| No
12,908 |
 |
A.D.
1909 |
Date
of Application, 1st June, 1909 - Accepted, 26th May,1910
COMPLETE
SPECIFICATION.
Process of Producing
Colloidal Sols or Gels.
I, THEODOR SVEDBERG, of Upsala, in the
Kingdom of Sweden, Doctor of Philosophy, Fellow of the University of
Upsala, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
This invention relates to a process of
producing colloidal sols or gels.
Some methods of producing colloidal sols
or gels from organic substances are before known. Some of the said
processes, for instance those described in the British Patents No.
25,735 of 1906 and No. 14,681 of 1905, are based on the reaction of
large quantities of alkali on the substances to be converted into a.
colloidal state, whereby on account of the mere chemical action of the
strong alkali, the substances which are finally brought into the
colloidal solution cannot be said to be chemically identical with the
substances originally treated.
A process has also been suggested for
producing colloidal solution in which a crystalloidal solution of the
substance to be treated is gradually added and thoroughly mixed with a
boiling mixture of soap, starch and water so that the solvent
volatilizes. In this process starch may be replaced by cereals or other
colloids and soap may be replaced by aqueous solutions of alkalies,
alkali earths, borax and fats, resins, varnishes, oils, waxes, balsams,
paraffins, or saponine solutions and the like.
All the processes hereinbefore referred
to are thus based on the employment, besides the substance to be
dissolved, the solvent of the crystalloidal solution, and the
dispersion means, of an auxiliary means, such as alkali, soap, or a
colloid, for instance starch.
On the other hand, it is also before
known that dilute liquid sols may be obtained from certain substances,
such as mastic and some other resins, by dripping the ethyl-alcoholic
solutions of the said substances into water. By such a procedure, it
is, however, only in few cases possible to obtain colloids and even in
such cases only in an imperfect and unstable form.
The object of the invention is to
provide a general method of producing liquid or solid colloidal sols or
gels.
The invention consists, chiefly, in
heating a crystalloidal solution of the substance to be
converted into
the colloidal state, bringing the heated solution into a likewise
heated quantity of a dispersion means (external phase), removing the
solvent in any suitable manner, for instance by boiling, and reducing
the obtained sol by evaporation to the concentration required. If
desired, a protecting colloid may thereupon be added, according to
known principles, or the liquid sol may be converted by evaporation of
the imbibition liquid, into a dry sol, or, by adding an electrolyte,
into a gel. It is to be noted that the substances to be brought into a
colloidal state all the time maintain their molecular structure.
The solvent may consist of any suitable
matter in which the substance
to be converted into a colloidal state is soluble as a crystalloid and
which is, moreover, wholly or partially mixable with the dispersion
means (external phase). As a. dispersion means a simple liquid or a
mixture of simple liquids not previously containing any colloids may be
used in which the substance to be converted into a colloidal state is
insoluble as a crystalloid. Thus, for instance, if wax is the substance
to be converted into a colloidal state, and water is the dispersion
means, I may use ethyl alcohol as a. solvent. If caoutchouc is the
substance to be converted into a colloidal state and
ethyl alcohol is the dispersion means, the solvent may be, for
instance, benzol.
The process may be carried out in the
following manner:
The substance to be converted into the
colloidal state is dissolved as
a crystalloid in a suitable solvent, which may consist of a single
chemical compound or of a mixture of such compounds (two or more),
whereupon the solution is heated to a temperature dependent in each
case on the physical-chemical properties (such as melting points,
boiling points etc.) of the said substance as well as on those of the
solvent and the dispersion means employed. The dispersion means by
which the disperse phase (internal phase) is to be permanently or
temporarily obtained, is heated to a suitable temperature dependent on
the factors herein before set forth. The crystalloidal solution is
thereupon brought into the dispersion means. This operation should in
some cases, for instance when colloids of a small size of the particles
are desired, be carried out so slowly that the quantity of the solvent
brought into the dispersion means may be kept, for instance by
continued or periodical boiling or evaporation, below such a limit that
the mixed liquid obtained is not able in a considerable degree to
dissolve as a crystalloid in the disperse phase (internal phase). The
solvent is finally removed from the liquid sol obtained so that the
latter obtains the purity which in each case is considered necessary
whereupon the sol is reduced by evaporation to a suitable concentration.
Thus, if a colloidal solution of wax in
water is desired, a more or
less saturated alcoholic solution of the said substance is first
produced in usual manner, said solution being kept as near the boiling
point of the alcohol as possible, whereupon the alcoholic solution is
gradually added to the water, which is, preferably, kept boiling, In
adding the alcoholic solution to the boiling water it is to be observed
that the percentage of alcohol in the water is always kept below a
certain limit. When the water solution has obtained the desired wax
concentration, the supply of alcohol is shut off, whereas the boiling
is continued until the solution is quite free from alcohol, even a very
small quantity of alcohol acting to diminish the durability of this
colloidal solution.
By adding an electrolyte the colloidal
sols obtained by this process
may be converted into the corresponding gels. In some cases it is
desirable to increase the stability of the sols obtained which is
performed by adding protecting colloids. If such an addition, for
instance of gum, has been made and the liquid sol has been reduced to
dryness by evaporation, a solid sol is obtained which may again be
dissolved in usual manner in a suitable dispersion means.
Having now particularly described and
ascertained the nature of my said
invention and in what manner the same is to be performed, I declare
that what I claim is:—
The process of producing liquid or solid
colloidal sols or gels, while
maintaining the molecular structure of the substances to be converted
into colloidal state, characterised in that a crystalloidal solution of
the substance to be converted into the colloidal state is heated and
then brought in its heated condition into a heated dispersion means
which does not previously contain any colloid, the solvent being
thereupon removed in known manner, for instance by boiling, and the sol
obtained reduced by evaporation to the concentration required.
Dated the
18th day of May, 1909.
W. P. THOMPSON & Co.,
285, High Holborn, London, W.C., and at
Liverpool and Bradford,
Patent Agents for the Applicant.
Redhill: Printed for His Majesty’s Stationery Office, by Love
& Malcomson, Ltd. — 1910
Similar patents were also filed on the same day 1 June 1909, in
Switzerland (No.49141) Verfahren zur Überführung von
Körpern in den kolloiden Zustand
Austria (No.45193) Verfahren zur Herstellung von kolloidalen
Lösungen.
Denmark (No.12767) Fremgangsmaade til Fremstilling af kolloidale Soler
eller Geler.