Processing of dicalcium phosphate and sodium montmorillonite

A process for forming a dispersion of dicalcium phosphate in montmorillonite clay comprising mixing sodium montmorillonite with dicalcium phosphate and some water, and subjecting the mixture to dry heat.

BACKGROUND OF THE INVENTION 
This invention relates to a method of processing dicalcium phosphate and 
sodium montmorillonite and more particularly to a method for the changing 
of sodium montmorillonite to a phosphated montmorillonite in order to 
produce a thoroughly dispersed stabilized calcium montmorillonite with the 
crystals of dicalcium phosphate becoming finely subdivided without the 
application of mechanical grinding action. 
The present invention is concerned with hydrated dicalcium phosphate widely 
available commercially in substantially pure form. Dicalcium phosphate has 
long been known to be well suited as a polishing agent especially for 
relatively soft surfaces. It finds application in use as such a polishing 
agent for dentifrices, silver polishes, lacquer and furniture rubbing 
compounds and the like. It has also been widely used as a food supplement 
and in many preparations thereof is used in suspended form in a liquid 
vehicle so that fine particle size is essential to prevent settling and to 
maintain a stable suspension to maintain its original state of dispersion. 
One problem in using dicalcium phosphate is that it is difficult to create 
the sufficiently fine particle size necessary for its potential uses and 
which fine particles hasten any process in which the dicalcium phosphate 
is to be consumed or utilized from a suspension thereof. Dicalcium 
phosphate has in some cases been provided so that it completely or 
substantially passes through a standard 325 mesh sieve. The maximum 
dimensions of the opening of such a sieve are 44.times.44 microns which is 
large compared with the desired particle size of 1-3 microns. While it 
might be possible to reduce the size of this material by specialized 
grinding methods such as micronizing or steam jet milling or the like, 
this is an expensive and troublesome expedient and in any case it does not 
appear to have been resorted to by any commercial manufacturer of 
dicalcium phosphate. 
My U.S. Pat. No. 2,943,982, issued July 5, 1960 discloses a process for 
simultaneously comminuting and forming a suspension of dicalcium 
phosphate. In accordance with the process disclosed in that patent, there 
is formed a suspension of pulverized dicalcium phosphate in water which 
also contains suspended therein a swelling clay of the montmorillonite 
group. The suspension is then rapidly brought to a temperature of 
200.degree. F. or higher and maintained at such a temperature for a short 
time, whereupon the preparation is cooled or allowed to cool for 
subsequent uses. 
In many cases, however, it is not desirable to use dicalcium phosphate in 
an aqueous suspension, and a dispersed solid phase of the substance is 
preferable. 
SUMMARY 
It is therefore an object of this invention to produce a dispersed stable 
solid phase of dicalcium phosphate and montmorillonite clay. 
Another object of the present invention is to provide a new method for the 
comminution of dicalcium phosphate. 
Yet another object of the present invention is to provide a method for the 
reduction in particle size of dicalcium phosphate by a process utilizing 
sodium montmorillonite clay to form a stable suspension thereof but 
without affecting the basic physiochemical properties of the negatively 
charged montmorillonite platelets. 
A still further object of the present invention is to provide a suspension 
of finely divided dicalcium phosphate in the micron particle size range 
free of any tendency for crystal growth. 
A further object is to produce a thoroughly dispersed stabilized calcium 
montmorillonite simultaneously having the dicalcium phosphate formed in 
small particle size being interacted and dispersed therewith a minimum of 
mechanical treatment. 
When dicalcium phosphate is processed, as disclosed herein with a sodium 
montmorillonite clay, it has been found to create an extremely effective 
and useful shaving lotion. It also is an excellent product for polishing 
and cleaning dentures, and can be utilized as a highly dispersed oil soap 
ideal for cleansing and lubricating the body. The substance produced by 
the present invention can further be utilized for the liquid dispersion of 
various minerals, for example, calcium, magnesium, iron, manganese, etc. 
for medicinal purposes and can also be used to improve the stability and 
dispersion of lotions and ointments. 
Other objects of the invention will appear as the description thereof 
proceeds.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In accordance with the invention, there is formed a dispersion of dicalcium 
phosphate and sodium montmorillonite clay by first mixing the sodium 
montmorillonite clay with a hydrated dicalcium phosphate and some water. 
Thereafter the mixture is heated until it no longer contains any moisture. 
The invention resulted from my experimentation with the process described 
in my U.S. Pat. No. 2,943,982 discussed above. In the course of my 
experimentation I found that the environment under which the co-suspension 
of dicalcium phosphate and sodium montmorillonite exists when exposed to 
heat need not be moist to produce results comparable to those obtained 
with my prior invention. Thus, contrary to the invention disclosed in that 
patent, the process of this invention need utilize only very little water, 
and also contrary to the invention disclosed in that patent, the liquid 
phase of the products suspended is not maintained throughout the process. 
Thus the mixture is subjected to heat until all moisture in the mixture 
has been eliminated. 
I have found that as long as there is present initially water in the 
concentration of 2.73% by weight, the process will be operable. The heat 
is preferably dry heat at a temperature of 300.degree. F. Microwave 
radiation can also be utilized. This temperature is generally maintained 
until all moisture has been eliminated. 
The proportions of the ingredients are not critical. Virtually any 
proportions of sodium montmorillonite and dicalcium phosphate can be used. 
Although any ratio of these two products will permit the process to be 
operable, I have found that a ratio of about 2 parts sodium 
montmorillonite and 1.5 parts calcium phosphate is highly satisfactory. As 
stated above, so long as sufficient water is present to maintain an 
initial concentration of at least 2.73%, virtually any amount of water 
will permit the process to be operable, although obviously additional heat 
input would be necessary to eliminate extra water to the extent that more 
than the necessary concentration is present at the initial subjection of 
the mixture to heat. Preferably the water used is distilled or deionized 
water. 
The resultant product may then be utilized in dry powder form in oils, 
paints, and mineral suspensions. Should it be desired to create a liquid 
dispersion of the solid phase obtained from the invention as thus far 
disclosed, the product resulting from this process can thereupon be mixed 
into a slurry or liquid, for example, by adding distilled demineralized 
water under rapid agitation. It has been noted that the solubility of the 
solid phase is increased and that when converted to a liquid phase, the PH 
is significantly lowered to the vicinity of 4.4 to 4.6. The liquid phase 
is additionally highly calcium saturated at about 90% with 10% sodium, and 
there is increased phosphorous in solution being approximately six times 
that of the calcium in solution. 
Accordingly, while the invention has been described with particular 
reference to specific embodiments thereof, it will be understood that it 
may be embodied in a variety of forms diverse from those shown and 
described without departing from the spirit and scope of the invention as 
defined by the following claims.