Improvements in Adhesive Compounds.
Year: 1898

page_text: Date of Application, 24th May, 1898-Accepted, 2nd July, 1898
Improvements in Adhesive Compounds.
A communication from CHARLES MICHAEL HIGGINS, Manufacturer, of the City
of New York, United States of America.N
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, 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 that class of compounds consisting of dextrine com-
bined with a boron compound and water, such as shown in British Patent
No. 22682 of December 29th, 1891. This present invention consists mainly in
a special method or process for combining the boron compound with the dextrine
solution, whereby certain results or advantages are secured as hereinafter set
forth. In my correspondents former patent the boron compound is combined
with the dextrine solution preferably at a high or hot temperature, and an excess
of alkali is preferably afterwards added. This. present process provides a method
whereby the boron compound may be combined with the dextrine at a low
temperature, or cold, and good results thereby obtained and without an excess
of alkali, enabling the product to be made neutral or nearly so, with certain
characteristic advantages for certain purposes. To this end is first dissolved the
dextrine in a dilute solution of caustic alkali preferably cold, and then add to
the alkaline dextrine solution boracic acid, sufficient to make an adhesive com-
pound with the dextrine and at the same time neutralise the alkali or nearly so.
This invention therefore consists mainly in the feature above outlined as herein-
after fully set forth and claimed.
The improved process is adapted to produce either a mucilage or paste,
according to the proportions of the ingredients and the quality of the dextrine
used.
I will first give the preferred practical working formula for a good liquid
mucilage on the improved system.
In one gallon of water dissolve sufficient caustic soda or other alkali to make a
dilute solution, having a decided alkaline reaction, say a density of about 1% to
2 degrees Baume. This will be obtained by adding about 3 3, fluid ounces of
lye of 40 degrees Baume to one gallon of pure water. In this dilute alkaline
solution dissolve 7 to 7 ½ pounds of yellow dextrine. The dextrine will dissolve
in this solvent with the aid of stirring or agitation and without the necessity of
heat. When all dissolved, add 6 or 7 ounces of boracic acid and mix thoroughly
with the alkaline dextrine until the said acid is fully dissolved and combined.
The boracic acid will immediately neutralize the alkali so as to prevent any
furthering darkening action on the dextrine, and it will form an adhesive com-
pound with the dextrine with the effect to greatly increase its adhesiveness,
forming a very smooth solution of light colour and of limpid consistency, yet
great density and without any strong alkalinity or causticity. After the boracic

page_text: acid has been added and fully dissolved and combined as described, the mucilage
is complete and may be bottled for sale.
The advantage of this system is that the alkali enables the dextrine to be
dissolved readily at a low temperature without the application of heat, and while
the alkali would tend to make the dextrine solution very dark and limpid if
allowed to act long thereon, this is prevented by the immediate addition of the
boracic acid which overcomes the thinning and darkening effect of the alkali and
which thus neutralizes or more than neutralizes the alkali, forming a very
adhesive and smooth solution which will not be corrosive or caustic to anything
on which it may be used, and which will have a permanent light amber colour
and which will also have a certain characteristic quality of consistency and
adhesiveness especially suited for certain particular purposes.
Of course, if it is desired to give the mucilage a decided alkaline reaction, more
of the caustic alkali may be used relatively to the boracic acid, or if it is desired
to give the mucilage an acid reaction less of the alkali and more of the acid may
be used, as will be readily understood, but it is generally preferred to so propor-
tion the ingredients that the finished composition will be nearly neutral or slightly
beyond neutrality on the alkaline side, but preferably much less alkaline than
borax. This is one of the great advantages of the described process or system,
for by this described means of avoiding an excess of free alkali, or strong alkaline
reaction, the solution is prevented from darkening by age which always occurs
when a dextrine solution is made with free alkali or even with a decided alkaline
reaction such as occurs even with a solution having the same degree of alkalinity
as borax.
Instead of using a dilute caustic alkali, such as soda, ammonia or potash, a
dilute solution of an alkaline salt, preferably carbonate or bicarbonate of soda,
may be used, the dextrine being dissolved and the boracic acid afterwards added
as described with substantially the same effect.
The proportions of the several ingredients given may vary considerably,
according to the consistency desired, and my correspondent does not limit himself
to any fixed proportions, but the amount of the boron compound will generally
regulate the other ingredients, and it is desirable that this exist in rather a large
percentage relatively to the dextrine, that is, from about 3 to 6 or 7 per cent.
of the weight of the dextrine, more or less, the alkali being preferably always
about such as will produce nearly a neutral result, and the water varying according.
to the viscosity or consistency desired.
In order to increase the viscosity of the described mucilage, it is preferred to
add thereto about 1 to 5 per cent. (by volume) of alcohol, either methyl or ethyl
which will have the effect to partly coagulate or thicken the solution and also
acts as a powerful preservative and makes the mucilage dry more rapidly when
applied.
If desired, the dextrine may first be dissolved in hot or boiling water and then
allowed to cool, and when cool the alkali may be added and dissolved and the
boracic acid may then be added as before. This will make a little clearer and
lighter solution, as the alkali will need to be only a very short time in contact
with the dextrine, and this modification will secure all the other advantages
described with little if any corresponding disadvantage. Of course the alkali may
be added to the solution of dextrine when hot, if desired, or when the whole
mixture is made cold as at first described, heat may then be finally applied after.
the boracic acid is added. But while these variations will not depart from the
essential features of this invention, yet one of the main advantages lies in the
ability to dispense with heat altogether, as already set forth, which will be duly
appreciated.
The temperature at which it is preferred to make the cold alkaline solution
of the dextrine is between 60 degrees F. and blood heat, as very little darkening
action of the alkali on the dextrine will occur within this range, whereas a high
temperature or prolonged heat would make a very dark and watery solution. If

page_text: desired however the solution may be made at a very much lower temperature by
the application of cold or refrigeration to the solution, which will still further
reduce the darkening effect, while the solvent effect of the alkali is still active
at low temperatures.
The preferred formula for the dextrine pasté according to the present system
is as follows;-
To one gallon of cold water add 3 ounces of caustic soda of 40 degrees Baume.
Then add from 5 to 6 pounds of white dextrine and stir thoroughly till all
dissolved. When dissolved, add 5 to 6 ounces of boracic acid slightly moistened
or made into a paste with water or other excipient, then incorporate this acid
thoroughly with the dextrine until fully dissolved and combined therewith.
This will produce a white semi-fluid pasty mass, very smooth spreading under
the brush and very adhesive and having a nearly neutral or slightly alkaline
reaction. A suitable flavouring or antiseptic substance may be then added and
the finished paste may now be run into jars or other receptacles and sealed in
the same ready for sale.
Of course, the variations before described in reference to the mucilage will
apply to the paste formula also, as will be understood.
In some cases the dextrine may be first dissolved directly in pure cold water
and the alkali then added after the dextrine is fully dissolved to be followed by
the addition of the boracic acid as already described. This variation will be
particularly desirable where white dextrine is employed, but may also be used
with yellow dextrine.
.
In making the mucilage after the addition of the boracic acid and before the
bottling, the mucilage may be left to stand and settle for sometime or it may
be strained or filtered before bottling up, if preferred.
It is generally preferred to add the boracic acid to the alkaline solution of
dextrine as soon as the dextrine is fully dissolved in the alkali, or as soon as the
alkali is fully combined with the dextrine, or a few minutes thereafter, as this
will generally, make a lighter solution, but in some cases the alkali may be
allowed to act upon the dextrine for some prolonged time before the boracic
acid is added, as this will produce a smooth and more adhesive and tenacious
quality of the finished product, although it may be a little darker in colour but
not objectionably so.
Instead of adding the boracic acid in a dry moistened or pasty state to the
dextrine solution, it can of course be first dissolved in hot water or alcohol and
then added to the dextrine solution.
The gallon referred to in the formulas here given is the American gallon of
128 ounces.
Having now particularly described and ascertained the nature of the said
invention as communicated to me by my foreign correspondent and in what
manner the same is to be performed I declare that what I claim is:
-
1. The described process of making an adhesive compound viz. dissolving or
combining dextrine with an alkaline solvent and then adding boracic acid until
neutrality is nearly or actually reached or exceeded, substantially as herein set
forth.
2. The described process of making an adhesive compound viz. dissolving dex-
trine in a cold alkaline solution and then adding boracic acid until neutrality
is nearly or actually reached or exceeded substantially as herein set forth."
3. A dextrine paste or mucilage formed by the combination with a dilute
caustic alkali and with dextrine dissolved therein, of boracic acid added thereto
till neutrality is nearly or actually reached or exceeded substantially as set forth.
4. A dextrine paste or mucilage formed by the combination with solvent water
and dextrine dissolved therein, of the ingredients of borax combined therewith
in proportion of about five or more per cent. of the weight of the dextrine and
having the acid and alkali in such proportions that some of the boracic acid

page_text: remains in excess, giving an alkalinity to the compound less then borax, substan-
tially as and for the purpose set forth.
5. A dextrine paste or mucilage formed by the combination with a dilute
alkali and dextrine dissolved therein, with boracic acid added thereto in such.
proportions as to give an alkaline reaction less than borax substantially as herein
set forth.