Paraffin compositions having improved heat reservoir

A paraffin composition that is solid at 25.degree. C. and has an improved heat reservoir by virtue of being combined with inert solid material, wherein the paraffin composition contains from 25 to 55% by weight of at least two constituents comprising aluminium or one of its oxides or silicates, and magnesium or one of its oxides or silicates.

The present invention relates to paraffin compositions having improved 
thermal properties. 
For many centuries, paraffins have been known and used on account of their 
thermal properties. Extracted initially from certain shales, they were 
first utilised for their relatively low melting point and their long 
solidification level or plateau, in order either to maintain a constant 
temperature or to transmit heat while maintaining such temperatures. 
The use of paraffins in water-baths, as candles, protective layers on the 
surfaces of preserved foods, and as thermal lagging, are just some 
examples of various long established uses. 
Paraffins are generally chemically classed as saturated hydrocarbons. Those 
having low melting points and even low vaporisation points are well-known 
as fuels (methane, propane and butane in particular); ascending the 
homologous series, paraffins that are liquid at normal temperature (oils), 
and then paraffins that are solid at normal temperature (paraffin), are 
first reached. For example, n-docosane (C.sub.22 H.sub.46) melts at 
44.4.degree. C. at atmospheric pressure, and n-tetracosane (C.sub.24 
H.sub.50) at 50.9.degree. C. A fairly extended melting point range can be 
obtained by choosing a suitable paraffin. 
Furthermore, mixtures of paraffins very often have fusion and thus 
solidification plateaux that are relatively stable, so that it is possible 
to find a mixture that is suitable for any desired temperature within a 
desired range of applications. 
It is know that when a molten product is cooled, the temperature stabilises 
throughout the duration of the solidification if the product is pure, 
though this temperature may vary if the product consists of a mixture. 
In fact, this plateau is long and constant for a pure paraffin and is 
generally slightly "sloping" for a mixture, namely less than 5.degree. C. 
and more often less than 3.degree. C. between the start and end of 
solidification for mixtures of paraffins having molecular weights of the 
same order of magnitude. 
The duration of this temperature plateau is due to the large latent heat of 
fusion which, combined with a relatively low coefficient of heat 
transmission, is utilised in candles. Taking the above two examples, the 
latent heat of fusion of n-docosane is 37.6 cal/g, and for n-tetracosane 
is 38.7 cal/g. 
Hereinafter, only paraffins or mixtures of paraffins that are solid at 
ordinary temperatures, that is to say having a melting point above 
approximately 25.degree. C., will be considered. 
However, although the paraffins have a high heat reservoir on account of 
the amount of heat liberated on solidification, their coefficient of heat 
transmission is relatively low, as mentioned above, which is generally an 
advantage. 
Numerous applications involve the concept of "transmission time," by 
distinguishing on the one hand the case where only the transmission of 
heat from an external source and the temperature plateau play a role (a 
water-bath for example), and on the other hand the case where the paraffin 
is allowed to cool while liberating its heat of solidification without the 
simultaneous involvement of an external heat source. 
In the latter case the question of time is involved, and depending on 
whether a slow or rapid liberation of heat is desired a greater or lesser 
thermal conductivity is necessary. It has been suggested, for example in 
the field of thermal lagging intended for maintaining a body at a certain 
temperature, to include a certain volcanic muds in the mixtures of 
paraffins, that will increase the coefficient of heat transmission. 
However, the use of these natural products has three major disadvantages, 
namely the high price due to the problem of supply, variations in their 
properties that are incompatible with the desired degree of constancy, 
often essential in numerous practical applications, and a water retention 
that can be eliminated only above 100.degree. C., all these factors 
representing major disadvantages both for the products themselves and for 
the stability of the paraffins and their mixtures. 
The present invention provides a paraffin composition that is solid at 
25.degree. C. and has an improved heat reservoir by virture of being 
combined with inert solid material, wherein the paraffin composition 
contains from 25 to 55% by weight of at least two constituents comprising 
aluminium or one of its oxides or silicates, and magnesium or one of its 
oxides or silicates. 
Thus in order to obviate the disadvantages of the prior art, the present 
invention provides paraffin compositions having an improved heat reservoir 
and a more easily controlled coefficient of thermal conductivity by adding 
commonly used products having very stable properties and which are 
moreover anhydrous, thereby providing various industrial and economic 
advantages. 
Moreover, the choice of suitable composition ensures low prices and a high 
degree of constancy in the properties, while providing a thereby increased 
heat reservoir. In addition, by varying certain factors the coefficient of 
heat transmission and thus the time of the solidification plateau may be 
regulated. 
Under these conditions, if a source of external heat is employed, the thus 
improved paraffins maintain a very constant temperature while supplying, 
by transmission, the heat necessary for the desired heating effect, the 
transmission being regulated depending on the requirements; if on the 
other hand the heat reservoirs of the paraffins are utilized without using 
an external source, the heat flux per unit time and consequently the 
duration of the temperature plateau may be regulated by choosing an 
appropriate thermal conductivity. In the following description and for the 
sake of simplicity, the discussion will be restricted to cases where 
paraffins are employed without an external heat source during use. 
It will also be noted that the temperature plateau during solidification 
increase in duration with the latent heat, and decreases when the 
coefficient of heat transmission increases. 
Moreover, it is clear that the inclusion in the paraffins of chemically 
inert substances that are solid at the temperatures in question influences 
the heat reservoir of the whole system, but does not alter that of the 
paraffins contained in the mixture. It is thus convenient to distinguish 
between the heat reservoirs per unit mass or volume of the whole mixture, 
and the heat reservoirs per unit mass or volume of the constituents, and 
in particular of the paraffins, considered individually. 
It will be seen that the present invention enables this heat reservoir of 
the mixtures to be increased very considerably with respect to that of the 
prior art. 
For the sake of simplicity and by convention, only the heat reservoir 
corresponding to the temperature plateau, that is to say the heat emitted 
between the start and end of solidification, will be considered. 
In this way, even when considering a mixture of paraffins having a slightly 
sloping plateau, between two very close end-of range temperatures, the 
cooling corresponding to inert substances may be practically ignored with 
respect to the heat reservoir of the paraffins, as is shown by experience 
(see the following table). 
The total heat reservoir in practice thus amounts to that of the paraffins 
and is generally proportional to the amount of paraffins in the mixture 
and the latent heat of the paraffins. 
In the following description, for the sake of simplicity and by convention, 
the total volume heat reservoir (RCVT) will denote the amount of heat 
liberated during solidification of the paraffins per unit volume of the 
mixture, expressed in Kcal/m.sup.3. 
If C.sub.o is the latent heat of fusion of a paraffin per unit mass, 
.rho..sub.o its mass per unit volume, and V.sub.o the amount in volume per 
unit volume of this paraffin in the total mixture, then the corresponding 
volume heat reservoir is C.sub.o .rho..sub.o V.sub.o. 
If the mixture contains several paraffins the total volume heat reservoir 
may thus be considered as substantially equal to the sum of the volume 
heat reservoirs corresponding to each component paraffin. In fact, this 
sum is found in experience to differ little from that of the mixture of 
paraffins and inert products. 
The present invention perferably relates to paraffins having thermal 
properties that have been improved by incorporating finely divided metals, 
in particular metals of the second and third groups of Mendeleev's 
periodic table, their oxides, or their silicates; very good thermal 
properties have been obtained with amounts by weight of 45 to 75% of 
paraffins in the total mixture, i.e. with amounts of 25 and 55% of metals 
or their compounds. 
The best results have been obtained with amounts by weight of metals and 
metal compounds of from 30 to 50%, in particular with the light metals of 
the aforementioned groups, and their compounds. 
Moreover, if it is desired to utilise these mixtures of paraffins to 
provide thermal lagging or "casings" for therapeutic purposes, the thermal 
conductivity of the mixture is the basic parameter that has a decisive 
influence on the heat flow and, consequently, the therapeutic effect. 
The paraffin compositions as defined above have in particular the property 
that they possess a greatly improved heat reservoir and a thermal 
conductivity that may be selected within a broad range. 
The present invention also relates to the therapeutic applications of the 
paraffin compositions defined above and thermal lagging or casings 
comprising the previously described paraffin compositions, but whose 
conductivity and plasticity are determined as a function of their 
therapeutic application. 
In particular, these thermal casings are solid at 40.degree. C., more 
preferably at 50.degree. C., and comprise 45 to 65% by weight of paraffins 
and 35 to 55% by weight of fillers comprising metals, their oxides and 
their silicates. 
The paraffins that can be used may be suitably mixtures of n-docosane and 
n-tetracosane, in amounts respectively of 75 to 85% and 15 to 25%, more 
preferably 80 to 85% and 15 to 20% by weight. 
Moreover, the fillers may comprise a first category of constituents that 
improve the thermal conductivity of the compositions, such as magnesia, 
aluminium or alumina, in proportions that may be from 5 to 10%, more 
preferably from 7 to 9%, by weight. 
They may also comprise a second category of constituents that improve the 
plasticity of the compositions, such as kaolin, magnesia or talc, in 
proportions that may be from 8 to 15%, more preferably from 10 to 12%, by 
weight. 
The invention will be further described with reference to the following 
illustrative examples. In particular, reference will be made to the 
following table showing the mass composition and total volume heat 
reservoir of mixtures formulated by way of example and numbered 1 to 14. 
In all these examples, a paraffin mixture of n-docosane and n-tetracosane 
in volumetric proportions of 18:82 was used, having a plateau at other 
temperatures; for other applications, other paraffins would be chosen as a 
function of their melting points. 
The inert substances were added hot in a divided state, with stirring so as 
to produce a uniform distribution of the inert particles in the mass of 
paraffins. 
In the following examples magnesia, alumina and emery, which is in practice 
an alumina, were used as oxides, and these various oxides were both 
anhydrous and pulverulent. Aluminium powder (19 or 22 AFNOR) or aluminium 
granules was used as metal. Powdered kaolin, that is to say basically 
aluminium silicates containing some metal oxides, was also used. 
The total volume heat reservoirs obtained with these examples ranged from 
22.8 to 28.6 Kcal/dm.sup.3, which illustrates the improvement that has 
been achieved. 
Furthermore, a conductivity range of 0.32 to 0.48 Kcal/h/m/.degree.C. was 
observed, whereas the values of known commercial products are 
approximately 0.45 to 0.55. 
TABLE 
__________________________________________________________________________ 
COMPOSITIONS GIVEN IN PERCENT BY WEIGHT 
EXAMPLES 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 
__________________________________________________________________________ 
AFFINS 
65.4 
65.4 
67.0 
70.9 
67.2 
61.6 
65.7 
47.2 
47.2 
54.4 
53.0 
53.0 
46.4 
44.1 
MgO 9.4 
9.4 
9.7 
10.2 
9.7 
8.2 
8.7 
6.8 
6.8 
7.8 
3.5 
3.5 
A1.sub.2 O.sub.3 
25.2 23.3 46.0 46.4 
Emery 25.2 23.1 
30.2 46.0 37.6 44.1 
Aluminium 
19 AFNOR 37.8 
22 AFNOR 18.9 25.6 37.6 
Kaolin 5.9 
5.9 
7.2 
11.8 
Coefficient of 
thermal 
conductivity 
0.32 
0.32 
0.32 
0.35 
0.35 
0.34 
0.37 
0.47 
0.41 
0.47 
0.38 
0.46 
0.48 
0.42 
Kcal/h/m/.degree.C. 
Total volume 
heat reservoir 
28.6 
28.6 
27.7 
27.3 
27.3 
26.6 
26.6 
25.5 
25.5 
25.5 
25.0 
23.8 
23.6 
22.8 
Kcal/dm.sup.3 
__________________________________________________________________________ 
From the table it will be seen that the most remarkable results are 
obtained with amounts by weight of 3 to 11% of magnesia and 23 to 46% of 
alumina or 18 to 38% of aluminium; in fact, the combination of 2 to 15% of 
magnesia and 15 to 50% of aluminium or alumina with 45 to 75% of paraffins 
in practice constitutes an economical and thermally effective range with 
stable properties. 
These combinations have the considerable advantage of exhibiting, in the 
same volume, a heat reservoir that is improved to an extent of as much as 
40%, with a much greater conductivity range, thereby enabling the 
utilisation time to be prolonged. 
As regards the therapeutic applications, examples of thermal casings and 
their utilisation will now be described, the examples being chosen from a 
whole series of clinical observations. 
In general, the treatments were carried out using the compositions of 
examples 10, 11 and 12 described above, the compositions having a high 
thermal conductivity, good plasticity, a melting point of approximately 
50.degree. C., and appropriate total volume heat reservoir. 
The thermal casings according to the invention are used in the normal 
manner by melting sufficiently slowly a mass of the paraffin composition 
and spreading the latter over a plastic or non woven sheet to form a layer 
approximately 2 cm thick. The mass is allowed to cool until a skin of 
appearance slightly more mat than that of the mass is formed, and is then 
applied by surrounding the part to be treated with a thin non woven cloth 
or preferably a sheet of metallised polyester and varnish, so as to 
prevent heat losses. 
Four main areas of clinical conditions have been treated by means of the 
casings according to the invention, namely functional re-education 
(heating and muscular relaxation for active re-education with recovery of 
joint mobility, for trauma sequelae, or for vasodilatory action 
applications), in rheaumatology (muscular rheumatoid conditions, 
arthrosis, or polyarthritis), in dermatology (dermatoses, Rynaud's 
illness, or sclerodermia), and in gastro-enterology (pain syndromes, 
colopathies, or periviscerites) or as an adjuvant in the treatment of 
obesity and its syndromes. 
In general, the clinical indications for the use of the casings according 
to the invention are those requiring an excellent localised and profound 
hyperaemia. 
Of the clinical tests that have been carried out on the therapeutic 
activity of the casings according to the invention, a sample of case 
histories is given below.

FIRST EXAMPLE: Functional re-education 
A fall suffered by a male aged 45 produced a serious trauma in the right 
knee. X-ray examination did not show any bone lesion. The condition was 
diagnosed as hydarthrosis, which was initially treated by ultrasound and 
then by administration of prednisone, but without any marked improvement. 
The patient complained of serious pain that progressively got worse. There 
was no restriction in bending movements or abnormal movements, but the 
pain occurred on walking, at the level of the joint interspacing. 
Radiography showed femoral condyles with blurred outlines, which were 
treated with radiotherapy without any noticeable results. 
Casings according to the invention were then applied. After five 
applications the pain diminished but walking was still laboured. After ten 
further applications, knee flexion became normal, extension was complete, 
and walking had improved. The treatment was then considered to be 
complete. 
SECOND EXAMPLE: Rheumatology 
A woman aged 55 presented a scapulo-humeral periarthrosis with nocturnal 
cramp exacerbated by lifting movements of the arm. Radiography did not 
show any bone lesion. A severe limitation in abduction movements and 
particularly in retropulsion, which was very painful, was observed, as 
well as intense pain also at the level of humeral head. A low-frequency 
treatment did not give any results. 
A series of five applications of the casings according to the invention 
followed by massage was prescribed, and a remarkable improvement was 
found. After a dozen further applications and massage, retropulsion is no 
longer painful and the condition is considered cured. 
THIRD EXAMPLE: Dermatology 
A man aged 50 has suffered for five years from a dry palmarplantar 
psoriasis, which was painful and exhibited chapping and has been treated 
for 3 years by conventional methods without any marked result. 
Casings according to the invention were then applied every other day and a 
significant improvement was found in the hands after a fortnight, and in 
the feet after one month. A complete cure was obtained after 3 months, but 
the applications were continued for a further month to avoid any 
recurrence of the symptoms. 
FOURTH EXAMPLE: Gastro-enterology 
A man aged 60 suffered from trouble caused by adhesion following a 
penetrating wound of the central abdominal wall produced by a bull. Since 
the accident and after an operation the patient occasionally suffered from 
severe trouble due to the adhesions, accompanied by a strong feeling of 
nausea. 
The patient was treated with a circular abdominal casing according to the 
invention for 40 minutes three times a week in order to obtain a humeral 
reversal and a congestion of the abdominal space. An improvement was 
obtained from the second casing, and the cure was complete after six 
treatments. 
Furthermore, treatment with localised casings cured cases of gastritis and 
gastro-intestinal ulcers. 
Finally, casings according to the invention have been used as adjuvants in 
slimming cures, by applying dorsal, circular pelvic and scapula casings to 
both sides for an average time of 45 minutes, for subjects having a normal 
circulation. The weight loss results obtained are at least double those 
obtained with hot water-bath treatments for 45 minutes. 
It should be noted that the casings according to the invention do not have 
any harmful or toxic effect when applied locally, and they may easily be 
sterilised by raising the temperature to a value below the decomposition 
temperature of the paraffins, and thus by heating at temperatures of at 
least 140.degree. C., but they are contra-indicated in conventional cases 
of contra-indication of heat casings, that is to say particularly in cases 
of circulatory disorder, thrombophlebitis or serious difficulties in 
sensitisation or sensitiveness. 
Of course, the compositions according to the invention may be used 
prepacked or in combination with one or more active substances or 
excipients compatible with cutaneous application.