Note: Descriptions are shown in the official language in which they were submitted.
- ~L86~
- 1 LFM-7149
RIGID, WATER-RESISTANT PHOSPHATE CERAMIC MATERlALS
AND PROCESSES FOR PREPARING THEM
.. . .
The present invention relates to rigid,
water-resistant phosphate ceramic materials and more
10 particularly to rigid, water-resistant phosphate cera~ic
materials which do not require subsequent thermal
curing.
Background o the Invention
Refractory metal phospha~es have long ~een
recognized as useful building and insulatins materials.
Compositions comprising phosphoric acid, a metal oxide,
and metal silicates are known in the art; however,
composi~ions comprising these constituents and having
adequate strength are extremely difficult to prepare.
For examplel mixtures of aluminum oxide and.85
phosphoric acid are viscous and difficult to handle. I~
such mixtures are diluted with water, the ease of
handling is greatly improved; nevertheless, when
silicate, e.g. calcium silicate, is added and the
~5 resulting phosphate is thermally cured to drive off
excess water, the reractory material obtained has
relatively poor tensile strength. Alternatively, if all
. . . of the somponents are mixed to~ether at once without
using additional ~ater, a rapid reaction ensues which
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cannot be handled under normal manufacturing
circumstances.
The Prior Art
Various phosphate compositions and processes
for preparing them are found in the prior art. For
example, U.S. Patent No. 2,992,930, dated July 18, 1961
to William Wheeler et al. discloses compositions
comprising powdered zirconium or aluminum oxides,
calcium silicate for foam stabilization, phosphoric
acid, a silica sol bonding agent and a blowing agent,
the composition being prepared by blending the dry
ingredients, adding the silica sol, stirring the mixture
with phosphoric acid and allowing the resulting foam to
become rigid. U.S. Patent No. 3,148,996, dated
September 15, 1964 to Mark Vukasovich et al. discloses
compositions which set into a rigid mass without heating
and which may be rendered porous by incorporation of gas
bubbles~ These compositions consist of water, an acid
phosphate consisting of phosphorus pentoxide and
calcium, aluminum or zirconium oxides, and finely
divided calcium silicate. They are formed by preparing
a visCous solution of water, phosphorus pentoxide'and an
appropriate metal oxide, adding calcium silicate to the
mixture and allowing it to partially hardenO Foaming is
then induced by adding an internal foaming agent or by
mechanically introducing gas bubbles. U.S. Patent Wo.
3,330,675, dated July 11, 1967 to Jules Mag'der discloses
compositions comprising acidic aluminum phosphate, the
carbonate, oxide, hydroxide or silicate of magnesium or
zirconium, and organic or inorganic gas producing
materials~ Similarly, other patent references disclose
related phosphate foams in which'a powdered metal is
incorporated into the acidic mixture, thereby-inducing
foaming through the release of hydrogen gas.
Although it is evident from these references
that substantial effort has bee~ expended to develop
useful phosphate foams, many-problems still exist. Most
of the prior art foams have poor bond strength, thereby
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rendering them unusable as building materials. Some are
moisture sensitive, many require heat curing to improve
bond s~rength, and most contain other additives desi~ned
to circumvent weakness problems; In addition, most
commercially manufactured foams contain blowing agents
which can increase the cost of the product and sometimes
- contribute to bond weakness.
Accordingly, one object of the present
invention is to provide strong, moisture-resistant
phospha.e ceramic materials which can be prepared
without the use of external heat.
Yet another object of the present invention is
to provide processes for the preparation of rigid
phosphate foams without the use of added blowing agents~
Still another object of the present invention
is to provide processes for the convenient and
continuous production of phosphate foam whereby slumping
of the foam is avoided.
These and other advantages of the present
invention will become a~parent from the description of
the invention which follows.
Summary of the Invention
The present invention concerns rigid,
water-resistant phosphate ceramic materials which may be
prepared Erom compohents comprising metal oxide, calcium
silicate, and phosphoric acid. By prereacting a por~ion
of the metal oxide with the phosphoric acid and/or by
adjusting the temperature of the acid solution when it
is combined with the other ingredients, the character of
the res~lting product can be controlled to gi~e foamed
or unfoamed phosphate ceramic material.
Detailed Descriptlon of Preferred Embodiments
Xn one embodiment, the process of the present
invention comprises the steps of (1) selecting at least
one metal oxide from the group consisting of A12O3, MgOt
CaO or ZnO or the hydrates thereof, said metal oxide
comprising a total of from about 11 to about 65 parts by
weight calculated on an anhydrous basis; (2) preparinq a
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_ 4 _ LFM-7149
reaction solution comprising a portion of said metal
oxide and from about 80 to about 190 parts by weiqht oE
a phosphoric acid solution comprisinq the equivalent of
from about 35 to about 75% by weight of phosphorus
pentoxide based on the weight of the acid solution, the
water of hydration of said metal oxide being included
--- when calculating the phosphorus pentoxide content; (3)
preparing a mixture comprisiny the remainder of said
metal.oxide and about 100 parts by weight of calcium
silicate. The temperature of said reaction solution is
adjusted to a desired value and the mixture is
prvportionally intermixed with said reaction solution.
The resulting intermixed material is placed in a desired
configuration and the components thereof are allowed to
interact. The amount of metal oxide used to prepare the
reaction solution and the temperature of the reaction
solution are selected s~ as to approximately
predetermine the point in time at which said intermixed
material becomes rigid relative to the point in time at
which vaporization of the water occurs.
In a second embodiment the process of the
present invention comprises the steps of (i) preparing a
mixture comprising from about ll to about 65 parts by
weight calculated on an anhydrous basis of at least one
metal oxide selected from the group consistinq of Al2O3,
MgO, CaO or ZnO or the hydrates thereof, and about 100
parts by weight of calcium silicatè; and (2) preparing a
reaction solution comprising from about 80 to about 190
parts by weight of a phosphoric acid solution comprising
the equivalent oE from about 35 to about 75% by weight
of phosphorus pentoxide based on the weight of the acid
solution, the water of hydration of said metal oxide
being included when calculating the phosphorus pentoxide
content. The temperature of the reaction solution is
adjusted to a desired value and the solution is
proportionally .intermixed with said mixture. The
resulting intermixed material is placed in a desired
configuration and the components thereof are allowed to
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5 - LFM-7149
interact The temperature of the reaction solution is
selected so as to approximately predetermine the point
in time at which said intermixed material becomes rigid
relative to the point in time at which vaporization of
the water occurs.
In a third embodiment the present invention
comprises the steps~of (1) selecting at least one metal
oxide from the group consisting of A12O~, MgO, CaO or
ZnG or the hydrates thereof, said metal oxide comprising
a total of from about 11 to about 65 parts by weight
calculated on an anhydrous basis; (2) preparing a
reaction solution comprising a portion of said metal
oxide and from about 80 to about 190 parts by weight of
a phosphoric acid solution comprising the equivalent of
from about 35 to about 75~ by weight of phosphorus
pentoxide based on the weight of the acid solution, the
water of hydration of said met~l oxide bein~ included
whèn calculating the phosphorus pentoxide content; and
(3) preparing a mixture comprising the remainder of said
metal oxide and about 100 parts by weight of calcium
silicate. The mixture is proportionally intermixed with
said reaction solution and the resulting intermixed
material ls placed in a desired configuration where the
components thereof are allowed to interact. The amount
of metal oxide which is used to prepare the reaction
solution is selected so as to approximately predetermine
the point in time at which said intermixed material
becomes rigid relative to the point in time at which
vaporiæation of the water occurs.
In a fourth embodiment the present invention
comprises a composition suitable to provide a rigid,
water-resistant ~hosphate ceramic material, said
composition comprising (1) from about 11 to about 65
parts by weight calculated on an anhydrous basis of at
least one metal oxide selected from the group consistinq
of A12O3, MgO, ~aO or ZnO or the hydrates thereof; (2)
6~3~P
6 - LFM-7l49
from about 80 to about 190 parts by weight of a
phosphoric acid solution comprising the equivalent of
from about 35 to about 75% by weight of phosphorus
pentoxide based on the weight of the acid solution, the
water o hydration of said metal oxide being included
when calculating the phosphorus pen'oxide content; and
(3) about 100 parts by weight of calcium silicate.
In a fifth embodiment the present invention
comprises a rigid, water-resistant phosphate ceramic
material obtained by reacting (1) from about ll to
about 65 parts by weight calculated on an anhydrous
basis of at leas-t one metal oxide selected from the
group consisting of A12O3, MgO, CaO or ZnO or the
hydrates thereof, (2) fr~m about 80 to about 190 parts
by weight of a phosphoric acid solution comprising the
equivalent of from about 35 to about 75% by weight of
phosphorus pentoxide based on the weight of the acid
solution, the water of hydration of said metal oxide
being included when calculating the phosphorus pentoxide
content; and (3) about 100 parts by weight of calcium
silicate.
The components used to practice the present
invention are all commercially available. Calcium
silicate (100 parts by weight) is preferred in
practicing the present invention although other
silicates may also give satisfactory results. Calcium
silicate occurs naturally and is referred to as
wollastonite. Suitable foamed or unfoamed products can
be obtained when this material is used in powdered form
as described belo~. For making foams, the particle size
will preferably be sufficiently small that most of the
silicate passes through a 200-mesh Tyler Standard sieve.
A numher of metal oxides su~h as aluminum
oxide, magnesium oxide, calcium oxide and zinc oxide
may be used to obtain satisfactory phosphate ceramic
material. These oxides are used in powdered ~orm, with
finer particle-size oxides on the order oE 325 mesh
(Tyler Standard) or slnaller givin~ generally superior
~86~3~1
- 7 - LFM-7149
results. Hydrated forms of the oxide may also be u.sed
and in many instances are preferred. In the event that
a hydrate is used, the water of hydration must be taken
into account so as not to provide excess water for the
reaction. This may be conveniently done by including
the water of hydration when calculating the phosphorus
pentoxide content of the phosphoric acid solution.
From about 11 to about 65 parts by weight of
metal oxide, calculated on an anhydrous basis, in
relation to 100 parts of calcium silicate may be used to
practice the present invention; however, from about
13-26 parts of metal oxide is preferred and from about
15-20 parts is especiall~ preferred. The amount of
oxide which is used will depend on whether it is in
hydrated form and/or on its reactivity.
Anhydrous magnesium oxide reacts much more
rapidly with phosphoric acid than does anhydrous
aluminllm oxide. For example, the former will react
within minutes whereas the latter may require hours,
depending on the temperature of the acid solution If
hydrated forms are used, however, the disparity in the
reaction times is dramatically dimini.shed. Hydrated
magnesium oxide reacts more quickly than does anhvdrous
magnesium oxide, and it also reacts much more auickly
than hydrated aluminum oxide Nevertheless, hydrated
aluminum oxide is substantially more reactive than
anhydrous aluminum oxide for it reacts with the `
phosphoric acid solution within a matter of minutes,
rather than hours. The implications of the reaction
times will be set forth more ~ully below.
Suitable products can be obtained using any of
the indicated oxides, alone or in combination, bùt
anhydrous magnesium oxide (calcined) and hydrated
aluminum oxide are particularlv preferred to practic~
tne present invention. Magnesium oxide tends to
increase the strength and moisture resistance o~ the
~inal product whereas aluminum oxide tends to provide
superior settin~ characteristics~
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Phosphoric acid is availa~le in a variety of
concentrations, 85% being the most common concentration
for ortho-phosphoric acid. Other compositions, such as
polyphosphoric acid, which will yield phosphoric acid
upon dilution with water may also be satis~actory to
practice the present invention, provided that the
overall water content of the reaction system is not too
high. Tov much water must be avoided because products
will be obtained which, even though water resistant,
will have poor strength. On the other hand, too little
water is also detrimental, not only because intermixing
of the materials is difficult to achieve, but hecause,
in the case of foamed products, only hiqh density foams
are obtained.
As a ~eneral rule, the phosphoric acid will be
suitable if it contains tlle equivalent oE from about
35 to about 75~ by weight of phosphorus pentoxide based
on the weight of the acid solution. Preferably, the
equivalent of phosphorus pentoxide will be about 40-70~,
and more preferably about 4S-65%. The remaining portion
of the acid solution comprises water including, for
purposes o calculation, any water of hydration from the
metal oxide. From about 80 to about 190 parts by weight
of the acid solution may be used in practicing this
invention but preferably from about 90 to about 150
parts will be used, and more preferably from about 100
to about 130 parts of acid will be used.
Although the components used to practice the
present invention have long been used in the art, the
advantages to be derived when these components are
combined as disclosed herein have never been recognized.
It has been discovered that if the manner in which the
ingredients are combined is controlled and excess water
is avoided, a product will be obtained which requires no
3S heat curing and is water resistant. While applicant is
not bo~nd by any theory as to thè nature oE the
reactions involved in the present invention, two
separate yet related phenomena are apparently
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occurrin~; namely, vaporization of the water and
bonding of the materials. Heat generated by the
reactants vaporizes the water present whereby the water
vapor can act as a foaminq agent~ During approximately
the same time span, bonding or setting occurs which
results in the formation of a rigid ceramic-like
material. These two phenomena will be referred to
herein as "vaporization" or the "vaporization stage,"
and "setting" or the "setting stage," respectively.
To practice the present invention a reaction
solution is preferably prepared by addinq a desired
portion of the metal oxide to the phosphoric acid
solution. In addition, liquid additives such as
surfactants may also be incorporated into the reaction
solution. The remainder of the metal oxide and all of
the calcium silicate are then combined and mixed with
any solid additives, such as reinforcing fibers,
thickeners, coloring matter and the like. The
temperature of the reaction solution is preferably
adjusted to a desired value and the solution is
proportionally mixed with the remaining dry ingredients.
The intermixed material is then placed in a desired
configuration and the components of the system interact.
The products which are obtained do not require heat
curing and may be placed in boiling water without
adverse effect. Nevertheless, they are not heat
sensitive for samples have been heated to 1600F without
significant loss of strength.
It has been discovered that the relative
points in time at which vaporization and setting occur
will dictate the nature of the product which is
obtained. For-example, if the vaporization stage is
reached before the setting stage, the water vapor will
cause the mixture to foam before the mass becomes rigid.
Conversely, if setting occurs first, the material is
unable to foam and the water vapor escapes through the
interstitial spaces. The implications of the latter
se~uence of events will be set forth in more detail
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below, but in either case a product can be obtained
which does not require heat curing, yet is resistant to
water.
Two factors which contribute to the
aforementioned events are the amount of metal oxide
which is prereacted with the phosphoric acid and the
temperature of the reaction solution at the time it is
combined with the remaining dry ingredients. If only
one of these factors is controlled, a c~ramic-like
mater1al can still be produced. Nevertheless, it is
preferable to control both parameters to facilitate
handling and to obtain a superior prbduct.
~ ow these factors may be varied will be seen
Erom the followinq. Generally speaking, if relativelv
less of the metal oxide is prereacted with the
phosphoric acid, relatively more foaming will occur
during the subsequent mixing step before the mass of
materials become rigid, provided that the temperature o
the acid solution is not too low. Conversely, if
29 relatively more of the metal oxide is prereacted with
the phosphoric acid, less foaming will occur before the
mass beco~es rigid. If enough metal oxide is
prereacted, essentially no foaming will occur. This
result i~ apparently obtained because the preaddition of
the metal oxide tends to lengthen the duration of the
- exothermic reaction or reactions which vaporize the
water.
- The temperature of the reaction solution
during the subsequent mixing step can also siqnificantly
affect the resulting product. The higher the
temperature of this soluti~n, the more vigorous is the
evolution of water vapor and the sooner water
vaporization occurs when the reaction solution is mixed
with the remaining dry ingredients. Thus, if the
temperature is too high, the greater the likelihood of
obtaining foams wKich contain voids or wnich foam
rapidly and then slump. This effect may be mitigated
somewhat, however, by including a surfactant in the
reaction solution.
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6~3~D
11 - LFM-7149
If the temperature is too low, the exothermic
reaction may be suppressed so that no foaming will
occur. Furthermore, too low a temperature may be
detrimental because the material which is obtained might
have relatively weak bonding strength~ The optimum
temperature of the reaction solution can vary depending
on the reactants, but generalIy it has been found that a
tempera~ure range of about 35 to about 80F will give
satisfactory results. When making foams, the preferred
temperature range is about 38-45F, and most preferably
40F, unless a foaming agent is added as hereinafter set
forth.
In practice, other factors in addition to the
amount oE prereacted material and the temperature of the
acicl solution must be considered, many of which are
dependent on the type of product to be produced. When
making foams, the objective is to cause the foam to
reach a desired height at about the time setting occurs.
In essence, the water vaporization which causes the
foaming should be timed so that it yields a uniform cell
size in a product which is the right height and density
after settiny is complete. Cell size is affected bv the
rate at which the water vapor is given off and by the
viscosity of the acid solution. The viscosity, in turn,
depends on the type of oxide or oxides used, the
particle si~e of the oxide, and the temperature of the
acid solution.
Solutions having different viscosities are
obtained when the various oxides are dissolved in
phosphoric acid. For example, when increasin~ amounts
of magnesium oxide are added to one aliquot of a
standard strength ~e.g. 85~) acid solution, viscosities
are observed to vary from ca 50 cp to l,OOO cp at 72F.
However~ when comparable ~olar amounts of aluminum oxide
are added to a second aliquot of the same acid solution
at 72F, viscosities of from ca 50 cp to only 400 cp are
observedO To make superior foams, it is preferred that
the viscosity of the acid solution at the time of
~86~3~
- 12 - LFM-7149
intermixing with the remaining ingredients not exceed
about 400 cp. Thus, it will be seen that a second
limitation to the use of magnesium oxide, aside from its
tendency to vigorously cause foaming, i5 the viscosity
of the reaction solution whic:h results when it is used.
~ The higher the viscosity of the reaction
so~ution the poorer the mixing of the ingredients and
the poorer the foam quality oE the product that is
obtained. For that reason~ it is often desirable to use
more than one oxide. Thus, one oxide could be used to
prepare the reaction solution and another could be
combined with the calcium silicate. Alternatively, the
oxide could be used as a mixture, both for forming the
reaotion soIution and for mixin~ with the calcium
silicate. A variety of possibilities exist; therefore,
it is intende~ that all such possibilities be included
within the scope of the present invention, and the
present invention should not be limited to these two
illustrations.
The density of the final product will depend
to a great extent on the amount of metal oxide which is
used to form the reaction solution; namely, the more of
the metal oxide, ~he greater the density. As a general
rule, in the absence of added foaming agents, if from
about 0 to about 0.3 part of metal oxide for each one
part of P2O5 in the acid solution is used to form the
reaction solution, foams having densities of fro~ about
40 down to about 15 pounds per cubic foot will be
obtained. However, if more than about 0.3 part of
metal oxide i5 used, a non-foamed ceramic will be
anticipated. Nevertheless, practical considerations,
such as viscosity, afect the upper limit of prereacted
material; thus, usually not more than 50% of the metal
oxide can be conveniently prereacted.
Other considerations which aEfect the foams
are pàrticle size, surface properties and reinforcing
materials. A small and uniform particle siæe is ~uch
preferred to practice the present invention because o~
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the tendency of such material to promote fine cell
structure. As previously note~l, metal oxides which pass
throu~h a 325-mesh Tyler Standard sieve and calcium
silicate which passes throu~h a 200-mesh Tyler Standard
sieve are preferred.
Cell size also de]pends on the sur~ace
properties of the material and it is often helpful to
include one or more surfactants to promote cell
stabilityO Virtually any surfactant which is not
affected by the phosphoric acifl may be used. One
surfactant which has been found particularly
satisfactory is dimethylcocamine oxide which is sold by
Armak under the name Ara~ox DMC. Care must be taken in
handling this material, however, because it is a skin
and eye irritant.
Because foams are of a porous nature, they
tend to have lower tensile strength than unfoamed
materials~ Accordingly, it is often advisable to add
fibrous reinforcing material to strengthen the foam.
Polyester, glass, polypropylene and nylon, among others,
have been used with success, although the conditions
under which the final product will be used may influence
the selection ffl fiber. For example, for a high
temperature application, glass fibers would be much more
stable than would organi~ fibers. Generally, fiber
lengths of from 1/8" to 1" will be sui~able, with
approximately 1/2" fibers being especially suitable~
When preparing unfoamed phosphate ceramics,
factors such as particle size, viscosityr tem~erature
and surface properties become much less important
because c:ell structure is not a concern. Accordinqly,
coarser particle-si~e materials and a higher viscosity
of the reaction solution may be permissible~ subject
only to constraints imposed by the handleability of the
reactants. A much higher temperature for the reaction
solution may also be used becaose the unfoamed material
will not slump. Furthermore, no surfactant will be
required because there is no cell stability problem.
*Trademark
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Aside from these considerations, the objective
in preparing an unfoamed ceramic is comparable to that
of preparing a foamed material, the major diference
being that, with unfoamed materials, it i5 necessary to
postpone the vaporization stage until the mass has
become rigid, thus preventing expansion of the phosphate
material. This is convenien~ly accomplished by
prereacting a greater amount of the metal oxide.
However, care must be taken to ensure that the water can
escape from the unfoamed material. If the internal
pressure of the structure becomes too great due to water
pressure, the rigid ceramic can be cracked~ For this
reason, when preparing unfoamed phosphate ceramics, it
is often desirable to include porous fillers which
provide passageways through which the water vapor can
escape. Examples of fillers which are satisfactory are
vermiculite and perlite.
Surprisingly, I have also discovered that
satisfactory foamed products may be produced by
combining the techniques of the present invention with
foaming agents taught by the prior art. The prior art
contains references to the use of carbon dioxide or
carbon dioxide-producing materials and hydrogen or
hydrogen-producing materials, as well as other organic
or inorganic gas-producing materials, durin~ the
production of phosphate products. Such aqents may also
be used to advantage in producing the rigid, water-
resistant phosphate ceramics of the present invention.
Although virtually any prior art foaming agent
may be employed, the results that may be obtained are
exemplified by the use of various carbonates.
Carbonates such as MgCO3, CaC03, ZnC03, Li2C03 and the
like, or mixtures thereof, which produce .elatively
insoluble phosphates are preferred; however, MgCO3 is
especially preerred be~ause it typically produces a
foam having a relatively uniorm cell size and a
generally suitable denslty. Other carbonates such as
3 and K2C03 which produce relatively soluble
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phosphate salts may also be employed where leaching of
the phosphate from the resulting phosphate ceramic when
it is exposed to water will not be detrimental~
~hen using dry foaming agents, it is usually
desirable to mix them with the other dr~ ingredients
comprising the calcium silicate and a portion of the
metal oxide; however, these foaming agents may also be
added'separately. Because the foaming obtained in the
presence of such agents is not provided by water
vaporization, it is undesirable to have the exotherm
occur prior to setting. For that reason, it is usually
necessary to prereact a greater portion of the metal
oxide'with the phosphoric acid solution. Often this
will cause an undesirable increase in the viscosity of
15 the acid solution. Accordingly, when using an added ;~
foaming agent, it may be necessary to dilute the aci~
solution somewhat in order to control the viscosity.
~owever, care must be taken to avoid usin~ excess water
because the combination of using additional water and
prereacting more of the metal oxide tends to lower the
temperature of the exotherm, thereby increasing the
possibility of producing a phosphate ceramic with
unsati~factory performance characteris~ics.
As an additional consideration, the
temperature'of the reaction solution at the time of
intermixing with the dry components can o~ten be higher
when foaming is achieved using dry foaming agents rather
than using water vaporization because setting must occur
prior to the occurrence of the exothermic reaction.
Thus, when using dry foaming agents, it is often
desirable for the reaction solution to be within a
preferred temperature range of about 50 to 6noF rather
than the preferred range of about 38 to 45F referred to
earlier in connection with the water vaporization
foaming process.
Of course, it is also possible to use a li~uid
foaming agent such as a fluorinated hydrocarbon having a
boiling point lower than the temperature at which
36~3~
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setting of the foam occurs. Examples of such
hydrocarbons are Freon-ll or Freon-113 sold by duPont.
~ydrocarbons of this type may be added to and mixed with
the acid solution, or they may be added separately at
5 th~ time of intermixing Witil the solid ingredients.
Non~fluorinated hydrocarbons having an appropriate
boiling point may also be u~ed, but they are much less
desirable because of the inherent risk of fire
associated with their use.
~he manner of adding these foaming agents,
whe~her wet or dry, may be a matter of choice to the
artisan or it may depend on various factors such as the
type of product desired and/or the type of equipment
utilized. In certain circumstances, the method of use
may be controlled by the nature of the foaming agent.
For example, the carbonates react chemically with the
acid solution; thus, they cannot be added to the acid
solution at a point too early in the reaction sequence.
Conversely, fluorinated hydrocarbons produce foaming by
passing from a liquid to a gaseous state; thus, they may
be maintained in contact with the acid solution if the
temperature of the mixture remains sufficiently low. In
the lat~er case, however, it must be recognized that
- fluorinated hydrocarbons form a two-phase system with
the acid solution. Therefore, care should be taken to
ensure that the two-phase system is uniformly mixed
prior to intermixing with the solid ingredients.
Because the art discloses a wide variety of
materials which may be employed in various ways to
produce t:he phosphate ceramics of the present invention,
the term "foaming agent~,~ as used herein, is intended
to encompass all such materials, provided that thev
produce phosphate ceramics having the characteristics
previouly set forth.
The following examples, in which all parts are
expres~ed by weight, will be illustrative to Aemonstrate
the advantages of the present invention.
*Trademark
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17 - LFM-7149
~X~MPLES
Examl?le 1
A phosphate foam was prepared from the
following components:
Parts per
W ~ ~ 100 parts CaSlO~
23.3H2 14.42 3~.04
85% H3P4 41.58 104~0
~61.~% P2O5~
CaSiO3 40.0 100
Surfactant 0.04 0.1
If these relationships are calculated by
placing the metal oxide on an anhydrous basis and
includiny the water of hydration as part of the acid
solution, the followinq is obtained:
Parts per 100
Component Parts CaSi~3
Al23 23.56
75,9~ H3P4 116.5
Z0 ~ ~55% P2Os)
CaSiO3 100
Surfactant 0.1
The reaction solution was prepared by adding
1.04 parts of Al2O3~3~2O to 104 parts of phosphoric acid
and stirring the mixture with moderate agitation for
approximately 15 minutes until a clear solution was
obtained. The surfactant (0.1 part) was added to the
reaction solution, which was then cooled tG 40F. The
remaining dry ingredients (100 parts of calcium silicate
and 35 parts of a~uminum oxide trihydrate~ were mixed
together and fed into a Readco continuous processor.
The reaction solution was also fed into -the ~eadco mixer
through a different addition port. The ingredients were
proportionally mixed therein, dischar~ed onto a ~ovinq
*Trademark
~L~86~3~
- 18 - LFM-7149
belt covered with a scrim material and leveled. Foaming
began in approximately 1.5 minutes and the mass of
material became rigid in approximately 2 minutes. A
continuous block of foamed material 1 thick and 5 wide
was obtained in this manner. The foamed material had a
fine cell structure and a density of 18 pounds per cubic
foot The compressive strength of this material
according to ASTM D1621 was 60 psi. The modulus of
rupture according to ASTM C209 was 70 psi. No evidence
of cracking was detected when 20-g cubes of the product
were either placed in boiling water for l/2 hour and
allowed to dry~ or wetted with 50 g of water at room
temperature and allowed to dry.
Example 2
` ~ phosphate foam was prepared from the same
components used in Example l. The reaction solution was
prepared by adding 1.04 parts of A12O3.3H2O to 104 parts
of phosphoric acid and stirring the mixture with
moderate agitation for approximately 15 minutes until a
clear solution was obtained. The surfactant (0~1 part)
was then added to the reaction solution. The remaining
dry ingredients (lO0 parts of calcium silicate and 35
parts of aluminum oxide trihydrate) were mixed to~ether
and fed into a Readco continuous processor. The
reaction solution at room temperature, 7~F, was also
fed into the Readco mixer through a different addition
port. The ingredients were proportionally mixed
therein, discharged onto a moving belt covered with a
scrim material and leveled. Foaming began in
approximately 42 seconds and the mass of material became
rigid in approximately 50 seconds. A continuous block
of foa~ed material 1' thick and 5" wide was obtained in
this manner~ The foamed material had a coarse,
irregular cell structure and a density of 17 pounds per
cubic foot. The compressive strength of this material
according to ASTM Dl621 was 50 psi. The moclulus o~
rupture according to ASTM C209 was 50 psi. No evidence
oE craclcing was detected when 20-q cubes o~ ~he product
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were either placed in boiling water for 1/2 hour and-
allowed to dry, or wetted with 50 9 of water at room
temperature and allowed to dry.
F.xample 3
A phosphate foam was prepared from the
following components:
,= . .. -
Parts per
Component Weight (g) 100 parts CaSiO~
A123~3H2 11.44 30.1
MgO (~alcined) 3.0 7.9
80% H3P04 43~56 114.63
(58.0% P20S)
CaSiO3 3~ 100
Surfactant 0.3, 0.79
15 1/2" Polyester Fiber 0.2 0.53
,
If these relationships are calculated by
placing the metal oxide on an anhydrous basis and
including the water of hydration as part o~ the acid
solution, the following is obtained:
:
Parts per 100
Component Parts CaS io~
~123 19.7
MgO tcalcined) 7.9
73-3% ~3P04 125,05
(53.~ P20s)
CclSiO3 100
Surfactant 0.79
lf2" Polyester Fiber 0.53
, .
The reaction solution was prepared by adding
1.15 parts of A1203.3H20 to 114.63 parts of phosphoric
acid and stirring the mixture-with moderate agitation
for approximately 15 minutes until a clear solution ~1as
obtained. The surfactant (0.79 part~ was added to the
.. ..
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reaction solution, which was then cooled to 40F. The
remaining dry ingredients (100 parts of calcium
silicate, 28.95 parts of aluminum oxide trihydrate, 7.9
parts of magnesium oxide and 0.53 parts polyester fiber)
were mixed together~and fed into a Readco continuous
processorO The reaction solution was also fed into the
- Readco mixer through a different addition port. The
ingredients were proportionally mixed therein,
discharged onto a moving belt covered with a scrim
material and leveled. Foaming began in approximately 57
seconds and the mass of material became rigid in
approximately 1 minute 51 seconds. A continuous block
of-foamed material 1" thick and 5" wide was ob~ained in
this manner. The foamed material had a Eine cell
structure and a density of 19 pounds per cubic foot.
The compressive strength of this material according to
AST~. D1621 was 100 psi. The modulus of rupture
according to ASTM C209 was 80 psi. No evidence of
cracking was detected when 20-g cubes of the product
were either placed in boiling water for 1/2 ho~lr and
allowed to dry, or wetted with 50 g of water at room
temperature and allowed to dry.
Example 4
A phosphate foam was prepared from the
following components:
Parts per
Component Weight (g)100 parts CaSiO~
A12O3.3H2o 16.0 40.0
~5~ 1~3PO4 40.0 1~0.0
(61.6% P2Os)
CaSiO3 40.0 100.0
Surfactant 0,04 0.1
If these relationships are calculated by
placing the metal oxide on an anhydrous basis and
inclu~ing the water of hydration as part of the acid
solution, the following is obtained:
-
~6~3il~
-
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Parts per 100
Component Parts CaSiO3
_ ~ .
A123 26.15
74.7~ H3PO~ 113.85
(54.1~ P2O5)
CaSiO3 100
Surfactant 0.1
The reaction solution was prepared by adding
5 parts of Al2O3.3H2O to 100 parts oE phosphoric acid
and stirring the mixture with moderate agitation for
approximately 15 minutes until a clear solution was
obtained. The surfactant t0.1 part) was added to the
reaction solution, which was then cooled to 40F. The
remaining dry ingredients (100 parts of calcium silicate
and 35 parts of aluminum oxide trihydrate) were mixed
together and fed into a Readco continuous processor.
The reaction solution was also fed into the Readco mix~r
through a different addition port. The ingredients were
proportionally mixed therein, discharged onto a moving
belt covered with a scrim material and leveled. Foaming
began in approximately 1 minute 45 seconds and the mass
of material became rigid in approximately 2 minutes 5
seconds. A continuous block of foamed material 1" thick
and 5" wide was obtained in this manner. The foamed
material had a fine cell structure and a density of 29
pounds per cubic foot. The compressive strength of this
material according to ASTM D1621 was 120 psi. The
modulus of rupture according to ASTM C209 was 120 psi.
No evidence of cracking was detected when 20-g cubes of
the product were either placed in boiling water for 1/2
hour and allowed to dry, or wetted ~ith 50 g of water at
room temperature and allowed to dry.
Example 5
A non-foamed phosphate ceramic was prepared
from t~e following components:
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Parts per
Component Weight (g) 100 parts CaSiO3
A123.3H2 18.4 40.89
85~ H3PO4 39.6 88.0
~61.6% P2O5)
CaSiO3 45.0 100
If these relationships are calculated by
placing the metal oxide on an anhydrous basis and
including the water of hydration as part of the acid
solution/ the following is obtained:
Parts per 100
Component Parts CaSiO~
A123 26.73
73.2% H3PO4 102.16
(53.1% P2Os)
CaSiO3 100
The reaction solution was prepared by adding
9.78 parts of A12O3-3H2O to 88 parts of phosphoric acid
and stirring the mixture with moderate agitation for
approximately 15 minutes until a clear solution was
obtained. The remaining dry ingredients (100 parts of
calcium silicate and 31.1 parts of aluminum oxide
trihydrate) were mixed together and fed into a Readco
continuous processor. The reaction solution at room
temperature was also fed into the Readco mixer throuyh a
different addition port. The ingredients were
proportionally mixed therein, discharyed onto a movinq
belt covered with a scrim material and leveled. No
foaming occurred and the mixture set into a solid mass
in 2 minutes 10 seconds. The hard ceramic-like ma~erial
had a density of 60 pounds per cubic foot.
~xample 6
A phosphate ceramic was prepared from the
followiny components:
6~
- 23 - LFM-714
Parts per
Co~ponent Weight (g) 100 parts CaSi~3
A12O3.3H20 17.44 38.76
72% H3PO4 40.56 90.13
t52.18% P2Os)
CaSiO3 45 100
--- ~ Vermiculite
(6#/ft3) 4 8.ag
If these relationships are calculated by
placing the metal oxide on an anhydrous hasis and
including the water of hydration as part of the acid
solution, the following is obtained:
Parts per 100
Component Parts CaSiO~
A1~03 25.34
63% H3PO4 103.55
(45.4% P2Os)
CaSiO3 100
Vermiculite 8.~9
The reac~ion solution was prepared by adding
7.65 parts of ~12O~.3H2O to 90.13 parts of phosphoric
acid and stirring the mixture with moderate agitation
for approximately 15 minutes until a clear solution was -
obtainecl. The remaining dry ingredients (100 parts of-
calcium silicate, 31.11 parts of aluminum oxide
trihydrate and 8.89 parts of vermiculite) were mixed
together and fed into a Readco continuous-processor.
The reaction solution at room temperature (72F) was
also fed into the Readco mixer through a different
addition port. The ingredients were proportionally
mixed therein, discharged onto a moving belt covered
with a scrim material and leveled. No foaming occurred
and t~e mixture set into a solid mass in 2 minutes 30
seconds. The hard ceramic-like material had a density
of 59 pounds per cubic foot.
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Example 7
This example illustrates the use of a prior
art dry foaming agent in combination with the present
invention to produce a phosphate ceramic material. A
phosphate foam was prepared from the following
components:
Parts per
ComponentWeigh_ tg)100 parts CaS _~
A1203.3H20 8.97 17.94
68% H3PO~
(4g.3% P2O5) 56.03 112.0
CaSiO3 50.00 100.0
MgCO3 2.0 4.0
MgO (calcined) 7.0 14.0
Talc Filler10.0 20.n
If these relationships are calculated by
placing the metal oxide on an anhydrous hasis and
including the water of hydration as part of the acid
solution, the following is obtained:
Parts per
Component 100 parts CaSiO~
A123 11.72
64.4% H3PO4
(46.7% P2Os) 118.27
CaSiO3 100.0
MgC03
MgO (calcined~ 14.0
Talc Filler 20.0
The reaction solution was prepared at room
temperature by adding 17.94 parts of A12O3.3H2O with
stirring to 112.06 parts of phosphoric acid solution.
The resulting elear solution was cooled to 55 F. The
remaining dry ingredients (100 part~s of calcium
silicate, 4.0 parts of magnesium carbonate, 14.0 parts
of magnesium oxide and 20.0 parts o~ ~iller) were mixed
.
~.~L8~ 3~l
- 25 - LFM-7149
together and fed into a Readco continuous processor.
The reactLon solution at 55G F was also Eed into the
- Readco mixer through a different addition port. The
inyredients were proportionally mixed therein, and
5 discharged onto a moving belt covered with a scrim
material. Due to the presence of the acid in the
mixture, foaming was occurring as the material exited
the mixer. The foamin~ material was leveled and it
solidified in approximately l minute 30 seconds, with an
exothermic reaction occurring approximately 30 seconds
thereafter as indicated by the evolution of steam. The
rigid foamed material had a fine cell structure and a
density of 12 pounds per cubic foot. The compressive
strength of this material according to ASTM Dl621 was
90 pounds per square inch and the modulus of rupture
according to ASTM C209 was 40 pounds per square inch.
This material floated when placed in water, indlcatlng
that the water could not readilY penetrate the foam
matrix.
Example 8
This example illustrates the use of a liquid
prior art foaming agent to produce the phosphate ceramic
of the present invention. A phosphate ceramic was
prepared from the following cbmponents:
Parts per
ComponentWeight (g)100 parts per CaSiO~
A1203-3H20 9 0 18.0
~0.2% ~3PO4
(58~2% P2Os) 53.0 106~0
CaSiO3 50.0 100.0
Freon-ll 4.0 8.0
MgO (calcined) 5.0 10.0
Talc Filler10.0 20.0
If these relationships are calculated by
placing the metal oxide on an anhydrous basis an~
including the water of hydratlon as part of the acid
solution, the following is obtained:
L3~
- 26 -LFm~7149
Parts per
Component 100 parts Ca.~ 3
A123 11.8
75.8% H3Po4
~55% P2O5) 112.2
CaSiO3 100.0
Freon-ll 8.0
MgO (calcined) 10.0
Talc Filler 20.0
The reaction solution was prepared at room
temperature by mixing 10 parts of ~1~03.3~0 with
stirring to 106.0 parts-of phosphoric acid solutionj
after which the reaction solution was cooled to 55 F.
Thè remaining dry ingredients (100 parts of calcium
silicate, 8.0 parts of aluminum oxide trihydrate,
10.0 parts of magnesium oxide and 20.0 parts of filler)
were mixed together and fed into a Readco continuous
processor. The ingredients were proportionally mixed
therein, the Freon-ll being added through a separate
in-line mixer in order to obtain good dispersion. The
intermixed material exited from the -,nixer and foaming
occurred slowly over a 3-minute period. Solidifaction
occurred in 4 minutes, and the exothermic reaction
occurred in 4~5 minutes. The resulting coarse-celled
foam had a density of 19 pounds per cubic foot.
My invention is not restricted solely to the
descriptions and illustrations provided above, but
encompasses all modifications envisaged by the
following claims.
