U.S. patent number 3,905,376 [Application Number 05/411,099] was granted by the patent office on 1975-09-16 for pedicure prosthesis for the metatarsal arch of the foot.
This patent grant is currently assigned to Amos N. Johnson. Invention is credited to Richard D. Gilbert, Amos N. Johnson.
United States Patent |
3,905,376 |
Johnson , et al. |
September 16, 1975 |
Pedicure prosthesis for the metatarsal arch of the foot
Abstract
A support for the metatarsal arch of the foot is formed by
injection of a self-curing non-foamable fluid material into the
arch support enclosure. This fluid material automatically cures
into a rigid support or prosthesis for the arch of the foot. This
polymerizable material is normally contained in either a insert
under the foot or by a balloon-like material, in either case the
polymerizable material is pumped or injected into the resulting
enclosure. The same method can be used to form in situ prosthesis
casts for any part of the body, that is, to form splints, braces,
etc., contoured directly to the portion of the human body for which
it is designed to lend support. The self-curing material is
preferably a cross-linkable prepolymerized material which includes
an initiator, and the self-curing is achieved by the application of
mild temperatures, i.e., not greater than 120.degree.F. Also, the
self-curing can be achieved by the application of actinic
radiation.
Inventors: |
Johnson; Amos N. (Garland,
NC), Gilbert; Richard D. (Raleigh, NC) |
Assignee: |
Johnson; Amos N. (Garland,
NC)
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Family
ID: |
26861530 |
Appl.
No.: |
05/411,099 |
Filed: |
October 30, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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165610 |
Jul 23, 1971 |
3782390 |
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Current U.S.
Class: |
36/154; 264/222;
602/7; 264/DIG.30; 264/46.6; 264/313; 264/443; 264/496 |
Current CPC
Class: |
A61L
15/07 (20130101); A61F 13/04 (20130101); A43B
7/28 (20130101); A43B 1/0036 (20130101); Y10S
264/30 (20130101) |
Current International
Class: |
A43B
7/14 (20060101); A43B 7/28 (20060101); A61F
13/04 (20060101); A61L 15/00 (20060101); A61L
15/07 (20060101); A61F 005/14 () |
Field of
Search: |
;128/595,90,89
;264/222,45,DIG.30 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Yasko; J.
Attorney, Agent or Firm: Christen & Sabol
Parent Case Text
This is a continuation-in-part of U.S. Ser. No. 165,610, filed on
July 23, 1971 now U.S. Pat. No. 3,782,390.
Claims
What is claimed is:
1. The process for preparing a prosthesis for supporting or
restraining a part of the body which comprises: (a) placing a
fluid, curable, non-foamable material in a prosthesis enclosure,
said fuid self-curable material being comprised of an admixture of
a cross-linkable prepolymerized material and an ethylenically
unsaturated monomer, and (b) curing in situ said fluid curable
material at a temperature between 59.degree. and 120.degree.F. to
form a rigid cured material which conforms to the shape of the
affected portion of the body and which has essentially the same
volume in the pre-cured states as in the cured state, there being
no gas given off during the curing.
2. The process of claim 1 wherein said fluid, curable, non-foamable
material is a self-curing material, and wherein said self-curing
material is permitted to cure in situ.
3. The process of claim 1 wherein said prosthesis enclosure is
first placed in a shoe, wherein said affected part of the body is
the metatarsal arch of a foot, and wherein said prosthesis
enclosure is placed on the affected portion of said body by placing
said foot in said shoe.
4. The process of claim 1 wherein pressure is placed on said fluid
self-curing material before it completely cures so that said fluid
self-curing material takes the shape of metatarsal arch.
5. The process of claim 1 wherein said prosthesis enclosure is a
sealed envelope, with at least its top surface being elastic,
wherein said fluid self-curing material is placed in said
prosthesis enclosure by piercing a side of said prosthesis
enclosure with an elongated, hollow tube device and force injecting
said fluid self-curing material through said elongated, hollow tube
device into said prosthesis enclosure, and wherein said hollow tube
device is removed after said fluid self-curing prosthesis enclosure
and said side of said prosthesis enclosure is rapidly sealed.
6. The process of claim 5 wherein said region of said shoe of said
prosthesis enclosure which is placed by said hollow tube device is
self-curing.
7. The process of claim 1 wherein said prosthesis enclosure is a
rigid insert that is placed on or affixed to the insole of said
shoe, said insert comprising a flat plate that extends across the
width of said insole and extends lengthwise at least across the
metatarsal arch of said foot, a low side wall on the side away from
said metatarsal arch which completely covers said arch when said
foot is inserted in said shoe, said foot serving as the top of said
prosthesis enclosure, wherein said fluid self-curing material is
placed in said prosthesis enclosure by means of a tube inserted
between said high side wall and said foot, and wherein said tube is
rapidly removed after said fluid self-curing material is placed in
said prosthesis enclosure.
8. The process of claim 2 wherein said self-curing material is an
admixture of an acrylate ester monomer, an acrylate ester
prepolymer and an activated free-radical initiator.
9. The process of claim 8 wherein said admixture also contains a
plasticizer.
10. The process of claim 2 wherein the self-curing material is an
admixture of (i) polymethyl methacrylate and a cross-linking agent,
such having been pre-polymerize to just below the gel point, (ii)
methyl methacrylate and (iii) an activated free-radical
initiator.
11. The process of claim 2 wherein the self-curing material is an
admixture of styrene, a carboxylated monomer, a carboxylated
bimonomer of prepolymer, and a polyvalent salt curing agent.
12. The process of claim 1 wherein said curing is achieved by means
of actinic radiation.
13. The process of claim 1 wherein said curable material contains a
filler.
14. The prosthesis for supporting or restraining a part of the body
which consists of a prosthesis enclosure adapted to be placed on
the affected part of the body and a rigid, cured, non-foamed
material, within the prosthesis enclosure, said rigid, cured,
non-foamed material comprising a prepolymerized material
cross-linked by an ethylenically unsaturated monomer, said rigid,
cured, non-foamed material having been cured at a temperature
between 59.degree. and 120.degree.F., said rigid, cured, non-foamed
material being adapted to conform to the shape of the affected
portion of the body, and said rigid, cured, non-foamed material
having essentially the same volume in the cured state it had in the
pre-cured state.
15. The prosthesis of claim 14 wherein said prosthesis enclosure is
located on the insole of a shoe where the metatarsal arch of a foot
is located.
16. The prosthesis of claim 15 wherein said prosthesis enclosure is
a sealed enclosure.
17. The prosthesis of claim 16 wherein said prosthesis enclosure is
a rigid insert that is placed on or affixed to said insole of said
shoe, said insert comprising a flat plate that extends lengthwise
across the width of said insole and extends lengthwise at least
across the metatarsol arch of said foot and a low side wall on the
side away from the metatarsol arch which completely covers said
arch when said foot is inserted in said shoe, said foot serving as
the top of said prosthesis enclosure.
18. The prosthesis of claim 17 wherein said prosthesis enclosure is
comprised of aluminum.
19. The prosthesis of claim 14 wherein said curable material
contains a filler.
20. The process for preparing a prosthesis for supporting or
restraining a part of the body which consists of: (a) placing a
fluid, curable non-foamable material in a prosthesis enclosure,
said fluid self-curable material being comprised of an admixture of
a cross-linkable prepolymerized material and an ethylenically
unsaturated monomer, and (b) curing in situ said fluid curable
material at a temperature between 59.degree. and 120.degree.F. to
form a rigid cured material which conforms to the shape of the
affected portion of the body and which has essentially the same
volume in the pre-cured state as in the cured state, there being no
gas given off during the curing.
21. The prosthesis for supporting or restraining a part of the body
which consists of a prosthesis enclosure adapted to be placed on
the affected part of the body and a rigid, cured, non-foamed
material, containing a filler or a plasticizer or both, within the
prosthesis enclosure, said rigid cured, non-foamed material
comprising a prepolymerized material cross-linked by an
ethylenically unsaturated monomer, said rigid, cured, non-foamed
material having been cured at a temperature between 59.degree. and
120.degree.F., said rigid, cured, non-foamed material being adapted
to conform to the shape of the affected portion of the body, and
said rigid, cured non-foamed material having essentially the same
volume in the cured state it had in the pre-cured state.
Description
PRIOR ART
Foamed thermoplastic material used as prosthesis are known.
U.S. Pat. No. 3,257,742 shows a soft readily deformable foot
support for shoes. The support has a plastic or putty-like
consistency and is a foot support that is readily impressionable in
response to pressure exerted thereon by the foot. After the foor
pressure is removed, the support returns to its original shape. The
support is essentially a cured epoxy resin or linear polybutadiene
that has these characteristics, and an outer encompassing layer,
such as, leather, at col. 3, lines 73 to 74, the uncured resins are
stated to be flowable so that they take the shape of the container
into which they are poured. This patent does not disclose in situ
curing in a shoe to set up a permanent foot support that is tailor
molded in effect to aid each foot problem. The patent further
discloses the use of a hard non-foamed prosthesis.
Likewise with U.S. Pat. No. 3,402,411 which is drawn to a ski-boot
ankle support and the use of polymers which lend themselves to
ready molding when pressure is applied with slow shape
recovery.
U.S. Pat. No. 3,407,406 is directed essentially to a ski-boot and
it uses a flexible, hollow material filled with a substance which
holds its shape a lone time or until an outside pressure is
exerted. The patent does not disclose a non-foamable prosthesis
which is prepared from a self-curing polymerizable material.
U.S. Pat. No. 3,089,486 discloses using a flexible bandage
impregnated with a curable, monomer-treated, polymer to form a
cast. The monomer can be a methacrylate monomer, i.e., methyl
methacrylate monomer. The polymer can be a methacrylate polymer,
such as, polymerized methyl methacrylate. The monomer that is added
also contains a promoter; and the polymer is plasticized and
contains a polymerization catalyst. The polymer is plasticized with
"honey" -- it can also contain a secondary plasticizer (to stablize
the honey, etc.). High percentages of honey are used. The patent
calls the honey an "essential constituent" and is credited with
enabling the curing to take place at room temperature. The patent
states that there have been prior attempts to use methacrylate
polymers and methacrylate monomers, but such attempts have been
unacceptable to the art. In the patent system, the methacrylate
polymer is placed on the flexible bandage and dried and then the
liquefied admixture of methacrylate monomer, promoter, etc., are
added to the methacrylate monomer. The patent states that the
methacrylate polymer and methacrylate monomer cure at low
temperatures. Maximum curing temperatures of 101.degree. to
108.degree.C. are shown -- see Table III. Curing can be accelerated
by applying heat with an infra-red element. The patent states that
a protective barrier is first applied to the injured body member
"in order to protect the member from skin irritating fumes and/or
seepage from the monomer component." The protective barrier
normally would involve the unsatisfactory procedure of wrapping a
strip of material several times around the arm, with the constant
danger of skin damage from fumes or seepage. A tubular sheath can
be used but such involves the possibility of irritating folds
developing as the curable resin impregnated webbing is wrapped
around the body member. The patent speaks of removal of the
protective layer by cutting the cast and then bending the cast back
together. The patent states that a cushion layer can be used
between the cast and the skin. Application of the curable resin
impregnated bandage is also unsatisfactory. It is wet, messy and
gloves must be used to handle it. If it touches anyone's skin,
there can be skin irritation or damage.
U.S. Pat. No. 3,215,137 involves a cast bandage scheme that cures
at a low temperature, but it suffers from many of the above
disadvantages. The patent bases its invention on the use of certain
special acetate diluents, the purpose being to reduce the heat let
off by the polymerizations (which are strongly exothermic). The
monomers are certain polyhydric alcohol esters of specific dimethyl
acrylates. A powdered polymer or other filler is used. The curable
resin composition is impregnated on gauze, with the numerous
problems therewith arising when the impregnated gauze is used to
form a cast.
U.S. Pat. No. 3,032,033 uses an air- or non-cured liquid resin, but
does not specify what it is. Such resin is used on fiber glass
cloth; an inner sponge rubber liner is used.
U.S. Pat. No. 3,630,194 discloses an orthopedic cast which starts
with a flexible fabric carrier supporting a dry cast-forming
composition comprised of at least 9 percent of particular solid,
water-soluble vinyl monomers. The fabric is immersed in water
containing a polymerization initiator for the vinyl monomer. The
water should be at least 110.degree.F., and preferably is
120.degree. to 130.degree.F. Care has to be taken in order to avoid
contact with the skin or else buffers may have to be used. The
requirement of using a wet fabric is messy and dangerous to one's
skin and health. Also, there is the problem of removal of the water
after hardening of the vinyl monomer.
Cast have been made from web wrappings which are impregnated with a
photocurable resin. The curing is done by exposure to actinic
radiation, to produce a rigid cast. Such systems are essentially
impossible to use in preparing shoe prosthesis. Such impregnated
web wrappings generally contain soft underlying layer, and other
protective and cushion-type layers. The impregnated web wrappings
are used to allow dispersion of heat during the curing step and air
circulation during use of the cast. In one particular system, a
polypropylene stockinette is placed over the skin, then a
polypropylene web wrap is placed over the polypropylene stockinette
to cushion bony prominences; a webbed fiber glass impregnated with
a specific UV sensitive plastic resin is applied over the web wrap,
and the resin is hardened by a 3-minute cure under a UV lamp. This
system is marketed under the tradename "Lightcast II."
Ultrasonic curable resins have also been used.
The various references cited in this prior art section have a
number of disadvantages and negative teachings which are not dealt
with herein due to space conditions.
Attention is drawn to U.S. Pat. Nos. 3,674,021, 3,375,822,
3,373,741, 2,952,082, 2,119,590, 3,048,169, 3,325,919, 3,293,663,
3,067,431, 3,121,430, 3,631,854, 3,585,639, 3,477,968, 2,086,242,
3,613,675, 3,669,708, 3,618,599, 3,421,501, 3,566,487, 3,415,243
and 3,656,475.
BROAD DESCRIPTION OF THIS INVENTION
The invention involves a process for preparing a prosthesis for
supporting or restraining a part of the body. The process, broadly,
involves placing a prosthesis enclosure on the affected portion of
the body; placing a fluid, curable, non-foamable material in the
prosthesis enclosure; and curing in situ the fluid curable material
to form a rigid cured non-foamed material which conforms to the
shape of the affected portion of the body.
Preferably a self-curing material is used, and preferably such
utilizes a prepolymer scheme. The most preferred fluid self-curing
material is polymethyl methacrylate dissolved in monomeric methyl
methylacrylate (1:1 weight ratio), and the material contains about
0.1 percent of an acyl peroxide as a catalyst (initiator).
In one embodiment, the prosthesis enclosure is first placed in a
shoe, wherein the affected part of the body is the metatarsal arch
of a foot and wherein the prosthesis enclosure is placed on the
affected portion of the body by placing the foot in the shoe.
Preferably, pressure is placed on or applied to the fluid
self-curing material before it completely cures so that the fluid
self-curing material takes the shape of the metatarsal arch. The
pressure can be applied by the weight of the body being shifted
onto the foot. One sub-embodiment involves a prosthesis enclosure
which is a sealed envelope with at least its top surface being
elastic. In that sub-embodiment the fluid self-curing material is
placed in the prosthesis enclosure by piercing a side of the
prosthesis enclosure with an elongated hollow tube device and force
injecting the fluid self-curing material through the elongated
hollow tube device into the prosthesis enclosure. The hollow tube
device is removed after the fluid self-curing material is placed in
the prosthesis enclosure and the side of the prosthesis enclosure
is rapidly sealed. Preferably the region of the side of the
prosthesis enclosure, which is pierced by the hollow tube device,
is self-sealing when the hollow tube device is removed.
In another sub-embodiment, the preferred embodiment of the
invention, the prosthesis enclosure is a rigid insert that is
placed on or affixed to the insole of the shoe. The insert
comprises: a flat plate that extends across the width of the insole
and extends lengthwise at least across the metatrasal arch of the
foot; a low side wall on the side away from the metatarsal arch;
and a high side wall which completely covers the arch when the foot
is inserted into the shoe. The foot serves as the top of the
prosthesis enclosure. The fluid self-curing material is placed in
the prosthesis enclosure by means of a tube inserted between the
high side wall and the foot. The tube is rapidly removed after the
fluid-curing material is placed in the prosthesis enclosure.
In still another sub-embodiment of the invention, a cast is placed
over the prosthesis enclosure before the fluid self-curing material
is placed in the prosthesis enclosure. This sub-embodiment can be
used whenever a cast is used, for example, with broken limbs.
The invention also involves the prosthesis for supporting or
restraining a part of the body. The prosthesis includes a
prosthesis enclosure on the affected part of the body and a rigid,
polymerized, non-foamed material, within the prosthesis enclosure,
which conforms to the shape of the effected portion of the body.
The prosthesis can be one where the prosthesis enclosure is located
between the affected part of the body and a cast. The prosthesis
can be one where the prosthesis enclosure is located on the insole
of a shoe where the metatarsal arch of a foot is located. This
latter prosthesis can be one where the prosthesis enclosure is a
sealed enclosure. Or, preferably, this latter prosthesis can be one
where the prosthesis enclosure is a rigid insert that is placed on
or affixed to the insole of the shoe. The insert comprises a flat
plate that extends across the width of the insole and extends
lengthwise at least across the metatarsal arch of the foot; a low
side wall on the side away from the metatarsal arch; and a high
side wall on the side of the metatarsal arch which completely
covers the arch when the foot is inserted in the shoe. The foot
serves as the top of the prosthesis enclosure.
This invention also involves the use of resins or polymers which
are cured or polymerized by exposure to actinic radiation.
One advantage of actinic radiation (e.g., U.V. light) curing
systems is that it does not require the use of heat. Also, a
catalyst does not have to be added to the curable resin material
before it is placed in the prosthesis enclosure (although
accelerators and/or catalysts can be used).
This invention also involves the use of resins or polymers which
are cured or polymerized by exposure to ultrasonic energy.
This invention forms rigid, physiologically inert, integral
devices.
The prosthesis, when used as a cast for broken bones, must be rigid
(once cured) in order to maintain the bones in proper position
throughout the healing process. In other instances, it is also
crucial that the prosthesis (once cured) must be rigid, and not
have any significant cold flow.
When using this invention, the surgeon, too, can begin at once to
fix the limb in the set position, and does not have to work with a
slippery, pastey, or generally messy material such as
plaster-of-paris or wet curable-resin impregnated web bandages.
This invention generally uses an enclosed prosthesis into which the
curable-resin is placed. This keeps the monomers, prepolymers,
etc., from touching the skin, thereby preventing skin irritation,
skin burns, skin allergy reactions and sensitization. As
curable-resin materials are used which do not give off gas or
fumes, there is no pressure build up problem.
The use of resins as the prosthesis material generally means a
reduction of the weight, when compared to such prosthesis materials
as plaster of paris. This allows the patient to be more mobile.
Most of the cured prosthesis materials of this invention have
excellent X-ray transmitting properties.
A crucial feature of this invention is the use of resins or
polymers which do not exceed a physiologically acceptable
temperature (120.degree.F or below) during the curing or hardening
of the resin or polymer. The use of such a temperature prevents
unpleasant burns and allows the patient to keep on the prosthesis
during curing.
This invention can be used for casts for deformed hands (arthritis)
or back braces (it is essentially impossible to properly contour
steel or aluminium).
As used herein, unless otherwise specifically stated, an alkyl
group contains 1 to 6 carbon atoms, an aryl group contains 6 to 18
atoms, and an alkaryl group or an aralkyl group, wherein alkyl and
aryl are defined as above.
DETAILED DESCRIPTION OF THE INVENTION
The objects and advantages of the invention become apparent to
those ordinarily skilled in the art in the following description of
the invention as illustrated in the accompanying drawing, in
which:
FIG. 1 is a top view of the prosthesis of this invention;
FIG. 2 is a cross sectional view of one embodiment of preparing the
prosthesis;
FIG. 3 is a partial perspective view of another embodiment of this
invention, namely, the balloon-like enclosure;
FIG. 4 is a partial perspective view illustrating the injection of
the polymerized material into the balloon-like enclosure; and
FIG. 5 is a partial perspective view illustrating the preparation
of a prosthesis which in effect is an arm cast.
FIG. 1 illustrates a rigid non-foamed arch support 4 and the
transverse or metatarsal arch of the foot. FIG. 2 illustrates the
embodiment of the invention where the prosthesis is produced in
situ. Foot 8 is inserted into shoe 12. Shoe 12 contains prosthesis
enclosure 16 which consists of base plate 20, side plates 24 and
28. Prosthese enclosure 16 fits into the bottom of shoe 12 so that
when foot 8 is inserted into shoe 12 the metatarsal arch is
completely enclosed by prosthesis enclosure 16. Base plate 20 must
be wide enough and long enough so that the circumference areas of
the arch are in contact therewith so that a seal is formed between
foot 8 and base plate 20. The bottom surface of base plate 20 can
contain an adhesive to allow prosthesis enclosure 16 to adhere to
the inner sole and remain in the desired position. Side plate 28 is
located on the outer extermity on the foot, forming a seal by
contacting the side surface of the sole. Side wall 24 is located at
the inner extremity of the foot, contacts the side of the foot, and
is so shaped as to form a seal with the side of the foot. Self
curing material 32 is injected into the area enclosed by prosthesis
enclosure 20 and foot 8. Material 32 is injected by means of tube
36, the tip of which is inserted into the enclosure between side
wall 24 and foot 8 as shown in FIG. 2. Material 32 is pumped into
the enclosure between foot 8 and piece 16 as shown in FIG. 2. The
entire enclosure is filled up with material 32 and the tip of tube
36 is removed. Material 32 is then self polymerizable, forming in
situ a non-foamable rigid prosthesis which conforms to the
metatarsal arch and gives excellent support thereof. The form and
shape of the metatarsal arch support prosthesis is determined by
the contours of the foot of the wearer who is exerting pressure on
the prosthesis as, or immediately after, the self-curing fluid
system is injected (before complete curing).
Another embodiment of the invention is illustrated in FIGS. 3 and
4. Prosthesis enclosure 40 is illustrated in a deflated condition
in FIG. 3. Prosthesis enclosure 40 is a completely sealed unit and
is placed in the shoe in a manner so that it is under the entire
metatarsal arch and surrounding foot portion. Enclosure 40 is made
of a deformable material at least part of which is self-sealing
after puncture by a sharp object. Any self-sealing material may be
used which is compatable with the foot and the self-curing
material. While the self-sealing portion is preferred, the puncture
area can be sealed by known methods such as those given in U.S.
Pat. Nos. 2,646,707 and 2,803,284 which provide means for injecting
self-curing material 44 into the internal space of enclosure 40 by
means of a hollow sharp pointed instrument 48. Any sharp hollow
pointed instrument, such as, a hypodermic needle, can be used for
puncturing enclosure 40 and force injecting self-curing material 44
into the internal space of enclosure 40 so that it maya cure to
form a rigid non-foamable prosthesis. The bottom surface of the
arch support prosthesis may be coated with an adhesive to allow the
device to be attached to the inner sole securely enough to remain
in the desired position in the footwear.
FIG. 5 illustrates the universality of using this invention to form
a rigid supporting conformed non-foamable prosthesis whereever any
cast or similar enclosure is used on a human or animal. FIG. 5
specifically illustrates the use of the prosthesis in conjunction
with cast 52 on limb 56. Cast 52 can be made of any conventional
cast material, such as, plaster of Paris, or can be a relatively
deformable or elastic material, such as, rubber. Between limb 56
and cast material 52, a prosthesis enclosure such as 40 in FIG. 3
is inserted and encompasses all or part of limb to illustrate this
variation of this invention. Prosthesis enclosure 60 can be
elongated and wrapped around limb 56 before cast 52 is applied or
it can be doughnut shaped and inserted over limb 56 before case 52
is applied. The self-curing material is injected into prosthesis
enclosure 60 by means of a hypodermic needle 64. Cast 52, when it
is relatively elastic or when it is rigid, acts in effect as a
restraining force which causes the formed prosthesis to conform to
the outline of the limb. Thus, if the limb has been broken, it is
in effect a cast which is superior to any known cast. The
self-curing material which is used herein should broadly be a
thermoplastic or thermoset material which polymerized or cures in
situ after being placed in the prosthesis enclosure, should not
give off any gas during curing, should be gaseous or liquid, should
have the same volume in the prepolymerized states as in the
resulting polymerized state (i.e., as after curing), and which
should be nontoxic or nonharmful to human or animals, particularly
the effected skin area. The term self-curing material encompasses
an admixture of any cross-linkable prepolymerized material and any
ethylenically unsaturated monomer which does not cure to any
substantial degree until the admixture is placed in the prosthesis
enclosure. This encompasses curable systems which are admixed with
a catalyst and immediately injected into the prosthesis
enclosure.
The self-curing material can be replaced by any actinic
radiation-curable material. The term actinic radiation-curable
material encompasses an admixture of any cross-linkable
prepolymerized material and any ethylenically unsaturated monomer
which does not cure to any substantial degree until the admixture
is placed in the prosthesis enclosure and exposed to actinic
radiation. The curing environment and the curing material should
not involve any temperature exceeding 120.degree.F.
At least a portion of the prosthesis enclosures, such as, 40 and
60, need to be transparent or translucent (colored, white, clear or
opaque) so that the actinic radiation-curable material can be
exposed to actinic radiation.
The cross-linkable prepolymerized materials are broadly unsaturated
polymerizable materials which are generally conventional classes of
known resins such as unsaturated polyester resins, acrylic resins
and the like which that have unsaturation either in the polymer
backbone or in the side groups.
The preferred cross-linkable prepolymerized materials are the
poly(esters of methacrylate), and the preferred poly(ester of
methacrylate) is poly(methyl methacrylate.
Any of the ethylenically unsaturated monomers listed below [(1) and
(6)] can be prepolymerized to be used as the cross-linkable
material.
The most preferred polyester resins are prepared by the
esterification of alpha, beta-unsaturated polybasic acids,
(preferably a dibasic acid) and a polyhydric alcohol (preferably a
dihydric alcohols). Certain compounds of this type may be indicated
generacally as follows:
--M--G--M--G--M--G, where --M-- represents an unsaturated dibasic
acid residue and --G-- represents a dihydric alcohol residue.
Modifying saturated dibasic acids may also be used in the polyester
resin compositions. Representative dihydric alcohol and unsaturated
polybasic acids are shown below.
In preparing unsaturated polyester which may be employed in the
practice of the present invention, the alcohol component may
comprise one of the group of solid polyethylene glycols designated
as "Carbowax." Polyethylene glycols such as the Carbowaxes are
understood to have molecular weights above 300. Those most useful
for this invention have weights below 4000 and preferably are in a
range of about 1000 to 2000, e.g., 1500.
Examples of dihydric alcohols are propylene glycol, ethylene
glycol, trimethylene glycol, 2,2-dimethyl-propanediol,
1,2-butanediol, 2,3-butanediol, 1,3-butanediol, 1,4-butanediol,
1,5-pentanediol, 3-methyl-1,3-butanediol, pinacol,
2-methyl-2,4-pentanediol, 1,5-hexanediol, 1,8-heptanediol,
1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,
1,11-hendecanediol, 1,12-dodecanediol, 1,13-tridecanediol,
1,14-tetradecanediol, 1,15-pentacanediol, 1,16-hexadecanediol,
1,18-octadecanediol, 1,24-tetracosane and 1,30-tricacontanediol.
Examples of trihydric alcohols are glycerol, 1,2,3-butantriol and
1,1,-trihydroxymethylethane. Examples of higher polyhydric alcohols
are 1-1,2,3,4-butanetetrol, tetrahydroxyneopentane, D-arabitol,
adonitol, L-arabitol, xylitol, sorbitol, D-mannitol, o-ioditol,
dulcutol, L-tatitol, styracitol, perseitol, volemitol, cellobiitol,
lactitol, melibiitol and maltitol.
The acid component usually comprises an alpha, beta-ethylenically
unsaturated polycarboxylic acid such as maleic, fumaric or itaconic
acid, or the well-known derivatives of these polycarboxylic acids
having ethylenic unsaturation in alpha-beta relation to the
carboxyl group. Polybasic acids such as aconitric acid,
tricarballyic acid or citric acid may also be employed. A plurality
of such acids may also be mixed with each other, if so desired. In
many instances, it may be desirable to include a dicarboxylic acid
free of ethylenic unsaturation. Examples of this latter type of
dicarboxylic acid include phthalic acid or terephthalic acid,
which, although they contain double bonds in the benzene ring, do
not undergo addition reaction with monomer compounds and may,
therefore, be considered as being the equivalent of saturated
compounds. Likewise, aliphatic dicarboxylic acids such as succinic
acid, adipic acid, sebacic acid, or azelaic acid, may be
substituted for a part of the alpha, beta-ethylenically unsaturated
dicarboxylic acid. The proportion of the non-ethylene acid with
respect to the alpha, betaethylenically unsaturated acid is
susceptible of wide variation. A molecular proportion of 0.25 to 12
moles of saturation acid per mole of unsaturated acid is usually
used for commercial applications. Also acid anhydrides of these
dicarboxylic acids can be used instead of the dicarboxylic
acids.
The cross-linked prepolymerized materials can be prepared by any
conventional method. In preparing the polyester, a small excess
(usually 5 or 10 percent) of the dihydric alcohol is usually
employed. The conditions of the esterification reaction are those
conventionally employed in preparing polyesters. For example, the
mixture of the alcohol and the acid is heated in a vented container
or under an inert atmosphere until the water of reaction is
expelled from the system, which usually occurs in a temperature
range of about 150.degree. to 210.degree.C. The reaction is
continued until the acid value is reduced to a reasonable low
point, e.g., within a range of about 5 to 50, or until the mixture
becomes highly viscous or even solid when it is cooled. Usually
these conditions are attained in a period of 2 to 20 hours. In any
event the reaction is concluded before the product becomes
infusible and insoluble because of the advanced stage of
polymerization. The product is then blended with the ethylenically
unsaturated monomer in such a manner as to maintain the temperature
of the blend below 150.degree.F.
The preferred ethylenically unsaturated monomers which can be used
as the cross-linking agent are the esters of methacrylate and the
most preferred is methyl methacrylate.
The ethylenically unsaturated monomers which can be used as the
cross-linking agent may be selected from the following general
list:
(1) Monoolefinic hydrocarbons, that is, monomers containing only
atoms of hydrogen and carbon, such as styrene, alpha-ethyl styrene,
alpha-butyl styrene, vinyl toluene and the like.
(2) Halogenated monoolefinic hydrocarbons, that is, monomers
containing carbon, hydrogen and one or more halogen atoms such as
alpha-chlorostyrene, alpha-bromostyrene, 2,5-dichlorostyrene,
2,5-dibromostyrene, 3,4-dichlorostyrene, 3,4-difluorostyrene,
ortho-, meta and para- fluorostyrenes, 2,6-dichlorostyrene,
2,6-difluorostyrene, 3-fluoro-4-chlorostyrene,
2,4,5-trichlorostyrene, dichloromonofluorostyrene, chloroethylene
(vinyl chloride), 1,1-dichloroethylene (vinylidene chloride),
bromoethylene, fluorethylene, iodoethylene, 1,1-dibromoethylene,
1,1-difluoroethylene, 1,1-diiodoethylene and the like.
(3) Esters of organic and inorganic acids such as vinyl acetate,
vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl
valerate, vinyl caproate, vinyl enanthate, vinyl benzoate, vinyl
toluate, vinyl p-chlorobenzoate, vinyl o-chlorobenzoate, vinyl
m-chlorobenzoate, and similar vinyl halobenzoates, vinyl
p-methoxybenzoate, vinyl o-methoxybenzoate, vinyl p-ethoxybenzoate,
methyl methacrylate, ethyl methacrylate, propyl methacrylate, buty
methacrylate, amyl methacrylate, hexyl methacrylate, heptyl
methacrylate, octyl methacrylate, decyl methacrylate, methyl
crotonate, ethyl crotonate, and ethyl tiglate, methyl acrylate,
ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl
acrylate, isobutyl acrylate, amyl acrylate, hexyl acrylate,
2-ethylhexyl acrylate, heptyl acrylate, octyl acrylate,
3,5,5-trimethyhexyl acrylate, decyl acrylate and dodecyl acrylate,
isopropenyl acetate, isopropenyl priopionate, isopropenyl butyrate,
isopropenyl valerate, isopropenyl caproate, isopropenyl enanthate,
isopropenyl benzoate, isopropenyl p-chlorobenzoate, isopropenyl
o-bromobenzoate, isopropenyl m-chlorobenzoate, isopropenyl toluene,
isopropenyl alpha-chloracetate and isopropenyl
alpha-bromopropionate;
Vinyl alpha-chloroacetate, vinyl alpha-bromoacetate, vinyl
alpha-chloropropionate, vinyl alpha-bromopropionate, vinyl
alpha-iodopropionate, vinyl alpha-chlorobutyrate, vinyl
alpha-chlorovalerate and vinyl alpha-bromovalerate;
Allyl chlorocarbonate, allyl formate, allyl acetate, allyl
propionate, allyl butyrate, allyl valerate, allyl caproate, diallyl
phthalate, diallyl succinate, diethylene glycol bis
(allyl-carbonate) allyl 3,5,5-trimethylhexoate, allyl benzoate,
allyl acrylate, allyl crotonate, allyl oleate, allyl chloroacetate,
allyl trichloroacetate, allyl chloropropionate, allyl
chlorovalerate, allyl lactate, allyl pyruvate, allyl aminoacetate,
allyl aminoacetate, allyl acetoacetate, allyl thioacetate,
diallyl-3,4,5,6,7,7 -hexachloro-4-endomethylene
tetrahydrophthalate, as well as methallyl ester corresponding to
the above allyl esters, as well as esters from such alkenyl
alcohols as beta-ethyl allyl alcohol, beta-propyl allyl alcohol,
1-buten-4-ol, 2-methyl-buten-1-ol-4,
2(2,2-dimethylpropyl)-1-buten-4-ol and 1-penten-4-ol;
Methyl alpha-chloroacrylate methyl alpha-bromoacrylate,
methyl-alpha-fluoroacrylate, methyl alpha-iodoacrylate, ethyl
alpha-chloroacrylate, propyl alpha-chloroacrylate, isopropyl
alpha-bromoacrylate, amyl alpha-chloroacrylate, octyl
alpha-chloroacrylate, 3,5,5-trimethylhexyl alpha-chloroacrylate,
decyl alpha-chloroacrylate, methyl alpha-cyano acrylate, ethyl
alpha-cyano acrylate, amyl alpha-cyano acrylate, amyl alpha-cyano
acrylate and decyl alpha-cyano acrylate;
Dimethyl maleate, diethyl maleate, diallyl maleate, dimethyl
fumarate, dimethallyl fumarate and diethyl glutaconate;
(4) Organic nitriles such as acrylonitrile, methacrylonitrile,
ethacrylonitrile, crotonitrile, and the like;
(5) Acid monomers such as acrylic acid, methacrylic acid, crotonic
acid, 3-butenoic acid, angelic acid, tiglic acid itaconic acid,
fumaric acid and the like; and
(6) Amides such as acrylamide, alpha-methyl acrylamide, N-phenyl
acrylamide, N-methyl-N-phenyl acrylamide, N-methyl acrylamide and
the like.
The total mols of acid constituents of the unsaturated polybasic
acid (and any saturated polybasic acid) are preferably balanced
stoichiometrically with the polyfunctional alcohol.
The heat curable composition of U.S. Pat. No. 3,215,137 (the
pertinent portions thereof which are incorporated herein by
reference) can be used in this invention.
Because of the nature of the invention, the preferred monomers are
liquid compounds soluble in the cross-linkable prepolymerized
material. This means that the cross-linkable prepolymerized
material is a homopolymer and the monomer is the same monomer from
which the cross-linkable prepolymerized material is formed, because
the liquid monomer is then most likely soluble in the
prepolymerized material and vice versa. Solvents can be used, but
very little if any solvent should be used because of the enclosed
curing (crosslinking) area used in this invention. Examples of
useful solvents and diluents are: alcohols, such as, methanol (b.p.
= 64.degree.C.), ethanol (b.p. = 78.degree.C) isopropanol (b.p. =
80.degree.C.), propanol (b.p. = 95.degree.C.), n-butyl alcohol
(b.p. = 118.degree.C.), secondary butyl alcohol (b.p. =
99.degree.C.), isobutyl alcohol (b.p. = 107.degree.C.), and methyl
isobutyl carbinol (b.p. = 131.degree.C.); glycol ethers, such as,
ethylene glycol monomethyl ether (b.p. = 125.degree.C.), ethylene
glycol monoethyl ether (b.p. = 136.degree.C.), ethylene glycol
monobutyl ether (b.p. = 171.degree.C.), diethylene glycol
monomethyl ether (b.p. = 194.degree.C.), diethylene glycol
monoethyl ether (b.p. = 195.degree.C.) and diethylene glycol
monobutyl ether (b.p. = 230.degree.C.) ketones such as acetone
(b.p. = 56.degree.C.), methyl ethyl ketone (b.p. = 79.degree.C.),
methyl isobutyl ketone (b.p. = 115.degree.C.) and isophones (b.p. =
207.degree.C); aliphatic hydrocarbons, such as hexane (b.p. =
69.degree.C.), and heptane (b.p. = 98.degree.C.), esters such as,
ethyl acetate, amyl acetate and butyl acetate; aromatic
hydrocarbons such as, benzene (b.p. = 80.degree.C), toluene (b.p. =
110.degree.C.) and mixed xylene (b.p. = 275.degree.C.); and
halogenated hydrocarbons such as, chloroform, perchloroethylene,
carbon tetrachloride (b.p. = 76.degree.C.), and trichloroethylene
(b.p. = 86.degree.C.). Water, and water plus another dilutent
(water is usually not a solvent for organic materials) can be used,
but neither is preferred. A dilutent means that the carrier is not
a solvent for the polymeric constitutents, catalyst, etc., being
used.
In general, the monomer component or components may be employed
over a relatively broad range, but usually, the amount thereof upon
a weight basis will be less than that of the prepolymerized
material. Usually, the percentage of monomer will fall within a
range of about 10 to 45 percent by weight of the total mixture of
the prepolymerized material and monomer. The preferred range of
monomer is about 20 to 40 percent in most instances.
The curing time of the systems varies between about 1 minute and
about 24 hours. This time span depends, in part, upon the type of
prepolymerized material, the monomer, the amount of catalyst, the
amount of inhibitor, and so forth. The curing temperature of the
resin systems varies, and preferably the resin system can be cured
at room temperature (15.degree. to 30.degree.C.).
The curing temperature should not be so high that the wearer cannot
keep his foot, etc., in the shoe when the rigid form of the
prosthesis is being prepared by the curing. Also the curing time
should be two hours or less for the comfort of the wearer.
As the scope of useful resin systems is extensive, the type of
promoter which can be used in those systems is also extensive. A
few exemplary promoters are given in the following paragraphs.
On of the promoter type which can be used in the resin system is a
cobalt salt which is capable of being dissolved in the resinous
composition. Suitable soluble promoters are cobalt octoate or any
other higher fatty acid salt of cobalt. The amount of cobalt salt
can be varied from about 0.001 to 0.3 percent of the salt
calculated as dissolved metallic cobalt based on the total weight
of the resin compounds, catalysts and promoter mixture employed. On
the same basis, the preferred amount of cobalt metal ranges from
about 0.05 to 0.15 percent.
The vanadium promoters disclosed in U.S. Pat. No. 3,333,021 are
useful.
Another promoter type material is a variety of aminepromoters.
Suitable amine promoters are disclosed in U.S. Pat. No. 2,480,928.
The promoters are described therein as tertiary monoamines which
contain attached to hdrocarbons, nitrogen atom two functionally
aliphatic radicals selected from the group consisting of alkyl
hydrocarbons, hydroxy-substituted alkyl hydrocarbons and aralkyl
hydroxcarbons and one aromatic radical selected from the group
consisting of aryl hydrocarbons, azo-substituted aryl hydrocarbons,
amino-substituted aryl hydrocarbons and salts thereof. Specific
examples of this class are the following: dimethylaniline,
diethylaniline, di-n-propyaniline, dimethyl-p-toluidine,
di-methyl-o-toludine, dimethyl-alpha-naphthylamine, methyl benzyl
aniline, p-dimethylaminoazobenzene, N,N-di-methyl-m-aminophenol,
p-dimethylaminophenyl oxalate, p-dimethylaminobenzaldehyde,
p-dimethylaminophenyl acetate, and p-hydroxy-N,N-di(beta
hydroxyethyl)aniline. Additionally, the promoter can be a tertiary
alkyl amine, a hydroxy alkyl amine or an acid salt thereof as a
promoter. Exemplary of these types of promoters are
diethylmethylolamine, triethylamine, triisopropylamine,
trimethylamine, triisopropanolamine, ethyl diethanolamine
hydrochloride and the like. Tertiary polyamines are also effective
for use in the instant manner, such as for example,
tetramethylbutanediamine. The amount of amine promoter useful in
the practice of this invention varies between about 0.05 to 1.0
percent based on the resin compounds, catalyst and promoter. These
amine promoters can be used in conjunction with the above cobalt
promoters.
The resin systems of this invention (containing the monomer and the
prepolymerized material) are readily cured by any conventional
catalyst. The preferred catalysts are organic peroxides most
preferably diacyl peroxides, and the preferred organic peroxides
are acetyl peroxide and benzoyl peroxide. Other useful diacyl
peroxides are caprylyl peroxide, lauroly peroxide, decanoyl
peroxide, 2,4-dichlorobenzol peroxide, p-chlorobenzoyl peroxide,
pelargonyl peroxide and propionyl peroxide. Other useful organic
peroxide catalysts include: peroxyesters, such as, tert.-butyl
peroxyacetate, tert.-butyl peroxyisobutyrate, tert-.butyl
peroxypivalate, tert.-butyl peroxybenzoate, tert.-butyl peroxy
(2-ethylhexanoate), 2,5-dimethyl-2,5-bis-(benxoylperox) hexane,
2,5-dimethylhexane-2,5-diperoctoate, and di-tert.-butyl
diperoxyphthalate; alkyl peroxides, such as, di-tert butyl
peroxide, n-butyl-4,4-bis(tert.-butylperoxy) valerate,
2,5-dimethyl-2,5-bis (tert.-butyperoxy) and 2,5-dimethyl-2,5- bis
(tert.-butylperoxy) hexyne-3; hydroperoxides, such as, tert.-butyl
hydroperoxide, a-cumyl hydroperoxide and
2,3-dimethylhexane-2,5-dihydroperoxide; and ketone peroxides, such
as methyl ethyl ketone peroxides, cyclohexane peroxides and
bis(1-hydroxyclohexyl) peroxide.
Preferably the catalyst is used in an amount small enough to get a
fast cure without excessive heat production. Usually from 0.01 to 2
percent of catalyst, based on the total weight of the resin
components, are used. Preferably about 0.1 percent of catalyst is
used.
The resin systems of this invention can also contain other
compatible additives, such as, dyes, reinforcing materials
(asbestos, chopped glass fibers), etc. The fluid polymerizable
composition can also contain compatible plasticizers, such as,
di-n-butyl styryl phosphonate and dimethyl phthalate; and
compatible fillers, such as, silicon dioxide, titanium dioxide,
calcium carbonate, silica and carbon black. The fluid polymerizable
composition can also contain a compatible conventional
inhibitor.
To add structural body to the cured polymer resins, material such
as styrene, vinyl toluene, .alpha.-methylstyrene, dimethylstyrene,
the methyl .alpha.-methylstyrenes, .alpha.-bromostyrene,
.beta.-bromostyrene, .alpha.-chlorostyrene, .beta.-chlorostyrene,
and diallyphthalate, vinyl acetate, methyl methacrylate and
divinylbenzene, can be added to the uncured polymer resins so that
they can be copolymerized with the other monomer components.
By using free-radical initiator systems such as N,N-dimethyl
aniline, sulfanilic acid, thiophenol, N,N-dimethyl p-toluidine, in
conjunction with benzoyl peroxide, for the polymerization of
acrylate esters, principally, methyl methacrylate, nearly 100
percent conversion of monomer to polymer are obtained in less than
20 minutes at temperatures of or below 120.degree.F.
Methyl methacrylate can be polymerized in the presence of
polymethyl methacrylate, using one of the above activated
initiation systems, at a temperature of or below 120.degree.F,
within a reasonable time period. Preferably there is prior
polymerization of a portion of the monomer in order to reduce the
exotherm during the polymerization. Preferably, these
polymerizations are conducted in the presence of plasticizers (e.g.
2-butoxy ethanol, carbowax) to reduce stress crazing of the solid
polymer.
Polymethyl methacrylate can be prepared in the presence of a small
amount of a cross-linking agent (e.g., ethylene dimethacrylate),
with the polymerization being continued to just below the gel
point. This polymer is then dissolved in methyl methacrylate (with
or without additional cross-linking agent) and the mixture
polymerized with the above activated initiation systems. The
incorporation of plasticizers is desirable. This is a useful
self-curing material.
In another useful self-curing scheme, copolymers of styrene and a
carboxylated monomer or copolymer, e.g., methacrylic acid and
polymethacrylic are prepared and cured polymers with polyvalant
salts curing agents to convert the polymers into tough, rigid
solids.
The self-curing resins of U.S. Pat. No. 3,215,137 can be used in
this invention.
Types of useful actinic radiation are U.V. radiation, sunlight
(visible light), etc.
In many cases, the main polymer component is prepolymerized, so
that the curable resin material placed in the prosthesis enclosure
contains a prepolymer and a cross-linkable monomer.
The ultraviolet curable resins usable in this invention include
those based on the mechanisms of photocatalysts in resinous
polymerization such as are obtained by photocatalytic initiation in
materials having ethylenic-type unsaturation. In these materials,
the initiation is of first order by double bond activation and any
terminal double bonds are progressively activated. In general, the
initiation is proportional to the concentration of monomer, and to
the square root of light intensity.
A part of the U.V. curable resin is a monomeric ethylenically
unsaturated component capable of dissolving minor amounts of a
photoinitiator which is active under ultraviolet light. The use of
a monomeric substance such as styrene alone is not practical
because of low viscosity, high shrinkage upon polymerization, etc.
For these and other reasons a higher polymeric substance such as a
compatible polyester resin is combined to form a solution, which
may be a solid or viscous liquid. The monomer preferably has
terminal double-bond unsaturation.
Suitable polymers would include almost any of the unsaturated
non-catalyzed commercial polyesters of a non-aniline type, and the
monomer co-reactant of any compatible terminal ethylenic
unsaturated monomer including vinyls, acrylics, allyls, and the
like, such as styrene, methyl methacrylate and triallyl cyanurate.
The monomer is generally used in an amount of from about 5 to 50
percent by weight of the polyester (can be a prepolymer) along with
about 0.002 to 5 percent of a photoinitiator.
An example of a useful U.V.-curable resin of the above type is a
polyester (prepared from phthalic anhydride, adipic acid, maleic
anhydride and diethylene glycol) in admixture with triallyl
cyanurate monomer, hydroquinone and azobisisobutyronitrile.
Photocurable compositions which are operable in the instant
invention are those obtained by admixing polyenes or poly-enes
containing two or more reactive unsaturated carbon to carbon bonds
located terminally, more inwardly, or pendant from the main chain
with a polythiol containing two or more thiol groups per
molecule.
As a general definition, the group of polythenes includes those
having a molecular weight as the range of 300 to 20,000 and a
viscosity ranging from 0 to 20 million centipoises at 70.degree.C.,
of the general formula: [ A -- X) wherein X is a member of the
group consisting of ##SPC1##
(The R groups do not have to be the same) and R--C.tbd.C--; is at
least 2; R is independently selected from the group consisting of
hydrogen, halogen, aryl, substituted aryl, cycloalkyl, substituted
cycloallyl, aralkyl substituted aralkyl and alkyl and substituted
allyl groups containing 1 to 16 carbon atoms and A is a polyvinyl
organic moiety free of (1) reactive carbon to carbon unsaturation
and (2) unsaturated groups in conjugation with the reactive ene or
yne groups in X. Thus A may contain cyclic groupings and minor
amounts of hetero atoms such as N, S, P, or O but contains
primarily carbon-carbon, carbon-oxygen or silicon-oxygen containing
chain linkages without any reactinve carbon to carbon
unsaturation.
A further group of polyenes which are operable in the instant
invention includes unsaturated polymers in which the double or the
triple bonds occur also within the main chain of molecules.
Examples of these include conventional elastomers derived primarily
from diene monomers, i.e., polyisoprene, polybutadiene,
styrenebutadiene rubber, isobutyleneisoprene rubber,
polychoroprene, styrene-butadiene-acrylonitrile rubber, and the
like, unsaturated polyesters, polyamides, and polyurethanes derived
from monomers containing reactive unsaturation, e.g., adipic
acid-butene diol, 1,6-hexanediamine fumaric acid, and 2,4-tolylene
diisocyanatebutenediol condensation polymers.
The polythiols useful in this invention may be simple or complex
organic compounds having at least 2 pendant or terminally
positioned --SH functional groups per average molecule. Useful
polythiols may have a viscosity range of 0 to 20 million
centipoises at 70.degree.C. as measured by a Brookfield viscometer,
and usually have molecular weights in the range of 50 to 20,000,
the preferable range being from 100 to 10,000.
A general formula for such compounds is R.sub.1 -- SH).sub.n where
n is at least 2 and R.sub.1 is a polyvalent organic moiety free
from reactive carbon to carbon unsaturation. Thus R.sub.1 may
contain cyclic groupings and minor amounts of hetero atoms such as
N, S, P, or O but primarily contains carbon-hydrogen,
carbon-oxygen, or silicon-oxygen containing chain linkages free of
any reactive carbon to carbon unsaturation.
One class of polythiols which is particularly useful in connection
with this invention because essentially odorless cured polyether
"casts" results, are the esters of thiol-containing acids of the
general formula HS -- R.sub.2 -- COOH where R.sub.2 is an organic
moiety containing no "reactive" carbon to carbon unsaturation with
polyhydroxy compounds of the general structure R.sub.3 -- OH) n
where R is an organic moiety containing no "reactive carbon to
carbon unsaturation" and n is 2 or greater. These compositions will
react under suitable conditions to give a polythiol having the
general structure R.sub.4 -- OC -- R.sub.5 -- SH).sub. n where
R.sub.4 and R.sub.5 are organic moieties containing "no reactive"
carbon to carbon unsaturation and n is 2 or greater.
In suitable compositions, the total combined functionally of (a)
the unsaturated carbon to carbon to bonds per molecule in the
polyene and (b) the thiol groups per molecule in the polythiol is
greater than 4.
Other ultraviolet curable systems suitable for use in the practice
of this invention include, for example, the iodoformsensitized
hardenable colloids disclosed in U.S. Pat. No. 1,587,274, and the
metal carbonyl-sensitized aliphatic dieneunsaturated long chain oil
systems described in U.S. Pat. No. 1,891,203, The pertinent
portions of the disclosures of these patents are incorporated
herein by reference. Many other ultraviolet curable polymers
systems are known and are suitable for use in this invention.
The photocurable compositions have to be kept in the absence of
actinic radiation, e.g., in light-impermeable packs or canisters.
Many of the photocurable compositions can be stored for weeks or
months under such conditions.
Any light with high enough energy per quanium or of short enough
wavelength can initiate polymerization directly. For practical
reasons concerned with readily available energy sources, and to
provide quick polymerization after the invention prosthesis has
been placed on the body member, it is desirable to use a
photochemical initiator which acts as an absorbent and releases
free radicals from ultraviolet light in the region of 3600
Angstroms. Convenient spectral sources containing bands of 3600
Angstrom light energy are mercury vapor discharge lamps, sunlamps,
fluorescent lamps with special phosphors and sunlight. Typically,
the irradiation is done with source about 12 inches from the
prosthesis enclosure. Irradiation is typically done for 5 to 30
minutes.
No specific range of times for exposures to actinic radiation
needed to achieve curing can be given, for every cast possesses
substantial differences in thickness, etc. The exposure to actinic
radiation should continue until substantially all of the resin has
been converted to a solid substance in the case of casts, or until
the material has become sufficiently rigid so that the patient's
foot may be removed from the prothesis device and then final curing
accomplished thermally. (This is necessary because the area
available for exposure to u.v. is limited in the case of the foot
prothesis and the depth of penetration by u.v. light is also
limited.) As an example, the prosthesis resin may be cured under
the light flux of an Ascorlux pulses xenon lamp placed 30 inches
from the surface of the cast. Substantial gellation will take place
under these conditions through resin coats (polyene-polythiol) of
0.030 of an inch thick with 2 minutes of exposure; thicker casts
require longer times of exposure. In all exposures to actinic
radiation it is necessary to protect the skin of the patient from
burn and damage. This is easily done by covering the patient with
sheets or blankets impenetrable to actinic radiation.
The prosthesis enclosure, into which the actinic radiation-curable
material is placed, must be actinic radiation-penetrable at least
over a portion of its surface. This usually means the use of a
transparent or translucent material, e.g., a transparent
polyethylene. A colored transparent surface can be used if a more
attractive prosthesis is desired. When U.V. is used, it is
preferable to use an actinic radiation-impenetrable material next
to the skin in order to avoid skin burns, etc. All normal safety
precautions should be used when conducting an actinic radiation
cure.
The ultrasonic energy-curable systems of this invention can be any
curable resin system which is curable, using ultrasonics, at or
around room temperature up to about 100.degree.F. Suitable resin
systems include many of the unsaturated commercial polyesters of a
nonaniline type, and the monomer correactant of any compatible
terminal ethylenic unsaturated monomer including vinyls, acrylics,
allyls, and the like, such as styrene, methyl methacrylate and
trially cyanurate. The monomer is generally used in an amount which
is very low is relation to the weight of the polyester.
The ultrasonic curing is achieved by exposure for a short time on
the order of from a few seconds to one-half hour to ultrasonic
energy. The ultrasonic energy is typically supplied by an
ultrasonic transducer.
The compositions to be cured, i.e., to be converted into the solid
mass of the prosthesis may include materials to increase the
rigidity of the prosthesis or resin extruders such as wood flour,
talc, etc. Heavier materials which are frequently used as fillers
or loaders in resinous compounds, e.g., Barytes, are operative but
are useful only if the weight of the prosthesis is of no
importance.
The systems of this invention can be stored for long times, either
separately or mixed (provided in the latter instance a catalysted
mixture must be heated or exposed to actinic radiation or
ultrasonic vibrations to initiate the curing to any significant
degree).
The surface of any prosthesis can be covered with a soft flexible
material which makes it soft and comfortable to the skin, but such
a coating material must not be of such a thickness as to consist of
a cushion or like arrangement or else the rigidity feature of the
invention prosthesis will be defeated, for example, the top of a
foot prosthesis may be covered with a very thin layer of leather or
simulated leather. The surface of the prosthesis not contacting the
skin may be adhered, for example, by gluing, to the cast or shoe to
insure that the prosthesis remains securely in the desired portion
in relationship to the cast or footwear and the body part.
A package to be purchased by the shoe wearer could contain one
prosthesis for each foot, the injection devices and material to be
injected, and detailed instructions for the mechanism to be
utilized in the injection of the thermoplastic fluid into the
hollow interior of the prosthesis. The actual injection of the
materials into the cavity of the arch support could be done as a
skilled service by the trained footwear salesman or could be done
by the purchaser of the articles of footwear. First aid kits or
hospital kits could be similarly packaged and sold for use when
casts are applied.
One (1.0) mole percent is 0.01 mole per 100 grams of resin. Weight
percent or percent by weight as used throughout this application,
unless otherwise specifically stated, is defined conventionally as
grams per 100 grams of resin.
The following example illustrates this invention. All percentages
and parts therein are by weight, unless otherwise stated.
EXAMPLE
A foot was placed in a shoe as shown in FIG. 1, the prosthesis
enclosure 16 being made of aluminum. Poly(methyl methacrylate) was
dissolved in monomeric methyl methacrylate in a ratio of 1:1 by
weight. The solution was then admixed with 0.1 percent by weight,
based on that composition, of acetyl peroxide an initiator, and 0.1
percent by weight, based on that composition, as a polymerization
promoter. The catalyzed solution was injected into the enclosed
area by means of line 36. Line 36 was removed. The catalyzed
solution rapidly polymerized at 120.degree.F. and was allowed to
self cure to a rigid prosthesis for the metatarsal arch of the
foot. A leather covering was placed between the prosthesis and the
foot.
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