Improvements in or relating to Adhesive Compounds
Year: 1898

page_text: Improvements in or relating to Adhesive Compounds
A communication from CHARLES MICHAEL HIGGINS, Manufacturer, of 168-170,
Eighth Street, Brooklyn, New York, United States of America.
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:-
The present invention relates in part to that class of paste or adhesive compounds
set forth in Boult (Higgins) British Patents of June 6, 1896, No. 12,447 and of
April 9, 1897, No. 9108, which are made by digesting or partly digesting starch
in a digesting fluid and arresting the digestion at a certain point. The present
improvement lies in the special nature of the digesting agent used, in its mode of
final combination with the starch, and in the special combination of ingredients
and the special process employed, as hereinafter fully set forth.
It has been heretofore well known that most acids will digest or liquefy starch
when the starch is boiled or heated in a dilute solution of the acid, but my corre
spondent has discovered that solutions of certain salts, particularly salts of alumina,
and more especially sulphate of alumina will readily digest starch with some
important advantages over acids, and this forms one feature of this invention.
Another novel feature of this invention is that after the starch has been dissolved
in the digesting salt of alumina, an alkali or an alkaline salt is added to decom-
pose the digesting salt and thus produce a soft flocculent or gelatinous precipitate
of alumina which becomes diffused through and combined with the starch and.
adds important qualities to the resulting paste, as hereinafter shown. My corre-
spondent prefers to use borax and an alkali, added successively, to neutralize the
alumina salt and produce the gelatinous deposit or hydrate, but either the borax
or alkali may be used alone. My correspondent does not limit himself to starch in
this system, as any other neutral adhesive substance may be used; by neutral, any
substance is meant which has no decomposing reaction on the salt of alumina
itself, or rather that does not combine chemically with the alumina but leaves
it free in the form of a soft precipitate or gelatinous hydrate, such as flour, starches
and other carbo-hydrates and adhesives. Neither does my correspondent limit
himself to salts of alumina, as equivalent materials such as salts of zinc and other
substances or metals may be used, which will give gelatinous or soft flocculent
precipitates on decomposition, always preferably using those salts which have a
strong digesting action and which usually have a strong acid reaction, whose pre-
cipitates are white and have more or less of an adhesive or gelatinous nature, the
best type of this class being the simple salts of alumina. This invention there-
fore consists mainly in the features above outlined, as hereinafter fully set forth
and claimed.
In describing the practical working of the invention, I will first give an actual
working formula of one embodiment of this invention, which may be taken as a
model formula showing the principle and operation of the invention and also the
preferred practical method for producing a superior adhesive paste for ordinary
General use.

page_text: Take one pound of sulphate of alumina, preferably finely ground or powdered,
and add this to two pounds of powdered starch and mix the two intimately. Then
stir this mixture into one gallon of water, heated in a jacketed kettle to a tempera-
ture below the jellifying point of the starch, say from 150° to 170° F. This will
make a milky fluid which should be kept constantly stirred while heat is applied
to gradually raise the temperature of the mixture. The sulphate of alumina will
immediately dissolve in the water and commence to digest the starch, which latter
will first jellify and then digest in the solution as the heat is continued. When
the mixture acquires a temperature of about 185° F. it will form a soft gelatinous
paste which will gradually become softer and finally liquefy, losing its gelatinous
nature entirely, or almost entirely, as the temperature rises. The sulphate of
alumina in solution in such a large proportion thus actually converts or digests
the starch, acting the same as a digesting acid but with special advantage, as will
appear later. The digestion may be arrested at any stage desired, while the starch
is yet gelatinous or after it has become fully liquefied by stopping or arresting the
heat, or by adding a neutralizing alkali or alkaline salt, according to the con-
sistency or character of the paste desired to be produced. In this preferred formula,
it is assumed that the digestion will be carried so far as to fully liquefy the starch,
producing a running or nearly running opalescent liquid which will appear at
about a temperature of 195° F. to 205° F., and within about forty to sixty
minutes after the starch has been added. When this stage is reached, one and
one half (1) pounds of borax is added mixed with about half (½½) a gallon of
water, making a milky gruel, and now this "borax gruel is poured very slowly
and gradually into the solution of digested starch, stirring constantly. The borax
will at once dissolve and arrest further digestion by neutralizing the sulphate of
alumina and thereby decomposing the sulphate at the same time, it will produce a
soft precipitate of gelatinous hydrate of alumina which will become evenly diffused
all through the mass of digested starch, producing a smooth homogeneous paste
of a beautiful alabaster white color of good body and of semi-fluid consistency.
The heat is continued during the addition of the borax, at which time the tempera-
ture will fall, but is allowed to again rise until the borax is fully dissolved and the
deposit of the gelatinous hydrate is formed as described, which will take but a few
minutes, during which the temperature is usually allowed to rise to about 175°
to 185° F., when the heat is shut off. The reaction of the mixture will still be
slightly acid notwithstanding the large proportion of borax added, the acidity
probably being due to the sulphate of soda formed in the reaction and to some
boracic acid set free in the mutual decomposition of the sulphate of alumina and
the borax. In most cases, it is preferred to add at this point, five fluid ounces of
caustic soda lye of 40° B. or the same quantity of aqua ammonia 20° which will
increase the viscosity and the adhesiveness of the paste and also act as an anti-
septic, and this will give the paste a slightly alkaline reaction which is more
desirable. This addition of the caustic alkali, however, while a great improve-
ment is not essential. At this stage any flavouring substance or aromatic anti-
septic may be added and the paste will then be finished and may be run off into
receptacles or packages and allowed to cool when it will become somewhat thicker,
assuming a soft, pasty semi-fluid or non-flowing consistency, and it is then ready
for use.
The paste thus produced will have the following qualities:-It will contain
about 73 per cent. of water and about 27 per cent. of solid matter, the gelatinous
alumina forming a very large part of the bulk, fully one third (1/3) or one half (2)
that of the digested starch. The paste will be extremely soft, homogeneous and
smooth, of a brilliant and unchanging white color with an alabaster tint, and it
will spread under the brush with great ease into a smooth unctuous film, not showing
any gelatinous granulation like the ordinary starch or flour paste. The element
of the digested starch in this paste possesses in itself a most positive and active
adhesiveness, while the soft gelatinous hydrate of alumina diffused all through
the starchy mass also possesses a decided adhesiveness, but of a more inert, mild or

page_text: 23
passive kind, which makes a most desirable combination with the positive
adhesiveness of the starch and it has the effect of giving to the very
adhesive but more fluent starch a much greater "body or substance and an
extraordinary quick glue-like "catch," or immediate stickiness notwithstanding
the very large percentage of water held by the paste. This property of the
gelatinous hydrate of alumina also prevents the paste striking through to any
extent, as it seems to stop or fill the pores of the paper or other surface to which it
is applied, thus acting as a filling which stops penetration, and as it has great
affinity for the hydrating water it thus holds it tenaciously and prevents too rapid
drying which would be objectionable for many purposes, so that this paste possesses
in a remarkable degree not only great body for its great amount of moisture, but
also a quick and tenacious glue-like adhesiveness when spread, with great cement-
ing power when finally dried.
For paper hanging this paste is admirably adapted, as it spreads very smoothly
and easily, sticks immediately, yet dries slowly, and thus gives ample time for
manipulation and does not strike into paper or wall. It is also specially good for
labeling on either absorbent or non-absorbent surfaces such as wood, glass or metal,
and will even stick labels on bright tin most securely, which is a very critical
work. For the latter purpose it would appear that the gelatinous metallic oxide
or hydrate all through the paste seems to get a chemical adhesion with the metallic
surface, which ensures the adhesion of the pasted label, and in the case of the
absorbent wood, the filling property of the gelatinous hydrate before referred to,
prevents the striking in of the paste into fibres or pores, so that on such different
surfaces as tin and wood the paste is able to stick at once and adhere permanently,
which are most important qualities adapting this paste for general use in the
various trades and manufactures.
It will thus be seen that by the present method of manufacture, the digesting
element of the paste is made also to serve as a contributory adhesive element of
great value, and as this element is very cheap and of an innocuous mineral nature
and employed in a large percentage, it greatly reduces the cost of manufacture and
renders the paste proof to the rapid change and decay to which ordinary starch or
flour pastes are subject.
It will be noted that the mixture of the powdered starch and sulphate of alumina
or other digesting salt together, forms, per se, a new paste making compound, in
dry or powdered form which will produce an improved adhesive paste by simply
dissolving the said mixture or powder in hot or boiling water until the starch is
digested. The product of this action will be an improved paste, practical and fit
for immediate use without addition of any other ingredient. When, however, the
precipitating element or alkaline substance is added to this product, a still greater
effect is obtained, and the paste may then be diluted with, about fifty per cent.
more water and yet have as much or more body and fully as great if not greater
adhesiveness with a slower drying quality as before described, which is very valu
able for work requiring much manipulation or delay after pasting.
In
Instead of using borax, or borax and an alkali, as the precipitating agent, an
equivalent amount of caustic alkali or other precipitant may be used alone.
the formula given, about eleven (11) fluid ounces of lye at 40° B. would be such
equivalent.
The proportions of neutralizing or decomposing alkali here given correspond to
the specified quantity of commercial sulphate of alumina, which is very acid, but
where purer or less acid sulphate is used correspondingly less alkali will be neces-
sary for its neutralization or decomposition as will be readily understood.
Any quality of sulphate of alumina may be used from neutral or nearly neutral
to strongly acid, but for fine pastes, a pure commercial quality is preferred which
is not very acid.
Of course, it is not necessary always to mix the starch and sulphate together dry,
as the sulphate may be dissolved in the water and the starch then added, or a
solution of the sulphate may be added to a solution of the starch, as will be under-
stood, but the order first named will be preferred in many cases.

page_text: Neither is it necessary in all cases to continue the digestion of the starch in the
sulphate solution till actually liquefied or converted. The action may be stopped
at merely the "starch-paste or gelatinous" stage and the precipitating element
then added, but in this case a much less proportion of starch will be required to
produce a paste of the same consistency, which at the same time will be much
weaker and less adhesive, as will be readily appreciated. It may be here generally
stated that more or less than
to the gallon
two pounds of starch
of water
Where the digestion
as in the model formula may be used.
is not carried far less may be used, and where it is carried so far as to render the
starch very fluent more than two pounds up to say four, six or more pounds to
the gallon can be used, as is described in Boult (Higgins) former British Patent
of June 6, 1896 on which the process herein described is an improvement.
Starch of any kind may be used in this process and flour of any of the cereals
may be substituted for the starch with no essential difference in result. Besides
flour or starches, other carbo-hydrates and adhesive substances, vegetable or animal,
may be used, such substances having little or no decomposing action on the solu-
tion of sulphate of alumina when dissolved therein or added thereto. It is desirable
or important however that the adhesive substances dissolved or diffused in the
sulphate solution be of a more or less pasty nature, and not liquid or too fluent,
as in such cases, on adding the precipitating element, the gelatinous hydrate
would not be held diffused in a homogeneous manner throughout the adhesive mass,
but would separate and gravitate in a basic layer and thus defeat one of the main
objects of this invention. Hence in cases where other adhesive substances are
substituted for the starch, which are more soluble than starch, such, for example,
as dextrine, a much larger proportion must be used relatively to the volume of
water to get the dense or pasty consistency described which is necessary to hold up
the gelatinous alumina. Thus, where two pounds of starch to the gallon of water
-more or less-are ample for this purpose in the model formula, yet more than
twice or thrice this proportion of a very soluble adhesive substance would be
required to get the dense or viscous consistency to suspend the gelatinous hydrate
as will be readily understood.
It will be noted that an essential feature of this invention consists in an
adhesive paste composed of a starchy or primary adhesive substance in aqueous
solution impregnated with a large percentage of gelatinous alumina diffused
through the adhesive solution and imparting a non-fluid or gelatinous consistency
thereto. Hence in some cases the gelatinous hydrate may be formed or prepared
separately and then mixed with a solution of the adhesive matter but the preferred
process described is simpler, more direct, less expensive, and gives better results.
My correspondent does not limit himself, however, to any exact proportions of
the gelatinous hydrate or metallic oxide, more or less, relatively to the adhesive
substance, except such a substantial proportion as materially affects the consistency
of the compound and imparts a decided body thereto; or such a proportion, which,
while increasing the body, produces a positively white color in the product, as this
is a distinguishing novel feature in this invention.
Any salt having a digesting action with the qualities described may be used in
this process, but the simple salts of alumina are found to be the best for the
purpose of this invention. The double salts, or common alums may be used, but
most of them, particularly ammonia alum, have little digesting action on starch
as compared with sulphate of alumina, their efficiency being about one half that
of the sulphate weight for weight. In the case of the sulphate of alumina, however,
it is found that the digesting action is very positive and not only with the.com-
mercial salt but with the chemically pure salt which would seem to indicate that
the digesting action is not due to free acid or acidity in the salt, but purely to the
action of the salt per se.
I may mention a few other metallic salts which have a decided digesting action
on starch and which may sometimes be used, such as the bisulphates of magnesia,
potassium, &c., and also the binoxalates, but none of these is as effective as the

page_text: 5
salts of alumina. In the case of the other metallic salts which give very white
and soft flocculent precipitates, such as the sulphate of zinc, magnesia, &c., but
whose digesting action on starch is not very strong, a little free acid may be added
to their solutions to promote the digesting action. This acid will afterwards be
neutralized by the precipitating element or alkaline salt added in the process of
completing the paste as already described.
My correspondent does not limit himself to the specific list of salts mentioned as
any other salt which will digest starch and which will produce on decomposition
a gelatinous or soft flocculent precipitate will be an equivalent of the preferred
salts of alumina. It will be noted that not only does the precipitate from the
decomposed salts referred to add body to the adhesive compound, but also imparts
in a remarkable degree a very brilliant white color. Some salts like the salts of
zinc and magnesia will not add so much body as the salts of alumina but will add a
very brilliant white color, whereas the salts of alumina greatly add to both the
body and the whiteness of the product, which are very desirable and novel features
in the present process of paste manufacture.
It will be noted that in the preferred formula. not only is the sulphate of alumina
used as a digesting agent, and when decomposed as an important contributory
adhesive element, but that it is used in a large proportion relatively to the starch.
as this is necessary both for effective digestion and the other purpose mentioned.
The sulphate, however, may be used in a much smaller proportion than one-half
of the starch. but will not have marked efficiency as a digester much below one
eighth (%) of the weight of the starch.
It is of course well known that alums have been commonly used in making
starch and flour pastes, but always in a very small proportion, and chiefly for their
antiseptic qualities and not with any of the obiects in view as are presented in
this invention, and without accomplishing any of the results. or being capable of
producing such results, as I have set forth, as in these cases the alum has not been
used in sufficient proportion to digest the starch and the alumina is not free and
forms no substantial part of the adhesive mass which materially affects its color
and consistency as in this invention.
Tt is much preferred to conduct the digestion. as described, at a temperature
below the boiling point in open vessels. but if it is desired to conduct it at a
higher temperature in closed vessels. the digesting action will of course be stronger
and require less time for its completion, and less of the digesting salt, as will be
readily understood.
It will be seen that the first and simplest stage of the invention consists of the
mixture of dry or raw starch and the sulphate of alumina or other digesting salt
forming a prepared paste nowder which is a material improvement on that paste
powder shown in Boult (Higgins) former British Patent No. 9108 of April 9.
1897. In that natent, the chief digestive agents are liquid corrosive acids with
which the starch is moistened or impregnated. In the present case an entirely
dry granulated or powdered digesting salt, such as the sulphate of alumina, is
mixed with the starch in large proportion. This has the great advantage of pro-
ducing a mixture which is perfectly safe to handle under all conditions. is
innocuous and non-corrosive in any package in which it may be placed. and secures
other valuable qualities when the powder is dissolved and neutralized, as already
set forth.
The gallon herein referred to is the American gallon of 128 fluid ounces.
Having now particularly described and ascertained the nature of the said inven-
tion, 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: -
1st. A compound consisting of starch in combination with a digesting salt
sufficient to digest or convert the starch when the two are dissolved in hot or boiling
water, substantially as herein set forth.

page_text: 2nd. A compound consisting of starch in combination with a salt of alumina
sufficient to digest or liquefy the starch when the two are dissolved in hot or boiling
water, substantially as herein set forth.
3rd. A compound consisting of starch in combination with sulphate of alumina
sufficient to digest or liquefy the starch when the two are dissolved in hot or boiling
water, substantially as herein set forth.
.
4th. An adhesive compound consisting of a finely divided adhesive substance in
combination with a salt of alumina or its equivalent, the salt being in the propor-
tion of one eighth or more of the weight of the adhesive, substantially as herein
set forth.
5th. An adhesive compound consisting of starch, or equivalent finely divided
adhesive matter, in combination with a salt of alumina or its equivalent in such
proportion as will produce on solution and decomposition a substantial mass of
gelatinous hydrate, substantially as and for the purpose set forth.
6th. An improved adhesive substance, consisting of starch digested in a solu-
tion of a salt of alumina, or its equivalent to a non-gelatinous state, substantially
as herein set forth.
7th. An adhesive compound formed of a solution of a salt of alumina or its
equivalent, an adhesive substance dissolved or diffused therein, and a precipitating
element producing a flocculent or gelatinous precipitate throughout the adhesive
mass in the effective proportion herein specified, substantially ás and for the
purpose set forth.
8th. An improved adhesive compound, consisting of a solution of a salt of alumina
or its equivalent, a starchy or adhesive substance dissolved or diffused therein, and
an alkaline substance added thereto, in substantially the proportion herein set forth.
9th. An improved adhesive compound consisting of a starchy or adhesive sub-
stance diffused or dissolved in a solution of a salt of alumina or its equivalent, and
an alkaline borate added thereto, in substantially the proportion herein set forth.
10th. An improved adhesive paste consisting of a starchy or adhesive substance
in aqueous solution, in combination with gelatinous alumina diffused through the
said solution and forming a substantial part of the mass and in such proportion
to the primary adhesive matter as to impart a non-fluid or gelatinous consistency
to the mixture, substantially as herein set forth.
11th. An improved adhesive paste formed of digested or non-gelatinous starch in
aqueous solution, in combination with a gelatinous hydrate such as gelatine
alumina diffused through the same and in such proportion as to impart a non-
fluid consistency to the said solution, substantially as and for the purpose set forth.
12th. A starch or flour paste impregnated with a gelatinous hydrate such as
gelatinous alumina diffused through the same and in proportion relatively to the
starch or flour as to form a substantial part of the adhesive mass, imparting body
and non-fluidity thereto, substantially as and for the purpose herein set forth.
13th. A paste formed of a salt of alumina, or its equivalent, water, and a starchy
or adhesive substance, the salt being about one-eighth or more of the weight of
the starch, substantially as herein described.
.
14th. A paste formed of a salt of alumina or its equivalent, water, and a starchy
or adhesive substance, the salt being about one-eighth or more of the weight of
the starch, and a precipitating element sufficient to neutralize the said salt or
nearly so, substantially as and for the purposes set forth.
15th. The process herein described for producing an adhesive paste, viz., digest-
ing starch in a hot solution of a salt of alumina till it becomes liquefied or non-
gelatinous and then arresting the digestion and cooling the solution till it assumes
a pasty form, substantially as herein set forth..
16th. The process of producing an adhesive paste, viz., dissolving or digesting a
starchy or adhesive substance in solution of salt of alumina or its equivalent, then
gradually adding an alkaline salt and intimately mixing the same and thereby
producing a soft or gelatinous precipitate throughout the adhesive mass, substan-
tially as herein set forth.

page_text: 17th. The process herein described of treating starch in a hot solution of a salt
of alumina or its equivalent until a paste is formed, and then adding an alkaline
substance causing a precipitate of gelatinous alumina to become diffused through
and combined with the said paste, substantially as herein set forth.
Doted this 6th day of Santamban 1809