Note: Descriptions are shown in the official language in which they were submitted.
106()S99 : ~
This invention refers to a filling material for
paddings, supports or the like, to a padding filled with
such a filling material and to a process for the production
of such a padding. The invention is particularly concerned
with a filling for a padding or the like, as well as with a
padding containing such a filling serving for the adaptation
of various articles, such as trusses, corsets, girdles, pro- ~-
tective helmets, artificial limbs and insertions, which are
to be used on the human body as well as adapting pads, support
pads, safety pads and sealing pads or the like, particularly I -
for shoes.
Up till now, there has not been found a satisfactory
method of comfortably and individually adapting hard objects
to the shapes of the human body and for simultaneously cushion-
ing the supported portion of the human body, as is, for
example, required when adapting and cushioning the outer
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shells of ski boots consisting of rigid cured or thermosetting
synthetic resin. !~
It is known to fit shoes to the foot by pouring into i~
the cavity between the foot and the upper of the shoe a sili-
cone rubber, and vulcanizing or curing said silicone rubber
in presence of the foot (see U.S. Patent Specification !-
3,325,919). Paddings produced in such a manner suffer from
I the drawbacks that they are given a final unalterable shape
and that they can be very heavy.
It is also known to provide pockets or shells in
cavities between rigid objects and the human body and to fill ;
the pockets or shells with small balls of hard thermosetting
phenolic resins to form a padding, the balls being practically
incompressible and being coated with a lubricating agent
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(see U.S. Patent Specification 3,407,406; German published -
Patent ApplicationsDT-OLS 1,485,772 and DT-OLS 2,211,718).
Such padding will assume a shape adapted to the shape of the
cushioned body portion, but will not provide the desired
yielding support because the padding is not elastically de-
formable as is for instance the case with soft synthetic
foamed material. Thus, it ~ecomes necessary to use an addi~
tional foam material in conjunction with the padding.
It has further been proposed to fill paddings, pock- ¦~
ets and other cavities with a paste-like thixotropic substance
having a high viscosity and mainly consisting of polyisobutyl-
ene having a high content of filler material (see German
published Patent Application DT-OLS 1,685,307). Even with
this padding, the padding effect is very slight because the
filling material present in such a padding cannot be compressed 5
so as to be restored when dynamic pressure is applied to the
padding. Thus, also in this case, a compressible padded layer
is required in addition to the padding.
According to a further proposal, paddings for body
portions are produced from polyurethane foam, thereby provid-
ing the required adaptation by introducing the required reac-
tants into the existing cavity (see German Patent Specifica-
tion DT-PS 901,471). This proposal suffers from the drawback
that any individual fitting must take place in situ, which is
dangerous in view of the high toxicity of the isocyanates
from which the polyurethane foam is made, and in view of the ¦;-
heat of reaction wh~ch is evolved. Furthermore, this method
often leads to faulty fittings which are difficult to remove.
A further disadvantage is that the polyurethane foam is sensi-
tive to perspiration and hydrolysis and soon loses its resil
ience under their influence. ''
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1060599
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It is also known to fill paddings with scraps of
soft resilient foam in the form of sheets or discs having a
large surface area (see German published Patent Application
DT-AS 1,010,825). The desired individual adaptation to exist~
ing shapes of body portions cannot be effected with such a
padding because the soft foamed material, in this case a poly-
urethane foam, is neither thermoplastic nor thermoelastic.
Furthermore, also in this case the padding is subject to -~
deterioration under the action of perspiration and hydrolysis
0 80 that the polyurethane foam used will soon lose its elasticity.
It has also been proposed to fill paddings with
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extruded cord, skein or rope-like fillings consisting of foam-
ed thermoplastic or thermosetting material. E~owever, with !
such paddings it is not possible to effect the desired adapta-
tion to the existing shape of the body portion and at the same
time provide an elastic support for the body portion.
It is further known to use foamed polystyrene in the ~.!
form of flakes, granules or powder as a filling for padded ,i~
cushions and mattresses (see French Patent Specification
1,302,015). Such a foamed polystyrene will lose its elasticity
after being compressed for a long time, so that it cannot be
re-fitted and then no longer has the property of a padding. l.
It is an object of the present invention to avoid
the drawbacks of known filling materials and, respectively,
of paddings filled with such known filling materials, and to
provide a filling for a padding which can be individually
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adapted to a certain shape as often as required and is elasto- -
~meric to the desired extent so that a resilient support may be ~
provided without additional measures. ^
The padding according to the present invention is
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1060599
based on a filling for paddings and supports which consists of
particles of a thermoplastic synthetic resin, preerably hav-
ing a density of 0.02 to 0.3 gm/cc, and according to the inven-
tion the particles are formed, at least in part, of unicellular
bubbles whose outer wall consists of a copolymer of vinylidene
chloride and/or vinyl chloride copolymer, and the hollow inner
core thereof contains a gas, and a skin enclosing said parti- -
cles. It has been found that a filler consisting at least in
part of such bubbles can be easily, for example by supplying
heat, connected into a microfoam-like structure with thermo-
plastic properties, and can be shaped in such a way that the
shape of this structure can be accurately adapted to a certain
form, for example to parts of the body, and the structure also
has the desired elasticity so that it gently pads these parts
of the body. The shape of the filling of the padding according
to the present invention which is formed at first need not be
permanently maintained, but can be varied as desired, so that
thi5 filling can be adapted as frequently as desired, for
example, to certain parts of the body, without any physiologi- ~`
cal harm. Furthermore, the filling of the padding according -
to the invention is light in weight and, in addition, is
resistant against perspiration and hydrolysis. ~ -
The filling of the padding according to the invention
thus is particularly suitable for manufacturing paddings for
patients and invalids, for example, for artificial limbs and
orthopaedic articles of any kind, paddings for wheel-chairs,
sick beds, seats, cushions, beds, supports and so on, and is
also suitable for manufacturing paddings or padded parts for
test drivers, astronauts, racing drivers, sportsmen and
sensitive persons, thus for example for seats, beds or supports
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in spacecraft, test vehicles, cars~ in particular sport cars,
racing boats and aircraft, and also for paddings for shoes of
all kinds, arch supports, chairs and Eeclining furniture,
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knee pads, pads for helmets, diver's goggles, breast prothesis,
and bra paddings.
The bubbles whose resilient outer walls consist of a -
copolymer of vinylidene chloride or of a copolymer of vinyl
chloride are, in contrast to most of the other filling mater-
ials for paddings, non-combustible, so that when combined with
non-combustible padding covers, as for instance asbestos ;
fabric, the filling is particularly suitable for use in
disasters. The non-combustible foam-like filling which is -
thermally insulating, together with the light weight and
exellent padding effect, make it particularly advantageous. -
It has been proved to be of particular convenience if
the outer walls of the bubbles consist of a copolymer of vinyl
chloride and ethylene or of a copolymer of vinylidene chloride -
and acrylonitrile.
According to a further feature of the invention, the
thin casing of the bubbles may consist of copolymers having an
essentially lower softening point than homopolymers whose -
monomers form the main component in terms of volume in the
formation of the copolymer.
In one aspect of this invention there is provided a
conforming padding comprising a material consisting of a
cohered mass formed of discrete hollow resilient thermoplastic
synthetic resin particles and a bonding agent; said discrete
particles having a density of about 0.02 to 0.3 gm/cc and
formed into intact hollow microbubbles having a thin, resi-
lient, gas-impermeable shell enclosing and confining a gas,
said shell consisting of a copolymer of vinylidene chloride
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or of vinyl chloride; said bonding a~ent adherently inter--
connecting said discrete particles into a mobile, resilient,
coherent, plastically deformable mass at body temperature,
said bonding agent having a softening point lower than that
of said shell copolymer and said bonding agent being flowably
plastic at about body temperature and having little plastici~
zing action on said bubble-forming copolymer
In another aspect, the present invention resides in
the combination of a filling material consisting of a padding
as defined in the immediately preceding paragraph, with a
flexible sheath or envelope enclosing said filling material
in a cushion.
In another aspect of this invention there is provided a
method for the production of a padding comprising particles of
a thermoplastic resin having a density of about 0.02 to 0.3
gm/cc., wherein the particles are formed into intact hollow
microbubbles having a thin, resilient, gas-impermeable shell
enclosing and confining a gas, said shell consisting of a
copolymer of vinylidene chloride or of vinyl chloride, and a
material bonding said particles together, and a covering
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~ enclosing said particles, said method comprising introducing
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said bubbles into the covering by means of a carrier substance
via an opening provided in the covering.
The gas present within tbe bubbles may simply be air.
However, in some cases, it may be convenient to use as the gas
ethylene and/or a halogenated hydrocarbon, such as carbon
tetrachloride, and/or a hydrocarbon other than ethylene.
Since vinylidene chloride copolymers and vinvl chloride
copolymers have an extremely low gas permeability, it is
practically impossible for the gas to escape from the closed
bubbles whose
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outer walls consist of such a plastics material. This
property is, above all, of great importance for the rapid
xeturn to shape of the pad after compression and is a pre-
requisite for obtaining the desired comfort of the padding
filled with the filling according to the invention.
For paddings, which in practice will not be subject-
ed to high pressure and which in the first instance are soft
and elastically deformable, it is merely sufficient to fill
the casings or cavities to be padded with the particles form-
ing the filling. However, in the case of paddings which areto retain their shape under normal pressure loads, it is ex-
pedient to join the individual bubbles together. This may be
effected, as already mentioned, by supplying heat wherein, by
suitably selecting the materials for the casing of the bubbles,
the casings may be joined together by body heat supplied to the
bubbles (owing to the position of the padding next to the !
parts of the body to be padded), so that at the same time the
shape of the padding is adapted to these parts of the body.
In order that the bubbles may be more easily joined together,
these bubbles may, according to a further feature of the
invention, be connected by means of an adhesive agent to form
one unit which can preferably be separated again. The soften-
ing point of the adhesive agent is preferably lower than that
of the material of the outer walls of the bubbles, whereby
the outer walls of the bubbles will sinter under the influence
of heat and pressure to produce on cooling a foam-like struc-
ture which can be converted again into individual bubbles by
the application of heat. To provide the desired adhesive -
action, the bubbles may be impregnated with a melt, a solution,
an emulsion or a dispersion of any suitable adhesive substance
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provided it has a broad softening range, such as, for example,
low molecular weight polymers or copolymers, natural or
synthetic resins, natural and synthetic waxes and, above all,
those substances which are used for the preparation of glue
and adhesive melts. Since the melting point of the synthetic
resin materials used for the bubbles of the padding according
to a preferred embodiment of this invention lies in the range
from about 140 to about 195C, depending upon the mixing
proportions of the monomers, the softening range and the
melting point of the adhesive agent should preferably be con-
siderably below this temperature. Particularly suitable ad-
hesive agents are mixed polyamides containing plasticizers and
having a melting point of approximately 68C. It has been
found that most of the known so-called external plasticizers
for pla~tics, lacquers, resins and rubbers meet these require-
ments. Particularly suitable external plasticizers are diethyl-
glycolphthalate, diisooctyl adipate, dibutyl phthalate, dioctyl ;
phthalate, dioctyl sebacate, dibutyl adipate, epoxidized oleic
acid esters, epoxy plasticizers having a molecular weight up
to 2,000, glycerol and polyglycerol, castor oil as well as
many low molecular weight polymers having a molecular weight ;
up to 3,000 such as polyesters of adipic acid and ethylene
glycol or polyethers of triols and propylene oxide, polysilox-
anes, polyolefins, higher alcohols and so on. m ese substan-
ces, which to a certain extent have a slight plasticizing
effect, can be used alone or in mixtures with each other or
with water or with other substances having similar properties
as adhesive agents for joining the individual particles. ¦;
The adhesive agent preferably consists of a sub-
stance which is fluid or paste-like at body temperature, and
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which exerts a slightly softening effect on the bubbles so
that only at body temperature do the bubbles join together
as desired to form a foam-like structure.
In certain fields of application, it is expedient
if the filling according to the invention consists only in
part of the unicellularbubbles with the thin casing of a
resilient vinylidene chloride copolymer or vinyl chloride
copolymer, which are mixed with other synthetic resin particles.
In this case, according to a preferred embodiment of the inven~
10 tion, the bubbles are surrounded by another polymer matèxial. i
Furthermore, larger particles of foam, for example foamed
spherical particles consisting of amorphous synthetic resins
and having a closed-cell structure, may be added together with
the bubbles as a filling for the padding. The minute uni-
cellular bubbles thus fill up practically all the cavities
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; which are formed between the larger particles, and in the li`
event of a mechanical pressure being applied from the outside, ;~
the thin casing of the bubbles will be subjected to a uniform
pressure from all sides. The effect of forming an uneven
texture on the surface of the thin padding covers, which dis-
advantageously occurs when using the abovementioned iarger
spherical foam particles consisting of amorphous synthetic
resin, i8 removed by using the minute bubbles. 1~`
In addition to synthetic resin particles, other
materials such as fibres, rubber particles or the like may ~`~
also be used as filling in conjunction with the bubbles.
~; Different materials such as leather, synthetic
leather, fabrics or fleeces may also be considered as casings
~; or coverings for the filling of the padding according to this
invention, depending upon the purpose for which it is to be
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used. The bubbles are preferably surrounded by a cover which
is at least partially permeable to air and water.
This filling of the padding according to the inven- ;
tion can obviously be introduced through an opening in the
casing of the padding, whereupon the opening is closed.
According to a method of the invention for producing a padding
according to this invention, the bubbles and, if required,
other additives, are inserted through an opening in the
padding cover by means of a preferably fluid carrier substance.
In this case, the filling material can, for example, be intro-
duced into the cover of the padding together with the fluid
carrier substance by means of a thin hollow needle, as is
for instance used as an injection needle for medical purposes.
The cover may be pierced at any desired location by means of
this hollow needle.
After the bubbles have been introduced into the
padding cover, the carrier substance, if liquid, is preferably
evaporated off. This can, for example, be effected in a i`
circulating warm air oven.
It is of particular advantage to use as the carrier
substance an adhesive agent which, after the bubbles have ¦;
been added, causes them to combine in the desired shape into
a micro-foam. The carrier substance used can, for instance,
be a higher alcohol or an epoxy plasticizer.
According to a further feature of the inventive
process, the bubbles may be formed after being introduced by li
means of the carrier subst2rce, as particles containing an
expanding agent which are inflated, preferably by the applica-
tion of heat.
After having been introduced into the padding cover,
the particles which have not been foamed and containing, as a
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~ 60599
rule, as an expanding agent carbon tetrachloride, ethylene or
a hydrocarbon other than ethylene, can be made to expand by
means of a heat source between +75C and +160C, and thus
changed ~nto bubbles. For this purpose, fluid baths heated
to a temperature between +85C and +110C are most suitable
in view of their capacity of rapid heat transfer to the
particles which have not been foamed, and particularly in
those cases in which -- as is preferred -- the padding casings
used are permeable to fluids.
Parts of normal thickness, such as parts for artifi-
cial legs or sports shoes, with a thickness of 1.5 to 3.5 cm
in the finished foam state, are ready in less than 20 seconds.
In the case of permeable casings, hot steam is proposed for a
partial foaming, as for example in the case of large articles,
and infrared irradiators are proposed in the case of non-
permeable padding casings.
According to a further feature of the inventive
procbss, the carrier substance may consist of an inert liquid,
for example water, preferably including hygroscopic additives. ~
When using water, the water may contain a plasticizing com- $
ponent, for example glycerol acting as an adhesive agent.
The padding of this invention has the advantage of ~-
having a low density, so that, in the event of a dynamic load,
the low density causes reduced inertia forces since the ;`
kinetia energy and the centrifugal force are directly propor- ,
tional to the mass moved. ~he reduced forces of inertia
result in reduced wear and a saving in drive energy so that
it is possible to provide a padding of simpler construction
as well as a padding of lighter weight -- an advantage which
is particularly appreciated by persons who wear artificial `
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106~599
limbs and also sportsmen and athletes.
A further advantage of the padding according to
this invention is that, in the event of compression, the
filling behaves in a similar manner to air enclosed in a gas-
tight resilient covering. This effect results from the fact
that the gas-filled bubbles first try, on exertion of pressure,
to escape sideways away from the point of compression, before
they themselves are elastically compressed. This property is
desired in numerous paddings and becomes of still greater
importance if it is considered that the padding casings need
not be impermeable as is the case with an alr or liquid ;
filling, but can be constructed so as to be permeable and
therefore breathe. The softness, adaptability, reversible
compressibility, density and numerous other properties of the
filling of the padding according to this invention can be
varied extensively by varying the type and ~uantity of the ~ ~
adhesive agent used. In general, 65 to 450 grams of adhesive ~ -
agent are used for a finished padding volume of 3,500 cc.
The filling of the padding according to this invention pre-
ferably has a density of 0.02 to 0.3 gm/cc, but can, in
certain cases, also have a higher density, particularly in
those cases in which, in addition to the bubbles, other
particles of larger size are provided within the filling.
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