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Патент USA US2116910

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I06. UUMPUSI HUNS,
Examiner
COATING 0R7 ‘PLASTIC.
85
.5 C
Patented May 10, 1938
2,116,910
UNITED STATES PATENT OFFICE
2,116,910
PLASTER FOR THE PRODUCTION OF SURGI
CAL CASTS
Jean Piccard, Swarthmore, Pa.
No Drawing. Application April 30, 1935,
Serial No. 19,026
16 Claims. (Cl. 106-24)
ple, in orthopedic surgery and especially in the
with this invention may comprise an anhydrous
mixture of a basic compound containing no ele
ments having an atomic weight greater than that
of phosphorus, as, for example, the oxides hy
5 treatment of bone fractures.
As is well known, it has for many years been
‘Thai,
a uminum, ma mm
This invention relates to plaster and more spe
ci?cally to plaster for use in the production of
surgical casts, such as are employed, for exam
customary, after a fracture has been set, to im
mobilize the affected parts, where possible, by
enveloping them in a plaster cast. Ordinarily
10 this cast has been prepared from plaster of Paris,
usually by rolling a layer of powdered plaster of
Paris into a gauze bandage, wetting the roll,
and then unrolling and rerolling the bandage
around the fractured part.
15
droxides or carbonates of lithium, sodium, B‘é'r 1- 5
or acid salt likewise contai'ning no such heavy
element, as, for example; organic acids, as ben
zoic, salicylic, oxalic acids, etc., or salts 0 am
monia or an a
a 1 me a
h an inorganic acid, 10
as phosphoric acid, etc., as diammonium hydro
gen phosphate, ammonium H15 arc en
Hos-_
"'Wor other water soluble phosphates, e'tc.
Upon the addition of small amounts of water
'
It is very desirable to obtain information as to
to such mixtures a neutralization reaction-15.3715
ing to the formation of a salt takes place, and
the crystallization of this salt sets the plaster
the position of the bone ends soon after the cast
has been applied, and also as to the condition
of the fracture at intervals during the healing
process. To accomplish this purpose it is usual
0 practice to take X-ray photographs of the frac
tioigg?eéefalunma-setting
.is-.dependent
upon t, 8 par cular?ingredients chosen, andthese
ture, necessarily through the plaster cast. Since,
willprefverably be selected to obtain the desired
however, plaster of Paris possesses only a very
limited permeability for X-rays, the photographs
obtained by such procedure lack detail and clar
sira e to use more weakly basic materials, such
as the oxides, hydroxides or carbonates of mag
Now in accordance with this invention thereis
provided a plaster suitable for the production of
surgical casts which possesses a marked *rm?
to X-ra s and accordingly permi s
The
ma
sp_e%ii’g_f'jetting. Thus, in general it will be de
nesium and aluminum, and relatively weak, or
s- ity and are far from satisfactory.
abilit
to a, hard, rigid mass.
e
30 fair-mg of clear §-ray photographs through casts '
ganic acids in order to obtain a plaster which
made therefrom. The casts produced in accord
(U. ST P., heavy powder) wilf set'Tnuch more
ance with this invention are also superior to those
heretofore produced in that they are compara
rapidly than onureparedilrnglarly withJh?-t
tively light in weight and can be worn with greater
3;, comfort and less inconvenience.
The plaster in accordance with this invention
will comprise essentially a mixture of two or
more chemicals, preferably in an anhydrous form,
altho water of crystallization may in some in
40 stances be present, which will, in the presence
of water, undergo a chemical reaction leading
to the formation of a new compound or salt
which, under the conditions present, will crys
_ tallize into a mass of interwoven crystals thus
4" forming a hard rigid plaster. This mixture of
compounds will be further characterized in ac
cordance with this invention by the fact that it
contains substantially no materials containing
an element having an atomic weight greater than
that of phosphorus. This will insure a satisfac
'
does not set too quickly. Even the physical con
dition of the ingredients may have a noticeable
effect on the speed of setting. Thus, for exam
ple, a plaster prepared with magnesium oxide‘ 30
formgilgiggg§i~
mag'?esite”.
_“
_
.
T?'s'féadTf using a, basic and an acidic mate- 35
rial in the production of the plaster in accord
ance with this invention, a salt of a weak acid
with a metal having an atomic weight not greater
than that of phosphorus, as, for example, mag
nesium acetate, aluminum acetate, etc., and 40
an acidic material of the type described above or
another salt, as, for example, ammonium oxalate,
etc. may be used. The reaction of setting in such
cases will be double decomposition rather than
neutralization.
45
The various ingredients of the plaster in ac
cordance with this invention will preferably be
?nely powdered and intimately mixed together
to insure even and thorough reaction when wet.
They will of course be protected fromatmospheric'
tory permeability to X-rays in the plaster casts moisture until used.
The following examples are illustrative of plas
produced therefrom as well as comparatively~
light weight.
55
Thus, for example, the plaster in accordance
ters suitable forpractical use in accordance with
this invention:
'
65
2
2,110,910
pared in absence of moisture and kept in L.
Example I
Four parts by weight of very ?nely powdered
‘aluminum h droxide and seven parts by weight
of powdered salicylic acid are intimately mixed
' together. The y pow er will keep inde?nitely
and when moistened with water will slowly
harden to a rigid plaster very transparent to
X—rays.
10
Exam le II
p
One part of powdered ma nesium oxide, of
the type known as “dead Burnt magnesi'te" is
mixed with about three parts of powdered ben
zoic acid. Casts made with this plaster will
“more rapidly than casts made with the
plasters described above.
Example III
A valuable plaster in accordance with this
20 invention comprises salicylic acid and magnesium
oxide. Plaster casts made from
harden still faster than the ones
and the casts are remarkably
strong. Depending on the ratio
these materials
described above
light and very
of salicylic acid
25 and magnesium oxide used a neutral or a basic
saiicylate can be produced when the plaster sets.
A preferred way of making this plaster consists
in mixing two parts of salicylic acid with about
one part of "dead burn magnesi e.
30 speed of reac ion can
e pro uce
A greater
if part or all
of the magnesite is replaced by the more active
magnesium oxide, U. S. P., heavy powder.
Example IV
86
u
ve par s o
ammonium
Qigdrogen phosphate. When this powder 1's
in xe
w
wa er
w reaction sets in and a
foamy paste is produced with the liberation of
40 carbon dioxide. The paste will ?nally harden to
a solid porous mass which becomes very hard and
is considerably lighter than water. If this
plaster is used for a plastercast a very light cast
will be obtained which, however, is not quite as
45 transparent to X-rays as the preceding ones.
Example V
An excellent plaster may be made by mixing
?nely powdered diammonium h dro en
hos
hate with magnesium oxide. if made was
magn slum oYiHe U. S. P., this plaster sets rather
ra i
and if prepared with dead burnt mag
ne te 1 sets too slowl to be convenient. For
his reason the use 0
55
1’ magnesium on e
a mixture of both kinds
5 pre erre .
y
5 s
e prepare
mm the plasters in
accordance with this invention by any known
and usual method for their production. How- 5
ever, because of the solubility of certain of the
ingredients it is not advisable to immerse the
plaster in water to moisten it, but rather the
desired amount of water or only a slight excess
should be added to the dry plaster.
10
It will be understood that the details and ex
amples hereinabove set forth are illustrative
only, and not in any way in limitation of the
invention as herein described and claimed.
It will be further understood that the plaster 15
in accordance with this invention may be ad
vantageously used for other purposes than in the
production of surgical casts, and the description
hereinabove with reference to such use is illus
trative only.
20
What I claim and desire to protect by Letters
Patent is:
1. A plaster of the character described com
prising a substantially dry mixture including an
organic acid and a compound selected from the 25
group consisting of magnesium carbonate and
the oxides and hydroxides of aluminum and
magnesium, said mixture being capable of hard
ening to a rigid mass through chemical reaction
between the ingredients when moistened with 30
water and being characterized by the fact that
it is substantially free from any compound con
taining an element having an atomic weight
greater than that of phosphorus.
Four parts of magnesium carbonate (U. S. P.)
are mixed with a
c'losedvesse?is inde?nitely stable.
aryin
e we
e speed of reaction
can be regulated so as to obtain a plaster desir
able !or the speci?c purpose for which it is
needed. When water is added to this mixture a
w complicated chemical reaction takes place dur
ing which ammonia is set free and insoluble
magnesium ammonium phosphate is formed. If,
as is the case for surgical use, the formation of
much free ammonia is objectionable, its libera
65 tion can be reduced to a permissible minimum
by addition of a weak acid, as, for example,
boric acid.
While here again a wide variety of ratios of
ingredients may be used, a preferred product is
70 obtained by intimately mixing ten parts of ?nely
powdered diammonium hydrogen phosphate with
about two parts of magnesium oxide U. S. P.
heavy powder, one part powdered dead burnt
magnesite and three parts powdered boric acid.
,, mepmewe
.
2. A plaster of the character described com- 35
prising a substantially dry mixture including sali
cylic acid and a compound selected from the
group consisting of magnesium carbonate and
the oxides and hydroxides of aluminum and
magnesium, said mixture being capable of hard
ening to a rigid mass through chemical reaction
between the ingredients when moistened with
water and being characterized by the fact that
it is substantially free from any compound con
taining an element having an atomic weight
greater than that of phosphorus.
3. A plaster of the character described com
prising a substantially dry mixture including a
water soluble phosphate and a compound se
lected from the group consisting of magnesium
carbonate and the oxides and hydroxides of 60
aluminum and magnesium. said mixture being
capable of hardening to a rigid mass through
chemical reaction between the ingredients when
moistened with water and being characterized
by the fact that it is substantially free from 55
any compound containing an element having
an atomic weight greater than that of phos
phorus.
‘
4. A plaster of the character described com- 60
prising a substantially dry mixture including an
ammonium phosphate and a compound selected
from the group consisting of magnesium car
bonate and the oxides and hydroxides of alumi
num and magnesium, said mixture being capable 65
of hardening to a rigid mass through chemical
reaction between the ingredients when moistened
with water and being characterized by the fact
that it is substantially free from any compound
containing an element having an atomic weight 70
greater than that of phosphorus.
5. A plaster of the character described com~
prising a substantially dry mixture including
ammonium dihydrogen phosphate and a com
pound selected Irom; the group consisting of 75
IVUI
(EMT-ING 0mm.
85
2,116,910
magnesium carbonate and the oxides and hy
droxides of aluminum and magnesium, said mix
ture being capable of hardening to a rigid mass
through chemical reaction between the ingredi
ents when moistened with water and being char
acterized by the fact that it is substantially free
from any compound containing an element having
an atomic weight greater than that of phosphorus.
6. A plaster of the character described com
10 prising a substantially dry mixture including
diammonium hydrogen phosphate and a com
pound selected from the group consisting of
magnesium carbonate and the oxides and hy
droxides of aluminum and magnesium, said mix
15 ture being capable of hardening to a rigid mass
through chemical reaction between the ingredi
ents when moistened with water and being char
acterized by the fact that it is substantially free
from any compound containing an element hav
20 ing an atomic weight greater than that of phos
phorus.
7. A plaster of the character described com
prising a substantially dry mixture including an
acidic compound and a compound selected from
25 the group consisting of the oxides, hydroxides
and carbonates of magnesium, said mixture being
capable of hardening to a rigid mass through
chemical reaction between the ingredients when
moistened with water and being characterized
30 by the fact that it is substantially free from any
compound containing an element having an
atomic weight greater than that of phosphorus.
8. A plaster of the character described com
prising a substantially dry mixture including an
35 ammonium phosphate, a compound selected from
the group consisting of magnesium carbonate
and the oxides and hydroxides of aluminum and
magnesium, and a weak acid, said mixture
being capable oi’ hardening to a rigid mass
through chemical reaction between the in
gredients when moistened with water and
being characterized by the fact that it is sub
stantially free from any compound con
taining an element having an atomic weight
greater than that of phosphorus.
9. A plaster of the character described com
prising a substantially dry mixture including an
ammonium phosphate, a compound selected from
the group consisting of magnesium carbonate and
the oxides and hydroxides oi.’ aluminum and mag
nesium, and boric acid, said mixture being capable
of hardening to a rigid mass .through chemical
reaction between the ingredients when moistened
with water and being characterized by the fact
that it is substantially free from any compound
containing an element having an atomic weight
greater than that oi‘ phosphorus.
10. A plaster of the character described com
prising a substantially dry mixture including
salicylic acid and a compound selected from the
group consisting of the oxides, hydroxides and
carbonates of magnesium, said mixture being
capable of hardening to a rigid mass through
chemical reaction between the ingredients when
3
'
moistened with water and being characterized
by the fact that it is substantially free from any
compound containing an element having an
atomic weight greater than that of phosphorus.
11. A plaster of the character described com
prising a substantially dry mixture including am
monium dihydrogen phosphate and a compound
selected from the group consisting of the oxides. ,
hydroxides and carbonates of magnesium, said
mixture being capable of hardening to a rigid 10
mass through chemical reaction between the in-
gredients when moistened with water and being
characterized by the fact that it is substantially
free from any compound containing an element
having an atomic weight greater than that of 15
phosphorus.
12. A plaster of the character described com
prising a substantially dry mixture including di
ammonium hydrogen phosphate and a compound
selected from the group consisting of the oxides, 20
hydroxides and carbonates of magnesium, said
mixture being capable of hardening to a rigid
mass through chemical reaction between the in
gredients when moistened with water and being
characterized by the fact that it is substantially 25
free from any compound containing an element
having an atomic weight greater than that of
phosphorus.
13. A plaster of the character described com
prising a substantially dry mixture including 30
salicylic acid and magnesium oxide, said mixture
being capable of hardening to a rigid mass
through chemical reaction between the ingre
dients when moistened with water and being char
acterized by the fact that it is substantially free 35
from any compound containing an element hav
ing an atomic weight greater than that of phos
phorus.
14. A plaster of the character described com
prising a substantially dry mixture including di
ammonium hydrogen phosphate and magnesium
oxide, said mixture being capable of hardening to
a rigid mass through chemical reaction between
the ingredients when moistened with water and
being characterized by the fact that it is sub
stantially free from any compound containing an
element having an atomic weight greater than
that of phosphorus.
'
15. A plaster of the character described com
prising a substantially dry mixture including di
ammonium hydrogen phosphate, magnesium ox
ide, and boric acid, said mixture being capable '
of hardening to a rigid mass through chemical
reaction between the ingredients when moistened
with water and being characterized by the fact 55
that it is substantially free from any compound
containing an element having an atomic weight
greater than that of phosphorus.
16. A plaster of the character described com
prising a substantially dry mixture consisting of 60
about 19% magnesium oxide, about 62% diam
monium hydrogen phosphate and about 19%
boric acid.
.
JEAN PICCARD.
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