of use.
[0011] Where the foot warming exothermic device becomes thicker in
its entirety, the device feels rough and has poor hand. Moreover,
the device has inferior flexibility so that it is unable to well
conform to any complex surface irregularity at an application site
and/or any curved surface of a small curvature. The thickness
increase also results in a degradation in the extensibility or
stretchability characteristic of the device, which in turn may
result in a deformation due to the wearer's movement and a lower
capability of conformance to such movement.
[0012] Furthermore, as already mentioned, foot warming exothermic
devices of the prior art are such that although the exothermic
composition is provided through its water content with wetting
characteristics, the proportion of the water content is so low as
to be suitable for an exothermic reaction, so that the exothermic
composition assumes a powder form and has only poor fluidity.
Therefore, it is extremely difficult to cause the exothermic
composition to be uniformly distributed within a predetermined area
on the base material, so that the thickness of the foot warming
exothermic device is irregular. As such, when the device is used in
such a condition that it is affixed to an application site,
continued use of the device as affixed to the same application site
may be a cause of a low temperature burn.
[0013] With foot warming exothermic devices of the prior art, it is
impossible to completely prevent any possible displacement during
the process of manufacture or in the course of transportation in
the current status of the art.
[0014] Such foot warming exothermic device, prior to use, is
transported for delivery in a condition such that it is packaged
within an outer pouch (preservation pouch). In this stage of
transport, the exothermic composition is movable within the
exothermic device and, from the standpoint of safety maintenance,
it has been taken as an important requirement that the device be
kept uniform in thickness so as to enable the device to exhibit a
constant temperature profile throughout its entirety. In the
current practice, therefore, any such device in which the
exothermic composition is non-uniformly distributed is returned as
an off-standard product in the stage of distribution, or is
replaced upon request from the user. Hence, it is very important to
secure thickness uniformity with respect to the exothermic
composition in the stage of transportation.
[0015] In Japanese Patent Application Laid-Open No. 62-347, a
method for adhesively fixing an exothermic composition in position
is proposed. In actual manufacturing operation, however, it is
almost impossible to adhesively fix an exothermic composition in
powder form within a pouch. Even if such adhesion could be done,
the adhesion would be too weak to enable the composition to be well
fixed in position, and therefore the composition, while in use, may
become peeled off or may become a plate-like mass having little
flexibility, thus causing an uncomfortable feeling to the user.
Furthermore, the presence of the adhesive hinders contact of the
composition with air, resulting in an uneven temperature
distribution and/or temperature variations. As such, this method is
unsatisfactory for practical use.
[0016] Therefore, the inventor has made intensive research in order
to solve the above-mentioned technical problems thereby to develop
a method of manufacturing a foot warming exothermic device which
can inhibit any exothermic reaction of an exothermic composition
and prevent any possible heat loss due to heat generation during a
manufacturing operation and various harmful effects of quality
degradation and solidification of the exothermic composition, and
can manufacture ultra-thin exothermic devices at a high rate, and
which permits the exothermic composition to be uniformly
distributed and fixed within a pouch thereby to prevent any
movement and/or displacement of the exothermic composition and
suppress an excessive exothermic reaction of the composition.
[0017] It has been found as a result that the heating principle of
an exothermic device of this type is based on a heat generation
occurring with the oxidation of a metal powder, and the rate of
this oxidation, or exothermic reaction, is greatly influenced by
the quantity of water in particular.
[0018] That is, to promote this oxidation, an appropriate 10 degree
of moisture is the key, the reaction is markedly retarded if
moisture is too much or too little. A good balance between
necessary moisture and air (oxygen) supply is said to maximize the
rate of oxidation or exothermic reaction.
[0019] Too little moisture results in a shortage of moisture
necessary for the reaction though air is sufficient. Too much
moisture results in barrier layers of moisture to diminish air
supply, thereby retarding the reaction.
[0020] The inventor has found that use of a fluid exothermic
composition, that is, an exothermic composition made viscous, makes
it possible to manufacture an ultra-thin exothermic device at a
high rate of production because the composition can be easily
transferred by printing, e.g., screen printing, or coating, and
that since any excess moisture forms barrier layers of moisture to
diminish air supply thereby to substantially stop any exothermic
reaction in progress, any quality degradation of the exothermic
composition in process and various harmful effects of the
solidification of the composition can be prevented.
[0021] The inventor has also found that by causing an exothermic
composition to be formed into a viscous fluid configuration, the
exothermic composition can be uniformly distributed within a pouch
by printing, e.g., screen printing, or coating, and that when the
fluid exothermic composition is transferred or laminated on a
water-absorbable foamed film sheet, paper, corrugated board,
cardboard core paper, nonwoven cloth, woven cloth, or porous thin
sheet, or on a water absorptive layer formed on such material, the
fluid exothermic composition can be fixed in position on such
foamed thin sheet, nonwoven cloth, woven cloth, or porous thin
sheet, or on the water absorptive layer formed thereon, being
thereby prevented from movement.
[0022] Further, the inventor has found that use of a printing
technique, such as screen printing, or a lamination technique, such
as coating, enables the formation of the exothermic device to a
very thin configuration, which results in a decrease in the rate of
exothermic reaction per unit time, whereby an excessive exothermic
reaction of the exothermic composition can be suppressed.
Additionally, the inventor has found that where a fluid exothermic
composition is laminated on a Wrapper material, e.g., paper, card
board, card board core, or nonwoven cloth, such as of rayon, by
using a printing technique, such as screen printing, or a coating
technique, the stage of powder inputting can be eliminated in the
process for manufacturing an exothermic device, which simplifies
the process of factory management which must be carried out to the
satisfaction of the GMP standards in the manufacture of medical
tools and devices and medicament supplies in the future.
[0023] Further, the inventor has found that when part of the
moisture content of a fluid exothermic composition in which the
proportion of water is relatively high is absorbed into a wrapper
material, such a base material and/or covering material, barrier
layers go out of existence, whereby any possible harmful effect of
excessive moisture can be eliminated.
[0024] Further, the inventor has found that a fluid exothermic
composition acts to adhesively join the base material and the
covering material together and bites into rough surfaces of the
base material and the covering material and, therefore, that
through such anchoring effect of the exothermic composition, any
possible displacement of the composition within the exothermic
device can be prevented not only in the manufacturing process, but
also in the stage of distribution and during use by the
consumer.
[0025] Conventional foot warming exothermic devices have a drawback
that heat generation cannot completely be controlled. In some
cases, an abrupt temperature rise (to about 90.degree. C.) may
occur when the user puts off his shoes, with the result that the
duration of heating becomes extremely short. Depending upon the
type of shoes and/or individual physical constitution, such devices
often involve problems of insufficient heat generation and burn due
to excessive heating. There are many who suffer from foot cold and
a great need exists for a safe foot warming exothermic device.
[0026] The temperature of the foot sole is associated with blood
stream and is influenced by changes in ambient temperature, such as
atmospheric temperature, in delicately varied degrees, depending
upon sole temperature changes during morning, day time, and night
time, changes in physical condition, meals, and the quantity of
exercise. Of course, this is not the same with all people, there
being considerable difference among individuals.
[0027] Further, there are many factors affecting heat generation,
including type of shoes, type of socks, whether the shoe is tight
or loose, and in condition of heat insulation. Even if the
conditions for heat generation are kept constant, where the
conditions are favorable for heat generation, there may be a danger
of excessive heating, which means a danger of burn. Whilst, where
the conditions are unfavorable for heat generation, there may be
unsatisfactory heat generation, thus the device is rendered
useless.
[0028] In contrast to conventional foot warming exothermic devices,
with respect to a foot warming exothermic device having an
exothermic composition incorporated therein by transfer, it has
been found that even if the proportion of iron powder, a heat
generating material, is increased to 60% in weight ratio to the
total of all ingredients, air barrier layers (moisture-containing
layers) in a fluid which cover the iron powder or heat generating
material can become air permeable as moisture is deprived of them
as a result of an exothermic reaction of the iron powder since the
transfer of the exothermic composition is effected by using a
thickener. Furthermore, air supply can be gradually obtained
through the surface of the device. Thus, a stable heat generation
can be obtained, and if conditions for heat generation are changed,
still a favorable heat generation can be obtained.
SUMMARY OF THE INVENTION
[0029] The present invention has been developed on the basis of the
foregoing findings, and accordingly it is an object of the
invention to provide a method of manufacturing a foot warming
exothermic device and the foot warming exothermic device which
inhibit an exothermic reaction of an exothermic composition and
prevent any possible heat loss due to heat generation during a
manufacturing operation and various harmful effects of quality
degradation and solidification of the exothermic composition; which
enable uniform distribution of the exothermic composition through
the utilization of a transfer/lamination technique, such as
printing, e.g., screen printing, or coating, and can enhance
lamination reliability thereby to stabilize product quality, thus
enabling manufacture of ultra-thin exothermic devices in a simple
way and at a high rate; which enable the fluid exothermic
composition to be uniformly distributed and immobilized within a
pouch by laminating the exothermic composition on a
water-absorbable foamed thin sheet, paper, corrugated board,
cardboard core paper, nonwoven fabric of rayon, for example, woven
cloth, or a porous thin sheet, or on a water absorptive layer
formed on such material, whereby the exothermic composition can be
prevented from movement and displacement; and which enables the
fluid exothermic composition to be prevented from any excessive
exothermic reaction as far as possible through thickness reduction
with respect to the composition.
[0030] It is another object of the invention to provide a method of
manufacturing a foot warming exothermic device and the foot warming
exothermic device wherein a fluid exothermic composition is
transferred onto a wrapper material, e.g., paper, card board, card
board core or nonwoven cloth, such as of rayon, by using screen
printing technique, so that the stage of powder transfer can be
eliminated, which simplifies factory management requirements for
meeting the GMP standards in the manufacture of medical tools and
devices and pharmaceutical supplies in the future.
[0031] The inventor has found that by placing a fluid exothermic
composition on a thin sheet base material, then placing a thin
sheet covering material thereon, the base material and the covering
material being bonded together through the utilization of the
viscosity of the fluid exothermic composition, then cutting out the
resulting laminate to such a shape as to cover a desired
application site, it is also possible to produce an ultra-thin foot
warming exothermic device such that the fluid exothermic
composition is uniformly distributed and immobilized within a pouch
and that any excessive exothermic reaction of the exothermic
composition is prevented as far as practicable.
[0032] The present invention has been developed on the basis of the
foregoing finding, and accordingly it is another object of the
invention to provide a method of manufacturing a foot warming
exothermic device and the foot warming exothermic device wherein
the exothermic device is produced by placing a fluid exothermic
composition on a thin sheet base material, then placing a thin
sheet covering material thereon, at least one of the base material
and the covering material being water absorptive or rendered water
absorptive by a certain treatment, the base material and the
covering material being bonded together through the utilization of
the viscosity of the fluid exothermic composition, then cutting out
the resulting laminate to such a shape as to cover a desired foot
site whereby an exothermic reaction of the fluid exothermic
composition is suppressed, and any possible heat loss due to heat
generation during a manufacturing operation, quality degradation of
the fluid exothermic composition, and various harmful effects of
solidification of the exothermic composition are prevented, and
wherein the device can be produced in the form of an ultra-thin
foot warming exothermic device such that the exothermic composition
is prevented from movement and displacement and that any excessive
exothermic reaction of the exothermic composition is prevented as
far as possible. In order to accomplish the above objects, a first
method of manufacturing a foot warming exothermic device in
accordance with the present invention (hereinafter referred to as
first method of the invention) comprises: placing an exothermic
composition of a viscous fluid by printing or coating on one
surface of a thin sheet base material and in at least one
predetermined portion of said one surface to such a configuration
as to cover an arbitrary site of a human foot, and then placing a
thin sheet covering material on said exothermic composition so as
to cover the exothermic composition, at least one or part of said
base material and said covering material being gas permeable.
[0033] The first method of the invention will now be described in
detail.
[0034] The first method of the invention is characterized in that
the exothermic composition to be used is a fluid exothermic
composition, and not of a powder form as in the prior art.
[0035] The exothermic composition is not particularly limited as
long as it comprises a component which reacts with oxygen in the
ambient air to produce an exothermic reaction and is able to flow
when an external force is applied. That is, there is no particular
limitation with respect to the composition as long as the
composition can be transferred and/or laminated by printing, such
as screen printing, or coating. Such a fluid exothermic composition
can be obtained by regulating the mixing ratio of necessary
components, that is, the ratios of water, a water absorptive
polymer and/or a thickener to other components.
[0036] In the first method of the invention, the use of such fluid
exothermic composition, as the exothermic composition, in
particular provides various advantages as stated below.
[0037] That is, in the first method of the invention, the use of
the fluid exothermic composition much simplifies the process of
lamination by printing, such as screen printing, or coating, and
enables a high-speed production of an ultra-thin foot warming
exothermic device. Further, the method enables a uniform
distribution of the exothermic composition within a pouch. In
addition, when the exothermic composition is laminated on a foamed
thin sheet, paper, nonwoven fabric of rayon or the like, woven
cloth, or on a porous thin sheet, the exothermic composition
exhibits a high anchoring characteristic so that it bites into
pores of the thin sheet, which prevents movement and/or
displacement of the composition.
[0038] In this case, where such a film or sheet has a water
absorptive ability and the exothermic composition is laminated on
the film or sheet, or where a water absorptive layer is formed on
the thin sheet and the exothermic composition is laminated on the
water absorptive layer, the whole or part of the exothermic
composition can be more easily secured to the foamed thin sheet,
paper, nonwoven cloth, woven cloth, or porous thin sheet, or to the
water absorptive layer formed thereon, with the result that the
composition can be prevented more positively from movement or
displacement.
[0039] The use of a lamination technique by way of printing, such
as screen printing, or coating enables production of a very thin
exothermic device. In contrast to prior art exothermic compositions
in powder form, the exothermic composition has an area limited for
contact with air so that the quantity of its heat generation per
unit time is limited. Thus, an excessive exothermic reaction of the
exothermic composition is suppressed. Further, because of the fact
that the exothermic composition is in the form of a fluid and has a
thin layer thickness, any movement and/or displacement of the
exothermic composition itself can be inhibited.
[0040] Furthermore, according to the first method of the invention,
where the exothermic composition is transfer-laminated by printing,
such as screen printing, or coating on a water-absorptive wrapper
material, such as foamed thin sheet, paper, card board, card board
core material, nonwoven fabric of rayon or the like, woven cloth,
or porous thin sheet, the step of powder inputting is eliminated,
and this simplifies the process of plant management to meet the GPM
standards in the manufacture of medical tools and medicaments in
the future.
[0041] In the first method of the invention, the use of the fluid
exothermic composition provides various advantages as mentioned
above. Particularly where, in the preparation of the exothermic
composition, the proportion of water in the exothermic composition
is arranged to be higher and, in addition, a water absorptive
polymer and/or a thickener is mixed into the composition for
adjustment to enable the composition to be formed into a viscous
exothermic composition, the process of transfer/lamination by
printing or coating can be performed very easily and a high-rate
production of an ultra-thin exothermic device can be achieved.
Further, free water or excess water forms barrier layers to
diminish the supply of air, with the result that exothermic
reaction is substantially stopped. This is desirable because
various harmful effects which may otherwise arise from an
exothermic loss during the process of manufacture, quality
degradation of the exothermic composition, and coagulation of the
exothermic composition can be prevented.
[0042] In the prior art exothermic compositions, the proportion of
water is only adequate to allow an exothermic reaction and there is
no moisture-based barrier layer formed on the surface of the metal
powder, more particularly on the surface of iron powder, and
therefore an exothermic reaction progresses smoothly and
continuously through a contact of the composition with air. As
such, an exothermic reaction occurs after the composition is loaded
and before an exothermic device manufactured as such is enclosed in
an outer pouch, there arises a loss due to the exothermic reaction
which results in a quality degradation of the exothermic
composition. In addition, masses produced by the exothermic
reaction coagulate to present various troubles, such as reduced
yield, handling difficulty, troublesome additional jobs affecting
plant maintenance operation, inconveniences caused in relation to
plant operation time and/or operator's working hours, and
inconvenient work involved in coagulated mass treatment.
[0043] In the first method of the invention, there is no particular
limitation with respect to the method for depositing a viscous
exothermic composition on the base material. Preferably, however,
the composition be deposited by using known printing techniques,
for example, thick-film printing, gravure printing, offset
printing, screen printing, or spraying, or by coating or
transferring by means of a head coater, a roller, and/or an
applicator.
[0044] Any conventional exothermic composition has a wetting
characteristic given through its water content, but the proportion
of the water therein is only adequate to enable thermal reactions.
Therefore, the composition has only poor fluidity, which makes it
extremely difficult to allow the composition to be uniformly
distributed within a predetermined area on the base material by a
mere throw-down placement.
[0045] In contrast, according to the first method of the invention,
a thickener is added to the exothermic composition in preparing the
exothermic composition so that the composition has a viscous
characteristic. The exothermic composition can be easily
transferred by printing, such as screen printing, or coating, and
enables a high-rate production of the ultra-thin exothermic device.
Furthermore, any free moisture and excess water present forms
barrier layers to diminish the quantity of air supply, so that
there is almost no possibility of an exothermic reaction being
allowed to occur.
[0046] Where the proportion of water is relatively high in the
exothermic composition so that the free moisture and excess water
present therein form barrier layers, part of the water content of
the exothermic composition may be absorbed by the base material
and/or a wrapper material, such as a covering material, or by a
water absorptive layer formed on the base material and/or the
covering material. Then, the barrier layers will go out of
existence and any inconvenience due to excessive water can be
eliminated.
[0047] In the first method of the invention, the exothermic
composition which constitutes the exothermic composition comprises,
as essential ingredients thereof, water, a water absorptive
polymer, a thickener, and other materials, that is, materials other
than those essential for exothermic reaction, including a carbon
component, such as carbon or activated charcoal, for promoting heat
generation, and a metal chloride for fracturing an oxide film on
the surface of a metal powder and continuously generating an
exothermic reaction. Where so desired, an inorganic or organic
water retainer, a pH adjustor, a surface active agent for
dispersability enhancement, and/or an anti-foaming agent may be
compounded into the composition. Thus, the exothermic composition,
in its entirety, is in the form of a fluid.
[0048] The proportions-of various ingredients of the exothermic
composition may vary depending upon the type of the water
absorptive polymer, the types of the exothermic materials and
carbon component, and the type of the metal chloride, but generally
it is desirable that the water absorptive polymer be within the
range of from 0.05 to 7.5 parts by weight relative to 100 parts by
weight of the exothermic materials, the thickener from 0.05 to 10
parts by weight, carbon component from 1.5 to 20 parts by weight,
and the metal chloride from 1 to 10 parts by weight. In the first
method of the invention, water is added to a mixture of the above
ingredients so that the entire mixture is rendered pasty. In this
case, a predetermined amount of the metal chloride may be dissolved
or dispersed in water, the resulting solution or dispersion being
added to a mixture of the water absorptive polymer, thickener and
carbon component to provide a composition in the form of paste as a
whole.
[0049] In the first method of the invention, the exothermic
composition, prepared in the form of a fluid as stated above,
generally has a viscosity range (at 20.degree. C.) of preferably
from 50,000 to 6,500,000 cps as measured according to a method
described hereinafter.
[0050] If the viscosity of the fluid exothermic composition is too
low or less than 50,000 cps, the exothermic composition has poor
transferability by printing or coating, an excessive water content
which results in a shortage of transfer of other ingredients and a
reduced duration of heat generation. Further, the low degree of
viscosity results in a separation of the metal powder such as iron
powder which makes it difficult to maintain the uniformity of the
ingredients, and oozing of part of the fluid exothermic composition
out of the predetermined site on the base material. In addition,
such a low degree of viscosity may necessitate a large amount of
moisture to be absorbed by the base material and/or the covering
material after the process of transfer operation, the use of a base
material and/or covering material of a special construction, and a
complicated structure design for the exothermic composition. If the
viscosity is more than 6,500,000 cps, the transferability of the
composition is adversely affected, resulting in varied quantities
of transfer and generation of exothermic reaction on the
surface.
[0051] The viscosity herein means a value measured as such at a
temperature of 20.degree. C. by using a viscometer (Model BH) made
by TOKIMEC INC. , with a #7 rotor run at a rotational speed of 2
rpm, and using in conjunction therewith a beaker having an inner
diameter of 85 .o slashed.mm.
[0052] In the first method of the invention, where the fluid
exothermic composition, as described above, comprises water, a
water absorptive polymer, a thickener, and other materials
including an exothermic material, a carbon component and a metal
chloride, the composition exhibits the desired heat generating
characteristic. However, where it is desired to achieve further
improved temperature stability and further improvement in the
duration of heat generation, an inorganic or organic water
retainer, a pH adjustor, a surface active agent for dispersibility
enhancement, and/or an anti-foaming agent can be advantageously
loaded into the composition to produce a useful exothermic
composition in a fluid form as a whole.
[0053] That is, it is preferable to use the water absorptive
polymer within the range of from 0.05 to 7.5 parts by weight, the
thickener from 0.05 to 10 parts by weight, the carbon component
from 1.5 to 20 parts by weight, the metal chloride from 1 to 10
parts by weight, the inorganic or organic water retainer from 0.5
to 10 parts by weight, the pH adjustor from 0.1 to 5 parts by
weight, the surface active agent for dispersibility enhancement
from 0.1 to 5 parts by weight, and the defoaming agent from 0.1 to
5 parts by weight, relative to 100 parts by weight of the heat
generating materials. In the first method of the invention, the
mixture in particular is added with water so that the resulting
composition in its entirety is in the form of a fluid. In this
case, the metal chloride may be dissolved or dispersed in a
predetermined quantity of water, the resulting solution or
dispersion being added into a mixture consisting of the water
absorptive polymer, the thickener, the carbon component, the
inorganic or organic water retainer, the Ph adjustor, the surface
active agent, and the defoaming agent, whereby the mixture as a
whole is rendered pasty in its form.
[0054] In this case, too, as above stated, generally, the viscosity
of the exothermic composition is preferably within the range (at
20.degree. C.) of from 50,000 to 6,500,000 cps as measured
according to the above described method.
[0055] Water absorptive polymers useful in the first method of #he
invention are typically polymeric materials which can absorb water
and/or an aqueous solution of a metal chloride smoothly and in a
large amount, specifically, for the water absorptive polymer is
used one kind of material or a mixture of two or more kinds of
materials as selected, for example, from the group consisting of
starch polyacrylonitrile copolymers disclosed in Japanese Patent
Publication No. 49-43395, cross-linked polyalkylene oxides
disclosed in Japanese Patent Publication No. 51-39672, vinyl
ester-ethylene unsaturated carboxylic acid copolymer saponification
products, self-crosslinked polyacrylates as produced by a reversed
phase suspension polymerization method disclosed in Japanese Patent
Publication No. 54-30710, reaction products of a polyvinyl alcohol
polymer and a cyclic anhydride as disclosed in Japanese Patent
Application Laid-Open No. 54-20093, cross-linked polyacrylates
disclosed in Japanese Patent Application Laid-Open No. 59-84305,
and a cross-linked N-vinyl acetamide (water absorptive agent
manufactured by Showa Denko K. K.; trade name: NA-Ob). These
materials may be treated with or used in combination with a surface
active agent for improvement of their hydrophilic characteristic.
Some of these water absorptive polymers can absorb water and/or an
aqueous solution of chloride to provide a thickening effect, but
their main function is to absorb water and/or an aqueous metal
chloride liquid smoothly and in a large amount.
[0056] For the water absorptive polymer, commercially available
polymers of the kind may be used including, for example, products
of Sanyo Kasei K. K., such as Sanwet IM-300, Sanwet IM-300MPS,
Sanwet IM-1000, Sanwet IM-300MS, and Sanwet IM-lOOOMPS; products of
Seitetsu Kagaku K. K., such as Aquakeep 4S and Aquakeep 45H;
products of Sumitomo Kagaku K. K., such as Sumikagel NP-1020,
Sumikagel NP-1040, Sumikagel SP-520, and Sumikagel N-1040; products
of Kurare K. K., such as KI GEL 201-K and KI GEL 201K-F2; and
products of Arakawa Kagaku K. K., such as Arasoap 800 and Arasoap
800F.
[0057] Especially preferred of these commercially available water
absorptive polymers are Sanwet IM-300MPS and Sanwet IM-1000MPS
manufactured by Sanyo Kasei K. K.; Sumikagel NP-1020 and Sumikagel
NP-1040 manufactured by of Sumitomo Kagaku K. K.; KI Gel 201-K and
KI Gel 201-F2 manufactured by Kurare K. K.; and Arasoap 800F
manufactured by Arakawa Kagaku K. K., all of these being capable of
quick and high absorption of water and an aqueous metal chloride
liquid.
[0058] Thickening agents useful in the first method of the
invention are typically materials which can absorb water and/or an
aqueous solution of a metal chloride thereby to enhance cone
penetration or impart a thixotropic characteristic to the
composition. Specifically, for the thickener is used one kind of
material or a mixture of two or more kinds pf materials as
selected, for example, from among polyacrylates, such as bentonite,
stearate, and soda polyacrylate; alginates, such as gelatin,
polyethylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone,
tragacanth gum, locust bean gum, gum guar, guam arabic, and soda
alginate; starch-based water absorptive agents, such as pectin,
carboxyvinyl polymer, dextrin, alpha starch, and processing starch;
polysaccharide-based thickening agents, such as carrageenan and
agar; cellulose derivative-based thickening agents, such as CMC,
ethyl cellulose acetate, hydroxyethyl cellulose, methyl cellulose,
and hydroxypropyl cellulose; acrylosulfonic acid-based polymeric
materials (e.g., "CS-6H5", manufactured by Nippon Khokubai K.K.);
and water-soluble cellulose esters and poly-N-vinyl acetoamides.
These materials may be treated with or used in combination with a
surface active agent for improvement of their hydrophilic
characteristic. These water absorptive polymers can absorb water
and/or an aqueous solution of metal chloride to enhance cone
penetration and provide a thixotropic effect.
[0059] Specific examples of above mentioned water-soluble cellulose
ethers are varieties of methyl cellulose produced by etherifying a
cellulose with a methoxyl group (Metolose SMiS, Metolose SM25,
Metolose 5M400, and Metolose SM4000, manufactured by Shin-Etsu
Kagaku Kogyo K. K.); varieties of hydroxypropylmethyl cellulose
produced by etherifying cellulose with a hydroxypropoxyl group
(Metolose 60SH-50, Metolose 60sH-4000, Metolose 90SH-4000, Metolose
90SH-3000, and Metolose 90SH-100O00), and varieties of
hydroxymethyl cellulose produced by etherifying cellulose with a
hydroxyethoxyl group (made by Shin-Etsu Chemical Co.; trade names
"Metolose 60SH-50, Metolose 605H-4000, Metolose 90SH-4000, Metolose
905H-3000, and Metolose 90SH-100000, manufactured by Shin-Etsu
Kagaku Kogyo K. K.).
[0060] When an aqueous solution of such a water-soluble cellulose
ether is heated up to, for example, a predetermined temperature
(thickening start temperature), the viscosity of the solution is
lowered. When further heated to a higher temperature, the adsorbed
moisture is released so that the solution gains an increase in its
viscosity to go into the state of a gel (this phenomenon is
hereinafter referred to as gelation). The liberated moisture forms
barrier layers to diminish an exothermic reaction. Whilst, when the
gel is cooled, it adsorbs moisture to return to its original
state.
[0061] The thickening start temperature of a water-soluble
cellulose ether is influenced by the type of the etherifying agent,
the degree of substitution, the molecular weight of the cellulose,
and where the cellulose ether is added in the form of a solution,
by the concentration thereof, and where other additive is added, by
the type of the additive and the amount of addition (concentration)
and also by the rate of temperature rise and the rate of cooling.
Therefore, when a water-soluble cellulose ether is used as a
thickening agent, the type of an etherifying agent, the degree of
substitution, the cellulose molecular weight, the concentration of
the solution, and the type of other additive and the amount of
addition (concentration) thereof, as well as the make-up of the
exothermic composition and the intended amount of use thereof, are
suitably selected to control the rate of temperature rise and the
rate of cooling thereby to suitably select a maximum heat
generation temperature.
[0062] In the case of a 2 wt % aqueous solution of 8 water-soluble
cellulose ether (e.g., Metolose SM4000 manufactured by Shin-Etsu
Kagaku Kogyo K. K.), for example, where no additive is involved,
the thickening start temperature is 55.degree. C., but when 5 wt %
of sodium chloride (NaCl) or 5 wt % of sodium carbonate
(Na2CO3.10H2O) is added, the thickening start temperature is
40.degree. C. When the device is applied directly to a human body,
the Metolose SM4000 releases an adsorbed moisture at not more than
a safety temperature (43.degree. C.) thereby to inhibit an
exothermic reaction.
[0063] Where 5 wt % of A12(S04).18H2O is added, the thickening
start temperature of Metolose SM4000 is still 45.degree. C., and at
this temperature, Metolose 5M4000 releases an adsorbed moisture
around the metal powder to inhibit the exothermic reaction.
[0064] In the case of a 2 wt % aqueous solution of a water-soluble
cellulose ether (e.g., Metolose 60SH-4000), for example, if there
is no additive present therein, the thickening start temperature is
75.degree. C., but when 5 wt % of sodium chloride (NaCl) is added,
the thickening start temperature is 70.degree. C., and When 5 wt %
of sodium carbonate is added, the thickening start temperature is
45.degree. C. At these temperatures, Metolose 60SH-4000 releases an
adsorbed moisture around the metal powder to inhibit the exothermic
reaction.
[0065] Where 5 wt % of A12(S04).18H20 is added, the thickening
start temperature of Metolose 60SH4000 is 50.degree. C., and at
this temperature, Metolose 605H-4000 releases an adsorbed moisture
to increase the amount of free water around the metal powder
thereby to inhibit the exothermic reaction.
[0066] Additives useful for adjusting the thickening start
temperature of the above mentioned thickener are, for example,
above mentioned sodium chloride and sodium carbonate, inorganic
matter, such as aluminum sulfate hydrates, a lower alcohol, such as
ethanol, polyvalent alcohols, such as polyethylene glycol and
glycerine, and above mentioned water absorptive polymers and
thickening agents.
[0067] The poly-N-vinylacetoamide is a material obtained through
radical polymerization of N-vinylacetoamide. There are two types,
one having a straight-chain structure which is water-soluble, and
the other having a cross-linked structure which is water-insoluble.
An example of the water-insoluble poly-N-vinylacetoamide is a
microgel which functions as a gelling agent through the difference
in crosslink density. Specifically, for the poly-N-vinylacetoamide
is used one kind of material or a mixture of two or more kinds of
material as selected from among, for example,
N-vinylacetoamide-sodium acrylate copolymer (GE-167, manufactured
by Showa Denko K. K.), N-vinylacetoamide homopolymer (GE-191,
manufactured by Showa Denko K. K.), and N-vinylacetoamide
cross-linked material (microgel) (GX-205, manufactured by Showa
Denko K. K.). These materials may be treated with or used in
combination with a surface active agent for improvement of their
hydrophilic characteristic. These water absorptive polymers can
absorb water and/or an aqueous solution of metal chloride to
enhance cone penetration and provide a thixotropic effect.
[0068] Of course, the water absorptive polymer and the thickener
cannot strictly be discriminated from each other. The water
absorptive polymer and the thickener are preferably such that they
repeat absorption and release of water with variations in
temperature thereby to enable temperature control.
[0069] While it is possible to use organic matter as exothermic
material in the first method of the invention, metal powders which
do not generate offensive odor as a reaction progresses are used
including iron powder, zinc powder, aluminum powder, and magnesium
powder, or powder of an alloy comprised of two or more kinds of
such metals, or a mixture powder of such metal powders. Of these
metal powders, iron powder in particular is preferably used when
all such factors as safety, ease of handling, cost, keeping
quality, and stability are considered. For the carbon component,
carbon black, graphite, and activated carbon may be exemplified as
such, and for the metal chloride, alkali metal chlorides, such as
sodium chloride and potassium chloride, and alkali earth metal
chlorides, such as calcium chloride and magnesium chloride, may be
exemplified as such.
[0070] The inorganic or organic water retainer is an agent for
retaining water such that not only does it function to release
water when the exothermic reaction slows down, it acts to increase
voids in the exothermic composition thereby to enable a favorable
contact between the ambient air and the exothermic composition.
[0071] Specific examples of such water retainer are perlite,
cristobalite, vermiculite, siliceous porous substances, silicates,
such as calcium silicate, siliceous earth substances, such as
silica, diatom earth, and alumina, mica powder, clay, magnesium
oxide, such as talc, etc., silica powder, wood powder, and pulp
powder.
[0072] For the pH adjustor, surface active agent, and defoaming
agent, a conventional pH adjustor, such as sodium polyphosphate,
and other materials used in the art are used as such.
[0073] In the fluid exothermic composition, where an excess water
is present, part of the water may be caused to be absorbed by the
base material and/or the covering material.
[0074] It is desirable that the base material and/or the covering
material should have a water absorbing characteristic. However,
materials having a water absorbing characteristic are not
particularly limited as long as the material is water-absorbable
and has a thin sheet configuration. Specific examples of such
material are foamed thin sheet, paper, card board, card board core
material, nonwoven fabric of rayon or the like, woven cloth, or
porous thin sheet.
[0075] In the first method of the invention, the base material and
the covering material may be basically of the same type, but since
the exothermic composition which generates heat through its contact
with air is the heat source of the device, it is required that at
least one or part of the base material and the covering material
must be gas permeable.
[0076] In the formation of such an ultra-thin exothermic device, if
any further thickness reduction (to a thickness of about 1 mm or
less) and weight reduction are intended, there will occur a
decrease in the quantity of exothermic reaction per unit hour.
Therefore, only with a pressure reduction based on the consumption
by the exothermic composition of oxygen in the air within the
pouch, it may not necessarily be possible to maintain such a
condition of reduced pressure as is sufficient to prevent any
movement and/or displacement of the exothermic composition. In such
a case, it is desirable that the whole or part of the exothermic
composition be fixed to the base material and/or the covering
material so that the exothermic composition can be prevented from
movement and/or displacement Specifically, where the base material
and/or the covering material has a smooth surface, for example, it
is desirable that a concave-convex portion be physically formed on
the surface at least at a site of contact with the exothermic
composition, or a water absorber having a water absorbing
capability be laid on one side or both sides of the base material
and/or the covering material thereby to form a concave-convex
portion at a site of contact of the base material and/or the
covering material with the exothermic composition. Thus, the bond
of the base material and/or the covering material with the
exothermic composition can be increased to prevent the exothermic
composition from movement and/or displacement because of the
adhesion resulting from water absorption from the exothermic
composition and the concave/convex portion formed as shown
above.
[0077] The water absorber is not particularly limited as long as
the water absorber, whether or not its material has a water
absorption characteristic, is in effect water absorptive. Specific
examples of the water absorber is one comprised of foamed sheet,
paper, card board, card board core material, nonwoven fabric of
rayon or the like formed of water absorptive fibers, woven cloth,
or a porous thin sheet; one comprising a foamed thin sheet, paper,
nonwoven cloth, woven cloth, or a porous thin sheet which is made
to contain or carry a water absorbing agent by impregnation,
loading, or transfer thereby so as for it to have a water absorbing
characteristic; and one comprising a combination of a foamed film
sheet, paper, nonwoven cloth, woven cloth, or porous thin sheet and
a water absorptive foamed thin sheet, paper, nonwoven cloth, woven
cloth, or a porous film/sheet cut to a planar configuration of the
exothermic composition, the combination being placed on the
exothermic composition to obtain a water absorbing
characteristic.
[0078] In the first method of the invention, since the base
material and/or the covering material is formed, at least at a site
of contact with the exothermic composition or at water absorbers,
with a water absorptive layer which is made to contain or carry a
water absorbing agent by impregnation, loading, or transfer, it is
desirable to embed the whole or part of the exothermic composition
in the concave/convex portion and/or the water absorptive layer
thereby to prevent any movement or displacement of the exothermic
composition.
[0079] In the first method of the invention, in order that any
movement or displacement of the exothermic composition may be more
positively prevented, it is desirable that at sites of contact with
the exothermic composition in both the base material and the
covering material there should be formed concave/convex portions
and/or water absorptive layers, so that part of water in the
exothermic composition, that is, excess water may be absorbed
through the concave/convex portions into the base material and/or
the covering material.
[0080] Since the movement of the exothermic composition within the
pouch is prevented in this way, the exothermic composition can be
prevented from being displaced toward one side, with the result
that variations in heating temperature and generation of an
abnormally high heat are inhibited.
[0081] In the case where the surface of the base material and/or
the covering material is smooth, the method to be employed for
roughing (to form concavities and convexities on) the surface of
the base material and/or covering material is not particularly
limited. Specifically, however, it is desirable to roughen the
surface (to form concavities and convexities thereon) by a physical
treatment, for example, a corona treatment thereby to enable the
surface to exhibit a wetting index of at least dyne or more,
preferably 40 dyne or more.
[0082] In the first method of the invention, where at least the
site for contact with the exothermic composition in the base
material and/or the covering material is formed with a roughened
surface or a concavity and a convexity and/or with a water
absorptive layer, the base material and/or the covering material,
if it is formed of a water absorptive material, the roughened
surface or concavity/convexity functions to prevent the
displacement or movement of the exothermic composition, and the
water absorptive layer also functions to prevent the movement or
displacement of the exothermic composition, whereby a synergistic
effect can be obtained in more positively preventing the movement
or displacement of the exothermic composition. Furthermore, part of
the water in the exothermic composition, that is, excess water is
allowed to be absorbed by the base material and/or the covering
material.
[0083] Where a water absorptive layer is formed in the base
material and/or the covering material at a site for contact with
the exothermic composition, other ingredients than water of the
exothermic composition are attracted by the water-absorbing force
of the water absorptive layer toward the base material and/or the
covering material, and part of such ingredients wets out on the
water absorptive layer to produce a powerful anchor effect. In that
case, therefore, any particular surface roughing treatment is
unnecessary.
[0084] For the water absorptive agent, aforementioned water
absorptive polymers and thickeners are exemplified as such.
Therefore, the water absorptive layer is a layer formed of any of
those polymers or thickeners.
[0085] As already stated, the base material and/or covering
material used in the first method of the invention embraces such a
material of a single layer construction and one comprised of plural
layers laminated one over another in the direction of thickness of
the layer.
[0086] In the above connection, the expression "laminated" means
that individual layers are wholly or partially bonded together by
lamination or otherwise, and also that individual layers are simply
laid one over another and, at a local site, such as a peripheral
edge portion or a central portion, they are joined together by heat
setting, bonding, adhesion, hot fusion bonding, or lamination.
[0087] Where the base material and/or the covering material is of a
single layer construction (single film or sheet), as earlier
described, in order to prevent movement and/or displacement
thereof, it is desirable that the surface of the thin sheet, if
flat and smooth, be roughened (concave-convex surfaced), or a
foamed thin sheet, paper, nonwoven fabric, woven fabric or porous
thin sheet be used as the thin sheet. Where these are
water-absorbable materials such that the material is comprised of
water-absorbable fibers, for example, such material may be caused
to contain or incorporate by way of impregnation, transfer,
lamination, or loading thereby to exhibit a water absorption
behavior. In this case, use of a foamed thin sheet such as sponge,
nonwoven fabric or woven fabric will provide good adhesion with an
adhesive layer to be described hereinafter. Where the base material
comprises plural layers, that is, two or more layers of the thin
sheet laminated together, the earlier noted ones may be mentioned
as typical examples.
[0088] Both the base material and the covering material must have
necessary mechanical strength characteristics such as tensile
strength, and preferably they are flexible as a whole to provide
improved conformability in relation to foot surface.
[0089] Therefore, the base material and the covering material may
vary considerably in thickness depending upon the intended use and
are not particularly limited in thickness. Specifically, the
thickness is generally in the range of from 5 to 5000 .mu.m or so,
and where the device is applied directly to the user's foot, a
preferred thickness range is from 10 to 1500 .mu.m, more preferably
from 20 to 1000 .mu.m. For general use, a thickness range of from 5
to 2500 .mu.m is preferred, more preferably from 10 to 2000
.mu.m.
[0090] A thickness of less than 5 .mu.m with respect to the base
material and the covering material is undesirable because it does
not provide necessary mechanical strength and may make it difficult
to equalize the layer thickness. Where the thickness of the base
material and of the covering material exceeds 5000 .mu.m, these
materials are of low flexibility even if they are comprised of a
foamed material such as sponge, and their conformability in
relation to the surface of the user's foot is exceptionally low.
Further, they feel rough and present unfavorable hand. A further
inconvenience of such a layer thickness is that the foot warming
exothermic device as a whole becomes excessively thick.
[0091] Therefore, it is particularly preferable that both the base
material and the covering material are within a thickness range of
from 15 to 1000 .mu.m, because this thickness range provides
necessary mechanical strength and good flexibility.
[0092] The base material and the covering material may be a foamed
or non-foamed thin sheet formed from a polymeric material. Where a
foamed thin sheet is used, the exothermic composition can be caused
to bite into the thin sheet, being thereby prevented from movement
and displacement.
[0093] Examples of the component polymeric material of such thin
sheet are polyethylene, polypropylene, polyamide, polyester,
polyvinyl chloride, polyvinylidene chloride, polyurethane,
polystyrene, saponified ethylene-vinyl acetate copolymer, and
ethylene-vinyl acetate copolymer.
[0094] For enabling the non-foamed thin sheet formed of a polymeric
material to have gas permeability, a number of methods can be used
including a method such that vents are formed through a drawing
operation during the process of forming the sheet, another method
such that vents are formed by extracting a particular ingredient
from the thin sheet, and a further method such that after the thin
sheet is formed as such, vents are mechanically formed by a
piercing operation such as punching and needling. A porous thin
sheet can be obtained by any of these methods.
[0095] There are different types of foamed thin sheets comprised of
a polymeric material, including foamed thin sheets of the type
having closed cells or open cells formed by foaming which are open
on opposite surfaces; those of the type in which after the process
of foaming, the thin sheet is pressed whereby closed cells or open
cells formed therein are fractured to be enabled to communicate
with the opposite surfaces, the thin sheet being thus made gas
permeable; and those of the type having no gas permeability and
remaining gas-tight even after being foamed.
[0096] Paper and cloths such as woven cloths, knitted cloths, and
nonwoven cloths are gas permeable because they are of such a
construction that they have vent pores and/or vent paths formed
therein which communicate with opposite surfaces. Fibers usable as
component fibers of such cloths include, for example, natural
fibers, regenerated fibers using natural fiber materials such as
viscose fibers, semi-synthetic fibers, synthetic fibers, and
mixtures of two or more kinds of these fibers.
[0097] The natural fibers include vegetable fibers such as cotton
and hemp, and animal fibers such as silk and animal hair. Polymeric
materials as components of the synthetic fibers include, for
example, polyethylene, polypropylene, polyamide, polyester,
polyvinyl chloride, polyvinylidene chloride, polyurethane,
polystyrene, saponified ethylene-vinyl acetate copolymer, and
ethylene-vinyl acetate copolymer.
[0098] In the first method of the invention, in order to enable the
foot warming exothermic device to be more suitably applied to the
user's foot at a curved portion, an extensible portion, and/or a
flexing portion thereof, and to more readily conform to the
movement of the extensible portion and also of the flexing portion,
it is desirable that the base material and covering material, that
is, the wrapper of the device, is formed of an extensible material,
more particularly a stretchable material.
[0099] In other words, where the base material and covering
material, that is, the wrapper is formed from an extensible
material, more particularly a stretchable material, the wrapper
exhibits good stretch/shrink characteristics such that it can more
easily conform to the movement of various portions of the user's
foot, such as curved portion, stretchable portion, and flexing
portion, while keeping good contact therewith. Further, the wrapper
does not feel stiff, nor does it give any unharmonious feel, thus
enabling the device to give a comfortable feel when it is used.
Moreover, separation during the use of the device can be positively
prevented, which results in improved heating effect.
[0100] Examples of such extensible materials suitable for use as
the base material and covering material are materials formed of
synthetic resins having high extensibility, such as polyethylene
and polypropylene.
[0101] Stretchable materials for the base material and covering
material, that is, stretchable thin sheets, are not particularly
limited as long as the thin sheets are formed from materials having
stretch/shrink characteristics. Specifically, however, typical
examples of such materials are foamed thin sheets, nonwoven cloths,
woven cloths, or porous thin sheets which have stretch and shrink
characteristics and high adaptation for bond with the exothermic
composition. These materials are preferred as long as they have a
water absorptive ability, or if they are provided with a water
absorptive ability or improved water absorptive ability by having
been caused to contain, incorporate or carry by impregnation,
deposition, loading, or transfer, whether or not they have a water
absorptive ability. The reason is that such material is operative
to absorb an excess water in the exothermic composition to
eliminate any barrier layers thereby to keep the exothermic
composition in a favorable condition.
[0102] Materials suitable for stretchable thin sheets include, for
example, natural rubber, synthetic rubber, and thermoplastic
elastomers. Thermoplastic elastomers are preferred inter alia
because they have high stretch/shrink characteristics, are easy to
handle, and have hot fusion bonding properties, which can
facilitate the manufacture of the exothermic device.
[0103] In the first method of the invention, of course,
irrespective of whether or not the base material and covering
material have adhesivity, and hot fusion or hot welding properties,
it is desirable that the base material and the covering material be
sealingly secured around the exothermic composition by adhesion,
hot fusion bonding, or heat bonding. Specific examples of the
synthetic rubber are butadiene rubber, isoprene rubber,
styrene-butadiene rubber, acrylonitrile-butadiene rubber,
chloroprene rubber, isobutylene-isoprene rubber, polyalkylene
sulfide, silicone rubber, poly(chlorofluoroethylene)1 vinylidene
fluoride-6 propylene fluoride copolymer, urethane rubber, propylene
oxide rubber, epichlorohydrin rubber acrylate-acrylonitrile
copolymer, and acrylate-2-chloroethyl vinyl ether copolymer.
[0104] Specific examples of the thermoplastic elastomer are
olefinic elastomers, polyurethane elastomers, and polyester
elastomers.
[0105] Specific examples of the olefinic elastomers are
ethylene-propylene copolymer, ethylene-propylene-diene terpolymer,
chlorosulfonated polyethylene, chlorinated polyethylene, and
ethylene-vinyl acetate copolymer.
[0106] In addition to the case where a foot warming exothermic
device is applied in direct contact with the user's foot, sometimes
there may be cases where such a device is used through application
to the exterior of a sock or application to the sole of a shoe.
Therefore, unlike other types of exothermic devices which are
applied to other sites, such as the waist, of a human body, the
foot warming exothermic device is subject to considerable
variations in the condition of air supply to the device depending
upon the condition in which the device is applied and the condition
of use, e.g., use during walking or while the shoe remains off.
[0107] That is, the foot warming exothermic device is subject to
variations in the force of pressure which is applied thereto by
walking and otherwise so that, where the wrapper is formed from a
foamed material such as sponge, the space within the wrapper itself
is increased or decreased accordingly. As a result, a kind of
pumping action occurs such that the quantity of air feed to the
exothermic composition tends to become greater than that in the
case of exothermic devices for application to other sites of a
human body.
[0108] Therefore, the moisture permeability of the wrapper may be
limited to a lower level than that of a wrapper for other types of
exothermic devices for application to other sites than the foot.
Thus, the wrapper may be comprised of a single-sided thin sheet
having gas permeability, or may be so constructed as to have gas
permeability with respect to only part of the both sides or one
side thereof.
[0109] Then, if it is feared that the interior temperature of the
exothermic device itself might rise too high to cause a low
temperature burn, it is desirable that the water absorptive polymer
and/or thickener should release moisture retained therein to form
barrier layers or the like to suppress an exothermic reaction
thereby to lower the temperature. Conversely, if the interior
temperature of the exothermic device itself drops to the extent
that the desired warming effect cannot be obtained, it is desirable
that the water absorptive polymer and/or thickener be allowed to
absorb free moisture to eliminate the barrier layers thereby to
provide good contact with air.
[0110] In the first method of the invention, it is required that at
least one or part of the base material and covering material must
be gas permeable. Gas permeability has great bearing upon the
control of reaction rate of the exothermic composition and/or of
exothermic temperature and, therefore, control of gas permeability
is desired in order to obtain effective warming effect and to
prevent any low temperature burn to secure safety. For high
precision control of gas permeability it is desirable to control
film gas-permeability on the basis of moisture permeability.
Specifically, the moisture permeability should be within a range of
from 50 to 10,000 g/m.sup.224 hr, more particularly from 100 to
5,000 g/m.sup.224 hr, in accordance with the ASTM method (E-96-80D
Method).
[0111] A moisture permeability of less than 50 g/m.sup.224 hr is
undesirable because the quantity of heat generation obtainable is
too small to provide sufficient warming effect. A moisture
permeability of more than 10,000 g/m.sup.224 hr is also
undesirable, because it will cause an excessive rise in exothermic
temperature which may lead to a low temperature burn. Therefore,
the moisture permeability range of from 100 to 5,000 g/m.sup.224 hr
with respect to the gas permeable thin sheet is particularly
preferred, because this moisture permeability range enables heat
generation of fine optimum temperatures which provide sufficient
warming effect and at which there is no danger of low temperature
burn.
[0112] Method of constructing the base material or covering
material in such a way that part of the material has gas
permeability is not limited to any particular method. For this
purpose, however, in the case where the base material or covering
material which is gas permeable is of a single layer, for example,
the base material or covering material may be partially sealed with
adhesive over the surface thereof, or in the case where the
gas-permeable base material or covering material is of the
laminated type, separately provided partial pieces of a thin sheet
may be laminated over the material to partially cover such
pores.
[0113] In the first method of the invention, the use of a fluid
exothermic composition enables lamination of a layer by transfer,
printing, spraying, coating or the like to a thin sheet thickness
of the order of, for example, from 0.02 to 1.5 mm, preferably from
0.1 to 1.00 mm, further enabling lamination of individual layers to
a uniform thickness. This provides for the realization of high
speed processing, high precision control of the deposited areas,
thin sheet oriented production, and equalization of film
thickness.
[0114] In this case, the fluid exothermic composition performs a
function similar to that of adhesive in joining the base material
and the covering material together and, therefore, the materials
need not necessarily be sealingly bonded around the exothermic
composition. However, in order to further improve the quality and
reliability of the foot warming exothermic device, it is desirable
that the base material and the covering material be sealingly
bonded by heat bonding, adhesion, or hot fusion bonding around the
fluid exothermic composition.
[0115] In the first method of the invention, the predetermined area
in which the fluid exothermic composition is placed by lamination
may be configured to cover a desired site of a foot. Examples of
such a site include part of the sole of a foot; the whole of the
sole; part of the instep of the foot; the whole of the instep; part
or the whole of the sole or instep and part or the whole of a side
portion of the foot; and part or the whole of the sole of the foot,
part or the .about.whole of a side portion, and part or whole of
the instep.
[0116] Examples of part of the sole of the foot include toes, base
of the toes, ball of the foot, plantar arch, and heel. Examples of
the configuration of a foot warming exothermic device covering the
sole of the foot are semicircle and semi-ellipse. Examples of the
configuration of base material and covering material for covering
the base of the toes, ball of the foot, plantar arch and heel are
rectangle, square, trapezoid, oval, ellipse, circle, semi-ellipse,
and horseshoe.
[0117] For covering the entire sole of the foot, the device may be
configured like an inner sole cover of a shoe. Another example of
covering configuration may be that a bulge corresponding to the
plantar arch portion of the inner sole cover protrudes from a
compressed portion of the inner sole cover which corresponds to the
plantar arch of the foot.
[0118] In this case, for example, it may be understood that the
plantar arch has a certain height when viewed from side. Therefore,
the configuration of an exothermic device which covers the entire
sole of the foot may be considered to be a configuration that
covers the sole of the foot to be described hereinbelow, more
particularly the whole plantar portion of the foot sole and part of
sides of the foot. An example of the configuration of an exothermic
device which covers part or the whole of the sole and part of side
portion of the foot may be a configuration such that the device
covers the whole of the sole and a portion extending from the sole
around the heel and up to the ankles, more particularly a portion
extending rearward of the ankles. In this case, the device may be
so formed as to have such a configuration that the portion
corresponding to the sole is shaped like an inner sole cover and
that the portion covering that portion of the foot which extends
around the heel toward the ankles, that is, the portion extending
rearward of the ankles, comprises a bulge formed in continuation to
the portion of the inner sole cover shape. The base material and
covering material are readily deformed to conform to the bulged
contour of the heel in response to the bulge of the heel.
[0119] Where the base material and covering material have
extensibility and/or stretch-shrink characteristics, the base
material and covering material are readily deformed to well conform
to the bulge of the heel, for example, by becoming partially
extended in corresponding relation to the bulge. In this way, the
base material and covering material are well deformable so as to
conform to complex concave/convex configuration of the foot,
exhibiting improved conformance to configurational changes.
[0120] To cover part or the whole of the sole and part or the whole
of side portions of the foot, the device may have a configuration
such that it covers the whole of the sole or the back of the toe
portion and a portion of the foot which extends therefrom and
around the toe portion and up to the instep side portion of the
toes. In addition, the device may take a tabi-like configuration or
a sock-like configuration.
[0121] The configuration of the device in which the device covers
the whole of the sole or the back of the toe portion and a portion
extending therefrom and around the toe portion and up to the instep
side portion of the toes is, for example, such that the device has
a bulge portion formed in continuation to the inner sole cover-like
portion which covers the whole of the sole, the bulge portion
covering the toe portion and the instep side portion of the toes.
In this case, the bulge portion extends in conformity to
depressions and projections of the toes and irrespective of
difference in size of such depressions and projections whereby the
bulge portion is deformed to intimately follow the complex
irregularities of the toes.
[0122] The "tabi" configuration or sock configuration may be one
such that a sock divided symmetrically into two parts continued
with each other along a center line of the bottom is folded
centrally of the bottom after lamination is effected and portions
extending from the toe through the instep to the ankles are joined
at edges thereof with edges of portions extending from the heel to
the ankles. Another configuration example may be such that a
portion of the sock extending from the ankles toward the toe is
divided into two parts which are connected centrally of the bottom
to each other, and a bulge is formed in continuation centrally with
a rear end portion of the bottom for covering the heel up to the
ankles. After lamination is effected, side edges of the bulge are
joined with rear edges of the portions extending from the ankles to
the toe portion, and the side edges of the portion extending from
the ankles to the toe portion are joined together.
[0123] Of course, the base material and covering material are not
particularly limited in configuration and size as long as they are
larger in configuration and size than the exothermic composition
laminated on the base material. Specifically, however, it is
desirable that the base material and covering material are similar
or substantially similar in configuration to the fluid exothermic
composition placed in position and are formed larger than the
exothermic composition in such a way that they have an extension of
the order of few mm to 20 mm extending beyond the circumference of
the exothermic composition in all directions.
[0124] Where masses of the fluid exothermic composition are
laminated on the base material at plural sites, the base material
and the covering material may be bonded together by means of the
fluid exothermic composition. Of course, in order to assure
improved quality and improved reliability with respect to the foot
warming exothermic device, it is desirable that the base material
and the covering material are sealingly joined by heat bonding,
adhesion, or hot fusion bonding around the fluid exothermic
composition.
[0125] The method of forming the base material and covering
material to the predetermined configuration is not particularly
limited, but such forming may be performed when the base material,
covering material, and fluid exothermic composition are laminated
together, or may be carried out thereafter by, for example,
punching or fusing.
[0126] In any such method, from the standpoint of reducing the
number of operating stages and the time of operation thereby to
achieve cost reduction, it is presumed that circumferential edges
of the base material and covering material are joined together by
heat setting or heat sealing, and therefore it is desirable that
punching or fusing be carried out by heat setting rollers or heat
sealing rollers concurrently with the process of bonding.
[0127] With the foot warming exothermic device of the invention in
which a bulge is provided in continuation to the device, the
exothermic composition is placed in a thin sheet fashion between
the base material and the covering material, both of which have
flexing characteristics, and therefore the device is formed thin as
a whole. This enables the bulge to be readily deformed in
corresponding relation to the recess of the plantar arch, so that
the bulge can well conform to the recess of the plantar arch to
efficiently warm the entire sole of the foot.
[0128] As described above, in the first method of the invention,
the fluid exothermic composition is laminated by printing or
coating on the surface of the base material, and this permits the
fluid exothermic composition to be laminated in a thin sheet
fashion and uniformly. However, the fluid exothermic composition
may also be formed partially thick to provide a finger-pressure
treatment-like effect in addition to the heating effect.
[0129] That is, it is possible to laminate at least one time on
part of the surface of the fluid exothermic composition another
layer of the fluid exothermic composition to form a partially thick
portion, or to place at least a metal powder selected from among
the metal powder, a water absorber, and a carbon component, by
transfer or spraying on part of the surface of the fluid exothermic
composition laminated on the base material thereby to render the
exothermic composition thick in part.
[0130] In this way, by making the fluid exothermic composition
thick in part it is possible to control the distribution of heat
generation, or by making the fluid exothermic composition thick at
a site such as at the tip of the toe which is sensitive to cold, it
is possible to enhance the effect of warming. Further, it is
possible to arrange that at least a metal powder selected from
among the metal powder, a water absorber, and a carbon component is
transferred or sprayed on the exothermic composition to form
barrier layers, thereby to cause the metal powder to absorb
moisture forming the barrier layers so that an initial temperature
rise of the foot warming device can be accelerated when the device
is taken out from a gas-tight outer pouch.
[0131] In this case, the fluid exothermic composition placed on the
surface of the base material may be locally formed thick at a
position corresponding to the recess of the foot and/or the
vicinity thereof to provide a favorable thermotherapy-like and/or
toe pressure treatment-like effect.
[0132] Of course, the number of sites at which the fluid exothermic
composition is formed thick is not limited to one, and the
composition may be placed thick at two or more sites.
[0133] Further, in the first method of the invention, it is
desirable that at any suitable time point prior to a finished foot
warming exothermic device is enclosed into an air-tight outer
pouch, an adhesive layer has been formed on an exposed surface of
one of the base material and the covering material, the other
material being partially gas permeable, because such arrangement
permits the foot warming exothermic device to be adhesively
attached securely to the foot surface or a sock or a shoe.
[0134] The adhesive layer is not particularly limited as long as it
is adhesively attachable to foot surface, sock, and shoe.
Specifically, for example, a wet pack medication layer or a layer
formed of adhesives to be described hereinafter may be mentioned as
such.
[0135] Adhesives usable in forming such an adhesive layer include,
for example, solvent-type adhesives, emulsion type adhesives, and
hot-melt type adhesives. Specific examples of these adhesives are
rubber-based adhesives, vinyl acetate-based adhesives,
ethylene-vinyl acetate adhesives, polyvinylalcohol-based adhesives,
polyvinylacetal-based adhesives, vinyl chloride-based adhesives,
acrylic adhesives, polyamide-based adhesives, polyethylenic
adhesives, cellulose-based adhesives, polysulfide adhesives, and
hot-melt type polymeric containing adhesives.
[0136] Specific examples of hot-melt type adhesives include A-B-A
type block copolymer, saturated polyester high polymer, polyamide
high polymer, acrylic high polymer, urethane high polymer,
polyolefin high polymer, and polyolefin copolymer, modifications
these materials, and a mixture of two or more kinds of these
materials.
[0137] The modifications are those hot-melt high polymers part of
which is replaced by other component in order to improve their
properties such as tackiness or stability.
[0138] In A-B-A type block copolymer, A block is a monovinyl
replaced aromatic compound A such as styrene or methyl styrene
which is an inelastic polymer block, and B block is an elastic
polymer block of conjugate diene such as butadiene or isoprene.
[0139] Specific examples include styrene-butadiene-styrene block
copolymer, and styrene-isoprene-styrene block copolymer, and a
mixture thereof.
[0140] Commercially available ABA type block copolymers include
Califlex TR-1101, Califlex TR-1107, Califlex TR 1111 (manufactured
by Shell Chemicals, and Solprene 418 manufactured by Phillip
Petroleum.
[0141] Of the foregoing adhesives, rubber-based adhesives, acrylic
adhesives, and adhesives containing hot-melt type high polymer
material are preferred, since an adhesive layer comprised of such
adhesive can adhere well to a surface such as, foot surface, sock
or shoe. More particularly, an adhesive layer containing a hot-melt
type high polymer material is preferred because it exhibits good
initial tack, and also exhibits very high adhesion during heat
application.
[0142] The thickness of the adhesive layer is not particularly
limited, but a thickness range of from 5 to 1000 .mu.m is
preferred, especially from 10 to 500 .mu.m, more preferably from 15
to 250 .mu.m. If the thickness of the adhesive layer is less than 5
.mu.m, it is difficult to obtain the required adhesion strength. A
layer thickness of more than 1000 .mu.m is not only meaningless but
uneconomical.
[0143] In the first method of the invention, where an adhesive
layer is formed on an exposed surface of the foot warming
exothermic device, it is desirable that the exposed surface of the
base material or covering material be roughened or be comprised of
paper, card board, card board core material, woven fabric, nonwoven
fabric of rayon or the like, or rough-surfaced thin sheet such as
foamed thin sheet in order to provide increased strength of bond of
the adhesive layer with the base material or the covering
material.
[0144] In the first method of the invention, where an adhesive
layer is formed on one surface of the exothermic device as above
said, the adhesive layer contains or carries at least one of
compress medication, far infrared radiator, magnetic material, and
skin absorbable medication as desired. Thus, in addition to the
warming effect of heat generation of the exothermic device for
improvement of general physical functions including blood
circulation, various other effects can be obtained including
compress medication effect, far infrared radiation effect, magnetic
treatment effect, and endermic effect, and all these effects can
operate synergistically to enhance general or local therapeutic
effect.
[0145] The skin absorbable medication is not limited as long as it
is skin absorbable. Specific examples thereof include a skin
stimulant, anodyne/antiphlogistic, central nerve active agents
(soporific/sedative, psychoneurotic agent, etc.), diuretic,
hypotensive, coronary vasodilator, antitussive/expectorant,
antihistaminic, anti-arrhythmic, cardiac, adrenocortical hormone
drug, local anesthetic, and an organic acid such as acetic acid
which is a medicament for athlete's foot, of course, one type of
these medicines, or a blend of two or more types thereof, may be
used as required.
[0146] The amount of skin absorbable medication used is not limited
as long as a medical effect is expected but, from the point of view
of pharmacological effect and economy, and from the point of view
of adhesion, the amount of medication may be suitably determined
within the range of from 0.01 to 25% by weight, more particularly
from 0.5 to 15% by weight, relative to 100% by weight of the
adhesive.
[0147] The configuration of the far infrared radiator is not
limited to a particular configuration. Specifically, for example,
the radiator may be a formed mass which can serve as a toe press
agent to provide a toe pressure effect. However, in order to
enhance the flexibility of the foot warming exothermic device and
its ability to conform to the foot surface, it is preferable that
the far infrared radiator be of powder form.
[0148] As described above, the first method of the invention uses
an exothermic composition viscosified in a fluid form which has
exceptionally high fluidity in contrast to the prior art exothermic
composition which has a wetting characteristic and is of powder
form. This permits the exothermic composition to be laminated by
printing or coating on base material as supplied at high velocity,
the lamination being performed in succession and accurately,
uniformly and very thin within a predetermined space.
[0149] Therefore, the fluid exothermic composition can be laminated
very thin on the base material. This makes it possible to provide
an ultra-thin foot warming exothermic device such that its
thickness poses no problem when the device is placed in a shoe.
Since the foot warming exothermic device can be made to such an
extra thin size, the invention provides exceptionally good
advantages that the device has good flexibility and presents no
unharmonious feel when in use, and that the device can well conform
to any complex concave and convex configuration, such as curves and
bends, at the desired site of the foot.
[0150] The fluid exothermic composition can be accurately laminated
within the predetermined space on the base material, and this
enables the fluid exothermic composition to be accurately
distributed in a space corresponding to the desired site of the
foot without waste. Since warming heat can be efficiently applied
in this way to the desired site of the foot which requires warming,
good warming effect can be obtained and general physical functions
including blood circulation can be effectively enhanced. In
addition, the fluid exothermic composition does not involve any
such dissipation of powder of the exothermic composition as has
hitherto been experienced, and enables such plant management as
will meet the GMP standards in the manufacture of medical tools and
medicament in the future.
[0151] Further, as already stated, the fluid exothermic composition
can be uniformly laminated on the base material, and this prevents
the development of any abnormal high temperature point or abnormal
high temperature site due to unbalanced distribution of the
exothermic composition and generation of a low temperature burn as
well, thereby enhancing safety in use.
[0152] The first method of the invention uses a fluid exothermic
composition which can easily be transferred by printing, coating or
the like and enables the manufacture of an ultra-thin foot warming
exothermic device at high rate. Moreover, in contrast to the case
with prior art exothermic compositions, where the exothermic
composition contains any excess of water, the excess water forms
water barriers to diminish air supply and substantially stop the
exothermic reaction, with the result that various harmful problems
due to such occurrences as heat generation loss in the process of
manufacture, and quality degradation and coagulation of the
exothermic composition can be effectively prevented.
[0153] In the first method of the invention, the fluid exothermic
composition is laminated by printing or coating on the surface of
the base material in at least one predetermined region and in such
a configurational pattern as to cover the desired site of the foot,
and thereafter the thin sheet covering material is placed thereon
so as to cover the exothermic composition. In this case, for
example, by guiding the covering material by rollers onto the base
material and the fluid exothermic composition supplied at high
rate, the covering material can be placed on the base material and
the fluid exothermic composition without stopping the run of those
materials. In the first method of the invention, as is the case
with the prior art, after the covering material is placed in
position, the exothermic device is formed to the predetermined
configuration, and the so formed exothermic device is enclosed in a
gas-tight pouch, but the formation of the exothermic device and
enclosure of the same into the gas-tight pouch can be Carried out
in unison with the placement of the covering material.
[0154] Therefore, according to the first method of the invention,
it is possible to manufacture and package the foot warming
exothermic device by actuating, in unison with the feeding of the
base material, a fluid exothermic composition laminating unit for
laminating the exothermic composition, an exothermic device forming
unit for forming the foot warming exothermic device, and a
packaging unit for enclosing the foot warming exothermic device
into a gas-tight pouch, for example, while feeding the base
material continuously at a high speed on the order of 160 m or more
per minute, several times faster than the prior art. This enables
manufacture of the foot warming exothermic device on a volume
production basis and at low cost.
[0155] Further, operating stages, including placing the fluid
exothermic composition and covering material on the base material
to form the foot warming exothermic device, forming the foot
warming exothermic device into shape, and packaging the same, can
be carried out on an integrated basis, for example, within a short
period of time on the order of 0.1 to less than 1 second.
[0156] Therefore, the manufacturing process involves no possibility
of creating any conditions which may permit heat generation of the
exothermic composition, and thus heat generation of the exothermic
composition in the manufacturing process can be completely
prevented.
[0157] Accordingly, it is possible to completely eliminate
possibilities of such occurrences as exothermic loss, quality
degradation and coagulation of the exothermic composition which may
otherwise be caused due to heat generation in the manufacturing
process. Thus, various harmful effects such as decreased yield,
handling difficulty, maintenance trouble with respect to the
manufacturing equipment, limitations imposed on operating hours of
the manufacturing equipment and/or on working hours of operators,
and difficulty involved in the treatment of coagulated matter.
Hence, high quality and highly dependable exothermic devices can be
produced at lower cost.
[0158] Moreover, in such high speed manufacturing operation, the
base material feed unit, paste-like exothermic composition
laminating unit, covering material laminating unit, forming units,
such as punching unit for foot warming exothermic device. and
packaging unit for enclosing the foot warming exothermic device
into a gas-tight pouch can be continuously operated for
manufacturing operation. Therefore, in contrast to the prior method
of manufacturing a foot warming exothermic device in which all such
machines must be intermittently operated in placing a fluid
exothermic composition on a base material, it is only required that
adjustment be made to synchronize these units in their operating
velocity. Any timing adjustment is no longer necessary with respect
to operations of the different units. Only very simple control
adjustment is required. Thus, means for controlling operation
timing with respect to individual units, and the construction of
each unit is simplified.
[0159] In the first method of the invention, where the base
material and covering material have extensibility and/or stretch
and shrink characteristics, the exothermic device can more easily
conform to complex concave and convex configuration of the foot at
the desired site. The adaptability of the device to variations of
the concave and convex configuration due to movement of the foot
can be enhanced. Separation or floating of the foot warming
exothermic device from the site of application is positively
prevented. Thus, any decrease due to such separation or floating in
the warming effect of the device and in the promoting effect of
general physical function including blood circulation can be
prevented.
[0160] In the first method of the invention, where the base
material and/or covering material is water absorbable, the excess
water in the fluid exothermic composition is caused to be absorbed
by the base material and/or covering material prior to use whereby
the proportion of water in the exothermic composition can be
adjusted to a proportion suitable for heat generation. Therefore,
by breaking the gas-tight pouch before use it is possible to cause
heat generation to start at once whereby necessary exothermic
temperature can be promptly obtained. Further, water evaporated
from the exothermic composition as exothermic reaction progresses
can be replenished by moisture release from the base material or
the covering material, whereby the required exothermic temperature
can be retained for a long period of time.
[0161] In the first method of the invention, where the base
material and/or covering material are/is water absorbable, as the
material absorbs excess water in the fluid exothermic composition,
the exothermic composition is drawn toward the base material and/or
covering material, so that part of the fluid exothermic composition
bites into the base material and/or covering material to produce an
anchoring effect through which the fluid exothermic composition can
be fixed to the base material and/or covering material.
[0162] Therefore, in contrast to the prior art method in which the
exothermic composition is fixed within the wrapper by utilizing the
reduced pressure due to an exothermic reaction, the fluid
exothermic composition can be positively immobilized. This, coupled
with the fact that the foot warming exothermic device is formed
ultra-thin, positively prevents movement or displacement of the
fluid exothermic composition within the wrap. As a result, for
example, it is no longer necessary to shake the foot warming
exothermic device by hand when using it to eliminate uneven
distribution of the exothermic composition. Thus, the method of use
is simplified, and the development of any abnormal high temperature
spot or portion resulting from maldistribution of the fluid
exothermic composition can be surely prevented. Thus, occurrence of
a low temperature burn can be prevented and safety in use can be
more enhanced.
[0163] In the first method of the invention, for example, where the
fluid exothermic composition is formed partially thick because of a
separate layer of fluid exothermic composition laminated thereon,
or where at least metal powder, selected from metal powder, water
absorber, and carbon component, is laminated on part of the surface
of the fluid exothermic composition, so that the exothermic
composition is made partially thick, it is possible to increase the
quantity of heat generation at the thicker portion, develop a
therapeutic toe pressure, and/or prompt a rise of initial
temperature.
[0164] In such a case, therefore, the thickness of the layer is
locally thick, particularly at a particular recess portion of the
foot and in the vicinity thereof, to provide a thermotherapeutic
effect, and enhance warming effect at a site sensitive to cold,
such as the toe portion. Furthermore, through control of exothermic
temperatures, it is possible to prevent occurrence of a low
temperature burn, and enhance safety in use.
[0165] In the first method of the invention, where an adhesive
layer is formed on the exposed surface of one of the base material
and the covering material and at least part of the other is
gas-permeable, the adhesive layer may be applied directly to the
skin of the foot, or to the sock or the sole of a shoe. Thus, the
foot warming exothermic device can be readily fixed to the foot at
the desired site.
[0166] In this case, where at least one of a far infrared radiator,
magnetic material, and skin absorbable medication is contained in
or carried by the adhesive layer, heating effect of the far
infrared radiator, therapeutic effect of the far infrared radiator,
therapeutic effect of the magnetic material, and therapeutic effect
of the medication can be obtained. These effects, coupled with
general physical function promotion effect, such as blood
circulation enhancement, synergistically operate to provide even
better results.
[0167] In order to achieve the aforementioned object, a second
method of manufacturing a foot warming exothermic device of the
invention (hereinafter referred to as second method of the
invention) comprises: placing a fluid exothermic composition on a
thin sheet base material, then placing on top thereof a thin sheet
covering material, bonding said base material and said covering
material together utilizing the viscous characteristic of said
fluid exothermic composition, then punching the resulting laminate
to such a shape as to cover a desired foot site, one of said base
material and said covering material, or part of either one being
gas permeable.
[0168] The second method of the invention will now be described. In
the second method of the invention, a fluid exothermic composition
is first placed on a thin sheet base material, and then a thin
sheet covering material is placed thereon, the base material and
the covering material being bonded together by virtue of the
viscosity of the fluid exothermic composition, whereby a laminate
is obtained.
[0169] Fluid exothermic compositions usable in this second method
of the invention are similar to those in the first method of the
invention. Therefore, detailed description of those compositions is
not repeated here for the sake of brevity.
[0170] In the second method of the invention, as is the case with
the first method of the invention, until excess moisture present in
the fluid exothermic composition is absorbed by a water absorptive
thin sheet, any oxidation reaction, that is, exothermic reaction,
of the exothermic composition is inhibited, even when the
exothermic composition comes in contact with air. Therefore,
various harmful effects of any thermal loss due to a heat reaction
in the stage of manufacture, and quality degradation and
coagulation of the exothermic composition can be positively
prevented. The fluid exothermic composition can be laminated to a
uniform thickness. This, coupled with the bond of the exothermic
composition with the wrapper, prevents movement and displacement of
the exothermic composition. Any excessive thermal reaction of the
exothermic composition can be also avoided.
[0171] In the, second method of the invention, the method of
laminating the fluid exothermic composition on the base material is
not particularly limited. Specifically, however, coating by a
coater such as head coater, roller, applicator or the like is
exemplified as such. In the second method of the invention, it is
essential that at least one of the base material and the covering
material must be wholly or partly water absorptive. In other
respects, the base material and covering material are not
particularly limited as long as they are of thin sheet form.
Specifically, for example, materials enumerated in the description
of the first method of the invention may be mentioned as such. For
the sake of brevity, however, detailed description thereof is
omitted.
[0172] In the second method of the invention, the laminate obtained
in the manner as described above is punched to a shape covering a
desired site of the foot to give a foot warming exothermic device
in which at least one or part of the base material and covering
material is gas permeable.
[0173] In the second method of the invention, the laminate obtained
in manner as described above is punched to a shape covering a
desired site of the foot to give a foot warming exothermic device
in which at least one or part of the base material and covering
material is gas permeable.
[0174] The stage of punching the laminate to a predetermined shape
may be carried out with the laminate kept at a rest. In that case,
plural laminates arranged in the direction of laminate feed and in
a transverse direction rectangular to the direction of laminate
feed are punched simultaneously whereby a large number of foot
warming exothermic devices can be formed at one time. The use of
this method can result in a cost reduction.
[0175] This method, as already stated, is such that, for example, a
fluid exothermic composition is laminated on a thin sheet base
material being fed, and then a thin sheet form covering material is
guided by rolls onto the laminate. Where the covering material is
placed over the fluid exothermic composition to obtain a laminated
exothermic sheet, punching operation is carried out at the stage of
punching.
[0176] In this case, laminates are arranged in a transverse
direction rectangular to the direction of laminate feed, or
arranged in staggered relation to both the direction of feed and
the transverse direction are simultaneously punched on a continuous
basis, whereby a larger number of foot warming exothermic devices
can be completed, which means a larger cost reduction.
[0177] The laminate is punched out to such a configuration as to
cover a desired site of the foot.
[0178] In the second method of the invention, each laminate
obtained is punched to such a configuration as to cover a desired
site of the foot. The configuration of the punched-out foot warming
exothermic device is not particularly limited, but may be
determined as desired. Specific examples of such configuration are
same as those noted with respect the first method. For the sake of
brevity, detailed explanation of such configurations is
omitted.
[0179] In the second method of the invention, the base material and
the covering material are adhesively joined together by virtue of
the viscosity of the fluid exothermic composition, and thereafter
excess water is absorbed into the base material and covering
material. The resulting foot warming exothermic device is enclosed
in a non-gas-permeable outer wrapper, in which state the device may
be delivered as a commercial article to the distribution
system.
[0180] However, it is desirable that the punched-out foot warming
exothermic device be interposed between two thin sheets and,
simultaneously with or after this interposition, the two thin
sheets are punched out to a larger size than the foot warming
exothermic device, and that before or simultaneously with or after
this punching operation the two thin sheets are sealingly joined
along the peripheral edge of the foot warming exothermic
device.
[0181] In this case, at least one or part of the two thin sheets is
gas permeable. In this way, a more reliable foot warming exothermic
device is obtained.
[0182] Through the above described process is obtained a foot
warming exothermic device of a desired configuration. The quantity
of air supplied to the exothermic composition in the device is
controlled through the gas permeability of the two thin sheets.
Therefore, the control of gas permeability with respect to the
exothermic composition is made on the basis of moisture
permeability in the same manner as in the case of gas permeability
control with respect to the base material and/or covering material
in the first method of the invention. Referring to moisture
permeability, it is noted that the moisture permeability of the
laminated thin sheet including one of the two thin sheets and the
base material or covering material is similar to the description
given for the first method of the invention. For the sake of
brevity, therefore, detailed description is omitted.
[0183] The two thin sheets may comprise a non-gas-permeable one and
a gas-permeable one. They may have tackiness, heat adhesive
characteristics, or hot fusibility.
[0184] A sheet having tackiness may comprise a base sheet and a gas
permeable adhesive layer formed over the entire surface thereof,
the adhesive layer being formed of a hot melt type adhesive, or may
be one having a partially gas-permeable or gas impermeable adhesive
layer formed all over the surface. Whether or not the base sheet
itself has heat adhesivity or hot fusibility is not important.
[0185] In the second method of the invention, a foot warming
exothermic device is interposed between the two thin sheets and,
simultaneously with or after this interposition, the two sheets are
punched out to a larger size than the foot warming exothermic
device, and before or simultaneously with or after this punching
operation the two sheets are sealingly joined along the peripheral
edge of the foot warming exothermic device.
[0186] The punching operation may be made with a continuous foot
warming exothermic device interposed between two sheets as held in
a static condition. In this case, punching is made with plural
continuous exothermic devices arranged in the direction of feed and
those arranged in a transverse direction rectangular to the
direction of feed, by punching them simultaneously. This permits a
large number of exothermic devices to be punched at one time, which
leads to cost reduction.
[0187] In the second method of the invention, after the continuous
exothermic device has been made, two lengths of thin sheets are
sealingly joined along the peripheral edge of the foot warming
exothermic device prior to the punching of the continuous
exothermic device or simultaneously with the punching of the
continuous exothermic device, or after the punching of the
continuous exothermic device.
[0188] In connection with the operation of punching into a larger
size than the foot warming exothermic device, the larger size is
not particularly limited as long as the size is larger than the
size of the foot warming exothermic device. However, it is
desirable that the punched out configuration is similar to the
configuration of the foot warming exothermic device and is larger
in size than the contour of the device, extending outward of the
peripheral edge of the device on the order of a few mm to 20
mm.
[0189] In the second method of the invention, the extended portion
is sealingly secured. That is, the two thin sheets are sealingly
joined by adhesion, heat bonding or hot fusion around the
peripheral edge of the foot warming exothermic device.
[0190] In the second method of the invention, an adhesive layer may
be formed over the whole or part of the exposed surface of one of
the laminate components and at least part of the other component is
gas permeable.
[0191] In this case, where at least one compress medication, far
infrared radiator, magnetic material, and skin absorbable
medication is contained in or carried by the adhesive layer,
effects similar to those in the first method of the invention can
be obtained. Repetition of details about this is avoided for the
sake of brevity.
[0192] In the second method of the invention, the fluid exothermic
composition is laminated on the thin sheet base material, then the
thin sheet covering material is placed on the laminate, whereby the
base material and the covering material are joined together by
means of viscosity of the fluid exothermic composition. Then, the
resulting laminate is punched into such a shape as to cover a
desired site of the foot. At least one or part of the base material
or covering material is gas permeable.
[0193] Therefore, manufacture of an ultra-thin foot warming
exothermic device is possible, and the use of the fluid exothermic
composition enables formation of barrier layers by excess water
which inhibits an exothermic reaction. Thus, the method prevents
various problems which may otherwise arise from heat generation
loss, quality degradation of the fluid exothermic composition, and
coagulation of the composition in the stage of manufacture.
Furthermore, the fluid exothermic composition is uniformly
distributed within the pouch and immobilized therein, whereby
movement and displacement of the fluid exothermic composition can
be prevented. Thus, the possibility of excessive exothermic
reaction of the exothermic composition is minimized so that the
problem of low temperature burn is avoided and safety in use is
enhanced.
[0194] The foot warming exothermic device of the invention is
characterized in that it is manufactured according to the first
method or the second method of the invention in order to achieve
the foregoing objects. The configuration of the foot warming
exothermic device is not limited. Specifically, however, the device
may be so configured as to cover a desired site of the foot and,
more particularly, to cover, for example, the sole of the foot, or
part or the whole of the instep of the foot.
[0195] The foot warming exothermic device of the invention is
manufactured by the first method or the second method of the
invention, and is a high quality device of the kind and is highly
reliable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0196] FIG. 1 is a plan view of a first embodiment of the present
invention;
[0197] FIG. 2 is a schematic sectional view of the first embodiment
of the invention;
[0198] FIG. 3 is a plan view of a second embodiment of the
invention;
[0199] FIG. 4 is a plan view of a third embodiment of the
invention;
[0200] FIG. 5 is a plan view of a fourth embodiment of the
invention;
[0201] FIG. 6 is a perspective view of the fourth embodiment of the
invention;
[0202] FIG. 7 is a perspective view of a fifth embodiment of the
invention;
[0203] FIG. 8 is a development of a sixth embodiment of the
invention;
[0204] FIG. 9 is a schematic view in section of a seventh
embodiment of the invention;
[0205] FIG. 10 is a plan view of the seventh embodiment of the
invention;
[0206] FIG. 11 is a plan view of an eighth embodiment of the
invention;
[0207] FIG. 12 is a plan view of a ninth embodiment of the
invention;
[0208] FIG. 13 is a plan view of a tenth embodiment of the
invention; and
[0209] FIG. 14 is a plan view of the tenth embodiment when in
use.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0210] Embodiments of the invention will now be described in detail
with reference to the drawings. It is understood, however, that the
invention is not limited to these embodiments.
[0211] A first embodiment of the invention is one example of a
method of manufacturing a foot warming exothermic device for
warming the back of the toes of the foot according to the first
method of the invention, and of a foot warming exothermic device
manufactured by the method. FIG. 1 shows a plan view of the foot
warming exothermic device.
[0212] This foot warming exothermic device was manufactured
according to the following procedure. On a base material 1 having
water absorbing power, as it was paid out, was screen printed as a
fluid exothermic composition 2 in a desired pattern. Then, an
adhesive was coated on an exposed surface surrounding the fluid
exothermic composition 2, and a covering material 3, as guided by a
roller, was placed on the composition from above. The base material
1 and the covering material 3 were bonded together, with the fluid
exothermic composition 2 sandwiched between them. Then, an adhesive
layer 5 having a thickness of 50 .mu.m was formed on an exposed
surface of the base material 1. A continuous exothermic sheet thus
obtained was extended about 7 mm by a roll press from the fluid
exothermic composition 2 and was punched into a trapezoidal shape
intended to cover the back of the toes.
[0213] As a schematic sectional view of FIG. 2 shows, the base
material 1 is a laminate consisting of a water absorbable rayon
nonwoven fabric 1a of about 80 g/m.sup.2 and a gas impermeable and
water impermeable polyethylene sheet 1b of about 50 .mu.mm wide,
with a fluid exothermic composition 2 printed on the nonwoven rayon
fabric 1a of the base material 1 for direct contact therewith.
[0214] The covering material 3 is a laminate consisting of a water
permeable rayon nonwoven fabric 3a of about 80 g/m.sup.2 and a gas
permeable polyethylene sheet 3b having a width of about 50 .mu.,
the laminate having a moisture permeability of 1000 g/m.sup.2. The
covering material 3 is so laminated as to allow the fluid
exothermic composition 2 to come in direct contact with the rayon
nonwoven fabric 3 of the covering material 3.
[0215] For the adhesive layer 5 an acrylic adhesive is used. In
order to enhance the adhesion of the adhesive layer 5 to the base
material 1, the exposed surface of the polyethylene sheet 1b of the
base material 1 has been previously roughened by corona treatment
to a wetting index of the order of 40 dyne or more.
[0216] The fluid exothermic composition 2 was prepared by blending
100 parts by weight of iron powder, a heat generating material (DKP
manufactured by Dowa Teppun K, K,), 0.5 part by weight of water
absorptive polymer (5000 MPS manufactured by Sanyo Kasei K. K.),
1.4 parts by weight of thickener (Celogen EP manufactured by Dauchi
Kogyo Seiyaku K. K.), 8.6 parts by weight of activated carbon 5
(SA-SUPER manufactured by Norit), 4.3 parts by weight of sodium
chloride as a metal chloride, and 0.3 part by weight of sodium
polyphosphate as a pH adjustor, and adding excess water to the
blend to provide a viscosity of 500,000 cps or so at a temperature
of 20.degree. C.
[0217] The word "viscosity" herein means a viscosity value measured
by using a viscometer, type BH manufactured by Tokimec Inc., with a
#7 rotor at a rotational speed of 2 rpm and a beaker having an
inner diameter of 85 .o slashed.mm, at a temperature of 20.degree.
C.
[0218] Therefore, the fluid exothermic composition contains excess
water which functions as a barrier layer to prevent contact between
the iron powder and air. As a result, it has been found that no or
little, if any, exothermic reaction does occur.
[0219] When the fluid exothermic composition 2 is screen printed on
the base material 1 to a thickness of 20 .mu.m, the excess water in
the exothermic composition begins to be absorbed by the water
absorptive nonwoven rayon fabric 1a and, after the covering
material 3 is placed, excess water is absorbed by the rayon
nonwoven fabric 3a of the covering material 3 until the proportion
of water in the exothermic composition 2 reaches the optimum
condition for generation of the preset exothermic temperature.
[0220] However, whereas some time is required before the excess
water is absorbed by the base material 1 and covering material 3
until the predetermined water content is reached, the time required
after the fluid exothermic composition 2 is printed on the base
material 1 and until the resulting foot warming exothermic device
is enclosed in the gas impermeable pouch is zero point odds second
at most, there being no possibility that the proportion of water in
the fluid exothermic composition 2 reaches the optimum proportion
for generation heat before the device is enclosed in the gas
impermeable pouch.
[0221] Thus, there is no possibility of the fluid exothermic
composition 2 generating heat before the foot warming exothermic
device is enclosed in the gas impermeable pouch, nor is there any
possibility that exothermic reaction products coagulate before such
time, resulting various harms including, for example, decreased
yield, handling difficulty, complex maintenance work with the
manufacturing equipment, limitations imposed upon operating time of
the manufacturing equipment or operator working hours, and
difficult jobs involved in coagulated matter handling.
[0222] The excess water in the fluid exothermic composition 2 is
absorbed by the water absorptive rayon nonwoven fabric 1a of the
base material 1 and the water absorptive rayon nonwoven fabric 3a
of the covering material 3 so that the proportion of the water will
reach a suitable level for realizing a suitable proportion of water
to obtain the predetermined exothermic temperature after the foot
warming exothermic device is enclosed in the gas impermeable pouch
and before it is delivered to the user through a distribution
channel. Therefore, the exothermic composition 2 is not liable to
quality deterioration before the gas impermeable pouch is broken to
allow the content to be exposed to air, so that the exothermic
composition 2 can be maintained in high quality. Moreover, an
exothermic reaction starts immediately when the pouch is broken for
removing the foot warming exothermic device, and the predetermined
exothermic temperature is quickly reached.
[0223] Furthermore, the fluid exothermic composition 2 has high
fluidity and can be laminated on the base material 1 by printing or
coating. Therefore, in contrast to the case of the prior art in
which an exothermic composition in powder form is simply placed on
the base material 1, the fluid exothermic composition can be
accurately laminated at high speed within the predetermined range
and to a uniform thickness.
[0224] The foot warming exothermic device, enclosed in a gas
impermeable pouch, was allowed to stand for 10 days. Thereafter,
the pouch was broken to remove the foot warming exothermic device
and then the device was applied by using an adhesive layer 5
directly to the back of a portion of the foot extending from the
toes to the balls of the base of the toes. Good exothermic effect
was obtained over more than 6 hours.
[0225] During this application of the foot warming exothermic
device, it was found that by virtue of its ultra-thin formation the
exothermic device was flexible as a whole so that it felt soft to
the foot, readily deformed along a curved portion of the foot,
conformed to the concave and convex configuration of the back of
the toes, followed the movement of the sole of the foot very well
through its deformation, and exhibited good contact capability
relative to the site of application. No separation of the
exothermic device from the site of application was observed and
good warming effect was obtained. It was found that the device
warmed the toes of the foot effectively from the back.
[0226] In such application, the adhesive layer 5 of the foot
warming exothermic device can be applied directly to the back of
the foot. Therefore, it is possible to effectively warm from the
sole side over a range extending from the toe to the balls at the
base of the toes.
[0227] Further, during such application, the exothermic composition
2 is not liable to movement, and distribution of the exothermic
temperature of the foot warming exothermic device is uniform, there
being no possibility of low temperature burn, which means higher
safety in use.
[0228] The configuration of the foot warming exothermic device of
the invention is not limited to that in the foregoing embodiment.
For example, in the foot warming exothermic device representing the
second embodiment of the invention shown in plan in FIG. 3, the
fluid exothermic composition 2 (2a, 2b) is printed on a wrapper
consisting of an inner sole cover-like base material 1 and a
covering material 3 in such a way that a semi-elliptic portion
extending from the toes of the foot to the toe root and a plantar
arch portion are separately printed, and portions other than those
for the fluid exothermic composition are adhesively joined.
[0229] In this case, though not shown, the device may be
alternatively a foot warming exothermic device for toe use such
that on the semi-elliptic base material is printed a fluid
exothermic composition smaller than the base material but similar
thereto, and a covering material of the same shape as the base
material is placed on them from above and sealingly joined with
them. Another alternative form may be a foot warming exothermic
device for the plantar arch such that on a base material of a
crescent shape is printed a fluid exothermic composition smaller
than the base material but similar thereto in shape, and a covering
material of the same shape as the base material is placed on them
from above and sealingly joined with them.
[0230] Instead of the above form, though not shown, in a wrapper
consisting of an inner sole cover-like base material 1 and a
covering material 3, the fluid exothermic composition may be
printed over a generally whole surface of the base material than
the peripheral sealing edge portion so that the sole of the foot
can be warmed almost all over.
[0231] The foot warming exothermic device representing a third
embodiment of the invention shown in plan in FIG. 4 is such that in
a wrapper consisting of an inner sole cover-like base material 1
and a covering material 3 the fluid exothermic composition 2 is
printed in belt form over the entire surface of the sole portion
excepting a side portion of the sole adjacent the plantar arch
which contacts the ground. The portion other than the fluid
exothermic composition 2 may be sealingly closed by adhesion. The
foot warming exothermic device representing a fourth embodiment of
the invention is such that the fluid exothermic composition 2 is
printed on a front sole portion 2 (2a), a plantar arch and portion
extended therefrom 2 (2b), and a heel portion 2 (2c). Portions
other than the fluid exothermic composition may be sealingly closed
by adhesion.
[0232] According to the first method of the invention, the foot
warming exothermic device may be configured to cover any desired
site. For example, the foot warming exothermic device may be formed
into an inner cover type configuration as shown in FIG. 3 or 4, or
may be formed into such a configuration that a portion of the
peripheral edge portion of an inner sole cover pattern A, for
example, a portion corresponding to the plantar arch is extended as
shown in FIGS. 5 and 6 depicting the fourth embodiment.
[0233] Where the foot warming exothermic device is extended from a
portion corresponding to the plantar arch in this way, with the
fluid exothermic composition 2 disposed also in the extended
portion in continuation to the plantar arch, when the foot warming
exothermic device is placed in a shoe, or when it is applied to the
sole of the foot, the foot pattern A and the portion B extended in
continuation thereto can be deformed along a side of a portion of
the foot including the plantar arch and a portion continued
therefrom, so that the plantar arch and a portion extending
therefrom to a side of the foot can be covered with the exothermic
composition. Thus, a portion of the plantar arch at which a large
number of pores concentrate can be effectively warmed by supplying
warming heat to that portion from side and bottom, whereby good
thermo-therapeutic effect can be obtained.
[0234] In a fifth embodiment of the invention shown in perspective
in FIG. 7, the device includes, in addition to the above
arrangement, an instep front portion 7 covering the tip of the toe
and the upper side of the base of the toes, a bulged portion 8
continued from the rear edge of a portion corresponding to the heel
and extending to a position above the ankle portion, and adhesive
portions 9,10 provided in continuation to both sides of the end of
the bulged portion 8.
[0235] The fluid exothermic composition 2 (2a, 2b, 2c, 2d, 2e)
comprises a horseshoe-like portion (2a) corresponding to the ball
up to the toe, a portion (2b) corresponding to the plantar arch
including a foot pattern portion A and bulge B, a portion (2c)
corresponding to the heel, a portion (2d) corresponding to a rear
upper portion of the ankle, and a portion (2e) above the toes,
these portions being separately disposed.
[0236] This foot warming exothermic device is suitably applicable
to sandals and may be used just as in putting on a sandal, with the
toe inserted between the instep front portion 7 and the foot
pattern portion A, that is, the toe inserted between the
horseshoe-like portion (2a corresponding to the ball up to the toe
and the portion (2e) above the toes, with the adhesive portions 9
and 10 applied to the upper side of the ankle.
[0237] The exothermic composition (2a) disposed at the
horseshoe-like portion corresponding to the ball up to the toe and
the exothermic composition (2e) disposed at the portion above the
toes warm, from above and from below, a site of from the toe to the
ball at the toe root, and the exothermic composition (2b) disposed
at the portion corresponding to the plantar arch including foot
pattern portion A and bulge B well conforms to the concave and
convex configuration of the plantar arch to efficiently warm the
plantar arch. The exothermic composition (2c) disposed at the site
corresponding to the heel warms the heel from below and the
exothermic composition (2c) disposed at the portion corresponding
to the upper rear side of the ankle warms Achilles' tendon and its
vicinity.
[0238] The exothermic composition (2c) disposed at a site
corresponding to the upper rear side of the ankle contains a
compress medication to provide a therapeutic compress effect for
treatment of achillodynia.
[0239] In a sixth embodiment of the invention shown in FIG.
development view, a wrapper consisting of base material 1 and
covering material 3 divides a sock into symmetrical parts, right
and left, which parts are held in continuation centrally of the
sole of the sock.
[0240] That is, on a raw fabric for base material 1 comprised of a
water absorptive and gas permeable, stretchable nonwoven fabric (40
g/m.sup.2 thick)/porous film (10 .mu.m thick) polyester nonwoven
fabric (60 g/m.sup.2 thick, impregnated with 10 g/m.sup.2 of CMC)
is printed as a fluid exothermic composition 2 in divisions to a
predetermined pattern. On these is placed a raw fabric for covering
material 3 consisting of a water absorptive and gas permeable,
stretchable nonwoven fabric (40 g/m.sup.2 thick)/porous film (40
.mu.m)/polyester nonwoven fabric (60 g/m.sup.2 thick, impregnated
with 10 g/m.sup.2 of CMC). Peripheral edge portions of the base
material 1 and the covering material 3 are cut by fusion.
[0241] In this case, the peripheral edges of the base material 1
and the covering material 3 are sealingly joined, and the base
material 1 and the covering material 3 are bonded together with the
fluid exothermic composition 2. Thus, any outward leak of the fluid
exothermic composition or movement of the exothermic composition
between the base material 1 and the covering material 3 during use
of the device is prevented. Any abrasive contact at the portion
corresponding to the ankle may give a disagreeable feel and,
therefore, the fluid exothermic composition 2 is disposed at
portions other than the ankle portion.
[0242] Then, a foot warming exothermic device obtained by fusion
cutting is folded in the center of a sock, which may be used in
such a way as to enclose the edge 11 extending from the toe through
the instep to the ankle and the edge 12 extending from the heel to
the ankle, for example, in a boot.
[0243] With the foot warming exothermic device of this embodiment,
back side, instep side, and side portions extending from the upper
side of the ankle to the toe are totally warmed, except the ankle
joint portion. Since the foamed polyethylene sheet of the covering
material 3 contacts the skin of the foot, flexibility of the device
is enhanced to give a comfortable feel to the skin.
[0244] In the foot warming exothermic device representing a seventh
embodiment of the invention shown in fragmentary section in FIG. 9
and in plan in FIG. 10, a card board for insertion between the base
material 1 and the covering material 3 is omitted. The fluid
exothermic composition is screen printed on the base material 1,
and then the covering material 3 is placed on the base material and
fluid exothermic composition from above, at which time adhesion
bonding is effected to join the entire portions around the fluid
exothermic composition 2. Simultaneously, the joined portions are
punched out to the predetermined shape.
[0245] In this embodiment, the covering material 3 comprises an
outer layer consisting of a polypropylene nonwoven fabric (Type
2030, manufactured by Idemitsu; weight per unit area 30 g/m.sup.2)
3a, and a porous film (Espoire, manufactured by Mitsi Toatsu K. K.,
moisture permeability 4000 g/m hr), and an inner layer formed of
cardboard K liner (NS liner, manufactured by Nihon Shigyo, weight
per unit area 200 g/m.sup.2, water absorption 114 g/m.sup.2) 3c,
which components are laminated through the intermediary of an
adhesive made by melt blow (Type 5Q543, manufactured by NSC). A
quantity of this adhesive used is 5 g/m.sup.2 between nonwoven
fabric 3a and porous film 3b; and 30 g/m.sup.2 between porous film
3b and cardboard K liner 3c.
[0246] In this embodiment, as FIG. 10 shows, a printing pattern of
the fluid exothermic composition 2 is formed over the whole sole
portion, except the heel portion, the sole portion being divided by
lattice-like non-printed portions into plural regions. In these
lattice-like non-printed portions, outer edge portions are bonded
simultaneously when the base material 1 and the covering material 3
are bonded together. In this embodiment, therefore, movement of
exothermic composition 2 beyond respective region is more
positively prevented and the flexibility of the device as a whole
is very noticeably enhanced.
[0247] In this embodiment, the device as a whole has an inner sole
cover configuration. Therefore, no adhesive layer 5 is provided, in
which point the embodiment is different from Example 1.
[0248] With the exception of the above noted point in which this
embodiment is different from the Example 1, other aspects of the
construction of this embodiment are the same as those of Example 1,
including the composition of the thin exothermic composition and
the thickness thereof.
[0249] This foot warming exothermic device was enclosed in a gas
tight pouch and the same was allowed to stand for 30 days.
Thereafter, the gas tight pouch was broken to remove the foot
warming exothermic device. The device, placed in a shoe for use.
Good warming effect was obtained over a period of 7.5 hours.
[0250] The foot warming exothermic device representing an eighth
embodiment of the invention shown in plan in FIG. 11, the foot
warming exothermic device representing a ninth embodiment of the
invention shown in plan in FIG. 12, and the foot warming exothermic
device representing a tenth embodiment of the invention shown in
FIG. 13 include, in addition to a bulged portion B(B1) continued to
a plantar arch portion of a foot pattern portion A, a bulged
portion B(B2) covering the front end of the toe from the toe end
portion, and a bulged portion B(B3) covering the instep of the foot
from the toe in continuation to the bulged portion B(B2), and have
the fluid exothermic composition 2 disposed all over therein with
the exception of a portion between the toe and the bulged portion
B(B2) which is to be bent slightly when in use and a portion
connecting between two bulged portions B(B2, B3) of the toe.
[0251] In the foot warming exothermic device representing a ninth
embodiment of the invention shown in FIG. 12, and the foot warming
exothermic device representing a tenth embodiment of the invention
shown FIG. 13, bulged portion B (B2, B3) on the toe side which
corresponds to a site at which toe movement is particularly active
has the thin exothermic composition 2 disposed therein in divided
lots so that the movement of exothermic composition in that portion
is prevented in a more positive and refined manner.
[0252] With any of these foot warming exothermic devices, in use,
by simply folding the bulged portion B(B2, B3) from the toe onto
the instep it is possible to warm the toe portion from three
directions, namely, from the sole side, the toe side, and the
instep side.
[0253] In the case of the foot warming exothermic device
representing the ninth embodiment of the invention shown FIG. 12,
as well as the foot warming exothermic device representing the
tenth embodiment of the invention shown in FIG. 13, the fluid
exothermic composition 2 is printed part by part in plural regions
so that the exothermic composition and/or exothermic reaction
products can be more positively prevented.
[0254] In the case of the foot warming exothermic device
representing the tenth embodiment of the invention shown in FIG.
13, stop belts 13 extend from both ends of the front portion of the
foot, with an adhesive portion 14 laminated at the front end of the
stop belt 13.
[0255] In use, as FIG. 14 shows in plan, both stop belts 13 are
placed over the bulged portion B (B3) folded over the instep, and
the adhesive layer 14 is placed on the bulged portion B(B3) for
adhesion therewith, whereby the device is formed into a
slipper-like shape.
[0256] The foot warming exothermic devices of a complex
configuration of the foregoing embodiments use a fluid exothermic
composition in particular as necessary an exothermic composition,
and because of this fact it is possible to laminate the fluid
exothermic composition by printing or the like on the base material
to a desired pattern, which has been impossible in the prior
art.
[0257] Not shown, though, over the entire surface of a cardboard
core of 180 g/m.sup.2, as a base material, was printed a fluid
exothermic composition similar to the one used in Example 1 to the
thickness of 820 .mu.m, and on top of them was placed cardboard
core of 180 g/m.sup.2 of a similar type, as a covering material, by
passing the same through lap rolls so that the base material and
the covering material were joined together by virtue of the
viscosity of the fluid exothermic composition. Thus, a continuous
exothermic sheet was produced. Then, by using a roll press the
continuous exothermic sheet was continuously punched into an inner
sole cover-like shape. Then, the resulting foot warming exothermic
device was interposed between a laminated thin sheet formed of 40
.mu.m polyethylene film/12 .mu.m polyester thin sheet and a
laminated thin sheet (moisture permeability 850 g/m.sub.2) formed
of 40 .mu.m polyethylene porous thin sheet/30 g/m.sup.2
polypropylene nonwoven fabric. The laminate was punched to a size
of about 7 mm larger over its entire periphery than the foot
warming exothermic device and was heat sealed at the same time,
whereby a foot warming exothermic device was obtained.
[0258] Then, the foot warming exothermic device was enclosed in a
gas impermeable pouch and was allowed to stand one day. Then, the
gas impermeable pouch was broken for use. Good exothermic effect
was obtained.
[0259] In this case, the base material and the covering material
are inexpensive and the two films can be sealingly joined by heat
sealing. This enables continuous production of the foot warming
exothermic device.
[0260] Further, since the base material and the covering material
are bonded together by means of the viscosity of the fluid
exothermic composition, the exothermic sheet can be easily produced
at low cost.
[0261] Furthermore, since the exothermic device is packed in such a
condition that it is sandwiched between gas permeable cardboard
cores without adhesion, air is easily allowed to flow toward both
surface and back sides during the walk of the user, and accordingly
a contact area between the exothermic device and water is present
on both surface and back sides. Therefore, reaction efficiency is
enhanced even in the case of one side air permeation.
* * * * *