Year: 1886

page_text: I, JEROME BONAPARTE MELVIN, of Lowell, Massachusetts, United States of
America, Chemist, 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 the treatment of resins or resinous substances for the
purpose of producing compounds thereof which will possess a greater degree of
hardness, and consequently a higher melting or fusing point, than is the case with
such resins or resinous substances when in their natural or normal condition; and
the chief object of the said invention is to obtain at a small expense, resinous
compounds possessing all or most of the qualities to be found in, and therefore
capable of being employed in lieu of, certain gums and other substances which are
procurable only at a relatively high cost.
My invention is chiefly designed to provide a comparatively cheap substance or
material which will effectually take the place of copal and other resins or resinous
substances in the manufacture of varnishes of various kinds, but it will be obvious
to any person having a knowledge of the subject to which the said invention
relates that the compounds I produce may be used for various analogous or other
purposes.
In carrying my invention into practice I prefer to employ that descrption of.
resin which is ordinarily known in commerce as "rosin," and of this material I take
any desirable quantity and place the same in an ordinary melting kettle or vessel
which may be either open or closed. I heat the rosin to a sufficiently high
temperature to melt the same, and at a time when the mass has reached a somewhat
thick consistency (which will be at about 230° Fahrenheit) I introduce a certain
proportion (hereinafter indicated) of oxide of zinc in the condition of powder,
I stir the whole together by means of a rod or any other convenient article in
order that the rosin and the oxide may be intimately combined. This stirring
should preferably continue until the operation is terminated. When the oxide has
been added, the temperature should be gradually increased till the chemical
reaction commences which will occur when the mass has reached a temperature of
about 360° Fahrenheit, and which will be apparent by reason of the bubbles of gas
rising to the surface. This temperature should be maintained for a few minutes,
that is to say, until the mass has become thick and nearly, or quite, hard. No

page_text: further treatment is absolutely essential as the compound is, at this stage, ready
for use in the manufacture of varnishes or for any other purpose to which it is
applicable; but as the mass presents at this time a somewhat spongy and uneven
appearance I prefer to continue the operation by raising the temperature to a
sufficient degree (vizt to about 400° Fahrenheit if the proportion of oxide be small
and to a correspondingly higher degree if the proportion of oxide be larger) and to
maintain this temperature until the compound has become thoroughly fluid. It
will then. be smooth and, even, and' will be, when it has become cold and hard, in a
more advantageous condition for sale, than would be the case if this latter melting
operation were not effected. It is, however, desirable to say that, as at these high
temperatures rosin is highly inflaminable, care must be taken to prevent the ignition
thereof.
The proportion of oxide of zinc as compared with the rosin, must be varied
according to the degree of hardness which it is desired that the compound shall
possess, it being borne in mind that the larger the proportion of the said oxide the
harder the compound will be. The following proportions I have found
advantageous in the production of resinous compounds capable of being used in
lieu of comparatively expensive resins or gums for the manufacture of varnish viz,
for every 100 (one hundred) parts by weight of rosin either 2 (two and one
half), 5 (five), 7 (seven and one half), 10 (ten), 15 (fifteen) or 25 (twenty five)
parts by weight of oxide of zinc. It will be readily understood that other
proportions may be employed according to the result desired, that is to say, more
or less hardness, and a higher or lower melting point in the compound.
Although I have indicated in the above description one oxide only viz:-oxide
of zinc, I desire it to be understood that I may employ in lieu thereof, oxide of
lead, of iron or of manganese. If iron is. used I prefer the sesqui-oxide, and if
manganese is used I prefer the black oxide. And it is desirable to say that when
either of these last named oxides is used in practising my invention, the resulting
compound will be of a black, or very dark, colour and consequently will not be
suitable for use in the manufacture of light coloured varnishes.
I desire it to be understood that, although I prefer to employ the article known
in commerce as "rosin" other resinous substances may be used with advantage such
as balsams and resinous gums; and as my object is to treat substances which can
be obtained at a small cost in such a manner as to bring them into a condition to
be capable of employment in place of more expensive products, the kind of resinous
materials which may be used in lieu of rosin will be readily understood by all
persons conversant with the subject.
It will be obvious that the compounds made according to my invention may be
advantageously used in combination with coal and otlier tar, wax and similar
products to obtain compounds useful for many purposes.
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 manufacture of resinous compounds by treating rosin or other resinous
substances with oxide of zinc, or other metallic oxides, substantially as, and for the
purposes, above set forth.