close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2113533

код для вставки
Patented Apr. 5, 1938
2,113,533
UNITED ‘STATES
‘PATENT OFFICE
2,113,533
RESTRAINT 0F CRYSTALLIZATION or IN- ’ _
ORGANIC coLLoms IN AQUEOUS AS802... , ~
CIATION
Willis A. Boughton, Cambridge, and William R.
Mans?eld, Boston, Mass, assignors to New
England Mica 00., Waltham, Mass, at corpora
tion of Massachusetts
No Drawing. Application September-4, 1935,
Serial No. 39,168
25 Claims. (Cl. 154-25)
This invention relates to the restraint of crys
tallization of inorganic colloids in aqueous asso
ciation, more particularly when used as bonding
agents for discrete particles of matter, bythe
5 conjoint use of crystallization restraining sub
stances associated with the inorganic colloids, and
- of the application of controlled pressure and ele
vated temperatures to products being bonded
with the inorganic colloids during the process of
10
manufacture.
,
~
An object of the invention is to provide a
process of restraining crystallization in the inor
ganic colloid bonding agent used to bond discrete
particles of matter by the application of con
15 trolled pressures at temperatures increasing from
normal to upwards of 500° C., the pressure serv
ing to retard or prevent the elimination of water
from the bonding agent, and thereby maintain
the inorganic bonding compound in the colloidal
state.
20
'
A further object is to provide a process of re
straining crystallization in the inorganic colloid
bonding agent used in the bonding of mica ?akes
into fabricated sheets, tubes, special shapes, etc.,
. by subjecting the mica product being bonded to
the controlled application of pressure and desired
.
A further object is to provide a process of
bonding mica ?akes by which products are pro
duced which maintain a. high electrical resist
ance, do not carbonize, and are mechanically
'
4
In a search for new and useful binders for mica
pieces, and other discrete particles of matter, we
have recently developed a series of colloidal inor
ganic bonding compositions; (see, for example,
U. S. Patent #2,004,030, which discloses a plural
ity of such colloidal substances including sodium
metaphosphate, NaPOa; glacial phosphoric acid,
HPOa; sodium monoborate, NaBOz; other .alkali
metaphosphates and monoborates, vsuch as the
respective ammonium, lithium, and potassium
compounds; also a few other chemically related
compounds, also a variety of the salts of the ele
ment beryllium including beryllium sulphate
which is preferably slightly basic due to the pres
ence of a slight excess of dissolved beryllium ox
ide or carbonate). The more successful use of
55
and also sodium silicate, and was entitled
“Method of restraining crystallization of dis
solved inorganic compounds in concentrated solu
tions”, Serial Number 546,154; ?led June 22,
1931, now Patent 2,016,274, dated Oct; 8, 1935.
l0
Our experiments of that time were made in
open dishes, (i. e. not under pressure) with the
commercial material then available, and yielded
results that indicated so de?nitely a tendency to
crystallize when more than ten percent of crys 15
tallization restraining material was present, that
we then assumed this percentage to be the maxi
mum operable proportion under all conditions,
and that larger proportions would impair the
quality of the products obtained.
7
In this earlier work the proportion. of crys
20
tallization restraining substances was, therefore,
limited to less than ten percent, as we then be
lieved this to be the maximum operable propor
tion. Later work with apparently a better qual
25
proach a reversal of percentages, namely ten
percent of colloidal inorganic bonding substance
and ninety percent of crystallization restraining 30
material, provided that the pressure is su?lclent
and is applied while the temperature is- being
increased from about room temperature to the
maximum temperature of manufacture. In
?cation.
50
ing the above inorganic colloidal bonding agents.
the otherwise dehydration of the aqueous inor
ganic colloidal association used as the bonding
durable.
45
one or more crystallization restraining sub
stances in the bonding compositions; and as one
result of our earlier work, an application for
U. S. patent was ?led, said application disclos
ity of material has shown, however, that the per,
35 _ Other objects of the invention will be apparent
' to those skilled in the art upon reading the speci
40
-
temperatures, thereby retarding or preventing
agent.
"30
'
centage may be greatly increased and even ap
other words, pressure on the colloidal binder dur- 35
ing the manufacture of bonded products is an
essential factor in the restraint of crystallization
of inorganic colloid bonding materials, as well as
the selected crystallization restraining salts de
scribed in the earlier application, (Serial Number 40
546,154, now Patent 2,016,274), and conforming
to the criteria there listed. This pressure prob-.
ably acts to‘ retard or prevent the escape of the
colloidally associated water, and to maintain the
dissolved salts in the colloidal state. The present 45
application for patent, therefore, deals with pres
sure as such an essential factor,_and the relation
of pressure to the proportion of crystallization
restraining material that may be successfully
used, rather than to the use of the crystallization 50'
restraining materials themselvesin minor quan
titles and in, the absence of appropriate pressures.
In some of the earlier work of this series, (U. 8.
1,975,079; and 2,004,030, for example),
these compositionsinvolves the incorporation of -Patents
the e?ect of pressure on restraint of crystalliza 55
2
.
2,113,533
tion was noted, but as evident from these patents
additional temperature increase of upwards of
the work there mentioned was done at the same
time as the work for the noted application
(546,154, now Patent 2,016,274) on Restraint of
150° C. in the case of sodium monoborate; and
to temperatures upwards of 500° C. with sodium
metaphosphate. We ?nd, therefore, for desir
able concentrations of crystallization restraining
substances above about ten percent, and for
intermediate temperatures at which there is
still residual water in the colloidal binder, pres
crystallization; the application covered by Patent
Number 1,975,079, and the application Serial
Number 546,154, now Patent 2,016,274, being ?led
on the same day. These earlier references to the
aid of pressure referred therefore to the concen
10 trations of crystallization restraining material
then thought to be 'the maximum operable,
namely, under ten percent, at which crystalliza
tion was largely restrained whether or not pres
sure was applied. The present application refers
15 .to the use of much higher concentrations of crys
tallization restraining materials with which, when
open heating is used, crystallization has been
found to occur, but when pressure is employed
while heat is applied to the product being bonded,
20 crystallization is positively restrained, as shown
in" the tables given later.
As a result of the present work the properties
of the fabricated products have been consider
sure sufficient to maintain the inorganic com
pound in the colloidal state is an essential fac
tor in the restraint of crystallization.
As described above, the earlier work referred
to concentrations of crystallization restraining
substances of ten percent or less, while the pres
tions of crystallization restraining materials are
present and the full crystallization restraining
effect of the added material can be utilized.
Crystallization temperatures of sodium
\
metaphosphates
Crystallization temperatures 25
Concentrations of '
crystallization restraining materials now actu
ally employed in some products are in the neigh
20
TABLE I
ably improved, the improvements considerably
25 enhancing their usefulness.
15
ent work involves the effect of pressure in re
straining crystallization when higherconcentra
Crystallization
NaPO;
restraining
mammal
borhood of twenty percent, and the pressures
gslavgfgggs‘
Open dish
applied thereto are from about twenty-?ve
pressure per
square inch
:!= about 25° 0.
30 pounds to upwards of two hundred and ?fty
pounds per square vinch. The products are al
lowed to cool under pressure.
The bonded mica plates, for example, as now
obtained, aremuch superior to those heretofore
obtained, are extraordinarily clear, well inte
grated and adhered, permanent, of maximum
dielectric strength, and high thermal resistance.
Because of their better integration they may be
more easily cut and punched. Molding at inter
mediate temperatures is more easily done. Fur
thermore, they permit more latitude in processes
of manufacture, such as less exact temperature
control and greater ease of handling in interme
diate stages. Naturally, also, there is a slight
45 economy in the cost of the colloidal constituent
of the mixed binder.
We believe that the im
Percent
Percent
°C.
0
°C.
, 120
9'
18"‘
34"
41
81
Below 300
315
333
Above 360
Above 360
Above 360
' Potassium hydroxide.
I
480
540
540 35
540
.
" Potassium hydroxide and diammonium orthophosphate.
TABLE 11
40
Corresponding results vobtained with sodium
monoborate
Crystallization temperatures
45
Crystallization
NaBOg
restraining
material
provement in physical properties is the direct
gggzlggdgf
Open dish
pressure per
square inch
=i= about 25° C.'
result of the use of higher concentrations of
crystallization restraining material made possible
50
50 only by employment of such pressures during the
Percent
heating process that constitute solution main
taining pressures.
.
°C.
'
‘
The colloidal bonding substances referred to
°C'.
0
108
260
10
30
114
121
135
132
315
315
315
315
herein are alkali metal metaphosphates, and al
55
kali metal monoborates, and are preferably lim
ited to two, namely, sodium metaphosphate, and
sodium monoborate, and which may be used
singly or mixed; the bonding and other proper
ties of these substances having been found to be
highly advantageous, and their tendency to crys
tallize at higher temperatures being found to be
markedly restrainable. We have found by ex
perimentation that in the absence of pressure
each‘ of these substances (in its commercially
available form) in colloidal aqueous condition
TABLE III
7 Corresponding results for a mixture of two parts
of sodium metaphosphate and one part of
sodium monoborate-crystallization tempera
tures of the above mixture
Colloidal mixture
-
Crystallization
restrainin’g
matenal
65
gsgvgggsdzf
Open dish
pressure per
square inch
:1: about 25° 0.
Percent
Percent
70 incorporation of ten percent or- less of crystalli
zation restraining materials as described in the
earlier application (Serial Number 546,154, now
Patent 2,016,274), and shown here; but when
pressure is applied and the temperature then
1 increased, crystallization is restrained for an
60
.
Crystallization temperatures
‘ may develop crystallization spontaneously at a
temperature markedly but not greatly above the
boiling point of water. The temperature at which
crystallization begins is de?nitely increased upon
30
0
10
30
50
80
' Dipotassium orthophosphate.
°C’.
108
111
118
123
130
“0.
345
370
425
315
315
70
3
2,118,583
It is evident therefore that in therestraint
of crystallization of these inorganic colloids, con
taining larger proportions of crystallization re
creasingly elevated temperatures, from about ten;
percent to about ninety percent by weight of the
bonding agent of a compatible compound hav
straining material, heating under pressure is an
essential positive factor in that the'inorganic
compounds are thereby maintained in the 001-,
loidal state. It is our belief that this is due to
ing the property of restraining crystal develop
the restraint of thermal dehydration physically
vated temperatures until a desired degree of de
hydration of the aqueous colloidal bonding agent
by the applied pressure, thus maintaining the col
ment in said viscous colloidal association, and ,
thereafter e?'ecting the ?nal bonding by subject
ing the said built-up assembly to increasingly ele
10 loidality of the bonding- material (upon which . has been attained and simultaneously to pres
its bonding properties depend at temperatures
below that of anhydrous fusion to a glass); and
therefore the effect might perhaps equally well be
called “Restraint of dehydration of inorganic col
15 loidal binders ‘by continued application of pres
sure during progressive elevation of tempera
ture.”
This matter of dehydration and loss of colloidal
the assembly, during the ?nal bonding operation, 15
is subjected simultaneously to controlled pres
sures from moderate pressures to upwards of
about 250 pounds per square inch, and to con
adhesive condition is one that is not even now
20 wholly clear, involving as it does, properties and
trolled heat of from about 100° C. to upwards of
study. But we believe as a result of our work
over many. years that, and as previously stated,
the assembly, during the ?nal bonding operation,
adhesive colloidality in these inorganic materials
25 at temperatures below that of complete dehydra
tion is intrinsically associated with the retention
sures from about 150 pounds per square inch to
conditions not subject to the usual methods of
of at least small proportions of water. , If this
10
sure su?icient to maintain the said bonding agent
in a colloidal state, and cooling the ?nally
bonded product while under pressure.
2. The method according to claim 1, in which
about 500° C.
,
3. The method according to claim 1, in which
20
is subjected simultaneously to controlled pres~
about 215 pounds per square inch, and to con
trolled heat of from about 160° C. to about
170° C.
.
4. The method of cementing discrete pieces to
water is lost, or enters into ordinary chemical
produce built-up products, which comprises
combination, crystallization ensues and adhesive
ness is lost. Sodium metaphosphate appears to bonding said pieces into a preliminary built-up 30
assembly with a bonding agent which is prepared
hold its colloidal water more strongly than sodi
um monoborate, which explains the lower value by incorporating in a viscous colloidal aqueous‘
for the crystallization temperature of the latter association of at least one dissolved inorganic salt
substance both_ alone, and in the 331/3 percent . selected from a group consisting of alkali metal
mixture
of said sodium monoborate with sodium metaphosphate, and alkali metal monoborate, the 35
35
metaphosphate.
,
For actual commercial production the pressure
used varies from 150 to about 215 pounds per
square inch. The e?ect of restraint of crystal
40 lization has, however, been followed from pres
sures as low as about 25 pounds per square inch
to as high as 1000 pounds per square inch; that
is, pressure on either the high or the low side of
those employed commercially functions to re
said association having the property of bonding
said pieces and of spontaneously developing crys
tallization at increasingly elevated temperatures,
from about ten percent to about ninety percent
by weight of the bonding agent of a compatible 40
compound having the property of restraining
crystal development in said viscous colloidal as
sociation, and thereafter e?ecting the ?nal bond
,ing by subjecting the said built-up assembly to
increasingly elevated temperatures until a desired 45
degree of dehydration of the aqueous colloidal
is one of the primary factors in the restraint of - bonding agent has been attained and simulta
crystallization; and is of equal importance to neously to pressure su?icient to maintain the said
the selection of added crystallization restraining bonding agent in a colloidal state, and cooling the
?nally bonded product while under pressure.
50 materials corresponding to the criteria given in‘
5. The method according to claim 4, in which 50
the application Serial No. 546,154, now Patent
the
inorganic salts in said group are sodium salts,
2,016,274. Pressure in practically any degree
and in which the assembly, during the ?nal bond
above normal appears to function in this way.
The crystallization restraining substances ing operation, is subjected simultaneously to con
strain crystallization of these bonding materials.
Thus it must be recognized that pressure alone
55 mentioned in the tables, namely, potassium hy
droxide, and di-ammonium and dipotassium or
thophosphate, are not the only ones that might
be used to give similar effects. The criteria
for selection of such substances are given in the
60 earlier\application Serial No. 546,154, now Patent
2,016,274. Among possible substitutes for the
substances given above, therefore, are potassium
carbonate, disodium orthophosphate, or a mix
ture of potassium carbonate, disodium ortho
65 phosphate, or a mixture of potassium carbonate
and orthophosphoric acid.
We claim—
1. The method of cementing discrete pieces to
produce built-up products, which comprises
70 bonding said pieces into a preliminary built-up
trolled pressures from moderate pressures to up
wards of about 250 pounds per square inch, and
to controlled heat of from about 100° C. to up
wards of about 500° C. ’
I
'
6. The method according toclaim 4, in which
the inorganic salts in said group are sodium salts, 60
and in which the assembly, during the ?nal bond
ing operation, is subjected simultaneously to con-.
trolled pressures of from about 150 pounds per
square inch, to about 215 pounds per square inch,
and to controlled heat of from about 160° C. to 65
about. 170° C.
7. The method of cementing discrete pieces to
product built-up products, which comprises
bonding said pieces into a preliminary built-up
assembly with a bonding agent which is prepared 70
assembly with a bonding agent which is pre
pared by incorporating in a viscous colloidal
by incorporating in a viscous colloidal aqueous
aqueous association of a dissolved inorganic salt
selected from a ?rst group consisting of alkali
metal metaphosphate, and alkali metal mono
having the property of bonding said pieces and
of spontaneously developing crystallization at in
55
association of at least one dissolved inorganic salt
borate, the said association having the property
4
2,113,533
of' bonding said pieces and of spontaneously de
veloping crystallization at increasingly elevated
temperatures, from about ten percent to about
ninety percent by weight of the bonding agent
of at least one compatible compound selected
from a second group consisting of potassium hy
droxide, diammonium orthophosphate, and di
potassium orthophosphate, said compound hav
ing the property of restraining crystal develop
10 ment in said viscous colloidal association, and
thereafter e?ecting the ?nal bonding by sub
jecting the said built-up assembly to increasingly
elevated temperatures until a desired degree of
dehydration of the aqueous colloidal bonding
15 agent has been attained and simultaneously to
pressure su?icient to maintain the said bonding
agent in a colloidal state, and cooling the ?nally
bonded product while under pressure.
8. The method according to claim 7, in which
20 the inorganic salts in said ?rst group are sodium
salts, and in which the assembly, during the ?nal
bonding operation, is subjected simultaneously to
controlled pressures from moderate pressures to
upwards of about 250 pounds per square inch,
.25 and to controlled heat of from about 100° C. to
upwards of about 500° C.
.
9. The method according to claim '7, in which
the inorganic salts in said ?rst group are sodium
salts, and in which the assembly, during the ?nal
30 bonding operation, is subjected simultaneously to
controlled pressures of from about 150 pounds
per square inch, to about 215 pounds per square
inch, and to controlled heat of from about 160° C.
to about 170° C.
35
v
10. The method acording to claim 7, in which
the inorganic salts selected from the ?rst group >
loidal state, and cooling the ?nally bonded prod
uct while under pressure.
13. The method according to claim 12, in which
the inorganic salts in said ?rst group are sodium
salts, and in which the assembly, during the ?nal
bonding operation, is subjected to controlled pres
sures from moderate pressures to upwards of
about 250 pounds per square inch, and to con
trolled heat of from about 100° C. to upwards of
about 500° C.
14. The method according toi claim 12, in which
10'
the inorganic salts in said ?rst group are sodium
salts, and in which the assembly, during the ?nal
bonding operation, is subjected to controlled
pressures of from about 150 pounds per square 15
inch to about 215 pounds per square inch, and to
controlled heat of from about 160° C. to about
170° C.
15. The method according to claim 12, in which
the inorganicsalts selected from the ?rst group 20
are in the proportion of two parts of sodium
metaphosphate and one part of sodium mono
borate, and one part of an orthophosphate se
lected from the second group.
16. The method according to claim 12, in 25
which the inorganic salts selected from the ?rst
group ‘are in the proportion of two parts of sodi
um metaphosphate and one part of sodium
monoborate, and one part of dipotassium ortho
phosphate from the second group.
30
17. The method in accordance with claim 1, in
which the discrete pieces are mica ?akes, and
the ultimate products are built-up mica prod
ucts, and in which the assembly during the ?nal
bonding operation is subjected to controlled pres 35
sures from moderate pressures to selected pres
sures upwards to about 250 pounds per square
are in‘ the proportion of two parts of sodium meta
phosphate and one part of sodium monoborate, inch, and to controlled heat of from about 100°
and one part of an orthophosphate selected from ~ C. to selected temperatures upwards to about
40 the second group.
11. The method according to claim 7, in which
the inorganic salts selected from the ?rst group.
are in the proportion of two parts of sodium‘;
metaphosphate and one part‘of sodium mono
45 borate, and one part of dipotassium orthophos
phate selected from the second group.
12. The method of cementing discrete pieces
to produce built-up products, which comprises
bonding said pieces into a preliminary built-up
50 assembly with a bonding agent which is prepared
by incorporating in a viscous colloidal aqueous
association of at least one dissolved inorganic salt
selected from a ?rst group consisting of alkali
metal metaphosphate, and alkali metal mono
55 borate, the said association having the property
of bonding said pieces and. of spontaneously de
veloping crystallization at increasingly elevated
temperatures, said association comprising from
60
about seventy-?ve percent to about twenty-?ve
percent by weight of the bonding agent, and from
about twenty-?ve percent to about seventy-?ve
percent by weight of the bonding agent of at
least one compatible compound selected from a
65 second group consisting of potassium hydroxide,
diammonium orthophosphate, and dipotassium
orthophosphate, said compound having the prop
erty of restraining crystal development in said
500° C.
.
18. The method according to claim 4, in which
the discrete pieces are mica ?akes, andthe ul
timate products are built-up mica products and
in which the assembly during the ?nal bonding
operation is subjected to controlled pressures 45
from moderate pressures to selected pressures
upwards to about 250 pounds per square inch,
and to controlled heat of from about 100° C. to
selected temperatures upwards to about, 500° C.
19. The method according to claim 7, in which 60
the discrete pieces are mica ?akes, and the ulti
mate products are built-up mica products, and
in which‘the assembly during the ?nal bonding
operation is subjected to controlled pressures
from moderate pressures to selected pressures 55
upwards to vabout 250 pounds per square inch,
and to controlled heat of from about 100° C. to
selected temperatures upwards to about 500° C.
20. The method according to claim '12, in
which the discrete pieces are mica ?akes, and so
the ultimate products are built-up mica products,
and in which the assembly during the ?nal bond
ing' operation is subjected to controlled pressures
from moderate pressures to selected pressures
upwards to about 250 pounds per square inch, and 65
to controlled heat of from about 100° C. to se
lected temperatures upwards to about 500° C.
21. The method of maintaining in the colloidal
viscous colloidal association, and thereafter ef 'state the bonding agent of a bonded product
70 fecting the ?nal bonding by subjecting the said made up of discrete pieces preliminarily bonded 70
built-up assembly to increasingly-elevated tem
with an inorganic viscous colloidal aqueous as
peratures until a desired degree of dehydration of sociation having a tendency to devolop crystals,
the aqueous colloidal bonding agent has been at
which comprises incorporating in said viscous col
tained and simultaneously to pressures su?icient _ loidal aqueous association from about ten per-~
76 to maintain the said bonding agent in a col
cent to about ninety percent by weight of the
75
2,118,583
bonding agent of a compatible compound con
sisting of, an inorganic crystallization restraining
agent, and thereafter ?nally bonding said prod
uct by subjecting the same to controlled pres
sures from moderate pressures to selected pres
sures upwards'to 250 pounds per square inch, and
to controlled heat of from about 100° C. to se
lected temperatures upwards to about 500° C.
until a desired degree of dehydration of the aque
10 ous colloidal bonding agent has been attained,
and thereafter cooling the bonded product while
under pressure
22. The method of maintaining in the colloidal
state the bonding agent of a bonded product
15 made up of discrete pieces preliminarily bonded
with an inorganic viscous colloidal aqueous as
sociation having a tendency to develop crystals,
said association comprising at least one dissolved
salt selected from a ?rst group consisting of al
20 kali
metal ‘ metaphosphate
and
alkali
metal
monoborate, which comprises incorporating in
said viscous colloidal aqueous association from
about ten percent to about ninety percent by
weight of the bonding agent of an inorganic crys
25 tallization restraining agent selected from a sec
ond group consisting of potassium hydroxide, di
ammonium orthophosphate, and dipotassium or
thophosphate, and thereafter ?nally bonding
said product by subjecting the same to controlled
30 pressures from moderate pressures to selected
_ pressures upwards
to about
250 pounds per
square inch, and to controlled heat of from about
100° C. to selected temperatures upwards to
about 500° C. until a desired degree of dehydra
35 tion of the aqueous colloidal bonding agent has
been attained, and thereafter cooling the bonded
product while under pressure.
23. The method according to claim 22, in
which the discrete pieces are mica ?akes, and the
40 ultimate products are built-up mica products.
24. The method of preventing crystallization
5,
of colloidal'binder components in an inorganic
viscous colloidal aqueous association, which com
prises adding to said aqueous association and dis
solving therein from ten percent to upwards of
ninety percent by weight of the said colloidal OW
binder components of a compatible inorganic
compound having the property of preventing the
crystallization of the said dissolved colloidal bind
er components, con?ning limited quantities of
said aqueous viscous colloidal association between 10
surfaces and dehydrating said con?ned limited
quantities to a desired degree by'subjecting the
same to temperatures upwards to 500° C. and
simultaneously to pressures upwards to 250
pounds per square inch for a period of time suf
?cient to e?ect said dehydration and bond said
surfaces, and thereafter cooling said bonded sur
faces and bonding agent while under pressure.
25. The method of maintaining the aqueous
viscous inorganic colloidal bonding agent of a 20
built-up mica product bonded therewith free
from crystal development, which comprises incor
porating in said aqueous colloidal bonding agent
from ten percent to upwards of. ninety percent
of a dissolved compatible inorganic compound
having the property of preventing said crystal
development, bonding mica ?akes to produce said
built-up mica product with limited quantities of
said aqueous viscous inorganic colloidal bonding
agent containing said dissolved compatible com 30
pound, dehydrating said limited quantities of
said bonding agent to a desired degree by sub
jecting said mica ?akes and bonding agent to
temperatures upwards to 500° C. and simultane
ously to pressures upwards to 250 pounds per
square inch for a period of time sumcient to ef
fect said dehydration and bond said mica ?akes,
and thereafter cooling said bonded mica product
while under pressure. '
WILLIS A. BOUGHTON
' WILLIAM
R. MANSFIELD.
40
Документ
Категория
Без категории
Просмотров
0
Размер файла
764 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа